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Revision 1.142 by root, Sun Apr 6 09:53:18 2008 UTC vs.
Revision 1.174 by root, Mon Aug 18 23:23:45 2008 UTC

…		…
2		2
3	libev - a high performance full-featured event loop written in C	3	libev - a high performance full-featured event loop written in C
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
9	=head2 EXAMPLE PROGRAM	9	=head2 EXAMPLE PROGRAM
10		10
11	// a single header file is required	11	// a single header file is required
12	#include <ev.h>	12	#include <ev.h>
13		13
14	// every watcher type has its own typedef'd struct	14	// every watcher type has its own typedef'd struct
15	// with the name ev_<type>	15	// with the name ev_<type>
16	ev_io stdin_watcher;	16	ev_io stdin_watcher;
17	ev_timer timeout_watcher;	17	ev_timer timeout_watcher;
18		18
19	// all watcher callbacks have a similar signature	19	// all watcher callbacks have a similar signature
20	// this callback is called when data is readable on stdin	20	// this callback is called when data is readable on stdin
21	static void	21	static void
22	stdin_cb (EV_P_ struct ev_io *w, int revents)	22	stdin_cb (EV_P_ struct ev_io *w, int revents)
23	{	23	{
24	puts ("stdin ready");	24	puts ("stdin ready");
25	// for one-shot events, one must manually stop the watcher	25	// for one-shot events, one must manually stop the watcher
26	// with its corresponding stop function.	26	// with its corresponding stop function.
27	ev_io_stop (EV_A_ w);	27	ev_io_stop (EV_A_ w);
28		28
29	// this causes all nested ev_loop's to stop iterating	29	// this causes all nested ev_loop's to stop iterating
30	ev_unloop (EV_A_ EVUNLOOP_ALL);	30	ev_unloop (EV_A_ EVUNLOOP_ALL);
31	}	31	}
32		32
33	// another callback, this time for a time-out	33	// another callback, this time for a time-out
34	static void	34	static void
35	timeout_cb (EV_P_ struct ev_timer *w, int revents)	35	timeout_cb (EV_P_ struct ev_timer *w, int revents)
36	{	36	{
37	puts ("timeout");	37	puts ("timeout");
38	// this causes the innermost ev_loop to stop iterating	38	// this causes the innermost ev_loop to stop iterating
39	ev_unloop (EV_A_ EVUNLOOP_ONE);	39	ev_unloop (EV_A_ EVUNLOOP_ONE);
40	}	40	}
41		41
42	int	42	int
43	main (void)	43	main (void)
44	{	44	{
45	// use the default event loop unless you have special needs	45	// use the default event loop unless you have special needs
46	struct ev_loop *loop = ev_default_loop (0);	46	struct ev_loop *loop = ev_default_loop (0);
47		47
48	// initialise an io watcher, then start it	48	// initialise an io watcher, then start it
49	// this one will watch for stdin to become readable	49	// this one will watch for stdin to become readable
50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
51	ev_io_start (loop, &stdin_watcher);	51	ev_io_start (loop, &stdin_watcher);
52		52
53	// initialise a timer watcher, then start it	53	// initialise a timer watcher, then start it
54	// simple non-repeating 5.5 second timeout	54	// simple non-repeating 5.5 second timeout
55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
56	ev_timer_start (loop, &timeout_watcher);	56	ev_timer_start (loop, &timeout_watcher);
57		57
58	// now wait for events to arrive	58	// now wait for events to arrive
59	ev_loop (loop, 0);	59	ev_loop (loop, 0);
60		60
61	// unloop was called, so exit	61	// unloop was called, so exit
62	return 0;	62	return 0;
63	}	63	}
64		64
65	=head1 DESCRIPTION	65	=head1 DESCRIPTION
66		66
67	The newest version of this document is also available as an html-formatted	67	The newest version of this document is also available as an html-formatted
68	web page you might find easier to navigate when reading it for the first	68	web page you might find easier to navigate when reading it for the first
69	time: L<http://cvs.schmorp.de/libev/ev.html>.	69	time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>.
70		70
71	Libev is an event loop: you register interest in certain events (such as a	71	Libev is an event loop: you register interest in certain events (such as a
72	file descriptor being readable or a timeout occurring), and it will manage	72	file descriptor being readable or a timeout occurring), and it will manage
73	these event sources and provide your program with events.	73	these event sources and provide your program with events.
74		74
…		…
113	Libev represents time as a single floating point number, representing the	113	Libev represents time as a single floating point number, representing the
114	(fractional) number of seconds since the (POSIX) epoch (somewhere near	114	(fractional) number of seconds since the (POSIX) epoch (somewhere near
115	the beginning of 1970, details are complicated, don't ask). This type is	115	the beginning of 1970, details are complicated, don't ask). This type is
116	called C<ev_tstamp>, which is what you should use too. It usually aliases	116	called C<ev_tstamp>, which is what you should use too. It usually aliases
117	to the C<double> type in C, and when you need to do any calculations on	117	to the C<double> type in C, and when you need to do any calculations on
118	it, you should treat it as some floatingpoint value. Unlike the name	118	it, you should treat it as some floating point value. Unlike the name
119	component C<stamp> might indicate, it is also used for time differences	119	component C<stamp> might indicate, it is also used for time differences
120	throughout libev.	120	throughout libev.
		121
		122	=head1 ERROR HANDLING
		123
		124	Libev knows three classes of errors: operating system errors, usage errors
		125	and internal errors (bugs).
		126
		127	When libev catches an operating system error it cannot handle (for example
		128	a system call indicating a condition libev cannot fix), it calls the callback
		129	set via C<ev_set_syserr_cb>, which is supposed to fix the problem or
		130	abort. The default is to print a diagnostic message and to call C<abort
		131	()>.
		132
		133	When libev detects a usage error such as a negative timer interval, then
		134	it will print a diagnostic message and abort (via the C<assert> mechanism,
		135	so C<NDEBUG> will disable this checking): these are programming errors in
		136	the libev caller and need to be fixed there.
		137
		138	Libev also has a few internal error-checking C<assert>ions, and also has
		139	extensive consistency checking code. These do not trigger under normal
		140	circumstances, as they indicate either a bug in libev or worse.
		141
121		142
122	=head1 GLOBAL FUNCTIONS	143	=head1 GLOBAL FUNCTIONS
123		144
124	These functions can be called anytime, even before initialising the	145	These functions can be called anytime, even before initialising the
125	library in any way.	146	library in any way.
…		…
134		155
135	=item ev_sleep (ev_tstamp interval)	156	=item ev_sleep (ev_tstamp interval)
136		157
137	Sleep for the given interval: The current thread will be blocked until	158	Sleep for the given interval: The current thread will be blocked until
138	either it is interrupted or the given time interval has passed. Basically	159	either it is interrupted or the given time interval has passed. Basically
139	this is a subsecond-resolution C<sleep ()>.	160	this is a sub-second-resolution C<sleep ()>.
140		161
141	=item int ev_version_major ()	162	=item int ev_version_major ()
142		163
143	=item int ev_version_minor ()	164	=item int ev_version_minor ()
144		165
…		…
157	not a problem.	178	not a problem.
158		179
159	Example: Make sure we haven't accidentally been linked against the wrong	180	Example: Make sure we haven't accidentally been linked against the wrong
160	version.	181	version.
161		182
162	assert (("libev version mismatch",	183	assert (("libev version mismatch",
163	ev_version_major () == EV_VERSION_MAJOR	184	ev_version_major () == EV_VERSION_MAJOR
164	&& ev_version_minor () >= EV_VERSION_MINOR));	185	&& ev_version_minor () >= EV_VERSION_MINOR));
165		186
166	=item unsigned int ev_supported_backends ()	187	=item unsigned int ev_supported_backends ()
167		188
168	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>	189	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>
169	value) compiled into this binary of libev (independent of their	190	value) compiled into this binary of libev (independent of their
…		…
171	a description of the set values.	192	a description of the set values.
172		193
173	Example: make sure we have the epoll method, because yeah this is cool and	194	Example: make sure we have the epoll method, because yeah this is cool and
174	a must have and can we have a torrent of it please!!!11	195	a must have and can we have a torrent of it please!!!11
175		196
176	assert (("sorry, no epoll, no sex",	197	assert (("sorry, no epoll, no sex",
177	ev_supported_backends () & EVBACKEND_EPOLL));	198	ev_supported_backends () & EVBACKEND_EPOLL));
178		199
179	=item unsigned int ev_recommended_backends ()	200	=item unsigned int ev_recommended_backends ()
180		201
181	Return the set of all backends compiled into this binary of libev and also	202	Return the set of all backends compiled into this binary of libev and also
182	recommended for this platform. This set is often smaller than the one	203	recommended for this platform. This set is often smaller than the one
183	returned by C<ev_supported_backends>, as for example kqueue is broken on	204	returned by C<ev_supported_backends>, as for example kqueue is broken on
184	most BSDs and will not be autodetected unless you explicitly request it	205	most BSDs and will not be auto-detected unless you explicitly request it
185	(assuming you know what you are doing). This is the set of backends that	206	(assuming you know what you are doing). This is the set of backends that
186	libev will probe for if you specify no backends explicitly.	207	libev will probe for if you specify no backends explicitly.
187		208
188	=item unsigned int ev_embeddable_backends ()	209	=item unsigned int ev_embeddable_backends ()
189		210
…		…
196	See the description of C<ev_embed> watchers for more info.	217	See the description of C<ev_embed> watchers for more info.
197		218
198	=item ev_set_allocator (void *(*cb)(void *ptr, long size))	219	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
199		220
200	Sets the allocation function to use (the prototype is similar - the	221	Sets the allocation function to use (the prototype is similar - the
201	semantics is identical - to the realloc C function). It is used to	222	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
202	allocate and free memory (no surprises here). If it returns zero when	223	used to allocate and free memory (no surprises here). If it returns zero
203	memory needs to be allocated, the library might abort or take some	224	when memory needs to be allocated (C<size != 0>), the library might abort
204	potentially destructive action. The default is your system realloc	225	or take some potentially destructive action.
205	function.	226
		227	Since some systems (at least OpenBSD and Darwin) fail to implement
		228	correct C<realloc> semantics, libev will use a wrapper around the system
		229	C<realloc> and C<free> functions by default.
206		230
207	You could override this function in high-availability programs to, say,	231	You could override this function in high-availability programs to, say,
208	free some memory if it cannot allocate memory, to use a special allocator,	232	free some memory if it cannot allocate memory, to use a special allocator,
209	or even to sleep a while and retry until some memory is available.	233	or even to sleep a while and retry until some memory is available.
210		234
211	Example: Replace the libev allocator with one that waits a bit and then	235	Example: Replace the libev allocator with one that waits a bit and then
212	retries).	236	retries (example requires a standards-compliant C<realloc>).
213		237
214	static void *	238	static void *
215	persistent_realloc (void *ptr, size_t size)	239	persistent_realloc (void *ptr, size_t size)
216	{	240	{
217	for (;;)	241	for (;;)
…		…
228	...	252	...
229	ev_set_allocator (persistent_realloc);	253	ev_set_allocator (persistent_realloc);
230		254
231	=item ev_set_syserr_cb (void (*cb)(const char *msg));	255	=item ev_set_syserr_cb (void (*cb)(const char *msg));
232		256
233	Set the callback function to call on a retryable syscall error (such	257	Set the callback function to call on a retryable system call error (such
234	as failed select, poll, epoll_wait). The message is a printable string	258	as failed select, poll, epoll_wait). The message is a printable string
235	indicating the system call or subsystem causing the problem. If this	259	indicating the system call or subsystem causing the problem. If this
236	callback is set, then libev will expect it to remedy the sitution, no	260	callback is set, then libev will expect it to remedy the situation, no
237	matter what, when it returns. That is, libev will generally retry the	261	matter what, when it returns. That is, libev will generally retry the
238	requested operation, or, if the condition doesn't go away, do bad stuff	262	requested operation, or, if the condition doesn't go away, do bad stuff
239	(such as abort).	263	(such as abort).
240		264
241	Example: This is basically the same thing that libev does internally, too.	265	Example: This is basically the same thing that libev does internally, too.
…		…
255	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	279	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP
256		280
257	An event loop is described by a C<struct ev_loop *>. The library knows two	281	An event loop is described by a C<struct ev_loop *>. The library knows two
258	types of such loops, the I<default> loop, which supports signals and child	282	types of such loops, the I<default> loop, which supports signals and child
259	events, and dynamically created loops which do not.	283	events, and dynamically created loops which do not.
260
261	If you use threads, a common model is to run the default event loop
262	in your main thread (or in a separate thread) and for each thread you
263	create, you also create another event loop. Libev itself does no locking
264	whatsoever, so if you mix calls to the same event loop in different
265	threads, make sure you lock (this is usually a bad idea, though, even if
266	done correctly, because it's hideous and inefficient).
267		284
268	=over 4	285	=over 4
269		286
270	=item struct ev_loop *ev_default_loop (unsigned int flags)	287	=item struct ev_loop *ev_default_loop (unsigned int flags)
271		288
…		…
281	from multiple threads, you have to lock (note also that this is unlikely,	298	from multiple threads, you have to lock (note also that this is unlikely,
282	as loops cannot bes hared easily between threads anyway).	299	as loops cannot bes hared easily between threads anyway).
283		300
284	The default loop is the only loop that can handle C<ev_signal> and	301	The default loop is the only loop that can handle C<ev_signal> and
285	C<ev_child> watchers, and to do this, it always registers a handler	302	C<ev_child> watchers, and to do this, it always registers a handler
286	for C<SIGCHLD>. If this is a problem for your app you can either	303	for C<SIGCHLD>. If this is a problem for your application you can either
287	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	304	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
288	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	305	can simply overwrite the C<SIGCHLD> signal handler I<after> calling
289	C<ev_default_init>.	306	C<ev_default_init>.
290		307
291	The flags argument can be used to specify special behaviour or specific	308	The flags argument can be used to specify special behaviour or specific
…		…
300	The default flags value. Use this if you have no clue (it's the right	317	The default flags value. Use this if you have no clue (it's the right
301	thing, believe me).	318	thing, believe me).
302		319
303	=item C<EVFLAG_NOENV>	320	=item C<EVFLAG_NOENV>
304		321
305	If this flag bit is ored into the flag value (or the program runs setuid	322	If this flag bit is or'ed into the flag value (or the program runs setuid
306	or setgid) then libev will I<not> look at the environment variable	323	or setgid) then libev will I<not> look at the environment variable
307	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	324	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
308	override the flags completely if it is found in the environment. This is	325	override the flags completely if it is found in the environment. This is
309	useful to try out specific backends to test their performance, or to work	326	useful to try out specific backends to test their performance, or to work
310	around bugs.	327	around bugs.
…		…
317		334
318	This works by calling C<getpid ()> on every iteration of the loop,	335	This works by calling C<getpid ()> on every iteration of the loop,
319	and thus this might slow down your event loop if you do a lot of loop	336	and thus this might slow down your event loop if you do a lot of loop
320	iterations and little real work, but is usually not noticeable (on my	337	iterations and little real work, but is usually not noticeable (on my
321	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	338	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
322	without a syscall and thus I<very> fast, but my GNU/Linux system also has	339	without a system call and thus I<very> fast, but my GNU/Linux system also has
323	C<pthread_atfork> which is even faster).	340	C<pthread_atfork> which is even faster).
324		341
325	The big advantage of this flag is that you can forget about fork (and	342	The big advantage of this flag is that you can forget about fork (and
326	forget about forgetting to tell libev about forking) when you use this	343	forget about forgetting to tell libev about forking) when you use this
327	flag.	344	flag.
328		345
329	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>	346	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
330	environment variable.	347	environment variable.
331		348
332	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	349	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
333		350
334	This is your standard select(2) backend. Not I<completely> standard, as	351	This is your standard select(2) backend. Not I<completely> standard, as
…		…
336	but if that fails, expect a fairly low limit on the number of fds when	353	but if that fails, expect a fairly low limit on the number of fds when
337	using this backend. It doesn't scale too well (O(highest_fd)), but its	354	using this backend. It doesn't scale too well (O(highest_fd)), but its
338	usually the fastest backend for a low number of (low-numbered :) fds.	355	usually the fastest backend for a low number of (low-numbered :) fds.
339		356
340	To get good performance out of this backend you need a high amount of	357	To get good performance out of this backend you need a high amount of
341	parallelity (most of the file descriptors should be busy). If you are	358	parallelism (most of the file descriptors should be busy). If you are
342	writing a server, you should C<accept ()> in a loop to accept as many	359	writing a server, you should C<accept ()> in a loop to accept as many
343	connections as possible during one iteration. You might also want to have	360	connections as possible during one iteration. You might also want to have
344	a look at C<ev_set_io_collect_interval ()> to increase the amount of	361	a look at C<ev_set_io_collect_interval ()> to increase the amount of
345	readyness notifications you get per iteration.	362	readiness notifications you get per iteration.
346		363
347	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	364	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
348		365
349	And this is your standard poll(2) backend. It's more complicated	366	And this is your standard poll(2) backend. It's more complicated
350	than select, but handles sparse fds better and has no artificial	367	than select, but handles sparse fds better and has no artificial
…		…
358	For few fds, this backend is a bit little slower than poll and select,	375	For few fds, this backend is a bit little slower than poll and select,
359	but it scales phenomenally better. While poll and select usually scale	376	but it scales phenomenally better. While poll and select usually scale
360	like O(total_fds) where n is the total number of fds (or the highest fd),	377	like O(total_fds) where n is the total number of fds (or the highest fd),
361	epoll scales either O(1) or O(active_fds). The epoll design has a number	378	epoll scales either O(1) or O(active_fds). The epoll design has a number
362	of shortcomings, such as silently dropping events in some hard-to-detect	379	of shortcomings, such as silently dropping events in some hard-to-detect
363	cases and requiring a syscall per fd change, no fork support and bad	380	cases and requiring a system call per fd change, no fork support and bad
364	support for dup.	381	support for dup.
