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Revision 1.142 by root, Sun Apr 6 09:53:18 2008 UTC vs.
Revision 1.173 by root, Thu Aug 7 19:24:56 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
…		…
281	from multiple threads, you have to lock (note also that this is unlikely,	298	from multiple threads, you have to lock (note also that this is unlikely,
282	as loops cannot bes hared easily between threads anyway).	299	as loops cannot bes hared easily between threads anyway).
283		300
284	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
285	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
286	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
287	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
288	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	305	can simply overwrite the C<SIGCHLD> signal handler I<after> calling
289	C<ev_default_init>.	306	C<ev_default_init>.
290		307
291	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
…		…
300	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
301	thing, believe me).	318	thing, believe me).
302		319
303	=item C<EVFLAG_NOENV>	320	=item C<EVFLAG_NOENV>
304		321
305	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
306	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
307	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	324	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
308	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
309	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
310	around bugs.	327	around bugs.
…		…
317		334
318	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,
319	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
320	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
321	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
322	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
323	C<pthread_atfork> which is even faster).	340	C<pthread_atfork> which is even faster).
324		341
325	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
326	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
327	flag.	344	flag.
328		345
329	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>
330	environment variable.	347	environment variable.
331		348
332	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	349	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
333		350
334	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
…		…
336	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
337	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
338	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.
339		356
340	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
341	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
342	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
343	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
344	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
345	readyness notifications you get per iteration.	362	readiness notifications you get per iteration.
346		363
347	=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)
348		365
349	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
350	than select, but handles sparse fds better and has no artificial	367	than select, but handles sparse fds better and has no artificial
…		…
358	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,
359	but it scales phenomenally better. While poll and select usually scale	376	but it scales phenomenally better. While poll and select usually scale
360	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),
361	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
362	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
363	cases and requiring 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
364	support for dup.	381	support for dup.
365		382
366	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
367	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
368	(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
369	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
370	very well if you register events for both fds.	387	very well if you register events for both fds.
371		388
372	Please note that epoll sometimes generates spurious notifications, so you	389	Please note that epoll sometimes generates spurious notifications, so you
…		…
375		392
376	Best performance from this backend is achieved by not unregistering all	393	Best performance from this backend is achieved by not unregistering all
377	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.
378	keep at least one watcher active per fd at all times.	395	keep at least one watcher active per fd at all times.
379		396
380	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
381	all kernel versions tested so far.	398	all kernel versions tested so far.
382		399
383	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	400	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
384		401
385	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
386	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
387	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
388	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"
389	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
390	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)
391	system like NetBSD.	408	system like NetBSD.
392		409
393	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
…		…
395	the target platform). See C<ev_embed> watchers for more info.	412	the target platform). See C<ev_embed> watchers for more info.
396		413
397	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
398	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
399	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
400	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
401	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
402	drops fds silently in similarly hard-to-detect cases.	419	drops fds silently in similarly hard-to-detect cases.
403		420
404	This backend usually performs well under most conditions.	421	This backend usually performs well under most conditions.
405		422
…		…
420	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	437	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
421		438
422	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,
423	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)).
424		441
425	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
426	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
427	blocking when no data (or space) is available.	444	blocking when no data (or space) is available.
428		445
429	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
430	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
431	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	448	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
432	might perform better.	449	might perform better.
433		450
434	On the positive side, ignoring the spurious readyness notifications, this	451	On the positive side, ignoring the spurious readiness notifications, this
435	backend actually performed to specification in all tests and is fully	452	backend actually performed to specification in all tests and is fully
436	embeddable, which is a rare feat among the OS-specific backends.	453	embeddable, which is a rare feat among the OS-specific backends.
437		454
438	=item C<EVBACKEND_ALL>	455	=item C<EVBACKEND_ALL>
439		456
…		…
443		460
444	It is definitely not recommended to use this flag.	461	It is definitely not recommended to use this flag.
445		462
446	=back	463	=back
447		464
448	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
449	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
450	specified, all backends in C<ev_recommended_backends ()> will be tried.	467	specified, all backends in C<ev_recommended_backends ()> will be tried.
451		468
452	The most typical usage is like this:	469	The most typical usage is like this:
453		470
454	if (!ev_default_loop (0))	471	if (!ev_default_loop (0))
455	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	472	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
456		473
457	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
458	environment settings to be taken into account:	475	environment settings to be taken into account:
459		476
460	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);	477	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
461		478
462	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
463	available (warning, breaks stuff, best use only with your own private	480	available (warning, breaks stuff, best use only with your own private
464	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):
465		482
466	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	483	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
467		484
468	=item struct ev_loop *ev_loop_new (unsigned int flags)	485	=item struct ev_loop *ev_loop_new (unsigned int flags)
469		486
470	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
471	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
…		…
476	libev with threads is indeed to create one loop per thread, and using the	493	libev with threads is indeed to create one loop per thread, and using the
477	default loop in the "main" or "initial" thread.	494	default loop in the "main" or "initial" thread.
478		495
479	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.
480		497
481	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	498	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
482	if (!epoller)	499	if (!epoller)
483	fatal ("no epoll found here, maybe it hides under your chair");	500	fatal ("no epoll found here, maybe it hides under your chair");
484		501
485	=item ev_default_destroy ()	502	=item ev_default_destroy ()
486		503
487	Destroys the default loop again (frees all memory and kernel state	504	Destroys the default loop again (frees all memory and kernel state
488	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
489	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
490	responsibility to either stop all watchers cleanly yoursef I<before>	507	responsibility to either stop all watchers cleanly yourself I<before>
491	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
492	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
493	for example).	510	for example).
494		511
495	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
…		…
576	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	593	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle
577	those events and any outstanding ones, but will not block your process in	594	those events and any outstanding ones, but will not block your process in
578	case there are no events and will return after one iteration of the loop.	595	case there are no events and will return after one iteration of the loop.
579		596
580	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	597	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
581	neccessary) and will handle those and any outstanding ones. It will block	598	necessary) and will handle those and any outstanding ones. It will block
582	your process until at least one new event arrives, and will return after	599	your process until at least one new event arrives, and will return after
583	one iteration of the loop. This is useful if you are waiting for some	600	one iteration of the loop. This is useful if you are waiting for some
584	external event in conjunction with something not expressible using other	601	external event in conjunction with something not expressible using other
585	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	602	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
586	usually a better approach for this kind of thing.	603	usually a better approach for this kind of thing.
587		604
588	Here are the gory details of what C<ev_loop> does:	605	Here are the gory details of what C<ev_loop> does:
589		606
590	- Before the first iteration, call any pending watchers.	607	- Before the first iteration, call any pending watchers.
591	* If EVFLAG_FORKCHECK was used, check for a fork.	608	* If EVFLAG_FORKCHECK was used, check for a fork.
592	- If a fork was detected, queue and call all fork watchers.	609	- If a fork was detected (by any means), queue and call all fork watchers.
593	- Queue and call all prepare watchers.	610	- Queue and call all prepare watchers.
594	- If we have been forked, recreate the kernel state.	611	- If we have been forked, detach and recreate the kernel state
		612	as to not disturb the other process.
595	- Update the kernel state with all outstanding changes.	613	- Update the kernel state with all outstanding changes.
596	- Update the "event loop time".	614	- Update the "event loop time" (ev_now ()).
597	- Calculate for how long to sleep or block, if at all	615	- Calculate for how long to sleep or block, if at all
598	(active idle watchers, EVLOOP_NONBLOCK or not having	616	(active idle watchers, EVLOOP_NONBLOCK or not having
599	any active watchers at all will result in not sleeping).	617	any active watchers at all will result in not sleeping).
600	- Sleep if the I/O and timer collect interval say so.	618	- Sleep if the I/O and timer collect interval say so.
601	- Block the process, waiting for any events.	619	- Block the process, waiting for any events.
602	- Queue all outstanding I/O (fd) events.	620	- Queue all outstanding I/O (fd) events.
603	- Update the "event loop time" and do time jump handling.	621	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
604	- Queue all outstanding timers.	622	- Queue all outstanding timers.
605	- Queue all outstanding periodics.	623	- Queue all outstanding periodics.
606	- If no events are pending now, queue all idle watchers.	624	- Unless any events are pending now, queue all idle watchers.
607	- Queue all check watchers.	625	- Queue all check watchers.
608	- Call all queued watchers in reverse order (i.e. check watchers first).	626	- Call all queued watchers in reverse order (i.e. check watchers first).
609	Signals and child watchers are implemented as I/O watchers, and will	627	Signals and child watchers are implemented as I/O watchers, and will
610	be handled here by queueing them when their watcher gets executed.	628	be handled here by queueing them when their watcher gets executed.
611	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	629	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
…		…
616	anymore.	634	anymore.
617		635
618	... queue jobs here, make sure they register event watchers as long	636	... queue jobs here, make sure they register event watchers as long
619	... as they still have work to do (even an idle watcher will do..)	637	... as they still have work to do (even an idle watcher will do..)
620	ev_loop (my_loop, 0);	638	ev_loop (my_loop, 0);
621	... jobs done. yeah!	639	... jobs done or somebody called unloop. yeah!
622		640
623	=item ev_unloop (loop, how)	641	=item ev_unloop (loop, how)
624		642
625	Can be used to make a call to C<ev_loop> return early (but only after it	643	Can be used to make a call to C<ev_loop> return early (but only after it
626	has processed all outstanding events). The C<how> argument must be either	644	has processed all outstanding events). The C<how> argument must be either
…		…
647	respectively).	665	respectively).
648		666
649	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	667	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
650	running when nothing else is active.	668	running when nothing else is active.
651		669
652	struct ev_signal exitsig;	670	struct ev_signal exitsig;
653	ev_signal_init (&exitsig, sig_cb, SIGINT);	671	ev_signal_init (&exitsig, sig_cb, SIGINT);
654	ev_signal_start (loop, &exitsig);	672	ev_signal_start (loop, &exitsig);
655	evf_unref (loop);	673	evf_unref (loop);
656		674
657	Example: For some weird reason, unregister the above signal handler again.	675	Example: For some weird reason, unregister the above signal handler again.
658		676
659	ev_ref (loop);	677	ev_ref (loop);
660	ev_signal_stop (loop, &exitsig);	678	ev_signal_stop (loop, &exitsig);
661		679
662	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	680	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
663		681
664	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	682	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
665		683
666	These advanced functions influence the time that libev will spend waiting	684	These advanced functions influence the time that libev will spend waiting
667	for events. Both are by default C<0>, meaning that libev will try to	685	for events. Both time intervals are by default C<0>, meaning that libev
668	invoke timer/periodic callbacks and I/O callbacks with minimum latency.	686	will try to invoke timer/periodic callbacks and I/O callbacks with minimum
		687	latency.
669		688
670	Setting these to a higher value (the C<interval> I<must> be >= C<0>)	689	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
671	allows libev to delay invocation of I/O and timer/periodic callbacks to	690	allows libev to delay invocation of I/O and timer/periodic callbacks
672	increase efficiency of loop iterations.	691	to increase efficiency of loop iterations (or to increase power-saving
		692	opportunities).
673		693
674	The background is that sometimes your program runs just fast enough to	694	The background is that sometimes your program runs just fast enough to
675	handle one (or very few) event(s) per loop iteration. While this makes	695	handle one (or very few) event(s) per loop iteration. While this makes
676	the program responsive, it also wastes a lot of CPU time to poll for new	696	the program responsive, it also wastes a lot of CPU time to poll for new
677	events, especially with backends like C<select ()> which have a high	697	events, especially with backends like C<select ()> which have a high
…		…
687	to spend more time collecting timeouts, at the expense of increased	707	to spend more time collecting timeouts, at the expense of increased
688	latency (the watcher callback will be called later). C<ev_io> watchers	708	latency (the watcher callback will be called later). C<ev_io> watchers
689	will not be affected. Setting this to a non-null value will not introduce	709	will not be affected. Setting this to a non-null value will not introduce
690	any overhead in libev.	710	any overhead in libev.
691		711
692	Many (busy) programs can usually benefit by setting the io collect	712	Many (busy) programs can usually benefit by setting the I/O collect
693	interval to a value near C<0.1> or so, which is often enough for	713	interval to a value near C<0.1> or so, which is often enough for
694	interactive servers (of course not for games), likewise for timeouts. It	714	interactive servers (of course not for games), likewise for timeouts. It
695	usually doesn't make much sense to set it to a lower value than C<0.01>,	715	usually doesn't make much sense to set it to a lower value than C<0.01>,
696	as this approsaches the timing granularity of most systems.	716	as this approaches the timing granularity of most systems.
		717
		718	Setting the I<timeout collect interval> can improve the opportunity for
		719	saving power, as the program will "bundle" timer callback invocations that
		720	are "near" in time together, by delaying some, thus reducing the number of
		721	times the process sleeps and wakes up again. Another useful technique to
		722	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
		723	they fire on, say, one-second boundaries only.
		724
		725	=item ev_loop_verify (loop)
		726
		727	This function only does something when C<EV_VERIFY> support has been
		728	compiled in. It tries to go through all internal structures and checks
		729	them for validity. If anything is found to be inconsistent, it will print
		730	an error message to standard error and call C<abort ()>.
		731
		732	This can be used to catch bugs inside libev itself: under normal
		733	circumstances, this function will never abort as of course libev keeps its
		734	data structures consistent.
697		735
698	=back	736	=back
699		737
700		738
701	=head1 ANATOMY OF A WATCHER	739	=head1 ANATOMY OF A WATCHER
702		740
703	A watcher is a structure that you create and register to record your	741	A watcher is a structure that you create and register to record your
704	interest in some event. For instance, if you want to wait for STDIN to	742	interest in some event. For instance, if you want to wait for STDIN to
705	become readable, you would create an C<ev_io> watcher for that:	743	become readable, you would create an C<ev_io> watcher for that:
706		744
707	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	745	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
708	{	746	{
709	ev_io_stop (w);	747	ev_io_stop (w);
710	ev_unloop (loop, EVUNLOOP_ALL);	748	ev_unloop (loop, EVUNLOOP_ALL);
711	}	749	}
712		750
713	struct ev_loop *loop = ev_default_loop (0);	751	struct ev_loop *loop = ev_default_loop (0);
714	struct ev_io stdin_watcher;	752	struct ev_io stdin_watcher;
715	ev_init (&stdin_watcher, my_cb);	753	ev_init (&stdin_watcher, my_cb);
716	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	754	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
717	ev_io_start (loop, &stdin_watcher);	755	ev_io_start (loop, &stdin_watcher);
718	ev_loop (loop, 0);	756	ev_loop (loop, 0);
719		757
720	As you can see, you are responsible for allocating the memory for your	758	As you can see, you are responsible for allocating the memory for your
721	watcher structures (and it is usually a bad idea to do this on the stack,	759	watcher structures (and it is usually a bad idea to do this on the stack,
722	although this can sometimes be quite valid).	760	although this can sometimes be quite valid).
723		761
724	Each watcher structure must be initialised by a call to C<ev_init	762	Each watcher structure must be initialised by a call to C<ev_init
725	(watcher *, callback)>, which expects a callback to be provided. This	763	(watcher *, callback)>, which expects a callback to be provided. This
726	callback gets invoked each time the event occurs (or, in the case of io	764	callback gets invoked each time the event occurs (or, in the case of I/O
727	watchers, each time the event loop detects that the file descriptor given	765	watchers, each time the event loop detects that the file descriptor given
728	is readable and/or writable).	766	is readable and/or writable).
