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Revision 1.139 by root, Wed Apr 2 05:51:40 2008 UTC vs.
Revision 1.167 by root, Mon Jun 9 14:11:30 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 rewiring a syscall per fd change, no fork support and bad	380	cases and requiring a system call per fd change, no fork support and bad
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.
…		…
647	respectively).	664	respectively).
648		665
649	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	666	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
650	running when nothing else is active.	667	running when nothing else is active.
651		668
652	struct ev_signal exitsig;	669	struct ev_signal exitsig;
653	ev_signal_init (&exitsig, sig_cb, SIGINT);	670	ev_signal_init (&exitsig, sig_cb, SIGINT);
654	ev_signal_start (loop, &exitsig);	671	ev_signal_start (loop, &exitsig);
655	evf_unref (loop);	672	evf_unref (loop);
656		673
657	Example: For some weird reason, unregister the above signal handler again.	674	Example: For some weird reason, unregister the above signal handler again.
658		675
659	ev_ref (loop);	676	ev_ref (loop);
660	ev_signal_stop (loop, &exitsig);	677	ev_signal_stop (loop, &exitsig);
661		678
662	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	679	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
663		680
664	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	681	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
665		682
…		…
687	to spend more time collecting timeouts, at the expense of increased	704	to spend more time collecting timeouts, at the expense of increased
688	latency (the watcher callback will be called later). C<ev_io> watchers	705	latency (the watcher callback will be called later). C<ev_io> watchers
689	will not be affected. Setting this to a non-null value will not introduce	706	will not be affected. Setting this to a non-null value will not introduce
690	any overhead in libev.	707	any overhead in libev.
691		708
692	Many (busy) programs can usually benefit by setting the io collect	709	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	710	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	711	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>,	712	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.	713	as this approaches the timing granularity of most systems.
		714
		715	=item ev_loop_verify (loop)
		716
		717	This function only does something when C<EV_VERIFY> support has been
		718	compiled in. It tries to go through all internal structures and checks
		719	them for validity. If anything is found to be inconsistent, it will print
		720	an error message to standard error and call C<abort ()>.
		721
		722	This can be used to catch bugs inside libev itself: under normal
		723	circumstances, this function will never abort as of course libev keeps its
		724	data structures consistent.
697		725
698	=back	726	=back
699		727
700		728
701	=head1 ANATOMY OF A WATCHER	729	=head1 ANATOMY OF A WATCHER
702		730
703	A watcher is a structure that you create and register to record your	731	A watcher is a structure that you create and register to record your
704	interest in some event. For instance, if you want to wait for STDIN to	732	interest in some event. For instance, if you want to wait for STDIN to
705	become readable, you would create an C<ev_io> watcher for that:	733	become readable, you would create an C<ev_io> watcher for that:
706		734
707	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	735	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
708	{	736	{
709	ev_io_stop (w);	737	ev_io_stop (w);
710	ev_unloop (loop, EVUNLOOP_ALL);	738	ev_unloop (loop, EVUNLOOP_ALL);
711	}	739	}
712		740
713	struct ev_loop *loop = ev_default_loop (0);	741	struct ev_loop *loop = ev_default_loop (0);
714	struct ev_io stdin_watcher;	742	struct ev_io stdin_watcher;
715	ev_init (&stdin_watcher, my_cb);	743	ev_init (&stdin_watcher, my_cb);
716	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	744	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
717	ev_io_start (loop, &stdin_watcher);	745	ev_io_start (loop, &stdin_watcher);
718	ev_loop (loop, 0);	746	ev_loop (loop, 0);
719		747
720	As you can see, you are responsible for allocating the memory for your	748	As you can see, you are responsible for allocating the memory for your
721	watcher structures (and it is usually a bad idea to do this on the stack,	749	watcher structures (and it is usually a bad idea to do this on the stack,
722	although this can sometimes be quite valid).	750	although this can sometimes be quite valid).
723		751
724	Each watcher structure must be initialised by a call to C<ev_init	752	Each watcher structure must be initialised by a call to C<ev_init
725	(watcher *, callback)>, which expects a callback to be provided. This	753	(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	754	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	755	watchers, each time the event loop detects that the file descriptor given
728	is readable and/or writable).	756	is readable and/or writable).
729		757
730	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	758	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro
731	with arguments specific to this watcher type. There is also a macro	759	with arguments specific to this watcher type. There is also a macro
…		…
807		835
808	The given async watcher has been asynchronously notified (see C<ev_async>).	836	The given async watcher has been asynchronously notified (see C<ev_async>).
809		837
810	=item C<EV_ERROR>	838	=item C<EV_ERROR>
811		839
812	An unspecified error has occured, the watcher has been stopped. This might	840	An unspecified error has occurred, the watcher has been stopped. This might
813	happen because the watcher could not be properly started because libev	841	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	842	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	843	problem. You best act on it by reporting the problem and somehow coping
816	with the watcher being stopped.	844	with the watcher being stopped.
817		845
818	Libev will usually signal a few "dummy" events together with an error,	846	Libev will usually signal a few "dummy" events together with an error,
819	for example it might indicate that a fd is readable or writable, and if	847	for example it might indicate that a fd is readable or writable, and if
820	your callbacks is well-written it can just attempt the operation and cope	848	your callbacks is well-written it can just attempt the operation and cope
821	with the error from read() or write(). This will not work in multithreaded	849	with the error from read() or write(). This will not work in multi-threaded
822	programs, though, so beware.	850	programs, though, so beware.
823		851
824	=back	852	=back
825		853
826	=head2 GENERIC WATCHER FUNCTIONS	854	=head2 GENERIC WATCHER FUNCTIONS
…		…
856	Although some watcher types do not have type-specific arguments	884	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.	885	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
858		886
859	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	887	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
860		888
861	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	889	This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
862	calls into a single call. This is the most convinient method to initialise	890	calls into a single call. This is the most convenient method to initialise
863	a watcher. The same limitations apply, of course.	891	a watcher. The same limitations apply, of course.
864		892
865	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	893	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
866		894
867	Starts (activates) the given watcher. Only active watchers will receive	895	Starts (activates) the given watcher. Only active watchers will receive
…		…
950	to associate arbitrary data with your watcher. If you need more data and	978	to associate arbitrary data with your watcher. If you need more data and
951	don't want to allocate memory and store a pointer to it in that data	979	don't want to allocate memory and store a pointer to it in that data
952	member, you can also "subclass" the watcher type and provide your own	980	member, you can also "subclass" the watcher type and provide your own
953	data:	981	data:
954		982
955	struct my_io	983	struct my_io
956	{	984	{
957	struct ev_io io;	985	struct ev_io io;
958	int otherfd;	986	int otherfd;
959	void *somedata;	987	void *somedata;
960	struct whatever *mostinteresting;	988	struct whatever *mostinteresting;
961	}	989	}
962		990
963	And since your callback will be called with a pointer to the watcher, you	991	And since your callback will be called with a pointer to the watcher, you
964	can cast it back to your own type:	992	can cast it back to your own type:
965		993
966	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	994	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
967	{	995	{
968	struct my_io *w = (struct my_io *)w_;	996	struct my_io *w = (struct my_io *)w_;
969	...	997	...
970	}	998	}
971		999
972	More interesting and less C-conformant ways of casting your callback type	1000	More interesting and less C-conformant ways of casting your callback type
973	instead have been omitted.	1001	instead have been omitted.
974		1002
975	Another common scenario is having some data structure with multiple	1003	Another common scenario is having some data structure with multiple
976	watchers:	1004	watchers:
977		1005
978	struct my_biggy	1006	struct my_biggy
979	{	1007	{
980	int some_data;	1008	int some_data;
981	ev_timer t1;	1009	ev_timer t1;
982	ev_timer t2;	1010	ev_timer t2;
983	}	1011	}
984		1012
985	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1013	In this case getting the pointer to C<my_biggy> is a bit more complicated,
986	you need to use C<offsetof>:	1014	you need to use C<offsetof>:
987		1015
988	#include <stddef.h>	1016	#include <stddef.h>
989		1017
990	static void	1018	static void
991	t1_cb (EV_P_ struct ev_timer *w, int revents)	1019	t1_cb (EV_P_ struct ev_timer *w, int revents)
992	{	1020	{
993	struct my_biggy big = (struct my_biggy *	1021	struct my_biggy big = (struct my_biggy *
994	(((char *)w) - offsetof (struct my_biggy, t1));	1022	(((char *)w) - offsetof (struct my_biggy, t1));
995	}	1023	}
996		1024
997	static void	1025	static void
998	t2_cb (EV_P_ struct ev_timer *w, int revents)	1026	t2_cb (EV_P_ struct ev_timer *w, int revents)
999	{	1027	{
1000	struct my_biggy big = (struct my_biggy *	1028	struct my_biggy big = (struct my_biggy *
1001	(((char *)w) - offsetof (struct my_biggy, t2));	1029	(((char *)w) - offsetof (struct my_biggy, t2));
1002	}	1030	}
1003		1031
1004		1032
1005	=head1 WATCHER TYPES	1033	=head1 WATCHER TYPES
1006		1034
1007	This section describes each watcher in detail, but will not repeat	1035	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	1064	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	1065	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
1038	C<EVBACKEND_POLL>).	1066	C<EVBACKEND_POLL>).
1039		1067
1040	Another thing you have to watch out for is that it is quite easy to	1068	Another thing you have to watch out for is that it is quite easy to
1041	receive "spurious" readyness notifications, that is your callback might	1069	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	1070	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	1071	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	1072	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	1073	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	1074	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.	1075	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1048		1076
1049	If you cannot run the fd in non-blocking mode (for example you should not	1077	If you cannot run the fd in non-blocking mode (for example you should not
1050	play around with an Xlib connection), then you have to seperately re-test	1078	play around with an Xlib connection), then you have to separately re-test
1051	whether a file descriptor is really ready with a known-to-be good interface	1079	whether a file descriptor is really ready with a known-to-be good interface
1052	such as poll (fortunately in our Xlib example, Xlib already does this on	1080	such as poll (fortunately in our Xlib example, Xlib already does this on
1053	its own, so its quite safe to use).	1081	its own, so its quite safe to use).
1054		1082
1055	=head3 The special problem of disappearing file descriptors	1083	=head3 The special problem of disappearing file descriptors
…		…
1115	=item ev_io_init (ev_io *, callback, int fd, int events)	1143	=item ev_io_init (ev_io *, callback, int fd, int events)
1116		1144
1117	=item ev_io_set (ev_io *, int fd, int events)	1145	=item ev_io_set (ev_io *, int fd, int events)
1118		1146
1119	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1147	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1120	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1148	receive events for and events is either C<EV_READ>, C<EV_WRITE> or
1121	C<EV_READ | EV_WRITE> to receive the given events.	1149	C<EV_READ | EV_WRITE> to receive the given events.
1122		1150
1123	=item int fd [read-only]	1151	=item int fd [read-only]
1124		1152
1125	The file descriptor being watched.	1153	The file descriptor being watched.
…		…
1134		1162
1135	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1163	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1136	readable, but only once. Since it is likely line-buffered, you could	1164	readable, but only once. Since it is likely line-buffered, you could
1137	attempt to read a whole line in the callback.	1165	attempt to read a whole line in the callback.