365		382
366	While stopping, setting and starting an I/O watcher in the same iteration	383	While stopping, setting and starting an I/O watcher in the same iteration
367	will result in some caching, there is still a syscall per such incident	384	will result in some caching, there is still a system call per such incident
368	(because the fd could point to a different file description now), so its	385	(because the fd could point to a different file description now), so its
369	best to avoid that. Also, C<dup ()>'ed file descriptors might not work	386	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
370	very well if you register events for both fds.	387	very well if you register events for both fds.
371		388
372	Please note that epoll sometimes generates spurious notifications, so you	389	Please note that epoll sometimes generates spurious notifications, so you
…		…
375		392
376	Best performance from this backend is achieved by not unregistering all	393	Best performance from this backend is achieved by not unregistering all
377	watchers for a file descriptor until it has been closed, if possible, i.e.	394	watchers for a file descriptor until it has been closed, if possible, i.e.
378	keep at least one watcher active per fd at all times.	395	keep at least one watcher active per fd at all times.
379		396
380	While nominally embeddeble in other event loops, this feature is broken in	397	While nominally embeddable in other event loops, this feature is broken in
381	all kernel versions tested so far.	398	all kernel versions tested so far.
382		399
383	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	400	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
384		401
385	Kqueue deserves special mention, as at the time of this writing, it	402	Kqueue deserves special mention, as at the time of this writing, it
386	was broken on all BSDs except NetBSD (usually it doesn't work reliably	403	was broken on all BSDs except NetBSD (usually it doesn't work reliably
387	with anything but sockets and pipes, except on Darwin, where of course	404	with anything but sockets and pipes, except on Darwin, where of course
388	it's completely useless). For this reason it's not being "autodetected"	405	it's completely useless). For this reason it's not being "auto-detected"
389	unless you explicitly specify it explicitly in the flags (i.e. using	406	unless you explicitly specify it explicitly in the flags (i.e. using
390	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)	407	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
391	system like NetBSD.	408	system like NetBSD.
392		409
393	You still can embed kqueue into a normal poll or select backend and use it	410	You still can embed kqueue into a normal poll or select backend and use it
…		…
395	the target platform). See C<ev_embed> watchers for more info.	412	the target platform). See C<ev_embed> watchers for more info.
396		413
397	It scales in the same way as the epoll backend, but the interface to the	414	It scales in the same way as the epoll backend, but the interface to the
398	kernel is more efficient (which says nothing about its actual speed, of	415	kernel is more efficient (which says nothing about its actual speed, of
399	course). While stopping, setting and starting an I/O watcher does never	416	course). While stopping, setting and starting an I/O watcher does never
400	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to	417	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
401	two event changes per incident, support for C<fork ()> is very bad and it	418	two event changes per incident, support for C<fork ()> is very bad and it
402	drops fds silently in similarly hard-to-detect cases.	419	drops fds silently in similarly hard-to-detect cases.
403		420
404	This backend usually performs well under most conditions.	421	This backend usually performs well under most conditions.
405		422
…		…
420	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	437	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
421		438
422	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	439	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
423	it's really slow, but it still scales very well (O(active_fds)).	440	it's really slow, but it still scales very well (O(active_fds)).
424		441
425	Please note that solaris event ports can deliver a lot of spurious	442	Please note that Solaris event ports can deliver a lot of spurious
426	notifications, so you need to use non-blocking I/O or other means to avoid	443	notifications, so you need to use non-blocking I/O or other means to avoid
427	blocking when no data (or space) is available.	444	blocking when no data (or space) is available.
428		445
429	While this backend scales well, it requires one system call per active	446	While this backend scales well, it requires one system call per active
430	file descriptor per loop iteration. For small and medium numbers of file	447	file descriptor per loop iteration. For small and medium numbers of file
431	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	448	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
432	might perform better.	449	might perform better.
433		450
434	On the positive side, ignoring the spurious readyness notifications, this	451	On the positive side, ignoring the spurious readiness notifications, this
435	backend actually performed to specification in all tests and is fully	452	backend actually performed to specification in all tests and is fully
436	embeddable, which is a rare feat among the OS-specific backends.	453	embeddable, which is a rare feat among the OS-specific backends.
437		454
438	=item C<EVBACKEND_ALL>	455	=item C<EVBACKEND_ALL>
439		456
…		…
443		460
444	It is definitely not recommended to use this flag.	461	It is definitely not recommended to use this flag.
445		462
446	=back	463	=back
447		464
448	If one or more of these are ored into the flags value, then only these	465	If one or more of these are or'ed into the flags value, then only these
449	backends will be tried (in the reverse order as listed here). If none are	466	backends will be tried (in the reverse order as listed here). If none are
450	specified, all backends in C<ev_recommended_backends ()> will be tried.	467	specified, all backends in C<ev_recommended_backends ()> will be tried.
451		468
452	The most typical usage is like this:	469	The most typical usage is like this:
453		470
454	if (!ev_default_loop (0))	471	if (!ev_default_loop (0))
455	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	472	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
456		473
457	Restrict libev to the select and poll backends, and do not allow	474	Restrict libev to the select and poll backends, and do not allow
458	environment settings to be taken into account:	475	environment settings to be taken into account:
459		476
460	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);	477	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
461		478
462	Use whatever libev has to offer, but make sure that kqueue is used if	479	Use whatever libev has to offer, but make sure that kqueue is used if
463	available (warning, breaks stuff, best use only with your own private	480	available (warning, breaks stuff, best use only with your own private
464	event loop and only if you know the OS supports your types of fds):	481	event loop and only if you know the OS supports your types of fds):
465		482
466	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	483	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
467		484
468	=item struct ev_loop *ev_loop_new (unsigned int flags)	485	=item struct ev_loop *ev_loop_new (unsigned int flags)
469		486
470	Similar to C<ev_default_loop>, but always creates a new event loop that is	487	Similar to C<ev_default_loop>, but always creates a new event loop that is
471	always distinct from the default loop. Unlike the default loop, it cannot	488	always distinct from the default loop. Unlike the default loop, it cannot
…		…
476	libev with threads is indeed to create one loop per thread, and using the	493	libev with threads is indeed to create one loop per thread, and using the
477	default loop in the "main" or "initial" thread.	494	default loop in the "main" or "initial" thread.
478		495
479	Example: Try to create a event loop that uses epoll and nothing else.	496	Example: Try to create a event loop that uses epoll and nothing else.
480		497
481	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	498	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
482	if (!epoller)	499	if (!epoller)
483	fatal ("no epoll found here, maybe it hides under your chair");	500	fatal ("no epoll found here, maybe it hides under your chair");
484		501
485	=item ev_default_destroy ()	502	=item ev_default_destroy ()
486		503
487	Destroys the default loop again (frees all memory and kernel state	504	Destroys the default loop again (frees all memory and kernel state
488	etc.). None of the active event watchers will be stopped in the normal	505	etc.). None of the active event watchers will be stopped in the normal
489	sense, so e.g. C<ev_is_active> might still return true. It is your	506	sense, so e.g. C<ev_is_active> might still return true. It is your
490	responsibility to either stop all watchers cleanly yoursef I<before>	507	responsibility to either stop all watchers cleanly yourself I<before>
491	calling this function, or cope with the fact afterwards (which is usually	508	calling this function, or cope with the fact afterwards (which is usually
492	the easiest thing, you can just ignore the watchers and/or C<free ()> them	509	the easiest thing, you can just ignore the watchers and/or C<free ()> them
493	for example).	510	for example).
494		511
495	Note that certain global state, such as signal state, will not be freed by	512	Note that certain global state, such as signal state, will not be freed by
…		…
576	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	593	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle
577	those events and any outstanding ones, but will not block your process in	594	those events and any outstanding ones, but will not block your process in
578	case there are no events and will return after one iteration of the loop.	595	case there are no events and will return after one iteration of the loop.
579		596
580	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	597	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
581	neccessary) and will handle those and any outstanding ones. It will block	598	necessary) and will handle those and any outstanding ones. It will block
582	your process until at least one new event arrives, and will return after	599	your process until at least one new event arrives, and will return after
583	one iteration of the loop. This is useful if you are waiting for some	600	one iteration of the loop. This is useful if you are waiting for some
584	external event in conjunction with something not expressible using other	601	external event in conjunction with something not expressible using other
585	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	602	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
586	usually a better approach for this kind of thing.	603	usually a better approach for this kind of thing.
587		604
588	Here are the gory details of what C<ev_loop> does:	605	Here are the gory details of what C<ev_loop> does:
589		606
590	- Before the first iteration, call any pending watchers.	607	- Before the first iteration, call any pending watchers.
591	* If EVFLAG_FORKCHECK was used, check for a fork.	608	* If EVFLAG_FORKCHECK was used, check for a fork.
592	- If a fork was detected, queue and call all fork watchers.	609	- If a fork was detected (by any means), queue and call all fork watchers.
593	- Queue and call all prepare watchers.	610	- Queue and call all prepare watchers.
594	- If we have been forked, recreate the kernel state.	611	- If we have been forked, detach and recreate the kernel state
		612	as to not disturb the other process.
595	- Update the kernel state with all outstanding changes.	613	- Update the kernel state with all outstanding changes.
596	- Update the "event loop time".	614	- Update the "event loop time" (ev_now ()).
597	- Calculate for how long to sleep or block, if at all	615	- Calculate for how long to sleep or block, if at all
598	(active idle watchers, EVLOOP_NONBLOCK or not having	616	(active idle watchers, EVLOOP_NONBLOCK or not having
599	any active watchers at all will result in not sleeping).	617	any active watchers at all will result in not sleeping).
600	- Sleep if the I/O and timer collect interval say so.	618	- Sleep if the I/O and timer collect interval say so.
601	- Block the process, waiting for any events.	619	- Block the process, waiting for any events.
602	- Queue all outstanding I/O (fd) events.	620	- Queue all outstanding I/O (fd) events.
603	- Update the "event loop time" and do time jump handling.	621	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
604	- Queue all outstanding timers.	622	- Queue all outstanding timers.
605	- Queue all outstanding periodics.	623	- Queue all outstanding periodics.
606	- If no events are pending now, queue all idle watchers.	624	- Unless any events are pending now, queue all idle watchers.
607	- Queue all check watchers.	625	- Queue all check watchers.
608	- Call all queued watchers in reverse order (i.e. check watchers first).	626	- Call all queued watchers in reverse order (i.e. check watchers first).
609	Signals and child watchers are implemented as I/O watchers, and will	627	Signals and child watchers are implemented as I/O watchers, and will
610	be handled here by queueing them when their watcher gets executed.	628	be handled here by queueing them when their watcher gets executed.
611	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	629	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
…		…
616	anymore.	634	anymore.
617		635
618	... queue jobs here, make sure they register event watchers as long	636	... queue jobs here, make sure they register event watchers as long
619	... as they still have work to do (even an idle watcher will do..)	637	... as they still have work to do (even an idle watcher will do..)
620	ev_loop (my_loop, 0);	638	ev_loop (my_loop, 0);
621	... jobs done. yeah!	639	... jobs done or somebody called unloop. yeah!
622		640
623	=item ev_unloop (loop, how)	641	=item ev_unloop (loop, how)
624		642
625	Can be used to make a call to C<ev_loop> return early (but only after it	643	Can be used to make a call to C<ev_loop> return early (but only after it
626	has processed all outstanding events). The C<how> argument must be either	644	has processed all outstanding events). The C<how> argument must be either
…		…
647	respectively).	665	respectively).
648		666
649	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	667	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
650	running when nothing else is active.	668	running when nothing else is active.
651		669
652	struct ev_signal exitsig;	670	struct ev_signal exitsig;
653	ev_signal_init (&exitsig, sig_cb, SIGINT);	671	ev_signal_init (&exitsig, sig_cb, SIGINT);
654	ev_signal_start (loop, &exitsig);	672	ev_signal_start (loop, &exitsig);
655	evf_unref (loop);	673	evf_unref (loop);
656		674
657	Example: For some weird reason, unregister the above signal handler again.	675	Example: For some weird reason, unregister the above signal handler again.
658		676
659	ev_ref (loop);	677	ev_ref (loop);
660	ev_signal_stop (loop, &exitsig);	678	ev_signal_stop (loop, &exitsig);
661		679
662	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	680	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
663		681
664	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	682	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
665		683
666	These advanced functions influence the time that libev will spend waiting	684	These advanced functions influence the time that libev will spend waiting
667	for events. Both are by default C<0>, meaning that libev will try to	685	for events. Both time intervals are by default C<0>, meaning that libev
668	invoke timer/periodic callbacks and I/O callbacks with minimum latency.	686	will try to invoke timer/periodic callbacks and I/O callbacks with minimum
		687	latency.
669		688
670	Setting these to a higher value (the C<interval> I<must> be >= C<0>)	689	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
671	allows libev to delay invocation of I/O and timer/periodic callbacks to	690	allows libev to delay invocation of I/O and timer/periodic callbacks
672	increase efficiency of loop iterations.	691	to increase efficiency of loop iterations (or to increase power-saving
		692	opportunities).
673		693
674	The background is that sometimes your program runs just fast enough to	694	The background is that sometimes your program runs just fast enough to
675	handle one (or very few) event(s) per loop iteration. While this makes	695	handle one (or very few) event(s) per loop iteration. While this makes
676	the program responsive, it also wastes a lot of CPU time to poll for new	696	the program responsive, it also wastes a lot of CPU time to poll for new
677	events, especially with backends like C<select ()> which have a high	697	events, especially with backends like C<select ()> which have a high
…		…
687	to spend more time collecting timeouts, at the expense of increased	707	to spend more time collecting timeouts, at the expense of increased
688	latency (the watcher callback will be called later). C<ev_io> watchers	708	latency (the watcher callback will be called later). C<ev_io> watchers
689	will not be affected. Setting this to a non-null value will not introduce	709	will not be affected. Setting this to a non-null value will not introduce
690	any overhead in libev.	710	any overhead in libev.
691		711
692	Many (busy) programs can usually benefit by setting the io collect	712	Many (busy) programs can usually benefit by setting the I/O collect
693	interval to a value near C<0.1> or so, which is often enough for	713	interval to a value near C<0.1> or so, which is often enough for
694	interactive servers (of course not for games), likewise for timeouts. It	714	interactive servers (of course not for games), likewise for timeouts. It
695	usually doesn't make much sense to set it to a lower value than C<0.01>,	715	usually doesn't make much sense to set it to a lower value than C<0.01>,
696	as this approsaches the timing granularity of most systems.	716	as this approaches the timing granularity of most systems.
		717
		718	Setting the I<timeout collect interval> can improve the opportunity for
		719	saving power, as the program will "bundle" timer callback invocations that
		720	are "near" in time together, by delaying some, thus reducing the number of
		721	times the process sleeps and wakes up again. Another useful technique to
		722	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
		723	they fire on, say, one-second boundaries only.
		724
		725	=item ev_loop_verify (loop)
		726
		727	This function only does something when C<EV_VERIFY> support has been
		728	compiled in. It tries to go through all internal structures and checks
		729	them for validity. If anything is found to be inconsistent, it will print
		730	an error message to standard error and call C<abort ()>.
		731
		732	This can be used to catch bugs inside libev itself: under normal
		733	circumstances, this function will never abort as of course libev keeps its
		734	data structures consistent.
697		735
698	=back	736	=back
699		737
700		738
701	=head1 ANATOMY OF A WATCHER	739	=head1 ANATOMY OF A WATCHER
702		740
703	A watcher is a structure that you create and register to record your	741	A watcher is a structure that you create and register to record your
704	interest in some event. For instance, if you want to wait for STDIN to	742	interest in some event. For instance, if you want to wait for STDIN to
705	become readable, you would create an C<ev_io> watcher for that:	743	become readable, you would create an C<ev_io> watcher for that:
706		744
707	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	745	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
708	{	746	{
709	ev_io_stop (w);	747	ev_io_stop (w);
710	ev_unloop (loop, EVUNLOOP_ALL);	748	ev_unloop (loop, EVUNLOOP_ALL);
711	}	749	}
712		750
713	struct ev_loop *loop = ev_default_loop (0);	751	struct ev_loop *loop = ev_default_loop (0);
714	struct ev_io stdin_watcher;	752	struct ev_io stdin_watcher;
715	ev_init (&stdin_watcher, my_cb);	753	ev_init (&stdin_watcher, my_cb);
716	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	754	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
717	ev_io_start (loop, &stdin_watcher);	755	ev_io_start (loop, &stdin_watcher);
718	ev_loop (loop, 0);	756	ev_loop (loop, 0);
719		757
720	As you can see, you are responsible for allocating the memory for your	758	As you can see, you are responsible for allocating the memory for your
721	watcher structures (and it is usually a bad idea to do this on the stack,	759	watcher structures (and it is usually a bad idea to do this on the stack,
722	although this can sometimes be quite valid).	760	although this can sometimes be quite valid).
723		761
724	Each watcher structure must be initialised by a call to C<ev_init	762	Each watcher structure must be initialised by a call to C<ev_init
725	(watcher *, callback)>, which expects a callback to be provided. This	763	(watcher *, callback)>, which expects a callback to be provided. This
726	callback gets invoked each time the event occurs (or, in the case of io	764	callback gets invoked each time the event occurs (or, in the case of I/O
727	watchers, each time the event loop detects that the file descriptor given	765	watchers, each time the event loop detects that the file descriptor given
728	is readable and/or writable).	766	is readable and/or writable).
729		767
730	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	768	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro
731	with arguments specific to this watcher type. There is also a macro	769	with arguments specific to this watcher type. There is also a macro
…		…
807		845
808	The given async watcher has been asynchronously notified (see C<ev_async>).	846	The given async watcher has been asynchronously notified (see C<ev_async>).
809		847
810	=item C<EV_ERROR>	848	=item C<EV_ERROR>
811		849
812	An unspecified error has occured, the watcher has been stopped. This might	850	An unspecified error has occurred, the watcher has been stopped. This might
813	happen because the watcher could not be properly started because libev	851	happen because the watcher could not be properly started because libev
814	ran out of memory, a file descriptor was found to be closed or any other	852	ran out of memory, a file descriptor was found to be closed or any other
815	problem. You best act on it by reporting the problem and somehow coping	853	problem. You best act on it by reporting the problem and somehow coping
816	with the watcher being stopped.	854	with the watcher being stopped.