729		767
730	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	768	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro
731	with arguments specific to this watcher type. There is also a macro	769	with arguments specific to this watcher type. There is also a macro
…		…
807		845
808	The given async watcher has been asynchronously notified (see C<ev_async>).	846	The given async watcher has been asynchronously notified (see C<ev_async>).
809		847
810	=item C<EV_ERROR>	848	=item C<EV_ERROR>
811		849
812	An unspecified error has occured, the watcher has been stopped. This might	850	An unspecified error has occurred, the watcher has been stopped. This might
813	happen because the watcher could not be properly started because libev	851	happen because the watcher could not be properly started because libev
814	ran out of memory, a file descriptor was found to be closed or any other	852	ran out of memory, a file descriptor was found to be closed or any other
815	problem. You best act on it by reporting the problem and somehow coping	853	problem. You best act on it by reporting the problem and somehow coping
816	with the watcher being stopped.	854	with the watcher being stopped.
817		855
818	Libev will usually signal a few "dummy" events together with an error,	856	Libev will usually signal a few "dummy" events together with an error,
819	for example it might indicate that a fd is readable or writable, and if	857	for example it might indicate that a fd is readable or writable, and if
820	your callbacks is well-written it can just attempt the operation and cope	858	your callbacks is well-written it can just attempt the operation and cope
821	with the error from read() or write(). This will not work in multithreaded	859	with the error from read() or write(). This will not work in multi-threaded
822	programs, though, so beware.	860	programs, though, so beware.
823		861
824	=back	862	=back
825		863
826	=head2 GENERIC WATCHER FUNCTIONS	864	=head2 GENERIC WATCHER FUNCTIONS
…		…
856	Although some watcher types do not have type-specific arguments	894	Although some watcher types do not have type-specific arguments
857	(e.g. C<ev_prepare>) you still need to call its C<set> macro.	895	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
858		896
859	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	897	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
860		898
861	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	899	This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
862	calls into a single call. This is the most convinient method to initialise	900	calls into a single call. This is the most convenient method to initialise
863	a watcher. The same limitations apply, of course.	901	a watcher. The same limitations apply, of course.
864		902
865	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	903	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
866		904
867	Starts (activates) the given watcher. Only active watchers will receive	905	Starts (activates) the given watcher. Only active watchers will receive
…		…
950	to associate arbitrary data with your watcher. If you need more data and	988	to associate arbitrary data with your watcher. If you need more data and
951	don't want to allocate memory and store a pointer to it in that data	989	don't want to allocate memory and store a pointer to it in that data
952	member, you can also "subclass" the watcher type and provide your own	990	member, you can also "subclass" the watcher type and provide your own
953	data:	991	data:
954		992
955	struct my_io	993	struct my_io
956	{	994	{
957	struct ev_io io;	995	struct ev_io io;
958	int otherfd;	996	int otherfd;
959	void *somedata;	997	void *somedata;
960	struct whatever *mostinteresting;	998	struct whatever *mostinteresting;
961	}	999	}
962		1000
963	And since your callback will be called with a pointer to the watcher, you	1001	And since your callback will be called with a pointer to the watcher, you
964	can cast it back to your own type:	1002	can cast it back to your own type:
965		1003
966	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	1004	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
967	{	1005	{
968	struct my_io *w = (struct my_io *)w_;	1006	struct my_io *w = (struct my_io *)w_;
969	...	1007	...
970	}	1008	}
971		1009
972	More interesting and less C-conformant ways of casting your callback type	1010	More interesting and less C-conformant ways of casting your callback type
973	instead have been omitted.	1011	instead have been omitted.
974		1012
975	Another common scenario is having some data structure with multiple	1013	Another common scenario is having some data structure with multiple
976	watchers:	1014	watchers:
977		1015
978	struct my_biggy	1016	struct my_biggy
979	{	1017	{
980	int some_data;	1018	int some_data;
981	ev_timer t1;	1019	ev_timer t1;
982	ev_timer t2;	1020	ev_timer t2;
983	}	1021	}
984		1022
985	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1023	In this case getting the pointer to C<my_biggy> is a bit more complicated,
986	you need to use C<offsetof>:	1024	you need to use C<offsetof>:
987		1025
988	#include <stddef.h>	1026	#include <stddef.h>
989		1027
990	static void	1028	static void
991	t1_cb (EV_P_ struct ev_timer *w, int revents)	1029	t1_cb (EV_P_ struct ev_timer *w, int revents)
992	{	1030	{
993	struct my_biggy big = (struct my_biggy *	1031	struct my_biggy big = (struct my_biggy *
994	(((char *)w) - offsetof (struct my_biggy, t1));	1032	(((char *)w) - offsetof (struct my_biggy, t1));
995	}	1033	}
996		1034
997	static void	1035	static void
998	t2_cb (EV_P_ struct ev_timer *w, int revents)	1036	t2_cb (EV_P_ struct ev_timer *w, int revents)
999	{	1037	{
1000	struct my_biggy big = (struct my_biggy *	1038	struct my_biggy big = (struct my_biggy *
1001	(((char *)w) - offsetof (struct my_biggy, t2));	1039	(((char *)w) - offsetof (struct my_biggy, t2));
1002	}	1040	}
1003		1041
1004		1042
1005	=head1 WATCHER TYPES	1043	=head1 WATCHER TYPES
1006		1044
1007	This section describes each watcher in detail, but will not repeat	1045	This section describes each watcher in detail, but will not repeat
…		…
1036	If you must do this, then force the use of a known-to-be-good backend	1074	If you must do this, then force the use of a known-to-be-good backend
1037	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1075	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
1038	C<EVBACKEND_POLL>).	1076	C<EVBACKEND_POLL>).
1039		1077
1040	Another thing you have to watch out for is that it is quite easy to	1078	Another thing you have to watch out for is that it is quite easy to
1041	receive "spurious" readyness notifications, that is your callback might	1079	receive "spurious" readiness notifications, that is your callback might
1042	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1080	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1043	because there is no data. Not only are some backends known to create a	1081	because there is no data. Not only are some backends known to create a
1044	lot of those (for example solaris ports), it is very easy to get into	1082	lot of those (for example Solaris ports), it is very easy to get into
1045	this situation even with a relatively standard program structure. Thus	1083	this situation even with a relatively standard program structure. Thus
1046	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1084	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1047	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1085	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1048		1086
1049	If you cannot run the fd in non-blocking mode (for example you should not	1087	If you cannot run the fd in non-blocking mode (for example you should not
1050	play around with an Xlib connection), then you have to seperately re-test	1088	play around with an Xlib connection), then you have to separately re-test
1051	whether a file descriptor is really ready with a known-to-be good interface	1089	whether a file descriptor is really ready with a known-to-be good interface
1052	such as poll (fortunately in our Xlib example, Xlib already does this on	1090	such as poll (fortunately in our Xlib example, Xlib already does this on
1053	its own, so its quite safe to use).	1091	its own, so its quite safe to use).
1054		1092
1055	=head3 The special problem of disappearing file descriptors	1093	=head3 The special problem of disappearing file descriptors
…		…
1115	=item ev_io_init (ev_io *, callback, int fd, int events)	1153	=item ev_io_init (ev_io *, callback, int fd, int events)
1116		1154
1117	=item ev_io_set (ev_io *, int fd, int events)	1155	=item ev_io_set (ev_io *, int fd, int events)
1118		1156
1119	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1157	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1120	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1158	receive events for and events is either C<EV_READ>, C<EV_WRITE> or
1121	C<EV_READ | EV_WRITE> to receive the given events.	1159	C<EV_READ | EV_WRITE> to receive the given events.
1122		1160
1123	=item int fd [read-only]	1161	=item int fd [read-only]
1124		1162
1125	The file descriptor being watched.	1163	The file descriptor being watched.
…		…
1134		1172
1135	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1173	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1136	readable, but only once. Since it is likely line-buffered, you could	1174	readable, but only once. Since it is likely line-buffered, you could
1137	attempt to read a whole line in the callback.	1175	attempt to read a whole line in the callback.
1138		1176
1139	static void	1177	static void
1140	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1178	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1141	{	1179	{
1142	ev_io_stop (loop, w);	1180	ev_io_stop (loop, w);
1143	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1181	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1144	}	1182	}
1145		1183
1146	...	1184	...
1147	struct ev_loop *loop = ev_default_init (0);	1185	struct ev_loop *loop = ev_default_init (0);
1148	struct ev_io stdin_readable;	1186	struct ev_io stdin_readable;
1149	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1187	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1150	ev_io_start (loop, &stdin_readable);	1188	ev_io_start (loop, &stdin_readable);
1151	ev_loop (loop, 0);	1189	ev_loop (loop, 0);
1152		1190
1153		1191
1154	=head2 C<ev_timer> - relative and optionally repeating timeouts	1192	=head2 C<ev_timer> - relative and optionally repeating timeouts
1155		1193
1156	Timer watchers are simple relative timers that generate an event after a	1194	Timer watchers are simple relative timers that generate an event after a
1157	given time, and optionally repeating in regular intervals after that.	1195	given time, and optionally repeating in regular intervals after that.
1158		1196
1159	The timers are based on real time, that is, if you register an event that	1197	The timers are based on real time, that is, if you register an event that
1160	times out after an hour and you reset your system clock to last years	1198	times out after an hour and you reset your system clock to January last
1161	time, it will still time out after (roughly) and hour. "Roughly" because	1199	year, it will still time out after (roughly) and hour. "Roughly" because
1162	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1200	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1163	monotonic clock option helps a lot here).	1201	monotonic clock option helps a lot here).
1164		1202
1165	The relative timeouts are calculated relative to the C<ev_now ()>	1203	The relative timeouts are calculated relative to the C<ev_now ()>
1166	time. This is usually the right thing as this timestamp refers to the time	1204	time. This is usually the right thing as this timestamp refers to the time
…		…
1168	you suspect event processing to be delayed and you I<need> to base the timeout	1206	you suspect event processing to be delayed and you I<need> to base the timeout
1169	on the current time, use something like this to adjust for this:	1207	on the current time, use something like this to adjust for this:
1170		1208
1171	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1209	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1172		1210
1173	The callback is guarenteed to be invoked only when its timeout has passed,	1211	The callback is guaranteed to be invoked only after its timeout has passed,
1174	but if multiple timers become ready during the same loop iteration then	1212	but if multiple timers become ready during the same loop iteration then
1175	order of execution is undefined.	1213	order of execution is undefined.
1176		1214
1177	=head3 Watcher-Specific Functions and Data Members	1215	=head3 Watcher-Specific Functions and Data Members
1178		1216
…		…
1180		1218
1181	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1219	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1182		1220
1183	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1221	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1184		1222
1185	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1223	Configure the timer to trigger after C<after> seconds. If C<repeat>
1186	C<0.>, then it will automatically be stopped. If it is positive, then the	1224	is C<0.>, then it will automatically be stopped once the timeout is
1187	timer will automatically be configured to trigger again C<repeat> seconds	1225	reached. If it is positive, then the timer will automatically be
1188	later, again, and again, until stopped manually.	1226	configured to trigger again C<repeat> seconds later, again, and again,
		1227	until stopped manually.
1189		1228
1190	The timer itself will do a best-effort at avoiding drift, that is, if you	1229	The timer itself will do a best-effort at avoiding drift, that is, if
1191	configure a timer to trigger every 10 seconds, then it will trigger at	1230	you configure a timer to trigger every 10 seconds, then it will normally
1192	exactly 10 second intervals. If, however, your program cannot keep up with	1231	trigger at exactly 10 second intervals. If, however, your program cannot
1193	the timer (because it takes longer than those 10 seconds to do stuff) the	1232	keep up with the timer (because it takes longer than those 10 seconds to
1194	timer will not fire more than once per event loop iteration.	1233	do stuff) the timer will not fire more than once per event loop iteration.
1195		1234
1196	=item ev_timer_again (loop, ev_timer *)	1235	=item ev_timer_again (loop, ev_timer *)
1197		1236
1198	This will act as if the timer timed out and restart it again if it is	1237	This will act as if the timer timed out and restart it again if it is
1199	repeating. The exact semantics are:	1238	repeating. The exact semantics are:
1200		1239
1201	If the timer is pending, its pending status is cleared.	1240	If the timer is pending, its pending status is cleared.
1202		1241
1203	If the timer is started but nonrepeating, stop it (as if it timed out).	1242	If the timer is started but non-repeating, stop it (as if it timed out).
1204		1243
1205	If the timer is repeating, either start it if necessary (with the	1244	If the timer is repeating, either start it if necessary (with the
1206	C<repeat> value), or reset the running timer to the C<repeat> value.	1245	C<repeat> value), or reset the running timer to the C<repeat> value.
1207		1246
1208	This sounds a bit complicated, but here is a useful and typical	1247	This sounds a bit complicated, but here is a useful and typical
1209	example: Imagine you have a tcp connection and you want a so-called idle	1248	example: Imagine you have a TCP connection and you want a so-called idle
1210	timeout, that is, you want to be called when there have been, say, 60	1249	timeout, that is, you want to be called when there have been, say, 60
1211	seconds of inactivity on the socket. The easiest way to do this is to	1250	seconds of inactivity on the socket. The easiest way to do this is to
1212	configure an C<ev_timer> with a C<repeat> value of C<60> and then call	1251	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1213	C<ev_timer_again> each time you successfully read or write some data. If	1252	C<ev_timer_again> each time you successfully read or write some data. If
1214	you go into an idle state where you do not expect data to travel on the	1253	you go into an idle state where you do not expect data to travel on the
…		…
1240		1279
1241	=head3 Examples	1280	=head3 Examples
1242		1281
1243	Example: Create a timer that fires after 60 seconds.	1282	Example: Create a timer that fires after 60 seconds.
1244		1283
1245	static void	1284	static void
1246	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1285	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1247	{	1286	{
1248	.. one minute over, w is actually stopped right here	1287	.. one minute over, w is actually stopped right here
1249	}	1288	}
1250		1289
1251	struct ev_timer mytimer;	1290	struct ev_timer mytimer;
1252	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1291	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1253	ev_timer_start (loop, &mytimer);	1292	ev_timer_start (loop, &mytimer);
1254		1293
1255	Example: Create a timeout timer that times out after 10 seconds of	1294	Example: Create a timeout timer that times out after 10 seconds of
1256	inactivity.	1295	inactivity.
1257		1296
1258	static void	1297	static void
1259	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1298	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1260	{	1299	{
1261	.. ten seconds without any activity	1300	.. ten seconds without any activity
1262	}	1301	}
1263		1302
1264	struct ev_timer mytimer;	1303	struct ev_timer mytimer;
1265	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1304	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1266	ev_timer_again (&mytimer); /* start timer */	1305	ev_timer_again (&mytimer); /* start timer */
1267	ev_loop (loop, 0);	1306	ev_loop (loop, 0);
1268		1307
1269	// and in some piece of code that gets executed on any "activity":	1308	// and in some piece of code that gets executed on any "activity":
1270	// reset the timeout to start ticking again at 10 seconds	1309	// reset the timeout to start ticking again at 10 seconds
1271	ev_timer_again (&mytimer);	1310	ev_timer_again (&mytimer);
1272		1311
1273		1312
1274	=head2 C<ev_periodic> - to cron or not to cron?	1313	=head2 C<ev_periodic> - to cron or not to cron?
1275		1314
1276	Periodic watchers are also timers of a kind, but they are very versatile	1315	Periodic watchers are also timers of a kind, but they are very versatile
1277	(and unfortunately a bit complex).	1316	(and unfortunately a bit complex).
