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Revision 1.138 by root, Mon Mar 31 01:14:12 2008 UTC vs.
Revision 1.178 by root, Sat Sep 13 18:25:50 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	};
		1012
		1013	...
		1014	struct my_io w;
		1015	ev_io_init (&w.io, my_cb, fd, EV_READ);
954		1016
955	And since your callback will be called with a pointer to the watcher, you	1017	And since your callback will be called with a pointer to the watcher, you
956	can cast it back to your own type:	1018	can cast it back to your own type:
957		1019
958	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	1020	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
959	{	1021	{
960	struct my_io *w = (struct my_io *)w_;	1022	struct my_io *w = (struct my_io *)w_;
961	...	1023	...
962	}	1024	}
963		1025
964	More interesting and less C-conformant ways of casting your callback type	1026	More interesting and less C-conformant ways of casting your callback type
965	instead have been omitted.	1027	instead have been omitted.
966		1028
967	Another common scenario is having some data structure with multiple	1029	Another common scenario is to use some data structure with multiple
968	watchers:	1030	embedded watchers:
969		1031
970	struct my_biggy	1032	struct my_biggy
971	{	1033	{
972	int some_data;	1034	int some_data;
973	ev_timer t1;	1035	ev_timer t1;
974	ev_timer t2;	1036	ev_timer t2;
975	}	1037	}
976		1038
977	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1039	In this case getting the pointer to C<my_biggy> is a bit more
978	you need to use C<offsetof>:	1040	complicated: Either you store the address of your C<my_biggy> struct
		1041	in the C<data> member of the watcher, or you need to use some pointer
		1042	arithmetic using C<offsetof> inside your watchers:
979		1043
980	#include <stddef.h>	1044	#include <stddef.h>
981		1045
982	static void	1046	static void
983	t1_cb (EV_P_ struct ev_timer *w, int revents)	1047	t1_cb (EV_P_ struct ev_timer *w, int revents)
984	{	1048	{
985	struct my_biggy big = (struct my_biggy *	1049	struct my_biggy big = (struct my_biggy *
986	(((char *)w) - offsetof (struct my_biggy, t1));	1050	(((char *)w) - offsetof (struct my_biggy, t1));
987	}	1051	}
988		1052
989	static void	1053	static void
990	t2_cb (EV_P_ struct ev_timer *w, int revents)	1054	t2_cb (EV_P_ struct ev_timer *w, int revents)
991	{	1055	{
992	struct my_biggy big = (struct my_biggy *	1056	struct my_biggy big = (struct my_biggy *
993	(((char *)w) - offsetof (struct my_biggy, t2));	1057	(((char *)w) - offsetof (struct my_biggy, t2));
994	}	1058	}
995		1059
996		1060
997	=head1 WATCHER TYPES	1061	=head1 WATCHER TYPES
998		1062
999	This section describes each watcher in detail, but will not repeat	1063	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	1092	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	1093	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
1030	C<EVBACKEND_POLL>).	1094	C<EVBACKEND_POLL>).
1031		1095
1032	Another thing you have to watch out for is that it is quite easy to	1096	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	1097	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	1098	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	1099	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	1100	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	1101	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	1102	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.	1103	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1040		1104
1041	If you cannot run the fd in non-blocking mode (for example you should not	1105	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	1106	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	1107	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	1108	such as poll (fortunately in our Xlib example, Xlib already does this on
1045	its own, so its quite safe to use).	1109	its own, so its quite safe to use).
1046		1110
1047	=head3 The special problem of disappearing file descriptors	1111	=head3 The special problem of disappearing file descriptors
…		…
1088	C<EVBACKEND_POLL>.	1152	C<EVBACKEND_POLL>.
1089		1153
1090	=head3 The special problem of SIGPIPE	1154	=head3 The special problem of SIGPIPE
1091		1155
1092	While not really specific to libev, it is easy to forget about SIGPIPE:	1156	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	1157	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	1158	send a SIGPIPE, which, by default, aborts your program. For most programs
1095	programs this is sensible behaviour, for daemons, this is usually	1159	this is sensible behaviour, for daemons, this is usually undesirable.
1096	undesirable.
1097		1160
1098	So when you encounter spurious, unexplained daemon exits, make sure you	1161	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	1162	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).	1163	somewhere, as that would have given you a big clue).
1101		1164
…		…
1107	=item ev_io_init (ev_io *, callback, int fd, int events)	1170	=item ev_io_init (ev_io *, callback, int fd, int events)
1108		1171
1109	=item ev_io_set (ev_io *, int fd, int events)	1172	=item ev_io_set (ev_io *, int fd, int events)
1110		1173
1111	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1174	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	1175	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.	1176	C<EV_READ | EV_WRITE> to receive the given events.
1114		1177
1115	=item int fd [read-only]	1178	=item int fd [read-only]
1116		1179
1117	The file descriptor being watched.	1180	The file descriptor being watched.
…		…
1126		1189
1127	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1190	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	1191	readable, but only once. Since it is likely line-buffered, you could
1129	attempt to read a whole line in the callback.	1192	attempt to read a whole line in the callback.
1130		1193
1131	static void	1194	static void
1132	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1195	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1133	{	1196	{
1134	ev_io_stop (loop, w);	1197	ev_io_stop (loop, w);
1135	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1198	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1136	}	1199	}
1137		1200
1138	...	1201	...
1139	struct ev_loop *loop = ev_default_init (0);	1202	struct ev_loop *loop = ev_default_init (0);
1140	struct ev_io stdin_readable;	1203	struct ev_io stdin_readable;
1141	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1204	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1142	ev_io_start (loop, &stdin_readable);	1205	ev_io_start (loop, &stdin_readable);
1143	ev_loop (loop, 0);	1206	ev_loop (loop, 0);
1144		1207
1145		1208
1146	=head2 C<ev_timer> - relative and optionally repeating timeouts	1209	=head2 C<ev_timer> - relative and optionally repeating timeouts
1147		1210
1148	Timer watchers are simple relative timers that generate an event after a	1211	Timer watchers are simple relative timers that generate an event after a
1149	given time, and optionally repeating in regular intervals after that.	1212	given time, and optionally repeating in regular intervals after that.
1150		1213
1151	The timers are based on real time, that is, if you register an event that	1214	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	1215	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	1216	year, it will still time out after (roughly) and hour. "Roughly" because
1154	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1217	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1155	monotonic clock option helps a lot here).	1218	monotonic clock option helps a lot here).
		1219
		1220	The callback is guaranteed to be invoked only after its timeout has passed,
		1221	but if multiple timers become ready during the same loop iteration then
		1222	order of execution is undefined.
		1223
		1224	=head3 The special problem of time updates
		1225
		1226	Establishing the current time is a costly operation (it usually takes at
		1227	least two system calls): EV therefore updates its idea of the current
		1228	time only before and after C<ev_loop> polls for new events, which causes
		1229	a growing difference between C<ev_now ()> and C<ev_time ()> when handling
		1230	lots of events.
1156		1231
1157	The relative timeouts are calculated relative to the C<ev_now ()>	1232	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	1233	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	1234	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	1235	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:	1236	timeout on the current time, use something like this to adjust for this:
1162		1237
1163	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1238	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1164		1239
1165	The callback is guarenteed to be invoked only when its timeout has passed,	1240	If the event loop is suspended for a long time, you can also force an
1166	but if multiple timers become ready during the same loop iteration then	1241	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1167	order of execution is undefined.	1242	()>.
1168		1243
1169	=head3 Watcher-Specific Functions and Data Members	1244	=head3 Watcher-Specific Functions and Data Members
1170		1245
1171	=over 4	1246	=over 4
1172		1247
1173	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1248	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1174		1249
1175	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1250	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1176		1251
1177	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1252	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	1253	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	1254	reached. If it is positive, then the timer will automatically be
1180	later, again, and again, until stopped manually.	1255	configured to trigger again C<repeat> seconds later, again, and again,
		1256	until stopped manually.
1181		1257
1182	The timer itself will do a best-effort at avoiding drift, that is, if you	1258	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	1259	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	1260	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	1261	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.	1262	do stuff) the timer will not fire more than once per event loop iteration.
1187		1263
1188	=item ev_timer_again (loop, ev_timer *)	1264	=item ev_timer_again (loop, ev_timer *)
1189		1265
1190	This will act as if the timer timed out and restart it again if it is	1266	This will act as if the timer timed out and restart it again if it is
1191	repeating. The exact semantics are:	1267	repeating. The exact semantics are:
1192		1268
1193	If the timer is pending, its pending status is cleared.	1269	If the timer is pending, its pending status is cleared.
1194		1270
1195	If the timer is started but nonrepeating, stop it (as if it timed out).	1271	If the timer is started but non-repeating, stop it (as if it timed out).
1196		1272
1197	If the timer is repeating, either start it if necessary (with the	1273	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.	1274	C<repeat> value), or reset the running timer to the C<repeat> value.
1199		1275
1200	This sounds a bit complicated, but here is a useful and typical	1276	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	1277	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	1278	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	1279	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	1280	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	1281	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	1282	you go into an idle state where you do not expect data to travel on the
…		…
1232		1308
1233	=head3 Examples	1309	=head3 Examples
1234		1310
1235	Example: Create a timer that fires after 60 seconds.	1311	Example: Create a timer that fires after 60 seconds.
1236		1312
1237	static void	1313	static void
1238	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1314	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1239	{	1315	{
1240	.. one minute over, w is actually stopped right here	1316	.. one minute over, w is actually stopped right here
1241	}	1317	}
1242		1318
1243	struct ev_timer mytimer;	1319	struct ev_timer mytimer;
1244	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1320	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1245	ev_timer_start (loop, &mytimer);	1321	ev_timer_start (loop, &mytimer);
1246		1322
1247	Example: Create a timeout timer that times out after 10 seconds of	1323	Example: Create a timeout timer that times out after 10 seconds of
1248	inactivity.	1324	inactivity.
1249		1325
1250	static void	1326	static void
1251	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1327	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1252	{	1328	{
1253	.. ten seconds without any activity	1329	.. ten seconds without any activity
1254	}	1330	}
1255		1331
1256	struct ev_timer mytimer;	1332	struct ev_timer mytimer;
1257	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1333	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1258	ev_timer_again (&mytimer); /* start timer */	1334	ev_timer_again (&mytimer); /* start timer */
1259	ev_loop (loop, 0);	1335	ev_loop (loop, 0);
1260		1336
1261	// and in some piece of code that gets executed on any "activity":	1337	// and in some piece of code that gets executed on any "activity":
1262	// reset the timeout to start ticking again at 10 seconds	1338	// reset the timeout to start ticking again at 10 seconds
1263	ev_timer_again (&mytimer);	1339	ev_timer_again (&mytimer);
1264		1340
1265		1341
1266	=head2 C<ev_periodic> - to cron or not to cron?	1342	=head2 C<ev_periodic> - to cron or not to cron?