817		855
818	Libev will usually signal a few "dummy" events together with an error,	856	Libev will usually signal a few "dummy" events together with an error,
819	for example it might indicate that a fd is readable or writable, and if	857	for example it might indicate that a fd is readable or writable, and if
820	your callbacks is well-written it can just attempt the operation and cope	858	your callbacks is well-written it can just attempt the operation and cope
821	with the error from read() or write(). This will not work in multithreaded	859	with the error from read() or write(). This will not work in multi-threaded
822	programs, though, so beware.	860	programs, though, so beware.
823		861
824	=back	862	=back
825		863
826	=head2 GENERIC WATCHER FUNCTIONS	864	=head2 GENERIC WATCHER FUNCTIONS
…		…
856	Although some watcher types do not have type-specific arguments	894	Although some watcher types do not have type-specific arguments
857	(e.g. C<ev_prepare>) you still need to call its C<set> macro.	895	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
858		896
859	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	897	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
860		898
861	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	899	This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
862	calls into a single call. This is the most convinient method to initialise	900	calls into a single call. This is the most convenient method to initialise
863	a watcher. The same limitations apply, of course.	901	a watcher. The same limitations apply, of course.
864		902
865	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	903	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
866		904
867	Starts (activates) the given watcher. Only active watchers will receive	905	Starts (activates) the given watcher. Only active watchers will receive
…		…
950	to associate arbitrary data with your watcher. If you need more data and	988	to associate arbitrary data with your watcher. If you need more data and
951	don't want to allocate memory and store a pointer to it in that data	989	don't want to allocate memory and store a pointer to it in that data
952	member, you can also "subclass" the watcher type and provide your own	990	member, you can also "subclass" the watcher type and provide your own
953	data:	991	data:
954		992
955	struct my_io	993	struct my_io
956	{	994	{
957	struct ev_io io;	995	struct ev_io io;
958	int otherfd;	996	int otherfd;
959	void *somedata;	997	void *somedata;
960	struct whatever *mostinteresting;	998	struct whatever *mostinteresting;
961	}	999	}
962		1000
963	And since your callback will be called with a pointer to the watcher, you	1001	And since your callback will be called with a pointer to the watcher, you
964	can cast it back to your own type:	1002	can cast it back to your own type:
965		1003
966	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	1004	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
967	{	1005	{
968	struct my_io *w = (struct my_io *)w_;	1006	struct my_io *w = (struct my_io *)w_;
969	...	1007	...
970	}	1008	}
971		1009
972	More interesting and less C-conformant ways of casting your callback type	1010	More interesting and less C-conformant ways of casting your callback type
973	instead have been omitted.	1011	instead have been omitted.
974		1012
975	Another common scenario is having some data structure with multiple	1013	Another common scenario is having some data structure with multiple
976	watchers:	1014	watchers:
977		1015
978	struct my_biggy	1016	struct my_biggy
979	{	1017	{
980	int some_data;	1018	int some_data;
981	ev_timer t1;	1019	ev_timer t1;
982	ev_timer t2;	1020	ev_timer t2;
983	}	1021	}
984		1022
985	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1023	In this case getting the pointer to C<my_biggy> is a bit more complicated,
986	you need to use C<offsetof>:	1024	you need to use C<offsetof>:
987		1025
988	#include <stddef.h>	1026	#include <stddef.h>
989		1027
990	static void	1028	static void
991	t1_cb (EV_P_ struct ev_timer *w, int revents)	1029	t1_cb (EV_P_ struct ev_timer *w, int revents)
992	{	1030	{
993	struct my_biggy big = (struct my_biggy *	1031	struct my_biggy big = (struct my_biggy *
994	(((char *)w) - offsetof (struct my_biggy, t1));	1032	(((char *)w) - offsetof (struct my_biggy, t1));
995	}	1033	}
996		1034
997	static void	1035	static void
998	t2_cb (EV_P_ struct ev_timer *w, int revents)	1036	t2_cb (EV_P_ struct ev_timer *w, int revents)
999	{	1037	{
1000	struct my_biggy big = (struct my_biggy *	1038	struct my_biggy big = (struct my_biggy *
1001	(((char *)w) - offsetof (struct my_biggy, t2));	1039	(((char *)w) - offsetof (struct my_biggy, t2));
1002	}	1040	}
1003		1041
1004		1042
1005	=head1 WATCHER TYPES	1043	=head1 WATCHER TYPES
1006		1044
1007	This section describes each watcher in detail, but will not repeat	1045	This section describes each watcher in detail, but will not repeat
…		…
1036	If you must do this, then force the use of a known-to-be-good backend	1074	If you must do this, then force the use of a known-to-be-good backend
1037	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1075	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
1038	C<EVBACKEND_POLL>).	1076	C<EVBACKEND_POLL>).
1039		1077
1040	Another thing you have to watch out for is that it is quite easy to	1078	Another thing you have to watch out for is that it is quite easy to
1041	receive "spurious" readyness notifications, that is your callback might	1079	receive "spurious" readiness notifications, that is your callback might
1042	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1080	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1043	because there is no data. Not only are some backends known to create a	1081	because there is no data. Not only are some backends known to create a
1044	lot of those (for example solaris ports), it is very easy to get into	1082	lot of those (for example Solaris ports), it is very easy to get into
1045	this situation even with a relatively standard program structure. Thus	1083	this situation even with a relatively standard program structure. Thus
1046	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1084	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1047	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1085	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1048		1086
1049	If you cannot run the fd in non-blocking mode (for example you should not	1087	If you cannot run the fd in non-blocking mode (for example you should not
1050	play around with an Xlib connection), then you have to seperately re-test	1088	play around with an Xlib connection), then you have to separately re-test
1051	whether a file descriptor is really ready with a known-to-be good interface	1089	whether a file descriptor is really ready with a known-to-be good interface
1052	such as poll (fortunately in our Xlib example, Xlib already does this on	1090	such as poll (fortunately in our Xlib example, Xlib already does this on
1053	its own, so its quite safe to use).	1091	its own, so its quite safe to use).
1054		1092
1055	=head3 The special problem of disappearing file descriptors	1093	=head3 The special problem of disappearing file descriptors
…		…
1096	C<EVBACKEND_POLL>.	1134	C<EVBACKEND_POLL>.
1097		1135
1098	=head3 The special problem of SIGPIPE	1136	=head3 The special problem of SIGPIPE
1099		1137
1100	While not really specific to libev, it is easy to forget about SIGPIPE:	1138	While not really specific to libev, it is easy to forget about SIGPIPE:
1101	when reading from a pipe whose other end has been closed, your program	1139	when writing to a pipe whose other end has been closed, your program gets
1102	gets send a SIGPIPE, which, by default, aborts your program. For most	1140	send a SIGPIPE, which, by default, aborts your program. For most programs
1103	programs this is sensible behaviour, for daemons, this is usually	1141	this is sensible behaviour, for daemons, this is usually undesirable.
1104	undesirable.
1105		1142
1106	So when you encounter spurious, unexplained daemon exits, make sure you	1143	So when you encounter spurious, unexplained daemon exits, make sure you
1107	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1144	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1108	somewhere, as that would have given you a big clue).	1145	somewhere, as that would have given you a big clue).
1109		1146
…		…
1115	=item ev_io_init (ev_io *, callback, int fd, int events)	1152	=item ev_io_init (ev_io *, callback, int fd, int events)
1116		1153
1117	=item ev_io_set (ev_io *, int fd, int events)	1154	=item ev_io_set (ev_io *, int fd, int events)
1118		1155
1119	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1156	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1120	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1157	receive events for and events is either C<EV_READ>, C<EV_WRITE> or
1121	C<EV_READ | EV_WRITE> to receive the given events.	1158	C<EV_READ | EV_WRITE> to receive the given events.
1122		1159
1123	=item int fd [read-only]	1160	=item int fd [read-only]
1124		1161
1125	The file descriptor being watched.	1162	The file descriptor being watched.
…		…
1134		1171
1135	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1172	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1136	readable, but only once. Since it is likely line-buffered, you could	1173	readable, but only once. Since it is likely line-buffered, you could
1137	attempt to read a whole line in the callback.	1174	attempt to read a whole line in the callback.
1138		1175
1139	static void	1176	static void
1140	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1177	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1141	{	1178	{
1142	ev_io_stop (loop, w);	1179	ev_io_stop (loop, w);
1143	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1180	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1144	}	1181	}
1145		1182
1146	...	1183	...
1147	struct ev_loop *loop = ev_default_init (0);	1184	struct ev_loop *loop = ev_default_init (0);
1148	struct ev_io stdin_readable;	1185	struct ev_io stdin_readable;
1149	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1186	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1150	ev_io_start (loop, &stdin_readable);	1187	ev_io_start (loop, &stdin_readable);
1151	ev_loop (loop, 0);	1188	ev_loop (loop, 0);
1152		1189
1153		1190
1154	=head2 C<ev_timer> - relative and optionally repeating timeouts	1191	=head2 C<ev_timer> - relative and optionally repeating timeouts
1155		1192
1156	Timer watchers are simple relative timers that generate an event after a	1193	Timer watchers are simple relative timers that generate an event after a
1157	given time, and optionally repeating in regular intervals after that.	1194	given time, and optionally repeating in regular intervals after that.
1158		1195
1159	The timers are based on real time, that is, if you register an event that	1196	The timers are based on real time, that is, if you register an event that
1160	times out after an hour and you reset your system clock to last years	1197	times out after an hour and you reset your system clock to January last
1161	time, it will still time out after (roughly) and hour. "Roughly" because	1198	year, it will still time out after (roughly) and hour. "Roughly" because
1162	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1199	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1163	monotonic clock option helps a lot here).	1200	monotonic clock option helps a lot here).
1164		1201
1165	The relative timeouts are calculated relative to the C<ev_now ()>	1202	The relative timeouts are calculated relative to the C<ev_now ()>
1166	time. This is usually the right thing as this timestamp refers to the time	1203	time. This is usually the right thing as this timestamp refers to the time
…		…
1168	you suspect event processing to be delayed and you I<need> to base the timeout	1205	you suspect event processing to be delayed and you I<need> to base the timeout
1169	on the current time, use something like this to adjust for this:	1206	on the current time, use something like this to adjust for this:
1170		1207
1171	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1208	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1172		1209
1173	The callback is guarenteed to be invoked only when its timeout has passed,	1210	The callback is guaranteed to be invoked only after its timeout has passed,
1174	but if multiple timers become ready during the same loop iteration then	1211	but if multiple timers become ready during the same loop iteration then
1175	order of execution is undefined.	1212	order of execution is undefined.
1176		1213
1177	=head3 Watcher-Specific Functions and Data Members	1214	=head3 Watcher-Specific Functions and Data Members
1178		1215
…		…
1180		1217
1181	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1218	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1182		1219
1183	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1220	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1184		1221
1185	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1222	Configure the timer to trigger after C<after> seconds. If C<repeat>
1186	C<0.>, then it will automatically be stopped. If it is positive, then the	1223	is C<0.>, then it will automatically be stopped once the timeout is
1187	timer will automatically be configured to trigger again C<repeat> seconds	1224	reached. If it is positive, then the timer will automatically be
1188	later, again, and again, until stopped manually.	1225	configured to trigger again C<repeat> seconds later, again, and again,
		1226	until stopped manually.
1189		1227
1190	The timer itself will do a best-effort at avoiding drift, that is, if you	1228	The timer itself will do a best-effort at avoiding drift, that is, if
1191	configure a timer to trigger every 10 seconds, then it will trigger at	1229	you configure a timer to trigger every 10 seconds, then it will normally
1192	exactly 10 second intervals. If, however, your program cannot keep up with	1230	trigger at exactly 10 second intervals. If, however, your program cannot
1193	the timer (because it takes longer than those 10 seconds to do stuff) the	1231	keep up with the timer (because it takes longer than those 10 seconds to
1194	timer will not fire more than once per event loop iteration.	1232	do stuff) the timer will not fire more than once per event loop iteration.
1195		1233
1196	=item ev_timer_again (loop, ev_timer *)	1234	=item ev_timer_again (loop, ev_timer *)
1197		1235
1198	This will act as if the timer timed out and restart it again if it is	1236	This will act as if the timer timed out and restart it again if it is
1199	repeating. The exact semantics are:	1237	repeating. The exact semantics are:
1200		1238
1201	If the timer is pending, its pending status is cleared.	1239	If the timer is pending, its pending status is cleared.
1202		1240
1203	If the timer is started but nonrepeating, stop it (as if it timed out).	1241	If the timer is started but non-repeating, stop it (as if it timed out).
1204		1242
1205	If the timer is repeating, either start it if necessary (with the	1243	If the timer is repeating, either start it if necessary (with the
1206	C<repeat> value), or reset the running timer to the C<repeat> value.	1244	C<repeat> value), or reset the running timer to the C<repeat> value.
1207		1245
1208	This sounds a bit complicated, but here is a useful and typical	1246	This sounds a bit complicated, but here is a useful and typical
1209	example: Imagine you have a tcp connection and you want a so-called idle	1247	example: Imagine you have a TCP connection and you want a so-called idle
1210	timeout, that is, you want to be called when there have been, say, 60	1248	timeout, that is, you want to be called when there have been, say, 60
1211	seconds of inactivity on the socket. The easiest way to do this is to	1249	seconds of inactivity on the socket. The easiest way to do this is to
1212	configure an C<ev_timer> with a C<repeat> value of C<60> and then call	1250	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1213	C<ev_timer_again> each time you successfully read or write some data. If	1251	C<ev_timer_again> each time you successfully read or write some data. If
1214	you go into an idle state where you do not expect data to travel on the	1252	you go into an idle state where you do not expect data to travel on the
…		…
1240		1278
1241	=head3 Examples	1279	=head3 Examples
1242		1280
1243	Example: Create a timer that fires after 60 seconds.	1281	Example: Create a timer that fires after 60 seconds.
1244		1282
1245	static void	1283	static void
1246	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1284	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1247	{	1285	{
1248	.. one minute over, w is actually stopped right here	1286	.. one minute over, w is actually stopped right here
1249	}	1287	}
1250		1288
1251	struct ev_timer mytimer;	1289	struct ev_timer mytimer;
1252	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1290	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1253	ev_timer_start (loop, &mytimer);	1291	ev_timer_start (loop, &mytimer);
1254		1292
1255	Example: Create a timeout timer that times out after 10 seconds of	1293	Example: Create a timeout timer that times out after 10 seconds of
1256	inactivity.	1294	inactivity.
1257		1295
1258	static void	1296	static void
1259	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1297	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1260	{	1298	{
1261	.. ten seconds without any activity	1299	.. ten seconds without any activity
1262	}	1300	}
1263		1301
1264	struct ev_timer mytimer;	1302	struct ev_timer mytimer;
1265	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1303	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1266	ev_timer_again (&mytimer); /* start timer */	1304	ev_timer_again (&mytimer); /* start timer */
1267	ev_loop (loop, 0);	1305	ev_loop (loop, 0);
1268		1306
1269	// and in some piece of code that gets executed on any "activity":	1307	// and in some piece of code that gets executed on any "activity":
1270	// reset the timeout to start ticking again at 10 seconds	1308	// reset the timeout to start ticking again at 10 seconds
1271	ev_timer_again (&mytimer);	1309	ev_timer_again (&mytimer);
1272		1310
1273		1311
1274	=head2 C<ev_periodic> - to cron or not to cron?	1312	=head2 C<ev_periodic> - to cron or not to cron?
1275		1313
1276	Periodic watchers are also timers of a kind, but they are very versatile	1314	Periodic watchers are also timers of a kind, but they are very versatile
1277	(and unfortunately a bit complex).	1315	(and unfortunately a bit complex).
1278		1316
1279	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1317	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
1280	but on wallclock time (absolute time). You can tell a periodic watcher	1318	but on wall clock time (absolute time). You can tell a periodic watcher
1281	to trigger "at" some specific point in time. For example, if you tell a	1319	to trigger after some specific point in time. For example, if you tell a
1282	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1320	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()
1283	+ 10.>) and then reset your system clock to the last year, then it will	1321	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1322	clock to January of the previous year, then it will take more than year
1284	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1323	to trigger the event (unlike an C<ev_timer>, which would still trigger
1285	roughly 10 seconds later).	1324	roughly 10 seconds later as it uses a relative timeout).
1286		1325
1287	They can also be used to implement vastly more complex timers, such as	1326	C<ev_periodic>s can also be used to implement vastly more complex timers,
1288	triggering an event on each midnight, local time or other, complicated,	1327	such as triggering an event on each "midnight, local time", or other
1289	rules.	1328	complicated, rules.
1290		1329
1291	As with timers, the callback is guarenteed to be invoked only when the	1330	As with timers, the callback is guaranteed to be invoked only when the
1292	time (C<at>) has been passed, but if multiple periodic timers become ready	1331	time (C<at>) has passed, but if multiple periodic timers become ready
1293	during the same loop iteration then order of execution is undefined.	1332	during the same loop iteration then order of execution is undefined.
1294		1333
1295	=head3 Watcher-Specific Functions and Data Members	1334	=head3 Watcher-Specific Functions and Data Members
1296		1335
1297	=over 4	1336	=over 4
…		…
1305		1344
1306	=over 4	1345	=over 4
1307		1346
1308	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1347	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1309		1348
1310	In this configuration the watcher triggers an event at the wallclock time	1349	In this configuration the watcher triggers an event after the wall clock
1311	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1350	time C<at> has passed and doesn't repeat. It will not adjust when a time
1312	that is, if it is to be run at January 1st 2011 then it will run when the	1351	jump occurs, that is, if it is to be run at January 1st 2011 then it will
1313	system time reaches or surpasses this time.	1352	run when the system time reaches or surpasses this time.
1314		1353
1315	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1354	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1316		1355
1317	In this mode the watcher will always be scheduled to time out at the next	1356	In this mode the watcher will always be scheduled to time out at the next
1318	C<at + N * interval> time (for some integer N, which can also be negative)	1357	C<at + N * interval> time (for some integer N, which can also be negative)
1319	and then repeat, regardless of any time jumps.	1358	and then repeat, regardless of any time jumps.