1278		1317
1279	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1318	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
1280	but on wallclock time (absolute time). You can tell a periodic watcher	1319	but on wall clock time (absolute time). You can tell a periodic watcher
1281	to trigger "at" some specific point in time. For example, if you tell a	1320	to trigger after some specific point in time. For example, if you tell a
1282	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1321	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()
1283	+ 10.>) and then reset your system clock to the last year, then it will	1322	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1323	clock to January of the previous year, then it will take more than year
1284	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1324	to trigger the event (unlike an C<ev_timer>, which would still trigger
1285	roughly 10 seconds later).	1325	roughly 10 seconds later as it uses a relative timeout).
1286		1326
1287	They can also be used to implement vastly more complex timers, such as	1327	C<ev_periodic>s can also be used to implement vastly more complex timers,
1288	triggering an event on each midnight, local time or other, complicated,	1328	such as triggering an event on each "midnight, local time", or other
1289	rules.	1329	complicated, rules.
1290		1330
1291	As with timers, the callback is guarenteed to be invoked only when the	1331	As with timers, the callback is guaranteed to be invoked only when the
1292	time (C<at>) has been passed, but if multiple periodic timers become ready	1332	time (C<at>) has passed, but if multiple periodic timers become ready
1293	during the same loop iteration then order of execution is undefined.	1333	during the same loop iteration then order of execution is undefined.
1294		1334
1295	=head3 Watcher-Specific Functions and Data Members	1335	=head3 Watcher-Specific Functions and Data Members
1296		1336
1297	=over 4	1337	=over 4
…		…
1305		1345
1306	=over 4	1346	=over 4
1307		1347
1308	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1348	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1309		1349
1310	In this configuration the watcher triggers an event at the wallclock time	1350	In this configuration the watcher triggers an event after the wall clock
1311	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1351	time C<at> has passed and doesn't repeat. It will not adjust when a time
1312	that is, if it is to be run at January 1st 2011 then it will run when the	1352	jump occurs, that is, if it is to be run at January 1st 2011 then it will
1313	system time reaches or surpasses this time.	1353	run when the system time reaches or surpasses this time.
1314		1354
1315	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1355	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1316		1356
1317	In this mode the watcher will always be scheduled to time out at the next	1357	In this mode the watcher will always be scheduled to time out at the next
1318	C<at + N * interval> time (for some integer N, which can also be negative)	1358	C<at + N * interval> time (for some integer N, which can also be negative)
1319	and then repeat, regardless of any time jumps.	1359	and then repeat, regardless of any time jumps.
1320		1360
1321	This can be used to create timers that do not drift with respect to system	1361	This can be used to create timers that do not drift with respect to system
1322	time:	1362	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1363	the hour:
1323		1364
1324	ev_periodic_set (&periodic, 0., 3600., 0);	1365	ev_periodic_set (&periodic, 0., 3600., 0);
1325		1366
1326	This doesn't mean there will always be 3600 seconds in between triggers,	1367	This doesn't mean there will always be 3600 seconds in between triggers,
1327	but only that the the callback will be called when the system time shows a	1368	but only that the callback will be called when the system time shows a
1328	full hour (UTC), or more correctly, when the system time is evenly divisible	1369	full hour (UTC), or more correctly, when the system time is evenly divisible
1329	by 3600.	1370	by 3600.
1330		1371
1331	Another way to think about it (for the mathematically inclined) is that	1372	Another way to think about it (for the mathematically inclined) is that
1332	C<ev_periodic> will try to run the callback in this mode at the next possible	1373	C<ev_periodic> will try to run the callback in this mode at the next possible
1333	time where C<time = at (mod interval)>, regardless of any time jumps.	1374	time where C<time = at (mod interval)>, regardless of any time jumps.
1334		1375
1335	For numerical stability it is preferable that the C<at> value is near	1376	For numerical stability it is preferable that the C<at> value is near
1336	C<ev_now ()> (the current time), but there is no range requirement for	1377	C<ev_now ()> (the current time), but there is no range requirement for
1337	this value.	1378	this value, and in fact is often specified as zero.
		1379
		1380	Note also that there is an upper limit to how often a timer can fire (CPU
		1381	speed for example), so if C<interval> is very small then timing stability
		1382	will of course deteriorate. Libev itself tries to be exact to be about one
		1383	millisecond (if the OS supports it and the machine is fast enough).
1338		1384
1339	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1385	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1340		1386
1341	In this mode the values for C<interval> and C<at> are both being	1387	In this mode the values for C<interval> and C<at> are both being
1342	ignored. Instead, each time the periodic watcher gets scheduled, the	1388	ignored. Instead, each time the periodic watcher gets scheduled, the
1343	reschedule callback will be called with the watcher as first, and the	1389	reschedule callback will be called with the watcher as first, and the
1344	current time as second argument.	1390	current time as second argument.
1345		1391
1346	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1392	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1347	ever, or make any event loop modifications>. If you need to stop it,	1393	ever, or make ANY event loop modifications whatsoever>.
1348	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1349	starting an C<ev_prepare> watcher, which is legal).
1350		1394
		1395	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1396	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1397	only event loop modification you are allowed to do).
		1398
1351	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1399	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1352	ev_tstamp now)>, e.g.:	1400	*w, ev_tstamp now)>, e.g.:
1353		1401
1354	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1402	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1355	{	1403	{
1356	return now + 60.;	1404	return now + 60.;
1357	}	1405	}
…		…
1359	It must return the next time to trigger, based on the passed time value	1407	It must return the next time to trigger, based on the passed time value
1360	(that is, the lowest time value larger than to the second argument). It	1408	(that is, the lowest time value larger than to the second argument). It
1361	will usually be called just before the callback will be triggered, but	1409	will usually be called just before the callback will be triggered, but
1362	might be called at other times, too.	1410	might be called at other times, too.
1363		1411
1364	NOTE: I<< This callback must always return a time that is later than the	1412	NOTE: I<< This callback must always return a time that is higher than or
1365	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.	1413	equal to the passed C<now> value >>.
1366		1414
1367	This can be used to create very complex timers, such as a timer that	1415	This can be used to create very complex timers, such as a timer that
1368	triggers on each midnight, local time. To do this, you would calculate the	1416	triggers on "next midnight, local time". To do this, you would calculate the
1369	next midnight after C<now> and return the timestamp value for this. How	1417	next midnight after C<now> and return the timestamp value for this. How
1370	you do this is, again, up to you (but it is not trivial, which is the main	1418	you do this is, again, up to you (but it is not trivial, which is the main
1371	reason I omitted it as an example).	1419	reason I omitted it as an example).
1372		1420
1373	=back	1421	=back
…		…
1377	Simply stops and restarts the periodic watcher again. This is only useful	1425	Simply stops and restarts the periodic watcher again. This is only useful
1378	when you changed some parameters or the reschedule callback would return	1426	when you changed some parameters or the reschedule callback would return
1379	a different time than the last time it was called (e.g. in a crond like	1427	a different time than the last time it was called (e.g. in a crond like
1380	program when the crontabs have changed).	1428	program when the crontabs have changed).
1381		1429
		1430	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1431
		1432	When active, returns the absolute time that the watcher is supposed to
		1433	trigger next.
		1434
1382	=item ev_tstamp offset [read-write]	1435	=item ev_tstamp offset [read-write]
1383		1436
1384	When repeating, this contains the offset value, otherwise this is the	1437	When repeating, this contains the offset value, otherwise this is the
1385	absolute point in time (the C<at> value passed to C<ev_periodic_set>).	1438	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1386		1439
…		…
1397		1450
1398	The current reschedule callback, or C<0>, if this functionality is	1451	The current reschedule callback, or C<0>, if this functionality is
1399	switched off. Can be changed any time, but changes only take effect when	1452	switched off. Can be changed any time, but changes only take effect when
1400	the periodic timer fires or C<ev_periodic_again> is being called.	1453	the periodic timer fires or C<ev_periodic_again> is being called.
1401		1454
1402	=item ev_tstamp at [read-only]
1403
1404	When active, contains the absolute time that the watcher is supposed to
1405	trigger next.
1406
1407	=back	1455	=back
1408		1456
1409	=head3 Examples	1457	=head3 Examples
1410		1458
1411	Example: Call a callback every hour, or, more precisely, whenever the	1459	Example: Call a callback every hour, or, more precisely, whenever the
1412	system clock is divisible by 3600. The callback invocation times have	1460	system clock is divisible by 3600. The callback invocation times have
1413	potentially a lot of jittering, but good long-term stability.	1461	potentially a lot of jitter, but good long-term stability.
1414		1462
1415	static void	1463	static void
1416	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1464	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1417	{	1465	{
1418	... its now a full hour (UTC, or TAI or whatever your clock follows)	1466	... its now a full hour (UTC, or TAI or whatever your clock follows)
1419	}	1467	}
1420		1468
1421	struct ev_periodic hourly_tick;	1469	struct ev_periodic hourly_tick;
1422	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1470	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1423	ev_periodic_start (loop, &hourly_tick);	1471	ev_periodic_start (loop, &hourly_tick);
1424		1472
1425	Example: The same as above, but use a reschedule callback to do it:	1473	Example: The same as above, but use a reschedule callback to do it:
1426		1474
1427	#include <math.h>	1475	#include <math.h>
1428		1476
1429	static ev_tstamp	1477	static ev_tstamp
1430	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1478	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1431	{	1479	{
1432	return fmod (now, 3600.) + 3600.;	1480	return fmod (now, 3600.) + 3600.;
1433	}	1481	}
1434		1482
1435	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1483	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1436		1484
1437	Example: Call a callback every hour, starting now:	1485	Example: Call a callback every hour, starting now:
1438		1486
1439	struct ev_periodic hourly_tick;	1487	struct ev_periodic hourly_tick;
1440	ev_periodic_init (&hourly_tick, clock_cb,	1488	ev_periodic_init (&hourly_tick, clock_cb,
1441	fmod (ev_now (loop), 3600.), 3600., 0);	1489	fmod (ev_now (loop), 3600.), 3600., 0);
1442	ev_periodic_start (loop, &hourly_tick);	1490	ev_periodic_start (loop, &hourly_tick);
1443		1491
1444		1492
1445	=head2 C<ev_signal> - signal me when a signal gets signalled!	1493	=head2 C<ev_signal> - signal me when a signal gets signalled!
1446		1494
1447	Signal watchers will trigger an event when the process receives a specific	1495	Signal watchers will trigger an event when the process receives a specific
…		…
1455	as you don't register any with libev). Similarly, when the last signal	1503	as you don't register any with libev). Similarly, when the last signal
1456	watcher for a signal is stopped libev will reset the signal handler to	1504	watcher for a signal is stopped libev will reset the signal handler to
1457	SIG_DFL (regardless of what it was set to before).	1505	SIG_DFL (regardless of what it was set to before).
1458		1506
1459	If possible and supported, libev will install its handlers with	1507	If possible and supported, libev will install its handlers with
1460	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1508	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1461	interrupted. If you have a problem with syscalls getting interrupted by	1509	interrupted. If you have a problem with system calls getting interrupted by
1462	signals you can block all signals in an C<ev_check> watcher and unblock	1510	signals you can block all signals in an C<ev_check> watcher and unblock
1463	them in an C<ev_prepare> watcher.	1511	them in an C<ev_prepare> watcher.
1464		1512
1465	=head3 Watcher-Specific Functions and Data Members	1513	=head3 Watcher-Specific Functions and Data Members
1466		1514
…		…
1481		1529
1482	=head3 Examples	1530	=head3 Examples
1483		1531
1484	Example: Try to exit cleanly on SIGINT and SIGTERM.	1532	Example: Try to exit cleanly on SIGINT and SIGTERM.
1485		1533
1486	static void	1534	static void
1487	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1535	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1488	{	1536	{
1489	ev_unloop (loop, EVUNLOOP_ALL);	1537	ev_unloop (loop, EVUNLOOP_ALL);
1490	}	1538	}
1491		1539
1492	struct ev_signal signal_watcher;	1540	struct ev_signal signal_watcher;
1493	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1541	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1494	ev_signal_start (loop, &sigint_cb);	1542	ev_signal_start (loop, &sigint_cb);
1495		1543
1496		1544
1497	=head2 C<ev_child> - watch out for process status changes	1545	=head2 C<ev_child> - watch out for process status changes
1498		1546
1499	Child watchers trigger when your process receives a SIGCHLD in response to	1547	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1501	is permissible to install a child watcher I<after> the child has been	1549	is permissible to install a child watcher I<after> the child has been
1502	forked (which implies it might have already exited), as long as the event	1550	forked (which implies it might have already exited), as long as the event
1503	loop isn't entered (or is continued from a watcher).	1551	loop isn't entered (or is continued from a watcher).
1504		1552
1505	Only the default event loop is capable of handling signals, and therefore	1553	Only the default event loop is capable of handling signals, and therefore
1506	you can only rgeister child watchers in the default event loop.	1554	you can only register child watchers in the default event loop.
1507		1555
1508	=head3 Process Interaction	1556	=head3 Process Interaction
1509		1557
1510	Libev grabs C<SIGCHLD> as soon as the default event loop is	1558	Libev grabs C<SIGCHLD> as soon as the default event loop is
1511	initialised. This is necessary to guarantee proper behaviour even if	1559	initialised. This is necessary to guarantee proper behaviour even if
1512	the first child watcher is started after the child exits. The occurance	1560	the first child watcher is started after the child exits. The occurrence
1513	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1561	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1514	synchronously as part of the event loop processing. Libev always reaps all	1562	synchronously as part of the event loop processing. Libev always reaps all
1515	children, even ones not watched.	1563	children, even ones not watched.
1516		1564
1517	=head3 Overriding the Built-In Processing	1565	=head3 Overriding the Built-In Processing
…		…
1521	handler, you can override it easily by installing your own handler for	1569	handler, you can override it easily by installing your own handler for
1522	C<SIGCHLD> after initialising the default loop, and making sure the	1570	C<SIGCHLD> after initialising the default loop, and making sure the
1523	default loop never gets destroyed. You are encouraged, however, to use an	1571	default loop never gets destroyed. You are encouraged, however, to use an
1524	event-based approach to child reaping and thus use libev's support for	1572	event-based approach to child reaping and thus use libev's support for
1525	that, so other libev users can use C<ev_child> watchers freely.	1573	that, so other libev users can use C<ev_child> watchers freely.
		1574
		1575	=head3 Stopping the Child Watcher
		1576
		1577	Currently, the child watcher never gets stopped, even when the
		1578	child terminates, so normally one needs to stop the watcher in the
		1579	callback. Future versions of libev might stop the watcher automatically
		1580	when a child exit is detected.
1526		1581
1527	=head3 Watcher-Specific Functions and Data Members	1582	=head3 Watcher-Specific Functions and Data Members
1528		1583
1529	=over 4	1584	=over 4
1530		1585
…		…
1559	=head3 Examples	1614	=head3 Examples
1560		1615
1561	Example: C<fork()> a new process and install a child handler to wait for	1616	Example: C<fork()> a new process and install a child handler to wait for
1562	its completion.	1617	its completion.