1138		1166
1139	static void	1167	static void
1140	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1168	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1141	{	1169	{
1142	ev_io_stop (loop, w);	1170	ev_io_stop (loop, w);
1143	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1171	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1144	}	1172	}
1145		1173
1146	...	1174	...
1147	struct ev_loop *loop = ev_default_init (0);	1175	struct ev_loop *loop = ev_default_init (0);
1148	struct ev_io stdin_readable;	1176	struct ev_io stdin_readable;
1149	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1177	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1150	ev_io_start (loop, &stdin_readable);	1178	ev_io_start (loop, &stdin_readable);
1151	ev_loop (loop, 0);	1179	ev_loop (loop, 0);
1152		1180
1153		1181
1154	=head2 C<ev_timer> - relative and optionally repeating timeouts	1182	=head2 C<ev_timer> - relative and optionally repeating timeouts
1155		1183
1156	Timer watchers are simple relative timers that generate an event after a	1184	Timer watchers are simple relative timers that generate an event after a
1157	given time, and optionally repeating in regular intervals after that.	1185	given time, and optionally repeating in regular intervals after that.
1158		1186
1159	The timers are based on real time, that is, if you register an event that	1187	The timers are based on real time, that is, if you register an event that
1160	times out after an hour and you reset your system clock to last years	1188	times out after an hour and you reset your system clock to January last
1161	time, it will still time out after (roughly) and hour. "Roughly" because	1189	year, it will still time out after (roughly) and hour. "Roughly" because
1162	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1190	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1163	monotonic clock option helps a lot here).	1191	monotonic clock option helps a lot here).
1164		1192
1165	The relative timeouts are calculated relative to the C<ev_now ()>	1193	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	1194	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	1196	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:	1197	on the current time, use something like this to adjust for this:
1170		1198
1171	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1199	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1172		1200
1173	The callback is guarenteed to be invoked only when its timeout has passed,	1201	The callback is guaranteed to be invoked only after its timeout has passed,
1174	but if multiple timers become ready during the same loop iteration then	1202	but if multiple timers become ready during the same loop iteration then
1175	order of execution is undefined.	1203	order of execution is undefined.
1176		1204
1177	=head3 Watcher-Specific Functions and Data Members	1205	=head3 Watcher-Specific Functions and Data Members
1178		1206
…		…
1180		1208
1181	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1209	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1182		1210
1183	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1211	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1184		1212
1185	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1213	Configure the timer to trigger after C<after> seconds. If C<repeat>
1186	C<0.>, then it will automatically be stopped. If it is positive, then the	1214	is C<0.>, then it will automatically be stopped once the timeout is
1187	timer will automatically be configured to trigger again C<repeat> seconds	1215	reached. If it is positive, then the timer will automatically be
1188	later, again, and again, until stopped manually.	1216	configured to trigger again C<repeat> seconds later, again, and again,
		1217	until stopped manually.
1189		1218
1190	The timer itself will do a best-effort at avoiding drift, that is, if you	1219	The timer itself will do a best-effort at avoiding drift, that is, if
1191	configure a timer to trigger every 10 seconds, then it will trigger at	1220	you configure a timer to trigger every 10 seconds, then it will normally
1192	exactly 10 second intervals. If, however, your program cannot keep up with	1221	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	1222	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.	1223	do stuff) the timer will not fire more than once per event loop iteration.
1195		1224
1196	=item ev_timer_again (loop, ev_timer *)	1225	=item ev_timer_again (loop, ev_timer *)
1197		1226
1198	This will act as if the timer timed out and restart it again if it is	1227	This will act as if the timer timed out and restart it again if it is
1199	repeating. The exact semantics are:	1228	repeating. The exact semantics are:
1200		1229
1201	If the timer is pending, its pending status is cleared.	1230	If the timer is pending, its pending status is cleared.
1202		1231
1203	If the timer is started but nonrepeating, stop it (as if it timed out).	1232	If the timer is started but non-repeating, stop it (as if it timed out).
1204		1233
1205	If the timer is repeating, either start it if necessary (with the	1234	If the timer is repeating, either start it if necessary (with the
1206	C<repeat> value), or reset the running timer to the C<repeat> value.	1235	C<repeat> value), or reset the running timer to the C<repeat> value.
1207		1236
1208	This sounds a bit complicated, but here is a useful and typical	1237	This sounds a bit complicated, but here is a useful and typical
1209	example: Imagine you have a tcp connection and you want a so-called idle	1238	example: Imagine you have a TCP connection and you want a so-called idle
1210	timeout, that is, you want to be called when there have been, say, 60	1239	timeout, that is, you want to be called when there have been, say, 60
1211	seconds of inactivity on the socket. The easiest way to do this is to	1240	seconds of inactivity on the socket. The easiest way to do this is to
1212	configure an C<ev_timer> with a C<repeat> value of C<60> and then call	1241	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1213	C<ev_timer_again> each time you successfully read or write some data. If	1242	C<ev_timer_again> each time you successfully read or write some data. If
1214	you go into an idle state where you do not expect data to travel on the	1243	you go into an idle state where you do not expect data to travel on the
…		…
1240		1269
1241	=head3 Examples	1270	=head3 Examples
1242		1271
1243	Example: Create a timer that fires after 60 seconds.	1272	Example: Create a timer that fires after 60 seconds.
1244		1273
1245	static void	1274	static void
1246	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1275	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1247	{	1276	{
1248	.. one minute over, w is actually stopped right here	1277	.. one minute over, w is actually stopped right here
1249	}	1278	}
1250		1279
1251	struct ev_timer mytimer;	1280	struct ev_timer mytimer;
1252	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1281	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1253	ev_timer_start (loop, &mytimer);	1282	ev_timer_start (loop, &mytimer);
1254		1283
1255	Example: Create a timeout timer that times out after 10 seconds of	1284	Example: Create a timeout timer that times out after 10 seconds of
1256	inactivity.	1285	inactivity.
1257		1286
1258	static void	1287	static void
1259	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1288	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1260	{	1289	{
1261	.. ten seconds without any activity	1290	.. ten seconds without any activity
1262	}	1291	}
1263		1292
1264	struct ev_timer mytimer;	1293	struct ev_timer mytimer;
1265	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1294	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1266	ev_timer_again (&mytimer); /* start timer */	1295	ev_timer_again (&mytimer); /* start timer */
1267	ev_loop (loop, 0);	1296	ev_loop (loop, 0);
1268		1297
1269	// and in some piece of code that gets executed on any "activity":	1298	// and in some piece of code that gets executed on any "activity":
1270	// reset the timeout to start ticking again at 10 seconds	1299	// reset the timeout to start ticking again at 10 seconds
1271	ev_timer_again (&mytimer);	1300	ev_timer_again (&mytimer);
1272		1301
1273		1302
1274	=head2 C<ev_periodic> - to cron or not to cron?	1303	=head2 C<ev_periodic> - to cron or not to cron?
1275		1304
1276	Periodic watchers are also timers of a kind, but they are very versatile	1305	Periodic watchers are also timers of a kind, but they are very versatile
1277	(and unfortunately a bit complex).	1306	(and unfortunately a bit complex).
1278		1307
1279	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1308	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
1280	but on wallclock time (absolute time). You can tell a periodic watcher	1309	but on wall clock time (absolute time). You can tell a periodic watcher
1281	to trigger "at" some specific point in time. For example, if you tell a	1310	to trigger after some specific point in time. For example, if you tell a
1282	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1311	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()
1283	+ 10.>) and then reset your system clock to the last year, then it will	1312	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1313	clock to January of the previous year, then it will take more than year
1284	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1314	to trigger the event (unlike an C<ev_timer>, which would still trigger
1285	roughly 10 seconds later).	1315	roughly 10 seconds later as it uses a relative timeout).
1286		1316
1287	They can also be used to implement vastly more complex timers, such as	1317	C<ev_periodic>s can also be used to implement vastly more complex timers,
1288	triggering an event on each midnight, local time or other, complicated,	1318	such as triggering an event on each "midnight, local time", or other
1289	rules.	1319	complicated, rules.
1290		1320
1291	As with timers, the callback is guarenteed to be invoked only when the	1321	As with timers, the callback is guaranteed to be invoked only when the
1292	time (C<at>) has been passed, but if multiple periodic timers become ready	1322	time (C<at>) has passed, but if multiple periodic timers become ready
1293	during the same loop iteration then order of execution is undefined.	1323	during the same loop iteration then order of execution is undefined.
1294		1324
1295	=head3 Watcher-Specific Functions and Data Members	1325	=head3 Watcher-Specific Functions and Data Members
1296		1326
1297	=over 4	1327	=over 4
…		…
1305		1335
1306	=over 4	1336	=over 4
1307		1337
1308	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1338	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1309		1339
1310	In this configuration the watcher triggers an event at the wallclock time	1340	In this configuration the watcher triggers an event after the wall clock
1311	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1341	time C<at> has passed and doesn't repeat. It will not adjust when a time
1312	that is, if it is to be run at January 1st 2011 then it will run when the	1342	jump occurs, that is, if it is to be run at January 1st 2011 then it will
1313	system time reaches or surpasses this time.	1343	run when the system time reaches or surpasses this time.
1314		1344
1315	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1345	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1316		1346
1317	In this mode the watcher will always be scheduled to time out at the next	1347	In this mode the watcher will always be scheduled to time out at the next
1318	C<at + N * interval> time (for some integer N, which can also be negative)	1348	C<at + N * interval> time (for some integer N, which can also be negative)
1319	and then repeat, regardless of any time jumps.	1349	and then repeat, regardless of any time jumps.
1320		1350
1321	This can be used to create timers that do not drift with respect to system	1351	This can be used to create timers that do not drift with respect to system
1322	time:	1352	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1353	the hour:
1323		1354
1324	ev_periodic_set (&periodic, 0., 3600., 0);	1355	ev_periodic_set (&periodic, 0., 3600., 0);
1325		1356
1326	This doesn't mean there will always be 3600 seconds in between triggers,	1357	This doesn't mean there will always be 3600 seconds in between triggers,
1327	but only that the the callback will be called when the system time shows a	1358	but only that the callback will be called when the system time shows a
1328	full hour (UTC), or more correctly, when the system time is evenly divisible	1359	full hour (UTC), or more correctly, when the system time is evenly divisible
1329	by 3600.	1360	by 3600.
1330		1361
1331	Another way to think about it (for the mathematically inclined) is that	1362	Another way to think about it (for the mathematically inclined) is that
1332	C<ev_periodic> will try to run the callback in this mode at the next possible	1363	C<ev_periodic> will try to run the callback in this mode at the next possible
1333	time where C<time = at (mod interval)>, regardless of any time jumps.	1364	time where C<time = at (mod interval)>, regardless of any time jumps.
1334		1365
1335	For numerical stability it is preferable that the C<at> value is near	1366	For numerical stability it is preferable that the C<at> value is near
1336	C<ev_now ()> (the current time), but there is no range requirement for	1367	C<ev_now ()> (the current time), but there is no range requirement for
1337	this value.	1368	this value, and in fact is often specified as zero.