1320		1359
1321	This can be used to create timers that do not drift with respect to system	1360	This can be used to create timers that do not drift with respect to system
1322	time:	1361	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1362	the hour:
1323		1363
1324	ev_periodic_set (&periodic, 0., 3600., 0);	1364	ev_periodic_set (&periodic, 0., 3600., 0);
1325		1365
1326	This doesn't mean there will always be 3600 seconds in between triggers,	1366	This doesn't mean there will always be 3600 seconds in between triggers,
1327	but only that the the callback will be called when the system time shows a	1367	but only that the callback will be called when the system time shows a
1328	full hour (UTC), or more correctly, when the system time is evenly divisible	1368	full hour (UTC), or more correctly, when the system time is evenly divisible
1329	by 3600.	1369	by 3600.
1330		1370
1331	Another way to think about it (for the mathematically inclined) is that	1371	Another way to think about it (for the mathematically inclined) is that
1332	C<ev_periodic> will try to run the callback in this mode at the next possible	1372	C<ev_periodic> will try to run the callback in this mode at the next possible
1333	time where C<time = at (mod interval)>, regardless of any time jumps.	1373	time where C<time = at (mod interval)>, regardless of any time jumps.
1334		1374
1335	For numerical stability it is preferable that the C<at> value is near	1375	For numerical stability it is preferable that the C<at> value is near
1336	C<ev_now ()> (the current time), but there is no range requirement for	1376	C<ev_now ()> (the current time), but there is no range requirement for
1337	this value.	1377	this value, and in fact is often specified as zero.
		1378
		1379	Note also that there is an upper limit to how often a timer can fire (CPU
		1380	speed for example), so if C<interval> is very small then timing stability
		1381	will of course deteriorate. Libev itself tries to be exact to be about one
		1382	millisecond (if the OS supports it and the machine is fast enough).
1338		1383
1339	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1384	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1340		1385
1341	In this mode the values for C<interval> and C<at> are both being	1386	In this mode the values for C<interval> and C<at> are both being
1342	ignored. Instead, each time the periodic watcher gets scheduled, the	1387	ignored. Instead, each time the periodic watcher gets scheduled, the
1343	reschedule callback will be called with the watcher as first, and the	1388	reschedule callback will be called with the watcher as first, and the
1344	current time as second argument.	1389	current time as second argument.
1345		1390
1346	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1391	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1347	ever, or make any event loop modifications>. If you need to stop it,	1392	ever, or make ANY event loop modifications whatsoever>.
1348	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1349	starting an C<ev_prepare> watcher, which is legal).
1350		1393
		1394	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1395	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1396	only event loop modification you are allowed to do).
		1397
1351	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1398	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1352	ev_tstamp now)>, e.g.:	1399	*w, ev_tstamp now)>, e.g.:
1353		1400
1354	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1401	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1355	{	1402	{
1356	return now + 60.;	1403	return now + 60.;
1357	}	1404	}
…		…
1359	It must return the next time to trigger, based on the passed time value	1406	It must return the next time to trigger, based on the passed time value
1360	(that is, the lowest time value larger than to the second argument). It	1407	(that is, the lowest time value larger than to the second argument). It
1361	will usually be called just before the callback will be triggered, but	1408	will usually be called just before the callback will be triggered, but
1362	might be called at other times, too.	1409	might be called at other times, too.
1363		1410
1364	NOTE: I<< This callback must always return a time that is later than the	1411	NOTE: I<< This callback must always return a time that is higher than or
1365	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.	1412	equal to the passed C<now> value >>.
1366		1413
1367	This can be used to create very complex timers, such as a timer that	1414	This can be used to create very complex timers, such as a timer that
1368	triggers on each midnight, local time. To do this, you would calculate the	1415	triggers on "next midnight, local time". To do this, you would calculate the
1369	next midnight after C<now> and return the timestamp value for this. How	1416	next midnight after C<now> and return the timestamp value for this. How
1370	you do this is, again, up to you (but it is not trivial, which is the main	1417	you do this is, again, up to you (but it is not trivial, which is the main
1371	reason I omitted it as an example).	1418	reason I omitted it as an example).
1372		1419
1373	=back	1420	=back
…		…
1377	Simply stops and restarts the periodic watcher again. This is only useful	1424	Simply stops and restarts the periodic watcher again. This is only useful
1378	when you changed some parameters or the reschedule callback would return	1425	when you changed some parameters or the reschedule callback would return
1379	a different time than the last time it was called (e.g. in a crond like	1426	a different time than the last time it was called (e.g. in a crond like
1380	program when the crontabs have changed).	1427	program when the crontabs have changed).
1381		1428
		1429	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1430
		1431	When active, returns the absolute time that the watcher is supposed to
		1432	trigger next.
		1433
1382	=item ev_tstamp offset [read-write]	1434	=item ev_tstamp offset [read-write]
1383		1435
1384	When repeating, this contains the offset value, otherwise this is the	1436	When repeating, this contains the offset value, otherwise this is the
1385	absolute point in time (the C<at> value passed to C<ev_periodic_set>).	1437	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1386		1438
…		…
1397		1449
1398	The current reschedule callback, or C<0>, if this functionality is	1450	The current reschedule callback, or C<0>, if this functionality is
1399	switched off. Can be changed any time, but changes only take effect when	1451	switched off. Can be changed any time, but changes only take effect when
1400	the periodic timer fires or C<ev_periodic_again> is being called.	1452	the periodic timer fires or C<ev_periodic_again> is being called.
1401		1453
1402	=item ev_tstamp at [read-only]
1403
1404	When active, contains the absolute time that the watcher is supposed to
1405	trigger next.
1406
1407	=back	1454	=back
1408		1455
1409	=head3 Examples	1456	=head3 Examples
1410		1457
1411	Example: Call a callback every hour, or, more precisely, whenever the	1458	Example: Call a callback every hour, or, more precisely, whenever the
1412	system clock is divisible by 3600. The callback invocation times have	1459	system clock is divisible by 3600. The callback invocation times have
1413	potentially a lot of jittering, but good long-term stability.	1460	potentially a lot of jitter, but good long-term stability.
1414		1461
1415	static void	1462	static void
1416	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1463	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1417	{	1464	{
1418	... its now a full hour (UTC, or TAI or whatever your clock follows)	1465	... its now a full hour (UTC, or TAI or whatever your clock follows)
1419	}	1466	}
1420		1467
1421	struct ev_periodic hourly_tick;	1468	struct ev_periodic hourly_tick;
1422	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1469	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1423	ev_periodic_start (loop, &hourly_tick);	1470	ev_periodic_start (loop, &hourly_tick);
1424		1471
1425	Example: The same as above, but use a reschedule callback to do it:	1472	Example: The same as above, but use a reschedule callback to do it:
1426		1473
1427	#include <math.h>	1474	#include <math.h>
1428		1475
1429	static ev_tstamp	1476	static ev_tstamp
1430	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1477	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1431	{	1478	{
1432	return fmod (now, 3600.) + 3600.;	1479	return fmod (now, 3600.) + 3600.;
1433	}	1480	}
1434		1481
1435	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1482	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1436		1483
1437	Example: Call a callback every hour, starting now:	1484	Example: Call a callback every hour, starting now:
1438		1485
1439	struct ev_periodic hourly_tick;	1486	struct ev_periodic hourly_tick;
1440	ev_periodic_init (&hourly_tick, clock_cb,	1487	ev_periodic_init (&hourly_tick, clock_cb,
1441	fmod (ev_now (loop), 3600.), 3600., 0);	1488	fmod (ev_now (loop), 3600.), 3600., 0);
1442	ev_periodic_start (loop, &hourly_tick);	1489	ev_periodic_start (loop, &hourly_tick);
1443		1490
1444		1491
1445	=head2 C<ev_signal> - signal me when a signal gets signalled!	1492	=head2 C<ev_signal> - signal me when a signal gets signalled!
1446		1493
1447	Signal watchers will trigger an event when the process receives a specific	1494	Signal watchers will trigger an event when the process receives a specific
…		…
1455	as you don't register any with libev). Similarly, when the last signal	1502	as you don't register any with libev). Similarly, when the last signal
1456	watcher for a signal is stopped libev will reset the signal handler to	1503	watcher for a signal is stopped libev will reset the signal handler to
1457	SIG_DFL (regardless of what it was set to before).	1504	SIG_DFL (regardless of what it was set to before).
1458		1505
1459	If possible and supported, libev will install its handlers with	1506	If possible and supported, libev will install its handlers with
1460	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1507	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1461	interrupted. If you have a problem with syscalls getting interrupted by	1508	interrupted. If you have a problem with system calls getting interrupted by
1462	signals you can block all signals in an C<ev_check> watcher and unblock	1509	signals you can block all signals in an C<ev_check> watcher and unblock
1463	them in an C<ev_prepare> watcher.	1510	them in an C<ev_prepare> watcher.
1464		1511
1465	=head3 Watcher-Specific Functions and Data Members	1512	=head3 Watcher-Specific Functions and Data Members
1466		1513
…		…
1481		1528
1482	=head3 Examples	1529	=head3 Examples
1483		1530
1484	Example: Try to exit cleanly on SIGINT and SIGTERM.	1531	Example: Try to exit cleanly on SIGINT and SIGTERM.
1485		1532
1486	static void	1533	static void
1487	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1534	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1488	{	1535	{
1489	ev_unloop (loop, EVUNLOOP_ALL);	1536	ev_unloop (loop, EVUNLOOP_ALL);
1490	}	1537	}
1491		1538
1492	struct ev_signal signal_watcher;	1539	struct ev_signal signal_watcher;
1493	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1540	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1494	ev_signal_start (loop, &sigint_cb);	1541	ev_signal_start (loop, &sigint_cb);
1495		1542
1496		1543
1497	=head2 C<ev_child> - watch out for process status changes	1544	=head2 C<ev_child> - watch out for process status changes
1498		1545
1499	Child watchers trigger when your process receives a SIGCHLD in response to	1546	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1501	is permissible to install a child watcher I<after> the child has been	1548	is permissible to install a child watcher I<after> the child has been
1502	forked (which implies it might have already exited), as long as the event	1549	forked (which implies it might have already exited), as long as the event
1503	loop isn't entered (or is continued from a watcher).	1550	loop isn't entered (or is continued from a watcher).
1504		1551
1505	Only the default event loop is capable of handling signals, and therefore	1552	Only the default event loop is capable of handling signals, and therefore
1506	you can only rgeister child watchers in the default event loop.	1553	you can only register child watchers in the default event loop.
1507		1554
1508	=head3 Process Interaction	1555	=head3 Process Interaction
1509		1556
1510	Libev grabs C<SIGCHLD> as soon as the default event loop is	1557	Libev grabs C<SIGCHLD> as soon as the default event loop is
1511	initialised. This is necessary to guarantee proper behaviour even if	1558	initialised. This is necessary to guarantee proper behaviour even if
1512	the first child watcher is started after the child exits. The occurance	1559	the first child watcher is started after the child exits. The occurrence
1513	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1560	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1514	synchronously as part of the event loop processing. Libev always reaps all	1561	synchronously as part of the event loop processing. Libev always reaps all
1515	children, even ones not watched.	1562	children, even ones not watched.
1516		1563
1517	=head3 Overriding the Built-In Processing	1564	=head3 Overriding the Built-In Processing
…		…
1521	handler, you can override it easily by installing your own handler for	1568	handler, you can override it easily by installing your own handler for
1522	C<SIGCHLD> after initialising the default loop, and making sure the	1569	C<SIGCHLD> after initialising the default loop, and making sure the
1523	default loop never gets destroyed. You are encouraged, however, to use an	1570	default loop never gets destroyed. You are encouraged, however, to use an
1524	event-based approach to child reaping and thus use libev's support for	1571	event-based approach to child reaping and thus use libev's support for
1525	that, so other libev users can use C<ev_child> watchers freely.	1572	that, so other libev users can use C<ev_child> watchers freely.
		1573
		1574	=head3 Stopping the Child Watcher
		1575
		1576	Currently, the child watcher never gets stopped, even when the
		1577	child terminates, so normally one needs to stop the watcher in the
		1578	callback. Future versions of libev might stop the watcher automatically
		1579	when a child exit is detected.
1526		1580
1527	=head3 Watcher-Specific Functions and Data Members	1581	=head3 Watcher-Specific Functions and Data Members
1528		1582
1529	=over 4	1583	=over 4
1530		1584
…		…
1559	=head3 Examples	1613	=head3 Examples
1560		1614
1561	Example: C<fork()> a new process and install a child handler to wait for	1615	Example: C<fork()> a new process and install a child handler to wait for
1562	its completion.	1616	its completion.
1563		1617
1564	ev_child cw;	1618	ev_child cw;
1565		1619
1566	static void	1620	static void
1567	child_cb (EV_P_ struct ev_child *w, int revents)	1621	child_cb (EV_P_ struct ev_child *w, int revents)
1568	{	1622	{
1569	ev_child_stop (EV_A_ w);	1623	ev_child_stop (EV_A_ w);
1570	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1624	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1571	}	1625	}
1572		1626
1573	pid_t pid = fork ();	1627	pid_t pid = fork ();
1574		1628
1575	if (pid < 0)	1629	if (pid < 0)
1576	// error	1630	// error
1577	else if (pid == 0)	1631	else if (pid == 0)
1578	{	1632	{
1579	// the forked child executes here	1633	// the forked child executes here
1580	exit (1);	1634	exit (1);
1581	}	1635	}
1582	else	1636	else
1583	{	1637	{
1584	ev_child_init (&cw, child_cb, pid, 0);	1638	ev_child_init (&cw, child_cb, pid, 0);
1585	ev_child_start (EV_DEFAULT_ &cw);	1639	ev_child_start (EV_DEFAULT_ &cw);
1586	}	1640	}
1587		1641
1588		1642
1589	=head2 C<ev_stat> - did the file attributes just change?	1643	=head2 C<ev_stat> - did the file attributes just change?
1590		1644
1591	This watches a filesystem path for attribute changes. That is, it calls	1645	This watches a file system path for attribute changes. That is, it calls
1592	C<stat> regularly (or when the OS says it changed) and sees if it changed	1646	C<stat> regularly (or when the OS says it changed) and sees if it changed
1593	compared to the last time, invoking the callback if it did.	1647	compared to the last time, invoking the callback if it did.
1594		1648
1595	The path does not need to exist: changing from "path exists" to "path does	1649	The path does not need to exist: changing from "path exists" to "path does
1596	not exist" is a status change like any other. The condition "path does	1650	not exist" is a status change like any other. The condition "path does
…		…
1614	as even with OS-supported change notifications, this can be	1668	as even with OS-supported change notifications, this can be
1615	resource-intensive.	1669	resource-intensive.
1616		1670
1617	At the time of this writing, only the Linux inotify interface is	1671	At the time of this writing, only the Linux inotify interface is
1618	implemented (implementing kqueue support is left as an exercise for the	1672	implemented (implementing kqueue support is left as an exercise for the
		1673	reader, note, however, that the author sees no way of implementing ev_stat
1619	reader). Inotify will be used to give hints only and should not change the	1674	semantics with kqueue). Inotify will be used to give hints only and should
1620	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1675	not change the semantics of C<ev_stat> watchers, which means that libev
1621	to fall back to regular polling again even with inotify, but changes are	1676	sometimes needs to fall back to regular polling again even with inotify,
1622	usually detected immediately, and if the file exists there will be no	1677	but changes are usually detected immediately, and if the file exists there
1623	polling.	1678	will be no polling.
1624		1679
1625	=head3 ABI Issues (Largefile Support)	1680	=head3 ABI Issues (Largefile Support)
1626		1681
1627	Libev by default (unless the user overrides this) uses the default	1682	Libev by default (unless the user overrides this) uses the default
1628	compilation environment, which means that on systems with optionally	1683	compilation environment, which means that on systems with large file
1629	disabled large file support, you get the 32 bit version of the stat	1684	support disabled by default, you get the 32 bit version of the stat
1630	structure. When using the library from programs that change the ABI to	1685	structure. When using the library from programs that change the ABI to
1631	use 64 bit file offsets the programs will fail. In that case you have to	1686	use 64 bit file offsets the programs will fail. In that case you have to
1632	compile libev with the same flags to get binary compatibility. This is	1687	compile libev with the same flags to get binary compatibility. This is
1633	obviously the case with any flags that change the ABI, but the problem is	1688	obviously the case with any flags that change the ABI, but the problem is
1634	most noticably with ev_stat and largefile support.	1689	most noticeably disabled with ev_stat and large file support.
		1690
		1691	The solution for this is to lobby your distribution maker to make large
		1692	file interfaces available by default (as e.g. FreeBSD does) and not
		1693	optional. Libev cannot simply switch on large file support because it has
		1694	to exchange stat structures with application programs compiled using the
		1695	default compilation environment.
1635		1696
1636	=head3 Inotify	1697	=head3 Inotify
1637		1698
1638	When C<inotify (7)> support has been compiled into libev (generally only	1699	When C<inotify (7)> support has been compiled into libev (generally only
1639	available on Linux) and present at runtime, it will be used to speed up	1700	available on Linux) and present at runtime, it will be used to speed up
1640	change detection where possible. The inotify descriptor will be created lazily	1701	change detection where possible. The inotify descriptor will be created lazily
1641	when the first C<ev_stat> watcher is being started.	1702	when the first C<ev_stat> watcher is being started.
1642		1703
1643	Inotify presense does not change the semantics of C<ev_stat> watchers	1704	Inotify presence does not change the semantics of C<ev_stat> watchers
1644	except that changes might be detected earlier, and in some cases, to avoid	1705	except that changes might be detected earlier, and in some cases, to avoid
1645	making regular C<stat> calls. Even in the presense of inotify support	1706	making regular C<stat> calls. Even in the presence of inotify support
1646	there are many cases where libev has to resort to regular C<stat> polling.	1707	there are many cases where libev has to resort to regular C<stat> polling.