1563		1618
1564	ev_child cw;	1619	ev_child cw;
1565		1620
1566	static void	1621	static void
1567	child_cb (EV_P_ struct ev_child *w, int revents)	1622	child_cb (EV_P_ struct ev_child *w, int revents)
1568	{	1623	{
1569	ev_child_stop (EV_A_ w);	1624	ev_child_stop (EV_A_ w);
1570	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1625	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1571	}	1626	}
1572		1627
1573	pid_t pid = fork ();	1628	pid_t pid = fork ();
1574		1629
1575	if (pid < 0)	1630	if (pid < 0)
1576	// error	1631	// error
1577	else if (pid == 0)	1632	else if (pid == 0)
1578	{	1633	{
1579	// the forked child executes here	1634	// the forked child executes here
1580	exit (1);	1635	exit (1);
1581	}	1636	}
1582	else	1637	else
1583	{	1638	{
1584	ev_child_init (&cw, child_cb, pid, 0);	1639	ev_child_init (&cw, child_cb, pid, 0);
1585	ev_child_start (EV_DEFAULT_ &cw);	1640	ev_child_start (EV_DEFAULT_ &cw);
1586	}	1641	}
1587		1642
1588		1643
1589	=head2 C<ev_stat> - did the file attributes just change?	1644	=head2 C<ev_stat> - did the file attributes just change?
1590		1645
1591	This watches a filesystem path for attribute changes. That is, it calls	1646	This watches a file system path for attribute changes. That is, it calls
1592	C<stat> regularly (or when the OS says it changed) and sees if it changed	1647	C<stat> regularly (or when the OS says it changed) and sees if it changed
1593	compared to the last time, invoking the callback if it did.	1648	compared to the last time, invoking the callback if it did.
1594		1649
1595	The path does not need to exist: changing from "path exists" to "path does	1650	The path does not need to exist: changing from "path exists" to "path does
1596	not exist" is a status change like any other. The condition "path does	1651	not exist" is a status change like any other. The condition "path does
…		…
1614	as even with OS-supported change notifications, this can be	1669	as even with OS-supported change notifications, this can be
1615	resource-intensive.	1670	resource-intensive.
1616		1671
1617	At the time of this writing, only the Linux inotify interface is	1672	At the time of this writing, only the Linux inotify interface is
1618	implemented (implementing kqueue support is left as an exercise for the	1673	implemented (implementing kqueue support is left as an exercise for the
		1674	reader, note, however, that the author sees no way of implementing ev_stat
1619	reader). Inotify will be used to give hints only and should not change the	1675	semantics with kqueue). Inotify will be used to give hints only and should
1620	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1676	not change the semantics of C<ev_stat> watchers, which means that libev
1621	to fall back to regular polling again even with inotify, but changes are	1677	sometimes needs to fall back to regular polling again even with inotify,
1622	usually detected immediately, and if the file exists there will be no	1678	but changes are usually detected immediately, and if the file exists there
1623	polling.	1679	will be no polling.
1624		1680
1625	=head3 ABI Issues (Largefile Support)	1681	=head3 ABI Issues (Largefile Support)
1626		1682
1627	Libev by default (unless the user overrides this) uses the default	1683	Libev by default (unless the user overrides this) uses the default
1628	compilation environment, which means that on systems with optionally	1684	compilation environment, which means that on systems with large file
1629	disabled large file support, you get the 32 bit version of the stat	1685	support disabled by default, you get the 32 bit version of the stat
1630	structure. When using the library from programs that change the ABI to	1686	structure. When using the library from programs that change the ABI to
1631	use 64 bit file offsets the programs will fail. In that case you have to	1687	use 64 bit file offsets the programs will fail. In that case you have to
1632	compile libev with the same flags to get binary compatibility. This is	1688	compile libev with the same flags to get binary compatibility. This is
1633	obviously the case with any flags that change the ABI, but the problem is	1689	obviously the case with any flags that change the ABI, but the problem is
1634	most noticably with ev_stat and largefile support.	1690	most noticeably disabled with ev_stat and large file support.
		1691
		1692	The solution for this is to lobby your distribution maker to make large
		1693	file interfaces available by default (as e.g. FreeBSD does) and not
		1694	optional. Libev cannot simply switch on large file support because it has
		1695	to exchange stat structures with application programs compiled using the
		1696	default compilation environment.
1635		1697
1636	=head3 Inotify	1698	=head3 Inotify
1637		1699
1638	When C<inotify (7)> support has been compiled into libev (generally only	1700	When C<inotify (7)> support has been compiled into libev (generally only
1639	available on Linux) and present at runtime, it will be used to speed up	1701	available on Linux) and present at runtime, it will be used to speed up
1640	change detection where possible. The inotify descriptor will be created lazily	1702	change detection where possible. The inotify descriptor will be created lazily
1641	when the first C<ev_stat> watcher is being started.	1703	when the first C<ev_stat> watcher is being started.
1642		1704
1643	Inotify presense does not change the semantics of C<ev_stat> watchers	1705	Inotify presence does not change the semantics of C<ev_stat> watchers
1644	except that changes might be detected earlier, and in some cases, to avoid	1706	except that changes might be detected earlier, and in some cases, to avoid
1645	making regular C<stat> calls. Even in the presense of inotify support	1707	making regular C<stat> calls. Even in the presence of inotify support
1646	there are many cases where libev has to resort to regular C<stat> polling.	1708	there are many cases where libev has to resort to regular C<stat> polling.
1647		1709
1648	(There is no support for kqueue, as apparently it cannot be used to	1710	(There is no support for kqueue, as apparently it cannot be used to
1649	implement this functionality, due to the requirement of having a file	1711	implement this functionality, due to the requirement of having a file
1650	descriptor open on the object at all times).	1712	descriptor open on the object at all times).
1651		1713
1652	=head3 The special problem of stat time resolution	1714	=head3 The special problem of stat time resolution
1653		1715
1654	The C<stat ()> syscall only supports full-second resolution portably, and	1716	The C<stat ()> system call only supports full-second resolution portably, and
1655	even on systems where the resolution is higher, many filesystems still	1717	even on systems where the resolution is higher, many file systems still
1656	only support whole seconds.	1718	only support whole seconds.
1657		1719
1658	That means that, if the time is the only thing that changes, you might	1720	That means that, if the time is the only thing that changes, you can
1659	miss updates: on the first update, C<ev_stat> detects a change and calls	1721	easily miss updates: on the first update, C<ev_stat> detects a change and
1660	your callback, which does something. When there is another update within	1722	calls your callback, which does something. When there is another update
1661	the same second, C<ev_stat> will be unable to detect it.	1723	within the same second, C<ev_stat> will be unable to detect it as the stat
		1724	data does not change.
1662		1725
1663	The solution to this is to delay acting on a change for a second (or till	1726	The solution to this is to delay acting on a change for slightly more
1664	the next second boundary), using a roughly one-second delay C<ev_timer>	1727	than a second (or till slightly after the next full second boundary), using
1665	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>	1728	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);
1666	is added to work around small timing inconsistencies of some operating	1729	ev_timer_again (loop, w)>).
1667	systems.	1730
		1731	The C<.02> offset is added to work around small timing inconsistencies
		1732	of some operating systems (where the second counter of the current time
		1733	might be be delayed. One such system is the Linux kernel, where a call to
		1734	C<gettimeofday> might return a timestamp with a full second later than
		1735	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1736	update file times then there will be a small window where the kernel uses
		1737	the previous second to update file times but libev might already execute
		1738	the timer callback).
1668		1739
1669	=head3 Watcher-Specific Functions and Data Members	1740	=head3 Watcher-Specific Functions and Data Members
1670		1741
1671	=over 4	1742	=over 4
1672		1743
…		…
1678	C<path>. The C<interval> is a hint on how quickly a change is expected to	1749	C<path>. The C<interval> is a hint on how quickly a change is expected to
1679	be detected and should normally be specified as C<0> to let libev choose	1750	be detected and should normally be specified as C<0> to let libev choose
1680	a suitable value. The memory pointed to by C<path> must point to the same	1751	a suitable value. The memory pointed to by C<path> must point to the same
1681	path for as long as the watcher is active.	1752	path for as long as the watcher is active.
1682		1753
1683	The callback will be receive C<EV_STAT> when a change was detected,	1754	The callback will receive C<EV_STAT> when a change was detected, relative
1684	relative to the attributes at the time the watcher was started (or the	1755	to the attributes at the time the watcher was started (or the last change
1685	last change was detected).	1756	was detected).
1686		1757
1687	=item ev_stat_stat (loop, ev_stat *)	1758	=item ev_stat_stat (loop, ev_stat *)
1688		1759
1689	Updates the stat buffer immediately with new values. If you change the	1760	Updates the stat buffer immediately with new values. If you change the
1690	watched path in your callback, you could call this fucntion to avoid	1761	watched path in your callback, you could call this function to avoid
1691	detecting this change (while introducing a race condition). Can also be	1762	detecting this change (while introducing a race condition if you are not
1692	useful simply to find out the new values.	1763	the only one changing the path). Can also be useful simply to find out the
		1764	new values.
1693		1765
1694	=item ev_statdata attr [read-only]	1766	=item ev_statdata attr [read-only]
1695		1767
1696	The most-recently detected attributes of the file. Although the type is of	1768	The most-recently detected attributes of the file. Although the type is
1697	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types	1769	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
1698	suitable for your system. If the C<st_nlink> member is C<0>, then there	1770	suitable for your system, but you can only rely on the POSIX-standardised
		1771	members to be present. If the C<st_nlink> member is C<0>, then there was
1699	was some error while C<stat>ing the file.	1772	some error while C<stat>ing the file.
1700		1773
1701	=item ev_statdata prev [read-only]	1774	=item ev_statdata prev [read-only]
1702		1775
1703	The previous attributes of the file. The callback gets invoked whenever	1776	The previous attributes of the file. The callback gets invoked whenever
1704	C<prev> != C<attr>.	1777	C<prev> != C<attr>, or, more precisely, one or more of these members
		1778	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1779	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1705		1780
1706	=item ev_tstamp interval [read-only]	1781	=item ev_tstamp interval [read-only]
1707		1782
1708	The specified interval.	1783	The specified interval.
1709		1784
1710	=item const char *path [read-only]	1785	=item const char *path [read-only]
1711		1786
1712	The filesystem path that is being watched.	1787	The file system path that is being watched.
1713		1788
1714	=back	1789	=back
1715		1790
1716	=head3 Examples	1791	=head3 Examples
1717		1792
1718	Example: Watch C</etc/passwd> for attribute changes.	1793	Example: Watch C</etc/passwd> for attribute changes.
1719		1794
1720	static void	1795	static void
1721	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1796	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1722	{	1797	{
1723	/* /etc/passwd changed in some way */	1798	/* /etc/passwd changed in some way */
1724	if (w->attr.st_nlink)	1799	if (w->attr.st_nlink)
1725	{	1800	{
1726	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1801	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1727	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1802	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1728	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1803	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1729	}	1804	}
1730	else	1805	else
1731	/* you shalt not abuse printf for puts */	1806	/* you shalt not abuse printf for puts */
1732	puts ("wow, /etc/passwd is not there, expect problems. "	1807	puts ("wow, /etc/passwd is not there, expect problems. "
1733	"if this is windows, they already arrived\n");	1808	"if this is windows, they already arrived\n");
1734	}	1809	}
1735		1810
1736	...	1811	...
1737	ev_stat passwd;	1812	ev_stat passwd;
1738		1813
1739	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1814	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1740	ev_stat_start (loop, &passwd);	1815	ev_stat_start (loop, &passwd);
1741		1816
1742	Example: Like above, but additionally use a one-second delay so we do not	1817	Example: Like above, but additionally use a one-second delay so we do not
1743	miss updates (however, frequent updates will delay processing, too, so	1818	miss updates (however, frequent updates will delay processing, too, so
1744	one might do the work both on C<ev_stat> callback invocation I<and> on	1819	one might do the work both on C<ev_stat> callback invocation I<and> on
1745	C<ev_timer> callback invocation).	1820	C<ev_timer> callback invocation).
1746		1821
1747	static ev_stat passwd;	1822	static ev_stat passwd;
1748	static ev_timer timer;	1823	static ev_timer timer;
1749		1824
1750	static void	1825	static void
1751	timer_cb (EV_P_ ev_timer *w, int revents)	1826	timer_cb (EV_P_ ev_timer *w, int revents)
1752	{	1827	{
1753	ev_timer_stop (EV_A_ w);	1828	ev_timer_stop (EV_A_ w);
1754		1829
1755	/* now it's one second after the most recent passwd change */	1830	/* now it's one second after the most recent passwd change */
1756	}	1831	}
1757		1832
1758	static void	1833	static void
1759	stat_cb (EV_P_ ev_stat *w, int revents)	1834	stat_cb (EV_P_ ev_stat *w, int revents)
1760	{	1835	{
1761	/* reset the one-second timer */	1836	/* reset the one-second timer */
1762	ev_timer_again (EV_A_ &timer);	1837	ev_timer_again (EV_A_ &timer);
1763	}	1838	}
1764		1839
1765	...	1840	...
1766	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1841	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1767	ev_stat_start (loop, &passwd);	1842	ev_stat_start (loop, &passwd);
1768	ev_timer_init (&timer, timer_cb, 0., 1.01);	1843	ev_timer_init (&timer, timer_cb, 0., 1.02);
1769		1844
1770		1845
1771	=head2 C<ev_idle> - when you've got nothing better to do...	1846	=head2 C<ev_idle> - when you've got nothing better to do...
1772		1847
1773	Idle watchers trigger events when no other events of the same or higher	1848	Idle watchers trigger events when no other events of the same or higher
…		…
1804	=head3 Examples	1879	=head3 Examples
1805		1880
1806	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1881	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1807	callback, free it. Also, use no error checking, as usual.	1882	callback, free it. Also, use no error checking, as usual.
1808		1883
1809	static void	1884	static void
1810	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1885	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1811	{	1886	{
1812	free (w);	1887	free (w);
1813	// now do something you wanted to do when the program has	1888	// now do something you wanted to do when the program has
1814	// no longer anything immediate to do.	1889	// no longer anything immediate to do.
1815	}	1890	}
1816		1891
1817	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1892	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1818	ev_idle_init (idle_watcher, idle_cb);	1893	ev_idle_init (idle_watcher, idle_cb);
1819	ev_idle_start (loop, idle_cb);	1894	ev_idle_start (loop, idle_cb);
1820		1895
1821		1896
1822	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1897	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1823		1898
1824	Prepare and check watchers are usually (but not always) used in tandem:	1899	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1843		1918
1844	This is done by examining in each prepare call which file descriptors need	1919	This is done by examining in each prepare call which file descriptors need
1845	to be watched by the other library, registering C<ev_io> watchers for	1920	to be watched by the other library, registering C<ev_io> watchers for
1846	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1921	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1847	provide just this functionality). Then, in the check watcher you check for	1922	provide just this functionality). Then, in the check watcher you check for
1848	any events that occured (by checking the pending status of all watchers	1923	any events that occurred (by checking the pending status of all watchers
1849	and stopping them) and call back into the library. The I/O and timer	1924	and stopping them) and call back into the library. The I/O and timer
1850	callbacks will never actually be called (but must be valid nevertheless,	1925	callbacks will never actually be called (but must be valid nevertheless,
1851	because you never know, you know?).	1926	because you never know, you know?).
1852		1927
1853	As another example, the Perl Coro module uses these hooks to integrate	1928	As another example, the Perl Coro module uses these hooks to integrate
…		…
1861		1936
1862	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1937	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
1863	priority, to ensure that they are being run before any other watchers	1938	priority, to ensure that they are being run before any other watchers
1864	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,	1939	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
1865	too) should not activate ("feed") events into libev. While libev fully	1940	too) should not activate ("feed") events into libev. While libev fully
1866	supports this, they will be called before other C<ev_check> watchers	1941	supports this, they might get executed before other C<ev_check> watchers
1867	did their job. As C<ev_check> watchers are often used to embed other	1942	did their job. As C<ev_check> watchers are often used to embed other
1868	(non-libev) event loops those other event loops might be in an unusable	1943	(non-libev) event loops those other event loops might be in an unusable
1869	state until their C<ev_check> watcher ran (always remind yourself to	1944	state until their C<ev_check> watcher ran (always remind yourself to
1870	coexist peacefully with others).	1945	coexist peacefully with others).