		1369
		1370	Note also that there is an upper limit to how often a timer can fire (CPU
		1371	speed for example), so if C<interval> is very small then timing stability
		1372	will of course deteriorate. Libev itself tries to be exact to be about one
		1373	millisecond (if the OS supports it and the machine is fast enough).
1338		1374
1339	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1375	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1340		1376
1341	In this mode the values for C<interval> and C<at> are both being	1377	In this mode the values for C<interval> and C<at> are both being
1342	ignored. Instead, each time the periodic watcher gets scheduled, the	1378	ignored. Instead, each time the periodic watcher gets scheduled, the
1343	reschedule callback will be called with the watcher as first, and the	1379	reschedule callback will be called with the watcher as first, and the
1344	current time as second argument.	1380	current time as second argument.
1345		1381
1346	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1382	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1347	ever, or make any event loop modifications>. If you need to stop it,	1383	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		1384
		1385	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1386	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1387	only event loop modification you are allowed to do).
		1388
1351	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1389	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1352	ev_tstamp now)>, e.g.:	1390	*w, ev_tstamp now)>, e.g.:
1353		1391
1354	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1392	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1355	{	1393	{
1356	return now + 60.;	1394	return now + 60.;
1357	}	1395	}
…		…
1359	It must return the next time to trigger, based on the passed time value	1397	It must return the next time to trigger, based on the passed time value
1360	(that is, the lowest time value larger than to the second argument). It	1398	(that is, the lowest time value larger than to the second argument). It
1361	will usually be called just before the callback will be triggered, but	1399	will usually be called just before the callback will be triggered, but
1362	might be called at other times, too.	1400	might be called at other times, too.
1363		1401
1364	NOTE: I<< This callback must always return a time that is later than the	1402	NOTE: I<< This callback must always return a time that is higher than or
1365	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.	1403	equal to the passed C<now> value >>.
1366		1404
1367	This can be used to create very complex timers, such as a timer that	1405	This can be used to create very complex timers, such as a timer that
1368	triggers on each midnight, local time. To do this, you would calculate the	1406	triggers on "next midnight, local time". To do this, you would calculate the
1369	next midnight after C<now> and return the timestamp value for this. How	1407	next midnight after C<now> and return the timestamp value for this. How
1370	you do this is, again, up to you (but it is not trivial, which is the main	1408	you do this is, again, up to you (but it is not trivial, which is the main
1371	reason I omitted it as an example).	1409	reason I omitted it as an example).
1372		1410
1373	=back	1411	=back
…		…
1377	Simply stops and restarts the periodic watcher again. This is only useful	1415	Simply stops and restarts the periodic watcher again. This is only useful
1378	when you changed some parameters or the reschedule callback would return	1416	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	1417	a different time than the last time it was called (e.g. in a crond like
1380	program when the crontabs have changed).	1418	program when the crontabs have changed).
1381		1419
		1420	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1421
		1422	When active, returns the absolute time that the watcher is supposed to
		1423	trigger next.
		1424
1382	=item ev_tstamp offset [read-write]	1425	=item ev_tstamp offset [read-write]
1383		1426
1384	When repeating, this contains the offset value, otherwise this is the	1427	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>).	1428	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1386		1429
…		…
1397		1440
1398	The current reschedule callback, or C<0>, if this functionality is	1441	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	1442	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.	1443	the periodic timer fires or C<ev_periodic_again> is being called.
1401		1444
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	1445	=back
1408		1446
1409	=head3 Examples	1447	=head3 Examples
1410		1448
1411	Example: Call a callback every hour, or, more precisely, whenever the	1449	Example: Call a callback every hour, or, more precisely, whenever the
1412	system clock is divisible by 3600. The callback invocation times have	1450	system clock is divisible by 3600. The callback invocation times have
1413	potentially a lot of jittering, but good long-term stability.	1451	potentially a lot of jitter, but good long-term stability.
1414		1452
1415	static void	1453	static void
1416	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1454	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1417	{	1455	{
1418	... its now a full hour (UTC, or TAI or whatever your clock follows)	1456	... its now a full hour (UTC, or TAI or whatever your clock follows)
1419	}	1457	}
1420		1458
1421	struct ev_periodic hourly_tick;	1459	struct ev_periodic hourly_tick;
1422	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1460	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1423	ev_periodic_start (loop, &hourly_tick);	1461	ev_periodic_start (loop, &hourly_tick);
1424		1462
1425	Example: The same as above, but use a reschedule callback to do it:	1463	Example: The same as above, but use a reschedule callback to do it:
1426		1464
1427	#include <math.h>	1465	#include <math.h>
1428		1466
1429	static ev_tstamp	1467	static ev_tstamp
1430	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1468	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1431	{	1469	{
1432	return fmod (now, 3600.) + 3600.;	1470	return fmod (now, 3600.) + 3600.;
1433	}	1471	}
1434		1472
1435	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1473	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1436		1474
1437	Example: Call a callback every hour, starting now:	1475	Example: Call a callback every hour, starting now:
1438		1476
1439	struct ev_periodic hourly_tick;	1477	struct ev_periodic hourly_tick;
1440	ev_periodic_init (&hourly_tick, clock_cb,	1478	ev_periodic_init (&hourly_tick, clock_cb,
1441	fmod (ev_now (loop), 3600.), 3600., 0);	1479	fmod (ev_now (loop), 3600.), 3600., 0);
1442	ev_periodic_start (loop, &hourly_tick);	1480	ev_periodic_start (loop, &hourly_tick);
1443		1481
1444		1482
1445	=head2 C<ev_signal> - signal me when a signal gets signalled!	1483	=head2 C<ev_signal> - signal me when a signal gets signalled!
1446		1484
1447	Signal watchers will trigger an event when the process receives a specific	1485	Signal watchers will trigger an event when the process receives a specific
…		…
1455	as you don't register any with libev). Similarly, when the last signal	1493	as you don't register any with libev). Similarly, when the last signal
1456	watcher for a signal is stopped libev will reset the signal handler to	1494	watcher for a signal is stopped libev will reset the signal handler to
1457	SIG_DFL (regardless of what it was set to before).	1495	SIG_DFL (regardless of what it was set to before).
1458		1496
1459	If possible and supported, libev will install its handlers with	1497	If possible and supported, libev will install its handlers with
1460	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1498	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1461	interrupted. If you have a problem with syscalls getting interrupted by	1499	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	1500	signals you can block all signals in an C<ev_check> watcher and unblock
1463	them in an C<ev_prepare> watcher.	1501	them in an C<ev_prepare> watcher.
1464		1502
1465	=head3 Watcher-Specific Functions and Data Members	1503	=head3 Watcher-Specific Functions and Data Members
1466		1504
…		…
1481		1519
1482	=head3 Examples	1520	=head3 Examples
1483		1521
1484	Example: Try to exit cleanly on SIGINT and SIGTERM.	1522	Example: Try to exit cleanly on SIGINT and SIGTERM.
1485		1523
1486	static void	1524	static void
1487	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1525	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1488	{	1526	{
1489	ev_unloop (loop, EVUNLOOP_ALL);	1527	ev_unloop (loop, EVUNLOOP_ALL);
1490	}	1528	}
1491		1529
1492	struct ev_signal signal_watcher;	1530	struct ev_signal signal_watcher;
1493	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1531	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1494	ev_signal_start (loop, &sigint_cb);	1532	ev_signal_start (loop, &sigint_cb);
1495		1533
1496		1534
1497	=head2 C<ev_child> - watch out for process status changes	1535	=head2 C<ev_child> - watch out for process status changes
1498		1536
1499	Child watchers trigger when your process receives a SIGCHLD in response to	1537	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1501	is permissible to install a child watcher I<after> the child has been	1539	is permissible to install a child watcher I<after> the child has been
1502	forked (which implies it might have already exited), as long as the event	1540	forked (which implies it might have already exited), as long as the event
1503	loop isn't entered (or is continued from a watcher).	1541	loop isn't entered (or is continued from a watcher).
1504		1542
1505	Only the default event loop is capable of handling signals, and therefore	1543	Only the default event loop is capable of handling signals, and therefore
1506	you can only rgeister child watchers in the default event loop.	1544	you can only register child watchers in the default event loop.
1507		1545
1508	=head3 Process Interaction	1546	=head3 Process Interaction
1509		1547
1510	Libev grabs C<SIGCHLD> as soon as the default event loop is	1548	Libev grabs C<SIGCHLD> as soon as the default event loop is
1511	initialised. This is necessary to guarantee proper behaviour even if	1549	initialised. This is necessary to guarantee proper behaviour even if
1512	the first child watcher is started after the child exits. The occurance	1550	the first child watcher is started after the child exits. The occurrence
1513	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1551	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1514	synchronously as part of the event loop processing. Libev always reaps all	1552	synchronously as part of the event loop processing. Libev always reaps all
1515	children, even ones not watched.	1553	children, even ones not watched.
1516		1554
1517	=head3 Overriding the Built-In Processing	1555	=head3 Overriding the Built-In Processing
…		…
1559	=head3 Examples	1597	=head3 Examples
1560		1598
1561	Example: C<fork()> a new process and install a child handler to wait for	1599	Example: C<fork()> a new process and install a child handler to wait for
1562	its completion.	1600	its completion.
1563		1601
1564	ev_child cw;	1602	ev_child cw;
1565		1603
1566	static void	1604	static void
1567	child_cb (EV_P_ struct ev_child *w, int revents)	1605	child_cb (EV_P_ struct ev_child *w, int revents)
1568	{	1606	{
1569	ev_child_stop (EV_A_ w);	1607	ev_child_stop (EV_A_ w);
1570	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1608	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1571	}	1609	}
1572		1610
1573	pid_t pid = fork ();	1611	pid_t pid = fork ();
1574		1612
1575	if (pid < 0)	1613	if (pid < 0)
1576	// error	1614	// error
1577	else if (pid == 0)	1615	else if (pid == 0)
1578	{	1616	{
1579	// the forked child executes here	1617	// the forked child executes here
1580	exit (1);	1618	exit (1);
1581	}	1619	}
1582	else	1620	else
1583	{	1621	{
1584	ev_child_init (&cw, child_cb, pid, 0);	1622	ev_child_init (&cw, child_cb, pid, 0);
1585	ev_child_start (EV_DEFAULT_ &cw);	1623	ev_child_start (EV_DEFAULT_ &cw);
1586	}	1624	}
1587		1625
1588		1626
1589	=head2 C<ev_stat> - did the file attributes just change?	1627	=head2 C<ev_stat> - did the file attributes just change?
1590		1628
1591	This watches a filesystem path for attribute changes. That is, it calls	1629	This watches a file system path for attribute changes. That is, it calls
1592	C<stat> regularly (or when the OS says it changed) and sees if it changed	1630	C<stat> regularly (or when the OS says it changed) and sees if it changed
1593	compared to the last time, invoking the callback if it did.	1631	compared to the last time, invoking the callback if it did.