1647		1708
1648	(There is no support for kqueue, as apparently it cannot be used to	1709	(There is no support for kqueue, as apparently it cannot be used to
1649	implement this functionality, due to the requirement of having a file	1710	implement this functionality, due to the requirement of having a file
1650	descriptor open on the object at all times).	1711	descriptor open on the object at all times).
1651		1712
1652	=head3 The special problem of stat time resolution	1713	=head3 The special problem of stat time resolution
1653		1714
1654	The C<stat ()> syscall only supports full-second resolution portably, and	1715	The C<stat ()> system call only supports full-second resolution portably, and
1655	even on systems where the resolution is higher, many filesystems still	1716	even on systems where the resolution is higher, many file systems still
1656	only support whole seconds.	1717	only support whole seconds.
1657		1718
1658	That means that, if the time is the only thing that changes, you might	1719	That means that, if the time is the only thing that changes, you can
1659	miss updates: on the first update, C<ev_stat> detects a change and calls	1720	easily miss updates: on the first update, C<ev_stat> detects a change and
1660	your callback, which does something. When there is another update within	1721	calls your callback, which does something. When there is another update
1661	the same second, C<ev_stat> will be unable to detect it.	1722	within the same second, C<ev_stat> will be unable to detect it as the stat
		1723	data does not change.
1662		1724
1663	The solution to this is to delay acting on a change for a second (or till	1725	The solution to this is to delay acting on a change for slightly more
1664	the next second boundary), using a roughly one-second delay C<ev_timer>	1726	than a second (or till slightly after the next full second boundary), using
1665	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>	1727	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);
1666	is added to work around small timing inconsistencies of some operating	1728	ev_timer_again (loop, w)>).
1667	systems.	1729
		1730	The C<.02> offset is added to work around small timing inconsistencies
		1731	of some operating systems (where the second counter of the current time
		1732	might be be delayed. One such system is the Linux kernel, where a call to
		1733	C<gettimeofday> might return a timestamp with a full second later than
		1734	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1735	update file times then there will be a small window where the kernel uses
		1736	the previous second to update file times but libev might already execute
		1737	the timer callback).
1668		1738
1669	=head3 Watcher-Specific Functions and Data Members	1739	=head3 Watcher-Specific Functions and Data Members
1670		1740
1671	=over 4	1741	=over 4
1672		1742
…		…
1678	C<path>. The C<interval> is a hint on how quickly a change is expected to	1748	C<path>. The C<interval> is a hint on how quickly a change is expected to
1679	be detected and should normally be specified as C<0> to let libev choose	1749	be detected and should normally be specified as C<0> to let libev choose
1680	a suitable value. The memory pointed to by C<path> must point to the same	1750	a suitable value. The memory pointed to by C<path> must point to the same
1681	path for as long as the watcher is active.	1751	path for as long as the watcher is active.
1682		1752
1683	The callback will be receive C<EV_STAT> when a change was detected,	1753	The callback will receive C<EV_STAT> when a change was detected, relative
1684	relative to the attributes at the time the watcher was started (or the	1754	to the attributes at the time the watcher was started (or the last change
1685	last change was detected).	1755	was detected).
1686		1756
1687	=item ev_stat_stat (loop, ev_stat *)	1757	=item ev_stat_stat (loop, ev_stat *)
1688		1758
1689	Updates the stat buffer immediately with new values. If you change the	1759	Updates the stat buffer immediately with new values. If you change the
1690	watched path in your callback, you could call this fucntion to avoid	1760	watched path in your callback, you could call this function to avoid
1691	detecting this change (while introducing a race condition). Can also be	1761	detecting this change (while introducing a race condition if you are not
1692	useful simply to find out the new values.	1762	the only one changing the path). Can also be useful simply to find out the
		1763	new values.
1693		1764
1694	=item ev_statdata attr [read-only]	1765	=item ev_statdata attr [read-only]
1695		1766
1696	The most-recently detected attributes of the file. Although the type is of	1767	The most-recently detected attributes of the file. Although the type is
1697	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types	1768	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
1698	suitable for your system. If the C<st_nlink> member is C<0>, then there	1769	suitable for your system, but you can only rely on the POSIX-standardised
		1770	members to be present. If the C<st_nlink> member is C<0>, then there was
1699	was some error while C<stat>ing the file.	1771	some error while C<stat>ing the file.
1700		1772
1701	=item ev_statdata prev [read-only]	1773	=item ev_statdata prev [read-only]
1702		1774
1703	The previous attributes of the file. The callback gets invoked whenever	1775	The previous attributes of the file. The callback gets invoked whenever
1704	C<prev> != C<attr>.	1776	C<prev> != C<attr>, or, more precisely, one or more of these members
		1777	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1778	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1705		1779
1706	=item ev_tstamp interval [read-only]	1780	=item ev_tstamp interval [read-only]
1707		1781
1708	The specified interval.	1782	The specified interval.
1709		1783
1710	=item const char *path [read-only]	1784	=item const char *path [read-only]
1711		1785
1712	The filesystem path that is being watched.	1786	The file system path that is being watched.
1713		1787
1714	=back	1788	=back
1715		1789
1716	=head3 Examples	1790	=head3 Examples
1717		1791
1718	Example: Watch C</etc/passwd> for attribute changes.	1792	Example: Watch C</etc/passwd> for attribute changes.
1719		1793
1720	static void	1794	static void
1721	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1795	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1722	{	1796	{
1723	/* /etc/passwd changed in some way */	1797	/* /etc/passwd changed in some way */
1724	if (w->attr.st_nlink)	1798	if (w->attr.st_nlink)
1725	{	1799	{
1726	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1800	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1727	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1801	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1728	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1802	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1729	}	1803	}
1730	else	1804	else
1731	/* you shalt not abuse printf for puts */	1805	/* you shalt not abuse printf for puts */
1732	puts ("wow, /etc/passwd is not there, expect problems. "	1806	puts ("wow, /etc/passwd is not there, expect problems. "
1733	"if this is windows, they already arrived\n");	1807	"if this is windows, they already arrived\n");
1734	}	1808	}
1735		1809
1736	...	1810	...
1737	ev_stat passwd;	1811	ev_stat passwd;
1738		1812
1739	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1813	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1740	ev_stat_start (loop, &passwd);	1814	ev_stat_start (loop, &passwd);
1741		1815
1742	Example: Like above, but additionally use a one-second delay so we do not	1816	Example: Like above, but additionally use a one-second delay so we do not
1743	miss updates (however, frequent updates will delay processing, too, so	1817	miss updates (however, frequent updates will delay processing, too, so
1744	one might do the work both on C<ev_stat> callback invocation I<and> on	1818	one might do the work both on C<ev_stat> callback invocation I<and> on
1745	C<ev_timer> callback invocation).	1819	C<ev_timer> callback invocation).
1746		1820
1747	static ev_stat passwd;	1821	static ev_stat passwd;
1748	static ev_timer timer;	1822	static ev_timer timer;
1749		1823
1750	static void	1824	static void
1751	timer_cb (EV_P_ ev_timer *w, int revents)	1825	timer_cb (EV_P_ ev_timer *w, int revents)
1752	{	1826	{
1753	ev_timer_stop (EV_A_ w);	1827	ev_timer_stop (EV_A_ w);
1754		1828
1755	/* now it's one second after the most recent passwd change */	1829	/* now it's one second after the most recent passwd change */
1756	}	1830	}
1757		1831
1758	static void	1832	static void
1759	stat_cb (EV_P_ ev_stat *w, int revents)	1833	stat_cb (EV_P_ ev_stat *w, int revents)
1760	{	1834	{
1761	/* reset the one-second timer */	1835	/* reset the one-second timer */
1762	ev_timer_again (EV_A_ &timer);	1836	ev_timer_again (EV_A_ &timer);
1763	}	1837	}
1764		1838
1765	...	1839	...
1766	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1840	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1767	ev_stat_start (loop, &passwd);	1841	ev_stat_start (loop, &passwd);
1768	ev_timer_init (&timer, timer_cb, 0., 1.01);	1842	ev_timer_init (&timer, timer_cb, 0., 1.02);
1769		1843
1770		1844
1771	=head2 C<ev_idle> - when you've got nothing better to do...	1845	=head2 C<ev_idle> - when you've got nothing better to do...
1772		1846
1773	Idle watchers trigger events when no other events of the same or higher	1847	Idle watchers trigger events when no other events of the same or higher
…		…
1804	=head3 Examples	1878	=head3 Examples
1805		1879
1806	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1880	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1807	callback, free it. Also, use no error checking, as usual.	1881	callback, free it. Also, use no error checking, as usual.
1808		1882
1809	static void	1883	static void
1810	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1884	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1811	{	1885	{
1812	free (w);	1886	free (w);
1813	// now do something you wanted to do when the program has	1887	// now do something you wanted to do when the program has
1814	// no longer anything immediate to do.	1888	// no longer anything immediate to do.
1815	}	1889	}
1816		1890
1817	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1891	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1818	ev_idle_init (idle_watcher, idle_cb);	1892	ev_idle_init (idle_watcher, idle_cb);
1819	ev_idle_start (loop, idle_cb);	1893	ev_idle_start (loop, idle_cb);
1820		1894
1821		1895
1822	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1896	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1823		1897
1824	Prepare and check watchers are usually (but not always) used in tandem:	1898	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1843		1917
1844	This is done by examining in each prepare call which file descriptors need	1918	This is done by examining in each prepare call which file descriptors need
1845	to be watched by the other library, registering C<ev_io> watchers for	1919	to be watched by the other library, registering C<ev_io> watchers for
1846	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1920	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1847	provide just this functionality). Then, in the check watcher you check for	1921	provide just this functionality). Then, in the check watcher you check for
1848	any events that occured (by checking the pending status of all watchers	1922	any events that occurred (by checking the pending status of all watchers
1849	and stopping them) and call back into the library. The I/O and timer	1923	and stopping them) and call back into the library. The I/O and timer
1850	callbacks will never actually be called (but must be valid nevertheless,	1924	callbacks will never actually be called (but must be valid nevertheless,
1851	because you never know, you know?).	1925	because you never know, you know?).
1852		1926
1853	As another example, the Perl Coro module uses these hooks to integrate	1927	As another example, the Perl Coro module uses these hooks to integrate
…		…
1861		1935
1862	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1936	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
1863	priority, to ensure that they are being run before any other watchers	1937	priority, to ensure that they are being run before any other watchers
1864	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,	1938	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
1865	too) should not activate ("feed") events into libev. While libev fully	1939	too) should not activate ("feed") events into libev. While libev fully
1866	supports this, they will be called before other C<ev_check> watchers	1940	supports this, they might get executed before other C<ev_check> watchers
1867	did their job. As C<ev_check> watchers are often used to embed other	1941	did their job. As C<ev_check> watchers are often used to embed other
1868	(non-libev) event loops those other event loops might be in an unusable	1942	(non-libev) event loops those other event loops might be in an unusable
1869	state until their C<ev_check> watcher ran (always remind yourself to	1943	state until their C<ev_check> watcher ran (always remind yourself to
1870	coexist peacefully with others).	1944	coexist peacefully with others).
1871		1945
…		…
1886	=head3 Examples	1960	=head3 Examples
1887		1961
1888	There are a number of principal ways to embed other event loops or modules	1962	There are a number of principal ways to embed other event loops or modules
1889	into libev. Here are some ideas on how to include libadns into libev	1963	into libev. Here are some ideas on how to include libadns into libev
1890	(there is a Perl module named C<EV::ADNS> that does this, which you could	1964	(there is a Perl module named C<EV::ADNS> that does this, which you could
1891	use for an actually working example. Another Perl module named C<EV::Glib>	1965	use as a working example. Another Perl module named C<EV::Glib> embeds a
1892	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV	1966	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1893	into the Glib event loop).	1967	Glib event loop).
1894		1968
1895	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	1969	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1896	and in a check watcher, destroy them and call into libadns. What follows	1970	and in a check watcher, destroy them and call into libadns. What follows
1897	is pseudo-code only of course. This requires you to either use a low	1971	is pseudo-code only of course. This requires you to either use a low
1898	priority for the check watcher or use C<ev_clear_pending> explicitly, as	1972	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1899	the callbacks for the IO/timeout watchers might not have been called yet.	1973	the callbacks for the IO/timeout watchers might not have been called yet.
1900		1974
1901	static ev_io iow [nfd];	1975	static ev_io iow [nfd];
1902	static ev_timer tw;	1976	static ev_timer tw;
1903		1977
1904	static void	1978	static void
1905	io_cb (ev_loop *loop, ev_io *w, int revents)	1979	io_cb (ev_loop *loop, ev_io *w, int revents)
1906	{	1980	{
1907	}	1981	}
1908		1982
1909	// create io watchers for each fd and a timer before blocking	1983	// create io watchers for each fd and a timer before blocking
1910	static void	1984	static void
1911	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1985	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1912	{	1986	{
1913	int timeout = 3600000;	1987	int timeout = 3600000;
1914	struct pollfd fds [nfd];	1988	struct pollfd fds [nfd];
1915	// actual code will need to loop here and realloc etc.	1989	// actual code will need to loop here and realloc etc.
1916	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1990	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1917		1991
1918	/* the callback is illegal, but won't be called as we stop during check */	1992	/* the callback is illegal, but won't be called as we stop during check */
1919	ev_timer_init (&tw, 0, timeout * 1e-3);	1993	ev_timer_init (&tw, 0, timeout * 1e-3);
1920	ev_timer_start (loop, &tw);	1994	ev_timer_start (loop, &tw);
1921		1995
1922	// create one ev_io per pollfd	1996	// create one ev_io per pollfd
1923	for (int i = 0; i < nfd; ++i)	1997	for (int i = 0; i < nfd; ++i)
1924	{	1998	{
1925	ev_io_init (iow + i, io_cb, fds [i].fd,	1999	ev_io_init (iow + i, io_cb, fds [i].fd,
1926	((fds [i].events & POLLIN ? EV_READ : 0)	2000	((fds [i].events & POLLIN ? EV_READ : 0)
1927	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	2001	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1928		2002
1929	fds [i].revents = 0;	2003	fds [i].revents = 0;
1930	ev_io_start (loop, iow + i);	2004	ev_io_start (loop, iow + i);
1931	}	2005	}
1932	}	2006	}
1933		2007
1934	// stop all watchers after blocking	2008	// stop all watchers after blocking
1935	static void	2009	static void
1936	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	2010	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1937	{	2011	{
1938	ev_timer_stop (loop, &tw);	2012	ev_timer_stop (loop, &tw);
1939		2013
1940	for (int i = 0; i < nfd; ++i)	2014	for (int i = 0; i < nfd; ++i)
1941	{	2015	{
1942	// set the relevant poll flags	2016	// set the relevant poll flags
1943	// could also call adns_processreadable etc. here	2017	// could also call adns_processreadable etc. here
1944	struct pollfd *fd = fds + i;	2018	struct pollfd *fd = fds + i;
1945	int revents = ev_clear_pending (iow + i);	2019	int revents = ev_clear_pending (iow + i);
1946	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	2020	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1947	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	2021	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1948		2022
1949	// now stop the watcher	2023	// now stop the watcher
1950	ev_io_stop (loop, iow + i);	2024	ev_io_stop (loop, iow + i);
1951	}	2025	}
1952		2026
1953	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2027	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1954	}	2028	}
1955		2029
1956	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2030	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
1957	in the prepare watcher and would dispose of the check watcher.	2031	in the prepare watcher and would dispose of the check watcher.
1958		2032
1959	Method 3: If the module to be embedded supports explicit event	2033	Method 3: If the module to be embedded supports explicit event
1960	notification (adns does), you can also make use of the actual watcher	2034	notification (libadns does), you can also make use of the actual watcher
1961	callbacks, and only destroy/create the watchers in the prepare watcher.	2035	callbacks, and only destroy/create the watchers in the prepare watcher.
1962		2036
1963	static void	2037	static void
1964	timer_cb (EV_P_ ev_timer *w, int revents)	2038	timer_cb (EV_P_ ev_timer *w, int revents)
1965	{	2039	{
1966	adns_state ads = (adns_state)w->data;	2040	adns_state ads = (adns_state)w->data;
1967	update_now (EV_A);	2041	update_now (EV_A);
1968		2042
1969	adns_processtimeouts (ads, &tv_now);	2043	adns_processtimeouts (ads, &tv_now);
1970	}	2044	}
1971		2045
1972	static void	2046	static void
1973	io_cb (EV_P_ ev_io *w, int revents)	2047	io_cb (EV_P_ ev_io *w, int revents)
1974	{	2048	{
1975	adns_state ads = (adns_state)w->data;	2049	adns_state ads = (adns_state)w->data;
1976	update_now (EV_A);	2050	update_now (EV_A);
1977		2051
1978	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2052	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1979	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2053	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1980	}	2054	}
1981		2055
1982	// do not ever call adns_afterpoll	2056	// do not ever call adns_afterpoll
1983		2057
1984	Method 4: Do not use a prepare or check watcher because the module you	2058	Method 4: Do not use a prepare or check watcher because the module you
1985	want to embed is too inflexible to support it. Instead, youc na override	2059	want to embed is too inflexible to support it. Instead, you can override
1986	their poll function. The drawback with this solution is that the main	2060	their poll function. The drawback with this solution is that the main
1987	loop is now no longer controllable by EV. The C<Glib::EV> module does	2061	loop is now no longer controllable by EV. The C<Glib::EV> module does
1988	this.	2062	this.
1989		2063
1990	static gint	2064	static gint
1991	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2065	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1992	{	2066	{
1993	int got_events = 0;	2067	int got_events = 0;
1994		2068
1995	for (n = 0; n < nfds; ++n)	2069	for (n = 0; n < nfds; ++n)
1996	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2070	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1997		2071
1998	if (timeout >= 0)	2072	if (timeout >= 0)
1999	// create/start timer	2073	// create/start timer
2000		2074
2001	// poll	2075	// poll
2002	ev_loop (EV_A_ 0);	2076	ev_loop (EV_A_ 0);
2003		2077
2004	// stop timer again	2078	// stop timer again
2005	if (timeout >= 0)	2079	if (timeout >= 0)
2006	ev_timer_stop (EV_A_ &to);	2080	ev_timer_stop (EV_A_ &to);
2007		2081
2008	// stop io watchers again - their callbacks should have set	2082	// stop io watchers again - their callbacks should have set
2009	for (n = 0; n < nfds; ++n)	2083	for (n = 0; n < nfds; ++n)
2010	ev_io_stop (EV_A_ iow [n]);	2084	ev_io_stop (EV_A_ iow [n]);
2011		2085
2012	return got_events;	2086	return got_events;
2013	}	2087	}
2014		2088
2015		2089
2016	=head2 C<ev_embed> - when one backend isn't enough...	2090	=head2 C<ev_embed> - when one backend isn't enough...