1871		1946
…		…
1886	=head3 Examples	1961	=head3 Examples
1887		1962
1888	There are a number of principal ways to embed other event loops or modules	1963	There are a number of principal ways to embed other event loops or modules
1889	into libev. Here are some ideas on how to include libadns into libev	1964	into libev. Here are some ideas on how to include libadns into libev
1890	(there is a Perl module named C<EV::ADNS> that does this, which you could	1965	(there is a Perl module named C<EV::ADNS> that does this, which you could
1891	use for an actually working example. Another Perl module named C<EV::Glib>	1966	use as a working example. Another Perl module named C<EV::Glib> embeds a
1892	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV	1967	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1893	into the Glib event loop).	1968	Glib event loop).
1894		1969
1895	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	1970	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1896	and in a check watcher, destroy them and call into libadns. What follows	1971	and in a check watcher, destroy them and call into libadns. What follows
1897	is pseudo-code only of course. This requires you to either use a low	1972	is pseudo-code only of course. This requires you to either use a low
1898	priority for the check watcher or use C<ev_clear_pending> explicitly, as	1973	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1899	the callbacks for the IO/timeout watchers might not have been called yet.	1974	the callbacks for the IO/timeout watchers might not have been called yet.
1900		1975
1901	static ev_io iow [nfd];	1976	static ev_io iow [nfd];
1902	static ev_timer tw;	1977	static ev_timer tw;
1903		1978
1904	static void	1979	static void
1905	io_cb (ev_loop *loop, ev_io *w, int revents)	1980	io_cb (ev_loop *loop, ev_io *w, int revents)
1906	{	1981	{
1907	}	1982	}
1908		1983
1909	// create io watchers for each fd and a timer before blocking	1984	// create io watchers for each fd and a timer before blocking
1910	static void	1985	static void
1911	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1986	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1912	{	1987	{
1913	int timeout = 3600000;	1988	int timeout = 3600000;
1914	struct pollfd fds [nfd];	1989	struct pollfd fds [nfd];
1915	// actual code will need to loop here and realloc etc.	1990	// actual code will need to loop here and realloc etc.
1916	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1991	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1917		1992
1918	/* the callback is illegal, but won't be called as we stop during check */	1993	/* the callback is illegal, but won't be called as we stop during check */
1919	ev_timer_init (&tw, 0, timeout * 1e-3);	1994	ev_timer_init (&tw, 0, timeout * 1e-3);
1920	ev_timer_start (loop, &tw);	1995	ev_timer_start (loop, &tw);
1921		1996
1922	// create one ev_io per pollfd	1997	// create one ev_io per pollfd
1923	for (int i = 0; i < nfd; ++i)	1998	for (int i = 0; i < nfd; ++i)
1924	{	1999	{
1925	ev_io_init (iow + i, io_cb, fds [i].fd,	2000	ev_io_init (iow + i, io_cb, fds [i].fd,
1926	((fds [i].events & POLLIN ? EV_READ : 0)	2001	((fds [i].events & POLLIN ? EV_READ : 0)
1927	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	2002	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1928		2003
1929	fds [i].revents = 0;	2004	fds [i].revents = 0;
1930	ev_io_start (loop, iow + i);	2005	ev_io_start (loop, iow + i);
1931	}	2006	}
1932	}	2007	}
1933		2008
1934	// stop all watchers after blocking	2009	// stop all watchers after blocking
1935	static void	2010	static void
1936	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	2011	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1937	{	2012	{
1938	ev_timer_stop (loop, &tw);	2013	ev_timer_stop (loop, &tw);
1939		2014
1940	for (int i = 0; i < nfd; ++i)	2015	for (int i = 0; i < nfd; ++i)
1941	{	2016	{
1942	// set the relevant poll flags	2017	// set the relevant poll flags
1943	// could also call adns_processreadable etc. here	2018	// could also call adns_processreadable etc. here
1944	struct pollfd *fd = fds + i;	2019	struct pollfd *fd = fds + i;
1945	int revents = ev_clear_pending (iow + i);	2020	int revents = ev_clear_pending (iow + i);
1946	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	2021	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1947	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	2022	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1948		2023
1949	// now stop the watcher	2024	// now stop the watcher
1950	ev_io_stop (loop, iow + i);	2025	ev_io_stop (loop, iow + i);
1951	}	2026	}
1952		2027
1953	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2028	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1954	}	2029	}
1955		2030
1956	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2031	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
1957	in the prepare watcher and would dispose of the check watcher.	2032	in the prepare watcher and would dispose of the check watcher.
1958		2033
1959	Method 3: If the module to be embedded supports explicit event	2034	Method 3: If the module to be embedded supports explicit event
1960	notification (adns does), you can also make use of the actual watcher	2035	notification (libadns does), you can also make use of the actual watcher
1961	callbacks, and only destroy/create the watchers in the prepare watcher.	2036	callbacks, and only destroy/create the watchers in the prepare watcher.
1962		2037
1963	static void	2038	static void
1964	timer_cb (EV_P_ ev_timer *w, int revents)	2039	timer_cb (EV_P_ ev_timer *w, int revents)
1965	{	2040	{
1966	adns_state ads = (adns_state)w->data;	2041	adns_state ads = (adns_state)w->data;
1967	update_now (EV_A);	2042	update_now (EV_A);
1968		2043
1969	adns_processtimeouts (ads, &tv_now);	2044	adns_processtimeouts (ads, &tv_now);
1970	}	2045	}
1971		2046
1972	static void	2047	static void
1973	io_cb (EV_P_ ev_io *w, int revents)	2048	io_cb (EV_P_ ev_io *w, int revents)
1974	{	2049	{
1975	adns_state ads = (adns_state)w->data;	2050	adns_state ads = (adns_state)w->data;
1976	update_now (EV_A);	2051	update_now (EV_A);
1977		2052
1978	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2053	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1979	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2054	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1980	}	2055	}
1981		2056
1982	// do not ever call adns_afterpoll	2057	// do not ever call adns_afterpoll
1983		2058
1984	Method 4: Do not use a prepare or check watcher because the module you	2059	Method 4: Do not use a prepare or check watcher because the module you
1985	want to embed is too inflexible to support it. Instead, youc na override	2060	want to embed is too inflexible to support it. Instead, you can override
1986	their poll function. The drawback with this solution is that the main	2061	their poll function. The drawback with this solution is that the main
1987	loop is now no longer controllable by EV. The C<Glib::EV> module does	2062	loop is now no longer controllable by EV. The C<Glib::EV> module does
1988	this.	2063	this.
1989		2064
1990	static gint	2065	static gint
1991	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2066	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1992	{	2067	{
1993	int got_events = 0;	2068	int got_events = 0;
1994		2069
1995	for (n = 0; n < nfds; ++n)	2070	for (n = 0; n < nfds; ++n)
1996	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2071	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1997		2072
1998	if (timeout >= 0)	2073	if (timeout >= 0)
1999	// create/start timer	2074	// create/start timer
2000		2075
2001	// poll	2076	// poll
2002	ev_loop (EV_A_ 0);	2077	ev_loop (EV_A_ 0);
2003		2078
2004	// stop timer again	2079	// stop timer again
2005	if (timeout >= 0)	2080	if (timeout >= 0)
2006	ev_timer_stop (EV_A_ &to);	2081	ev_timer_stop (EV_A_ &to);
2007		2082
2008	// stop io watchers again - their callbacks should have set	2083	// stop io watchers again - their callbacks should have set
2009	for (n = 0; n < nfds; ++n)	2084	for (n = 0; n < nfds; ++n)
2010	ev_io_stop (EV_A_ iow [n]);	2085	ev_io_stop (EV_A_ iow [n]);
2011		2086
2012	return got_events;	2087	return got_events;
2013	}	2088	}
2014		2089
2015		2090
2016	=head2 C<ev_embed> - when one backend isn't enough...	2091	=head2 C<ev_embed> - when one backend isn't enough...
2017		2092
2018	This is a rather advanced watcher type that lets you embed one event loop	2093	This is a rather advanced watcher type that lets you embed one event loop
…		…
2074		2149
2075	Configures the watcher to embed the given loop, which must be	2150	Configures the watcher to embed the given loop, which must be
2076	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be	2151	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
2077	invoked automatically, otherwise it is the responsibility of the callback	2152	invoked automatically, otherwise it is the responsibility of the callback
2078	to invoke it (it will continue to be called until the sweep has been done,	2153	to invoke it (it will continue to be called until the sweep has been done,
2079	if you do not want thta, you need to temporarily stop the embed watcher).	2154	if you do not want that, you need to temporarily stop the embed watcher).
2080		2155
2081	=item ev_embed_sweep (loop, ev_embed *)	2156	=item ev_embed_sweep (loop, ev_embed *)
2082		2157
2083	Make a single, non-blocking sweep over the embedded loop. This works	2158	Make a single, non-blocking sweep over the embedded loop. This works
2084	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2159	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2085	apropriate way for embedded loops.	2160	appropriate way for embedded loops.
2086		2161
2087	=item struct ev_loop *other [read-only]	2162	=item struct ev_loop *other [read-only]
2088		2163
2089	The embedded event loop.	2164	The embedded event loop.
2090		2165
…		…
2092		2167
2093	=head3 Examples	2168	=head3 Examples
2094		2169
2095	Example: Try to get an embeddable event loop and embed it into the default	2170	Example: Try to get an embeddable event loop and embed it into the default
2096	event loop. If that is not possible, use the default loop. The default	2171	event loop. If that is not possible, use the default loop. The default
2097	loop is stored in C<loop_hi>, while the mebeddable loop is stored in	2172	loop is stored in C<loop_hi>, while the embeddable loop is stored in
2098	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be	2173	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2099	used).	2174	used).
2100		2175
2101	struct ev_loop *loop_hi = ev_default_init (0);	2176	struct ev_loop *loop_hi = ev_default_init (0);
2102	struct ev_loop *loop_lo = 0;	2177	struct ev_loop *loop_lo = 0;
2103	struct ev_embed embed;	2178	struct ev_embed embed;
2104		2179
2105	// see if there is a chance of getting one that works	2180	// see if there is a chance of getting one that works
2106	// (remember that a flags value of 0 means autodetection)	2181	// (remember that a flags value of 0 means autodetection)
2107	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2182	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2108	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2183	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2109	: 0;	2184	: 0;
2110		2185
2111	// if we got one, then embed it, otherwise default to loop_hi	2186	// if we got one, then embed it, otherwise default to loop_hi
2112	if (loop_lo)	2187	if (loop_lo)
2113	{	2188	{
2114	ev_embed_init (&embed, 0, loop_lo);	2189	ev_embed_init (&embed, 0, loop_lo);
2115	ev_embed_start (loop_hi, &embed);	2190	ev_embed_start (loop_hi, &embed);
2116	}	2191	}
2117	else	2192	else
2118	loop_lo = loop_hi;	2193	loop_lo = loop_hi;
2119		2194
2120	Example: Check if kqueue is available but not recommended and create	2195	Example: Check if kqueue is available but not recommended and create
2121	a kqueue backend for use with sockets (which usually work with any	2196	a kqueue backend for use with sockets (which usually work with any
2122	kqueue implementation). Store the kqueue/socket-only event loop in	2197	kqueue implementation). Store the kqueue/socket-only event loop in
2123	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2198	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2124		2199
2125	struct ev_loop *loop = ev_default_init (0);	2200	struct ev_loop *loop = ev_default_init (0);
2126	struct ev_loop *loop_socket = 0;	2201	struct ev_loop *loop_socket = 0;
2127	struct ev_embed embed;	2202	struct ev_embed embed;
2128		2203
2129	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2204	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2130	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2205	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2131	{	2206	{
2132	ev_embed_init (&embed, 0, loop_socket);	2207	ev_embed_init (&embed, 0, loop_socket);
2133	ev_embed_start (loop, &embed);	2208	ev_embed_start (loop, &embed);
2134	}	2209	}
2135		2210
2136	if (!loop_socket)	2211	if (!loop_socket)
2137	loop_socket = loop;	2212	loop_socket = loop;
2138		2213
2139	// now use loop_socket for all sockets, and loop for everything else	2214	// now use loop_socket for all sockets, and loop for everything else
2140		2215
2141		2216
2142	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2217	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2143		2218
2144	Fork watchers are called when a C<fork ()> was detected (usually because	2219	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2197		2272
2198	=item queueing from a signal handler context	2273	=item queueing from a signal handler context
2199		2274
2200	To implement race-free queueing, you simply add to the queue in the signal	2275	To implement race-free queueing, you simply add to the queue in the signal
2201	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2276	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2202	some fictitiuous SIGUSR1 handler:	2277	some fictitious SIGUSR1 handler:
2203		2278
2204	static ev_async mysig;	2279	static ev_async mysig;
2205		2280
2206	static void	2281	static void
2207	sigusr1_handler (void)	2282	sigusr1_handler (void)
…		…
2281	=item ev_async_send (loop, ev_async *)	2356	=item ev_async_send (loop, ev_async *)
2282		2357
2283	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2358	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2284	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2359	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2285	C<ev_feed_event>, this call is safe to do in other threads, signal or	2360	C<ev_feed_event>, this call is safe to do in other threads, signal or
2286	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding	2361	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2287	section below on what exactly this means).	2362	section below on what exactly this means).
2288		2363
2289	This call incurs the overhead of a syscall only once per loop iteration,	2364	This call incurs the overhead of a system call only once per loop iteration,
2290	so while the overhead might be noticable, it doesn't apply to repeated	2365	so while the overhead might be noticeable, it doesn't apply to repeated
2291	calls to C<ev_async_send>.	2366	calls to C<ev_async_send>.
2292		2367
2293	=item bool = ev_async_pending (ev_async *)	2368	=item bool = ev_async_pending (ev_async *)
2294		2369
2295	Returns a non-zero value when C<ev_async_send> has been called on the	2370	Returns a non-zero value when C<ev_async_send> has been called on the
…		…
2297	event loop.	2372	event loop.
2298		2373
2299	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When	2374	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
2300	the loop iterates next and checks for the watcher to have become active,	2375	the loop iterates next and checks for the watcher to have become active,
2301	it will reset the flag again. C<ev_async_pending> can be used to very	2376	it will reset the flag again. C<ev_async_pending> can be used to very
2302	quickly check wether invoking the loop might be a good idea.	2377	quickly check whether invoking the loop might be a good idea.
2303		2378
2304	Not that this does I<not> check wether the watcher itself is pending, only	2379	Not that this does I<not> check whether the watcher itself is pending, only
2305	wether it has been requested to make this watcher pending.	2380	whether it has been requested to make this watcher pending.
2306		2381
2307	=back	2382	=back
2308		2383
2309		2384
2310	=head1 OTHER FUNCTIONS	2385	=head1 OTHER FUNCTIONS
…		…
2321	or timeout without having to allocate/configure/start/stop/free one or	2396	or timeout without having to allocate/configure/start/stop/free one or
2322	more watchers yourself.	2397	more watchers yourself.