1267		1343
1268	Periodic watchers are also timers of a kind, but they are very versatile	1344	Periodic watchers are also timers of a kind, but they are very versatile
1269	(and unfortunately a bit complex).	1345	(and unfortunately a bit complex).
1270		1346
1271	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1347	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	1348	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	1349	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 ()	1350	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	1351	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1352	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	1353	to trigger the event (unlike an C<ev_timer>, which would still trigger
1277	roughly 10 seconds later).	1354	roughly 10 seconds later as it uses a relative timeout).
1278		1355
1279	They can also be used to implement vastly more complex timers, such as	1356	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,	1357	such as triggering an event on each "midnight, local time", or other
1281	rules.	1358	complicated, rules.
1282		1359
1283	As with timers, the callback is guarenteed to be invoked only when the	1360	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	1361	time (C<at>) has passed, but if multiple periodic timers become ready
1285	during the same loop iteration then order of execution is undefined.	1362	during the same loop iteration then order of execution is undefined.
1286		1363
1287	=head3 Watcher-Specific Functions and Data Members	1364	=head3 Watcher-Specific Functions and Data Members
1288		1365
1289	=over 4	1366	=over 4
…		…
1297		1374
1298	=over 4	1375	=over 4
1299		1376
1300	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1377	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1301		1378
1302	In this configuration the watcher triggers an event at the wallclock time	1379	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,	1380	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	1381	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.	1382	run when the system time reaches or surpasses this time.
1306		1383
1307	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1384	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1308		1385
1309	In this mode the watcher will always be scheduled to time out at the next	1386	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)	1387	C<at + N * interval> time (for some integer N, which can also be negative)
1311	and then repeat, regardless of any time jumps.	1388	and then repeat, regardless of any time jumps.
1312		1389
1313	This can be used to create timers that do not drift with respect to system	1390	This can be used to create timers that do not drift with respect to system
1314	time:	1391	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1392	the hour:
1315		1393
1316	ev_periodic_set (&periodic, 0., 3600., 0);	1394	ev_periodic_set (&periodic, 0., 3600., 0);
1317		1395
1318	This doesn't mean there will always be 3600 seconds in between triggers,	1396	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	1397	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	1398	full hour (UTC), or more correctly, when the system time is evenly divisible
1321	by 3600.	1399	by 3600.
1322		1400
1323	Another way to think about it (for the mathematically inclined) is that	1401	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	1402	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.	1403	time where C<time = at (mod interval)>, regardless of any time jumps.
1326		1404
1327	For numerical stability it is preferable that the C<at> value is near	1405	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	1406	C<ev_now ()> (the current time), but there is no range requirement for
1329	this value.	1407	this value, and in fact is often specified as zero.
		1408
		1409	Note also that there is an upper limit to how often a timer can fire (CPU
		1410	speed for example), so if C<interval> is very small then timing stability
		1411	will of course deteriorate. Libev itself tries to be exact to be about one
		1412	millisecond (if the OS supports it and the machine is fast enough).
1330		1413
1331	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1414	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1332		1415
1333	In this mode the values for C<interval> and C<at> are both being	1416	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	1417	ignored. Instead, each time the periodic watcher gets scheduled, the
1335	reschedule callback will be called with the watcher as first, and the	1418	reschedule callback will be called with the watcher as first, and the
1336	current time as second argument.	1419	current time as second argument.
1337		1420
1338	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1421	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,	1422	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		1423
		1424	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1425	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1426	only event loop modification you are allowed to do).
		1427
1343	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1428	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1344	ev_tstamp now)>, e.g.:	1429	*w, ev_tstamp now)>, e.g.:
1345		1430
1346	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1431	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1347	{	1432	{
1348	return now + 60.;	1433	return now + 60.;
1349	}	1434	}
…		…
1351	It must return the next time to trigger, based on the passed time value	1436	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	1437	(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	1438	will usually be called just before the callback will be triggered, but
1354	might be called at other times, too.	1439	might be called at other times, too.
1355		1440
1356	NOTE: I<< This callback must always return a time that is later than the	1441	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.	1442	equal to the passed C<now> value >>.
1358		1443
1359	This can be used to create very complex timers, such as a timer that	1444	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	1445	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	1446	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	1447	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).	1448	reason I omitted it as an example).
1364		1449
1365	=back	1450	=back
…		…
1369	Simply stops and restarts the periodic watcher again. This is only useful	1454	Simply stops and restarts the periodic watcher again. This is only useful
1370	when you changed some parameters or the reschedule callback would return	1455	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	1456	a different time than the last time it was called (e.g. in a crond like
1372	program when the crontabs have changed).	1457	program when the crontabs have changed).
1373		1458
		1459	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1460
		1461	When active, returns the absolute time that the watcher is supposed to
		1462	trigger next.
		1463
1374	=item ev_tstamp offset [read-write]	1464	=item ev_tstamp offset [read-write]
1375		1465
1376	When repeating, this contains the offset value, otherwise this is the	1466	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>).	1467	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1378		1468
…		…
1389		1479
1390	The current reschedule callback, or C<0>, if this functionality is	1480	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	1481	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.	1482	the periodic timer fires or C<ev_periodic_again> is being called.
1393		1483
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	1484	=back
1400		1485
1401	=head3 Examples	1486	=head3 Examples
1402		1487
1403	Example: Call a callback every hour, or, more precisely, whenever the	1488	Example: Call a callback every hour, or, more precisely, whenever the
1404	system clock is divisible by 3600. The callback invocation times have	1489	system clock is divisible by 3600. The callback invocation times have
1405	potentially a lot of jittering, but good long-term stability.	1490	potentially a lot of jitter, but good long-term stability.
1406		1491
1407	static void	1492	static void
1408	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1493	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1409	{	1494	{
1410	... its now a full hour (UTC, or TAI or whatever your clock follows)	1495	... its now a full hour (UTC, or TAI or whatever your clock follows)
1411	}	1496	}
1412		1497
1413	struct ev_periodic hourly_tick;	1498	struct ev_periodic hourly_tick;
1414	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1499	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1415	ev_periodic_start (loop, &hourly_tick);	1500	ev_periodic_start (loop, &hourly_tick);
1416		1501
1417	Example: The same as above, but use a reschedule callback to do it:	1502	Example: The same as above, but use a reschedule callback to do it:
1418		1503
1419	#include <math.h>	1504	#include <math.h>
1420		1505
1421	static ev_tstamp	1506	static ev_tstamp
1422	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1507	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1423	{	1508	{
1424	return fmod (now, 3600.) + 3600.;	1509	return fmod (now, 3600.) + 3600.;
1425	}	1510	}
1426		1511
1427	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1512	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1428		1513
1429	Example: Call a callback every hour, starting now:	1514	Example: Call a callback every hour, starting now:
1430		1515
1431	struct ev_periodic hourly_tick;	1516	struct ev_periodic hourly_tick;
1432	ev_periodic_init (&hourly_tick, clock_cb,	1517	ev_periodic_init (&hourly_tick, clock_cb,
1433	fmod (ev_now (loop), 3600.), 3600., 0);	1518	fmod (ev_now (loop), 3600.), 3600., 0);
1434	ev_periodic_start (loop, &hourly_tick);	1519	ev_periodic_start (loop, &hourly_tick);
1435		1520
1436		1521
1437	=head2 C<ev_signal> - signal me when a signal gets signalled!	1522	=head2 C<ev_signal> - signal me when a signal gets signalled!
1438		1523
1439	Signal watchers will trigger an event when the process receives a specific	1524	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	1532	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	1533	watcher for a signal is stopped libev will reset the signal handler to
1449	SIG_DFL (regardless of what it was set to before).	1534	SIG_DFL (regardless of what it was set to before).
1450		1535
1451	If possible and supported, libev will install its handlers with	1536	If possible and supported, libev will install its handlers with
1452	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1537	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1453	interrupted. If you have a problem with syscalls getting interrupted by	1538	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	1539	signals you can block all signals in an C<ev_check> watcher and unblock
1455	them in an C<ev_prepare> watcher.	1540	them in an C<ev_prepare> watcher.
1456		1541
1457	=head3 Watcher-Specific Functions and Data Members	1542	=head3 Watcher-Specific Functions and Data Members
1458		1543
…		…
1473		1558
1474	=head3 Examples	1559	=head3 Examples
1475		1560
1476	Example: Try to exit cleanly on SIGINT and SIGTERM.	1561	Example: Try to exit cleanly on SIGINT and SIGTERM.
1477		1562
1478	static void	1563	static void
1479	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1564	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1480	{	1565	{
1481	ev_unloop (loop, EVUNLOOP_ALL);	1566	ev_unloop (loop, EVUNLOOP_ALL);
1482	}	1567	}
1483		1568
1484	struct ev_signal signal_watcher;	1569	struct ev_signal signal_watcher;
1485	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1570	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1486	ev_signal_start (loop, &sigint_cb);	1571	ev_signal_start (loop, &sigint_cb);
1487		1572
1488		1573
1489	=head2 C<ev_child> - watch out for process status changes	1574	=head2 C<ev_child> - watch out for process status changes
1490		1575
1491	Child watchers trigger when your process receives a SIGCHLD in response to	1576	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	1578	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	1579	forked (which implies it might have already exited), as long as the event
1495	loop isn't entered (or is continued from a watcher).	1580	loop isn't entered (or is continued from a watcher).
1496		1581
1497	Only the default event loop is capable of handling signals, and therefore	1582	Only the default event loop is capable of handling signals, and therefore
1498	you can only rgeister child watchers in the default event loop.	1583	you can only register child watchers in the default event loop.
1499		1584
1500	=head3 Process Interaction	1585	=head3 Process Interaction
1501		1586
1502	Libev grabs C<SIGCHLD> as soon as the default event loop is	1587	Libev grabs C<SIGCHLD> as soon as the default event loop is
1503	initialised. This is necessary to guarantee proper behaviour even if	1588	initialised. This is necessary to guarantee proper behaviour even if
1504	the first child watcher is started after the child exits. The occurance	1589	the first child watcher is started after the child exits. The occurrence
1505	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1590	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1506	synchronously as part of the event loop processing. Libev always reaps all	1591	synchronously as part of the event loop processing. Libev always reaps all
1507	children, even ones not watched.	1592	children, even ones not watched.
1508		1593
1509	=head3 Overriding the Built-In Processing	1594	=head3 Overriding the Built-In Processing
…		…
1513	handler, you can override it easily by installing your own handler for	1598	handler, you can override it easily by installing your own handler for
1514	C<SIGCHLD> after initialising the default loop, and making sure the	1599	C<SIGCHLD> after initialising the default loop, and making sure the
1515	default loop never gets destroyed. You are encouraged, however, to use an	1600	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	1601	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.	1602	that, so other libev users can use C<ev_child> watchers freely.
