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Revision 1.136 by root, Thu Mar 13 13:06:16 2008 UTC vs.
Revision 1.169 by root, Fri Jun 20 23:31:19 2008 UTC

…		…
2		2
3	libev - a high performance full-featured event loop written in C	3	libev - a high performance full-featured event loop written in C
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
9	=head2 EXAMPLE PROGRAM	9	=head2 EXAMPLE PROGRAM
10		10
11	// a single header file is required	11	// a single header file is required
12	#include <ev.h>	12	#include <ev.h>
13		13
14	// every watcher type has its own typedef'd struct	14	// every watcher type has its own typedef'd struct
15	// with the name ev_<type>	15	// with the name ev_<type>
16	ev_io stdin_watcher;	16	ev_io stdin_watcher;
17	ev_timer timeout_watcher;	17	ev_timer timeout_watcher;
18		18
19	// all watcher callbacks have a similar signature	19	// all watcher callbacks have a similar signature
20	// this callback is called when data is readable on stdin	20	// this callback is called when data is readable on stdin
21	static void	21	static void
22	stdin_cb (EV_P_ struct ev_io *w, int revents)	22	stdin_cb (EV_P_ struct ev_io *w, int revents)
23	{	23	{
24	puts ("stdin ready");	24	puts ("stdin ready");
25	// for one-shot events, one must manually stop the watcher	25	// for one-shot events, one must manually stop the watcher
26	// with its corresponding stop function.	26	// with its corresponding stop function.
27	ev_io_stop (EV_A_ w);	27	ev_io_stop (EV_A_ w);
28		28
29	// this causes all nested ev_loop's to stop iterating	29	// this causes all nested ev_loop's to stop iterating
30	ev_unloop (EV_A_ EVUNLOOP_ALL);	30	ev_unloop (EV_A_ EVUNLOOP_ALL);
31	}	31	}
32		32
33	// another callback, this time for a time-out	33	// another callback, this time for a time-out
34	static void	34	static void
35	timeout_cb (EV_P_ struct ev_timer *w, int revents)	35	timeout_cb (EV_P_ struct ev_timer *w, int revents)
36	{	36	{
37	puts ("timeout");	37	puts ("timeout");
38	// this causes the innermost ev_loop to stop iterating	38	// this causes the innermost ev_loop to stop iterating
39	ev_unloop (EV_A_ EVUNLOOP_ONE);	39	ev_unloop (EV_A_ EVUNLOOP_ONE);
40	}	40	}
41		41
42	int	42	int
43	main (void)	43	main (void)
44	{	44	{
45	// use the default event loop unless you have special needs	45	// use the default event loop unless you have special needs
46	struct ev_loop *loop = ev_default_loop (0);	46	struct ev_loop *loop = ev_default_loop (0);
47		47
48	// initialise an io watcher, then start it	48	// initialise an io watcher, then start it
49	// this one will watch for stdin to become readable	49	// this one will watch for stdin to become readable
50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
51	ev_io_start (loop, &stdin_watcher);	51	ev_io_start (loop, &stdin_watcher);
52		52
53	// initialise a timer watcher, then start it	53	// initialise a timer watcher, then start it
54	// simple non-repeating 5.5 second timeout	54	// simple non-repeating 5.5 second timeout
55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
56	ev_timer_start (loop, &timeout_watcher);	56	ev_timer_start (loop, &timeout_watcher);
57		57
58	// now wait for events to arrive	58	// now wait for events to arrive
59	ev_loop (loop, 0);	59	ev_loop (loop, 0);
60		60
61	// unloop was called, so exit	61	// unloop was called, so exit
62	return 0;	62	return 0;
63	}	63	}
64		64
65	=head1 DESCRIPTION	65	=head1 DESCRIPTION
66		66
67	The newest version of this document is also available as an html-formatted	67	The newest version of this document is also available as an html-formatted
68	web page you might find easier to navigate when reading it for the first	68	web page you might find easier to navigate when reading it for the first
69	time: L<http://cvs.schmorp.de/libev/ev.html>.	69	time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>.
70		70
71	Libev is an event loop: you register interest in certain events (such as a	71	Libev is an event loop: you register interest in certain events (such as a
72	file descriptor being readable or a timeout occurring), and it will manage	72	file descriptor being readable or a timeout occurring), and it will manage
73	these event sources and provide your program with events.	73	these event sources and provide your program with events.
74		74
…		…
113	Libev represents time as a single floating point number, representing the	113	Libev represents time as a single floating point number, representing the
114	(fractional) number of seconds since the (POSIX) epoch (somewhere near	114	(fractional) number of seconds since the (POSIX) epoch (somewhere near
115	the beginning of 1970, details are complicated, don't ask). This type is	115	the beginning of 1970, details are complicated, don't ask). This type is
116	called C<ev_tstamp>, which is what you should use too. It usually aliases	116	called C<ev_tstamp>, which is what you should use too. It usually aliases
117	to the C<double> type in C, and when you need to do any calculations on	117	to the C<double> type in C, and when you need to do any calculations on
118	it, you should treat it as some floatingpoint value. Unlike the name	118	it, you should treat it as some floating point value. Unlike the name
119	component C<stamp> might indicate, it is also used for time differences	119	component C<stamp> might indicate, it is also used for time differences
120	throughout libev.	120	throughout libev.
		121
		122	=head1 ERROR HANDLING
		123
		124	Libev knows three classes of errors: operating system errors, usage errors
		125	and internal errors (bugs).
		126
		127	When libev catches an operating system error it cannot handle (for example
		128	a system call indicating a condition libev cannot fix), it calls the callback
		129	set via C<ev_set_syserr_cb>, which is supposed to fix the problem or
		130	abort. The default is to print a diagnostic message and to call C<abort
		131	()>.
		132
		133	When libev detects a usage error such as a negative timer interval, then
		134	it will print a diagnostic message and abort (via the C<assert> mechanism,
		135	so C<NDEBUG> will disable this checking): these are programming errors in
		136	the libev caller and need to be fixed there.
		137
		138	Libev also has a few internal error-checking C<assert>ions, and also has
		139	extensive consistency checking code. These do not trigger under normal
		140	circumstances, as they indicate either a bug in libev or worse.
		141
121		142
122	=head1 GLOBAL FUNCTIONS	143	=head1 GLOBAL FUNCTIONS
123		144
124	These functions can be called anytime, even before initialising the	145	These functions can be called anytime, even before initialising the
125	library in any way.	146	library in any way.
…		…
134		155
135	=item ev_sleep (ev_tstamp interval)	156	=item ev_sleep (ev_tstamp interval)
136		157
137	Sleep for the given interval: The current thread will be blocked until	158	Sleep for the given interval: The current thread will be blocked until
138	either it is interrupted or the given time interval has passed. Basically	159	either it is interrupted or the given time interval has passed. Basically
139	this is a subsecond-resolution C<sleep ()>.	160	this is a sub-second-resolution C<sleep ()>.
140		161
141	=item int ev_version_major ()	162	=item int ev_version_major ()
142		163
143	=item int ev_version_minor ()	164	=item int ev_version_minor ()
144		165
…		…
157	not a problem.	178	not a problem.
158		179
159	Example: Make sure we haven't accidentally been linked against the wrong	180	Example: Make sure we haven't accidentally been linked against the wrong
160	version.	181	version.
161		182
162	assert (("libev version mismatch",	183	assert (("libev version mismatch",
163	ev_version_major () == EV_VERSION_MAJOR	184	ev_version_major () == EV_VERSION_MAJOR
164	&& ev_version_minor () >= EV_VERSION_MINOR));	185	&& ev_version_minor () >= EV_VERSION_MINOR));
165		186
166	=item unsigned int ev_supported_backends ()	187	=item unsigned int ev_supported_backends ()
167		188
168	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>	189	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>
169	value) compiled into this binary of libev (independent of their	190	value) compiled into this binary of libev (independent of their
…		…
171	a description of the set values.	192	a description of the set values.
172		193
173	Example: make sure we have the epoll method, because yeah this is cool and	194	Example: make sure we have the epoll method, because yeah this is cool and
174	a must have and can we have a torrent of it please!!!11	195	a must have and can we have a torrent of it please!!!11
175		196
176	assert (("sorry, no epoll, no sex",	197	assert (("sorry, no epoll, no sex",
177	ev_supported_backends () & EVBACKEND_EPOLL));	198	ev_supported_backends () & EVBACKEND_EPOLL));
178		199
179	=item unsigned int ev_recommended_backends ()	200	=item unsigned int ev_recommended_backends ()
180		201
181	Return the set of all backends compiled into this binary of libev and also	202	Return the set of all backends compiled into this binary of libev and also
182	recommended for this platform. This set is often smaller than the one	203	recommended for this platform. This set is often smaller than the one
183	returned by C<ev_supported_backends>, as for example kqueue is broken on	204	returned by C<ev_supported_backends>, as for example kqueue is broken on
184	most BSDs and will not be autodetected unless you explicitly request it	205	most BSDs and will not be auto-detected unless you explicitly request it
185	(assuming you know what you are doing). This is the set of backends that	206	(assuming you know what you are doing). This is the set of backends that
186	libev will probe for if you specify no backends explicitly.	207	libev will probe for if you specify no backends explicitly.
187		208
188	=item unsigned int ev_embeddable_backends ()	209	=item unsigned int ev_embeddable_backends ()
189		210
…		…
196	See the description of C<ev_embed> watchers for more info.	217	See the description of C<ev_embed> watchers for more info.
197		218
198	=item ev_set_allocator (void *(*cb)(void *ptr, long size))	219	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
199		220
200	Sets the allocation function to use (the prototype is similar - the	221	Sets the allocation function to use (the prototype is similar - the
201	semantics is identical - to the realloc C function). It is used to	222	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
202	allocate and free memory (no surprises here). If it returns zero when	223	used to allocate and free memory (no surprises here). If it returns zero
203	memory needs to be allocated, the library might abort or take some	224	when memory needs to be allocated (C<size != 0>), the library might abort
204	potentially destructive action. The default is your system realloc	225	or take some potentially destructive action.
205	function.	226
		227	Since some systems (at least OpenBSD and Darwin) fail to implement
		228	correct C<realloc> semantics, libev will use a wrapper around the system
		229	C<realloc> and C<free> functions by default.
206		230
207	You could override this function in high-availability programs to, say,	231	You could override this function in high-availability programs to, say,
208	free some memory if it cannot allocate memory, to use a special allocator,	232	free some memory if it cannot allocate memory, to use a special allocator,
209	or even to sleep a while and retry until some memory is available.	233	or even to sleep a while and retry until some memory is available.
210		234
211	Example: Replace the libev allocator with one that waits a bit and then	235	Example: Replace the libev allocator with one that waits a bit and then
212	retries).	236	retries (example requires a standards-compliant C<realloc>).
213		237
214	static void *	238	static void *
215	persistent_realloc (void *ptr, size_t size)	239	persistent_realloc (void *ptr, size_t size)
216	{	240	{
217	for (;;)	241	for (;;)
…		…
228	...	252	...
229	ev_set_allocator (persistent_realloc);	253	ev_set_allocator (persistent_realloc);
230		254
231	=item ev_set_syserr_cb (void (*cb)(const char *msg));	255	=item ev_set_syserr_cb (void (*cb)(const char *msg));
232		256
233	Set the callback function to call on a retryable syscall error (such	257	Set the callback function to call on a retryable system call error (such
234	as failed select, poll, epoll_wait). The message is a printable string	258	as failed select, poll, epoll_wait). The message is a printable string
235	indicating the system call or subsystem causing the problem. If this	259	indicating the system call or subsystem causing the problem. If this
236	callback is set, then libev will expect it to remedy the sitution, no	260	callback is set, then libev will expect it to remedy the situation, no
237	matter what, when it returns. That is, libev will generally retry the	261	matter what, when it returns. That is, libev will generally retry the
238	requested operation, or, if the condition doesn't go away, do bad stuff	262	requested operation, or, if the condition doesn't go away, do bad stuff
239	(such as abort).	263	(such as abort).
240		264
241	Example: This is basically the same thing that libev does internally, too.	265	Example: This is basically the same thing that libev does internally, too.
…		…
255	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	279	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP
256		280
257	An event loop is described by a C<struct ev_loop *>. The library knows two	281	An event loop is described by a C<struct ev_loop *>. The library knows two
258	types of such loops, the I<default> loop, which supports signals and child	282	types of such loops, the I<default> loop, which supports signals and child
259	events, and dynamically created loops which do not.	283	events, and dynamically created loops which do not.
260
261	If you use threads, a common model is to run the default event loop
262	in your main thread (or in a separate thread) and for each thread you
263	create, you also create another event loop. Libev itself does no locking
264	whatsoever, so if you mix calls to the same event loop in different
265	threads, make sure you lock (this is usually a bad idea, though, even if
266	done correctly, because it's hideous and inefficient).
267		284
268	=over 4	285	=over 4
269		286
270	=item struct ev_loop *ev_default_loop (unsigned int flags)	287	=item struct ev_loop *ev_default_loop (unsigned int flags)
271		288
…		…
275	flags. If that is troubling you, check C<ev_backend ()> afterwards).	292	flags. If that is troubling you, check C<ev_backend ()> afterwards).
276		293
277	If you don't know what event loop to use, use the one returned from this	294	If you don't know what event loop to use, use the one returned from this
278	function.	295	function.
279		296
		297	Note that this function is I<not> thread-safe, so if you want to use it
		298	from multiple threads, you have to lock (note also that this is unlikely,
		299	as loops cannot bes hared easily between threads anyway).
		300
280	The default loop is the only loop that can handle C<ev_signal> and	301	The default loop is the only loop that can handle C<ev_signal> and
281	C<ev_child> watchers, and to do this, it always registers a handler	302	C<ev_child> watchers, and to do this, it always registers a handler
282	for C<SIGCHLD>. If this is a problem for your app you can either	303	for C<SIGCHLD>. If this is a problem for your application you can either
283	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	304	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
284	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	305	can simply overwrite the C<SIGCHLD> signal handler I<after> calling
285	C<ev_default_init>.	306	C<ev_default_init>.
286		307
287	The flags argument can be used to specify special behaviour or specific	308	The flags argument can be used to specify special behaviour or specific
…		…
296	The default flags value. Use this if you have no clue (it's the right	317	The default flags value. Use this if you have no clue (it's the right
297	thing, believe me).	318	thing, believe me).
298		319
299	=item C<EVFLAG_NOENV>	320	=item C<EVFLAG_NOENV>
300		321
301	If this flag bit is ored into the flag value (or the program runs setuid	322	If this flag bit is or'ed into the flag value (or the program runs setuid
302	or setgid) then libev will I<not> look at the environment variable	323	or setgid) then libev will I<not> look at the environment variable
303	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	324	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
304	override the flags completely if it is found in the environment. This is	325	override the flags completely if it is found in the environment. This is
305	useful to try out specific backends to test their performance, or to work	326	useful to try out specific backends to test their performance, or to work
306	around bugs.	327	around bugs.
…		…
313		334
314	This works by calling C<getpid ()> on every iteration of the loop,	335	This works by calling C<getpid ()> on every iteration of the loop,
315	and thus this might slow down your event loop if you do a lot of loop	336	and thus this might slow down your event loop if you do a lot of loop
316	iterations and little real work, but is usually not noticeable (on my	337	iterations and little real work, but is usually not noticeable (on my
317	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	338	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
318	without a syscall and thus I<very> fast, but my GNU/Linux system also has	339	without a system call and thus I<very> fast, but my GNU/Linux system also has
319	C<pthread_atfork> which is even faster).	340	C<pthread_atfork> which is even faster).
320		341
321	The big advantage of this flag is that you can forget about fork (and	342	The big advantage of this flag is that you can forget about fork (and
322	forget about forgetting to tell libev about forking) when you use this	343	forget about forgetting to tell libev about forking) when you use this
323	flag.	344	flag.
324		345
325	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>	346	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
326	environment variable.	347	environment variable.
327		348
328	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	349	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
329		350
330	This is your standard select(2) backend. Not I<completely> standard, as	351	This is your standard select(2) backend. Not I<completely> standard, as
…		…
332	but if that fails, expect a fairly low limit on the number of fds when	353	but if that fails, expect a fairly low limit on the number of fds when
333	using this backend. It doesn't scale too well (O(highest_fd)), but its	354	using this backend. It doesn't scale too well (O(highest_fd)), but its
334	usually the fastest backend for a low number of (low-numbered :) fds.	355	usually the fastest backend for a low number of (low-numbered :) fds.
335		356
336	To get good performance out of this backend you need a high amount of	357	To get good performance out of this backend you need a high amount of
337	parallelity (most of the file descriptors should be busy). If you are	358	parallelism (most of the file descriptors should be busy). If you are
338	writing a server, you should C<accept ()> in a loop to accept as many	359	writing a server, you should C<accept ()> in a loop to accept as many
339	connections as possible during one iteration. You might also want to have	360	connections as possible during one iteration. You might also want to have
340	a look at C<ev_set_io_collect_interval ()> to increase the amount of	361	a look at C<ev_set_io_collect_interval ()> to increase the amount of
341	readyness notifications you get per iteration.	362	readiness notifications you get per iteration.