2323		2398
2324	If C<fd> is less than 0, then no I/O watcher will be started and events	2399	If C<fd> is less than 0, then no I/O watcher will be started and events
2325	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2400	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2326	C<events> set will be craeted and started.	2401	C<events> set will be created and started.
2327		2402
2328	If C<timeout> is less than 0, then no timeout watcher will be	2403	If C<timeout> is less than 0, then no timeout watcher will be
2329	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2404	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2330	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2405	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2331	dubious value.	2406	dubious value.
…		…
2333	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2408	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2334	passed an C<revents> set like normal event callbacks (a combination of	2409	passed an C<revents> set like normal event callbacks (a combination of
2335	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2410	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2336	value passed to C<ev_once>:	2411	value passed to C<ev_once>:
2337		2412
2338	static void stdin_ready (int revents, void *arg)	2413	static void stdin_ready (int revents, void *arg)
2339	{	2414	{
2340	if (revents & EV_TIMEOUT)	2415	if (revents & EV_TIMEOUT)
2341	/* doh, nothing entered */;	2416	/* doh, nothing entered */;
2342	else if (revents & EV_READ)	2417	else if (revents & EV_READ)
2343	/* stdin might have data for us, joy! */;	2418	/* stdin might have data for us, joy! */;
2344	}	2419	}
2345		2420
2346	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2421	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2347		2422
2348	=item ev_feed_event (ev_loop *, watcher *, int revents)	2423	=item ev_feed_event (ev_loop *, watcher *, int revents)
2349		2424
2350	Feeds the given event set into the event loop, as if the specified event	2425	Feeds the given event set into the event loop, as if the specified event
2351	had happened for the specified watcher (which must be a pointer to an	2426	had happened for the specified watcher (which must be a pointer to an
…		…
2356	Feed an event on the given fd, as if a file descriptor backend detected	2431	Feed an event on the given fd, as if a file descriptor backend detected
2357	the given events it.	2432	the given events it.
2358		2433
2359	=item ev_feed_signal_event (ev_loop *loop, int signum)	2434	=item ev_feed_signal_event (ev_loop *loop, int signum)
2360		2435
2361	Feed an event as if the given signal occured (C<loop> must be the default	2436	Feed an event as if the given signal occurred (C<loop> must be the default
2362	loop!).	2437	loop!).
2363		2438
2364	=back	2439	=back
2365		2440
2366		2441
…		…
2382		2457
2383	=item * Priorities are not currently supported. Initialising priorities	2458	=item * Priorities are not currently supported. Initialising priorities
2384	will fail and all watchers will have the same priority, even though there	2459	will fail and all watchers will have the same priority, even though there
2385	is an ev_pri field.	2460	is an ev_pri field.
2386		2461
		2462	=item * In libevent, the last base created gets the signals, in libev, the
		2463	first base created (== the default loop) gets the signals.
		2464
2387	=item * Other members are not supported.	2465	=item * Other members are not supported.
2388		2466
2389	=item * The libev emulation is I<not> ABI compatible to libevent, you need	2467	=item * The libev emulation is I<not> ABI compatible to libevent, you need
2390	to use the libev header file and library.	2468	to use the libev header file and library.
2391		2469
2392	=back	2470	=back
2393		2471
2394	=head1 C++ SUPPORT	2472	=head1 C++ SUPPORT
2395		2473
2396	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2474	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2397	you to use some convinience methods to start/stop watchers and also change	2475	you to use some convenience methods to start/stop watchers and also change
2398	the callback model to a model using method callbacks on objects.	2476	the callback model to a model using method callbacks on objects.
2399		2477
2400	To use it,	2478	To use it,
2401		2479
2402	#include <ev++.h>	2480	#include <ev++.h>
2403		2481
2404	This automatically includes F<ev.h> and puts all of its definitions (many	2482	This automatically includes F<ev.h> and puts all of its definitions (many
2405	of them macros) into the global namespace. All C++ specific things are	2483	of them macros) into the global namespace. All C++ specific things are
2406	put into the C<ev> namespace. It should support all the same embedding	2484	put into the C<ev> namespace. It should support all the same embedding
2407	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2485	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2474	your compiler is good :), then the method will be fully inlined into the	2552	your compiler is good :), then the method will be fully inlined into the
2475	thunking function, making it as fast as a direct C callback.	2553	thunking function, making it as fast as a direct C callback.
2476		2554
2477	Example: simple class declaration and watcher initialisation	2555	Example: simple class declaration and watcher initialisation
2478		2556
2479	struct myclass	2557	struct myclass
2480	{	2558	{
2481	void io_cb (ev::io &w, int revents) { }	2559	void io_cb (ev::io &w, int revents) { }
2482	}	2560	}
2483		2561
2484	myclass obj;	2562	myclass obj;
2485	ev::io iow;	2563	ev::io iow;
2486	iow.set <myclass, &myclass::io_cb> (&obj);	2564	iow.set <myclass, &myclass::io_cb> (&obj);
2487		2565
2488	=item w->set<function> (void *data = 0)	2566	=item w->set<function> (void *data = 0)
2489		2567
2490	Also sets a callback, but uses a static method or plain function as	2568	Also sets a callback, but uses a static method or plain function as
2491	callback. The optional C<data> argument will be stored in the watcher's	2569	callback. The optional C<data> argument will be stored in the watcher's
…		…
2495		2573
2496	See the method-C<set> above for more details.	2574	See the method-C<set> above for more details.
2497		2575
2498	Example:	2576	Example:
2499		2577
2500	static void io_cb (ev::io &w, int revents) { }	2578	static void io_cb (ev::io &w, int revents) { }
2501	iow.set <io_cb> ();	2579	iow.set <io_cb> ();
2502		2580
2503	=item w->set (struct ev_loop *)	2581	=item w->set (struct ev_loop *)
2504		2582
2505	Associates a different C<struct ev_loop> with this watcher. You can only	2583	Associates a different C<struct ev_loop> with this watcher. You can only
2506	do this when the watcher is inactive (and not pending either).	2584	do this when the watcher is inactive (and not pending either).
2507		2585
2508	=item w->set ([args])	2586	=item w->set ([arguments])
2509		2587
2510	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2588	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2511	called at least once. Unlike the C counterpart, an active watcher gets	2589	called at least once. Unlike the C counterpart, an active watcher gets
2512	automatically stopped and restarted when reconfiguring it with this	2590	automatically stopped and restarted when reconfiguring it with this
2513	method.	2591	method.
2514		2592
2515	=item w->start ()	2593	=item w->start ()
…		…
2539	=back	2617	=back
2540		2618
2541	Example: Define a class with an IO and idle watcher, start one of them in	2619	Example: Define a class with an IO and idle watcher, start one of them in
2542	the constructor.	2620	the constructor.
2543		2621
2544	class myclass	2622	class myclass
2545	{	2623	{
2546	ev::io io; void io_cb (ev::io &w, int revents);	2624	ev::io io; void io_cb (ev::io &w, int revents);
2547	ev:idle idle void idle_cb (ev::idle &w, int revents);	2625	ev:idle idle void idle_cb (ev::idle &w, int revents);
2548		2626
2549	myclass (int fd)	2627	myclass (int fd)
2550	{	2628	{
2551	io .set <myclass, &myclass::io_cb > (this);	2629	io .set <myclass, &myclass::io_cb > (this);
2552	idle.set <myclass, &myclass::idle_cb> (this);	2630	idle.set <myclass, &myclass::idle_cb> (this);
2553		2631
2554	io.start (fd, ev::READ);	2632	io.start (fd, ev::READ);
2555	}	2633	}
2556	};	2634	};
2557		2635
2558		2636
2559	=head1 OTHER LANGUAGE BINDINGS	2637	=head1 OTHER LANGUAGE BINDINGS
2560		2638
2561	Libev does not offer other language bindings itself, but bindings for a	2639	Libev does not offer other language bindings itself, but bindings for a
2562	numbe rof languages exist in the form of third-party packages. If you know	2640	number of languages exist in the form of third-party packages. If you know
2563	any interesting language binding in addition to the ones listed here, drop	2641	any interesting language binding in addition to the ones listed here, drop
2564	me a note.	2642	me a note.
2565		2643
2566	=over 4	2644	=over 4
2567		2645
…		…
2571	libev. EV is developed together with libev. Apart from the EV core module,	2649	libev. EV is developed together with libev. Apart from the EV core module,
2572	there are additional modules that implement libev-compatible interfaces	2650	there are additional modules that implement libev-compatible interfaces
2573	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the	2651	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
2574	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).	2652	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2575		2653
2576	It can be found and installed via CPAN, its homepage is found at	2654	It can be found and installed via CPAN, its homepage is at
2577	L<http://software.schmorp.de/pkg/EV>.	2655	L<http://software.schmorp.de/pkg/EV>.
2578		2656
		2657	=item Python
		2658
		2659	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2660	seems to be quite complete and well-documented. Note, however, that the
		2661	patch they require for libev is outright dangerous as it breaks the ABI
		2662	for everybody else, and therefore, should never be applied in an installed
		2663	libev (if python requires an incompatible ABI then it needs to embed
		2664	libev).
		2665
2579	=item Ruby	2666	=item Ruby
2580		2667
2581	Tony Arcieri has written a ruby extension that offers access to a subset	2668	Tony Arcieri has written a ruby extension that offers access to a subset
2582	of the libev API and adds filehandle abstractions, asynchronous DNS and	2669	of the libev API and adds file handle abstractions, asynchronous DNS and
2583	more on top of it. It can be found via gem servers. Its homepage is at	2670	more on top of it. It can be found via gem servers. Its homepage is at
2584	L<http://rev.rubyforge.org/>.	2671	L<http://rev.rubyforge.org/>.
2585		2672
2586	=item D	2673	=item D
2587		2674
2588	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	2675	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
2589	be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.	2676	be found at L<http://proj.llucax.com.ar/wiki/evd>.
2590		2677
2591	=back	2678	=back
2592		2679
2593		2680
2594	=head1 MACRO MAGIC	2681	=head1 MACRO MAGIC
2595		2682
2596	Libev can be compiled with a variety of options, the most fundamantal	2683	Libev can be compiled with a variety of options, the most fundamental
2597	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2684	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2598	functions and callbacks have an initial C<struct ev_loop *> argument.	2685	functions and callbacks have an initial C<struct ev_loop *> argument.
2599		2686
2600	To make it easier to write programs that cope with either variant, the	2687	To make it easier to write programs that cope with either variant, the
2601	following macros are defined:	2688	following macros are defined:
…		…
2606		2693
2607	This provides the loop I<argument> for functions, if one is required ("ev	2694	This provides the loop I<argument> for functions, if one is required ("ev
2608	loop argument"). The C<EV_A> form is used when this is the sole argument,	2695	loop argument"). The C<EV_A> form is used when this is the sole argument,
2609	C<EV_A_> is used when other arguments are following. Example:	2696	C<EV_A_> is used when other arguments are following. Example:
2610		2697
2611	ev_unref (EV_A);	2698	ev_unref (EV_A);
2612	ev_timer_add (EV_A_ watcher);	2699	ev_timer_add (EV_A_ watcher);
2613	ev_loop (EV_A_ 0);	2700	ev_loop (EV_A_ 0);
2614		2701
2615	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2702	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2616	which is often provided by the following macro.	2703	which is often provided by the following macro.
2617		2704
2618	=item C<EV_P>, C<EV_P_>	2705	=item C<EV_P>, C<EV_P_>
2619		2706
2620	This provides the loop I<parameter> for functions, if one is required ("ev	2707	This provides the loop I<parameter> for functions, if one is required ("ev
2621	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2708	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2622	C<EV_P_> is used when other parameters are following. Example:	2709	C<EV_P_> is used when other parameters are following. Example:
2623		2710
2624	// this is how ev_unref is being declared	2711	// this is how ev_unref is being declared
2625	static void ev_unref (EV_P);	2712	static void ev_unref (EV_P);
2626		2713
2627	// this is how you can declare your typical callback	2714	// this is how you can declare your typical callback
2628	static void cb (EV_P_ ev_timer *w, int revents)	2715	static void cb (EV_P_ ev_timer *w, int revents)
2629		2716
2630	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2717	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2631	suitable for use with C<EV_A>.	2718	suitable for use with C<EV_A>.
2632		2719
2633	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2720	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
2634		2721
2635	Similar to the other two macros, this gives you the value of the default	2722	Similar to the other two macros, this gives you the value of the default
2636	loop, if multiple loops are supported ("ev loop default").	2723	loop, if multiple loops are supported ("ev loop default").
		2724
		2725	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
		2726
		2727	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
		2728	default loop has been initialised (C<UC> == unchecked). Their behaviour
		2729	is undefined when the default loop has not been initialised by a previous
		2730	execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
		2731
		2732	It is often prudent to use C<EV_DEFAULT> when initialising the first
		2733	watcher in a function but use C<EV_DEFAULT_UC> afterwards.
2637		2734
2638	=back	2735	=back
2639		2736
2640	Example: Declare and initialise a check watcher, utilising the above	2737	Example: Declare and initialise a check watcher, utilising the above
2641	macros so it will work regardless of whether multiple loops are supported	2738	macros so it will work regardless of whether multiple loops are supported
2642	or not.	2739	or not.
2643		2740
2644	static void	2741	static void
2645	check_cb (EV_P_ ev_timer *w, int revents)	2742	check_cb (EV_P_ ev_timer *w, int revents)
2646	{	2743	{
2647	ev_check_stop (EV_A_ w);	2744	ev_check_stop (EV_A_ w);
2648	}	2745	}
2649		2746
2650	ev_check check;	2747	ev_check check;
2651	ev_check_init (&check, check_cb);	2748	ev_check_init (&check, check_cb);
2652	ev_check_start (EV_DEFAULT_ &check);	2749	ev_check_start (EV_DEFAULT_ &check);
2653	ev_loop (EV_DEFAULT_ 0);	2750	ev_loop (EV_DEFAULT_ 0);
2654		2751
2655	=head1 EMBEDDING	2752	=head1 EMBEDDING
2656		2753
2657	Libev can (and often is) directly embedded into host	2754	Libev can (and often is) directly embedded into host
2658	applications. Examples of applications that embed it include the Deliantra	2755	applications. Examples of applications that embed it include the Deliantra
…		…
2665	libev somewhere in your source tree).	2762	libev somewhere in your source tree).
2666		2763
2667	=head2 FILESETS	2764	=head2 FILESETS
2668		2765
2669	Depending on what features you need you need to include one or more sets of files	2766	Depending on what features you need you need to include one or more sets of files
2670	in your app.	2767	in your application.
2671		2768
2672	=head3 CORE EVENT LOOP	2769	=head3 CORE EVENT LOOP
2673		2770
2674	To include only the libev core (all the C<ev_*> functions), with manual	2771	To include only the libev core (all the C<ev_*> functions), with manual
2675	configuration (no autoconf):	2772	configuration (no autoconf):
2676		2773
2677	#define EV_STANDALONE 1	2774	#define EV_STANDALONE 1
2678	#include "ev.c"	2775	#include "ev.c"
2679		2776
2680	This will automatically include F<ev.h>, too, and should be done in a	2777	This will automatically include F<ev.h>, too, and should be done in a
2681	single C source file only to provide the function implementations. To use	2778	single C source file only to provide the function implementations. To use
2682	it, do the same for F<ev.h> in all files wishing to use this API (best	2779	it, do the same for F<ev.h> in all files wishing to use this API (best
2683	done by writing a wrapper around F<ev.h> that you can include instead and	2780	done by writing a wrapper around F<ev.h> that you can include instead and
2684	where you can put other configuration options):	2781	where you can put other configuration options):
2685		2782
2686	#define EV_STANDALONE 1	2783	#define EV_STANDALONE 1
2687	#include "ev.h"	2784	#include "ev.h"
2688		2785
2689	Both header files and implementation files can be compiled with a C++	2786	Both header files and implementation files can be compiled with a C++
2690	compiler (at least, thats a stated goal, and breakage will be treated	2787	compiler (at least, thats a stated goal, and breakage will be treated
2691	as a bug).	2788	as a bug).