2017		2091
2018	This is a rather advanced watcher type that lets you embed one event loop	2092	This is a rather advanced watcher type that lets you embed one event loop
…		…
2074		2148
2075	Configures the watcher to embed the given loop, which must be	2149	Configures the watcher to embed the given loop, which must be
2076	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be	2150	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
2077	invoked automatically, otherwise it is the responsibility of the callback	2151	invoked automatically, otherwise it is the responsibility of the callback
2078	to invoke it (it will continue to be called until the sweep has been done,	2152	to invoke it (it will continue to be called until the sweep has been done,
2079	if you do not want thta, you need to temporarily stop the embed watcher).	2153	if you do not want that, you need to temporarily stop the embed watcher).
2080		2154
2081	=item ev_embed_sweep (loop, ev_embed *)	2155	=item ev_embed_sweep (loop, ev_embed *)
2082		2156
2083	Make a single, non-blocking sweep over the embedded loop. This works	2157	Make a single, non-blocking sweep over the embedded loop. This works
2084	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2158	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2085	apropriate way for embedded loops.	2159	appropriate way for embedded loops.
2086		2160
2087	=item struct ev_loop *other [read-only]	2161	=item struct ev_loop *other [read-only]
2088		2162
2089	The embedded event loop.	2163	The embedded event loop.
2090		2164
…		…
2092		2166
2093	=head3 Examples	2167	=head3 Examples
2094		2168
2095	Example: Try to get an embeddable event loop and embed it into the default	2169	Example: Try to get an embeddable event loop and embed it into the default
2096	event loop. If that is not possible, use the default loop. The default	2170	event loop. If that is not possible, use the default loop. The default
2097	loop is stored in C<loop_hi>, while the mebeddable loop is stored in	2171	loop is stored in C<loop_hi>, while the embeddable loop is stored in
2098	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be	2172	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2099	used).	2173	used).
2100		2174
2101	struct ev_loop *loop_hi = ev_default_init (0);	2175	struct ev_loop *loop_hi = ev_default_init (0);
2102	struct ev_loop *loop_lo = 0;	2176	struct ev_loop *loop_lo = 0;
2103	struct ev_embed embed;	2177	struct ev_embed embed;
2104		2178
2105	// see if there is a chance of getting one that works	2179	// see if there is a chance of getting one that works
2106	// (remember that a flags value of 0 means autodetection)	2180	// (remember that a flags value of 0 means autodetection)
2107	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2181	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2108	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2182	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2109	: 0;	2183	: 0;
2110		2184
2111	// if we got one, then embed it, otherwise default to loop_hi	2185	// if we got one, then embed it, otherwise default to loop_hi
2112	if (loop_lo)	2186	if (loop_lo)
2113	{	2187	{
2114	ev_embed_init (&embed, 0, loop_lo);	2188	ev_embed_init (&embed, 0, loop_lo);
2115	ev_embed_start (loop_hi, &embed);	2189	ev_embed_start (loop_hi, &embed);
2116	}	2190	}
2117	else	2191	else
2118	loop_lo = loop_hi;	2192	loop_lo = loop_hi;
2119		2193
2120	Example: Check if kqueue is available but not recommended and create	2194	Example: Check if kqueue is available but not recommended and create
2121	a kqueue backend for use with sockets (which usually work with any	2195	a kqueue backend for use with sockets (which usually work with any
2122	kqueue implementation). Store the kqueue/socket-only event loop in	2196	kqueue implementation). Store the kqueue/socket-only event loop in
2123	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2197	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2124		2198
2125	struct ev_loop *loop = ev_default_init (0);	2199	struct ev_loop *loop = ev_default_init (0);
2126	struct ev_loop *loop_socket = 0;	2200	struct ev_loop *loop_socket = 0;
2127	struct ev_embed embed;	2201	struct ev_embed embed;
2128		2202
2129	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2203	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2130	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2204	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2131	{	2205	{
2132	ev_embed_init (&embed, 0, loop_socket);	2206	ev_embed_init (&embed, 0, loop_socket);
2133	ev_embed_start (loop, &embed);	2207	ev_embed_start (loop, &embed);
2134	}	2208	}
2135		2209
2136	if (!loop_socket)	2210	if (!loop_socket)
2137	loop_socket = loop;	2211	loop_socket = loop;
2138		2212
2139	// now use loop_socket for all sockets, and loop for everything else	2213	// now use loop_socket for all sockets, and loop for everything else
2140		2214
2141		2215
2142	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2216	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2143		2217
2144	Fork watchers are called when a C<fork ()> was detected (usually because	2218	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2197		2271
2198	=item queueing from a signal handler context	2272	=item queueing from a signal handler context
2199		2273
2200	To implement race-free queueing, you simply add to the queue in the signal	2274	To implement race-free queueing, you simply add to the queue in the signal
2201	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2275	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2202	some fictitiuous SIGUSR1 handler:	2276	some fictitious SIGUSR1 handler:
2203		2277
2204	static ev_async mysig;	2278	static ev_async mysig;
2205		2279
2206	static void	2280	static void
2207	sigusr1_handler (void)	2281	sigusr1_handler (void)
…		…
2281	=item ev_async_send (loop, ev_async *)	2355	=item ev_async_send (loop, ev_async *)
2282		2356
2283	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2357	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2284	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2358	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2285	C<ev_feed_event>, this call is safe to do in other threads, signal or	2359	C<ev_feed_event>, this call is safe to do in other threads, signal or
2286	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding	2360	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2287	section below on what exactly this means).	2361	section below on what exactly this means).
2288		2362
2289	This call incurs the overhead of a syscall only once per loop iteration,	2363	This call incurs the overhead of a system call only once per loop iteration,
2290	so while the overhead might be noticable, it doesn't apply to repeated	2364	so while the overhead might be noticeable, it doesn't apply to repeated
2291	calls to C<ev_async_send>.	2365	calls to C<ev_async_send>.
2292		2366
2293	=item bool = ev_async_pending (ev_async *)	2367	=item bool = ev_async_pending (ev_async *)
2294		2368
2295	Returns a non-zero value when C<ev_async_send> has been called on the	2369	Returns a non-zero value when C<ev_async_send> has been called on the
…		…
2297	event loop.	2371	event loop.
2298		2372
2299	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When	2373	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
2300	the loop iterates next and checks for the watcher to have become active,	2374	the loop iterates next and checks for the watcher to have become active,
2301	it will reset the flag again. C<ev_async_pending> can be used to very	2375	it will reset the flag again. C<ev_async_pending> can be used to very
2302	quickly check wether invoking the loop might be a good idea.	2376	quickly check whether invoking the loop might be a good idea.
2303		2377
2304	Not that this does I<not> check wether the watcher itself is pending, only	2378	Not that this does I<not> check whether the watcher itself is pending, only
2305	wether it has been requested to make this watcher pending.	2379	whether it has been requested to make this watcher pending.
2306		2380
2307	=back	2381	=back
2308		2382
2309		2383
2310	=head1 OTHER FUNCTIONS	2384	=head1 OTHER FUNCTIONS
…		…
2321	or timeout without having to allocate/configure/start/stop/free one or	2395	or timeout without having to allocate/configure/start/stop/free one or
2322	more watchers yourself.	2396	more watchers yourself.
2323		2397
2324	If C<fd> is less than 0, then no I/O watcher will be started and events	2398	If C<fd> is less than 0, then no I/O watcher will be started and events
2325	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2399	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2326	C<events> set will be craeted and started.	2400	C<events> set will be created and started.
2327		2401
2328	If C<timeout> is less than 0, then no timeout watcher will be	2402	If C<timeout> is less than 0, then no timeout watcher will be
2329	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2403	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2330	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2404	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2331	dubious value.	2405	dubious value.
…		…
2333	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2407	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2334	passed an C<revents> set like normal event callbacks (a combination of	2408	passed an C<revents> set like normal event callbacks (a combination of
2335	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2409	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2336	value passed to C<ev_once>:	2410	value passed to C<ev_once>:
2337		2411
2338	static void stdin_ready (int revents, void *arg)	2412	static void stdin_ready (int revents, void *arg)
2339	{	2413	{
2340	if (revents & EV_TIMEOUT)	2414	if (revents & EV_TIMEOUT)
2341	/* doh, nothing entered */;	2415	/* doh, nothing entered */;
2342	else if (revents & EV_READ)	2416	else if (revents & EV_READ)
2343	/* stdin might have data for us, joy! */;	2417	/* stdin might have data for us, joy! */;
2344	}	2418	}
2345		2419
2346	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2420	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2347		2421
2348	=item ev_feed_event (ev_loop *, watcher *, int revents)	2422	=item ev_feed_event (ev_loop *, watcher *, int revents)
2349		2423
2350	Feeds the given event set into the event loop, as if the specified event	2424	Feeds the given event set into the event loop, as if the specified event
2351	had happened for the specified watcher (which must be a pointer to an	2425	had happened for the specified watcher (which must be a pointer to an
…		…
2356	Feed an event on the given fd, as if a file descriptor backend detected	2430	Feed an event on the given fd, as if a file descriptor backend detected
2357	the given events it.	2431	the given events it.
2358		2432
2359	=item ev_feed_signal_event (ev_loop *loop, int signum)	2433	=item ev_feed_signal_event (ev_loop *loop, int signum)
2360		2434
2361	Feed an event as if the given signal occured (C<loop> must be the default	2435	Feed an event as if the given signal occurred (C<loop> must be the default
2362	loop!).	2436	loop!).
2363		2437
2364	=back	2438	=back
2365		2439
2366		2440
…		…
2382		2456
2383	=item * Priorities are not currently supported. Initialising priorities	2457	=item * Priorities are not currently supported. Initialising priorities
2384	will fail and all watchers will have the same priority, even though there	2458	will fail and all watchers will have the same priority, even though there
2385	is an ev_pri field.	2459	is an ev_pri field.
2386		2460
		2461	=item * In libevent, the last base created gets the signals, in libev, the
		2462	first base created (== the default loop) gets the signals.
		2463
2387	=item * Other members are not supported.	2464	=item * Other members are not supported.
2388		2465
2389	=item * The libev emulation is I<not> ABI compatible to libevent, you need	2466	=item * The libev emulation is I<not> ABI compatible to libevent, you need
2390	to use the libev header file and library.	2467	to use the libev header file and library.
2391		2468
2392	=back	2469	=back
2393		2470
2394	=head1 C++ SUPPORT	2471	=head1 C++ SUPPORT
2395		2472
2396	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2473	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2397	you to use some convinience methods to start/stop watchers and also change	2474	you to use some convenience methods to start/stop watchers and also change
2398	the callback model to a model using method callbacks on objects.	2475	the callback model to a model using method callbacks on objects.
2399		2476
2400	To use it,	2477	To use it,
2401		2478
2402	#include <ev++.h>	2479	#include <ev++.h>
2403		2480
2404	This automatically includes F<ev.h> and puts all of its definitions (many	2481	This automatically includes F<ev.h> and puts all of its definitions (many
2405	of them macros) into the global namespace. All C++ specific things are	2482	of them macros) into the global namespace. All C++ specific things are
2406	put into the C<ev> namespace. It should support all the same embedding	2483	put into the C<ev> namespace. It should support all the same embedding
2407	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2484	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2474	your compiler is good :), then the method will be fully inlined into the	2551	your compiler is good :), then the method will be fully inlined into the
2475	thunking function, making it as fast as a direct C callback.	2552	thunking function, making it as fast as a direct C callback.
2476		2553
2477	Example: simple class declaration and watcher initialisation	2554	Example: simple class declaration and watcher initialisation
2478		2555
2479	struct myclass	2556	struct myclass
2480	{	2557	{
2481	void io_cb (ev::io &w, int revents) { }	2558	void io_cb (ev::io &w, int revents) { }
2482	}	2559	}
2483		2560
2484	myclass obj;	2561	myclass obj;
2485	ev::io iow;	2562	ev::io iow;
2486	iow.set <myclass, &myclass::io_cb> (&obj);	2563	iow.set <myclass, &myclass::io_cb> (&obj);
2487		2564
2488	=item w->set<function> (void *data = 0)	2565	=item w->set<function> (void *data = 0)
2489		2566
2490	Also sets a callback, but uses a static method or plain function as	2567	Also sets a callback, but uses a static method or plain function as
2491	callback. The optional C<data> argument will be stored in the watcher's	2568	callback. The optional C<data> argument will be stored in the watcher's
…		…
2495		2572
2496	See the method-C<set> above for more details.	2573	See the method-C<set> above for more details.
2497		2574
2498	Example:	2575	Example:
2499		2576
2500	static void io_cb (ev::io &w, int revents) { }	2577	static void io_cb (ev::io &w, int revents) { }
2501	iow.set <io_cb> ();	2578	iow.set <io_cb> ();
2502		2579
2503	=item w->set (struct ev_loop *)	2580	=item w->set (struct ev_loop *)
2504		2581
2505	Associates a different C<struct ev_loop> with this watcher. You can only	2582	Associates a different C<struct ev_loop> with this watcher. You can only
2506	do this when the watcher is inactive (and not pending either).	2583	do this when the watcher is inactive (and not pending either).
2507		2584
2508	=item w->set ([args])	2585	=item w->set ([arguments])
2509		2586
2510	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2587	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2511	called at least once. Unlike the C counterpart, an active watcher gets	2588	called at least once. Unlike the C counterpart, an active watcher gets
2512	automatically stopped and restarted when reconfiguring it with this	2589	automatically stopped and restarted when reconfiguring it with this
2513	method.	2590	method.
2514		2591
2515	=item w->start ()	2592	=item w->start ()
…		…
2539	=back	2616	=back
2540		2617
2541	Example: Define a class with an IO and idle watcher, start one of them in	2618	Example: Define a class with an IO and idle watcher, start one of them in
2542	the constructor.	2619	the constructor.
2543		2620
2544	class myclass	2621	class myclass
2545	{	2622	{
2546	ev::io io; void io_cb (ev::io &w, int revents);	2623	ev::io io; void io_cb (ev::io &w, int revents);
2547	ev:idle idle void idle_cb (ev::idle &w, int revents);	2624	ev:idle idle void idle_cb (ev::idle &w, int revents);
2548		2625
2549	myclass (int fd)	2626	myclass (int fd)
2550	{	2627	{
2551	io .set <myclass, &myclass::io_cb > (this);	2628	io .set <myclass, &myclass::io_cb > (this);
2552	idle.set <myclass, &myclass::idle_cb> (this);	2629	idle.set <myclass, &myclass::idle_cb> (this);
2553		2630
2554	io.start (fd, ev::READ);	2631	io.start (fd, ev::READ);
2555	}	2632	}
2556	};	2633	};
2557		2634
2558		2635
2559	=head1 OTHER LANGUAGE BINDINGS	2636	=head1 OTHER LANGUAGE BINDINGS
2560		2637
2561	Libev does not offer other language bindings itself, but bindings for a	2638	Libev does not offer other language bindings itself, but bindings for a
2562	numbe rof languages exist in the form of third-party packages. If you know	2639	number of languages exist in the form of third-party packages. If you know
2563	any interesting language binding in addition to the ones listed here, drop	2640	any interesting language binding in addition to the ones listed here, drop
2564	me a note.	2641	me a note.
2565		2642
2566	=over 4	2643	=over 4
2567		2644
…		…
2571	libev. EV is developed together with libev. Apart from the EV core module,	2648	libev. EV is developed together with libev. Apart from the EV core module,
2572	there are additional modules that implement libev-compatible interfaces	2649	there are additional modules that implement libev-compatible interfaces
2573	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the	2650	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
2574	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).	2651	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2575		2652
2576	It can be found and installed via CPAN, its homepage is found at	2653	It can be found and installed via CPAN, its homepage is at
2577	L<http://software.schmorp.de/pkg/EV>.	2654	L<http://software.schmorp.de/pkg/EV>.
2578		2655
		2656	=item Python
		2657
		2658	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2659	seems to be quite complete and well-documented. Note, however, that the
		2660	patch they require for libev is outright dangerous as it breaks the ABI
		2661	for everybody else, and therefore, should never be applied in an installed
		2662	libev (if python requires an incompatible ABI then it needs to embed
		2663	libev).
		2664
2579	=item Ruby	2665	=item Ruby
2580		2666
2581	Tony Arcieri has written a ruby extension that offers access to a subset	2667	Tony Arcieri has written a ruby extension that offers access to a subset
2582	of the libev API and adds filehandle abstractions, asynchronous DNS and	2668	of the libev API and adds file handle abstractions, asynchronous DNS and
2583	more on top of it. It can be found via gem servers. Its homepage is at	2669	more on top of it. It can be found via gem servers. Its homepage is at
2584	L<http://rev.rubyforge.org/>.	2670	L<http://rev.rubyforge.org/>.
2585		2671
2586	=item D	2672	=item D
2587		2673
2588	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	2674	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
2589	be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.	2675	be found at L<http://proj.llucax.com.ar/wiki/evd>.
2590		2676
2591	=back	2677	=back
2592		2678
2593		2679
2594	=head1 MACRO MAGIC	2680	=head1 MACRO MAGIC
2595		2681
2596	Libev can be compiled with a variety of options, the most fundamantal	2682	Libev can be compiled with a variety of options, the most fundamental
2597	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2683	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2598	functions and callbacks have an initial C<struct ev_loop *> argument.	2684	functions and callbacks have an initial C<struct ev_loop *> argument.