		1603
		1604	=head3 Stopping the Child Watcher
		1605
		1606	Currently, the child watcher never gets stopped, even when the
		1607	child terminates, so normally one needs to stop the watcher in the
		1608	callback. Future versions of libev might stop the watcher automatically
		1609	when a child exit is detected.
1518		1610
1519	=head3 Watcher-Specific Functions and Data Members	1611	=head3 Watcher-Specific Functions and Data Members
1520		1612
1521	=over 4	1613	=over 4
1522		1614
…		…
1551	=head3 Examples	1643	=head3 Examples
1552		1644
1553	Example: C<fork()> a new process and install a child handler to wait for	1645	Example: C<fork()> a new process and install a child handler to wait for
1554	its completion.	1646	its completion.
1555		1647
1556	ev_child cw;	1648	ev_child cw;
1557		1649
1558	static void	1650	static void
1559	child_cb (EV_P_ struct ev_child *w, int revents)	1651	child_cb (EV_P_ struct ev_child *w, int revents)
1560	{	1652	{
1561	ev_child_stop (EV_A_ w);	1653	ev_child_stop (EV_A_ w);
1562	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1654	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1563	}	1655	}
1564		1656
1565	pid_t pid = fork ();	1657	pid_t pid = fork ();
1566		1658
1567	if (pid < 0)	1659	if (pid < 0)
1568	// error	1660	// error
1569	else if (pid == 0)	1661	else if (pid == 0)
1570	{	1662	{
1571	// the forked child executes here	1663	// the forked child executes here
1572	exit (1);	1664	exit (1);
1573	}	1665	}
1574	else	1666	else
1575	{	1667	{
1576	ev_child_init (&cw, child_cb, pid, 0);	1668	ev_child_init (&cw, child_cb, pid, 0);
1577	ev_child_start (EV_DEFAULT_ &cw);	1669	ev_child_start (EV_DEFAULT_ &cw);
1578	}	1670	}
1579		1671
1580		1672
1581	=head2 C<ev_stat> - did the file attributes just change?	1673	=head2 C<ev_stat> - did the file attributes just change?
1582		1674
1583	This watches a filesystem path for attribute changes. That is, it calls	1675	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	1676	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.	1677	compared to the last time, invoking the callback if it did.
1586		1678
1587	The path does not need to exist: changing from "path exists" to "path does	1679	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	1680	not exist" is a status change like any other. The condition "path does
…		…
1606	as even with OS-supported change notifications, this can be	1698	as even with OS-supported change notifications, this can be
1607	resource-intensive.	1699	resource-intensive.
1608		1700
1609	At the time of this writing, only the Linux inotify interface is	1701	At the time of this writing, only the Linux inotify interface is
1610	implemented (implementing kqueue support is left as an exercise for the	1702	implemented (implementing kqueue support is left as an exercise for the
		1703	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	1704	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	1705	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	1706	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	1707	but changes are usually detected immediately, and if the file exists there
1615	polling.	1708	will be no polling.
1616		1709
1617	=head3 ABI Issues (Largefile Support)	1710	=head3 ABI Issues (Largefile Support)
1618		1711
1619	Libev by default (unless the user overrides this) uses the default	1712	Libev by default (unless the user overrides this) uses the default
1620	compilation environment, which means that on systems with optionally	1713	compilation environment, which means that on systems with large file
1621	disabled large file support, you get the 32 bit version of the stat	1714	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	1715	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	1716	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	1717	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	1718	obviously the case with any flags that change the ABI, but the problem is
1626	most noticably with ev_stat and largefile support.	1719	most noticeably disabled with ev_stat and large file support.
		1720
		1721	The solution for this is to lobby your distribution maker to make large
		1722	file interfaces available by default (as e.g. FreeBSD does) and not
		1723	optional. Libev cannot simply switch on large file support because it has
		1724	to exchange stat structures with application programs compiled using the
		1725	default compilation environment.
1627		1726
1628	=head3 Inotify	1727	=head3 Inotify
1629		1728
1630	When C<inotify (7)> support has been compiled into libev (generally only	1729	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	1730	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	1731	change detection where possible. The inotify descriptor will be created lazily
1633	when the first C<ev_stat> watcher is being started.	1732	when the first C<ev_stat> watcher is being started.
1634		1733
1635	Inotify presense does not change the semantics of C<ev_stat> watchers	1734	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	1735	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	1736	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.	1737	there are many cases where libev has to resort to regular C<stat> polling.
1639		1738
1640	(There is no support for kqueue, as apparently it cannot be used to	1739	(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	1740	implement this functionality, due to the requirement of having a file
1642	descriptor open on the object at all times).	1741	descriptor open on the object at all times).
1643		1742
1644	=head3 The special problem of stat time resolution	1743	=head3 The special problem of stat time resolution
1645		1744
1646	The C<stat ()> syscall only supports full-second resolution portably, and	1745	The C<stat ()> system call only supports full-second resolution portably, and
1647	even on systems where the resolution is higher, many filesystems still	1746	even on systems where the resolution is higher, many file systems still
1648	only support whole seconds.	1747	only support whole seconds.
1649		1748
1650	That means that, if the time is the only thing that changes, you might	1749	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	1750	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	1751	calls your callback, which does something. When there is another update
1653	the same second, C<ev_stat> will be unable to detect it.	1752	within the same second, C<ev_stat> will be unable to detect it as the stat
		1753	data does not change.
1654		1754
1655	The solution to this is to delay acting on a change for a second (or till	1755	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>	1756	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>	1757	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	1758	ev_timer_again (loop, w)>).
1659	systems.	1759
		1760	The C<.02> offset is added to work around small timing inconsistencies
		1761	of some operating systems (where the second counter of the current time
		1762	might be be delayed. One such system is the Linux kernel, where a call to
		1763	C<gettimeofday> might return a timestamp with a full second later than
		1764	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1765	update file times then there will be a small window where the kernel uses
		1766	the previous second to update file times but libev might already execute
		1767	the timer callback).
1660		1768
1661	=head3 Watcher-Specific Functions and Data Members	1769	=head3 Watcher-Specific Functions and Data Members
1662		1770
1663	=over 4	1771	=over 4
1664		1772
…		…
1670	C<path>. The C<interval> is a hint on how quickly a change is expected to	1778	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	1779	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	1780	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.	1781	path for as long as the watcher is active.
1674		1782
1675	The callback will be receive C<EV_STAT> when a change was detected,	1783	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	1784	to the attributes at the time the watcher was started (or the last change
1677	last change was detected).	1785	was detected).
1678		1786
1679	=item ev_stat_stat (loop, ev_stat *)	1787	=item ev_stat_stat (loop, ev_stat *)
1680		1788
1681	Updates the stat buffer immediately with new values. If you change the	1789	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	1790	watched path in your callback, you could call this function to avoid
1683	detecting this change (while introducing a race condition). Can also be	1791	detecting this change (while introducing a race condition if you are not
1684	useful simply to find out the new values.	1792	the only one changing the path). Can also be useful simply to find out the
		1793	new values.
1685		1794
1686	=item ev_statdata attr [read-only]	1795	=item ev_statdata attr [read-only]
1687		1796
1688	The most-recently detected attributes of the file. Although the type is of	1797	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	1798	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	1799	suitable for your system, but you can only rely on the POSIX-standardised
		1800	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.	1801	some error while C<stat>ing the file.
1692		1802
1693	=item ev_statdata prev [read-only]	1803	=item ev_statdata prev [read-only]
1694		1804
1695	The previous attributes of the file. The callback gets invoked whenever	1805	The previous attributes of the file. The callback gets invoked whenever
1696	C<prev> != C<attr>.	1806	C<prev> != C<attr>, or, more precisely, one or more of these members
		1807	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1808	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1697		1809
1698	=item ev_tstamp interval [read-only]	1810	=item ev_tstamp interval [read-only]
1699		1811
1700	The specified interval.	1812	The specified interval.
1701		1813
1702	=item const char *path [read-only]	1814	=item const char *path [read-only]
1703		1815
1704	The filesystem path that is being watched.	1816	The file system path that is being watched.
1705		1817
1706	=back	1818	=back
1707		1819
1708	=head3 Examples	1820	=head3 Examples
1709		1821
1710	Example: Watch C</etc/passwd> for attribute changes.	1822	Example: Watch C</etc/passwd> for attribute changes.
1711		1823
1712	static void	1824	static void
1713	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1825	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1714	{	1826	{
1715	/* /etc/passwd changed in some way */	1827	/* /etc/passwd changed in some way */
1716	if (w->attr.st_nlink)	1828	if (w->attr.st_nlink)
1717	{	1829	{
1718	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1830	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1719	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1831	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1720	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1832	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1721	}	1833	}
1722	else	1834	else
1723	/* you shalt not abuse printf for puts */	1835	/* you shalt not abuse printf for puts */
1724	puts ("wow, /etc/passwd is not there, expect problems. "	1836	puts ("wow, /etc/passwd is not there, expect problems. "
1725	"if this is windows, they already arrived\n");	1837	"if this is windows, they already arrived\n");
1726	}	1838	}
1727		1839
1728	...	1840	...
1729	ev_stat passwd;	1841	ev_stat passwd;
1730		1842
1731	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1843	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1732	ev_stat_start (loop, &passwd);	1844	ev_stat_start (loop, &passwd);
1733		1845
1734	Example: Like above, but additionally use a one-second delay so we do not	1846	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	1847	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	1848	one might do the work both on C<ev_stat> callback invocation I<and> on
1737	C<ev_timer> callback invocation).	1849	C<ev_timer> callback invocation).
1738		1850
1739	static ev_stat passwd;	1851	static ev_stat passwd;
1740	static ev_timer timer;	1852	static ev_timer timer;
1741		1853
1742	static void	1854	static void
1743	timer_cb (EV_P_ ev_timer *w, int revents)	1855	timer_cb (EV_P_ ev_timer *w, int revents)
1744	{	1856	{
1745	ev_timer_stop (EV_A_ w);	1857	ev_timer_stop (EV_A_ w);
1746		1858
1747	/* now it's one second after the most recent passwd change */	1859	/* now it's one second after the most recent passwd change */
1748	}	1860	}
1749		1861
1750	static void	1862	static void
1751	stat_cb (EV_P_ ev_stat *w, int revents)	1863	stat_cb (EV_P_ ev_stat *w, int revents)
1752	{	1864	{
1753	/* reset the one-second timer */	1865	/* reset the one-second timer */
1754	ev_timer_again (EV_A_ &timer);	1866	ev_timer_again (EV_A_ &timer);
1755	}	1867	}
1756		1868
1757	...	1869	...