1594		1632
1595	The path does not need to exist: changing from "path exists" to "path does	1633	The path does not need to exist: changing from "path exists" to "path does
1596	not exist" is a status change like any other. The condition "path does	1634	not exist" is a status change like any other. The condition "path does
…		…
1614	as even with OS-supported change notifications, this can be	1652	as even with OS-supported change notifications, this can be
1615	resource-intensive.	1653	resource-intensive.
1616		1654
1617	At the time of this writing, only the Linux inotify interface is	1655	At the time of this writing, only the Linux inotify interface is
1618	implemented (implementing kqueue support is left as an exercise for the	1656	implemented (implementing kqueue support is left as an exercise for the
		1657	reader, note, however, that the author sees no way of implementing ev_stat
1619	reader). Inotify will be used to give hints only and should not change the	1658	semantics with kqueue). Inotify will be used to give hints only and should
1620	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1659	not change the semantics of C<ev_stat> watchers, which means that libev
1621	to fall back to regular polling again even with inotify, but changes are	1660	sometimes needs to fall back to regular polling again even with inotify,
1622	usually detected immediately, and if the file exists there will be no	1661	but changes are usually detected immediately, and if the file exists there
1623	polling.	1662	will be no polling.
1624		1663
1625	=head3 ABI Issues (Largefile Support)	1664	=head3 ABI Issues (Largefile Support)
1626		1665
1627	Libev by default (unless the user overrides this) uses the default	1666	Libev by default (unless the user overrides this) uses the default
1628	compilation environment, which means that on systems with optionally	1667	compilation environment, which means that on systems with optionally
1629	disabled large file support, you get the 32 bit version of the stat	1668	disabled large file support, you get the 32 bit version of the stat
1630	structure. When using the library from programs that change the ABI to	1669	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	1670	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	1671	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	1672	obviously the case with any flags that change the ABI, but the problem is
1634	most noticably with ev_stat and largefile support.	1673	most noticeably with ev_stat and large file support.
1635		1674
1636	=head3 Inotify	1675	=head3 Inotify
1637		1676
1638	When C<inotify (7)> support has been compiled into libev (generally only	1677	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	1678	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	1679	change detection where possible. The inotify descriptor will be created lazily
1641	when the first C<ev_stat> watcher is being started.	1680	when the first C<ev_stat> watcher is being started.
1642		1681
1643	Inotify presense does not change the semantics of C<ev_stat> watchers	1682	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	1683	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	1684	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.	1685	there are many cases where libev has to resort to regular C<stat> polling.
1647		1686
1648	(There is no support for kqueue, as apparently it cannot be used to	1687	(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	1688	implement this functionality, due to the requirement of having a file
1650	descriptor open on the object at all times).	1689	descriptor open on the object at all times).
1651		1690
1652	=head3 The special problem of stat time resolution	1691	=head3 The special problem of stat time resolution
1653		1692
1654	The C<stat ()> syscall only supports full-second resolution portably, and	1693	The C<stat ()> system call only supports full-second resolution portably, and
1655	even on systems where the resolution is higher, many filesystems still	1694	even on systems where the resolution is higher, many file systems still
1656	only support whole seconds.	1695	only support whole seconds.
1657		1696
1658	That means that, if the time is the only thing that changes, you might	1697	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	1698	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	1699	calls your callback, which does something. When there is another update
1661	the same second, C<ev_stat> will be unable to detect it.	1700	within the same second, C<ev_stat> will be unable to detect it as the stat
		1701	data does not change.
1662		1702
1663	The solution to this is to delay acting on a change for a second (or till	1703	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>	1704	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>	1705	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	1706	ev_timer_again (loop, w)>).
1667	systems.	1707
		1708	The C<.02> offset is added to work around small timing inconsistencies
		1709	of some operating systems (where the second counter of the current time
		1710	might be be delayed. One such system is the Linux kernel, where a call to
		1711	C<gettimeofday> might return a timestamp with a full second later than
		1712	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1713	update file times then there will be a small window where the kernel uses
		1714	the previous second to update file times but libev might already execute
		1715	the timer callback).
1668		1716
1669	=head3 Watcher-Specific Functions and Data Members	1717	=head3 Watcher-Specific Functions and Data Members
1670		1718
1671	=over 4	1719	=over 4
1672		1720
…		…
1678	C<path>. The C<interval> is a hint on how quickly a change is expected to	1726	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	1727	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	1728	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.	1729	path for as long as the watcher is active.
1682		1730
1683	The callback will be receive C<EV_STAT> when a change was detected,	1731	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	1732	to the attributes at the time the watcher was started (or the last change
1685	last change was detected).	1733	was detected).
1686		1734
1687	=item ev_stat_stat (loop, ev_stat *)	1735	=item ev_stat_stat (loop, ev_stat *)
1688		1736
1689	Updates the stat buffer immediately with new values. If you change the	1737	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	1738	watched path in your callback, you could call this function to avoid
1691	detecting this change (while introducing a race condition). Can also be	1739	detecting this change (while introducing a race condition if you are not
1692	useful simply to find out the new values.	1740	the only one changing the path). Can also be useful simply to find out the
		1741	new values.
1693		1742
1694	=item ev_statdata attr [read-only]	1743	=item ev_statdata attr [read-only]
1695		1744
1696	The most-recently detected attributes of the file. Although the type is of	1745	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	1746	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	1747	suitable for your system, but you can only rely on the POSIX-standardised
		1748	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.	1749	some error while C<stat>ing the file.
1700		1750
1701	=item ev_statdata prev [read-only]	1751	=item ev_statdata prev [read-only]
1702		1752
1703	The previous attributes of the file. The callback gets invoked whenever	1753	The previous attributes of the file. The callback gets invoked whenever
1704	C<prev> != C<attr>.	1754	C<prev> != C<attr>, or, more precisely, one or more of these members
		1755	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1756	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1705		1757
1706	=item ev_tstamp interval [read-only]	1758	=item ev_tstamp interval [read-only]
1707		1759
1708	The specified interval.	1760	The specified interval.
1709		1761
1710	=item const char *path [read-only]	1762	=item const char *path [read-only]
1711		1763
1712	The filesystem path that is being watched.	1764	The file system path that is being watched.
1713		1765
1714	=back	1766	=back
1715		1767
1716	=head3 Examples	1768	=head3 Examples
1717		1769
1718	Example: Watch C</etc/passwd> for attribute changes.	1770	Example: Watch C</etc/passwd> for attribute changes.
1719		1771
1720	static void	1772	static void
1721	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1773	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1722	{	1774	{
1723	/* /etc/passwd changed in some way */	1775	/* /etc/passwd changed in some way */
1724	if (w->attr.st_nlink)	1776	if (w->attr.st_nlink)
1725	{	1777	{
1726	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1778	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1727	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1779	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1728	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1780	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1729	}	1781	}
1730	else	1782	else
1731	/* you shalt not abuse printf for puts */	1783	/* you shalt not abuse printf for puts */
1732	puts ("wow, /etc/passwd is not there, expect problems. "	1784	puts ("wow, /etc/passwd is not there, expect problems. "
1733	"if this is windows, they already arrived\n");	1785	"if this is windows, they already arrived\n");
1734	}	1786	}
1735		1787
1736	...	1788	...
1737	ev_stat passwd;	1789	ev_stat passwd;
1738		1790
1739	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1791	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1740	ev_stat_start (loop, &passwd);	1792	ev_stat_start (loop, &passwd);
1741		1793
1742	Example: Like above, but additionally use a one-second delay so we do not	1794	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	1795	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	1796	one might do the work both on C<ev_stat> callback invocation I<and> on
1745	C<ev_timer> callback invocation).	1797	C<ev_timer> callback invocation).
1746		1798
1747	static ev_stat passwd;	1799	static ev_stat passwd;
1748	static ev_timer timer;	1800	static ev_timer timer;
1749		1801
1750	static void	1802	static void
1751	timer_cb (EV_P_ ev_timer *w, int revents)	1803	timer_cb (EV_P_ ev_timer *w, int revents)
1752	{	1804	{
1753	ev_timer_stop (EV_A_ w);	1805	ev_timer_stop (EV_A_ w);
1754		1806
1755	/* now it's one second after the most recent passwd change */	1807	/* now it's one second after the most recent passwd change */
1756	}	1808	}
1757		1809
1758	static void	1810	static void
1759	stat_cb (EV_P_ ev_stat *w, int revents)	1811	stat_cb (EV_P_ ev_stat *w, int revents)
1760	{	1812	{
1761	/* reset the one-second timer */	1813	/* reset the one-second timer */
1762	ev_timer_again (EV_A_ &timer);	1814	ev_timer_again (EV_A_ &timer);
1763	}	1815	}
1764		1816
1765	...	1817	...
1766	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1818	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1767	ev_stat_start (loop, &passwd);	1819	ev_stat_start (loop, &passwd);
1768	ev_timer_init (&timer, timer_cb, 0., 1.01);	1820	ev_timer_init (&timer, timer_cb, 0., 1.02);
1769		1821
1770		1822
1771	=head2 C<ev_idle> - when you've got nothing better to do...	1823	=head2 C<ev_idle> - when you've got nothing better to do...
1772		1824
1773	Idle watchers trigger events when no other events of the same or higher	1825	Idle watchers trigger events when no other events of the same or higher
…		…
1804	=head3 Examples	1856	=head3 Examples
1805		1857
1806	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1858	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1807	callback, free it. Also, use no error checking, as usual.	1859	callback, free it. Also, use no error checking, as usual.
1808		1860
1809	static void	1861	static void
1810	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1862	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1811	{	1863	{
1812	free (w);	1864	free (w);
1813	// now do something you wanted to do when the program has	1865	// now do something you wanted to do when the program has
1814	// no longer anything immediate to do.	1866	// no longer anything immediate to do.
1815	}	1867	}
1816		1868
1817	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1869	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1818	ev_idle_init (idle_watcher, idle_cb);	1870	ev_idle_init (idle_watcher, idle_cb);
1819	ev_idle_start (loop, idle_cb);	1871	ev_idle_start (loop, idle_cb);
1820		1872
1821		1873
1822	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1874	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1823		1875
1824	Prepare and check watchers are usually (but not always) used in tandem:	1876	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1843		1895
1844	This is done by examining in each prepare call which file descriptors need	1896	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	1897	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	1898	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	1899	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	1900	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	1901	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,	1902	callbacks will never actually be called (but must be valid nevertheless,
1851	because you never know, you know?).	1903	because you never know, you know?).
1852		1904
1853	As another example, the Perl Coro module uses these hooks to integrate	1905	As another example, the Perl Coro module uses these hooks to integrate
…		…
1861		1913
1862	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1914	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	1915	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,	1916	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	1917	too) should not activate ("feed") events into libev. While libev fully
1866	supports this, they will be called before other C<ev_check> watchers	1918	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	1919	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	1920	(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	1921	state until their C<ev_check> watcher ran (always remind yourself to
1870	coexist peacefully with others).	1922	coexist peacefully with others).