2599		2685
2600	To make it easier to write programs that cope with either variant, the	2686	To make it easier to write programs that cope with either variant, the
2601	following macros are defined:	2687	following macros are defined:
…		…
2606		2692
2607	This provides the loop I<argument> for functions, if one is required ("ev	2693	This provides the loop I<argument> for functions, if one is required ("ev
2608	loop argument"). The C<EV_A> form is used when this is the sole argument,	2694	loop argument"). The C<EV_A> form is used when this is the sole argument,
2609	C<EV_A_> is used when other arguments are following. Example:	2695	C<EV_A_> is used when other arguments are following. Example:
2610		2696
2611	ev_unref (EV_A);	2697	ev_unref (EV_A);
2612	ev_timer_add (EV_A_ watcher);	2698	ev_timer_add (EV_A_ watcher);
2613	ev_loop (EV_A_ 0);	2699	ev_loop (EV_A_ 0);
2614		2700
2615	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2701	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2616	which is often provided by the following macro.	2702	which is often provided by the following macro.
2617		2703
2618	=item C<EV_P>, C<EV_P_>	2704	=item C<EV_P>, C<EV_P_>
2619		2705
2620	This provides the loop I<parameter> for functions, if one is required ("ev	2706	This provides the loop I<parameter> for functions, if one is required ("ev
2621	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2707	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2622	C<EV_P_> is used when other parameters are following. Example:	2708	C<EV_P_> is used when other parameters are following. Example:
2623		2709
2624	// this is how ev_unref is being declared	2710	// this is how ev_unref is being declared
2625	static void ev_unref (EV_P);	2711	static void ev_unref (EV_P);
2626		2712
2627	// this is how you can declare your typical callback	2713	// this is how you can declare your typical callback
2628	static void cb (EV_P_ ev_timer *w, int revents)	2714	static void cb (EV_P_ ev_timer *w, int revents)
2629		2715
2630	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2716	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2631	suitable for use with C<EV_A>.	2717	suitable for use with C<EV_A>.
2632		2718
2633	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2719	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
2634		2720
2635	Similar to the other two macros, this gives you the value of the default	2721	Similar to the other two macros, this gives you the value of the default
2636	loop, if multiple loops are supported ("ev loop default").	2722	loop, if multiple loops are supported ("ev loop default").
		2723
		2724	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
		2725
		2726	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
		2727	default loop has been initialised (C<UC> == unchecked). Their behaviour
		2728	is undefined when the default loop has not been initialised by a previous
		2729	execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
		2730
		2731	It is often prudent to use C<EV_DEFAULT> when initialising the first
		2732	watcher in a function but use C<EV_DEFAULT_UC> afterwards.
2637		2733
2638	=back	2734	=back
2639		2735
2640	Example: Declare and initialise a check watcher, utilising the above	2736	Example: Declare and initialise a check watcher, utilising the above
2641	macros so it will work regardless of whether multiple loops are supported	2737	macros so it will work regardless of whether multiple loops are supported
2642	or not.	2738	or not.
2643		2739
2644	static void	2740	static void
2645	check_cb (EV_P_ ev_timer *w, int revents)	2741	check_cb (EV_P_ ev_timer *w, int revents)
2646	{	2742	{
2647	ev_check_stop (EV_A_ w);	2743	ev_check_stop (EV_A_ w);
2648	}	2744	}
2649		2745
2650	ev_check check;	2746	ev_check check;
2651	ev_check_init (&check, check_cb);	2747	ev_check_init (&check, check_cb);
2652	ev_check_start (EV_DEFAULT_ &check);	2748	ev_check_start (EV_DEFAULT_ &check);
2653	ev_loop (EV_DEFAULT_ 0);	2749	ev_loop (EV_DEFAULT_ 0);
2654		2750
2655	=head1 EMBEDDING	2751	=head1 EMBEDDING
2656		2752
2657	Libev can (and often is) directly embedded into host	2753	Libev can (and often is) directly embedded into host
2658	applications. Examples of applications that embed it include the Deliantra	2754	applications. Examples of applications that embed it include the Deliantra
…		…
2665	libev somewhere in your source tree).	2761	libev somewhere in your source tree).
2666		2762
2667	=head2 FILESETS	2763	=head2 FILESETS
2668		2764
2669	Depending on what features you need you need to include one or more sets of files	2765	Depending on what features you need you need to include one or more sets of files
2670	in your app.	2766	in your application.
2671		2767
2672	=head3 CORE EVENT LOOP	2768	=head3 CORE EVENT LOOP
2673		2769
2674	To include only the libev core (all the C<ev_*> functions), with manual	2770	To include only the libev core (all the C<ev_*> functions), with manual
2675	configuration (no autoconf):	2771	configuration (no autoconf):
2676		2772
2677	#define EV_STANDALONE 1	2773	#define EV_STANDALONE 1
2678	#include "ev.c"	2774	#include "ev.c"
2679		2775
2680	This will automatically include F<ev.h>, too, and should be done in a	2776	This will automatically include F<ev.h>, too, and should be done in a
2681	single C source file only to provide the function implementations. To use	2777	single C source file only to provide the function implementations. To use
2682	it, do the same for F<ev.h> in all files wishing to use this API (best	2778	it, do the same for F<ev.h> in all files wishing to use this API (best
2683	done by writing a wrapper around F<ev.h> that you can include instead and	2779	done by writing a wrapper around F<ev.h> that you can include instead and
2684	where you can put other configuration options):	2780	where you can put other configuration options):
2685		2781
2686	#define EV_STANDALONE 1	2782	#define EV_STANDALONE 1
2687	#include "ev.h"	2783	#include "ev.h"
2688		2784
2689	Both header files and implementation files can be compiled with a C++	2785	Both header files and implementation files can be compiled with a C++
2690	compiler (at least, thats a stated goal, and breakage will be treated	2786	compiler (at least, thats a stated goal, and breakage will be treated
2691	as a bug).	2787	as a bug).
2692		2788
2693	You need the following files in your source tree, or in a directory	2789	You need the following files in your source tree, or in a directory
2694	in your include path (e.g. in libev/ when using -Ilibev):	2790	in your include path (e.g. in libev/ when using -Ilibev):
2695		2791
2696	ev.h	2792	ev.h
2697	ev.c	2793	ev.c
2698	ev_vars.h	2794	ev_vars.h
2699	ev_wrap.h	2795	ev_wrap.h
2700		2796
2701	ev_win32.c required on win32 platforms only	2797	ev_win32.c required on win32 platforms only
2702		2798
2703	ev_select.c only when select backend is enabled (which is enabled by default)	2799	ev_select.c only when select backend is enabled (which is enabled by default)
2704	ev_poll.c only when poll backend is enabled (disabled by default)	2800	ev_poll.c only when poll backend is enabled (disabled by default)
2705	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2801	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2706	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2802	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2707	ev_port.c only when the solaris port backend is enabled (disabled by default)	2803	ev_port.c only when the solaris port backend is enabled (disabled by default)
2708		2804
2709	F<ev.c> includes the backend files directly when enabled, so you only need	2805	F<ev.c> includes the backend files directly when enabled, so you only need
2710	to compile this single file.	2806	to compile this single file.
2711		2807
2712	=head3 LIBEVENT COMPATIBILITY API	2808	=head3 LIBEVENT COMPATIBILITY API
2713		2809
2714	To include the libevent compatibility API, also include:	2810	To include the libevent compatibility API, also include:
2715		2811
2716	#include "event.c"	2812	#include "event.c"
2717		2813
2718	in the file including F<ev.c>, and:	2814	in the file including F<ev.c>, and:
2719		2815
2720	#include "event.h"	2816	#include "event.h"
2721		2817
2722	in the files that want to use the libevent API. This also includes F<ev.h>.	2818	in the files that want to use the libevent API. This also includes F<ev.h>.
2723		2819
2724	You need the following additional files for this:	2820	You need the following additional files for this:
2725		2821
2726	event.h	2822	event.h
2727	event.c	2823	event.c
2728		2824
2729	=head3 AUTOCONF SUPPORT	2825	=head3 AUTOCONF SUPPORT
2730		2826
2731	Instead of using C<EV_STANDALONE=1> and providing your config in	2827	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2732	whatever way you want, you can also C<m4_include([libev.m4])> in your	2828	whatever way you want, you can also C<m4_include([libev.m4])> in your
2733	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2829	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2734	include F<config.h> and configure itself accordingly.	2830	include F<config.h> and configure itself accordingly.
2735		2831
2736	For this of course you need the m4 file:	2832	For this of course you need the m4 file:
2737		2833
2738	libev.m4	2834	libev.m4
2739		2835
2740	=head2 PREPROCESSOR SYMBOLS/MACROS	2836	=head2 PREPROCESSOR SYMBOLS/MACROS
2741		2837
2742	Libev can be configured via a variety of preprocessor symbols you have to	2838	Libev can be configured via a variety of preprocessor symbols you have to
2743	define before including any of its files. The default in the absense of	2839	define before including any of its files. The default in the absence of
2744	autoconf is noted for every option.	2840	autoconf is noted for every option.
2745		2841
2746	=over 4	2842	=over 4
2747		2843
2748	=item EV_STANDALONE	2844	=item EV_STANDALONE
…		…
2754	F<event.h> that are not directly supported by the libev core alone.	2850	F<event.h> that are not directly supported by the libev core alone.
2755		2851
2756	=item EV_USE_MONOTONIC	2852	=item EV_USE_MONOTONIC
2757		2853
2758	If defined to be C<1>, libev will try to detect the availability of the	2854	If defined to be C<1>, libev will try to detect the availability of the
2759	monotonic clock option at both compiletime and runtime. Otherwise no use	2855	monotonic clock option at both compile time and runtime. Otherwise no use
2760	of the monotonic clock option will be attempted. If you enable this, you	2856	of the monotonic clock option will be attempted. If you enable this, you
2761	usually have to link against librt or something similar. Enabling it when	2857	usually have to link against librt or something similar. Enabling it when
2762	the functionality isn't available is safe, though, although you have	2858	the functionality isn't available is safe, though, although you have
2763	to make sure you link against any libraries where the C<clock_gettime>	2859	to make sure you link against any libraries where the C<clock_gettime>
2764	function is hiding in (often F<-lrt>).	2860	function is hiding in (often F<-lrt>).
2765		2861
2766	=item EV_USE_REALTIME	2862	=item EV_USE_REALTIME
2767		2863
2768	If defined to be C<1>, libev will try to detect the availability of the	2864	If defined to be C<1>, libev will try to detect the availability of the
2769	realtime clock option at compiletime (and assume its availability at	2865	real-time clock option at compile time (and assume its availability at
2770	runtime if successful). Otherwise no use of the realtime clock option will	2866	runtime if successful). Otherwise no use of the real-time clock option will
2771	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2867	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2772	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2868	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2773	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2869	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2774		2870
2775	=item EV_USE_NANOSLEEP	2871	=item EV_USE_NANOSLEEP
…		…
2786	2.7 or newer, otherwise disabled.	2882	2.7 or newer, otherwise disabled.
2787		2883
2788	=item EV_USE_SELECT	2884	=item EV_USE_SELECT
2789		2885
2790	If undefined or defined to be C<1>, libev will compile in support for the	2886	If undefined or defined to be C<1>, libev will compile in support for the
2791	C<select>(2) backend. No attempt at autodetection will be done: if no	2887	C<select>(2) backend. No attempt at auto-detection will be done: if no
2792	other method takes over, select will be it. Otherwise the select backend	2888	other method takes over, select will be it. Otherwise the select backend
2793	will not be compiled in.	2889	will not be compiled in.
2794		2890
2795	=item EV_SELECT_USE_FD_SET	2891	=item EV_SELECT_USE_FD_SET
2796		2892
2797	If defined to C<1>, then the select backend will use the system C<fd_set>	2893	If defined to C<1>, then the select backend will use the system C<fd_set>
2798	structure. This is useful if libev doesn't compile due to a missing	2894	structure. This is useful if libev doesn't compile due to a missing
2799	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	2895	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
2800	exotic systems. This usually limits the range of file descriptors to some	2896	exotic systems. This usually limits the range of file descriptors to some
2801	low limit such as 1024 or might have other limitations (winsocket only	2897	low limit such as 1024 or might have other limitations (winsocket only
2802	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	2898	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2803	influence the size of the C<fd_set> used.	2899	influence the size of the C<fd_set> used.
2804		2900
…		…
2853	otherwise another method will be used as fallback. This is the preferred	2949	otherwise another method will be used as fallback. This is the preferred
2854	backend for Solaris 10 systems.	2950	backend for Solaris 10 systems.
2855		2951
2856	=item EV_USE_DEVPOLL	2952	=item EV_USE_DEVPOLL
2857		2953
2858	reserved for future expansion, works like the USE symbols above.	2954	Reserved for future expansion, works like the USE symbols above.
2859		2955
2860	=item EV_USE_INOTIFY	2956	=item EV_USE_INOTIFY
2861		2957
2862	If defined to be C<1>, libev will compile in support for the Linux inotify	2958	If defined to be C<1>, libev will compile in support for the Linux inotify
2863	interface to speed up C<ev_stat> watchers. Its actual availability will	2959	interface to speed up C<ev_stat> watchers. Its actual availability will
…		…
2870	access is atomic with respect to other threads or signal contexts. No such	2966	access is atomic with respect to other threads or signal contexts. No such
2871	type is easily found in the C language, so you can provide your own type	2967	type is easily found in the C language, so you can provide your own type
2872	that you know is safe for your purposes. It is used both for signal handler "locking"	2968	that you know is safe for your purposes. It is used both for signal handler "locking"
2873	as well as for signal and thread safety in C<ev_async> watchers.	2969	as well as for signal and thread safety in C<ev_async> watchers.
2874		2970
2875	In the absense of this define, libev will use C<sig_atomic_t volatile>	2971	In the absence of this define, libev will use C<sig_atomic_t volatile>
2876	(from F<signal.h>), which is usually good enough on most platforms.	2972	(from F<signal.h>), which is usually good enough on most platforms.
2877		2973
2878	=item EV_H	2974	=item EV_H
2879		2975
2880	The name of the F<ev.h> header file used to include it. The default if	2976	The name of the F<ev.h> header file used to include it. The default if
…		…
2919	When doing priority-based operations, libev usually has to linearly search	3015	When doing priority-based operations, libev usually has to linearly search
2920	all the priorities, so having many of them (hundreds) uses a lot of space	3016	all the priorities, so having many of them (hundreds) uses a lot of space
2921	and time, so using the defaults of five priorities (-2 .. +2) is usually	3017	and time, so using the defaults of five priorities (-2 .. +2) is usually
2922	fine.	3018	fine.
2923		3019
2924	If your embedding app does not need any priorities, defining these both to	3020	If your embedding application does not need any priorities, defining these both to
2925	C<0> will save some memory and cpu.	3021	C<0> will save some memory and CPU.
2926		3022
2927	=item EV_PERIODIC_ENABLE	3023	=item EV_PERIODIC_ENABLE
2928		3024
2929	If undefined or defined to be C<1>, then periodic timers are supported. If	3025	If undefined or defined to be C<1>, then periodic timers are supported. If
2930	defined to be C<0>, then they are not. Disabling them saves a few kB of	3026	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
2957	defined to be C<0>, then they are not.	3053	defined to be C<0>, then they are not.
2958		3054
2959	=item EV_MINIMAL	3055	=item EV_MINIMAL
2960		3056
2961	If you need to shave off some kilobytes of code at the expense of some	3057	If you need to shave off some kilobytes of code at the expense of some
2962	speed, define this symbol to C<1>. Currently only used for gcc to override	3058	speed, define this symbol to C<1>. Currently this is used to override some
2963	some inlining decisions, saves roughly 30% codesize of amd64.	3059	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3060	much smaller 2-heap for timer management over the default 4-heap.
2964		3061
2965	=item EV_PID_HASHSIZE	3062	=item EV_PID_HASHSIZE
2966		3063
2967	C<ev_child> watchers use a small hash table to distribute workload by	3064	C<ev_child> watchers use a small hash table to distribute workload by
2968	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3065	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
…		…
2975	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	3072	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2976	usually more than enough. If you need to manage thousands of C<ev_stat>	3073	usually more than enough. If you need to manage thousands of C<ev_stat>
2977	watchers you might want to increase this value (I<must> be a power of	3074	watchers you might want to increase this value (I<must> be a power of
2978	two).	3075	two).
2979		3076
		3077	=item EV_USE_4HEAP
		3078
		3079	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3080	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3081	to C<1>. The 4-heap uses more complicated (longer) code but has
		3082	noticeably faster performance with many (thousands) of watchers.
		3083
		3084	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3085	(disabled).
		3086
		3087	=item EV_HEAP_CACHE_AT
		3088
		3089	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3090	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3091	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3092	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3093	but avoids random read accesses on heap changes. This improves performance
		3094	noticeably with with many (hundreds) of watchers.
		3095
		3096	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3097	(disabled).
		3098
		3099	=item EV_VERIFY
		3100
		3101	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3102	be done: If set to C<0>, no internal verification code will be compiled
		3103	in. If set to C<1>, then verification code will be compiled in, but not
		3104	called. If set to C<2>, then the internal verification code will be
		3105	called once per loop, which can slow down libev. If set to C<3>, then the
		3106	verification code will be called very frequently, which will slow down
		3107	libev considerably.
		3108
		3109	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3110	C<0.>
		3111
2980	=item EV_COMMON	3112	=item EV_COMMON
2981		3113
2982	By default, all watchers have a C<void *data> member. By redefining	3114	By default, all watchers have a C<void *data> member. By redefining
2983	this macro to a something else you can include more and other types of	3115	this macro to a something else you can include more and other types of
2984	members. You have to define it each time you include one of the files,	3116	members. You have to define it each time you include one of the files,
2985	though, and it must be identical each time.	3117	though, and it must be identical each time.