1758	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1870	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1759	ev_stat_start (loop, &passwd);	1871	ev_stat_start (loop, &passwd);
1760	ev_timer_init (&timer, timer_cb, 0., 1.01);	1872	ev_timer_init (&timer, timer_cb, 0., 1.02);
1761		1873
1762		1874
1763	=head2 C<ev_idle> - when you've got nothing better to do...	1875	=head2 C<ev_idle> - when you've got nothing better to do...
1764		1876
1765	Idle watchers trigger events when no other events of the same or higher	1877	Idle watchers trigger events when no other events of the same or higher
…		…
1796	=head3 Examples	1908	=head3 Examples
1797		1909
1798	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1910	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1799	callback, free it. Also, use no error checking, as usual.	1911	callback, free it. Also, use no error checking, as usual.
1800		1912
1801	static void	1913	static void
1802	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1914	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1803	{	1915	{
1804	free (w);	1916	free (w);
1805	// now do something you wanted to do when the program has	1917	// now do something you wanted to do when the program has
1806	// no longer anything immediate to do.	1918	// no longer anything immediate to do.
1807	}	1919	}
1808		1920
1809	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1921	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1810	ev_idle_init (idle_watcher, idle_cb);	1922	ev_idle_init (idle_watcher, idle_cb);
1811	ev_idle_start (loop, idle_cb);	1923	ev_idle_start (loop, idle_cb);
1812		1924
1813		1925
1814	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1926	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1815		1927
1816	Prepare and check watchers are usually (but not always) used in tandem:	1928	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1835		1947
1836	This is done by examining in each prepare call which file descriptors need	1948	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	1949	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	1950	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	1951	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	1952	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	1953	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,	1954	callbacks will never actually be called (but must be valid nevertheless,
1843	because you never know, you know?).	1955	because you never know, you know?).
1844		1956
1845	As another example, the Perl Coro module uses these hooks to integrate	1957	As another example, the Perl Coro module uses these hooks to integrate
…		…
1853		1965
1854	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1966	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	1967	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,	1968	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	1969	too) should not activate ("feed") events into libev. While libev fully
1858	supports this, they will be called before other C<ev_check> watchers	1970	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	1971	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	1972	(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	1973	state until their C<ev_check> watcher ran (always remind yourself to
1862	coexist peacefully with others).	1974	coexist peacefully with others).
1863		1975
…		…
1878	=head3 Examples	1990	=head3 Examples
1879		1991
1880	There are a number of principal ways to embed other event loops or modules	1992	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	1993	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	1994	(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>	1995	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	1996	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1885	into the Glib event loop).	1997	Glib event loop).
1886		1998
1887	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	1999	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	2000	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	2001	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	2002	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.	2003	the callbacks for the IO/timeout watchers might not have been called yet.
1892		2004
1893	static ev_io iow [nfd];	2005	static ev_io iow [nfd];
1894	static ev_timer tw;	2006	static ev_timer tw;
1895		2007
1896	static void	2008	static void
1897	io_cb (ev_loop *loop, ev_io *w, int revents)	2009	io_cb (ev_loop *loop, ev_io *w, int revents)
1898	{	2010	{
1899	}	2011	}
1900		2012
1901	// create io watchers for each fd and a timer before blocking	2013	// create io watchers for each fd and a timer before blocking
1902	static void	2014	static void
1903	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	2015	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1904	{	2016	{
1905	int timeout = 3600000;	2017	int timeout = 3600000;
1906	struct pollfd fds [nfd];	2018	struct pollfd fds [nfd];
1907	// actual code will need to loop here and realloc etc.	2019	// actual code will need to loop here and realloc etc.
1908	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	2020	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1909		2021
1910	/* the callback is illegal, but won't be called as we stop during check */	2022	/* the callback is illegal, but won't be called as we stop during check */
1911	ev_timer_init (&tw, 0, timeout * 1e-3);	2023	ev_timer_init (&tw, 0, timeout * 1e-3);
1912	ev_timer_start (loop, &tw);	2024	ev_timer_start (loop, &tw);
1913		2025
1914	// create one ev_io per pollfd	2026	// create one ev_io per pollfd
1915	for (int i = 0; i < nfd; ++i)	2027	for (int i = 0; i < nfd; ++i)
1916	{	2028	{
1917	ev_io_init (iow + i, io_cb, fds [i].fd,	2029	ev_io_init (iow + i, io_cb, fds [i].fd,
1918	((fds [i].events & POLLIN ? EV_READ : 0)	2030	((fds [i].events & POLLIN ? EV_READ : 0)
1919	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	2031	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1920		2032
1921	fds [i].revents = 0;	2033	fds [i].revents = 0;
1922	ev_io_start (loop, iow + i);	2034	ev_io_start (loop, iow + i);
1923	}	2035	}
1924	}	2036	}
1925		2037
1926	// stop all watchers after blocking	2038	// stop all watchers after blocking
1927	static void	2039	static void
1928	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	2040	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1929	{	2041	{
1930	ev_timer_stop (loop, &tw);	2042	ev_timer_stop (loop, &tw);
1931		2043
1932	for (int i = 0; i < nfd; ++i)	2044	for (int i = 0; i < nfd; ++i)
1933	{	2045	{
1934	// set the relevant poll flags	2046	// set the relevant poll flags
1935	// could also call adns_processreadable etc. here	2047	// could also call adns_processreadable etc. here
1936	struct pollfd *fd = fds + i;	2048	struct pollfd *fd = fds + i;
1937	int revents = ev_clear_pending (iow + i);	2049	int revents = ev_clear_pending (iow + i);
1938	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	2050	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1939	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	2051	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1940		2052
1941	// now stop the watcher	2053	// now stop the watcher
1942	ev_io_stop (loop, iow + i);	2054	ev_io_stop (loop, iow + i);
1943	}	2055	}
1944		2056
1945	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2057	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1946	}	2058	}
1947		2059
1948	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2060	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.	2061	in the prepare watcher and would dispose of the check watcher.
1950		2062
1951	Method 3: If the module to be embedded supports explicit event	2063	Method 3: If the module to be embedded supports explicit event
1952	notification (adns does), you can also make use of the actual watcher	2064	notification (libadns does), you can also make use of the actual watcher
1953	callbacks, and only destroy/create the watchers in the prepare watcher.	2065	callbacks, and only destroy/create the watchers in the prepare watcher.
1954		2066
1955	static void	2067	static void
1956	timer_cb (EV_P_ ev_timer *w, int revents)	2068	timer_cb (EV_P_ ev_timer *w, int revents)
1957	{	2069	{
1958	adns_state ads = (adns_state)w->data;	2070	adns_state ads = (adns_state)w->data;
1959	update_now (EV_A);	2071	update_now (EV_A);
1960		2072
1961	adns_processtimeouts (ads, &tv_now);	2073	adns_processtimeouts (ads, &tv_now);
1962	}	2074	}
1963		2075
1964	static void	2076	static void
1965	io_cb (EV_P_ ev_io *w, int revents)	2077	io_cb (EV_P_ ev_io *w, int revents)
1966	{	2078	{
1967	adns_state ads = (adns_state)w->data;	2079	adns_state ads = (adns_state)w->data;
1968	update_now (EV_A);	2080	update_now (EV_A);
1969		2081
1970	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2082	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1971	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2083	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1972	}	2084	}
1973		2085
1974	// do not ever call adns_afterpoll	2086	// do not ever call adns_afterpoll
1975		2087
1976	Method 4: Do not use a prepare or check watcher because the module you	2088	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	2089	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	2090	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	2091	loop is now no longer controllable by EV. The C<Glib::EV> module does
1980	this.	2092	this.
1981		2093
1982	static gint	2094	static gint
1983	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2095	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1984	{	2096	{
1985	int got_events = 0;	2097	int got_events = 0;
1986		2098
1987	for (n = 0; n < nfds; ++n)	2099	for (n = 0; n < nfds; ++n)
1988	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2100	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1989		2101
1990	if (timeout >= 0)	2102	if (timeout >= 0)
1991	// create/start timer	2103	// create/start timer
1992		2104
1993	// poll	2105	// poll
1994	ev_loop (EV_A_ 0);	2106	ev_loop (EV_A_ 0);
1995		2107
1996	// stop timer again	2108	// stop timer again
1997	if (timeout >= 0)	2109	if (timeout >= 0)
1998	ev_timer_stop (EV_A_ &to);	2110	ev_timer_stop (EV_A_ &to);
1999		2111
2000	// stop io watchers again - their callbacks should have set	2112	// stop io watchers again - their callbacks should have set
2001	for (n = 0; n < nfds; ++n)	2113	for (n = 0; n < nfds; ++n)
2002	ev_io_stop (EV_A_ iow [n]);	2114	ev_io_stop (EV_A_ iow [n]);
2003		2115
2004	return got_events;	2116	return got_events;
2005	}	2117	}
2006		2118
2007		2119
2008	=head2 C<ev_embed> - when one backend isn't enough...	2120	=head2 C<ev_embed> - when one backend isn't enough...
2009		2121
2010	This is a rather advanced watcher type that lets you embed one event loop	2122	This is a rather advanced watcher type that lets you embed one event loop
…		…
2066		2178
2067	Configures the watcher to embed the given loop, which must be	2179	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	2180	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	2181	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,	2182	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).	2183	if you do not want that, you need to temporarily stop the embed watcher).
2072		2184
2073	=item ev_embed_sweep (loop, ev_embed *)	2185	=item ev_embed_sweep (loop, ev_embed *)
2074		2186
2075	Make a single, non-blocking sweep over the embedded loop. This works	2187	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	2188	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2077	apropriate way for embedded loops.	2189	appropriate way for embedded loops.
2078		2190
2079	=item struct ev_loop *other [read-only]	2191	=item struct ev_loop *other [read-only]
2080		2192
2081	The embedded event loop.	2193	The embedded event loop.
2082		2194
…		…
2084		2196
2085	=head3 Examples	2197	=head3 Examples
2086		2198
2087	Example: Try to get an embeddable event loop and embed it into the default	2199	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	2200	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	2201	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	2202	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2091	used).	2203	used).