342		363
343	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	364	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
344		365
345	And this is your standard poll(2) backend. It's more complicated	366	And this is your standard poll(2) backend. It's more complicated
346	than select, but handles sparse fds better and has no artificial	367	than select, but handles sparse fds better and has no artificial
…		…
354	For few fds, this backend is a bit little slower than poll and select,	375	For few fds, this backend is a bit little slower than poll and select,
355	but it scales phenomenally better. While poll and select usually scale	376	but it scales phenomenally better. While poll and select usually scale
356	like O(total_fds) where n is the total number of fds (or the highest fd),	377	like O(total_fds) where n is the total number of fds (or the highest fd),
357	epoll scales either O(1) or O(active_fds). The epoll design has a number	378	epoll scales either O(1) or O(active_fds). The epoll design has a number
358	of shortcomings, such as silently dropping events in some hard-to-detect	379	of shortcomings, such as silently dropping events in some hard-to-detect
359	cases and rewiring a syscall per fd change, no fork support and bad	380	cases and requiring a system call per fd change, no fork support and bad
360	support for dup.	381	support for dup.
361		382
362	While stopping, setting and starting an I/O watcher in the same iteration	383	While stopping, setting and starting an I/O watcher in the same iteration
363	will result in some caching, there is still a syscall per such incident	384	will result in some caching, there is still a system call per such incident
364	(because the fd could point to a different file description now), so its	385	(because the fd could point to a different file description now), so its
365	best to avoid that. Also, C<dup ()>'ed file descriptors might not work	386	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
366	very well if you register events for both fds.	387	very well if you register events for both fds.
367		388
368	Please note that epoll sometimes generates spurious notifications, so you	389	Please note that epoll sometimes generates spurious notifications, so you
…		…
371		392
372	Best performance from this backend is achieved by not unregistering all	393	Best performance from this backend is achieved by not unregistering all
373	watchers for a file descriptor until it has been closed, if possible, i.e.	394	watchers for a file descriptor until it has been closed, if possible, i.e.
374	keep at least one watcher active per fd at all times.	395	keep at least one watcher active per fd at all times.
375		396
376	While nominally embeddeble in other event loops, this feature is broken in	397	While nominally embeddable in other event loops, this feature is broken in
377	all kernel versions tested so far.	398	all kernel versions tested so far.
378		399
379	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	400	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
380		401
381	Kqueue deserves special mention, as at the time of this writing, it	402	Kqueue deserves special mention, as at the time of this writing, it
382	was broken on all BSDs except NetBSD (usually it doesn't work reliably	403	was broken on all BSDs except NetBSD (usually it doesn't work reliably
383	with anything but sockets and pipes, except on Darwin, where of course	404	with anything but sockets and pipes, except on Darwin, where of course
384	it's completely useless). For this reason it's not being "autodetected"	405	it's completely useless). For this reason it's not being "auto-detected"
385	unless you explicitly specify it explicitly in the flags (i.e. using	406	unless you explicitly specify it explicitly in the flags (i.e. using
386	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)	407	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
387	system like NetBSD.	408	system like NetBSD.
388		409
389	You still can embed kqueue into a normal poll or select backend and use it	410	You still can embed kqueue into a normal poll or select backend and use it
…		…
391	the target platform). See C<ev_embed> watchers for more info.	412	the target platform). See C<ev_embed> watchers for more info.
392		413
393	It scales in the same way as the epoll backend, but the interface to the	414	It scales in the same way as the epoll backend, but the interface to the
394	kernel is more efficient (which says nothing about its actual speed, of	415	kernel is more efficient (which says nothing about its actual speed, of
395	course). While stopping, setting and starting an I/O watcher does never	416	course). While stopping, setting and starting an I/O watcher does never
396	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to	417	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
397	two event changes per incident, support for C<fork ()> is very bad and it	418	two event changes per incident, support for C<fork ()> is very bad and it
398	drops fds silently in similarly hard-to-detect cases.	419	drops fds silently in similarly hard-to-detect cases.
399		420
400	This backend usually performs well under most conditions.	421	This backend usually performs well under most conditions.
401		422
…		…
416	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	437	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
417		438
418	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	439	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
419	it's really slow, but it still scales very well (O(active_fds)).	440	it's really slow, but it still scales very well (O(active_fds)).
420		441
421	Please note that solaris event ports can deliver a lot of spurious	442	Please note that Solaris event ports can deliver a lot of spurious
422	notifications, so you need to use non-blocking I/O or other means to avoid	443	notifications, so you need to use non-blocking I/O or other means to avoid
423	blocking when no data (or space) is available.	444	blocking when no data (or space) is available.
424		445
425	While this backend scales well, it requires one system call per active	446	While this backend scales well, it requires one system call per active
426	file descriptor per loop iteration. For small and medium numbers of file	447	file descriptor per loop iteration. For small and medium numbers of file
427	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	448	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
428	might perform better.	449	might perform better.
429		450
430	On the positive side, ignoring the spurious readyness notifications, this	451	On the positive side, ignoring the spurious readiness notifications, this
431	backend actually performed to specification in all tests and is fully	452	backend actually performed to specification in all tests and is fully
432	embeddable, which is a rare feat among the OS-specific backends.	453	embeddable, which is a rare feat among the OS-specific backends.
433		454
434	=item C<EVBACKEND_ALL>	455	=item C<EVBACKEND_ALL>
435		456
…		…
439		460
440	It is definitely not recommended to use this flag.	461	It is definitely not recommended to use this flag.
441		462
442	=back	463	=back
443		464
444	If one or more of these are ored into the flags value, then only these	465	If one or more of these are or'ed into the flags value, then only these
445	backends will be tried (in the reverse order as listed here). If none are	466	backends will be tried (in the reverse order as listed here). If none are
446	specified, all backends in C<ev_recommended_backends ()> will be tried.	467	specified, all backends in C<ev_recommended_backends ()> will be tried.
447		468
448	The most typical usage is like this:	469	The most typical usage is like this:
449		470
450	if (!ev_default_loop (0))	471	if (!ev_default_loop (0))
451	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	472	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
452		473
453	Restrict libev to the select and poll backends, and do not allow	474	Restrict libev to the select and poll backends, and do not allow
454	environment settings to be taken into account:	475	environment settings to be taken into account:
455		476
456	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);	477	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
457		478
458	Use whatever libev has to offer, but make sure that kqueue is used if	479	Use whatever libev has to offer, but make sure that kqueue is used if
459	available (warning, breaks stuff, best use only with your own private	480	available (warning, breaks stuff, best use only with your own private
460	event loop and only if you know the OS supports your types of fds):	481	event loop and only if you know the OS supports your types of fds):
461		482
462	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	483	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
463		484
464	=item struct ev_loop *ev_loop_new (unsigned int flags)	485	=item struct ev_loop *ev_loop_new (unsigned int flags)
465		486
466	Similar to C<ev_default_loop>, but always creates a new event loop that is	487	Similar to C<ev_default_loop>, but always creates a new event loop that is
467	always distinct from the default loop. Unlike the default loop, it cannot	488	always distinct from the default loop. Unlike the default loop, it cannot
468	handle signal and child watchers, and attempts to do so will be greeted by	489	handle signal and child watchers, and attempts to do so will be greeted by
469	undefined behaviour (or a failed assertion if assertions are enabled).	490	undefined behaviour (or a failed assertion if assertions are enabled).
470		491
		492	Note that this function I<is> thread-safe, and the recommended way to use
		493	libev with threads is indeed to create one loop per thread, and using the
		494	default loop in the "main" or "initial" thread.
		495
471	Example: Try to create a event loop that uses epoll and nothing else.	496	Example: Try to create a event loop that uses epoll and nothing else.
472		497
473	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	498	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
474	if (!epoller)	499	if (!epoller)
475	fatal ("no epoll found here, maybe it hides under your chair");	500	fatal ("no epoll found here, maybe it hides under your chair");
476		501
477	=item ev_default_destroy ()	502	=item ev_default_destroy ()
478		503
479	Destroys the default loop again (frees all memory and kernel state	504	Destroys the default loop again (frees all memory and kernel state
480	etc.). None of the active event watchers will be stopped in the normal	505	etc.). None of the active event watchers will be stopped in the normal
481	sense, so e.g. C<ev_is_active> might still return true. It is your	506	sense, so e.g. C<ev_is_active> might still return true. It is your
482	responsibility to either stop all watchers cleanly yoursef I<before>	507	responsibility to either stop all watchers cleanly yourself I<before>
483	calling this function, or cope with the fact afterwards (which is usually	508	calling this function, or cope with the fact afterwards (which is usually
484	the easiest thing, you can just ignore the watchers and/or C<free ()> them	509	the easiest thing, you can just ignore the watchers and/or C<free ()> them
485	for example).	510	for example).
486		511
487	Note that certain global state, such as signal state, will not be freed by	512	Note that certain global state, such as signal state, will not be freed by
…		…
568	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	593	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle
569	those events and any outstanding ones, but will not block your process in	594	those events and any outstanding ones, but will not block your process in
570	case there are no events and will return after one iteration of the loop.	595	case there are no events and will return after one iteration of the loop.
571		596
572	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	597	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
573	neccessary) and will handle those and any outstanding ones. It will block	598	necessary) and will handle those and any outstanding ones. It will block
574	your process until at least one new event arrives, and will return after	599	your process until at least one new event arrives, and will return after
575	one iteration of the loop. This is useful if you are waiting for some	600	one iteration of the loop. This is useful if you are waiting for some
576	external event in conjunction with something not expressible using other	601	external event in conjunction with something not expressible using other
577	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	602	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
578	usually a better approach for this kind of thing.	603	usually a better approach for this kind of thing.
…		…
639	respectively).	664	respectively).
640		665
641	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	666	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
642	running when nothing else is active.	667	running when nothing else is active.
643		668
644	struct ev_signal exitsig;	669	struct ev_signal exitsig;
645	ev_signal_init (&exitsig, sig_cb, SIGINT);	670	ev_signal_init (&exitsig, sig_cb, SIGINT);
646	ev_signal_start (loop, &exitsig);	671	ev_signal_start (loop, &exitsig);
647	evf_unref (loop);	672	evf_unref (loop);
648		673
649	Example: For some weird reason, unregister the above signal handler again.	674	Example: For some weird reason, unregister the above signal handler again.
650		675
651	ev_ref (loop);	676	ev_ref (loop);
652	ev_signal_stop (loop, &exitsig);	677	ev_signal_stop (loop, &exitsig);
653		678
654	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	679	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
655		680
656	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	681	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
657		682
…		…
679	to spend more time collecting timeouts, at the expense of increased	704	to spend more time collecting timeouts, at the expense of increased
680	latency (the watcher callback will be called later). C<ev_io> watchers	705	latency (the watcher callback will be called later). C<ev_io> watchers
681	will not be affected. Setting this to a non-null value will not introduce	706	will not be affected. Setting this to a non-null value will not introduce
682	any overhead in libev.	707	any overhead in libev.
683		708
684	Many (busy) programs can usually benefit by setting the io collect	709	Many (busy) programs can usually benefit by setting the I/O collect
685	interval to a value near C<0.1> or so, which is often enough for	710	interval to a value near C<0.1> or so, which is often enough for
686	interactive servers (of course not for games), likewise for timeouts. It	711	interactive servers (of course not for games), likewise for timeouts. It
687	usually doesn't make much sense to set it to a lower value than C<0.01>,	712	usually doesn't make much sense to set it to a lower value than C<0.01>,
688	as this approsaches the timing granularity of most systems.	713	as this approaches the timing granularity of most systems.
		714
		715	=item ev_loop_verify (loop)
		716
		717	This function only does something when C<EV_VERIFY> support has been
		718	compiled in. It tries to go through all internal structures and checks
		719	them for validity. If anything is found to be inconsistent, it will print
		720	an error message to standard error and call C<abort ()>.
		721
		722	This can be used to catch bugs inside libev itself: under normal
		723	circumstances, this function will never abort as of course libev keeps its
		724	data structures consistent.
689		725
690	=back	726	=back
691		727
692		728
693	=head1 ANATOMY OF A WATCHER	729	=head1 ANATOMY OF A WATCHER
694		730
695	A watcher is a structure that you create and register to record your	731	A watcher is a structure that you create and register to record your
696	interest in some event. For instance, if you want to wait for STDIN to	732	interest in some event. For instance, if you want to wait for STDIN to
697	become readable, you would create an C<ev_io> watcher for that:	733	become readable, you would create an C<ev_io> watcher for that:
698		734
699	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	735	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
700	{	736	{
701	ev_io_stop (w);	737	ev_io_stop (w);
702	ev_unloop (loop, EVUNLOOP_ALL);	738	ev_unloop (loop, EVUNLOOP_ALL);
703	}	739	}
704		740
705	struct ev_loop *loop = ev_default_loop (0);	741	struct ev_loop *loop = ev_default_loop (0);
706	struct ev_io stdin_watcher;	742	struct ev_io stdin_watcher;
707	ev_init (&stdin_watcher, my_cb);	743	ev_init (&stdin_watcher, my_cb);
708	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	744	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
709	ev_io_start (loop, &stdin_watcher);	745	ev_io_start (loop, &stdin_watcher);
710	ev_loop (loop, 0);	746	ev_loop (loop, 0);
711		747
712	As you can see, you are responsible for allocating the memory for your	748	As you can see, you are responsible for allocating the memory for your
713	watcher structures (and it is usually a bad idea to do this on the stack,	749	watcher structures (and it is usually a bad idea to do this on the stack,
714	although this can sometimes be quite valid).	750	although this can sometimes be quite valid).
715		751
716	Each watcher structure must be initialised by a call to C<ev_init	752	Each watcher structure must be initialised by a call to C<ev_init
717	(watcher *, callback)>, which expects a callback to be provided. This	753	(watcher *, callback)>, which expects a callback to be provided. This
718	callback gets invoked each time the event occurs (or, in the case of io	754	callback gets invoked each time the event occurs (or, in the case of I/O
719	watchers, each time the event loop detects that the file descriptor given	755	watchers, each time the event loop detects that the file descriptor given
720	is readable and/or writable).	756	is readable and/or writable).
721		757
722	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	758	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro
723	with arguments specific to this watcher type. There is also a macro	759	with arguments specific to this watcher type. There is also a macro
…		…
799		835
800	The given async watcher has been asynchronously notified (see C<ev_async>).	836	The given async watcher has been asynchronously notified (see C<ev_async>).
801		837
802	=item C<EV_ERROR>	838	=item C<EV_ERROR>
803		839
804	An unspecified error has occured, the watcher has been stopped. This might	840	An unspecified error has occurred, the watcher has been stopped. This might
805	happen because the watcher could not be properly started because libev	841	happen because the watcher could not be properly started because libev
806	ran out of memory, a file descriptor was found to be closed or any other	842	ran out of memory, a file descriptor was found to be closed or any other
807	problem. You best act on it by reporting the problem and somehow coping	843	problem. You best act on it by reporting the problem and somehow coping
808	with the watcher being stopped.	844	with the watcher being stopped.
809		845
810	Libev will usually signal a few "dummy" events together with an error,	846	Libev will usually signal a few "dummy" events together with an error,
811	for example it might indicate that a fd is readable or writable, and if	847	for example it might indicate that a fd is readable or writable, and if
812	your callbacks is well-written it can just attempt the operation and cope	848	your callbacks is well-written it can just attempt the operation and cope
813	with the error from read() or write(). This will not work in multithreaded	849	with the error from read() or write(). This will not work in multi-threaded
814	programs, though, so beware.	850	programs, though, so beware.
815		851
816	=back	852	=back
817		853
818	=head2 GENERIC WATCHER FUNCTIONS	854	=head2 GENERIC WATCHER FUNCTIONS
…		…
848	Although some watcher types do not have type-specific arguments	884	Although some watcher types do not have type-specific arguments
849	(e.g. C<ev_prepare>) you still need to call its C<set> macro.	885	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
850		886
851	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	887	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
852		888
853	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	889	This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
854	calls into a single call. This is the most convinient method to initialise	890	calls into a single call. This is the most convenient method to initialise
855	a watcher. The same limitations apply, of course.	891	a watcher. The same limitations apply, of course.
856		892
857	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	893	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
858		894
859	Starts (activates) the given watcher. Only active watchers will receive	895	Starts (activates) the given watcher. Only active watchers will receive
…		…
942	to associate arbitrary data with your watcher. If you need more data and	978	to associate arbitrary data with your watcher. If you need more data and
943	don't want to allocate memory and store a pointer to it in that data	979	don't want to allocate memory and store a pointer to it in that data
944	member, you can also "subclass" the watcher type and provide your own	980	member, you can also "subclass" the watcher type and provide your own
945	data:	981	data:
946		982
947	struct my_io	983	struct my_io
948	{	984	{
949	struct ev_io io;	985	struct ev_io io;
950	int otherfd;	986	int otherfd;
951	void *somedata;	987	void *somedata;
952	struct whatever *mostinteresting;	988	struct whatever *mostinteresting;
953	}	989	}
954		990
955	And since your callback will be called with a pointer to the watcher, you	991	And since your callback will be called with a pointer to the watcher, you
956	can cast it back to your own type:	992	can cast it back to your own type:
957		993
958	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	994	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
959	{	995	{
960	struct my_io *w = (struct my_io *)w_;	996	struct my_io *w = (struct my_io *)w_;
961	...	997	...
962	}	998	}
963		999
964	More interesting and less C-conformant ways of casting your callback type	1000	More interesting and less C-conformant ways of casting your callback type
965	instead have been omitted.	1001	instead have been omitted.