2692		2789
2693	You need the following files in your source tree, or in a directory	2790	You need the following files in your source tree, or in a directory
2694	in your include path (e.g. in libev/ when using -Ilibev):	2791	in your include path (e.g. in libev/ when using -Ilibev):
2695		2792
2696	ev.h	2793	ev.h
2697	ev.c	2794	ev.c
2698	ev_vars.h	2795	ev_vars.h
2699	ev_wrap.h	2796	ev_wrap.h
2700		2797
2701	ev_win32.c required on win32 platforms only	2798	ev_win32.c required on win32 platforms only
2702		2799
2703	ev_select.c only when select backend is enabled (which is enabled by default)	2800	ev_select.c only when select backend is enabled (which is enabled by default)
2704	ev_poll.c only when poll backend is enabled (disabled by default)	2801	ev_poll.c only when poll backend is enabled (disabled by default)
2705	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2802	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2706	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2803	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2707	ev_port.c only when the solaris port backend is enabled (disabled by default)	2804	ev_port.c only when the solaris port backend is enabled (disabled by default)
2708		2805
2709	F<ev.c> includes the backend files directly when enabled, so you only need	2806	F<ev.c> includes the backend files directly when enabled, so you only need
2710	to compile this single file.	2807	to compile this single file.
2711		2808
2712	=head3 LIBEVENT COMPATIBILITY API	2809	=head3 LIBEVENT COMPATIBILITY API
2713		2810
2714	To include the libevent compatibility API, also include:	2811	To include the libevent compatibility API, also include:
2715		2812
2716	#include "event.c"	2813	#include "event.c"
2717		2814
2718	in the file including F<ev.c>, and:	2815	in the file including F<ev.c>, and:
2719		2816
2720	#include "event.h"	2817	#include "event.h"
2721		2818
2722	in the files that want to use the libevent API. This also includes F<ev.h>.	2819	in the files that want to use the libevent API. This also includes F<ev.h>.
2723		2820
2724	You need the following additional files for this:	2821	You need the following additional files for this:
2725		2822
2726	event.h	2823	event.h
2727	event.c	2824	event.c
2728		2825
2729	=head3 AUTOCONF SUPPORT	2826	=head3 AUTOCONF SUPPORT
2730		2827
2731	Instead of using C<EV_STANDALONE=1> and providing your config in	2828	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2732	whatever way you want, you can also C<m4_include([libev.m4])> in your	2829	whatever way you want, you can also C<m4_include([libev.m4])> in your
2733	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2830	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2734	include F<config.h> and configure itself accordingly.	2831	include F<config.h> and configure itself accordingly.
2735		2832
2736	For this of course you need the m4 file:	2833	For this of course you need the m4 file:
2737		2834
2738	libev.m4	2835	libev.m4
2739		2836
2740	=head2 PREPROCESSOR SYMBOLS/MACROS	2837	=head2 PREPROCESSOR SYMBOLS/MACROS
2741		2838
2742	Libev can be configured via a variety of preprocessor symbols you have to	2839	Libev can be configured via a variety of preprocessor symbols you have to
2743	define before including any of its files. The default in the absense of	2840	define before including any of its files. The default in the absence of
2744	autoconf is noted for every option.	2841	autoconf is noted for every option.
2745		2842
2746	=over 4	2843	=over 4
2747		2844
2748	=item EV_STANDALONE	2845	=item EV_STANDALONE
…		…
2754	F<event.h> that are not directly supported by the libev core alone.	2851	F<event.h> that are not directly supported by the libev core alone.
2755		2852
2756	=item EV_USE_MONOTONIC	2853	=item EV_USE_MONOTONIC
2757		2854
2758	If defined to be C<1>, libev will try to detect the availability of the	2855	If defined to be C<1>, libev will try to detect the availability of the
2759	monotonic clock option at both compiletime and runtime. Otherwise no use	2856	monotonic clock option at both compile time and runtime. Otherwise no use
2760	of the monotonic clock option will be attempted. If you enable this, you	2857	of the monotonic clock option will be attempted. If you enable this, you
2761	usually have to link against librt or something similar. Enabling it when	2858	usually have to link against librt or something similar. Enabling it when
2762	the functionality isn't available is safe, though, although you have	2859	the functionality isn't available is safe, though, although you have
2763	to make sure you link against any libraries where the C<clock_gettime>	2860	to make sure you link against any libraries where the C<clock_gettime>
2764	function is hiding in (often F<-lrt>).	2861	function is hiding in (often F<-lrt>).
2765		2862
2766	=item EV_USE_REALTIME	2863	=item EV_USE_REALTIME
2767		2864
2768	If defined to be C<1>, libev will try to detect the availability of the	2865	If defined to be C<1>, libev will try to detect the availability of the
2769	realtime clock option at compiletime (and assume its availability at	2866	real-time clock option at compile time (and assume its availability at
2770	runtime if successful). Otherwise no use of the realtime clock option will	2867	runtime if successful). Otherwise no use of the real-time clock option will
2771	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2868	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2772	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2869	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2773	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2870	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2774		2871
2775	=item EV_USE_NANOSLEEP	2872	=item EV_USE_NANOSLEEP
…		…
2786	2.7 or newer, otherwise disabled.	2883	2.7 or newer, otherwise disabled.
2787		2884
2788	=item EV_USE_SELECT	2885	=item EV_USE_SELECT
2789		2886
2790	If undefined or defined to be C<1>, libev will compile in support for the	2887	If undefined or defined to be C<1>, libev will compile in support for the
2791	C<select>(2) backend. No attempt at autodetection will be done: if no	2888	C<select>(2) backend. No attempt at auto-detection will be done: if no
2792	other method takes over, select will be it. Otherwise the select backend	2889	other method takes over, select will be it. Otherwise the select backend
2793	will not be compiled in.	2890	will not be compiled in.
2794		2891
2795	=item EV_SELECT_USE_FD_SET	2892	=item EV_SELECT_USE_FD_SET
2796		2893
2797	If defined to C<1>, then the select backend will use the system C<fd_set>	2894	If defined to C<1>, then the select backend will use the system C<fd_set>
2798	structure. This is useful if libev doesn't compile due to a missing	2895	structure. This is useful if libev doesn't compile due to a missing
2799	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	2896	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
2800	exotic systems. This usually limits the range of file descriptors to some	2897	exotic systems. This usually limits the range of file descriptors to some
2801	low limit such as 1024 or might have other limitations (winsocket only	2898	low limit such as 1024 or might have other limitations (winsocket only
2802	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	2899	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2803	influence the size of the C<fd_set> used.	2900	influence the size of the C<fd_set> used.
2804		2901
…		…
2853	otherwise another method will be used as fallback. This is the preferred	2950	otherwise another method will be used as fallback. This is the preferred
2854	backend for Solaris 10 systems.	2951	backend for Solaris 10 systems.
2855		2952
2856	=item EV_USE_DEVPOLL	2953	=item EV_USE_DEVPOLL
2857		2954
2858	reserved for future expansion, works like the USE symbols above.	2955	Reserved for future expansion, works like the USE symbols above.
2859		2956
2860	=item EV_USE_INOTIFY	2957	=item EV_USE_INOTIFY
2861		2958
2862	If defined to be C<1>, libev will compile in support for the Linux inotify	2959	If defined to be C<1>, libev will compile in support for the Linux inotify
2863	interface to speed up C<ev_stat> watchers. Its actual availability will	2960	interface to speed up C<ev_stat> watchers. Its actual availability will
…		…
2870	access is atomic with respect to other threads or signal contexts. No such	2967	access is atomic with respect to other threads or signal contexts. No such
2871	type is easily found in the C language, so you can provide your own type	2968	type is easily found in the C language, so you can provide your own type
2872	that you know is safe for your purposes. It is used both for signal handler "locking"	2969	that you know is safe for your purposes. It is used both for signal handler "locking"
2873	as well as for signal and thread safety in C<ev_async> watchers.	2970	as well as for signal and thread safety in C<ev_async> watchers.
2874		2971
2875	In the absense of this define, libev will use C<sig_atomic_t volatile>	2972	In the absence of this define, libev will use C<sig_atomic_t volatile>
2876	(from F<signal.h>), which is usually good enough on most platforms.	2973	(from F<signal.h>), which is usually good enough on most platforms.
2877		2974
2878	=item EV_H	2975	=item EV_H
2879		2976
2880	The name of the F<ev.h> header file used to include it. The default if	2977	The name of the F<ev.h> header file used to include it. The default if
…		…
2919	When doing priority-based operations, libev usually has to linearly search	3016	When doing priority-based operations, libev usually has to linearly search
2920	all the priorities, so having many of them (hundreds) uses a lot of space	3017	all the priorities, so having many of them (hundreds) uses a lot of space
2921	and time, so using the defaults of five priorities (-2 .. +2) is usually	3018	and time, so using the defaults of five priorities (-2 .. +2) is usually
2922	fine.	3019	fine.
2923		3020
2924	If your embedding app does not need any priorities, defining these both to	3021	If your embedding application does not need any priorities, defining these both to
2925	C<0> will save some memory and cpu.	3022	C<0> will save some memory and CPU.
2926		3023
2927	=item EV_PERIODIC_ENABLE	3024	=item EV_PERIODIC_ENABLE
2928		3025
2929	If undefined or defined to be C<1>, then periodic timers are supported. If	3026	If undefined or defined to be C<1>, then periodic timers are supported. If
2930	defined to be C<0>, then they are not. Disabling them saves a few kB of	3027	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
2957	defined to be C<0>, then they are not.	3054	defined to be C<0>, then they are not.
2958		3055
2959	=item EV_MINIMAL	3056	=item EV_MINIMAL
2960		3057
2961	If you need to shave off some kilobytes of code at the expense of some	3058	If you need to shave off some kilobytes of code at the expense of some
2962	speed, define this symbol to C<1>. Currently only used for gcc to override	3059	speed, define this symbol to C<1>. Currently this is used to override some
2963	some inlining decisions, saves roughly 30% codesize of amd64.	3060	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3061	much smaller 2-heap for timer management over the default 4-heap.
2964		3062
2965	=item EV_PID_HASHSIZE	3063	=item EV_PID_HASHSIZE
2966		3064
2967	C<ev_child> watchers use a small hash table to distribute workload by	3065	C<ev_child> watchers use a small hash table to distribute workload by
2968	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3066	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
…		…
2975	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	3073	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2976	usually more than enough. If you need to manage thousands of C<ev_stat>	3074	usually more than enough. If you need to manage thousands of C<ev_stat>
2977	watchers you might want to increase this value (I<must> be a power of	3075	watchers you might want to increase this value (I<must> be a power of
2978	two).	3076	two).
2979		3077
		3078	=item EV_USE_4HEAP
		3079
		3080	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3081	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3082	to C<1>. The 4-heap uses more complicated (longer) code but has
		3083	noticeably faster performance with many (thousands) of watchers.
		3084
		3085	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3086	(disabled).
		3087
		3088	=item EV_HEAP_CACHE_AT
		3089
		3090	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3091	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3092	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3093	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3094	but avoids random read accesses on heap changes. This improves performance
		3095	noticeably with with many (hundreds) of watchers.
		3096
		3097	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3098	(disabled).
		3099
		3100	=item EV_VERIFY
		3101
		3102	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3103	be done: If set to C<0>, no internal verification code will be compiled
		3104	in. If set to C<1>, then verification code will be compiled in, but not
		3105	called. If set to C<2>, then the internal verification code will be
		3106	called once per loop, which can slow down libev. If set to C<3>, then the
		3107	verification code will be called very frequently, which will slow down
		3108	libev considerably.
		3109
		3110	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3111	C<0.>
		3112
2980	=item EV_COMMON	3113	=item EV_COMMON
2981		3114
2982	By default, all watchers have a C<void *data> member. By redefining	3115	By default, all watchers have a C<void *data> member. By redefining
2983	this macro to a something else you can include more and other types of	3116	this macro to a something else you can include more and other types of
2984	members. You have to define it each time you include one of the files,	3117	members. You have to define it each time you include one of the files,
2985	though, and it must be identical each time.	3118	though, and it must be identical each time.
2986		3119
2987	For example, the perl EV module uses something like this:	3120	For example, the perl EV module uses something like this:
2988		3121
2989	#define EV_COMMON \	3122	#define EV_COMMON \
2990	SV *self; /* contains this struct */ \	3123	SV *self; /* contains this struct */ \
2991	SV *cb_sv, *fh /* note no trailing ";" */	3124	SV *cb_sv, *fh /* note no trailing ";" */
2992		3125
2993	=item EV_CB_DECLARE (type)	3126	=item EV_CB_DECLARE (type)
2994		3127
2995	=item EV_CB_INVOKE (watcher, revents)	3128	=item EV_CB_INVOKE (watcher, revents)
2996		3129
…		…
3003	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3136	avoid the C<struct ev_loop *> as first argument in all cases, or to use
3004	method calls instead of plain function calls in C++.	3137	method calls instead of plain function calls in C++.
3005		3138
3006	=head2 EXPORTED API SYMBOLS	3139	=head2 EXPORTED API SYMBOLS
3007		3140
3008	If you need to re-export the API (e.g. via a dll) and you need a list of	3141	If you need to re-export the API (e.g. via a DLL) and you need a list of
3009	exported symbols, you can use the provided F<Symbol.*> files which list	3142	exported symbols, you can use the provided F<Symbol.*> files which list
3010	all public symbols, one per line:	3143	all public symbols, one per line:
3011		3144
3012	Symbols.ev for libev proper	3145	Symbols.ev for libev proper
3013	Symbols.event for the libevent emulation	3146	Symbols.event for the libevent emulation
3014		3147
3015	This can also be used to rename all public symbols to avoid clashes with	3148	This can also be used to rename all public symbols to avoid clashes with
3016	multiple versions of libev linked together (which is obviously bad in	3149	multiple versions of libev linked together (which is obviously bad in
3017	itself, but sometimes it is inconvinient to avoid this).	3150	itself, but sometimes it is inconvenient to avoid this).
3018		3151
3019	A sed command like this will create wrapper C<#define>'s that you need to	3152	A sed command like this will create wrapper C<#define>'s that you need to
3020	include before including F<ev.h>:	3153	include before including F<ev.h>:
3021		3154
3022	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3155	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3039	file.	3172	file.