2092		2204
2093	struct ev_loop *loop_hi = ev_default_init (0);	2205	struct ev_loop *loop_hi = ev_default_init (0);
2094	struct ev_loop *loop_lo = 0;	2206	struct ev_loop *loop_lo = 0;
2095	struct ev_embed embed;	2207	struct ev_embed embed;
2096		2208
2097	// see if there is a chance of getting one that works	2209	// see if there is a chance of getting one that works
2098	// (remember that a flags value of 0 means autodetection)	2210	// (remember that a flags value of 0 means autodetection)
2099	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2211	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2100	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2212	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2101	: 0;	2213	: 0;
2102		2214
2103	// if we got one, then embed it, otherwise default to loop_hi	2215	// if we got one, then embed it, otherwise default to loop_hi
2104	if (loop_lo)	2216	if (loop_lo)
2105	{	2217	{
2106	ev_embed_init (&embed, 0, loop_lo);	2218	ev_embed_init (&embed, 0, loop_lo);
2107	ev_embed_start (loop_hi, &embed);	2219	ev_embed_start (loop_hi, &embed);
2108	}	2220	}
2109	else	2221	else
2110	loop_lo = loop_hi;	2222	loop_lo = loop_hi;
2111		2223
2112	Example: Check if kqueue is available but not recommended and create	2224	Example: Check if kqueue is available but not recommended and create
2113	a kqueue backend for use with sockets (which usually work with any	2225	a kqueue backend for use with sockets (which usually work with any
2114	kqueue implementation). Store the kqueue/socket-only event loop in	2226	kqueue implementation). Store the kqueue/socket-only event loop in
2115	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2227	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2116		2228
2117	struct ev_loop *loop = ev_default_init (0);	2229	struct ev_loop *loop = ev_default_init (0);
2118	struct ev_loop *loop_socket = 0;	2230	struct ev_loop *loop_socket = 0;
2119	struct ev_embed embed;	2231	struct ev_embed embed;
2120		2232
2121	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2233	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2122	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2234	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2123	{	2235	{
2124	ev_embed_init (&embed, 0, loop_socket);	2236	ev_embed_init (&embed, 0, loop_socket);
2125	ev_embed_start (loop, &embed);	2237	ev_embed_start (loop, &embed);
2126	}	2238	}
2127		2239
2128	if (!loop_socket)	2240	if (!loop_socket)
2129	loop_socket = loop;	2241	loop_socket = loop;
2130		2242
2131	// now use loop_socket for all sockets, and loop for everything else	2243	// now use loop_socket for all sockets, and loop for everything else
2132		2244
2133		2245
2134	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2246	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2135		2247
2136	Fork watchers are called when a C<fork ()> was detected (usually because	2248	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2189		2301
2190	=item queueing from a signal handler context	2302	=item queueing from a signal handler context
2191		2303
2192	To implement race-free queueing, you simply add to the queue in the signal	2304	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	2305	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2194	some fictitiuous SIGUSR1 handler:	2306	some fictitious SIGUSR1 handler:
2195		2307
2196	static ev_async mysig;	2308	static ev_async mysig;
2197		2309
2198	static void	2310	static void
2199	sigusr1_handler (void)	2311	sigusr1_handler (void)
…		…
2273	=item ev_async_send (loop, ev_async *)	2385	=item ev_async_send (loop, ev_async *)
2274		2386
2275	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2387	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	2388	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	2389	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	2390	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2279	section below on what exactly this means).	2391	section below on what exactly this means).
2280		2392
2281	This call incurs the overhead of a syscall only once per loop iteration,	2393	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	2394	so while the overhead might be noticeable, it doesn't apply to repeated
2283	calls to C<ev_async_send>.	2395	calls to C<ev_async_send>.
		2396
		2397	=item bool = ev_async_pending (ev_async *)
		2398
		2399	Returns a non-zero value when C<ev_async_send> has been called on the
		2400	watcher but the event has not yet been processed (or even noted) by the
		2401	event loop.
		2402
		2403	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
		2404	the loop iterates next and checks for the watcher to have become active,
		2405	it will reset the flag again. C<ev_async_pending> can be used to very
		2406	quickly check whether invoking the loop might be a good idea.
		2407
		2408	Not that this does I<not> check whether the watcher itself is pending, only
		2409	whether it has been requested to make this watcher pending.
2284		2410
2285	=back	2411	=back
2286		2412
2287		2413
2288	=head1 OTHER FUNCTIONS	2414	=head1 OTHER FUNCTIONS
…		…
2299	or timeout without having to allocate/configure/start/stop/free one or	2425	or timeout without having to allocate/configure/start/stop/free one or
2300	more watchers yourself.	2426	more watchers yourself.
2301		2427
2302	If C<fd> is less than 0, then no I/O watcher will be started and events	2428	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	2429	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2304	C<events> set will be craeted and started.	2430	C<events> set will be created and started.
2305		2431
2306	If C<timeout> is less than 0, then no timeout watcher will be	2432	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	2433	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	2434	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2309	dubious value.	2435	dubious value.
…		…
2311	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2437	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	2438	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>	2439	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2314	value passed to C<ev_once>:	2440	value passed to C<ev_once>:
2315		2441
2316	static void stdin_ready (int revents, void *arg)	2442	static void stdin_ready (int revents, void *arg)
2317	{	2443	{
2318	if (revents & EV_TIMEOUT)	2444	if (revents & EV_TIMEOUT)
2319	/* doh, nothing entered */;	2445	/* doh, nothing entered */;
2320	else if (revents & EV_READ)	2446	else if (revents & EV_READ)
2321	/* stdin might have data for us, joy! */;	2447	/* stdin might have data for us, joy! */;
2322	}	2448	}
2323		2449
2324	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2450	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2325		2451
2326	=item ev_feed_event (ev_loop *, watcher *, int revents)	2452	=item ev_feed_event (ev_loop *, watcher *, int revents)
2327		2453
2328	Feeds the given event set into the event loop, as if the specified event	2454	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	2455	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	2460	Feed an event on the given fd, as if a file descriptor backend detected
2335	the given events it.	2461	the given events it.
2336		2462
2337	=item ev_feed_signal_event (ev_loop *loop, int signum)	2463	=item ev_feed_signal_event (ev_loop *loop, int signum)
2338		2464
2339	Feed an event as if the given signal occured (C<loop> must be the default	2465	Feed an event as if the given signal occurred (C<loop> must be the default
2340	loop!).	2466	loop!).
2341		2467
2342	=back	2468	=back
2343		2469
2344		2470
…		…
2360		2486
2361	=item * Priorities are not currently supported. Initialising priorities	2487	=item * Priorities are not currently supported. Initialising priorities
2362	will fail and all watchers will have the same priority, even though there	2488	will fail and all watchers will have the same priority, even though there
2363	is an ev_pri field.	2489	is an ev_pri field.
2364		2490
		2491	=item * In libevent, the last base created gets the signals, in libev, the
		2492	first base created (== the default loop) gets the signals.
		2493
2365	=item * Other members are not supported.	2494	=item * Other members are not supported.
2366		2495
2367	=item * The libev emulation is I<not> ABI compatible to libevent, you need	2496	=item * The libev emulation is I<not> ABI compatible to libevent, you need
2368	to use the libev header file and library.	2497	to use the libev header file and library.
2369		2498
2370	=back	2499	=back
2371		2500
2372	=head1 C++ SUPPORT	2501	=head1 C++ SUPPORT
2373		2502
2374	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2503	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	2504	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.	2505	the callback model to a model using method callbacks on objects.
2377		2506
2378	To use it,	2507	To use it,
2379		2508
2380	#include <ev++.h>	2509	#include <ev++.h>
2381		2510
2382	This automatically includes F<ev.h> and puts all of its definitions (many	2511	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	2512	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	2513	put into the C<ev> namespace. It should support all the same embedding
2385	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2514	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2452	your compiler is good :), then the method will be fully inlined into the	2581	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.	2582	thunking function, making it as fast as a direct C callback.
2454		2583
2455	Example: simple class declaration and watcher initialisation	2584	Example: simple class declaration and watcher initialisation
2456		2585
2457	struct myclass	2586	struct myclass
2458	{	2587	{
2459	void io_cb (ev::io &w, int revents) { }	2588	void io_cb (ev::io &w, int revents) { }
2460	}	2589	}
2461		2590
2462	myclass obj;	2591	myclass obj;
2463	ev::io iow;	2592	ev::io iow;
2464	iow.set <myclass, &myclass::io_cb> (&obj);	2593	iow.set <myclass, &myclass::io_cb> (&obj);
2465		2594
2466	=item w->set<function> (void *data = 0)	2595	=item w->set<function> (void *data = 0)
2467		2596
2468	Also sets a callback, but uses a static method or plain function as	2597	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	2598	callback. The optional C<data> argument will be stored in the watcher's
…		…
2473		2602
2474	See the method-C<set> above for more details.	2603	See the method-C<set> above for more details.
2475		2604
2476	Example:	2605	Example:
2477		2606
2478	static void io_cb (ev::io &w, int revents) { }	2607	static void io_cb (ev::io &w, int revents) { }
2479	iow.set <io_cb> ();	2608	iow.set <io_cb> ();
2480		2609
2481	=item w->set (struct ev_loop *)	2610	=item w->set (struct ev_loop *)
2482		2611
2483	Associates a different C<struct ev_loop> with this watcher. You can only	2612	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).	2613	do this when the watcher is inactive (and not pending either).
2485		2614
2486	=item w->set ([args])	2615	=item w->set ([arguments])
2487		2616
2488	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2617	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	2618	called at least once. Unlike the C counterpart, an active watcher gets
2490	automatically stopped and restarted when reconfiguring it with this	2619	automatically stopped and restarted when reconfiguring it with this
2491	method.	2620	method.
2492		2621
2493	=item w->start ()	2622	=item w->start ()
…		…
2517	=back	2646	=back
2518		2647
2519	Example: Define a class with an IO and idle watcher, start one of them in	2648	Example: Define a class with an IO and idle watcher, start one of them in
2520	the constructor.	2649	the constructor.
2521		2650
2522	class myclass	2651	class myclass
2523	{	2652	{
2524	ev::io io; void io_cb (ev::io &w, int revents);	2653	ev::io io; void io_cb (ev::io &w, int revents);
2525	ev:idle idle void idle_cb (ev::idle &w, int revents);	2654	ev:idle idle void idle_cb (ev::idle &w, int revents);
2526		2655
2527	myclass (int fd)	2656	myclass (int fd)
2528	{	2657	{
2529	io .set <myclass, &myclass::io_cb > (this);	2658	io .set <myclass, &myclass::io_cb > (this);
2530	idle.set <myclass, &myclass::idle_cb> (this);	2659	idle.set <myclass, &myclass::idle_cb> (this);
2531		2660
2532	io.start (fd, ev::READ);	2661	io.start (fd, ev::READ);
2533	}	2662	}
2534	};	2663	};
2535		2664
2536		2665
2537	=head1 OTHER LANGUAGE BINDINGS	2666	=head1 OTHER LANGUAGE BINDINGS
2538		2667
2539	Libev does not offer other language bindings itself, but bindings for a	2668	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	2669	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	2670	any interesting language binding in addition to the ones listed here, drop
2542	me a note.	2671	me a note.