2986		3118
2987	For example, the perl EV module uses something like this:	3119	For example, the perl EV module uses something like this:
2988		3120
2989	#define EV_COMMON \	3121	#define EV_COMMON \
2990	SV *self; /* contains this struct */ \	3122	SV *self; /* contains this struct */ \
2991	SV *cb_sv, *fh /* note no trailing ";" */	3123	SV *cb_sv, *fh /* note no trailing ";" */
2992		3124
2993	=item EV_CB_DECLARE (type)	3125	=item EV_CB_DECLARE (type)
2994		3126
2995	=item EV_CB_INVOKE (watcher, revents)	3127	=item EV_CB_INVOKE (watcher, revents)
2996		3128
…		…
3003	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3135	avoid the C<struct ev_loop *> as first argument in all cases, or to use
3004	method calls instead of plain function calls in C++.	3136	method calls instead of plain function calls in C++.
3005		3137
3006	=head2 EXPORTED API SYMBOLS	3138	=head2 EXPORTED API SYMBOLS
3007		3139
3008	If you need to re-export the API (e.g. via a dll) and you need a list of	3140	If you need to re-export the API (e.g. via a DLL) and you need a list of
3009	exported symbols, you can use the provided F<Symbol.*> files which list	3141	exported symbols, you can use the provided F<Symbol.*> files which list
3010	all public symbols, one per line:	3142	all public symbols, one per line:
3011		3143
3012	Symbols.ev for libev proper	3144	Symbols.ev for libev proper
3013	Symbols.event for the libevent emulation	3145	Symbols.event for the libevent emulation
3014		3146
3015	This can also be used to rename all public symbols to avoid clashes with	3147	This can also be used to rename all public symbols to avoid clashes with
3016	multiple versions of libev linked together (which is obviously bad in	3148	multiple versions of libev linked together (which is obviously bad in
3017	itself, but sometimes it is inconvinient to avoid this).	3149	itself, but sometimes it is inconvenient to avoid this).
3018		3150
3019	A sed command like this will create wrapper C<#define>'s that you need to	3151	A sed command like this will create wrapper C<#define>'s that you need to
3020	include before including F<ev.h>:	3152	include before including F<ev.h>:
3021		3153
3022	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3154	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3039	file.	3171	file.
3040		3172
3041	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3173	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3042	that everybody includes and which overrides some configure choices:	3174	that everybody includes and which overrides some configure choices:
3043		3175
3044	#define EV_MINIMAL 1	3176	#define EV_MINIMAL 1
3045	#define EV_USE_POLL 0	3177	#define EV_USE_POLL 0
3046	#define EV_MULTIPLICITY 0	3178	#define EV_MULTIPLICITY 0
3047	#define EV_PERIODIC_ENABLE 0	3179	#define EV_PERIODIC_ENABLE 0
3048	#define EV_STAT_ENABLE 0	3180	#define EV_STAT_ENABLE 0
3049	#define EV_FORK_ENABLE 0	3181	#define EV_FORK_ENABLE 0
3050	#define EV_CONFIG_H <config.h>	3182	#define EV_CONFIG_H <config.h>
3051	#define EV_MINPRI 0	3183	#define EV_MINPRI 0
3052	#define EV_MAXPRI 0	3184	#define EV_MAXPRI 0
3053		3185
3054	#include "ev++.h"	3186	#include "ev++.h"
3055		3187
3056	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3188	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3057		3189
3058	#include "ev_cpp.h"	3190	#include "ev_cpp.h"
3059	#include "ev.c"	3191	#include "ev.c"
		3192
		3193
		3194	=head1 THREADS AND COROUTINES
		3195
		3196	=head2 THREADS
		3197
		3198	Libev itself is completely thread-safe, but it uses no locking. This
		3199	means that you can use as many loops as you want in parallel, as long as
		3200	only one thread ever calls into one libev function with the same loop
		3201	parameter.
		3202
		3203	Or put differently: calls with different loop parameters can be done in
		3204	parallel from multiple threads, calls with the same loop parameter must be
		3205	done serially (but can be done from different threads, as long as only one
		3206	thread ever is inside a call at any point in time, e.g. by using a mutex
		3207	per loop).
		3208
		3209	If you want to know which design (one loop, locking, or multiple loops
		3210	without or something else still) is best for your problem, then I cannot
		3211	help you. I can give some generic advice however:
		3212
		3213	=over 4
		3214
		3215	=item * most applications have a main thread: use the default libev loop
		3216	in that thread, or create a separate thread running only the default loop.
		3217
		3218	This helps integrating other libraries or software modules that use libev
		3219	themselves and don't care/know about threading.
		3220
		3221	=item * one loop per thread is usually a good model.
		3222
		3223	Doing this is almost never wrong, sometimes a better-performance model
		3224	exists, but it is always a good start.
		3225
		3226	=item * other models exist, such as the leader/follower pattern, where one
		3227	loop is handed through multiple threads in a kind of round-robin fashion.
		3228
		3229	Choosing a model is hard - look around, learn, know that usually you can do
		3230	better than you currently do :-)
		3231
		3232	=item * often you need to talk to some other thread which blocks in the
		3233	event loop - C<ev_async> watchers can be used to wake them up from other
		3234	threads safely (or from signal contexts...).
		3235
		3236	=back
		3237
		3238	=head2 COROUTINES
		3239
		3240	Libev is much more accommodating to coroutines ("cooperative threads"):
		3241	libev fully supports nesting calls to it's functions from different
		3242	coroutines (e.g. you can call C<ev_loop> on the same loop from two
		3243	different coroutines and switch freely between both coroutines running the
		3244	loop, as long as you don't confuse yourself). The only exception is that
		3245	you must not do this from C<ev_periodic> reschedule callbacks.
		3246
		3247	Care has been invested into making sure that libev does not keep local
		3248	state inside C<ev_loop>, and other calls do not usually allow coroutine
		3249	switches.
3060		3250
3061		3251
3062	=head1 COMPLEXITIES	3252	=head1 COMPLEXITIES
3063		3253
3064	In this section the complexities of (many of) the algorithms used inside	3254	In this section the complexities of (many of) the algorithms used inside
…		…
3096	correct watcher to remove. The lists are usually short (you don't usually	3286	correct watcher to remove. The lists are usually short (you don't usually
3097	have many watchers waiting for the same fd or signal).	3287	have many watchers waiting for the same fd or signal).
3098		3288
3099	=item Finding the next timer in each loop iteration: O(1)	3289	=item Finding the next timer in each loop iteration: O(1)
3100		3290
3101	By virtue of using a binary heap, the next timer is always found at the	3291	By virtue of using a binary or 4-heap, the next timer is always found at a
3102	beginning of the storage array.	3292	fixed position in the storage array.
3103		3293
3104	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3294	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3105		3295
3106	A change means an I/O watcher gets started or stopped, which requires	3296	A change means an I/O watcher gets started or stopped, which requires
3107	libev to recalculate its status (and possibly tell the kernel, depending	3297	libev to recalculate its status (and possibly tell the kernel, depending
3108	on backend and wether C<ev_io_set> was used).	3298	on backend and whether C<ev_io_set> was used).
3109		3299
3110	=item Activating one watcher (putting it into the pending state): O(1)	3300	=item Activating one watcher (putting it into the pending state): O(1)
3111		3301
3112	=item Priority handling: O(number_of_priorities)	3302	=item Priority handling: O(number_of_priorities)
3113		3303
…		…
3120		3310
3121	=item Processing ev_async_send: O(number_of_async_watchers)	3311	=item Processing ev_async_send: O(number_of_async_watchers)
3122		3312
3123	=item Processing signals: O(max_signal_number)	3313	=item Processing signals: O(max_signal_number)
3124		3314
3125	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3315	Sending involves a system call I<iff> there were no other C<ev_async_send>
3126	calls in the current loop iteration. Checking for async and signal events	3316	calls in the current loop iteration. Checking for async and signal events
3127	involves iterating over all running async watchers or all signal numbers.	3317	involves iterating over all running async watchers or all signal numbers.
3128		3318
3129	=back	3319	=back
3130		3320
3131		3321
3132	=head1 Win32 platform limitations and workarounds	3322	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3133		3323
3134	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3324	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3135	requires, and its I/O model is fundamentally incompatible with the POSIX	3325	requires, and its I/O model is fundamentally incompatible with the POSIX
3136	model. Libev still offers limited functionality on this platform in	3326	model. Libev still offers limited functionality on this platform in
3137	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3327	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3138	descriptors. This only applies when using Win32 natively, not when using	3328	descriptors. This only applies when using Win32 natively, not when using
3139	e.g. cygwin.	3329	e.g. cygwin.
3140		3330
		3331	Lifting these limitations would basically require the full
		3332	re-implementation of the I/O system. If you are into these kinds of
		3333	things, then note that glib does exactly that for you in a very portable
		3334	way (note also that glib is the slowest event library known to man).
		3335
3141	There is no supported compilation method available on windows except	3336	There is no supported compilation method available on windows except
3142	embedding it into other applications.	3337	embedding it into other applications.
3143		3338
		3339	Not a libev limitation but worth mentioning: windows apparently doesn't
		3340	accept large writes: instead of resulting in a partial write, windows will
		3341	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3342	so make sure you only write small amounts into your sockets (less than a
		3343	megabyte seems safe, but thsi apparently depends on the amount of memory
		3344	available).
		3345
3144	Due to the many, low, and arbitrary limits on the win32 platform and the	3346	Due to the many, low, and arbitrary limits on the win32 platform and
3145	abysmal performance of winsockets, using a large number of sockets is not	3347	the abysmal performance of winsockets, using a large number of sockets
3146	recommended (and not reasonable). If your program needs to use more than	3348	is not recommended (and not reasonable). If your program needs to use
3147	a hundred or so sockets, then likely it needs to use a totally different	3349	more than a hundred or so sockets, then likely it needs to use a totally
3148	implementation for windows, as libev offers the POSIX model, which cannot	3350	different implementation for windows, as libev offers the POSIX readiness
3149	be implemented efficiently on windows (microsoft monopoly games).	3351	notification model, which cannot be implemented efficiently on windows
		3352	(Microsoft monopoly games).
		3353
		3354	A typical way to use libev under windows is to embed it (see the embedding
		3355	section for details) and use the following F<evwrap.h> header file instead
		3356	of F<ev.h>:
		3357
		3358	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3359	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3360
		3361	#include "ev.h"
		3362
		3363	And compile the following F<evwrap.c> file into your project (make sure
		3364	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3365
		3366	#include "evwrap.h"
		3367	#include "ev.c"
3150		3368
3151	=over 4	3369	=over 4
3152		3370
3153	=item The winsocket select function	3371	=item The winsocket select function
3154		3372
3155	The winsocket C<select> function doesn't follow POSIX in that it requires	3373	The winsocket C<select> function doesn't follow POSIX in that it
3156	socket I<handles> and not socket I<file descriptors>. This makes select	3374	requires socket I<handles> and not socket I<file descriptors> (it is
3157	very inefficient, and also requires a mapping from file descriptors	3375	also extremely buggy). This makes select very inefficient, and also
3158	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,	3376	requires a mapping from file descriptors to socket handles (the Microsoft
3159	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor	3377	C runtime provides the function C<_open_osfhandle> for this). See the
3160	symbols for more info.	3378	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3379	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3161		3380
3162	The configuration for a "naked" win32 using the microsoft runtime	3381	The configuration for a "naked" win32 using the Microsoft runtime
3163	libraries and raw winsocket select is:	3382	libraries and raw winsocket select is:
3164		3383
3165	#define EV_USE_SELECT 1	3384	#define EV_USE_SELECT 1
3166	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3385	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3167		3386
3168	Note that winsockets handling of fd sets is O(n), so you can easily get a	3387	Note that winsockets handling of fd sets is O(n), so you can easily get a
3169	complexity in the O(n²) range when using win32.	3388	complexity in the O(n²) range when using win32.
3170		3389
3171	=item Limited number of file descriptors	3390	=item Limited number of file descriptors
3172		3391
3173	Windows has numerous arbitrary (and low) limits on things. Early versions	3392	Windows has numerous arbitrary (and low) limits on things.
3174	of winsocket's select only supported waiting for a max. of C<64> handles	3393
		3394	Early versions of winsocket's select only supported waiting for a maximum
3175	(probably owning to the fact that all windows kernels can only wait for	3395	of C<64> handles (probably owning to the fact that all windows kernels
3176	C<64> things at the same time internally; microsoft recommends spawning a	3396	can only wait for C<64> things at the same time internally; Microsoft
3177	chain of threads and wait for 63 handles and the previous thread in each).	3397	recommends spawning a chain of threads and wait for 63 handles and the
		3398	previous thread in each. Great).
3178		3399
3179	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3400	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3180	to some high number (e.g. C<2048>) before compiling the winsocket select	3401	to some high number (e.g. C<2048>) before compiling the winsocket select
3181	call (which might be in libev or elsewhere, for example, perl does its own	3402	call (which might be in libev or elsewhere, for example, perl does its own
3182	select emulation on windows).	3403	select emulation on windows).
3183		3404
3184	Another limit is the number of file descriptors in the microsoft runtime	3405	Another limit is the number of file descriptors in the Microsoft runtime
3185	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3406	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3186	or something like this inside microsoft). You can increase this by calling	3407	or something like this inside Microsoft). You can increase this by calling
3187	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3408	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3188	arbitrary limit), but is broken in many versions of the microsoft runtime	3409	arbitrary limit), but is broken in many versions of the Microsoft runtime
3189	libraries.	3410	libraries.
3190		3411
3191	This might get you to about C<512> or C<2048> sockets (depending on	3412	This might get you to about C<512> or C<2048> sockets (depending on
3192	windows version and/or the phase of the moon). To get more, you need to	3413	windows version and/or the phase of the moon). To get more, you need to
3193	wrap all I/O functions and provide your own fd management, but the cost of	3414	wrap all I/O functions and provide your own fd management, but the cost of
3194	calling select (O(n²)) will likely make this unworkable.	3415	calling select (O(n²)) will likely make this unworkable.
3195		3416
3196	=back	3417	=back
3197		3418
3198		3419
		3420	=head1 PORTABILITY REQUIREMENTS
		3421
		3422	In addition to a working ISO-C implementation, libev relies on a few
		3423	additional extensions:
		3424
		3425	=over 4
		3426
		3427	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3428	calling conventions regardless of C<ev_watcher_type *>.
		3429
		3430	Libev assumes not only that all watcher pointers have the same internal
		3431	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3432	assumes that the same (machine) code can be used to call any watcher
		3433	callback: The watcher callbacks have different type signatures, but libev
		3434	calls them using an C<ev_watcher *> internally.
		3435
		3436	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3437
		3438	The type C<sig_atomic_t volatile> (or whatever is defined as
		3439	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3440	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3441	believed to be sufficiently portable.
		3442
		3443	=item C<sigprocmask> must work in a threaded environment
		3444
		3445	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3446	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3447	pthread implementations will either allow C<sigprocmask> in the "main
		3448	thread" or will block signals process-wide, both behaviours would
		3449	be compatible with libev. Interaction between C<sigprocmask> and
		3450	C<pthread_sigmask> could complicate things, however.
		3451
		3452	The most portable way to handle signals is to block signals in all threads
		3453	except the initial one, and run the default loop in the initial thread as
		3454	well.
		3455
		3456	=item C<long> must be large enough for common memory allocation sizes
		3457
		3458	To improve portability and simplify using libev, libev uses C<long>
		3459	internally instead of C<size_t> when allocating its data structures. On
		3460	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3461	is still at least 31 bits everywhere, which is enough for hundreds of
		3462	millions of watchers.
		3463
		3464	=item C<double> must hold a time value in seconds with enough accuracy
		3465
		3466	The type C<double> is used to represent timestamps. It is required to
		3467	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3468	enough for at least into the year 4000. This requirement is fulfilled by
		3469	implementations implementing IEEE 754 (basically all existing ones).
		3470
		3471	=back
		3472
		3473	If you know of other additional requirements drop me a note.
		3474
		3475
		3476	=head1 COMPILER WARNINGS
		3477
		3478	Depending on your compiler and compiler settings, you might get no or a
		3479	lot of warnings when compiling libev code. Some people are apparently
		3480	scared by this.
		3481
		3482	However, these are unavoidable for many reasons. For one, each compiler
		3483	has different warnings, and each user has different tastes regarding
		3484	warning options. "Warn-free" code therefore cannot be a goal except when
		3485	targeting a specific compiler and compiler-version.
		3486
		3487	Another reason is that some compiler warnings require elaborate
		3488	workarounds, or other changes to the code that make it less clear and less
		3489	maintainable.
		3490
		3491	And of course, some compiler warnings are just plain stupid, or simply
		3492	wrong (because they don't actually warn about the condition their message
		3493	seems to warn about).
		3494
		3495	While libev is written to generate as few warnings as possible,
		3496	"warn-free" code is not a goal, and it is recommended not to build libev
		3497	with any compiler warnings enabled unless you are prepared to cope with
		3498	them (e.g. by ignoring them). Remember that warnings are just that:
		3499	warnings, not errors, or proof of bugs.
		3500
		3501
		3502	=head1 VALGRIND
		3503
		3504	Valgrind has a special section here because it is a popular tool that is
		3505	highly useful, but valgrind reports are very hard to interpret.
		3506
		3507	If you think you found a bug (memory leak, uninitialised data access etc.)
		3508	in libev, then check twice: If valgrind reports something like:
		3509
		3510	==2274== definitely lost: 0 bytes in 0 blocks.
		3511	==2274== possibly lost: 0 bytes in 0 blocks.
		3512	==2274== still reachable: 256 bytes in 1 blocks.
		3513
		3514	Then there is no memory leak. Similarly, under some circumstances,
		3515	valgrind might report kernel bugs as if it were a bug in libev, or it
		3516	might be confused (it is a very good tool, but only a tool).
		3517
		3518	If you are unsure about something, feel free to contact the mailing list
		3519	with the full valgrind report and an explanation on why you think this is
		3520	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3521	no bug" answer and take the chance of learning how to interpret valgrind
		3522	properly.
		3523
		3524	If you need, for some reason, empty reports from valgrind for your project
		3525	I suggest using suppression lists.
		3526
		3527
3199	=head1 AUTHOR	3528	=head1 AUTHOR
3200		3529
3201	Marc Lehmann <libev@schmorp.de>.	3530	Marc Lehmann <libev@schmorp.de>.
3202		3531

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