966		1002
967	Another common scenario is having some data structure with multiple	1003	Another common scenario is having some data structure with multiple
968	watchers:	1004	watchers:
969		1005
970	struct my_biggy	1006	struct my_biggy
971	{	1007	{
972	int some_data;	1008	int some_data;
973	ev_timer t1;	1009	ev_timer t1;
974	ev_timer t2;	1010	ev_timer t2;
975	}	1011	}
976		1012
977	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1013	In this case getting the pointer to C<my_biggy> is a bit more complicated,
978	you need to use C<offsetof>:	1014	you need to use C<offsetof>:
979		1015
980	#include <stddef.h>	1016	#include <stddef.h>
981		1017
982	static void	1018	static void
983	t1_cb (EV_P_ struct ev_timer *w, int revents)	1019	t1_cb (EV_P_ struct ev_timer *w, int revents)
984	{	1020	{
985	struct my_biggy big = (struct my_biggy *	1021	struct my_biggy big = (struct my_biggy *
986	(((char *)w) - offsetof (struct my_biggy, t1));	1022	(((char *)w) - offsetof (struct my_biggy, t1));
987	}	1023	}
988		1024
989	static void	1025	static void
990	t2_cb (EV_P_ struct ev_timer *w, int revents)	1026	t2_cb (EV_P_ struct ev_timer *w, int revents)
991	{	1027	{
992	struct my_biggy big = (struct my_biggy *	1028	struct my_biggy big = (struct my_biggy *
993	(((char *)w) - offsetof (struct my_biggy, t2));	1029	(((char *)w) - offsetof (struct my_biggy, t2));
994	}	1030	}
995		1031
996		1032
997	=head1 WATCHER TYPES	1033	=head1 WATCHER TYPES
998		1034
999	This section describes each watcher in detail, but will not repeat	1035	This section describes each watcher in detail, but will not repeat
…		…
1028	If you must do this, then force the use of a known-to-be-good backend	1064	If you must do this, then force the use of a known-to-be-good backend
1029	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1065	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
1030	C<EVBACKEND_POLL>).	1066	C<EVBACKEND_POLL>).
1031		1067
1032	Another thing you have to watch out for is that it is quite easy to	1068	Another thing you have to watch out for is that it is quite easy to
1033	receive "spurious" readyness notifications, that is your callback might	1069	receive "spurious" readiness notifications, that is your callback might
1034	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1070	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1035	because there is no data. Not only are some backends known to create a	1071	because there is no data. Not only are some backends known to create a
1036	lot of those (for example solaris ports), it is very easy to get into	1072	lot of those (for example Solaris ports), it is very easy to get into
1037	this situation even with a relatively standard program structure. Thus	1073	this situation even with a relatively standard program structure. Thus
1038	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1074	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1039	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1075	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1040		1076
1041	If you cannot run the fd in non-blocking mode (for example you should not	1077	If you cannot run the fd in non-blocking mode (for example you should not
1042	play around with an Xlib connection), then you have to seperately re-test	1078	play around with an Xlib connection), then you have to separately re-test
1043	whether a file descriptor is really ready with a known-to-be good interface	1079	whether a file descriptor is really ready with a known-to-be good interface
1044	such as poll (fortunately in our Xlib example, Xlib already does this on	1080	such as poll (fortunately in our Xlib example, Xlib already does this on
1045	its own, so its quite safe to use).	1081	its own, so its quite safe to use).
1046		1082
1047	=head3 The special problem of disappearing file descriptors	1083	=head3 The special problem of disappearing file descriptors
…		…
1085	To support fork in your programs, you either have to call	1121	To support fork in your programs, you either have to call
1086	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,	1122	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
1087	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or	1123	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
1088	C<EVBACKEND_POLL>.	1124	C<EVBACKEND_POLL>.
1089		1125
		1126	=head3 The special problem of SIGPIPE
		1127
		1128	While not really specific to libev, it is easy to forget about SIGPIPE:
		1129	when reading from a pipe whose other end has been closed, your program
		1130	gets send a SIGPIPE, which, by default, aborts your program. For most
		1131	programs this is sensible behaviour, for daemons, this is usually
		1132	undesirable.
		1133
		1134	So when you encounter spurious, unexplained daemon exits, make sure you
		1135	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
		1136	somewhere, as that would have given you a big clue).
		1137
1090		1138
1091	=head3 Watcher-Specific Functions	1139	=head3 Watcher-Specific Functions
1092		1140
1093	=over 4	1141	=over 4
1094		1142
1095	=item ev_io_init (ev_io *, callback, int fd, int events)	1143	=item ev_io_init (ev_io *, callback, int fd, int events)
1096		1144
1097	=item ev_io_set (ev_io *, int fd, int events)	1145	=item ev_io_set (ev_io *, int fd, int events)
1098		1146
1099	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1147	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1100	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1148	receive events for and events is either C<EV_READ>, C<EV_WRITE> or
1101	C<EV_READ | EV_WRITE> to receive the given events.	1149	C<EV_READ | EV_WRITE> to receive the given events.
1102		1150
1103	=item int fd [read-only]	1151	=item int fd [read-only]
1104		1152
1105	The file descriptor being watched.	1153	The file descriptor being watched.
…		…
1114		1162
1115	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1163	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1116	readable, but only once. Since it is likely line-buffered, you could	1164	readable, but only once. Since it is likely line-buffered, you could
1117	attempt to read a whole line in the callback.	1165	attempt to read a whole line in the callback.
1118		1166
1119	static void	1167	static void
1120	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1168	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1121	{	1169	{
1122	ev_io_stop (loop, w);	1170	ev_io_stop (loop, w);
1123	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1171	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1124	}	1172	}
1125		1173
1126	...	1174	...
1127	struct ev_loop *loop = ev_default_init (0);	1175	struct ev_loop *loop = ev_default_init (0);
1128	struct ev_io stdin_readable;	1176	struct ev_io stdin_readable;
1129	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1177	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1130	ev_io_start (loop, &stdin_readable);	1178	ev_io_start (loop, &stdin_readable);
1131	ev_loop (loop, 0);	1179	ev_loop (loop, 0);
1132		1180
1133		1181
1134	=head2 C<ev_timer> - relative and optionally repeating timeouts	1182	=head2 C<ev_timer> - relative and optionally repeating timeouts
1135		1183
1136	Timer watchers are simple relative timers that generate an event after a	1184	Timer watchers are simple relative timers that generate an event after a
1137	given time, and optionally repeating in regular intervals after that.	1185	given time, and optionally repeating in regular intervals after that.
1138		1186
1139	The timers are based on real time, that is, if you register an event that	1187	The timers are based on real time, that is, if you register an event that
1140	times out after an hour and you reset your system clock to last years	1188	times out after an hour and you reset your system clock to January last
1141	time, it will still time out after (roughly) and hour. "Roughly" because	1189	year, it will still time out after (roughly) and hour. "Roughly" because
1142	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1190	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1143	monotonic clock option helps a lot here).	1191	monotonic clock option helps a lot here).
1144		1192
1145	The relative timeouts are calculated relative to the C<ev_now ()>	1193	The relative timeouts are calculated relative to the C<ev_now ()>
1146	time. This is usually the right thing as this timestamp refers to the time	1194	time. This is usually the right thing as this timestamp refers to the time
…		…
1148	you suspect event processing to be delayed and you I<need> to base the timeout	1196	you suspect event processing to be delayed and you I<need> to base the timeout
1149	on the current time, use something like this to adjust for this:	1197	on the current time, use something like this to adjust for this:
1150		1198
1151	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1199	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1152		1200
1153	The callback is guarenteed to be invoked only when its timeout has passed,	1201	The callback is guaranteed to be invoked only after its timeout has passed,
1154	but if multiple timers become ready during the same loop iteration then	1202	but if multiple timers become ready during the same loop iteration then
1155	order of execution is undefined.	1203	order of execution is undefined.
1156		1204
1157	=head3 Watcher-Specific Functions and Data Members	1205	=head3 Watcher-Specific Functions and Data Members
1158		1206
…		…
1160		1208
1161	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1209	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1162		1210
1163	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1211	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1164		1212
1165	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1213	Configure the timer to trigger after C<after> seconds. If C<repeat>
1166	C<0.>, then it will automatically be stopped. If it is positive, then the	1214	is C<0.>, then it will automatically be stopped once the timeout is
1167	timer will automatically be configured to trigger again C<repeat> seconds	1215	reached. If it is positive, then the timer will automatically be
1168	later, again, and again, until stopped manually.	1216	configured to trigger again C<repeat> seconds later, again, and again,
		1217	until stopped manually.
1169		1218
1170	The timer itself will do a best-effort at avoiding drift, that is, if you	1219	The timer itself will do a best-effort at avoiding drift, that is, if
1171	configure a timer to trigger every 10 seconds, then it will trigger at	1220	you configure a timer to trigger every 10 seconds, then it will normally
1172	exactly 10 second intervals. If, however, your program cannot keep up with	1221	trigger at exactly 10 second intervals. If, however, your program cannot
1173	the timer (because it takes longer than those 10 seconds to do stuff) the	1222	keep up with the timer (because it takes longer than those 10 seconds to
1174	timer will not fire more than once per event loop iteration.	1223	do stuff) the timer will not fire more than once per event loop iteration.
1175		1224
1176	=item ev_timer_again (loop, ev_timer *)	1225	=item ev_timer_again (loop, ev_timer *)
1177		1226
1178	This will act as if the timer timed out and restart it again if it is	1227	This will act as if the timer timed out and restart it again if it is
1179	repeating. The exact semantics are:	1228	repeating. The exact semantics are:
1180		1229
1181	If the timer is pending, its pending status is cleared.	1230	If the timer is pending, its pending status is cleared.
1182		1231
1183	If the timer is started but nonrepeating, stop it (as if it timed out).	1232	If the timer is started but non-repeating, stop it (as if it timed out).
1184		1233
1185	If the timer is repeating, either start it if necessary (with the	1234	If the timer is repeating, either start it if necessary (with the
1186	C<repeat> value), or reset the running timer to the C<repeat> value.	1235	C<repeat> value), or reset the running timer to the C<repeat> value.
1187		1236
1188	This sounds a bit complicated, but here is a useful and typical	1237	This sounds a bit complicated, but here is a useful and typical
1189	example: Imagine you have a tcp connection and you want a so-called idle	1238	example: Imagine you have a TCP connection and you want a so-called idle
1190	timeout, that is, you want to be called when there have been, say, 60	1239	timeout, that is, you want to be called when there have been, say, 60
1191	seconds of inactivity on the socket. The easiest way to do this is to	1240	seconds of inactivity on the socket. The easiest way to do this is to
1192	configure an C<ev_timer> with a C<repeat> value of C<60> and then call	1241	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1193	C<ev_timer_again> each time you successfully read or write some data. If	1242	C<ev_timer_again> each time you successfully read or write some data. If
1194	you go into an idle state where you do not expect data to travel on the	1243	you go into an idle state where you do not expect data to travel on the
…		…
1220		1269
1221	=head3 Examples	1270	=head3 Examples
1222		1271
1223	Example: Create a timer that fires after 60 seconds.	1272	Example: Create a timer that fires after 60 seconds.
1224		1273
1225	static void	1274	static void
1226	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1275	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1227	{	1276	{
1228	.. one minute over, w is actually stopped right here	1277	.. one minute over, w is actually stopped right here
1229	}	1278	}
1230		1279
1231	struct ev_timer mytimer;	1280	struct ev_timer mytimer;
1232	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1281	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1233	ev_timer_start (loop, &mytimer);	1282	ev_timer_start (loop, &mytimer);
1234		1283
1235	Example: Create a timeout timer that times out after 10 seconds of	1284	Example: Create a timeout timer that times out after 10 seconds of
1236	inactivity.	1285	inactivity.
1237		1286
1238	static void	1287	static void
1239	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1288	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1240	{	1289	{
1241	.. ten seconds without any activity	1290	.. ten seconds without any activity
1242	}	1291	}
1243		1292
1244	struct ev_timer mytimer;	1293	struct ev_timer mytimer;
1245	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1294	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1246	ev_timer_again (&mytimer); /* start timer */	1295	ev_timer_again (&mytimer); /* start timer */
1247	ev_loop (loop, 0);	1296	ev_loop (loop, 0);
1248		1297
1249	// and in some piece of code that gets executed on any "activity":	1298	// and in some piece of code that gets executed on any "activity":
1250	// reset the timeout to start ticking again at 10 seconds	1299	// reset the timeout to start ticking again at 10 seconds
1251	ev_timer_again (&mytimer);	1300	ev_timer_again (&mytimer);
1252		1301
1253		1302
1254	=head2 C<ev_periodic> - to cron or not to cron?	1303	=head2 C<ev_periodic> - to cron or not to cron?
1255		1304
1256	Periodic watchers are also timers of a kind, but they are very versatile	1305	Periodic watchers are also timers of a kind, but they are very versatile
1257	(and unfortunately a bit complex).	1306	(and unfortunately a bit complex).
1258		1307
1259	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1308	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
1260	but on wallclock time (absolute time). You can tell a periodic watcher	1309	but on wall clock time (absolute time). You can tell a periodic watcher
1261	to trigger "at" some specific point in time. For example, if you tell a	1310	to trigger after some specific point in time. For example, if you tell a
1262	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1311	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()
1263	+ 10.>) and then reset your system clock to the last year, then it will	1312	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1313	clock to January of the previous year, then it will take more than year
1264	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1314	to trigger the event (unlike an C<ev_timer>, which would still trigger
1265	roughly 10 seconds later).	1315	roughly 10 seconds later as it uses a relative timeout).
1266		1316
1267	They can also be used to implement vastly more complex timers, such as	1317	C<ev_periodic>s can also be used to implement vastly more complex timers,
1268	triggering an event on each midnight, local time or other, complicated,	1318	such as triggering an event on each "midnight, local time", or other
1269	rules.	1319	complicated, rules.
1270		1320
1271	As with timers, the callback is guarenteed to be invoked only when the	1321	As with timers, the callback is guaranteed to be invoked only when the
1272	time (C<at>) has been passed, but if multiple periodic timers become ready	1322	time (C<at>) has passed, but if multiple periodic timers become ready
1273	during the same loop iteration then order of execution is undefined.	1323	during the same loop iteration then order of execution is undefined.
1274		1324
1275	=head3 Watcher-Specific Functions and Data Members	1325	=head3 Watcher-Specific Functions and Data Members
1276		1326
1277	=over 4	1327	=over 4
…		…
1285		1335
1286	=over 4	1336	=over 4
1287		1337
1288	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1338	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1289		1339
1290	In this configuration the watcher triggers an event at the wallclock time	1340	In this configuration the watcher triggers an event after the wall clock
1291	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1341	time C<at> has passed and doesn't repeat. It will not adjust when a time
1292	that is, if it is to be run at January 1st 2011 then it will run when the	1342	jump occurs, that is, if it is to be run at January 1st 2011 then it will
1293	system time reaches or surpasses this time.	1343	run when the system time reaches or surpasses this time.
1294		1344
1295	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1345	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1296		1346
1297	In this mode the watcher will always be scheduled to time out at the next	1347	In this mode the watcher will always be scheduled to time out at the next
1298	C<at + N * interval> time (for some integer N, which can also be negative)	1348	C<at + N * interval> time (for some integer N, which can also be negative)
1299	and then repeat, regardless of any time jumps.	1349	and then repeat, regardless of any time jumps.
1300		1350
1301	This can be used to create timers that do not drift with respect to system	1351	This can be used to create timers that do not drift with respect to system
1302	time:	1352	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1353	the hour:
1303		1354
1304	ev_periodic_set (&periodic, 0., 3600., 0);	1355	ev_periodic_set (&periodic, 0., 3600., 0);
1305		1356
1306	This doesn't mean there will always be 3600 seconds in between triggers,	1357	This doesn't mean there will always be 3600 seconds in between triggers,
1307	but only that the the callback will be called when the system time shows a	1358	but only that the callback will be called when the system time shows a
1308	full hour (UTC), or more correctly, when the system time is evenly divisible	1359	full hour (UTC), or more correctly, when the system time is evenly divisible
1309	by 3600.	1360	by 3600.
1310		1361
1311	Another way to think about it (for the mathematically inclined) is that	1362	Another way to think about it (for the mathematically inclined) is that
1312	C<ev_periodic> will try to run the callback in this mode at the next possible	1363	C<ev_periodic> will try to run the callback in this mode at the next possible
1313	time where C<time = at (mod interval)>, regardless of any time jumps.	1364	time where C<time = at (mod interval)>, regardless of any time jumps.
1314		1365
1315	For numerical stability it is preferable that the C<at> value is near	1366	For numerical stability it is preferable that the C<at> value is near
1316	C<ev_now ()> (the current time), but there is no range requirement for	1367	C<ev_now ()> (the current time), but there is no range requirement for
1317	this value.	1368	this value, and in fact is often specified as zero.
		1369
		1370	Note also that there is an upper limit to how often a timer can fire (CPU
		1371	speed for example), so if C<interval> is very small then timing stability
		1372	will of course deteriorate. Libev itself tries to be exact to be about one
		1373	millisecond (if the OS supports it and the machine is fast enough).
1318		1374
1319	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1375	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1320		1376
1321	In this mode the values for C<interval> and C<at> are both being	1377	In this mode the values for C<interval> and C<at> are both being
1322	ignored. Instead, each time the periodic watcher gets scheduled, the	1378	ignored. Instead, each time the periodic watcher gets scheduled, the
1323	reschedule callback will be called with the watcher as first, and the	1379	reschedule callback will be called with the watcher as first, and the
1324	current time as second argument.	1380	current time as second argument.
1325		1381
1326	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1382	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1327	ever, or make any event loop modifications>. If you need to stop it,	1383	ever, or make ANY event loop modifications whatsoever>.
1328	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1329	starting an C<ev_prepare> watcher, which is legal).