2543		2672
2544	=over 4	2673	=over 4
2545		2674
…		…
2549	libev. EV is developed together with libev. Apart from the EV core module,	2678	libev. EV is developed together with libev. Apart from the EV core module,
2550	there are additional modules that implement libev-compatible interfaces	2679	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	2680	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>).	2681	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2553		2682
2554	It can be found and installed via CPAN, its homepage is found at	2683	It can be found and installed via CPAN, its homepage is at
2555	L<http://software.schmorp.de/pkg/EV>.	2684	L<http://software.schmorp.de/pkg/EV>.
2556		2685
		2686	=item Python
		2687
		2688	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2689	seems to be quite complete and well-documented. Note, however, that the
		2690	patch they require for libev is outright dangerous as it breaks the ABI
		2691	for everybody else, and therefore, should never be applied in an installed
		2692	libev (if python requires an incompatible ABI then it needs to embed
		2693	libev).
		2694
2557	=item Ruby	2695	=item Ruby
2558		2696
2559	Tony Arcieri has written a ruby extension that offers access to a subset	2697	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	2698	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	2699	more on top of it. It can be found via gem servers. Its homepage is at
2562	L<http://rev.rubyforge.org/>.	2700	L<http://rev.rubyforge.org/>.
2563		2701
2564	=item D	2702	=item D
2565		2703
2566	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	2704	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>.	2705	be found at L<http://proj.llucax.com.ar/wiki/evd>.
2568		2706
2569	=back	2707	=back
2570		2708
2571		2709
2572	=head1 MACRO MAGIC	2710	=head1 MACRO MAGIC
2573		2711
2574	Libev can be compiled with a variety of options, the most fundamantal	2712	Libev can be compiled with a variety of options, the most fundamental
2575	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2713	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2576	functions and callbacks have an initial C<struct ev_loop *> argument.	2714	functions and callbacks have an initial C<struct ev_loop *> argument.
2577		2715
2578	To make it easier to write programs that cope with either variant, the	2716	To make it easier to write programs that cope with either variant, the
2579	following macros are defined:	2717	following macros are defined:
…		…
2584		2722
2585	This provides the loop I<argument> for functions, if one is required ("ev	2723	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,	2724	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:	2725	C<EV_A_> is used when other arguments are following. Example:
2588		2726
2589	ev_unref (EV_A);	2727	ev_unref (EV_A);
2590	ev_timer_add (EV_A_ watcher);	2728	ev_timer_add (EV_A_ watcher);
2591	ev_loop (EV_A_ 0);	2729	ev_loop (EV_A_ 0);
2592		2730
2593	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2731	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2594	which is often provided by the following macro.	2732	which is often provided by the following macro.
2595		2733
2596	=item C<EV_P>, C<EV_P_>	2734	=item C<EV_P>, C<EV_P_>
2597		2735
2598	This provides the loop I<parameter> for functions, if one is required ("ev	2736	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,	2737	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:	2738	C<EV_P_> is used when other parameters are following. Example:
2601		2739
2602	// this is how ev_unref is being declared	2740	// this is how ev_unref is being declared
2603	static void ev_unref (EV_P);	2741	static void ev_unref (EV_P);
2604		2742
2605	// this is how you can declare your typical callback	2743	// this is how you can declare your typical callback
2606	static void cb (EV_P_ ev_timer *w, int revents)	2744	static void cb (EV_P_ ev_timer *w, int revents)
2607		2745
2608	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2746	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2609	suitable for use with C<EV_A>.	2747	suitable for use with C<EV_A>.
2610		2748
2611	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2749	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
2612		2750
2613	Similar to the other two macros, this gives you the value of the default	2751	Similar to the other two macros, this gives you the value of the default
2614	loop, if multiple loops are supported ("ev loop default").	2752	loop, if multiple loops are supported ("ev loop default").
		2753
		2754	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
		2755
		2756	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
		2757	default loop has been initialised (C<UC> == unchecked). Their behaviour
		2758	is undefined when the default loop has not been initialised by a previous
		2759	execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
		2760
		2761	It is often prudent to use C<EV_DEFAULT> when initialising the first
		2762	watcher in a function but use C<EV_DEFAULT_UC> afterwards.
2615		2763
2616	=back	2764	=back
2617		2765
2618	Example: Declare and initialise a check watcher, utilising the above	2766	Example: Declare and initialise a check watcher, utilising the above
2619	macros so it will work regardless of whether multiple loops are supported	2767	macros so it will work regardless of whether multiple loops are supported
2620	or not.	2768	or not.
2621		2769
2622	static void	2770	static void
2623	check_cb (EV_P_ ev_timer *w, int revents)	2771	check_cb (EV_P_ ev_timer *w, int revents)
2624	{	2772	{
2625	ev_check_stop (EV_A_ w);	2773	ev_check_stop (EV_A_ w);
2626	}	2774	}
2627		2775
2628	ev_check check;	2776	ev_check check;
2629	ev_check_init (&check, check_cb);	2777	ev_check_init (&check, check_cb);
2630	ev_check_start (EV_DEFAULT_ &check);	2778	ev_check_start (EV_DEFAULT_ &check);
2631	ev_loop (EV_DEFAULT_ 0);	2779	ev_loop (EV_DEFAULT_ 0);
2632		2780
2633	=head1 EMBEDDING	2781	=head1 EMBEDDING
2634		2782
2635	Libev can (and often is) directly embedded into host	2783	Libev can (and often is) directly embedded into host
2636	applications. Examples of applications that embed it include the Deliantra	2784	applications. Examples of applications that embed it include the Deliantra
…		…
2643	libev somewhere in your source tree).	2791	libev somewhere in your source tree).
2644		2792
2645	=head2 FILESETS	2793	=head2 FILESETS
2646		2794
2647	Depending on what features you need you need to include one or more sets of files	2795	Depending on what features you need you need to include one or more sets of files
2648	in your app.	2796	in your application.
2649		2797
2650	=head3 CORE EVENT LOOP	2798	=head3 CORE EVENT LOOP
2651		2799
2652	To include only the libev core (all the C<ev_*> functions), with manual	2800	To include only the libev core (all the C<ev_*> functions), with manual
2653	configuration (no autoconf):	2801	configuration (no autoconf):
2654		2802
2655	#define EV_STANDALONE 1	2803	#define EV_STANDALONE 1
2656	#include "ev.c"	2804	#include "ev.c"
2657		2805
2658	This will automatically include F<ev.h>, too, and should be done in a	2806	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	2807	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	2808	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	2809	done by writing a wrapper around F<ev.h> that you can include instead and
2662	where you can put other configuration options):	2810	where you can put other configuration options):
2663		2811
2664	#define EV_STANDALONE 1	2812	#define EV_STANDALONE 1
2665	#include "ev.h"	2813	#include "ev.h"
2666		2814
2667	Both header files and implementation files can be compiled with a C++	2815	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	2816	compiler (at least, thats a stated goal, and breakage will be treated
2669	as a bug).	2817	as a bug).
2670		2818
2671	You need the following files in your source tree, or in a directory	2819	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):	2820	in your include path (e.g. in libev/ when using -Ilibev):
2673		2821
2674	ev.h	2822	ev.h
2675	ev.c	2823	ev.c
2676	ev_vars.h	2824	ev_vars.h
2677	ev_wrap.h	2825	ev_wrap.h
2678		2826
2679	ev_win32.c required on win32 platforms only	2827	ev_win32.c required on win32 platforms only
2680		2828
2681	ev_select.c only when select backend is enabled (which is enabled by default)	2829	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)	2830	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)	2831	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)	2832	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)	2833	ev_port.c only when the solaris port backend is enabled (disabled by default)
2686		2834
2687	F<ev.c> includes the backend files directly when enabled, so you only need	2835	F<ev.c> includes the backend files directly when enabled, so you only need
2688	to compile this single file.	2836	to compile this single file.
2689		2837
2690	=head3 LIBEVENT COMPATIBILITY API	2838	=head3 LIBEVENT COMPATIBILITY API
2691		2839
2692	To include the libevent compatibility API, also include:	2840	To include the libevent compatibility API, also include:
2693		2841
2694	#include "event.c"	2842	#include "event.c"
2695		2843
2696	in the file including F<ev.c>, and:	2844	in the file including F<ev.c>, and:
2697		2845
2698	#include "event.h"	2846	#include "event.h"
2699		2847
2700	in the files that want to use the libevent API. This also includes F<ev.h>.	2848	in the files that want to use the libevent API. This also includes F<ev.h>.
2701		2849
2702	You need the following additional files for this:	2850	You need the following additional files for this:
2703		2851
2704	event.h	2852	event.h
2705	event.c	2853	event.c
2706		2854
2707	=head3 AUTOCONF SUPPORT	2855	=head3 AUTOCONF SUPPORT
2708		2856
2709	Instead of using C<EV_STANDALONE=1> and providing your config in	2857	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	2858	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	2859	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2712	include F<config.h> and configure itself accordingly.	2860	include F<config.h> and configure itself accordingly.
2713		2861
2714	For this of course you need the m4 file:	2862	For this of course you need the m4 file:
2715		2863
2716	libev.m4	2864	libev.m4
2717		2865
2718	=head2 PREPROCESSOR SYMBOLS/MACROS	2866	=head2 PREPROCESSOR SYMBOLS/MACROS
2719		2867
2720	Libev can be configured via a variety of preprocessor symbols you have to define	2868	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	2869	define before including any of its files. The default in the absence of
2722	and only include the select backend.	2870	autoconf is noted for every option.
2723		2871
2724	=over 4	2872	=over 4
2725		2873
2726	=item EV_STANDALONE	2874	=item EV_STANDALONE
2727		2875
…		…
2732	F<event.h> that are not directly supported by the libev core alone.	2880	F<event.h> that are not directly supported by the libev core alone.
2733		2881
2734	=item EV_USE_MONOTONIC	2882	=item EV_USE_MONOTONIC
2735		2883
2736	If defined to be C<1>, libev will try to detect the availability of the	2884	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	2885	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	2886	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	2887	usually have to link against librt or something similar. Enabling it when
2740	the functionality isn't available is safe, though, although you have	2888	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>	2889	to make sure you link against any libraries where the C<clock_gettime>
2742	function is hiding in (often F<-lrt>).	2890	function is hiding in (often F<-lrt>).
2743		2891
2744	=item EV_USE_REALTIME	2892	=item EV_USE_REALTIME
2745		2893
2746	If defined to be C<1>, libev will try to detect the availability of the	2894	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	2895	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	2896	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	2897	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2750	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2898	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2751	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2899	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2752		2900
2753	=item EV_USE_NANOSLEEP	2901	=item EV_USE_NANOSLEEP
2754		2902
2755	If defined to be C<1>, libev will assume that C<nanosleep ()> is available	2903	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 ()>.	2904	and will use it for delays. Otherwise it will use C<select ()>.
2757		2905
		2906	=item EV_USE_EVENTFD
		2907
		2908	If defined to be C<1>, then libev will assume that C<eventfd ()> is
		2909	available and will probe for kernel support at runtime. This will improve
		2910	C<ev_signal> and C<ev_async> performance and reduce resource consumption.
		2911	If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
		2912	2.7 or newer, otherwise disabled.