1871		1923
…		…
1886	=head3 Examples	1938	=head3 Examples
1887		1939
1888	There are a number of principal ways to embed other event loops or modules	1940	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	1941	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	1942	(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>	1943	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	1944	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1893	into the Glib event loop).	1945	Glib event loop).
1894		1946
1895	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	1947	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	1948	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	1949	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	1950	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.	1951	the callbacks for the IO/timeout watchers might not have been called yet.
1900		1952
1901	static ev_io iow [nfd];	1953	static ev_io iow [nfd];
1902	static ev_timer tw;	1954	static ev_timer tw;
1903		1955
1904	static void	1956	static void
1905	io_cb (ev_loop *loop, ev_io *w, int revents)	1957	io_cb (ev_loop *loop, ev_io *w, int revents)
1906	{	1958	{
1907	}	1959	}
1908		1960
1909	// create io watchers for each fd and a timer before blocking	1961	// create io watchers for each fd and a timer before blocking
1910	static void	1962	static void
1911	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1963	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1912	{	1964	{
1913	int timeout = 3600000;	1965	int timeout = 3600000;
1914	struct pollfd fds [nfd];	1966	struct pollfd fds [nfd];
1915	// actual code will need to loop here and realloc etc.	1967	// actual code will need to loop here and realloc etc.
1916	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1968	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1917		1969
1918	/* the callback is illegal, but won't be called as we stop during check */	1970	/* the callback is illegal, but won't be called as we stop during check */
1919	ev_timer_init (&tw, 0, timeout * 1e-3);	1971	ev_timer_init (&tw, 0, timeout * 1e-3);
1920	ev_timer_start (loop, &tw);	1972	ev_timer_start (loop, &tw);
1921		1973
1922	// create one ev_io per pollfd	1974	// create one ev_io per pollfd
1923	for (int i = 0; i < nfd; ++i)	1975	for (int i = 0; i < nfd; ++i)
1924	{	1976	{
1925	ev_io_init (iow + i, io_cb, fds [i].fd,	1977	ev_io_init (iow + i, io_cb, fds [i].fd,
1926	((fds [i].events & POLLIN ? EV_READ : 0)	1978	((fds [i].events & POLLIN ? EV_READ : 0)
1927	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1979	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1928		1980
1929	fds [i].revents = 0;	1981	fds [i].revents = 0;
1930	ev_io_start (loop, iow + i);	1982	ev_io_start (loop, iow + i);
1931	}	1983	}
1932	}	1984	}
1933		1985
1934	// stop all watchers after blocking	1986	// stop all watchers after blocking
1935	static void	1987	static void
1936	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1988	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1937	{	1989	{
1938	ev_timer_stop (loop, &tw);	1990	ev_timer_stop (loop, &tw);
1939		1991
1940	for (int i = 0; i < nfd; ++i)	1992	for (int i = 0; i < nfd; ++i)
1941	{	1993	{
1942	// set the relevant poll flags	1994	// set the relevant poll flags
1943	// could also call adns_processreadable etc. here	1995	// could also call adns_processreadable etc. here
1944	struct pollfd *fd = fds + i;	1996	struct pollfd *fd = fds + i;
1945	int revents = ev_clear_pending (iow + i);	1997	int revents = ev_clear_pending (iow + i);
1946	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	1998	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1947	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	1999	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1948		2000
1949	// now stop the watcher	2001	// now stop the watcher
1950	ev_io_stop (loop, iow + i);	2002	ev_io_stop (loop, iow + i);
1951	}	2003	}
1952		2004
1953	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2005	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1954	}	2006	}
1955		2007
1956	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2008	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.	2009	in the prepare watcher and would dispose of the check watcher.
1958		2010
1959	Method 3: If the module to be embedded supports explicit event	2011	Method 3: If the module to be embedded supports explicit event
1960	notification (adns does), you can also make use of the actual watcher	2012	notification (libadns does), you can also make use of the actual watcher
1961	callbacks, and only destroy/create the watchers in the prepare watcher.	2013	callbacks, and only destroy/create the watchers in the prepare watcher.
1962		2014
1963	static void	2015	static void
1964	timer_cb (EV_P_ ev_timer *w, int revents)	2016	timer_cb (EV_P_ ev_timer *w, int revents)
1965	{	2017	{
1966	adns_state ads = (adns_state)w->data;	2018	adns_state ads = (adns_state)w->data;
1967	update_now (EV_A);	2019	update_now (EV_A);
1968		2020
1969	adns_processtimeouts (ads, &tv_now);	2021	adns_processtimeouts (ads, &tv_now);
1970	}	2022	}
1971		2023
1972	static void	2024	static void
1973	io_cb (EV_P_ ev_io *w, int revents)	2025	io_cb (EV_P_ ev_io *w, int revents)
1974	{	2026	{
1975	adns_state ads = (adns_state)w->data;	2027	adns_state ads = (adns_state)w->data;
1976	update_now (EV_A);	2028	update_now (EV_A);
1977		2029
1978	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2030	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1979	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2031	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1980	}	2032	}
1981		2033
1982	// do not ever call adns_afterpoll	2034	// do not ever call adns_afterpoll
1983		2035
1984	Method 4: Do not use a prepare or check watcher because the module you	2036	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	2037	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	2038	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	2039	loop is now no longer controllable by EV. The C<Glib::EV> module does
1988	this.	2040	this.
1989		2041
1990	static gint	2042	static gint
1991	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2043	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1992	{	2044	{
1993	int got_events = 0;	2045	int got_events = 0;
1994		2046
1995	for (n = 0; n < nfds; ++n)	2047	for (n = 0; n < nfds; ++n)
1996	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2048	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1997		2049
1998	if (timeout >= 0)	2050	if (timeout >= 0)
1999	// create/start timer	2051	// create/start timer
2000		2052
2001	// poll	2053	// poll
2002	ev_loop (EV_A_ 0);	2054	ev_loop (EV_A_ 0);
2003		2055
2004	// stop timer again	2056	// stop timer again
2005	if (timeout >= 0)	2057	if (timeout >= 0)
2006	ev_timer_stop (EV_A_ &to);	2058	ev_timer_stop (EV_A_ &to);
2007		2059
2008	// stop io watchers again - their callbacks should have set	2060	// stop io watchers again - their callbacks should have set
2009	for (n = 0; n < nfds; ++n)	2061	for (n = 0; n < nfds; ++n)
2010	ev_io_stop (EV_A_ iow [n]);	2062	ev_io_stop (EV_A_ iow [n]);
2011		2063
2012	return got_events;	2064	return got_events;
2013	}	2065	}
2014		2066
2015		2067
2016	=head2 C<ev_embed> - when one backend isn't enough...	2068	=head2 C<ev_embed> - when one backend isn't enough...
2017		2069
2018	This is a rather advanced watcher type that lets you embed one event loop	2070	This is a rather advanced watcher type that lets you embed one event loop
…		…
2074		2126
2075	Configures the watcher to embed the given loop, which must be	2127	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	2128	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	2129	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,	2130	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).	2131	if you do not want that, you need to temporarily stop the embed watcher).
2080		2132
2081	=item ev_embed_sweep (loop, ev_embed *)	2133	=item ev_embed_sweep (loop, ev_embed *)
2082		2134
2083	Make a single, non-blocking sweep over the embedded loop. This works	2135	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	2136	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2085	apropriate way for embedded loops.	2137	appropriate way for embedded loops.
2086		2138
2087	=item struct ev_loop *other [read-only]	2139	=item struct ev_loop *other [read-only]
2088		2140
2089	The embedded event loop.	2141	The embedded event loop.
2090		2142
…		…
2092		2144
2093	=head3 Examples	2145	=head3 Examples
2094		2146
2095	Example: Try to get an embeddable event loop and embed it into the default	2147	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	2148	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	2149	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	2150	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2099	used).	2151	used).
2100		2152
2101	struct ev_loop *loop_hi = ev_default_init (0);	2153	struct ev_loop *loop_hi = ev_default_init (0);
2102	struct ev_loop *loop_lo = 0;	2154	struct ev_loop *loop_lo = 0;
2103	struct ev_embed embed;	2155	struct ev_embed embed;
2104		2156
2105	// see if there is a chance of getting one that works	2157	// see if there is a chance of getting one that works
2106	// (remember that a flags value of 0 means autodetection)	2158	// (remember that a flags value of 0 means autodetection)
2107	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2159	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2108	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2160	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2109	: 0;	2161	: 0;
2110		2162
2111	// if we got one, then embed it, otherwise default to loop_hi	2163	// if we got one, then embed it, otherwise default to loop_hi
2112	if (loop_lo)	2164	if (loop_lo)
2113	{	2165	{
2114	ev_embed_init (&embed, 0, loop_lo);	2166	ev_embed_init (&embed, 0, loop_lo);
2115	ev_embed_start (loop_hi, &embed);	2167	ev_embed_start (loop_hi, &embed);
2116	}	2168	}
2117	else	2169	else
2118	loop_lo = loop_hi;	2170	loop_lo = loop_hi;
2119		2171
2120	Example: Check if kqueue is available but not recommended and create	2172	Example: Check if kqueue is available but not recommended and create
2121	a kqueue backend for use with sockets (which usually work with any	2173	a kqueue backend for use with sockets (which usually work with any
2122	kqueue implementation). Store the kqueue/socket-only event loop in	2174	kqueue implementation). Store the kqueue/socket-only event loop in
2123	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2175	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2124		2176
2125	struct ev_loop *loop = ev_default_init (0);	2177	struct ev_loop *loop = ev_default_init (0);
2126	struct ev_loop *loop_socket = 0;	2178	struct ev_loop *loop_socket = 0;
2127	struct ev_embed embed;	2179	struct ev_embed embed;
2128		2180
2129	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2181	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2130	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2182	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2131	{	2183	{
2132	ev_embed_init (&embed, 0, loop_socket);	2184	ev_embed_init (&embed, 0, loop_socket);
2133	ev_embed_start (loop, &embed);	2185	ev_embed_start (loop, &embed);
2134	}	2186	}
2135		2187
2136	if (!loop_socket)	2188	if (!loop_socket)
2137	loop_socket = loop;	2189	loop_socket = loop;
2138		2190
2139	// now use loop_socket for all sockets, and loop for everything else	2191	// now use loop_socket for all sockets, and loop for everything else
2140		2192
2141		2193
2142	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2194	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2143		2195
2144	Fork watchers are called when a C<fork ()> was detected (usually because	2196	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2197		2249
2198	=item queueing from a signal handler context	2250	=item queueing from a signal handler context
2199		2251
2200	To implement race-free queueing, you simply add to the queue in the signal	2252	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	2253	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2202	some fictitiuous SIGUSR1 handler:	2254	some fictitious SIGUSR1 handler:
2203		2255
2204	static ev_async mysig;	2256	static ev_async mysig;
2205		2257
2206	static void	2258	static void
2207	sigusr1_handler (void)	2259	sigusr1_handler (void)
…		…
2281	=item ev_async_send (loop, ev_async *)	2333	=item ev_async_send (loop, ev_async *)
2282		2334
2283	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2335	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	2336	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	2337	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	2338	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2287	section below on what exactly this means).	2339	section below on what exactly this means).