1330		1384
		1385	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1386	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1387	only event loop modification you are allowed to do).
		1388
1331	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1389	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1332	ev_tstamp now)>, e.g.:	1390	*w, ev_tstamp now)>, e.g.:
1333		1391
1334	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1392	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1335	{	1393	{
1336	return now + 60.;	1394	return now + 60.;
1337	}	1395	}
…		…
1339	It must return the next time to trigger, based on the passed time value	1397	It must return the next time to trigger, based on the passed time value
1340	(that is, the lowest time value larger than to the second argument). It	1398	(that is, the lowest time value larger than to the second argument). It
1341	will usually be called just before the callback will be triggered, but	1399	will usually be called just before the callback will be triggered, but
1342	might be called at other times, too.	1400	might be called at other times, too.
1343		1401
1344	NOTE: I<< This callback must always return a time that is later than the	1402	NOTE: I<< This callback must always return a time that is higher than or
1345	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.	1403	equal to the passed C<now> value >>.
1346		1404
1347	This can be used to create very complex timers, such as a timer that	1405	This can be used to create very complex timers, such as a timer that
1348	triggers on each midnight, local time. To do this, you would calculate the	1406	triggers on "next midnight, local time". To do this, you would calculate the
1349	next midnight after C<now> and return the timestamp value for this. How	1407	next midnight after C<now> and return the timestamp value for this. How
1350	you do this is, again, up to you (but it is not trivial, which is the main	1408	you do this is, again, up to you (but it is not trivial, which is the main
1351	reason I omitted it as an example).	1409	reason I omitted it as an example).
1352		1410
1353	=back	1411	=back
…		…
1357	Simply stops and restarts the periodic watcher again. This is only useful	1415	Simply stops and restarts the periodic watcher again. This is only useful
1358	when you changed some parameters or the reschedule callback would return	1416	when you changed some parameters or the reschedule callback would return
1359	a different time than the last time it was called (e.g. in a crond like	1417	a different time than the last time it was called (e.g. in a crond like
1360	program when the crontabs have changed).	1418	program when the crontabs have changed).
1361		1419
		1420	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1421
		1422	When active, returns the absolute time that the watcher is supposed to
		1423	trigger next.
		1424
1362	=item ev_tstamp offset [read-write]	1425	=item ev_tstamp offset [read-write]
1363		1426
1364	When repeating, this contains the offset value, otherwise this is the	1427	When repeating, this contains the offset value, otherwise this is the
1365	absolute point in time (the C<at> value passed to C<ev_periodic_set>).	1428	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1366		1429
…		…
1377		1440
1378	The current reschedule callback, or C<0>, if this functionality is	1441	The current reschedule callback, or C<0>, if this functionality is
1379	switched off. Can be changed any time, but changes only take effect when	1442	switched off. Can be changed any time, but changes only take effect when
1380	the periodic timer fires or C<ev_periodic_again> is being called.	1443	the periodic timer fires or C<ev_periodic_again> is being called.
1381		1444
1382	=item ev_tstamp at [read-only]
1383
1384	When active, contains the absolute time that the watcher is supposed to
1385	trigger next.
1386
1387	=back	1445	=back
1388		1446
1389	=head3 Examples	1447	=head3 Examples
1390		1448
1391	Example: Call a callback every hour, or, more precisely, whenever the	1449	Example: Call a callback every hour, or, more precisely, whenever the
1392	system clock is divisible by 3600. The callback invocation times have	1450	system clock is divisible by 3600. The callback invocation times have
1393	potentially a lot of jittering, but good long-term stability.	1451	potentially a lot of jitter, but good long-term stability.
1394		1452
1395	static void	1453	static void
1396	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1454	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1397	{	1455	{
1398	... its now a full hour (UTC, or TAI or whatever your clock follows)	1456	... its now a full hour (UTC, or TAI or whatever your clock follows)
1399	}	1457	}
1400		1458
1401	struct ev_periodic hourly_tick;	1459	struct ev_periodic hourly_tick;
1402	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1460	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1403	ev_periodic_start (loop, &hourly_tick);	1461	ev_periodic_start (loop, &hourly_tick);
1404		1462
1405	Example: The same as above, but use a reschedule callback to do it:	1463	Example: The same as above, but use a reschedule callback to do it:
1406		1464
1407	#include <math.h>	1465	#include <math.h>
1408		1466
1409	static ev_tstamp	1467	static ev_tstamp
1410	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1468	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1411	{	1469	{
1412	return fmod (now, 3600.) + 3600.;	1470	return fmod (now, 3600.) + 3600.;
1413	}	1471	}
1414		1472
1415	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1473	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1416		1474
1417	Example: Call a callback every hour, starting now:	1475	Example: Call a callback every hour, starting now:
1418		1476
1419	struct ev_periodic hourly_tick;	1477	struct ev_periodic hourly_tick;
1420	ev_periodic_init (&hourly_tick, clock_cb,	1478	ev_periodic_init (&hourly_tick, clock_cb,
1421	fmod (ev_now (loop), 3600.), 3600., 0);	1479	fmod (ev_now (loop), 3600.), 3600., 0);
1422	ev_periodic_start (loop, &hourly_tick);	1480	ev_periodic_start (loop, &hourly_tick);
1423		1481
1424		1482
1425	=head2 C<ev_signal> - signal me when a signal gets signalled!	1483	=head2 C<ev_signal> - signal me when a signal gets signalled!
1426		1484
1427	Signal watchers will trigger an event when the process receives a specific	1485	Signal watchers will trigger an event when the process receives a specific
…		…
1435	as you don't register any with libev). Similarly, when the last signal	1493	as you don't register any with libev). Similarly, when the last signal
1436	watcher for a signal is stopped libev will reset the signal handler to	1494	watcher for a signal is stopped libev will reset the signal handler to
1437	SIG_DFL (regardless of what it was set to before).	1495	SIG_DFL (regardless of what it was set to before).
1438		1496
1439	If possible and supported, libev will install its handlers with	1497	If possible and supported, libev will install its handlers with
1440	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1498	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1441	interrupted. If you have a problem with syscalls getting interrupted by	1499	interrupted. If you have a problem with system calls getting interrupted by
1442	signals you can block all signals in an C<ev_check> watcher and unblock	1500	signals you can block all signals in an C<ev_check> watcher and unblock
1443	them in an C<ev_prepare> watcher.	1501	them in an C<ev_prepare> watcher.
1444		1502
1445	=head3 Watcher-Specific Functions and Data Members	1503	=head3 Watcher-Specific Functions and Data Members
1446		1504
…		…
1461		1519
1462	=head3 Examples	1520	=head3 Examples
1463		1521
1464	Example: Try to exit cleanly on SIGINT and SIGTERM.	1522	Example: Try to exit cleanly on SIGINT and SIGTERM.
1465		1523
1466	static void	1524	static void
1467	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1525	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1468	{	1526	{
1469	ev_unloop (loop, EVUNLOOP_ALL);	1527	ev_unloop (loop, EVUNLOOP_ALL);
1470	}	1528	}
1471		1529
1472	struct ev_signal signal_watcher;	1530	struct ev_signal signal_watcher;
1473	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1531	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1474	ev_signal_start (loop, &sigint_cb);	1532	ev_signal_start (loop, &sigint_cb);
1475		1533
1476		1534
1477	=head2 C<ev_child> - watch out for process status changes	1535	=head2 C<ev_child> - watch out for process status changes
1478		1536
1479	Child watchers trigger when your process receives a SIGCHLD in response to	1537	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1481	is permissible to install a child watcher I<after> the child has been	1539	is permissible to install a child watcher I<after> the child has been
1482	forked (which implies it might have already exited), as long as the event	1540	forked (which implies it might have already exited), as long as the event
1483	loop isn't entered (or is continued from a watcher).	1541	loop isn't entered (or is continued from a watcher).
1484		1542
1485	Only the default event loop is capable of handling signals, and therefore	1543	Only the default event loop is capable of handling signals, and therefore
1486	you can only rgeister child watchers in the default event loop.	1544	you can only register child watchers in the default event loop.
1487		1545
1488	=head3 Process Interaction	1546	=head3 Process Interaction
1489		1547
1490	Libev grabs C<SIGCHLD> as soon as the default event loop is	1548	Libev grabs C<SIGCHLD> as soon as the default event loop is
1491	initialised. This is necessary to guarantee proper behaviour even if	1549	initialised. This is necessary to guarantee proper behaviour even if
1492	the first child watcher is started after the child exits. The occurance	1550	the first child watcher is started after the child exits. The occurrence
1493	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1551	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1494	synchronously as part of the event loop processing. Libev always reaps all	1552	synchronously as part of the event loop processing. Libev always reaps all
1495	children, even ones not watched.	1553	children, even ones not watched.
1496		1554
1497	=head3 Overriding the Built-In Processing	1555	=head3 Overriding the Built-In Processing
…		…
1539	=head3 Examples	1597	=head3 Examples
1540		1598
1541	Example: C<fork()> a new process and install a child handler to wait for	1599	Example: C<fork()> a new process and install a child handler to wait for
1542	its completion.	1600	its completion.
1543		1601
1544	ev_child cw;	1602	ev_child cw;
1545		1603
1546	static void	1604	static void
1547	child_cb (EV_P_ struct ev_child *w, int revents)	1605	child_cb (EV_P_ struct ev_child *w, int revents)
1548	{	1606	{
1549	ev_child_stop (EV_A_ w);	1607	ev_child_stop (EV_A_ w);
1550	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1608	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1551	}	1609	}
1552		1610
1553	pid_t pid = fork ();	1611	pid_t pid = fork ();
1554		1612
1555	if (pid < 0)	1613	if (pid < 0)
1556	// error	1614	// error
1557	else if (pid == 0)	1615	else if (pid == 0)
1558	{	1616	{
1559	// the forked child executes here	1617	// the forked child executes here
1560	exit (1);	1618	exit (1);
1561	}	1619	}
1562	else	1620	else
1563	{	1621	{
1564	ev_child_init (&cw, child_cb, pid, 0);	1622	ev_child_init (&cw, child_cb, pid, 0);
1565	ev_child_start (EV_DEFAULT_ &cw);	1623	ev_child_start (EV_DEFAULT_ &cw);
1566	}	1624	}
1567		1625
1568		1626
1569	=head2 C<ev_stat> - did the file attributes just change?	1627	=head2 C<ev_stat> - did the file attributes just change?
1570		1628
1571	This watches a filesystem path for attribute changes. That is, it calls	1629	This watches a file system path for attribute changes. That is, it calls
1572	C<stat> regularly (or when the OS says it changed) and sees if it changed	1630	C<stat> regularly (or when the OS says it changed) and sees if it changed
1573	compared to the last time, invoking the callback if it did.	1631	compared to the last time, invoking the callback if it did.
1574		1632
1575	The path does not need to exist: changing from "path exists" to "path does	1633	The path does not need to exist: changing from "path exists" to "path does
1576	not exist" is a status change like any other. The condition "path does	1634	not exist" is a status change like any other. The condition "path does
…		…
1594	as even with OS-supported change notifications, this can be	1652	as even with OS-supported change notifications, this can be
1595	resource-intensive.	1653	resource-intensive.
1596		1654
1597	At the time of this writing, only the Linux inotify interface is	1655	At the time of this writing, only the Linux inotify interface is
1598	implemented (implementing kqueue support is left as an exercise for the	1656	implemented (implementing kqueue support is left as an exercise for the
		1657	reader, note, however, that the author sees no way of implementing ev_stat
1599	reader). Inotify will be used to give hints only and should not change the	1658	semantics with kqueue). Inotify will be used to give hints only and should
1600	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1659	not change the semantics of C<ev_stat> watchers, which means that libev
1601	to fall back to regular polling again even with inotify, but changes are	1660	sometimes needs to fall back to regular polling again even with inotify,
1602	usually detected immediately, and if the file exists there will be no	1661	but changes are usually detected immediately, and if the file exists there
1603	polling.	1662	will be no polling.
		1663
		1664	=head3 ABI Issues (Largefile Support)
		1665
		1666	Libev by default (unless the user overrides this) uses the default
		1667	compilation environment, which means that on systems with large file
		1668	support disabled by default, you get the 32 bit version of the stat
		1669	structure. When using the library from programs that change the ABI to
		1670	use 64 bit file offsets the programs will fail. In that case you have to
		1671	compile libev with the same flags to get binary compatibility. This is
		1672	obviously the case with any flags that change the ABI, but the problem is
		1673	most noticeably disabled with ev_stat and large file support.
		1674
		1675	The solution for this is to lobby your distribution maker to make large
		1676	file interfaces available by default (as e.g. FreeBSD does) and not
		1677	optional. Libev cannot simply switch on large file support because it has
		1678	to exchange stat structures with application programs compiled using the
		1679	default compilation environment.
1604		1680
1605	=head3 Inotify	1681	=head3 Inotify
1606		1682
1607	When C<inotify (7)> support has been compiled into libev (generally only	1683	When C<inotify (7)> support has been compiled into libev (generally only
1608	available on Linux) and present at runtime, it will be used to speed up	1684	available on Linux) and present at runtime, it will be used to speed up
1609	change detection where possible. The inotify descriptor will be created lazily	1685	change detection where possible. The inotify descriptor will be created lazily
1610	when the first C<ev_stat> watcher is being started.	1686	when the first C<ev_stat> watcher is being started.
1611		1687
1612	Inotify presense does not change the semantics of C<ev_stat> watchers	1688	Inotify presence does not change the semantics of C<ev_stat> watchers
1613	except that changes might be detected earlier, and in some cases, to avoid	1689	except that changes might be detected earlier, and in some cases, to avoid
1614	making regular C<stat> calls. Even in the presense of inotify support	1690	making regular C<stat> calls. Even in the presence of inotify support
1615	there are many cases where libev has to resort to regular C<stat> polling.	1691	there are many cases where libev has to resort to regular C<stat> polling.
1616		1692
1617	(There is no support for kqueue, as apparently it cannot be used to	1693	(There is no support for kqueue, as apparently it cannot be used to
1618	implement this functionality, due to the requirement of having a file	1694	implement this functionality, due to the requirement of having a file
1619	descriptor open on the object at all times).	1695	descriptor open on the object at all times).
1620		1696
1621	=head3 The special problem of stat time resolution	1697	=head3 The special problem of stat time resolution
1622		1698
1623	The C<stat ()> syscall only supports full-second resolution portably, and	1699	The C<stat ()> system call only supports full-second resolution portably, and
1624	even on systems where the resolution is higher, many filesystems still	1700	even on systems where the resolution is higher, many file systems still
1625	only support whole seconds.	1701	only support whole seconds.
1626		1702
1627	That means that, if the time is the only thing that changes, you might	1703	That means that, if the time is the only thing that changes, you can
1628	miss updates: on the first update, C<ev_stat> detects a change and calls	1704	easily miss updates: on the first update, C<ev_stat> detects a change and
1629	your callback, which does something. When there is another update within	1705	calls your callback, which does something. When there is another update
1630	the same second, C<ev_stat> will be unable to detect it.	1706	within the same second, C<ev_stat> will be unable to detect it as the stat
		1707	data does not change.
1631		1708
1632	The solution to this is to delay acting on a change for a second (or till	1709	The solution to this is to delay acting on a change for slightly more
1633	the next second boundary), using a roughly one-second delay C<ev_timer>	1710	than a second (or till slightly after the next full second boundary), using
1634	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>	1711	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);
1635	is added to work around small timing inconsistencies of some operating	1712	ev_timer_again (loop, w)>).
1636	systems.	1713
		1714	The C<.02> offset is added to work around small timing inconsistencies
		1715	of some operating systems (where the second counter of the current time
		1716	might be be delayed. One such system is the Linux kernel, where a call to
		1717	C<gettimeofday> might return a timestamp with a full second later than
		1718	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1719	update file times then there will be a small window where the kernel uses
		1720	the previous second to update file times but libev might already execute
		1721	the timer callback).
1637		1722
1638	=head3 Watcher-Specific Functions and Data Members	1723	=head3 Watcher-Specific Functions and Data Members
1639		1724
1640	=over 4	1725	=over 4
1641		1726
…		…
1647	C<path>. The C<interval> is a hint on how quickly a change is expected to	1732	C<path>. The C<interval> is a hint on how quickly a change is expected to
1648	be detected and should normally be specified as C<0> to let libev choose	1733	be detected and should normally be specified as C<0> to let libev choose
1649	a suitable value. The memory pointed to by C<path> must point to the same	1734	a suitable value. The memory pointed to by C<path> must point to the same
1650	path for as long as the watcher is active.	1735	path for as long as the watcher is active.
1651		1736
1652	The callback will be receive C<EV_STAT> when a change was detected,	1737	The callback will receive C<EV_STAT> when a change was detected, relative
1653	relative to the attributes at the time the watcher was started (or the	1738	to the attributes at the time the watcher was started (or the last change
1654	last change was detected).	1739	was detected).
1655		1740
1656	=item ev_stat_stat (loop, ev_stat *)	1741	=item ev_stat_stat (loop, ev_stat *)
1657		1742
1658	Updates the stat buffer immediately with new values. If you change the	1743	Updates the stat buffer immediately with new values. If you change the
1659	watched path in your callback, you could call this fucntion to avoid	1744	watched path in your callback, you could call this function to avoid
1660	detecting this change (while introducing a race condition). Can also be	1745	detecting this change (while introducing a race condition if you are not
1661	useful simply to find out the new values.	1746	the only one changing the path). Can also be useful simply to find out the
		1747	new values.