		2913
2758	=item EV_USE_SELECT	2914	=item EV_USE_SELECT
2759		2915
2760	If undefined or defined to be C<1>, libev will compile in support for the	2916	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	2917	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	2918	other method takes over, select will be it. Otherwise the select backend
2763	will not be compiled in.	2919	will not be compiled in.
2764		2920
2765	=item EV_SELECT_USE_FD_SET	2921	=item EV_SELECT_USE_FD_SET
2766		2922
2767	If defined to C<1>, then the select backend will use the system C<fd_set>	2923	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	2924	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	2925	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	2926	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	2927	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	2928	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2773	influence the size of the C<fd_set> used.	2929	influence the size of the C<fd_set> used.
2774		2930
…		…
2798		2954
2799	=item EV_USE_EPOLL	2955	=item EV_USE_EPOLL
2800		2956
2801	If defined to be C<1>, libev will compile in support for the Linux	2957	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,	2958	C<epoll>(7) backend. Its availability will be detected at runtime,
2803	otherwise another method will be used as fallback. This is the	2959	otherwise another method will be used as fallback. This is the preferred
2804	preferred backend for GNU/Linux systems.	2960	backend for GNU/Linux systems. If undefined, it will be enabled if the
		2961	headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2805		2962
2806	=item EV_USE_KQUEUE	2963	=item EV_USE_KQUEUE
2807		2964
2808	If defined to be C<1>, libev will compile in support for the BSD style	2965	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,	2966	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	2979	otherwise another method will be used as fallback. This is the preferred
2823	backend for Solaris 10 systems.	2980	backend for Solaris 10 systems.
2824		2981
2825	=item EV_USE_DEVPOLL	2982	=item EV_USE_DEVPOLL
2826		2983
2827	reserved for future expansion, works like the USE symbols above.	2984	Reserved for future expansion, works like the USE symbols above.
2828		2985
2829	=item EV_USE_INOTIFY	2986	=item EV_USE_INOTIFY
2830		2987
2831	If defined to be C<1>, libev will compile in support for the Linux inotify	2988	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	2989	interface to speed up C<ev_stat> watchers. Its actual availability will
2833	be detected at runtime.	2990	be detected at runtime. If undefined, it will be enabled if the headers
		2991	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2834		2992
2835	=item EV_ATOMIC_T	2993	=item EV_ATOMIC_T
2836		2994
2837	Libev requires an integer type (suitable for storing C<0> or C<1>) whose	2995	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	2996	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	2997	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"	2998	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.	2999	as well as for signal and thread safety in C<ev_async> watchers.
2842		3000
2843	In the absense of this define, libev will use C<sig_atomic_t volatile>	3001	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.	3002	(from F<signal.h>), which is usually good enough on most platforms.
2845		3003
2846	=item EV_H	3004	=item EV_H
2847		3005
2848	The name of the F<ev.h> header file used to include it. The default if	3006	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	3045	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	3046	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	3047	and time, so using the defaults of five priorities (-2 .. +2) is usually
2890	fine.	3048	fine.
2891		3049
2892	If your embedding app does not need any priorities, defining these both to	3050	If your embedding application does not need any priorities, defining these both to
2893	C<0> will save some memory and cpu.	3051	C<0> will save some memory and CPU.
2894		3052
2895	=item EV_PERIODIC_ENABLE	3053	=item EV_PERIODIC_ENABLE
2896		3054
2897	If undefined or defined to be C<1>, then periodic timers are supported. If	3055	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	3056	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.	3083	defined to be C<0>, then they are not.
2926		3084
2927	=item EV_MINIMAL	3085	=item EV_MINIMAL
2928		3086
2929	If you need to shave off some kilobytes of code at the expense of some	3087	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	3088	speed, define this symbol to C<1>. Currently this is used to override some
2931	some inlining decisions, saves roughly 30% codesize of amd64.	3089	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3090	much smaller 2-heap for timer management over the default 4-heap.
2932		3091
2933	=item EV_PID_HASHSIZE	3092	=item EV_PID_HASHSIZE
2934		3093
2935	C<ev_child> watchers use a small hash table to distribute workload by	3094	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	3095	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>),	3102	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>	3103	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	3104	watchers you might want to increase this value (I<must> be a power of
2946	two).	3105	two).
2947		3106
		3107	=item EV_USE_4HEAP
		3108
		3109	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3110	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3111	to C<1>. The 4-heap uses more complicated (longer) code but has
		3112	noticeably faster performance with many (thousands) of watchers.
		3113
		3114	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3115	(disabled).
		3116
		3117	=item EV_HEAP_CACHE_AT
		3118
		3119	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3120	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3121	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3122	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3123	but avoids random read accesses on heap changes. This improves performance
		3124	noticeably with with many (hundreds) of watchers.
		3125
		3126	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3127	(disabled).
		3128
		3129	=item EV_VERIFY
		3130
		3131	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3132	be done: If set to C<0>, no internal verification code will be compiled
		3133	in. If set to C<1>, then verification code will be compiled in, but not
		3134	called. If set to C<2>, then the internal verification code will be
		3135	called once per loop, which can slow down libev. If set to C<3>, then the
		3136	verification code will be called very frequently, which will slow down
		3137	libev considerably.
		3138
		3139	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3140	C<0.>
		3141
2948	=item EV_COMMON	3142	=item EV_COMMON
2949		3143
2950	By default, all watchers have a C<void *data> member. By redefining	3144	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	3145	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,	3146	members. You have to define it each time you include one of the files,
2953	though, and it must be identical each time.	3147	though, and it must be identical each time.
2954		3148
2955	For example, the perl EV module uses something like this:	3149	For example, the perl EV module uses something like this:
2956		3150
2957	#define EV_COMMON \	3151	#define EV_COMMON \
2958	SV *self; /* contains this struct */ \	3152	SV *self; /* contains this struct */ \
2959	SV *cb_sv, *fh /* note no trailing ";" */	3153	SV *cb_sv, *fh /* note no trailing ";" */
2960		3154
2961	=item EV_CB_DECLARE (type)	3155	=item EV_CB_DECLARE (type)
2962		3156
2963	=item EV_CB_INVOKE (watcher, revents)	3157	=item EV_CB_INVOKE (watcher, revents)
2964		3158
…		…
2971	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3165	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++.	3166	method calls instead of plain function calls in C++.
2973		3167
2974	=head2 EXPORTED API SYMBOLS	3168	=head2 EXPORTED API SYMBOLS
2975		3169
2976	If you need to re-export the API (e.g. via a dll) and you need a list of	3170	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	3171	exported symbols, you can use the provided F<Symbol.*> files which list
2978	all public symbols, one per line:	3172	all public symbols, one per line:
2979		3173
2980	Symbols.ev for libev proper	3174	Symbols.ev for libev proper
2981	Symbols.event for the libevent emulation	3175	Symbols.event for the libevent emulation
2982		3176
2983	This can also be used to rename all public symbols to avoid clashes with	3177	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	3178	multiple versions of libev linked together (which is obviously bad in
2985	itself, but sometimes it is inconvinient to avoid this).	3179	itself, but sometimes it is inconvenient to avoid this).
2986		3180
2987	A sed command like this will create wrapper C<#define>'s that you need to	3181	A sed command like this will create wrapper C<#define>'s that you need to
2988	include before including F<ev.h>:	3182	include before including F<ev.h>:
2989		3183
2990	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3184	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3007	file.	3201	file.
3008		3202
3009	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3203	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:	3204	that everybody includes and which overrides some configure choices:
3011		3205
3012	#define EV_MINIMAL 1	3206	#define EV_MINIMAL 1
3013	#define EV_USE_POLL 0	3207	#define EV_USE_POLL 0
3014	#define EV_MULTIPLICITY 0	3208	#define EV_MULTIPLICITY 0
3015	#define EV_PERIODIC_ENABLE 0	3209	#define EV_PERIODIC_ENABLE 0
3016	#define EV_STAT_ENABLE 0	3210	#define EV_STAT_ENABLE 0
3017	#define EV_FORK_ENABLE 0	3211	#define EV_FORK_ENABLE 0
3018	#define EV_CONFIG_H <config.h>	3212	#define EV_CONFIG_H <config.h>
3019	#define EV_MINPRI 0	3213	#define EV_MINPRI 0
3020	#define EV_MAXPRI 0	3214	#define EV_MAXPRI 0
3021		3215
3022	#include "ev++.h"	3216	#include "ev++.h"
3023		3217
3024	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3218	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3025		3219
3026	#include "ev_cpp.h"	3220	#include "ev_cpp.h"
3027	#include "ev.c"	3221	#include "ev.c"
		3222
		3223
		3224	=head1 THREADS AND COROUTINES
		3225
		3226	=head2 THREADS
		3227
		3228	Libev itself is completely thread-safe, but it uses no locking. This
		3229	means that you can use as many loops as you want in parallel, as long as
		3230	only one thread ever calls into one libev function with the same loop
		3231	parameter.
		3232
		3233	Or put differently: calls with different loop parameters can be done in
		3234	parallel from multiple threads, calls with the same loop parameter must be
		3235	done serially (but can be done from different threads, as long as only one
		3236	thread ever is inside a call at any point in time, e.g. by using a mutex
		3237	per loop).
		3238
		3239	If you want to know which design (one loop, locking, or multiple loops
		3240	without or something else still) is best for your problem, then I cannot
		3241	help you. I can give some generic advice however:
		3242
		3243	=over 4
		3244
		3245	=item * most applications have a main thread: use the default libev loop
		3246	in that thread, or create a separate thread running only the default loop.
		3247
		3248	This helps integrating other libraries or software modules that use libev
		3249	themselves and don't care/know about threading.
		3250
		3251	=item * one loop per thread is usually a good model.
		3252
		3253	Doing this is almost never wrong, sometimes a better-performance model
		3254	exists, but it is always a good start.
		3255
		3256	=item * other models exist, such as the leader/follower pattern, where one
		3257	loop is handed through multiple threads in a kind of round-robin fashion.
		3258
		3259	Choosing a model is hard - look around, learn, know that usually you can do
		3260	better than you currently do :-)
		3261
		3262	=item * often you need to talk to some other thread which blocks in the
		3263	event loop - C<ev_async> watchers can be used to wake them up from other
		3264	threads safely (or from signal contexts...).
		3265
		3266	=back
		3267
		3268	=head2 COROUTINES
		3269
		3270	Libev is much more accommodating to coroutines ("cooperative threads"):
		3271	libev fully supports nesting calls to it's functions from different
		3272	coroutines (e.g. you can call C<ev_loop> on the same loop from two
		3273	different coroutines and switch freely between both coroutines running the
		3274	loop, as long as you don't confuse yourself). The only exception is that
		3275	you must not do this from C<ev_periodic> reschedule callbacks.