2288		2340
2289	This call incurs the overhead of a syscall only once per loop iteration,	2341	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	2342	so while the overhead might be noticeable, it doesn't apply to repeated
2291	calls to C<ev_async_send>.	2343	calls to C<ev_async_send>.
		2344
		2345	=item bool = ev_async_pending (ev_async *)
		2346
		2347	Returns a non-zero value when C<ev_async_send> has been called on the
		2348	watcher but the event has not yet been processed (or even noted) by the
		2349	event loop.
		2350
		2351	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
		2352	the loop iterates next and checks for the watcher to have become active,
		2353	it will reset the flag again. C<ev_async_pending> can be used to very
		2354	quickly check whether invoking the loop might be a good idea.
		2355
		2356	Not that this does I<not> check whether the watcher itself is pending, only
		2357	whether it has been requested to make this watcher pending.
2292		2358
2293	=back	2359	=back
2294		2360
2295		2361
2296	=head1 OTHER FUNCTIONS	2362	=head1 OTHER FUNCTIONS
…		…
2307	or timeout without having to allocate/configure/start/stop/free one or	2373	or timeout without having to allocate/configure/start/stop/free one or
2308	more watchers yourself.	2374	more watchers yourself.
2309		2375
2310	If C<fd> is less than 0, then no I/O watcher will be started and events	2376	If C<fd> is less than 0, then no I/O watcher will be started and events
2311	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2377	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2312	C<events> set will be craeted and started.	2378	C<events> set will be created and started.
2313		2379
2314	If C<timeout> is less than 0, then no timeout watcher will be	2380	If C<timeout> is less than 0, then no timeout watcher will be
2315	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2381	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2316	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2382	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2317	dubious value.	2383	dubious value.
…		…
2319	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2385	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2320	passed an C<revents> set like normal event callbacks (a combination of	2386	passed an C<revents> set like normal event callbacks (a combination of
2321	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2387	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2322	value passed to C<ev_once>:	2388	value passed to C<ev_once>:
2323		2389
2324	static void stdin_ready (int revents, void *arg)	2390	static void stdin_ready (int revents, void *arg)
2325	{	2391	{
2326	if (revents & EV_TIMEOUT)	2392	if (revents & EV_TIMEOUT)
2327	/* doh, nothing entered */;	2393	/* doh, nothing entered */;
2328	else if (revents & EV_READ)	2394	else if (revents & EV_READ)
2329	/* stdin might have data for us, joy! */;	2395	/* stdin might have data for us, joy! */;
2330	}	2396	}
2331		2397
2332	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2398	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2333		2399
2334	=item ev_feed_event (ev_loop *, watcher *, int revents)	2400	=item ev_feed_event (ev_loop *, watcher *, int revents)
2335		2401
2336	Feeds the given event set into the event loop, as if the specified event	2402	Feeds the given event set into the event loop, as if the specified event
2337	had happened for the specified watcher (which must be a pointer to an	2403	had happened for the specified watcher (which must be a pointer to an
…		…
2342	Feed an event on the given fd, as if a file descriptor backend detected	2408	Feed an event on the given fd, as if a file descriptor backend detected
2343	the given events it.	2409	the given events it.
2344		2410
2345	=item ev_feed_signal_event (ev_loop *loop, int signum)	2411	=item ev_feed_signal_event (ev_loop *loop, int signum)
2346		2412
2347	Feed an event as if the given signal occured (C<loop> must be the default	2413	Feed an event as if the given signal occurred (C<loop> must be the default
2348	loop!).	2414	loop!).
2349		2415
2350	=back	2416	=back
2351		2417
2352		2418
…		…
2368		2434
2369	=item * Priorities are not currently supported. Initialising priorities	2435	=item * Priorities are not currently supported. Initialising priorities
2370	will fail and all watchers will have the same priority, even though there	2436	will fail and all watchers will have the same priority, even though there
2371	is an ev_pri field.	2437	is an ev_pri field.
2372		2438
		2439	=item * In libevent, the last base created gets the signals, in libev, the
		2440	first base created (== the default loop) gets the signals.
		2441
2373	=item * Other members are not supported.	2442	=item * Other members are not supported.
2374		2443
2375	=item * The libev emulation is I<not> ABI compatible to libevent, you need	2444	=item * The libev emulation is I<not> ABI compatible to libevent, you need
2376	to use the libev header file and library.	2445	to use the libev header file and library.
2377		2446
2378	=back	2447	=back
2379		2448
2380	=head1 C++ SUPPORT	2449	=head1 C++ SUPPORT
2381		2450
2382	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2451	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2383	you to use some convinience methods to start/stop watchers and also change	2452	you to use some convenience methods to start/stop watchers and also change
2384	the callback model to a model using method callbacks on objects.	2453	the callback model to a model using method callbacks on objects.
2385		2454
2386	To use it,	2455	To use it,
2387		2456
2388	#include <ev++.h>	2457	#include <ev++.h>
2389		2458
2390	This automatically includes F<ev.h> and puts all of its definitions (many	2459	This automatically includes F<ev.h> and puts all of its definitions (many
2391	of them macros) into the global namespace. All C++ specific things are	2460	of them macros) into the global namespace. All C++ specific things are
2392	put into the C<ev> namespace. It should support all the same embedding	2461	put into the C<ev> namespace. It should support all the same embedding
2393	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2462	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2460	your compiler is good :), then the method will be fully inlined into the	2529	your compiler is good :), then the method will be fully inlined into the
2461	thunking function, making it as fast as a direct C callback.	2530	thunking function, making it as fast as a direct C callback.
2462		2531
2463	Example: simple class declaration and watcher initialisation	2532	Example: simple class declaration and watcher initialisation
2464		2533
2465	struct myclass	2534	struct myclass
2466	{	2535	{
2467	void io_cb (ev::io &w, int revents) { }	2536	void io_cb (ev::io &w, int revents) { }
2468	}	2537	}
2469		2538
2470	myclass obj;	2539	myclass obj;
2471	ev::io iow;	2540	ev::io iow;
2472	iow.set <myclass, &myclass::io_cb> (&obj);	2541	iow.set <myclass, &myclass::io_cb> (&obj);
2473		2542
2474	=item w->set<function> (void *data = 0)	2543	=item w->set<function> (void *data = 0)
2475		2544
2476	Also sets a callback, but uses a static method or plain function as	2545	Also sets a callback, but uses a static method or plain function as
2477	callback. The optional C<data> argument will be stored in the watcher's	2546	callback. The optional C<data> argument will be stored in the watcher's
…		…
2481		2550
2482	See the method-C<set> above for more details.	2551	See the method-C<set> above for more details.
2483		2552
2484	Example:	2553	Example:
2485		2554
2486	static void io_cb (ev::io &w, int revents) { }	2555	static void io_cb (ev::io &w, int revents) { }
2487	iow.set <io_cb> ();	2556	iow.set <io_cb> ();
2488		2557
2489	=item w->set (struct ev_loop *)	2558	=item w->set (struct ev_loop *)
2490		2559
2491	Associates a different C<struct ev_loop> with this watcher. You can only	2560	Associates a different C<struct ev_loop> with this watcher. You can only
2492	do this when the watcher is inactive (and not pending either).	2561	do this when the watcher is inactive (and not pending either).
2493		2562
2494	=item w->set ([args])	2563	=item w->set ([arguments])
2495		2564
2496	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2565	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2497	called at least once. Unlike the C counterpart, an active watcher gets	2566	called at least once. Unlike the C counterpart, an active watcher gets
2498	automatically stopped and restarted when reconfiguring it with this	2567	automatically stopped and restarted when reconfiguring it with this
2499	method.	2568	method.
2500		2569
2501	=item w->start ()	2570	=item w->start ()
…		…
2525	=back	2594	=back
2526		2595
2527	Example: Define a class with an IO and idle watcher, start one of them in	2596	Example: Define a class with an IO and idle watcher, start one of them in
2528	the constructor.	2597	the constructor.
2529		2598
2530	class myclass	2599	class myclass
2531	{	2600	{
2532	ev::io io; void io_cb (ev::io &w, int revents);	2601	ev::io io; void io_cb (ev::io &w, int revents);
2533	ev:idle idle void idle_cb (ev::idle &w, int revents);	2602	ev:idle idle void idle_cb (ev::idle &w, int revents);
2534		2603
2535	myclass (int fd)	2604	myclass (int fd)
2536	{	2605	{
2537	io .set <myclass, &myclass::io_cb > (this);	2606	io .set <myclass, &myclass::io_cb > (this);
2538	idle.set <myclass, &myclass::idle_cb> (this);	2607	idle.set <myclass, &myclass::idle_cb> (this);
2539		2608
2540	io.start (fd, ev::READ);	2609	io.start (fd, ev::READ);
2541	}	2610	}
2542	};	2611	};
2543		2612
2544		2613
2545	=head1 OTHER LANGUAGE BINDINGS	2614	=head1 OTHER LANGUAGE BINDINGS
2546		2615
2547	Libev does not offer other language bindings itself, but bindings for a	2616	Libev does not offer other language bindings itself, but bindings for a
2548	numbe rof languages exist in the form of third-party packages. If you know	2617	number of languages exist in the form of third-party packages. If you know
2549	any interesting language binding in addition to the ones listed here, drop	2618	any interesting language binding in addition to the ones listed here, drop
2550	me a note.	2619	me a note.
2551		2620
2552	=over 4	2621	=over 4
2553		2622
…		…
2557	libev. EV is developed together with libev. Apart from the EV core module,	2626	libev. EV is developed together with libev. Apart from the EV core module,
2558	there are additional modules that implement libev-compatible interfaces	2627	there are additional modules that implement libev-compatible interfaces
2559	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the	2628	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
2560	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).	2629	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2561		2630
2562	It can be found and installed via CPAN, its homepage is found at	2631	It can be found and installed via CPAN, its homepage is at
2563	L<http://software.schmorp.de/pkg/EV>.	2632	L<http://software.schmorp.de/pkg/EV>.
2564		2633
		2634	=item Python
		2635
		2636	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2637	seems to be quite complete and well-documented. Note, however, that the
		2638	patch they require for libev is outright dangerous as it breaks the ABI
		2639	for everybody else, and therefore, should never be applied in an installed
		2640	libev (if python requires an incompatible ABI then it needs to embed
		2641	libev).
		2642
2565	=item Ruby	2643	=item Ruby
2566		2644
2567	Tony Arcieri has written a ruby extension that offers access to a subset	2645	Tony Arcieri has written a ruby extension that offers access to a subset
2568	of the libev API and adds filehandle abstractions, asynchronous DNS and	2646	of the libev API and adds file handle abstractions, asynchronous DNS and
2569	more on top of it. It can be found via gem servers. Its homepage is at	2647	more on top of it. It can be found via gem servers. Its homepage is at
2570	L<http://rev.rubyforge.org/>.	2648	L<http://rev.rubyforge.org/>.
2571		2649
2572	=item D	2650	=item D
2573		2651
…		…
2577	=back	2655	=back
2578		2656
2579		2657
2580	=head1 MACRO MAGIC	2658	=head1 MACRO MAGIC
2581		2659
2582	Libev can be compiled with a variety of options, the most fundamantal	2660	Libev can be compiled with a variety of options, the most fundamental
2583	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2661	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2584	functions and callbacks have an initial C<struct ev_loop *> argument.	2662	functions and callbacks have an initial C<struct ev_loop *> argument.