1662		1748
1663	=item ev_statdata attr [read-only]	1749	=item ev_statdata attr [read-only]
1664		1750
1665	The most-recently detected attributes of the file. Although the type is of	1751	The most-recently detected attributes of the file. Although the type is
1666	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types	1752	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
1667	suitable for your system. If the C<st_nlink> member is C<0>, then there	1753	suitable for your system, but you can only rely on the POSIX-standardised
		1754	members to be present. If the C<st_nlink> member is C<0>, then there was
1668	was some error while C<stat>ing the file.	1755	some error while C<stat>ing the file.
1669		1756
1670	=item ev_statdata prev [read-only]	1757	=item ev_statdata prev [read-only]
1671		1758
1672	The previous attributes of the file. The callback gets invoked whenever	1759	The previous attributes of the file. The callback gets invoked whenever
1673	C<prev> != C<attr>.	1760	C<prev> != C<attr>, or, more precisely, one or more of these members
		1761	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1762	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1674		1763
1675	=item ev_tstamp interval [read-only]	1764	=item ev_tstamp interval [read-only]
1676		1765
1677	The specified interval.	1766	The specified interval.
1678		1767
1679	=item const char *path [read-only]	1768	=item const char *path [read-only]
1680		1769
1681	The filesystem path that is being watched.	1770	The file system path that is being watched.
1682		1771
1683	=back	1772	=back
1684		1773
1685	=head3 Examples	1774	=head3 Examples
1686		1775
1687	Example: Watch C</etc/passwd> for attribute changes.	1776	Example: Watch C</etc/passwd> for attribute changes.
1688		1777
1689	static void	1778	static void
1690	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1779	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1691	{	1780	{
1692	/* /etc/passwd changed in some way */	1781	/* /etc/passwd changed in some way */
1693	if (w->attr.st_nlink)	1782	if (w->attr.st_nlink)
1694	{	1783	{
1695	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1784	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1696	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1785	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1697	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1786	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1698	}	1787	}
1699	else	1788	else
1700	/* you shalt not abuse printf for puts */	1789	/* you shalt not abuse printf for puts */
1701	puts ("wow, /etc/passwd is not there, expect problems. "	1790	puts ("wow, /etc/passwd is not there, expect problems. "
1702	"if this is windows, they already arrived\n");	1791	"if this is windows, they already arrived\n");
1703	}	1792	}
1704		1793
1705	...	1794	...
1706	ev_stat passwd;	1795	ev_stat passwd;
1707		1796
1708	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1797	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1709	ev_stat_start (loop, &passwd);	1798	ev_stat_start (loop, &passwd);
1710		1799
1711	Example: Like above, but additionally use a one-second delay so we do not	1800	Example: Like above, but additionally use a one-second delay so we do not
1712	miss updates (however, frequent updates will delay processing, too, so	1801	miss updates (however, frequent updates will delay processing, too, so
1713	one might do the work both on C<ev_stat> callback invocation I<and> on	1802	one might do the work both on C<ev_stat> callback invocation I<and> on
1714	C<ev_timer> callback invocation).	1803	C<ev_timer> callback invocation).
1715		1804
1716	static ev_stat passwd;	1805	static ev_stat passwd;
1717	static ev_timer timer;	1806	static ev_timer timer;
1718		1807
1719	static void	1808	static void
1720	timer_cb (EV_P_ ev_timer *w, int revents)	1809	timer_cb (EV_P_ ev_timer *w, int revents)
1721	{	1810	{
1722	ev_timer_stop (EV_A_ w);	1811	ev_timer_stop (EV_A_ w);
1723		1812
1724	/* now it's one second after the most recent passwd change */	1813	/* now it's one second after the most recent passwd change */
1725	}	1814	}
1726		1815
1727	static void	1816	static void
1728	stat_cb (EV_P_ ev_stat *w, int revents)	1817	stat_cb (EV_P_ ev_stat *w, int revents)
1729	{	1818	{
1730	/* reset the one-second timer */	1819	/* reset the one-second timer */
1731	ev_timer_again (EV_A_ &timer);	1820	ev_timer_again (EV_A_ &timer);
1732	}	1821	}
1733		1822
1734	...	1823	...
1735	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1824	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1736	ev_stat_start (loop, &passwd);	1825	ev_stat_start (loop, &passwd);
1737	ev_timer_init (&timer, timer_cb, 0., 1.01);	1826	ev_timer_init (&timer, timer_cb, 0., 1.02);
1738		1827
1739		1828
1740	=head2 C<ev_idle> - when you've got nothing better to do...	1829	=head2 C<ev_idle> - when you've got nothing better to do...
1741		1830
1742	Idle watchers trigger events when no other events of the same or higher	1831	Idle watchers trigger events when no other events of the same or higher
…		…
1773	=head3 Examples	1862	=head3 Examples
1774		1863
1775	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1864	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1776	callback, free it. Also, use no error checking, as usual.	1865	callback, free it. Also, use no error checking, as usual.
1777		1866
1778	static void	1867	static void
1779	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1868	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1780	{	1869	{
1781	free (w);	1870	free (w);
1782	// now do something you wanted to do when the program has	1871	// now do something you wanted to do when the program has
1783	// no longer anything immediate to do.	1872	// no longer anything immediate to do.
1784	}	1873	}
1785		1874
1786	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1875	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1787	ev_idle_init (idle_watcher, idle_cb);	1876	ev_idle_init (idle_watcher, idle_cb);
1788	ev_idle_start (loop, idle_cb);	1877	ev_idle_start (loop, idle_cb);
1789		1878
1790		1879
1791	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1880	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1792		1881
1793	Prepare and check watchers are usually (but not always) used in tandem:	1882	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1812		1901
1813	This is done by examining in each prepare call which file descriptors need	1902	This is done by examining in each prepare call which file descriptors need
1814	to be watched by the other library, registering C<ev_io> watchers for	1903	to be watched by the other library, registering C<ev_io> watchers for
1815	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1904	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1816	provide just this functionality). Then, in the check watcher you check for	1905	provide just this functionality). Then, in the check watcher you check for
1817	any events that occured (by checking the pending status of all watchers	1906	any events that occurred (by checking the pending status of all watchers
1818	and stopping them) and call back into the library. The I/O and timer	1907	and stopping them) and call back into the library. The I/O and timer
1819	callbacks will never actually be called (but must be valid nevertheless,	1908	callbacks will never actually be called (but must be valid nevertheless,
1820	because you never know, you know?).	1909	because you never know, you know?).
1821		1910
1822	As another example, the Perl Coro module uses these hooks to integrate	1911	As another example, the Perl Coro module uses these hooks to integrate
…		…
1830		1919
1831	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1920	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
1832	priority, to ensure that they are being run before any other watchers	1921	priority, to ensure that they are being run before any other watchers
1833	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,	1922	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
1834	too) should not activate ("feed") events into libev. While libev fully	1923	too) should not activate ("feed") events into libev. While libev fully
1835	supports this, they will be called before other C<ev_check> watchers	1924	supports this, they might get executed before other C<ev_check> watchers
1836	did their job. As C<ev_check> watchers are often used to embed other	1925	did their job. As C<ev_check> watchers are often used to embed other
1837	(non-libev) event loops those other event loops might be in an unusable	1926	(non-libev) event loops those other event loops might be in an unusable
1838	state until their C<ev_check> watcher ran (always remind yourself to	1927	state until their C<ev_check> watcher ran (always remind yourself to
1839	coexist peacefully with others).	1928	coexist peacefully with others).
1840		1929
…		…
1855	=head3 Examples	1944	=head3 Examples
1856		1945
1857	There are a number of principal ways to embed other event loops or modules	1946	There are a number of principal ways to embed other event loops or modules
1858	into libev. Here are some ideas on how to include libadns into libev	1947	into libev. Here are some ideas on how to include libadns into libev
1859	(there is a Perl module named C<EV::ADNS> that does this, which you could	1948	(there is a Perl module named C<EV::ADNS> that does this, which you could
1860	use for an actually working example. Another Perl module named C<EV::Glib>	1949	use as a working example. Another Perl module named C<EV::Glib> embeds a
1861	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV	1950	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1862	into the Glib event loop).	1951	Glib event loop).
1863		1952
1864	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	1953	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1865	and in a check watcher, destroy them and call into libadns. What follows	1954	and in a check watcher, destroy them and call into libadns. What follows
1866	is pseudo-code only of course. This requires you to either use a low	1955	is pseudo-code only of course. This requires you to either use a low
1867	priority for the check watcher or use C<ev_clear_pending> explicitly, as	1956	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1868	the callbacks for the IO/timeout watchers might not have been called yet.	1957	the callbacks for the IO/timeout watchers might not have been called yet.
1869		1958
1870	static ev_io iow [nfd];	1959	static ev_io iow [nfd];
1871	static ev_timer tw;	1960	static ev_timer tw;
1872		1961
1873	static void	1962	static void
1874	io_cb (ev_loop *loop, ev_io *w, int revents)	1963	io_cb (ev_loop *loop, ev_io *w, int revents)
1875	{	1964	{
1876	}	1965	}
1877		1966
1878	// create io watchers for each fd and a timer before blocking	1967	// create io watchers for each fd and a timer before blocking
1879	static void	1968	static void
1880	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1969	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1881	{	1970	{
1882	int timeout = 3600000;	1971	int timeout = 3600000;
1883	struct pollfd fds [nfd];	1972	struct pollfd fds [nfd];
1884	// actual code will need to loop here and realloc etc.	1973	// actual code will need to loop here and realloc etc.
1885	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1974	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1886		1975
1887	/* the callback is illegal, but won't be called as we stop during check */	1976	/* the callback is illegal, but won't be called as we stop during check */
1888	ev_timer_init (&tw, 0, timeout * 1e-3);	1977	ev_timer_init (&tw, 0, timeout * 1e-3);
1889	ev_timer_start (loop, &tw);	1978	ev_timer_start (loop, &tw);
1890		1979
1891	// create one ev_io per pollfd	1980	// create one ev_io per pollfd
1892	for (int i = 0; i < nfd; ++i)	1981	for (int i = 0; i < nfd; ++i)
1893	{	1982	{
1894	ev_io_init (iow + i, io_cb, fds [i].fd,	1983	ev_io_init (iow + i, io_cb, fds [i].fd,
1895	((fds [i].events & POLLIN ? EV_READ : 0)	1984	((fds [i].events & POLLIN ? EV_READ : 0)
1896	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1985	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1897		1986
1898	fds [i].revents = 0;	1987	fds [i].revents = 0;
1899	ev_io_start (loop, iow + i);	1988	ev_io_start (loop, iow + i);
1900	}	1989	}
1901	}	1990	}
1902		1991
1903	// stop all watchers after blocking	1992	// stop all watchers after blocking
1904	static void	1993	static void
1905	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1994	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1906	{	1995	{
1907	ev_timer_stop (loop, &tw);	1996	ev_timer_stop (loop, &tw);
1908		1997
1909	for (int i = 0; i < nfd; ++i)	1998	for (int i = 0; i < nfd; ++i)
1910	{	1999	{
1911	// set the relevant poll flags	2000	// set the relevant poll flags
1912	// could also call adns_processreadable etc. here	2001	// could also call adns_processreadable etc. here
1913	struct pollfd *fd = fds + i;	2002	struct pollfd *fd = fds + i;
1914	int revents = ev_clear_pending (iow + i);	2003	int revents = ev_clear_pending (iow + i);
1915	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	2004	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1916	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	2005	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1917		2006
1918	// now stop the watcher	2007	// now stop the watcher
1919	ev_io_stop (loop, iow + i);	2008	ev_io_stop (loop, iow + i);
1920	}	2009	}
1921		2010
1922	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2011	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1923	}	2012	}
1924		2013
1925	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2014	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
1926	in the prepare watcher and would dispose of the check watcher.	2015	in the prepare watcher and would dispose of the check watcher.
1927		2016
1928	Method 3: If the module to be embedded supports explicit event	2017	Method 3: If the module to be embedded supports explicit event
1929	notification (adns does), you can also make use of the actual watcher	2018	notification (libadns does), you can also make use of the actual watcher
1930	callbacks, and only destroy/create the watchers in the prepare watcher.	2019	callbacks, and only destroy/create the watchers in the prepare watcher.
1931		2020
1932	static void	2021	static void
1933	timer_cb (EV_P_ ev_timer *w, int revents)	2022	timer_cb (EV_P_ ev_timer *w, int revents)
1934	{	2023	{
1935	adns_state ads = (adns_state)w->data;	2024	adns_state ads = (adns_state)w->data;
1936	update_now (EV_A);	2025	update_now (EV_A);
1937		2026
1938	adns_processtimeouts (ads, &tv_now);	2027	adns_processtimeouts (ads, &tv_now);
1939	}	2028	}
1940		2029
1941	static void	2030	static void
1942	io_cb (EV_P_ ev_io *w, int revents)	2031	io_cb (EV_P_ ev_io *w, int revents)
1943	{	2032	{
1944	adns_state ads = (adns_state)w->data;	2033	adns_state ads = (adns_state)w->data;
1945	update_now (EV_A);	2034	update_now (EV_A);
1946		2035
1947	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2036	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1948	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2037	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1949	}	2038	}
1950		2039
1951	// do not ever call adns_afterpoll	2040	// do not ever call adns_afterpoll
1952		2041
1953	Method 4: Do not use a prepare or check watcher because the module you	2042	Method 4: Do not use a prepare or check watcher because the module you
1954	want to embed is too inflexible to support it. Instead, youc na override	2043	want to embed is too inflexible to support it. Instead, you can override
1955	their poll function. The drawback with this solution is that the main	2044	their poll function. The drawback with this solution is that the main
1956	loop is now no longer controllable by EV. The C<Glib::EV> module does	2045	loop is now no longer controllable by EV. The C<Glib::EV> module does
1957	this.	2046	this.
1958		2047
1959	static gint	2048	static gint
1960	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2049	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1961	{	2050	{
1962	int got_events = 0;	2051	int got_events = 0;
1963		2052
1964	for (n = 0; n < nfds; ++n)	2053	for (n = 0; n < nfds; ++n)
1965	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2054	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1966		2055
1967	if (timeout >= 0)	2056	if (timeout >= 0)
1968	// create/start timer	2057	// create/start timer
1969		2058
1970	// poll	2059	// poll
1971	ev_loop (EV_A_ 0);	2060	ev_loop (EV_A_ 0);
1972		2061
1973	// stop timer again	2062	// stop timer again
1974	if (timeout >= 0)	2063	if (timeout >= 0)
1975	ev_timer_stop (EV_A_ &to);	2064	ev_timer_stop (EV_A_ &to);
1976		2065
1977	// stop io watchers again - their callbacks should have set	2066	// stop io watchers again - their callbacks should have set
1978	for (n = 0; n < nfds; ++n)	2067	for (n = 0; n < nfds; ++n)
1979	ev_io_stop (EV_A_ iow [n]);	2068	ev_io_stop (EV_A_ iow [n]);
1980		2069
1981	return got_events;	2070	return got_events;
1982	}	2071	}
1983		2072
1984		2073
1985	=head2 C<ev_embed> - when one backend isn't enough...	2074	=head2 C<ev_embed> - when one backend isn't enough...
1986		2075
1987	This is a rather advanced watcher type that lets you embed one event loop	2076	This is a rather advanced watcher type that lets you embed one event loop
…		…
2043		2132
2044	Configures the watcher to embed the given loop, which must be	2133	Configures the watcher to embed the given loop, which must be
2045	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be	2134	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
2046	invoked automatically, otherwise it is the responsibility of the callback	2135	invoked automatically, otherwise it is the responsibility of the callback
2047	to invoke it (it will continue to be called until the sweep has been done,	2136	to invoke it (it will continue to be called until the sweep has been done,
2048	if you do not want thta, you need to temporarily stop the embed watcher).	2137	if you do not want that, you need to temporarily stop the embed watcher).
2049		2138
2050	=item ev_embed_sweep (loop, ev_embed *)	2139	=item ev_embed_sweep (loop, ev_embed *)
2051		2140
2052	Make a single, non-blocking sweep over the embedded loop. This works	2141	Make a single, non-blocking sweep over the embedded loop. This works
2053	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2142	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2054	apropriate way for embedded loops.	2143	appropriate way for embedded loops.
2055		2144
2056	=item struct ev_loop *other [read-only]	2145	=item struct ev_loop *other [read-only]
2057		2146
2058	The embedded event loop.	2147	The embedded event loop.
2059		2148
…		…
2061		2150
2062	=head3 Examples	2151	=head3 Examples
2063		2152
2064	Example: Try to get an embeddable event loop and embed it into the default	2153	Example: Try to get an embeddable event loop and embed it into the default
2065	event loop. If that is not possible, use the default loop. The default	2154	event loop. If that is not possible, use the default loop. The default
2066	loop is stored in C<loop_hi>, while the mebeddable loop is stored in	2155	loop is stored in C<loop_hi>, while the embeddable loop is stored in
2067	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be	2156	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2068	used).	2157	used).