3040		3173
3041	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3174	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3042	that everybody includes and which overrides some configure choices:	3175	that everybody includes and which overrides some configure choices:
3043		3176
3044	#define EV_MINIMAL 1	3177	#define EV_MINIMAL 1
3045	#define EV_USE_POLL 0	3178	#define EV_USE_POLL 0
3046	#define EV_MULTIPLICITY 0	3179	#define EV_MULTIPLICITY 0
3047	#define EV_PERIODIC_ENABLE 0	3180	#define EV_PERIODIC_ENABLE 0
3048	#define EV_STAT_ENABLE 0	3181	#define EV_STAT_ENABLE 0
3049	#define EV_FORK_ENABLE 0	3182	#define EV_FORK_ENABLE 0
3050	#define EV_CONFIG_H <config.h>	3183	#define EV_CONFIG_H <config.h>
3051	#define EV_MINPRI 0	3184	#define EV_MINPRI 0
3052	#define EV_MAXPRI 0	3185	#define EV_MAXPRI 0
3053		3186
3054	#include "ev++.h"	3187	#include "ev++.h"
3055		3188
3056	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3189	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3057		3190
3058	#include "ev_cpp.h"	3191	#include "ev_cpp.h"
3059	#include "ev.c"	3192	#include "ev.c"
		3193
		3194
		3195	=head1 THREADS AND COROUTINES
		3196
		3197	=head2 THREADS
		3198
		3199	Libev itself is completely thread-safe, but it uses no locking. This
		3200	means that you can use as many loops as you want in parallel, as long as
		3201	only one thread ever calls into one libev function with the same loop
		3202	parameter.
		3203
		3204	Or put differently: calls with different loop parameters can be done in
		3205	parallel from multiple threads, calls with the same loop parameter must be
		3206	done serially (but can be done from different threads, as long as only one
		3207	thread ever is inside a call at any point in time, e.g. by using a mutex
		3208	per loop).
		3209
		3210	If you want to know which design (one loop, locking, or multiple loops
		3211	without or something else still) is best for your problem, then I cannot
		3212	help you. I can give some generic advice however:
		3213
		3214	=over 4
		3215
		3216	=item * most applications have a main thread: use the default libev loop
		3217	in that thread, or create a separate thread running only the default loop.
		3218
		3219	This helps integrating other libraries or software modules that use libev
		3220	themselves and don't care/know about threading.
		3221
		3222	=item * one loop per thread is usually a good model.
		3223
		3224	Doing this is almost never wrong, sometimes a better-performance model
		3225	exists, but it is always a good start.
		3226
		3227	=item * other models exist, such as the leader/follower pattern, where one
		3228	loop is handed through multiple threads in a kind of round-robin fashion.
		3229
		3230	Choosing a model is hard - look around, learn, know that usually you can do
		3231	better than you currently do :-)
		3232
		3233	=item * often you need to talk to some other thread which blocks in the
		3234	event loop - C<ev_async> watchers can be used to wake them up from other
		3235	threads safely (or from signal contexts...).
		3236
		3237	=back
		3238
		3239	=head2 COROUTINES
		3240
		3241	Libev is much more accommodating to coroutines ("cooperative threads"):
		3242	libev fully supports nesting calls to it's functions from different
		3243	coroutines (e.g. you can call C<ev_loop> on the same loop from two
		3244	different coroutines and switch freely between both coroutines running the
		3245	loop, as long as you don't confuse yourself). The only exception is that
		3246	you must not do this from C<ev_periodic> reschedule callbacks.
		3247
		3248	Care has been invested into making sure that libev does not keep local
		3249	state inside C<ev_loop>, and other calls do not usually allow coroutine
		3250	switches.
3060		3251
3061		3252
3062	=head1 COMPLEXITIES	3253	=head1 COMPLEXITIES
3063		3254
3064	In this section the complexities of (many of) the algorithms used inside	3255	In this section the complexities of (many of) the algorithms used inside
…		…
3096	correct watcher to remove. The lists are usually short (you don't usually	3287	correct watcher to remove. The lists are usually short (you don't usually
3097	have many watchers waiting for the same fd or signal).	3288	have many watchers waiting for the same fd or signal).
3098		3289
3099	=item Finding the next timer in each loop iteration: O(1)	3290	=item Finding the next timer in each loop iteration: O(1)
3100		3291
3101	By virtue of using a binary heap, the next timer is always found at the	3292	By virtue of using a binary or 4-heap, the next timer is always found at a
3102	beginning of the storage array.	3293	fixed position in the storage array.
3103		3294
3104	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3295	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3105		3296
3106	A change means an I/O watcher gets started or stopped, which requires	3297	A change means an I/O watcher gets started or stopped, which requires
3107	libev to recalculate its status (and possibly tell the kernel, depending	3298	libev to recalculate its status (and possibly tell the kernel, depending
3108	on backend and wether C<ev_io_set> was used).	3299	on backend and whether C<ev_io_set> was used).
3109		3300
3110	=item Activating one watcher (putting it into the pending state): O(1)	3301	=item Activating one watcher (putting it into the pending state): O(1)
3111		3302
3112	=item Priority handling: O(number_of_priorities)	3303	=item Priority handling: O(number_of_priorities)
3113		3304
…		…
3120		3311
3121	=item Processing ev_async_send: O(number_of_async_watchers)	3312	=item Processing ev_async_send: O(number_of_async_watchers)
3122		3313
3123	=item Processing signals: O(max_signal_number)	3314	=item Processing signals: O(max_signal_number)
3124		3315
3125	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3316	Sending involves a system call I<iff> there were no other C<ev_async_send>
3126	calls in the current loop iteration. Checking for async and signal events	3317	calls in the current loop iteration. Checking for async and signal events
3127	involves iterating over all running async watchers or all signal numbers.	3318	involves iterating over all running async watchers or all signal numbers.
3128		3319
3129	=back	3320	=back
3130		3321
3131		3322
3132	=head1 Win32 platform limitations and workarounds	3323	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3133		3324
3134	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3325	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3135	requires, and its I/O model is fundamentally incompatible with the POSIX	3326	requires, and its I/O model is fundamentally incompatible with the POSIX
3136	model. Libev still offers limited functionality on this platform in	3327	model. Libev still offers limited functionality on this platform in
3137	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3328	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3138	descriptors. This only applies when using Win32 natively, not when using	3329	descriptors. This only applies when using Win32 natively, not when using
3139	e.g. cygwin.	3330	e.g. cygwin.
3140		3331
		3332	Lifting these limitations would basically require the full
		3333	re-implementation of the I/O system. If you are into these kinds of
		3334	things, then note that glib does exactly that for you in a very portable
		3335	way (note also that glib is the slowest event library known to man).
		3336
3141	There is no supported compilation method available on windows except	3337	There is no supported compilation method available on windows except
3142	embedding it into other applications.	3338	embedding it into other applications.
3143		3339
		3340	Not a libev limitation but worth mentioning: windows apparently doesn't
		3341	accept large writes: instead of resulting in a partial write, windows will
		3342	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3343	so make sure you only write small amounts into your sockets (less than a
		3344	megabyte seems safe, but thsi apparently depends on the amount of memory
		3345	available).
		3346
3144	Due to the many, low, and arbitrary limits on the win32 platform and the	3347	Due to the many, low, and arbitrary limits on the win32 platform and
3145	abysmal performance of winsockets, using a large number of sockets is not	3348	the abysmal performance of winsockets, using a large number of sockets
3146	recommended (and not reasonable). If your program needs to use more than	3349	is not recommended (and not reasonable). If your program needs to use
3147	a hundred or so sockets, then likely it needs to use a totally different	3350	more than a hundred or so sockets, then likely it needs to use a totally
3148	implementation for windows, as libev offers the POSIX model, which cannot	3351	different implementation for windows, as libev offers the POSIX readiness
3149	be implemented efficiently on windows (microsoft monopoly games).	3352	notification model, which cannot be implemented efficiently on windows
		3353	(Microsoft monopoly games).
		3354
		3355	A typical way to use libev under windows is to embed it (see the embedding
		3356	section for details) and use the following F<evwrap.h> header file instead
		3357	of F<ev.h>:
		3358
		3359	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3360	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3361
		3362	#include "ev.h"
		3363
		3364	And compile the following F<evwrap.c> file into your project (make sure
		3365	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3366
		3367	#include "evwrap.h"
		3368	#include "ev.c"
3150		3369
3151	=over 4	3370	=over 4
3152		3371
3153	=item The winsocket select function	3372	=item The winsocket select function
3154		3373
3155	The winsocket C<select> function doesn't follow POSIX in that it requires	3374	The winsocket C<select> function doesn't follow POSIX in that it
3156	socket I<handles> and not socket I<file descriptors>. This makes select	3375	requires socket I<handles> and not socket I<file descriptors> (it is
3157	very inefficient, and also requires a mapping from file descriptors	3376	also extremely buggy). This makes select very inefficient, and also
3158	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,	3377	requires a mapping from file descriptors to socket handles (the Microsoft
3159	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor	3378	C runtime provides the function C<_open_osfhandle> for this). See the
3160	symbols for more info.	3379	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3380	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3161		3381
3162	The configuration for a "naked" win32 using the microsoft runtime	3382	The configuration for a "naked" win32 using the Microsoft runtime
3163	libraries and raw winsocket select is:	3383	libraries and raw winsocket select is:
3164		3384
3165	#define EV_USE_SELECT 1	3385	#define EV_USE_SELECT 1
3166	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3386	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3167		3387
3168	Note that winsockets handling of fd sets is O(n), so you can easily get a	3388	Note that winsockets handling of fd sets is O(n), so you can easily get a
3169	complexity in the O(n²) range when using win32.	3389	complexity in the O(n²) range when using win32.
3170		3390
3171	=item Limited number of file descriptors	3391	=item Limited number of file descriptors
3172		3392
3173	Windows has numerous arbitrary (and low) limits on things. Early versions	3393	Windows has numerous arbitrary (and low) limits on things.
3174	of winsocket's select only supported waiting for a max. of C<64> handles	3394
		3395	Early versions of winsocket's select only supported waiting for a maximum
3175	(probably owning to the fact that all windows kernels can only wait for	3396	of C<64> handles (probably owning to the fact that all windows kernels
3176	C<64> things at the same time internally; microsoft recommends spawning a	3397	can only wait for C<64> things at the same time internally; Microsoft
3177	chain of threads and wait for 63 handles and the previous thread in each).	3398	recommends spawning a chain of threads and wait for 63 handles and the
		3399	previous thread in each. Great).
3178		3400
3179	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3401	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3180	to some high number (e.g. C<2048>) before compiling the winsocket select	3402	to some high number (e.g. C<2048>) before compiling the winsocket select
3181	call (which might be in libev or elsewhere, for example, perl does its own	3403	call (which might be in libev or elsewhere, for example, perl does its own
3182	select emulation on windows).	3404	select emulation on windows).
3183		3405
3184	Another limit is the number of file descriptors in the microsoft runtime	3406	Another limit is the number of file descriptors in the Microsoft runtime
3185	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3407	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3186	or something like this inside microsoft). You can increase this by calling	3408	or something like this inside Microsoft). You can increase this by calling
3187	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3409	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3188	arbitrary limit), but is broken in many versions of the microsoft runtime	3410	arbitrary limit), but is broken in many versions of the Microsoft runtime
3189	libraries.	3411	libraries.
3190		3412
3191	This might get you to about C<512> or C<2048> sockets (depending on	3413	This might get you to about C<512> or C<2048> sockets (depending on
3192	windows version and/or the phase of the moon). To get more, you need to	3414	windows version and/or the phase of the moon). To get more, you need to
3193	wrap all I/O functions and provide your own fd management, but the cost of	3415	wrap all I/O functions and provide your own fd management, but the cost of
3194	calling select (O(n²)) will likely make this unworkable.	3416	calling select (O(n²)) will likely make this unworkable.
3195		3417
3196	=back	3418	=back
3197		3419
3198		3420
		3421	=head1 PORTABILITY REQUIREMENTS
		3422
		3423	In addition to a working ISO-C implementation, libev relies on a few
		3424	additional extensions:
		3425
		3426	=over 4
		3427
		3428	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3429	calling conventions regardless of C<ev_watcher_type *>.
		3430
		3431	Libev assumes not only that all watcher pointers have the same internal
		3432	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3433	assumes that the same (machine) code can be used to call any watcher
		3434	callback: The watcher callbacks have different type signatures, but libev
		3435	calls them using an C<ev_watcher *> internally.
		3436
		3437	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3438
		3439	The type C<sig_atomic_t volatile> (or whatever is defined as
		3440	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3441	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3442	believed to be sufficiently portable.
		3443
		3444	=item C<sigprocmask> must work in a threaded environment
		3445
		3446	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3447	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3448	pthread implementations will either allow C<sigprocmask> in the "main
		3449	thread" or will block signals process-wide, both behaviours would
		3450	be compatible with libev. Interaction between C<sigprocmask> and
		3451	C<pthread_sigmask> could complicate things, however.
		3452
		3453	The most portable way to handle signals is to block signals in all threads
		3454	except the initial one, and run the default loop in the initial thread as
		3455	well.
		3456
		3457	=item C<long> must be large enough for common memory allocation sizes
		3458
		3459	To improve portability and simplify using libev, libev uses C<long>
		3460	internally instead of C<size_t> when allocating its data structures. On
		3461	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3462	is still at least 31 bits everywhere, which is enough for hundreds of
		3463	millions of watchers.
		3464
		3465	=item C<double> must hold a time value in seconds with enough accuracy
		3466
		3467	The type C<double> is used to represent timestamps. It is required to
		3468	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3469	enough for at least into the year 4000. This requirement is fulfilled by
		3470	implementations implementing IEEE 754 (basically all existing ones).
		3471
		3472	=back
		3473
		3474	If you know of other additional requirements drop me a note.
		3475
		3476
		3477	=head1 COMPILER WARNINGS
		3478
		3479	Depending on your compiler and compiler settings, you might get no or a
		3480	lot of warnings when compiling libev code. Some people are apparently
		3481	scared by this.
		3482
		3483	However, these are unavoidable for many reasons. For one, each compiler
		3484	has different warnings, and each user has different tastes regarding
		3485	warning options. "Warn-free" code therefore cannot be a goal except when
		3486	targeting a specific compiler and compiler-version.
		3487
		3488	Another reason is that some compiler warnings require elaborate
		3489	workarounds, or other changes to the code that make it less clear and less
		3490	maintainable.
		3491
		3492	And of course, some compiler warnings are just plain stupid, or simply
		3493	wrong (because they don't actually warn about the condition their message
		3494	seems to warn about).
		3495
		3496	While libev is written to generate as few warnings as possible,
		3497	"warn-free" code is not a goal, and it is recommended not to build libev
		3498	with any compiler warnings enabled unless you are prepared to cope with
		3499	them (e.g. by ignoring them). Remember that warnings are just that:
		3500	warnings, not errors, or proof of bugs.
		3501
		3502
		3503	=head1 VALGRIND
		3504
		3505	Valgrind has a special section here because it is a popular tool that is
		3506	highly useful, but valgrind reports are very hard to interpret.
		3507
		3508	If you think you found a bug (memory leak, uninitialised data access etc.)
		3509	in libev, then check twice: If valgrind reports something like:
		3510
		3511	==2274== definitely lost: 0 bytes in 0 blocks.
		3512	==2274== possibly lost: 0 bytes in 0 blocks.
		3513	==2274== still reachable: 256 bytes in 1 blocks.
		3514
		3515	Then there is no memory leak. Similarly, under some circumstances,
		3516	valgrind might report kernel bugs as if it were a bug in libev, or it
		3517	might be confused (it is a very good tool, but only a tool).
		3518
		3519	If you are unsure about something, feel free to contact the mailing list
		3520	with the full valgrind report and an explanation on why you think this is
		3521	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3522	no bug" answer and take the chance of learning how to interpret valgrind
		3523	properly.
		3524
		3525	If you need, for some reason, empty reports from valgrind for your project
		3526	I suggest using suppression lists.
		3527
		3528
3199	=head1 AUTHOR	3529	=head1 AUTHOR
3200		3530
3201	Marc Lehmann <libev@schmorp.de>.	3531	Marc Lehmann <libev@schmorp.de>.
3202		3532

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