2585		2663
2586	To make it easier to write programs that cope with either variant, the	2664	To make it easier to write programs that cope with either variant, the
2587	following macros are defined:	2665	following macros are defined:
…		…
2592		2670
2593	This provides the loop I<argument> for functions, if one is required ("ev	2671	This provides the loop I<argument> for functions, if one is required ("ev
2594	loop argument"). The C<EV_A> form is used when this is the sole argument,	2672	loop argument"). The C<EV_A> form is used when this is the sole argument,
2595	C<EV_A_> is used when other arguments are following. Example:	2673	C<EV_A_> is used when other arguments are following. Example:
2596		2674
2597	ev_unref (EV_A);	2675	ev_unref (EV_A);
2598	ev_timer_add (EV_A_ watcher);	2676	ev_timer_add (EV_A_ watcher);
2599	ev_loop (EV_A_ 0);	2677	ev_loop (EV_A_ 0);
2600		2678
2601	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2679	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2602	which is often provided by the following macro.	2680	which is often provided by the following macro.
2603		2681
2604	=item C<EV_P>, C<EV_P_>	2682	=item C<EV_P>, C<EV_P_>
2605		2683
2606	This provides the loop I<parameter> for functions, if one is required ("ev	2684	This provides the loop I<parameter> for functions, if one is required ("ev
2607	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2685	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2608	C<EV_P_> is used when other parameters are following. Example:	2686	C<EV_P_> is used when other parameters are following. Example:
2609		2687
2610	// this is how ev_unref is being declared	2688	// this is how ev_unref is being declared
2611	static void ev_unref (EV_P);	2689	static void ev_unref (EV_P);
2612		2690
2613	// this is how you can declare your typical callback	2691	// this is how you can declare your typical callback
2614	static void cb (EV_P_ ev_timer *w, int revents)	2692	static void cb (EV_P_ ev_timer *w, int revents)
2615		2693
2616	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2694	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2617	suitable for use with C<EV_A>.	2695	suitable for use with C<EV_A>.
2618		2696
2619	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2697	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
2620		2698
2621	Similar to the other two macros, this gives you the value of the default	2699	Similar to the other two macros, this gives you the value of the default
2622	loop, if multiple loops are supported ("ev loop default").	2700	loop, if multiple loops are supported ("ev loop default").
		2701
		2702	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
		2703
		2704	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
		2705	default loop has been initialised (C<UC> == unchecked). Their behaviour
		2706	is undefined when the default loop has not been initialised by a previous
		2707	execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
		2708
		2709	It is often prudent to use C<EV_DEFAULT> when initialising the first
		2710	watcher in a function but use C<EV_DEFAULT_UC> afterwards.
2623		2711
2624	=back	2712	=back
2625		2713
2626	Example: Declare and initialise a check watcher, utilising the above	2714	Example: Declare and initialise a check watcher, utilising the above
2627	macros so it will work regardless of whether multiple loops are supported	2715	macros so it will work regardless of whether multiple loops are supported
2628	or not.	2716	or not.
2629		2717
2630	static void	2718	static void
2631	check_cb (EV_P_ ev_timer *w, int revents)	2719	check_cb (EV_P_ ev_timer *w, int revents)
2632	{	2720	{
2633	ev_check_stop (EV_A_ w);	2721	ev_check_stop (EV_A_ w);
2634	}	2722	}
2635		2723
2636	ev_check check;	2724	ev_check check;
2637	ev_check_init (&check, check_cb);	2725	ev_check_init (&check, check_cb);
2638	ev_check_start (EV_DEFAULT_ &check);	2726	ev_check_start (EV_DEFAULT_ &check);
2639	ev_loop (EV_DEFAULT_ 0);	2727	ev_loop (EV_DEFAULT_ 0);
2640		2728
2641	=head1 EMBEDDING	2729	=head1 EMBEDDING
2642		2730
2643	Libev can (and often is) directly embedded into host	2731	Libev can (and often is) directly embedded into host
2644	applications. Examples of applications that embed it include the Deliantra	2732	applications. Examples of applications that embed it include the Deliantra
…		…
2651	libev somewhere in your source tree).	2739	libev somewhere in your source tree).
2652		2740
2653	=head2 FILESETS	2741	=head2 FILESETS
2654		2742
2655	Depending on what features you need you need to include one or more sets of files	2743	Depending on what features you need you need to include one or more sets of files
2656	in your app.	2744	in your application.
2657		2745
2658	=head3 CORE EVENT LOOP	2746	=head3 CORE EVENT LOOP
2659		2747
2660	To include only the libev core (all the C<ev_*> functions), with manual	2748	To include only the libev core (all the C<ev_*> functions), with manual
2661	configuration (no autoconf):	2749	configuration (no autoconf):
2662		2750
2663	#define EV_STANDALONE 1	2751	#define EV_STANDALONE 1
2664	#include "ev.c"	2752	#include "ev.c"
2665		2753
2666	This will automatically include F<ev.h>, too, and should be done in a	2754	This will automatically include F<ev.h>, too, and should be done in a
2667	single C source file only to provide the function implementations. To use	2755	single C source file only to provide the function implementations. To use
2668	it, do the same for F<ev.h> in all files wishing to use this API (best	2756	it, do the same for F<ev.h> in all files wishing to use this API (best
2669	done by writing a wrapper around F<ev.h> that you can include instead and	2757	done by writing a wrapper around F<ev.h> that you can include instead and
2670	where you can put other configuration options):	2758	where you can put other configuration options):
2671		2759
2672	#define EV_STANDALONE 1	2760	#define EV_STANDALONE 1
2673	#include "ev.h"	2761	#include "ev.h"
2674		2762
2675	Both header files and implementation files can be compiled with a C++	2763	Both header files and implementation files can be compiled with a C++
2676	compiler (at least, thats a stated goal, and breakage will be treated	2764	compiler (at least, thats a stated goal, and breakage will be treated
2677	as a bug).	2765	as a bug).
2678		2766
2679	You need the following files in your source tree, or in a directory	2767	You need the following files in your source tree, or in a directory
2680	in your include path (e.g. in libev/ when using -Ilibev):	2768	in your include path (e.g. in libev/ when using -Ilibev):
2681		2769
2682	ev.h	2770	ev.h
2683	ev.c	2771	ev.c
2684	ev_vars.h	2772	ev_vars.h
2685	ev_wrap.h	2773	ev_wrap.h
2686		2774
2687	ev_win32.c required on win32 platforms only	2775	ev_win32.c required on win32 platforms only
2688		2776
2689	ev_select.c only when select backend is enabled (which is enabled by default)	2777	ev_select.c only when select backend is enabled (which is enabled by default)
2690	ev_poll.c only when poll backend is enabled (disabled by default)	2778	ev_poll.c only when poll backend is enabled (disabled by default)
2691	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2779	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2692	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2780	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2693	ev_port.c only when the solaris port backend is enabled (disabled by default)	2781	ev_port.c only when the solaris port backend is enabled (disabled by default)
2694		2782
2695	F<ev.c> includes the backend files directly when enabled, so you only need	2783	F<ev.c> includes the backend files directly when enabled, so you only need
2696	to compile this single file.	2784	to compile this single file.
2697		2785
2698	=head3 LIBEVENT COMPATIBILITY API	2786	=head3 LIBEVENT COMPATIBILITY API
2699		2787
2700	To include the libevent compatibility API, also include:	2788	To include the libevent compatibility API, also include:
2701		2789
2702	#include "event.c"	2790	#include "event.c"
2703		2791
2704	in the file including F<ev.c>, and:	2792	in the file including F<ev.c>, and:
2705		2793
2706	#include "event.h"	2794	#include "event.h"
2707		2795
2708	in the files that want to use the libevent API. This also includes F<ev.h>.	2796	in the files that want to use the libevent API. This also includes F<ev.h>.
2709		2797
2710	You need the following additional files for this:	2798	You need the following additional files for this:
2711		2799
2712	event.h	2800	event.h
2713	event.c	2801	event.c
2714		2802
2715	=head3 AUTOCONF SUPPORT	2803	=head3 AUTOCONF SUPPORT
2716		2804
2717	Instead of using C<EV_STANDALONE=1> and providing your config in	2805	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2718	whatever way you want, you can also C<m4_include([libev.m4])> in your	2806	whatever way you want, you can also C<m4_include([libev.m4])> in your
2719	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2807	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2720	include F<config.h> and configure itself accordingly.	2808	include F<config.h> and configure itself accordingly.
2721		2809
2722	For this of course you need the m4 file:	2810	For this of course you need the m4 file:
2723		2811
2724	libev.m4	2812	libev.m4
2725		2813
2726	=head2 PREPROCESSOR SYMBOLS/MACROS	2814	=head2 PREPROCESSOR SYMBOLS/MACROS
2727		2815
2728	Libev can be configured via a variety of preprocessor symbols you have to define	2816	Libev can be configured via a variety of preprocessor symbols you have to
2729	before including any of its files. The default is not to build for multiplicity	2817	define before including any of its files. The default in the absence of
2730	and only include the select backend.	2818	autoconf is noted for every option.
2731		2819
2732	=over 4	2820	=over 4
2733		2821
2734	=item EV_STANDALONE	2822	=item EV_STANDALONE
2735		2823
…		…
2740	F<event.h> that are not directly supported by the libev core alone.	2828	F<event.h> that are not directly supported by the libev core alone.
2741		2829
2742	=item EV_USE_MONOTONIC	2830	=item EV_USE_MONOTONIC
2743		2831
2744	If defined to be C<1>, libev will try to detect the availability of the	2832	If defined to be C<1>, libev will try to detect the availability of the
2745	monotonic clock option at both compiletime and runtime. Otherwise no use	2833	monotonic clock option at both compile time and runtime. Otherwise no use
2746	of the monotonic clock option will be attempted. If you enable this, you	2834	of the monotonic clock option will be attempted. If you enable this, you
2747	usually have to link against librt or something similar. Enabling it when	2835	usually have to link against librt or something similar. Enabling it when
2748	the functionality isn't available is safe, though, although you have	2836	the functionality isn't available is safe, though, although you have
2749	to make sure you link against any libraries where the C<clock_gettime>	2837	to make sure you link against any libraries where the C<clock_gettime>
2750	function is hiding in (often F<-lrt>).	2838	function is hiding in (often F<-lrt>).
2751		2839
2752	=item EV_USE_REALTIME	2840	=item EV_USE_REALTIME
2753		2841
2754	If defined to be C<1>, libev will try to detect the availability of the	2842	If defined to be C<1>, libev will try to detect the availability of the
2755	realtime clock option at compiletime (and assume its availability at	2843	real-time clock option at compile time (and assume its availability at
2756	runtime if successful). Otherwise no use of the realtime clock option will	2844	runtime if successful). Otherwise no use of the real-time clock option will
2757	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2845	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2758	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2846	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2759	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2847	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2760		2848
2761	=item EV_USE_NANOSLEEP	2849	=item EV_USE_NANOSLEEP
2762		2850
2763	If defined to be C<1>, libev will assume that C<nanosleep ()> is available	2851	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
2764	and will use it for delays. Otherwise it will use C<select ()>.	2852	and will use it for delays. Otherwise it will use C<select ()>.