2069		2158
2070	struct ev_loop *loop_hi = ev_default_init (0);	2159	struct ev_loop *loop_hi = ev_default_init (0);
2071	struct ev_loop *loop_lo = 0;	2160	struct ev_loop *loop_lo = 0;
2072	struct ev_embed embed;	2161	struct ev_embed embed;
2073		2162
2074	// see if there is a chance of getting one that works	2163	// see if there is a chance of getting one that works
2075	// (remember that a flags value of 0 means autodetection)	2164	// (remember that a flags value of 0 means autodetection)
2076	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2165	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2077	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2166	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2078	: 0;	2167	: 0;
2079		2168
2080	// if we got one, then embed it, otherwise default to loop_hi	2169	// if we got one, then embed it, otherwise default to loop_hi
2081	if (loop_lo)	2170	if (loop_lo)
2082	{	2171	{
2083	ev_embed_init (&embed, 0, loop_lo);	2172	ev_embed_init (&embed, 0, loop_lo);
2084	ev_embed_start (loop_hi, &embed);	2173	ev_embed_start (loop_hi, &embed);
2085	}	2174	}
2086	else	2175	else
2087	loop_lo = loop_hi;	2176	loop_lo = loop_hi;
2088		2177
2089	Example: Check if kqueue is available but not recommended and create	2178	Example: Check if kqueue is available but not recommended and create
2090	a kqueue backend for use with sockets (which usually work with any	2179	a kqueue backend for use with sockets (which usually work with any
2091	kqueue implementation). Store the kqueue/socket-only event loop in	2180	kqueue implementation). Store the kqueue/socket-only event loop in
2092	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2181	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2093		2182
2094	struct ev_loop *loop = ev_default_init (0);	2183	struct ev_loop *loop = ev_default_init (0);
2095	struct ev_loop *loop_socket = 0;	2184	struct ev_loop *loop_socket = 0;
2096	struct ev_embed embed;	2185	struct ev_embed embed;
2097		2186
2098	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2187	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2099	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2188	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2100	{	2189	{
2101	ev_embed_init (&embed, 0, loop_socket);	2190	ev_embed_init (&embed, 0, loop_socket);
2102	ev_embed_start (loop, &embed);	2191	ev_embed_start (loop, &embed);
2103	}	2192	}
2104		2193
2105	if (!loop_socket)	2194	if (!loop_socket)
2106	loop_socket = loop;	2195	loop_socket = loop;
2107		2196
2108	// now use loop_socket for all sockets, and loop for everything else	2197	// now use loop_socket for all sockets, and loop for everything else
2109		2198
2110		2199
2111	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2200	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2112		2201
2113	Fork watchers are called when a C<fork ()> was detected (usually because	2202	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2166		2255
2167	=item queueing from a signal handler context	2256	=item queueing from a signal handler context
2168		2257
2169	To implement race-free queueing, you simply add to the queue in the signal	2258	To implement race-free queueing, you simply add to the queue in the signal
2170	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2259	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2171	some fictitiuous SIGUSR1 handler:	2260	some fictitious SIGUSR1 handler:
2172		2261
2173	static ev_async mysig;	2262	static ev_async mysig;
2174		2263
2175	static void	2264	static void
2176	sigusr1_handler (void)	2265	sigusr1_handler (void)
…		…
2250	=item ev_async_send (loop, ev_async *)	2339	=item ev_async_send (loop, ev_async *)
2251		2340
2252	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2341	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2253	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2342	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2254	C<ev_feed_event>, this call is safe to do in other threads, signal or	2343	C<ev_feed_event>, this call is safe to do in other threads, signal or
2255	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding	2344	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2256	section below on what exactly this means).	2345	section below on what exactly this means).
2257		2346
2258	This call incurs the overhead of a syscall only once per loop iteration,	2347	This call incurs the overhead of a system call only once per loop iteration,
2259	so while the overhead might be noticable, it doesn't apply to repeated	2348	so while the overhead might be noticeable, it doesn't apply to repeated
2260	calls to C<ev_async_send>.	2349	calls to C<ev_async_send>.
		2350
		2351	=item bool = ev_async_pending (ev_async *)
		2352
		2353	Returns a non-zero value when C<ev_async_send> has been called on the
		2354	watcher but the event has not yet been processed (or even noted) by the
		2355	event loop.
		2356
		2357	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
		2358	the loop iterates next and checks for the watcher to have become active,
		2359	it will reset the flag again. C<ev_async_pending> can be used to very
		2360	quickly check whether invoking the loop might be a good idea.
		2361
		2362	Not that this does I<not> check whether the watcher itself is pending, only
		2363	whether it has been requested to make this watcher pending.
2261		2364
2262	=back	2365	=back
2263		2366
2264		2367
2265	=head1 OTHER FUNCTIONS	2368	=head1 OTHER FUNCTIONS
…		…
2276	or timeout without having to allocate/configure/start/stop/free one or	2379	or timeout without having to allocate/configure/start/stop/free one or
2277	more watchers yourself.	2380	more watchers yourself.
2278		2381
2279	If C<fd> is less than 0, then no I/O watcher will be started and events	2382	If C<fd> is less than 0, then no I/O watcher will be started and events
2280	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2383	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2281	C<events> set will be craeted and started.	2384	C<events> set will be created and started.
2282		2385
2283	If C<timeout> is less than 0, then no timeout watcher will be	2386	If C<timeout> is less than 0, then no timeout watcher will be
2284	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2387	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2285	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2388	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2286	dubious value.	2389	dubious value.
…		…
2288	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2391	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2289	passed an C<revents> set like normal event callbacks (a combination of	2392	passed an C<revents> set like normal event callbacks (a combination of
2290	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2393	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2291	value passed to C<ev_once>:	2394	value passed to C<ev_once>:
2292		2395
2293	static void stdin_ready (int revents, void *arg)	2396	static void stdin_ready (int revents, void *arg)
2294	{	2397	{
2295	if (revents & EV_TIMEOUT)	2398	if (revents & EV_TIMEOUT)
2296	/* doh, nothing entered */;	2399	/* doh, nothing entered */;
2297	else if (revents & EV_READ)	2400	else if (revents & EV_READ)
2298	/* stdin might have data for us, joy! */;	2401	/* stdin might have data for us, joy! */;
2299	}	2402	}
2300		2403
2301	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2404	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2302		2405
2303	=item ev_feed_event (ev_loop *, watcher *, int revents)	2406	=item ev_feed_event (ev_loop *, watcher *, int revents)
2304		2407
2305	Feeds the given event set into the event loop, as if the specified event	2408	Feeds the given event set into the event loop, as if the specified event
2306	had happened for the specified watcher (which must be a pointer to an	2409	had happened for the specified watcher (which must be a pointer to an
…		…
2311	Feed an event on the given fd, as if a file descriptor backend detected	2414	Feed an event on the given fd, as if a file descriptor backend detected
2312	the given events it.	2415	the given events it.
2313		2416
2314	=item ev_feed_signal_event (ev_loop *loop, int signum)	2417	=item ev_feed_signal_event (ev_loop *loop, int signum)
2315		2418
2316	Feed an event as if the given signal occured (C<loop> must be the default	2419	Feed an event as if the given signal occurred (C<loop> must be the default
2317	loop!).	2420	loop!).
2318		2421
2319	=back	2422	=back
2320		2423
2321		2424
…		…
2337		2440
2338	=item * Priorities are not currently supported. Initialising priorities	2441	=item * Priorities are not currently supported. Initialising priorities
2339	will fail and all watchers will have the same priority, even though there	2442	will fail and all watchers will have the same priority, even though there
2340	is an ev_pri field.	2443	is an ev_pri field.
2341		2444
		2445	=item * In libevent, the last base created gets the signals, in libev, the
		2446	first base created (== the default loop) gets the signals.
		2447
2342	=item * Other members are not supported.	2448	=item * Other members are not supported.
2343		2449
2344	=item * The libev emulation is I<not> ABI compatible to libevent, you need	2450	=item * The libev emulation is I<not> ABI compatible to libevent, you need
2345	to use the libev header file and library.	2451	to use the libev header file and library.
2346		2452
2347	=back	2453	=back
2348		2454
2349	=head1 C++ SUPPORT	2455	=head1 C++ SUPPORT
2350		2456
2351	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2457	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2352	you to use some convinience methods to start/stop watchers and also change	2458	you to use some convenience methods to start/stop watchers and also change
2353	the callback model to a model using method callbacks on objects.	2459	the callback model to a model using method callbacks on objects.
2354		2460
2355	To use it,	2461	To use it,
2356		2462
2357	#include <ev++.h>	2463	#include <ev++.h>
2358		2464
2359	This automatically includes F<ev.h> and puts all of its definitions (many	2465	This automatically includes F<ev.h> and puts all of its definitions (many
2360	of them macros) into the global namespace. All C++ specific things are	2466	of them macros) into the global namespace. All C++ specific things are
2361	put into the C<ev> namespace. It should support all the same embedding	2467	put into the C<ev> namespace. It should support all the same embedding
2362	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2468	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2429	your compiler is good :), then the method will be fully inlined into the	2535	your compiler is good :), then the method will be fully inlined into the
2430	thunking function, making it as fast as a direct C callback.	2536	thunking function, making it as fast as a direct C callback.
2431		2537
2432	Example: simple class declaration and watcher initialisation	2538	Example: simple class declaration and watcher initialisation
2433		2539
2434	struct myclass	2540	struct myclass
2435	{	2541	{
2436	void io_cb (ev::io &w, int revents) { }	2542	void io_cb (ev::io &w, int revents) { }
2437	}	2543	}
2438		2544
2439	myclass obj;	2545	myclass obj;
2440	ev::io iow;	2546	ev::io iow;
2441	iow.set <myclass, &myclass::io_cb> (&obj);	2547	iow.set <myclass, &myclass::io_cb> (&obj);
2442		2548
2443	=item w->set<function> (void *data = 0)	2549	=item w->set<function> (void *data = 0)
2444		2550
2445	Also sets a callback, but uses a static method or plain function as	2551	Also sets a callback, but uses a static method or plain function as
2446	callback. The optional C<data> argument will be stored in the watcher's	2552	callback. The optional C<data> argument will be stored in the watcher's
…		…
2450		2556
2451	See the method-C<set> above for more details.	2557	See the method-C<set> above for more details.
2452		2558
2453	Example:	2559	Example:
2454		2560
2455	static void io_cb (ev::io &w, int revents) { }	2561	static void io_cb (ev::io &w, int revents) { }
2456	iow.set <io_cb> ();	2562	iow.set <io_cb> ();
2457		2563
2458	=item w->set (struct ev_loop *)	2564	=item w->set (struct ev_loop *)
2459		2565
2460	Associates a different C<struct ev_loop> with this watcher. You can only	2566	Associates a different C<struct ev_loop> with this watcher. You can only
2461	do this when the watcher is inactive (and not pending either).	2567	do this when the watcher is inactive (and not pending either).
2462		2568
2463	=item w->set ([args])	2569	=item w->set ([arguments])
2464		2570
2465	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2571	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2466	called at least once. Unlike the C counterpart, an active watcher gets	2572	called at least once. Unlike the C counterpart, an active watcher gets
2467	automatically stopped and restarted when reconfiguring it with this	2573	automatically stopped and restarted when reconfiguring it with this
2468	method.	2574	method.
2469		2575
2470	=item w->start ()	2576	=item w->start ()
…		…
2494	=back	2600	=back
2495		2601
2496	Example: Define a class with an IO and idle watcher, start one of them in	2602	Example: Define a class with an IO and idle watcher, start one of them in
2497	the constructor.	2603	the constructor.
2498		2604
2499	class myclass	2605	class myclass
2500	{	2606	{
2501	ev::io io; void io_cb (ev::io &w, int revents);	2607	ev::io io; void io_cb (ev::io &w, int revents);
2502	ev:idle idle void idle_cb (ev::idle &w, int revents);	2608	ev:idle idle void idle_cb (ev::idle &w, int revents);
2503		2609
2504	myclass (int fd)	2610	myclass (int fd)
2505	{	2611	{
2506	io .set <myclass, &myclass::io_cb > (this);	2612	io .set <myclass, &myclass::io_cb > (this);
2507	idle.set <myclass, &myclass::idle_cb> (this);	2613	idle.set <myclass, &myclass::idle_cb> (this);
2508		2614
2509	io.start (fd, ev::READ);	2615	io.start (fd, ev::READ);
2510	}	2616	}
2511	};	2617	};
2512		2618
2513		2619
2514	=head1 OTHER LANGUAGE BINDINGS	2620	=head1 OTHER LANGUAGE BINDINGS
2515		2621
2516	Libev does not offer other language bindings itself, but bindings for a	2622	Libev does not offer other language bindings itself, but bindings for a
2517	numbe rof languages exist in the form of third-party packages. If you know	2623	number of languages exist in the form of third-party packages. If you know
2518	any interesting language binding in addition to the ones listed here, drop	2624	any interesting language binding in addition to the ones listed here, drop
2519	me a note.	2625	me a note.
2520		2626
2521	=over 4	2627	=over 4
2522		2628
…		…
2526	libev. EV is developed together with libev. Apart from the EV core module,	2632	libev. EV is developed together with libev. Apart from the EV core module,
2527	there are additional modules that implement libev-compatible interfaces	2633	there are additional modules that implement libev-compatible interfaces
2528	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the	2634	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
2529	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).	2635	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2530		2636
2531	It can be found and installed via CPAN, its homepage is found at	2637	It can be found and installed via CPAN, its homepage is at
2532	L<http://software.schmorp.de/pkg/EV>.	2638	L<http://software.schmorp.de/pkg/EV>.
2533		2639
		2640	=item Python
		2641
		2642	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2643	seems to be quite complete and well-documented. Note, however, that the
		2644	patch they require for libev is outright dangerous as it breaks the ABI
		2645	for everybody else, and therefore, should never be applied in an installed
		2646	libev (if python requires an incompatible ABI then it needs to embed
		2647	libev).
		2648
2534	=item Ruby	2649	=item Ruby
2535		2650
2536	Tony Arcieri has written a ruby extension that offers access to a subset	2651	Tony Arcieri has written a ruby extension that offers access to a subset
2537	of the libev API and adds filehandle abstractions, asynchronous DNS and	2652	of the libev API and adds file handle abstractions, asynchronous DNS and
2538	more on top of it. It can be found via gem servers. Its homepage is at	2653	more on top of it. It can be found via gem servers. Its homepage is at
2539	L<http://rev.rubyforge.org/>.	2654	L<http://rev.rubyforge.org/>.
2540		2655
2541	=item D	2656	=item D
2542		2657
…		…
2546	=back	2661	=back
2547		2662
2548		2663
2549	=head1 MACRO MAGIC	2664	=head1 MACRO MAGIC
2550		2665
2551	Libev can be compiled with a variety of options, the most fundamantal	2666	Libev can be compiled with a variety of options, the most fundamental
2552	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2667	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2553	functions and callbacks have an initial C<struct ev_loop *> argument.	2668	functions and callbacks have an initial C<struct ev_loop *> argument.
2554		2669
2555	To make it easier to write programs that cope with either variant, the	2670	To make it easier to write programs that cope with either variant, the
2556	following macros are defined:	2671	following macros are defined:
…		…
2561		2676
2562	This provides the loop I<argument> for functions, if one is required ("ev	2677	This provides the loop I<argument> for functions, if one is required ("ev
2563	loop argument"). The C<EV_A> form is used when this is the sole argument,	2678	loop argument"). The C<EV_A> form is used when this is the sole argument,
2564	C<EV_A_> is used when other arguments are following. Example:	2679	C<EV_A_> is used when other arguments are following. Example:
2565		2680
2566	ev_unref (EV_A);	2681	ev_unref (EV_A);
2567	ev_timer_add (EV_A_ watcher);	2682	ev_timer_add (EV_A_ watcher);
2568	ev_loop (EV_A_ 0);	2683	ev_loop (EV_A_ 0);
2569		2684
2570	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2685	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2571	which is often provided by the following macro.	2686	which is often provided by the following macro.
2572		2687
2573	=item C<EV_P>, C<EV_P_>	2688	=item C<EV_P>, C<EV_P_>
2574		2689
2575	This provides the loop I<parameter> for functions, if one is required ("ev	2690	This provides the loop I<parameter> for functions, if one is required ("ev
2576	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2691	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2577	C<EV_P_> is used when other parameters are following. Example:	2692	C<EV_P_> is used when other parameters are following. Example:
2578		2693
2579	// this is how ev_unref is being declared	2694	// this is how ev_unref is being declared
2580	static void ev_unref (EV_P);	2695	static void ev_unref (EV_P);
2581		2696
2582	// this is how you can declare your typical callback	2697	// this is how you can declare your typical callback
2583	static void cb (EV_P_ ev_timer *w, int revents)	2698	static void cb (EV_P_ ev_timer *w, int revents)
2584		2699
2585	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2700	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2586	suitable for use with C<EV_A>.	2701	suitable for use with C<EV_A>.
2587		2702
2588	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2703	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
2589		2704
2590	Similar to the other two macros, this gives you the value of the default	2705	Similar to the other two macros, this gives you the value of the default
2591	loop, if multiple loops are supported ("ev loop default").	2706	loop, if multiple loops are supported ("ev loop default").
		2707
		2708	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
		2709
		2710	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
		2711	default loop has been initialised (C<UC> == unchecked). Their behaviour
		2712	is undefined when the default loop has not been initialised by a previous
		2713	execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
		2714
		2715	It is often prudent to use C<EV_DEFAULT> when initialising the first
		2716	watcher in a function but use C<EV_DEFAULT_UC> afterwards.
2592		2717
2593	=back	2718	=back
2594		2719
2595	Example: Declare and initialise a check watcher, utilising the above	2720	Example: Declare and initialise a check watcher, utilising the above
2596	macros so it will work regardless of whether multiple loops are supported	2721	macros so it will work regardless of whether multiple loops are supported
2597	or not.	2722	or not.