		3276
		3277	Care has been invested into making sure that libev does not keep local
		3278	state inside C<ev_loop>, and other calls do not usually allow coroutine
		3279	switches.
3028		3280
3029		3281
3030	=head1 COMPLEXITIES	3282	=head1 COMPLEXITIES
3031		3283
3032	In this section the complexities of (many of) the algorithms used inside	3284	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	3316	correct watcher to remove. The lists are usually short (you don't usually
3065	have many watchers waiting for the same fd or signal).	3317	have many watchers waiting for the same fd or signal).
3066		3318
3067	=item Finding the next timer in each loop iteration: O(1)	3319	=item Finding the next timer in each loop iteration: O(1)
3068		3320
3069	By virtue of using a binary heap, the next timer is always found at the	3321	By virtue of using a binary or 4-heap, the next timer is always found at a
3070	beginning of the storage array.	3322	fixed position in the storage array.
3071		3323
3072	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3324	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3073		3325
3074	A change means an I/O watcher gets started or stopped, which requires	3326	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	3327	libev to recalculate its status (and possibly tell the kernel, depending
3076	on backend and wether C<ev_io_set> was used).	3328	on backend and whether C<ev_io_set> was used).
3077		3329
3078	=item Activating one watcher (putting it into the pending state): O(1)	3330	=item Activating one watcher (putting it into the pending state): O(1)
3079		3331
3080	=item Priority handling: O(number_of_priorities)	3332	=item Priority handling: O(number_of_priorities)
3081		3333
…		…
3088		3340
3089	=item Processing ev_async_send: O(number_of_async_watchers)	3341	=item Processing ev_async_send: O(number_of_async_watchers)
3090		3342
3091	=item Processing signals: O(max_signal_number)	3343	=item Processing signals: O(max_signal_number)
3092		3344
3093	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3345	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	3346	calls in the current loop iteration. Checking for async and signal events
3095	involves iterating over all running async watchers or all signal numbers.	3347	involves iterating over all running async watchers or all signal numbers.
3096		3348
3097	=back	3349	=back
3098		3350
3099		3351
3100	=head1 Win32 platform limitations and workarounds	3352	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3101		3353
3102	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3354	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	3355	requires, and its I/O model is fundamentally incompatible with the POSIX
3104	model. Libev still offers limited functionality on this platform in	3356	model. Libev still offers limited functionality on this platform in
3105	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3357	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3106	descriptors. This only applies when using Win32 natively, not when using	3358	descriptors. This only applies when using Win32 natively, not when using
3107	e.g. cygwin.	3359	e.g. cygwin.
3108		3360
		3361	Lifting these limitations would basically require the full
		3362	re-implementation of the I/O system. If you are into these kinds of
		3363	things, then note that glib does exactly that for you in a very portable
		3364	way (note also that glib is the slowest event library known to man).
		3365
3109	There is no supported compilation method available on windows except	3366	There is no supported compilation method available on windows except
3110	embedding it into other applications.	3367	embedding it into other applications.
3111		3368
		3369	Not a libev limitation but worth mentioning: windows apparently doesn't
		3370	accept large writes: instead of resulting in a partial write, windows will
		3371	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3372	so make sure you only write small amounts into your sockets (less than a
		3373	megabyte seems safe, but thsi apparently depends on the amount of memory
		3374	available).
		3375
3112	Due to the many, low, and arbitrary limits on the win32 platform and the	3376	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	3377	the abysmal performance of winsockets, using a large number of sockets
3114	recommended (and not reasonable). If your program needs to use more than	3378	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	3379	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	3380	different implementation for windows, as libev offers the POSIX readiness
3117	be implemented efficiently on windows (microsoft monopoly games).	3381	notification model, which cannot be implemented efficiently on windows
		3382	(Microsoft monopoly games).
		3383
		3384	A typical way to use libev under windows is to embed it (see the embedding
		3385	section for details) and use the following F<evwrap.h> header file instead
		3386	of F<ev.h>:
		3387
		3388	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3389	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3390
		3391	#include "ev.h"
		3392
		3393	And compile the following F<evwrap.c> file into your project (make sure
		3394	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3395
		3396	#include "evwrap.h"
		3397	#include "ev.c"
3118		3398
3119	=over 4	3399	=over 4
3120		3400
3121	=item The winsocket select function	3401	=item The winsocket select function
3122		3402
3123	The winsocket C<select> function doesn't follow POSIX in that it requires	3403	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	3404	requires socket I<handles> and not socket I<file descriptors> (it is
3125	very inefficient, and also requires a mapping from file descriptors	3405	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>,	3406	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	3407	C runtime provides the function C<_open_osfhandle> for this). See the
3128	symbols for more info.	3408	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3409	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3129		3410
3130	The configuration for a "naked" win32 using the microsoft runtime	3411	The configuration for a "naked" win32 using the Microsoft runtime
3131	libraries and raw winsocket select is:	3412	libraries and raw winsocket select is:
3132		3413
3133	#define EV_USE_SELECT 1	3414	#define EV_USE_SELECT 1
3134	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3415	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3135		3416
3136	Note that winsockets handling of fd sets is O(n), so you can easily get a	3417	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.	3418	complexity in the O(n²) range when using win32.
3138		3419
3139	=item Limited number of file descriptors	3420	=item Limited number of file descriptors
3140		3421
3141	Windows has numerous arbitrary (and low) limits on things. Early versions	3422	Windows has numerous arbitrary (and low) limits on things.
3142	of winsocket's select only supported waiting for a max. of C<64> handles	3423
		3424	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	3425	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	3426	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).	3427	recommends spawning a chain of threads and wait for 63 handles and the
		3428	previous thread in each. Great).
3146		3429
3147	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3430	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	3431	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	3432	call (which might be in libev or elsewhere, for example, perl does its own
3150	select emulation on windows).	3433	select emulation on windows).
3151		3434
3152	Another limit is the number of file descriptors in the microsoft runtime	3435	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	3436	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	3437	or something like this inside Microsoft). You can increase this by calling
3155	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3438	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3156	arbitrary limit), but is broken in many versions of the microsoft runtime	3439	arbitrary limit), but is broken in many versions of the Microsoft runtime
3157	libraries.	3440	libraries.
3158		3441
3159	This might get you to about C<512> or C<2048> sockets (depending on	3442	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	3443	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	3444	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.	3445	calling select (O(n²)) will likely make this unworkable.
3163		3446
3164	=back	3447	=back
3165		3448
3166		3449
		3450	=head1 PORTABILITY REQUIREMENTS
		3451
		3452	In addition to a working ISO-C implementation, libev relies on a few
		3453	additional extensions:
		3454
		3455	=over 4
		3456
		3457	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3458	calling conventions regardless of C<ev_watcher_type *>.
		3459
		3460	Libev assumes not only that all watcher pointers have the same internal
		3461	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3462	assumes that the same (machine) code can be used to call any watcher
		3463	callback: The watcher callbacks have different type signatures, but libev
		3464	calls them using an C<ev_watcher *> internally.
		3465
		3466	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3467
		3468	The type C<sig_atomic_t volatile> (or whatever is defined as
		3469	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3470	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3471	believed to be sufficiently portable.
		3472
		3473	=item C<sigprocmask> must work in a threaded environment
		3474
		3475	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3476	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3477	pthread implementations will either allow C<sigprocmask> in the "main
		3478	thread" or will block signals process-wide, both behaviours would
		3479	be compatible with libev. Interaction between C<sigprocmask> and
		3480	C<pthread_sigmask> could complicate things, however.
		3481
		3482	The most portable way to handle signals is to block signals in all threads
		3483	except the initial one, and run the default loop in the initial thread as
		3484	well.
		3485
		3486	=item C<long> must be large enough for common memory allocation sizes
		3487
		3488	To improve portability and simplify using libev, libev uses C<long>
		3489	internally instead of C<size_t> when allocating its data structures. On
		3490	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3491	is still at least 31 bits everywhere, which is enough for hundreds of
		3492	millions of watchers.
		3493
		3494	=item C<double> must hold a time value in seconds with enough accuracy
		3495
		3496	The type C<double> is used to represent timestamps. It is required to
		3497	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3498	enough for at least into the year 4000. This requirement is fulfilled by
		3499	implementations implementing IEEE 754 (basically all existing ones).
		3500
		3501	=back
		3502
		3503	If you know of other additional requirements drop me a note.
		3504
		3505
		3506	=head1 COMPILER WARNINGS
		3507
		3508	Depending on your compiler and compiler settings, you might get no or a
		3509	lot of warnings when compiling libev code. Some people are apparently
		3510	scared by this.
		3511
		3512	However, these are unavoidable for many reasons. For one, each compiler
		3513	has different warnings, and each user has different tastes regarding
		3514	warning options. "Warn-free" code therefore cannot be a goal except when
		3515	targeting a specific compiler and compiler-version.
		3516
		3517	Another reason is that some compiler warnings require elaborate
		3518	workarounds, or other changes to the code that make it less clear and less
		3519	maintainable.
		3520
		3521	And of course, some compiler warnings are just plain stupid, or simply
		3522	wrong (because they don't actually warn about the condition their message
		3523	seems to warn about).
		3524
		3525	While libev is written to generate as few warnings as possible,
		3526	"warn-free" code is not a goal, and it is recommended not to build libev
		3527	with any compiler warnings enabled unless you are prepared to cope with
		3528	them (e.g. by ignoring them). Remember that warnings are just that:
		3529	warnings, not errors, or proof of bugs.
		3530
		3531
		3532	=head1 VALGRIND
		3533
		3534	Valgrind has a special section here because it is a popular tool that is
		3535	highly useful, but valgrind reports are very hard to interpret.
		3536
		3537	If you think you found a bug (memory leak, uninitialised data access etc.)
		3538	in libev, then check twice: If valgrind reports something like:
		3539
		3540	==2274== definitely lost: 0 bytes in 0 blocks.
		3541	==2274== possibly lost: 0 bytes in 0 blocks.
		3542	==2274== still reachable: 256 bytes in 1 blocks.
		3543
		3544	Then there is no memory leak. Similarly, under some circumstances,
		3545	valgrind might report kernel bugs as if it were a bug in libev, or it
		3546	might be confused (it is a very good tool, but only a tool).
		3547
		3548	If you are unsure about something, feel free to contact the mailing list
		3549	with the full valgrind report and an explanation on why you think this is
		3550	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3551	no bug" answer and take the chance of learning how to interpret valgrind
		3552	properly.
		3553
		3554	If you need, for some reason, empty reports from valgrind for your project
		3555	I suggest using suppression lists.
		3556
		3557
3167	=head1 AUTHOR	3558	=head1 AUTHOR
3168		3559
3169	Marc Lehmann <libev@schmorp.de>.	3560	Marc Lehmann <libev@schmorp.de>.
3170		3561

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