2598		2723
2599	static void	2724	static void
2600	check_cb (EV_P_ ev_timer *w, int revents)	2725	check_cb (EV_P_ ev_timer *w, int revents)
2601	{	2726	{
2602	ev_check_stop (EV_A_ w);	2727	ev_check_stop (EV_A_ w);
2603	}	2728	}
2604		2729
2605	ev_check check;	2730	ev_check check;
2606	ev_check_init (&check, check_cb);	2731	ev_check_init (&check, check_cb);
2607	ev_check_start (EV_DEFAULT_ &check);	2732	ev_check_start (EV_DEFAULT_ &check);
2608	ev_loop (EV_DEFAULT_ 0);	2733	ev_loop (EV_DEFAULT_ 0);
2609		2734
2610	=head1 EMBEDDING	2735	=head1 EMBEDDING
2611		2736
2612	Libev can (and often is) directly embedded into host	2737	Libev can (and often is) directly embedded into host
2613	applications. Examples of applications that embed it include the Deliantra	2738	applications. Examples of applications that embed it include the Deliantra
…		…
2620	libev somewhere in your source tree).	2745	libev somewhere in your source tree).
2621		2746
2622	=head2 FILESETS	2747	=head2 FILESETS
2623		2748
2624	Depending on what features you need you need to include one or more sets of files	2749	Depending on what features you need you need to include one or more sets of files
2625	in your app.	2750	in your application.
2626		2751
2627	=head3 CORE EVENT LOOP	2752	=head3 CORE EVENT LOOP
2628		2753
2629	To include only the libev core (all the C<ev_*> functions), with manual	2754	To include only the libev core (all the C<ev_*> functions), with manual
2630	configuration (no autoconf):	2755	configuration (no autoconf):
2631		2756
2632	#define EV_STANDALONE 1	2757	#define EV_STANDALONE 1
2633	#include "ev.c"	2758	#include "ev.c"
2634		2759
2635	This will automatically include F<ev.h>, too, and should be done in a	2760	This will automatically include F<ev.h>, too, and should be done in a
2636	single C source file only to provide the function implementations. To use	2761	single C source file only to provide the function implementations. To use
2637	it, do the same for F<ev.h> in all files wishing to use this API (best	2762	it, do the same for F<ev.h> in all files wishing to use this API (best
2638	done by writing a wrapper around F<ev.h> that you can include instead and	2763	done by writing a wrapper around F<ev.h> that you can include instead and
2639	where you can put other configuration options):	2764	where you can put other configuration options):
2640		2765
2641	#define EV_STANDALONE 1	2766	#define EV_STANDALONE 1
2642	#include "ev.h"	2767	#include "ev.h"
2643		2768
2644	Both header files and implementation files can be compiled with a C++	2769	Both header files and implementation files can be compiled with a C++
2645	compiler (at least, thats a stated goal, and breakage will be treated	2770	compiler (at least, thats a stated goal, and breakage will be treated
2646	as a bug).	2771	as a bug).
2647		2772
2648	You need the following files in your source tree, or in a directory	2773	You need the following files in your source tree, or in a directory
2649	in your include path (e.g. in libev/ when using -Ilibev):	2774	in your include path (e.g. in libev/ when using -Ilibev):
2650		2775
2651	ev.h	2776	ev.h
2652	ev.c	2777	ev.c
2653	ev_vars.h	2778	ev_vars.h
2654	ev_wrap.h	2779	ev_wrap.h
2655		2780
2656	ev_win32.c required on win32 platforms only	2781	ev_win32.c required on win32 platforms only
2657		2782
2658	ev_select.c only when select backend is enabled (which is enabled by default)	2783	ev_select.c only when select backend is enabled (which is enabled by default)
2659	ev_poll.c only when poll backend is enabled (disabled by default)	2784	ev_poll.c only when poll backend is enabled (disabled by default)
2660	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2785	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2661	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2786	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2662	ev_port.c only when the solaris port backend is enabled (disabled by default)	2787	ev_port.c only when the solaris port backend is enabled (disabled by default)
2663		2788
2664	F<ev.c> includes the backend files directly when enabled, so you only need	2789	F<ev.c> includes the backend files directly when enabled, so you only need
2665	to compile this single file.	2790	to compile this single file.
2666		2791
2667	=head3 LIBEVENT COMPATIBILITY API	2792	=head3 LIBEVENT COMPATIBILITY API
2668		2793
2669	To include the libevent compatibility API, also include:	2794	To include the libevent compatibility API, also include:
2670		2795
2671	#include "event.c"	2796	#include "event.c"
2672		2797
2673	in the file including F<ev.c>, and:	2798	in the file including F<ev.c>, and:
2674		2799
2675	#include "event.h"	2800	#include "event.h"
2676		2801
2677	in the files that want to use the libevent API. This also includes F<ev.h>.	2802	in the files that want to use the libevent API. This also includes F<ev.h>.
2678		2803
2679	You need the following additional files for this:	2804	You need the following additional files for this:
2680		2805
2681	event.h	2806	event.h
2682	event.c	2807	event.c
2683		2808
2684	=head3 AUTOCONF SUPPORT	2809	=head3 AUTOCONF SUPPORT
2685		2810
2686	Instead of using C<EV_STANDALONE=1> and providing your config in	2811	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2687	whatever way you want, you can also C<m4_include([libev.m4])> in your	2812	whatever way you want, you can also C<m4_include([libev.m4])> in your
2688	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2813	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2689	include F<config.h> and configure itself accordingly.	2814	include F<config.h> and configure itself accordingly.
2690		2815
2691	For this of course you need the m4 file:	2816	For this of course you need the m4 file:
2692		2817
2693	libev.m4	2818	libev.m4
2694		2819
2695	=head2 PREPROCESSOR SYMBOLS/MACROS	2820	=head2 PREPROCESSOR SYMBOLS/MACROS
2696		2821
2697	Libev can be configured via a variety of preprocessor symbols you have to define	2822	Libev can be configured via a variety of preprocessor symbols you have to
2698	before including any of its files. The default is not to build for multiplicity	2823	define before including any of its files. The default in the absence of
2699	and only include the select backend.	2824	autoconf is noted for every option.
2700		2825
2701	=over 4	2826	=over 4
2702		2827
2703	=item EV_STANDALONE	2828	=item EV_STANDALONE
2704		2829
…		…
2709	F<event.h> that are not directly supported by the libev core alone.	2834	F<event.h> that are not directly supported by the libev core alone.
2710		2835
2711	=item EV_USE_MONOTONIC	2836	=item EV_USE_MONOTONIC
2712		2837
2713	If defined to be C<1>, libev will try to detect the availability of the	2838	If defined to be C<1>, libev will try to detect the availability of the
2714	monotonic clock option at both compiletime and runtime. Otherwise no use	2839	monotonic clock option at both compile time and runtime. Otherwise no use
2715	of the monotonic clock option will be attempted. If you enable this, you	2840	of the monotonic clock option will be attempted. If you enable this, you
2716	usually have to link against librt or something similar. Enabling it when	2841	usually have to link against librt or something similar. Enabling it when
2717	the functionality isn't available is safe, though, although you have	2842	the functionality isn't available is safe, though, although you have
2718	to make sure you link against any libraries where the C<clock_gettime>	2843	to make sure you link against any libraries where the C<clock_gettime>
2719	function is hiding in (often F<-lrt>).	2844	function is hiding in (often F<-lrt>).
2720		2845
2721	=item EV_USE_REALTIME	2846	=item EV_USE_REALTIME
2722		2847
2723	If defined to be C<1>, libev will try to detect the availability of the	2848	If defined to be C<1>, libev will try to detect the availability of the
2724	realtime clock option at compiletime (and assume its availability at	2849	real-time clock option at compile time (and assume its availability at
2725	runtime if successful). Otherwise no use of the realtime clock option will	2850	runtime if successful). Otherwise no use of the real-time clock option will
2726	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2851	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2727	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2852	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2728	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2853	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2729		2854
2730	=item EV_USE_NANOSLEEP	2855	=item EV_USE_NANOSLEEP
2731		2856
2732	If defined to be C<1>, libev will assume that C<nanosleep ()> is available	2857	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
2733	and will use it for delays. Otherwise it will use C<select ()>.	2858	and will use it for delays. Otherwise it will use C<select ()>.
2734		2859
		2860	=item EV_USE_EVENTFD
		2861
		2862	If defined to be C<1>, then libev will assume that C<eventfd ()> is
		2863	available and will probe for kernel support at runtime. This will improve
		2864	C<ev_signal> and C<ev_async> performance and reduce resource consumption.
		2865	If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
		2866	2.7 or newer, otherwise disabled.
		2867
2735	=item EV_USE_SELECT	2868	=item EV_USE_SELECT
2736		2869
2737	If undefined or defined to be C<1>, libev will compile in support for the	2870	If undefined or defined to be C<1>, libev will compile in support for the
2738	C<select>(2) backend. No attempt at autodetection will be done: if no	2871	C<select>(2) backend. No attempt at auto-detection will be done: if no
2739	other method takes over, select will be it. Otherwise the select backend	2872	other method takes over, select will be it. Otherwise the select backend
2740	will not be compiled in.	2873	will not be compiled in.
2741		2874
2742	=item EV_SELECT_USE_FD_SET	2875	=item EV_SELECT_USE_FD_SET
2743		2876
2744	If defined to C<1>, then the select backend will use the system C<fd_set>	2877	If defined to C<1>, then the select backend will use the system C<fd_set>
2745	structure. This is useful if libev doesn't compile due to a missing	2878	structure. This is useful if libev doesn't compile due to a missing
2746	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	2879	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
2747	exotic systems. This usually limits the range of file descriptors to some	2880	exotic systems. This usually limits the range of file descriptors to some
2748	low limit such as 1024 or might have other limitations (winsocket only	2881	low limit such as 1024 or might have other limitations (winsocket only
2749	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	2882	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2750	influence the size of the C<fd_set> used.	2883	influence the size of the C<fd_set> used.
2751		2884
…		…
2775		2908
2776	=item EV_USE_EPOLL	2909	=item EV_USE_EPOLL
2777		2910
2778	If defined to be C<1>, libev will compile in support for the Linux	2911	If defined to be C<1>, libev will compile in support for the Linux
2779	C<epoll>(7) backend. Its availability will be detected at runtime,	2912	C<epoll>(7) backend. Its availability will be detected at runtime,
2780	otherwise another method will be used as fallback. This is the	2913	otherwise another method will be used as fallback. This is the preferred
2781	preferred backend for GNU/Linux systems.	2914	backend for GNU/Linux systems. If undefined, it will be enabled if the
		2915	headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2782		2916
2783	=item EV_USE_KQUEUE	2917	=item EV_USE_KQUEUE
2784		2918
2785	If defined to be C<1>, libev will compile in support for the BSD style	2919	If defined to be C<1>, libev will compile in support for the BSD style
2786	C<kqueue>(2) backend. Its actual availability will be detected at runtime,	2920	C<kqueue>(2) backend. Its actual availability will be detected at runtime,
…		…
2799	otherwise another method will be used as fallback. This is the preferred	2933	otherwise another method will be used as fallback. This is the preferred
2800	backend for Solaris 10 systems.	2934	backend for Solaris 10 systems.
2801		2935
2802	=item EV_USE_DEVPOLL	2936	=item EV_USE_DEVPOLL
2803		2937
2804	reserved for future expansion, works like the USE symbols above.	2938	Reserved for future expansion, works like the USE symbols above.
2805		2939
2806	=item EV_USE_INOTIFY	2940	=item EV_USE_INOTIFY
2807		2941
2808	If defined to be C<1>, libev will compile in support for the Linux inotify	2942	If defined to be C<1>, libev will compile in support for the Linux inotify
2809	interface to speed up C<ev_stat> watchers. Its actual availability will	2943	interface to speed up C<ev_stat> watchers. Its actual availability will
2810	be detected at runtime.	2944	be detected at runtime. If undefined, it will be enabled if the headers
		2945	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2811		2946
2812	=item EV_ATOMIC_T	2947	=item EV_ATOMIC_T
2813		2948
2814	Libev requires an integer type (suitable for storing C<0> or C<1>) whose	2949	Libev requires an integer type (suitable for storing C<0> or C<1>) whose
2815	access is atomic with respect to other threads or signal contexts. No such	2950	access is atomic with respect to other threads or signal contexts. No such
2816	type is easily found in the C language, so you can provide your own type	2951	type is easily found in the C language, so you can provide your own type
2817	that you know is safe for your purposes. It is used both for signal handler "locking"	2952	that you know is safe for your purposes. It is used both for signal handler "locking"
2818	as well as for signal and thread safety in C<ev_async> watchers.	2953	as well as for signal and thread safety in C<ev_async> watchers.
2819		2954
2820	In the absense of this define, libev will use C<sig_atomic_t volatile>	2955	In the absence of this define, libev will use C<sig_atomic_t volatile>
2821	(from F<signal.h>), which is usually good enough on most platforms.	2956	(from F<signal.h>), which is usually good enough on most platforms.
2822		2957
2823	=item EV_H	2958	=item EV_H
2824		2959
2825	The name of the F<ev.h> header file used to include it. The default if	2960	The name of the F<ev.h> header file used to include it. The default if
…		…
2864	When doing priority-based operations, libev usually has to linearly search	2999	When doing priority-based operations, libev usually has to linearly search
2865	all the priorities, so having many of them (hundreds) uses a lot of space	3000	all the priorities, so having many of them (hundreds) uses a lot of space
2866	and time, so using the defaults of five priorities (-2 .. +2) is usually	3001	and time, so using the defaults of five priorities (-2 .. +2) is usually
2867	fine.	3002	fine.
2868		3003
2869	If your embedding app does not need any priorities, defining these both to	3004	If your embedding application does not need any priorities, defining these both to
2870	C<0> will save some memory and cpu.	3005	C<0> will save some memory and CPU.
2871		3006
2872	=item EV_PERIODIC_ENABLE	3007	=item EV_PERIODIC_ENABLE
2873		3008
2874	If undefined or defined to be C<1>, then periodic timers are supported. If	3009	If undefined or defined to be C<1>, then periodic timers are supported. If
2875	defined to be C<0>, then they are not. Disabling them saves a few kB of	3010	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
2902	defined to be C<0>, then they are not.	3037	defined to be C<0>, then they are not.
2903		3038
2904	=item EV_MINIMAL	3039	=item EV_MINIMAL
2905		3040
2906	If you need to shave off some kilobytes of code at the expense of some	3041	If you need to shave off some kilobytes of code at the expense of some
2907	speed, define this symbol to C<1>. Currently only used for gcc to override	3042	speed, define this symbol to C<1>. Currently this is used to override some
2908	some inlining decisions, saves roughly 30% codesize of amd64.	3043	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3044	much smaller 2-heap for timer management over the default 4-heap.
2909		3045
2910	=item EV_PID_HASHSIZE	3046	=item EV_PID_HASHSIZE
2911		3047
2912	C<ev_child> watchers use a small hash table to distribute workload by	3048	C<ev_child> watchers use a small hash table to distribute workload by
2913	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3049	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
…		…
2920	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	3056	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2921	usually more than enough. If you need to manage thousands of C<ev_stat>	3057	usually more than enough. If you need to manage thousands of C<ev_stat>
2922	watchers you might want to increase this value (I<must> be a power of	3058	watchers you might want to increase this value (I<must> be a power of
2923	two).	3059	two).
2924		3060
		3061	=item EV_USE_4HEAP
		3062
		3063	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3064	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3065	to C<1>. The 4-heap uses more complicated (longer) code but has
		3066	noticeably faster performance with many (thousands) of watchers.
		3067
		3068	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3069	(disabled).
		3070
		3071	=item EV_HEAP_CACHE_AT
		3072
		3073	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3074	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3075	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3076	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3077	but avoids random read accesses on heap changes. This improves performance
		3078	noticeably with with many (hundreds) of watchers.
		3079
		3080	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3081	(disabled).
		3082
		3083	=item EV_VERIFY
		3084
		3085	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3086	be done: If set to C<0>, no internal verification code will be compiled
		3087	in. If set to C<1>, then verification code will be compiled in, but not
		3088	called. If set to C<2>, then the internal verification code will be
		3089	called once per loop, which can slow down libev. If set to C<3>, then the
		3090	verification code will be called very frequently, which will slow down
		3091	libev considerably.
		3092
		3093	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3094	C<0.>
		3095
2925	=item EV_COMMON	3096	=item EV_COMMON
2926		3097
2927	By default, all watchers have a C<void *data> member. By redefining	3098	By default, all watchers have a C<void *data> member. By redefining
2928	this macro to a something else you can include more and other types of	3099	this macro to a something else you can include more and other types of
2929	members. You have to define it each time you include one of the files,	3100	members. You have to define it each time you include one of the files,
2930	though, and it must be identical each time.	3101	though, and it must be identical each time.
2931		3102
2932	For example, the perl EV module uses something like this:	3103	For example, the perl EV module uses something like this:
2933		3104
2934	#define EV_COMMON \	3105	#define EV_COMMON \
2935	SV *self; /* contains this struct */ \	3106	SV *self; /* contains this struct */ \
2936	SV *cb_sv, *fh /* note no trailing ";" */	3107	SV *cb_sv, *fh /* note no trailing ";" */
2937		3108
2938	=item EV_CB_DECLARE (type)	3109	=item EV_CB_DECLARE (type)
2939		3110
2940	=item EV_CB_INVOKE (watcher, revents)	3111	=item EV_CB_INVOKE (watcher, revents)
2941		3112
…		…
2948	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3119	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2949	method calls instead of plain function calls in C++.	3120	method calls instead of plain function calls in C++.
2950		3121
2951	=head2 EXPORTED API SYMBOLS	3122	=head2 EXPORTED API SYMBOLS
2952		3123
2953	If you need to re-export the API (e.g. via a dll) and you need a list of	3124	If you need to re-export the API (e.g. via a DLL) and you need a list of
2954	exported symbols, you can use the provided F<Symbol.*> files which list	3125	exported symbols, you can use the provided F<Symbol.*> files which list
2955	all public symbols, one per line:	3126	all public symbols, one per line:
2956		3127
2957	Symbols.ev for libev proper	3128	Symbols.ev for libev proper
2958	Symbols.event for the libevent emulation	3129	Symbols.event for the libevent emulation
2959		3130
2960	This can also be used to rename all public symbols to avoid clashes with	3131	This can also be used to rename all public symbols to avoid clashes with
2961	multiple versions of libev linked together (which is obviously bad in	3132	multiple versions of libev linked together (which is obviously bad in
2962	itself, but sometimes it is inconvinient to avoid this).	3133	itself, but sometimes it is inconvenient to avoid this).
2963		3134
2964	A sed command like this will create wrapper C<#define>'s that you need to	3135	A sed command like this will create wrapper C<#define>'s that you need to
2965	include before including F<ev.h>:	3136	include before including F<ev.h>:
2966		3137
2967	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3138	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
2984	file.	3155	file.
2985		3156
2986	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3157	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2987	that everybody includes and which overrides some configure choices:	3158	that everybody includes and which overrides some configure choices:
2988		3159
2989	#define EV_MINIMAL 1	3160	#define EV_MINIMAL 1
2990	#define EV_USE_POLL 0	3161	#define EV_USE_POLL 0
2991	#define EV_MULTIPLICITY 0	3162	#define EV_MULTIPLICITY 0
2992	#define EV_PERIODIC_ENABLE 0	3163	#define EV_PERIODIC_ENABLE 0
2993	#define EV_STAT_ENABLE 0	3164	#define EV_STAT_ENABLE 0
2994	#define EV_FORK_ENABLE 0	3165	#define EV_FORK_ENABLE 0
2995	#define EV_CONFIG_H <config.h>	3166	#define EV_CONFIG_H <config.h>
2996	#define EV_MINPRI 0	3167	#define EV_MINPRI 0
2997	#define EV_MAXPRI 0	3168	#define EV_MAXPRI 0
2998		3169
2999	#include "ev++.h"	3170	#include "ev++.h"
3000		3171
3001	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3172	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3002		3173
3003	#include "ev_cpp.h"	3174	#include "ev_cpp.h"
3004	#include "ev.c"	3175	#include "ev.c"
		3176
		3177
		3178	=head1 THREADS AND COROUTINES
		3179
		3180	=head2 THREADS
		3181
		3182	Libev itself is completely thread-safe, but it uses no locking. This
		3183	means that you can use as many loops as you want in parallel, as long as
		3184	only one thread ever calls into one libev function with the same loop
		3185	parameter.
		3186
		3187	Or put differently: calls with different loop parameters can be done in
		3188	parallel from multiple threads, calls with the same loop parameter must be
		3189	done serially (but can be done from different threads, as long as only one
		3190	thread ever is inside a call at any point in time, e.g. by using a mutex
		3191	per loop).
		3192
		3193	If you want to know which design is best for your problem, then I cannot
		3194	help you but by giving some generic advice:
		3195
		3196	=over 4
		3197
		3198	=item * most applications have a main thread: use the default libev loop
		3199	in that thread, or create a separate thread running only the default loop.
		3200
		3201	This helps integrating other libraries or software modules that use libev
		3202	themselves and don't care/know about threading.
		3203
		3204	=item * one loop per thread is usually a good model.
		3205
		3206	Doing this is almost never wrong, sometimes a better-performance model
		3207	exists, but it is always a good start.
		3208
		3209	=item * other models exist, such as the leader/follower pattern, where one
		3210	loop is handed through multiple threads in a kind of round-robin fashion.
		3211
		3212	Choosing a model is hard - look around, learn, know that usually you can do
		3213	better than you currently do :-)
		3214
		3215	=item * often you need to talk to some other thread which blocks in the
		3216	event loop - C<ev_async> watchers can be used to wake them up from other
		3217	threads safely (or from signal contexts...).
		3218
		3219	=back
		3220
		3221	=head2 COROUTINES
		3222
		3223	Libev is much more accommodating to coroutines ("cooperative threads"):
		3224	libev fully supports nesting calls to it's functions from different
		3225	coroutines (e.g. you can call C<ev_loop> on the same loop from two
		3226	different coroutines and switch freely between both coroutines running the
		3227	loop, as long as you don't confuse yourself). The only exception is that
		3228	you must not do this from C<ev_periodic> reschedule callbacks.
		3229
		3230	Care has been invested into making sure that libev does not keep local
		3231	state inside C<ev_loop>, and other calls do not usually allow coroutine
		3232	switches.
3005		3233
3006		3234
3007	=head1 COMPLEXITIES	3235	=head1 COMPLEXITIES
3008		3236
3009	In this section the complexities of (many of) the algorithms used inside	3237	In this section the complexities of (many of) the algorithms used inside
…		…
3041	correct watcher to remove. The lists are usually short (you don't usually	3269	correct watcher to remove. The lists are usually short (you don't usually
3042	have many watchers waiting for the same fd or signal).	3270	have many watchers waiting for the same fd or signal).
3043		3271
3044	=item Finding the next timer in each loop iteration: O(1)	3272	=item Finding the next timer in each loop iteration: O(1)
3045		3273
3046	By virtue of using a binary heap, the next timer is always found at the	3274	By virtue of using a binary or 4-heap, the next timer is always found at a
3047	beginning of the storage array.	3275	fixed position in the storage array.
3048		3276
3049	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3277	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3050		3278
3051	A change means an I/O watcher gets started or stopped, which requires	3279	A change means an I/O watcher gets started or stopped, which requires
3052	libev to recalculate its status (and possibly tell the kernel, depending	3280	libev to recalculate its status (and possibly tell the kernel, depending
3053	on backend and wether C<ev_io_set> was used).	3281	on backend and whether C<ev_io_set> was used).
3054		3282
3055	=item Activating one watcher (putting it into the pending state): O(1)	3283	=item Activating one watcher (putting it into the pending state): O(1)
3056		3284
3057	=item Priority handling: O(number_of_priorities)	3285	=item Priority handling: O(number_of_priorities)
3058		3286
…		…
3065		3293
3066	=item Processing ev_async_send: O(number_of_async_watchers)	3294	=item Processing ev_async_send: O(number_of_async_watchers)
3067		3295
3068	=item Processing signals: O(max_signal_number)	3296	=item Processing signals: O(max_signal_number)
3069		3297
3070	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3298	Sending involves a system call I<iff> there were no other C<ev_async_send>
3071	calls in the current loop iteration. Checking for async and signal events	3299	calls in the current loop iteration. Checking for async and signal events
3072	involves iterating over all running async watchers or all signal numbers.	3300	involves iterating over all running async watchers or all signal numbers.
3073		3301
3074	=back	3302	=back
3075		3303
3076		3304
3077	=head1 Win32 platform limitations and workarounds	3305	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3078		3306
3079	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3307	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3080	requires, and its I/O model is fundamentally incompatible with the POSIX	3308	requires, and its I/O model is fundamentally incompatible with the POSIX
3081	model. Libev still offers limited functionality on this platform in	3309	model. Libev still offers limited functionality on this platform in
3082	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3310	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3083	descriptors. This only applies when using Win32 natively, not when using	3311	descriptors. This only applies when using Win32 natively, not when using
3084	e.g. cygwin.	3312	e.g. cygwin.
3085		3313
		3314	Lifting these limitations would basically require the full
		3315	re-implementation of the I/O system. If you are into these kinds of
		3316	things, then note that glib does exactly that for you in a very portable
		3317	way (note also that glib is the slowest event library known to man).
		3318
3086	There is no supported compilation method available on windows except	3319	There is no supported compilation method available on windows except
3087	embedding it into other applications.	3320	embedding it into other applications.
3088		3321
		3322	Not a libev limitation but worth mentioning: windows apparently doesn't
		3323	accept large writes: instead of resulting in a partial write, windows will
		3324	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3325	so make sure you only write small amounts into your sockets (less than a
		3326	megabyte seems safe, but thsi apparently depends on the amount of memory
		3327	available).
		3328
3089	Due to the many, low, and arbitrary limits on the win32 platform and the	3329	Due to the many, low, and arbitrary limits on the win32 platform and
3090	abysmal performance of winsockets, using a large number of sockets is not	3330	the abysmal performance of winsockets, using a large number of sockets
3091	recommended (and not reasonable). If your program needs to use more than	3331	is not recommended (and not reasonable). If your program needs to use
3092	a hundred or so sockets, then likely it needs to use a totally different	3332	more than a hundred or so sockets, then likely it needs to use a totally
3093	implementation for windows, as libev offers the POSIX model, which cannot	3333	different implementation for windows, as libev offers the POSIX readiness
3094	be implemented efficiently on windows (microsoft monopoly games).	3334	notification model, which cannot be implemented efficiently on windows
		3335	(Microsoft monopoly games).
		3336
		3337	A typical way to use libev under windows is to embed it (see the embedding
		3338	section for details) and use the following F<evwrap.h> header file instead
		3339	of F<ev.h>:
		3340
		3341	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3342	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3343
		3344	#include "ev.h"
		3345
		3346	And compile the following F<evwrap.c> file into your project (make sure
		3347	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3348
		3349	#include "evwrap.h"
		3350	#include "ev.c"
3095		3351
3096	=over 4	3352	=over 4
3097		3353
3098	=item The winsocket select function	3354	=item The winsocket select function
3099		3355
3100	The winsocket C<select> function doesn't follow POSIX in that it requires	3356	The winsocket C<select> function doesn't follow POSIX in that it
3101	socket I<handles> and not socket I<file descriptors>. This makes select	3357	requires socket I<handles> and not socket I<file descriptors> (it is
3102	very inefficient, and also requires a mapping from file descriptors	3358	also extremely buggy). This makes select very inefficient, and also
3103	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,	3359	requires a mapping from file descriptors to socket handles (the Microsoft
3104	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor	3360	C runtime provides the function C<_open_osfhandle> for this). See the
3105	symbols for more info.	3361	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3362	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3106		3363
3107	The configuration for a "naked" win32 using the microsoft runtime	3364	The configuration for a "naked" win32 using the Microsoft runtime
3108	libraries and raw winsocket select is:	3365	libraries and raw winsocket select is:
3109		3366
3110	#define EV_USE_SELECT 1	3367	#define EV_USE_SELECT 1
3111	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3368	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3112		3369
3113	Note that winsockets handling of fd sets is O(n), so you can easily get a	3370	Note that winsockets handling of fd sets is O(n), so you can easily get a
3114	complexity in the O(n²) range when using win32.	3371	complexity in the O(n²) range when using win32.
3115		3372
3116	=item Limited number of file descriptors	3373	=item Limited number of file descriptors
3117		3374
3118	Windows has numerous arbitrary (and low) limits on things. Early versions	3375	Windows has numerous arbitrary (and low) limits on things.
3119	of winsocket's select only supported waiting for a max. of C<64> handles	3376
		3377	Early versions of winsocket's select only supported waiting for a maximum
3120	(probably owning to the fact that all windows kernels can only wait for	3378	of C<64> handles (probably owning to the fact that all windows kernels
3121	C<64> things at the same time internally; microsoft recommends spawning a	3379	can only wait for C<64> things at the same time internally; Microsoft
3122	chain of threads and wait for 63 handles and the previous thread in each).	3380	recommends spawning a chain of threads and wait for 63 handles and the
		3381	previous thread in each. Great).
3123		3382
3124	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3383	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3125	to some high number (e.g. C<2048>) before compiling the winsocket select	3384	to some high number (e.g. C<2048>) before compiling the winsocket select
3126	call (which might be in libev or elsewhere, for example, perl does its own	3385	call (which might be in libev or elsewhere, for example, perl does its own
3127	select emulation on windows).	3386	select emulation on windows).
3128		3387
3129	Another limit is the number of file descriptors in the microsoft runtime	3388	Another limit is the number of file descriptors in the Microsoft runtime
3130	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3389	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3131	or something like this inside microsoft). You can increase this by calling	3390	or something like this inside Microsoft). You can increase this by calling
3132	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3391	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3133	arbitrary limit), but is broken in many versions of the microsoft runtime	3392	arbitrary limit), but is broken in many versions of the Microsoft runtime
3134	libraries.	3393	libraries.
3135		3394
3136	This might get you to about C<512> or C<2048> sockets (depending on	3395	This might get you to about C<512> or C<2048> sockets (depending on
3137	windows version and/or the phase of the moon). To get more, you need to	3396	windows version and/or the phase of the moon). To get more, you need to
3138	wrap all I/O functions and provide your own fd management, but the cost of	3397	wrap all I/O functions and provide your own fd management, but the cost of
3139	calling select (O(n²)) will likely make this unworkable.	3398	calling select (O(n²)) will likely make this unworkable.
3140		3399
3141	=back	3400	=back
3142		3401
3143		3402
		3403	=head1 PORTABILITY REQUIREMENTS
		3404
		3405	In addition to a working ISO-C implementation, libev relies on a few
		3406	additional extensions:
		3407
		3408	=over 4
		3409
		3410	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3411	calling conventions regardless of C<ev_watcher_type *>.
		3412
		3413	Libev assumes not only that all watcher pointers have the same internal
		3414	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3415	assumes that the same (machine) code can be used to call any watcher
		3416	callback: The watcher callbacks have different type signatures, but libev
		3417	calls them using an C<ev_watcher *> internally.
		3418
		3419	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3420
		3421	The type C<sig_atomic_t volatile> (or whatever is defined as
		3422	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3423	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3424	believed to be sufficiently portable.
		3425
		3426	=item C<sigprocmask> must work in a threaded environment
		3427
		3428	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3429	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3430	pthread implementations will either allow C<sigprocmask> in the "main
		3431	thread" or will block signals process-wide, both behaviours would
		3432	be compatible with libev. Interaction between C<sigprocmask> and
		3433	C<pthread_sigmask> could complicate things, however.
		3434
		3435	The most portable way to handle signals is to block signals in all threads
		3436	except the initial one, and run the default loop in the initial thread as
		3437	well.
		3438
		3439	=item C<long> must be large enough for common memory allocation sizes
		3440
		3441	To improve portability and simplify using libev, libev uses C<long>
		3442	internally instead of C<size_t> when allocating its data structures. On
		3443	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3444	is still at least 31 bits everywhere, which is enough for hundreds of
		3445	millions of watchers.
		3446
		3447	=item C<double> must hold a time value in seconds with enough accuracy
		3448
		3449	The type C<double> is used to represent timestamps. It is required to
		3450	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3451	enough for at least into the year 4000. This requirement is fulfilled by
		3452	implementations implementing IEEE 754 (basically all existing ones).
		3453
		3454	=back
		3455
		3456	If you know of other additional requirements drop me a note.
		3457
		3458
		3459	=head1 COMPILER WARNINGS
		3460
		3461	Depending on your compiler and compiler settings, you might get no or a
		3462	lot of warnings when compiling libev code. Some people are apparently
		3463	scared by this.
		3464
		3465	However, these are unavoidable for many reasons. For one, each compiler
		3466	has different warnings, and each user has different tastes regarding
		3467	warning options. "Warn-free" code therefore cannot be a goal except when
		3468	targeting a specific compiler and compiler-version.
		3469
		3470	Another reason is that some compiler warnings require elaborate
		3471	workarounds, or other changes to the code that make it less clear and less
		3472	maintainable.
		3473
		3474	And of course, some compiler warnings are just plain stupid, or simply
		3475	wrong (because they don't actually warn about the condition their message
		3476	seems to warn about).
		3477
		3478	While libev is written to generate as few warnings as possible,
		3479	"warn-free" code is not a goal, and it is recommended not to build libev
		3480	with any compiler warnings enabled unless you are prepared to cope with
		3481	them (e.g. by ignoring them). Remember that warnings are just that:
		3482	warnings, not errors, or proof of bugs.
		3483
		3484
		3485	=head1 VALGRIND
		3486
		3487	Valgrind has a special section here because it is a popular tool that is
		3488	highly useful, but valgrind reports are very hard to interpret.
		3489
		3490	If you think you found a bug (memory leak, uninitialised data access etc.)
		3491	in libev, then check twice: If valgrind reports something like:
		3492
		3493	==2274== definitely lost: 0 bytes in 0 blocks.
		3494	==2274== possibly lost: 0 bytes in 0 blocks.
		3495	==2274== still reachable: 256 bytes in 1 blocks.
		3496
		3497	Then there is no memory leak. Similarly, under some circumstances,
		3498	valgrind might report kernel bugs as if it were a bug in libev, or it
		3499	might be confused (it is a very good tool, but only a tool).
		3500
		3501	If you are unsure about something, feel free to contact the mailing list
		3502	with the full valgrind report and an explanation on why you think this is
		3503	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3504	no bug" answer and take the chance of learning how to interpret valgrind
		3505	properly.
		3506
		3507	If you need, for some reason, empty reports from valgrind for your project
		3508	I suggest using suppression lists.
		3509
		3510
3144	=head1 AUTHOR	3511	=head1 AUTHOR
3145		3512
3146	Marc Lehmann <libev@schmorp.de>.	3513	Marc Lehmann <libev@schmorp.de>.
3147		3514

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