2765		2853
		2854	=item EV_USE_EVENTFD
		2855
		2856	If defined to be C<1>, then libev will assume that C<eventfd ()> is
		2857	available and will probe for kernel support at runtime. This will improve
		2858	C<ev_signal> and C<ev_async> performance and reduce resource consumption.
		2859	If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
		2860	2.7 or newer, otherwise disabled.
		2861
2766	=item EV_USE_SELECT	2862	=item EV_USE_SELECT
2767		2863
2768	If undefined or defined to be C<1>, libev will compile in support for the	2864	If undefined or defined to be C<1>, libev will compile in support for the
2769	C<select>(2) backend. No attempt at autodetection will be done: if no	2865	C<select>(2) backend. No attempt at auto-detection will be done: if no
2770	other method takes over, select will be it. Otherwise the select backend	2866	other method takes over, select will be it. Otherwise the select backend
2771	will not be compiled in.	2867	will not be compiled in.
2772		2868
2773	=item EV_SELECT_USE_FD_SET	2869	=item EV_SELECT_USE_FD_SET
2774		2870
2775	If defined to C<1>, then the select backend will use the system C<fd_set>	2871	If defined to C<1>, then the select backend will use the system C<fd_set>
2776	structure. This is useful if libev doesn't compile due to a missing	2872	structure. This is useful if libev doesn't compile due to a missing
2777	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	2873	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
2778	exotic systems. This usually limits the range of file descriptors to some	2874	exotic systems. This usually limits the range of file descriptors to some
2779	low limit such as 1024 or might have other limitations (winsocket only	2875	low limit such as 1024 or might have other limitations (winsocket only
2780	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	2876	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2781	influence the size of the C<fd_set> used.	2877	influence the size of the C<fd_set> used.
2782		2878
…		…
2806		2902
2807	=item EV_USE_EPOLL	2903	=item EV_USE_EPOLL
2808		2904
2809	If defined to be C<1>, libev will compile in support for the Linux	2905	If defined to be C<1>, libev will compile in support for the Linux
2810	C<epoll>(7) backend. Its availability will be detected at runtime,	2906	C<epoll>(7) backend. Its availability will be detected at runtime,
2811	otherwise another method will be used as fallback. This is the	2907	otherwise another method will be used as fallback. This is the preferred
2812	preferred backend for GNU/Linux systems.	2908	backend for GNU/Linux systems. If undefined, it will be enabled if the
		2909	headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2813		2910
2814	=item EV_USE_KQUEUE	2911	=item EV_USE_KQUEUE
2815		2912
2816	If defined to be C<1>, libev will compile in support for the BSD style	2913	If defined to be C<1>, libev will compile in support for the BSD style
2817	C<kqueue>(2) backend. Its actual availability will be detected at runtime,	2914	C<kqueue>(2) backend. Its actual availability will be detected at runtime,
…		…
2830	otherwise another method will be used as fallback. This is the preferred	2927	otherwise another method will be used as fallback. This is the preferred
2831	backend for Solaris 10 systems.	2928	backend for Solaris 10 systems.
2832		2929
2833	=item EV_USE_DEVPOLL	2930	=item EV_USE_DEVPOLL
2834		2931
2835	reserved for future expansion, works like the USE symbols above.	2932	Reserved for future expansion, works like the USE symbols above.
2836		2933
2837	=item EV_USE_INOTIFY	2934	=item EV_USE_INOTIFY
2838		2935
2839	If defined to be C<1>, libev will compile in support for the Linux inotify	2936	If defined to be C<1>, libev will compile in support for the Linux inotify
2840	interface to speed up C<ev_stat> watchers. Its actual availability will	2937	interface to speed up C<ev_stat> watchers. Its actual availability will
2841	be detected at runtime.	2938	be detected at runtime. If undefined, it will be enabled if the headers
		2939	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2842		2940
2843	=item EV_ATOMIC_T	2941	=item EV_ATOMIC_T
2844		2942
2845	Libev requires an integer type (suitable for storing C<0> or C<1>) whose	2943	Libev requires an integer type (suitable for storing C<0> or C<1>) whose
2846	access is atomic with respect to other threads or signal contexts. No such	2944	access is atomic with respect to other threads or signal contexts. No such
2847	type is easily found in the C language, so you can provide your own type	2945	type is easily found in the C language, so you can provide your own type
2848	that you know is safe for your purposes. It is used both for signal handler "locking"	2946	that you know is safe for your purposes. It is used both for signal handler "locking"
2849	as well as for signal and thread safety in C<ev_async> watchers.	2947	as well as for signal and thread safety in C<ev_async> watchers.
2850		2948
2851	In the absense of this define, libev will use C<sig_atomic_t volatile>	2949	In the absence of this define, libev will use C<sig_atomic_t volatile>
2852	(from F<signal.h>), which is usually good enough on most platforms.	2950	(from F<signal.h>), which is usually good enough on most platforms.
2853		2951
2854	=item EV_H	2952	=item EV_H
2855		2953
2856	The name of the F<ev.h> header file used to include it. The default if	2954	The name of the F<ev.h> header file used to include it. The default if
…		…
2895	When doing priority-based operations, libev usually has to linearly search	2993	When doing priority-based operations, libev usually has to linearly search
2896	all the priorities, so having many of them (hundreds) uses a lot of space	2994	all the priorities, so having many of them (hundreds) uses a lot of space
2897	and time, so using the defaults of five priorities (-2 .. +2) is usually	2995	and time, so using the defaults of five priorities (-2 .. +2) is usually
2898	fine.	2996	fine.
2899		2997
2900	If your embedding app does not need any priorities, defining these both to	2998	If your embedding application does not need any priorities, defining these both to
2901	C<0> will save some memory and cpu.	2999	C<0> will save some memory and CPU.
2902		3000
2903	=item EV_PERIODIC_ENABLE	3001	=item EV_PERIODIC_ENABLE
2904		3002
2905	If undefined or defined to be C<1>, then periodic timers are supported. If	3003	If undefined or defined to be C<1>, then periodic timers are supported. If
2906	defined to be C<0>, then they are not. Disabling them saves a few kB of	3004	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
2933	defined to be C<0>, then they are not.	3031	defined to be C<0>, then they are not.
2934		3032
2935	=item EV_MINIMAL	3033	=item EV_MINIMAL
2936		3034
2937	If you need to shave off some kilobytes of code at the expense of some	3035	If you need to shave off some kilobytes of code at the expense of some
2938	speed, define this symbol to C<1>. Currently only used for gcc to override	3036	speed, define this symbol to C<1>. Currently this is used to override some
2939	some inlining decisions, saves roughly 30% codesize of amd64.	3037	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3038	much smaller 2-heap for timer management over the default 4-heap.
2940		3039
2941	=item EV_PID_HASHSIZE	3040	=item EV_PID_HASHSIZE
2942		3041
2943	C<ev_child> watchers use a small hash table to distribute workload by	3042	C<ev_child> watchers use a small hash table to distribute workload by
2944	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3043	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
…		…
2951	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	3050	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2952	usually more than enough. If you need to manage thousands of C<ev_stat>	3051	usually more than enough. If you need to manage thousands of C<ev_stat>
2953	watchers you might want to increase this value (I<must> be a power of	3052	watchers you might want to increase this value (I<must> be a power of
2954	two).	3053	two).
2955		3054
		3055	=item EV_USE_4HEAP
		3056
		3057	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3058	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3059	to C<1>. The 4-heap uses more complicated (longer) code but has
		3060	noticeably faster performance with many (thousands) of watchers.
		3061
		3062	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3063	(disabled).
		3064
		3065	=item EV_HEAP_CACHE_AT
		3066
		3067	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3068	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3069	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3070	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3071	but avoids random read accesses on heap changes. This improves performance
		3072	noticeably with with many (hundreds) of watchers.
		3073
		3074	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3075	(disabled).
		3076
		3077	=item EV_VERIFY
		3078
		3079	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3080	be done: If set to C<0>, no internal verification code will be compiled
		3081	in. If set to C<1>, then verification code will be compiled in, but not
		3082	called. If set to C<2>, then the internal verification code will be
		3083	called once per loop, which can slow down libev. If set to C<3>, then the
		3084	verification code will be called very frequently, which will slow down
		3085	libev considerably.
		3086
		3087	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3088	C<0.>
		3089
2956	=item EV_COMMON	3090	=item EV_COMMON
2957		3091
2958	By default, all watchers have a C<void *data> member. By redefining	3092	By default, all watchers have a C<void *data> member. By redefining
2959	this macro to a something else you can include more and other types of	3093	this macro to a something else you can include more and other types of
2960	members. You have to define it each time you include one of the files,	3094	members. You have to define it each time you include one of the files,
2961	though, and it must be identical each time.	3095	though, and it must be identical each time.
2962		3096
2963	For example, the perl EV module uses something like this:	3097	For example, the perl EV module uses something like this:
2964		3098
2965	#define EV_COMMON \	3099	#define EV_COMMON \
2966	SV *self; /* contains this struct */ \	3100	SV *self; /* contains this struct */ \
2967	SV *cb_sv, *fh /* note no trailing ";" */	3101	SV *cb_sv, *fh /* note no trailing ";" */
2968		3102
2969	=item EV_CB_DECLARE (type)	3103	=item EV_CB_DECLARE (type)
2970		3104
2971	=item EV_CB_INVOKE (watcher, revents)	3105	=item EV_CB_INVOKE (watcher, revents)
2972		3106
…		…
2979	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3113	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2980	method calls instead of plain function calls in C++.	3114	method calls instead of plain function calls in C++.
2981		3115
2982	=head2 EXPORTED API SYMBOLS	3116	=head2 EXPORTED API SYMBOLS
2983		3117
2984	If you need to re-export the API (e.g. via a dll) and you need a list of	3118	If you need to re-export the API (e.g. via a DLL) and you need a list of
2985	exported symbols, you can use the provided F<Symbol.*> files which list	3119	exported symbols, you can use the provided F<Symbol.*> files which list
2986	all public symbols, one per line:	3120	all public symbols, one per line:
2987		3121
2988	Symbols.ev for libev proper	3122	Symbols.ev for libev proper
2989	Symbols.event for the libevent emulation	3123	Symbols.event for the libevent emulation
2990		3124
2991	This can also be used to rename all public symbols to avoid clashes with	3125	This can also be used to rename all public symbols to avoid clashes with
2992	multiple versions of libev linked together (which is obviously bad in	3126	multiple versions of libev linked together (which is obviously bad in
2993	itself, but sometimes it is inconvinient to avoid this).	3127	itself, but sometimes it is inconvenient to avoid this).
2994		3128
2995	A sed command like this will create wrapper C<#define>'s that you need to	3129	A sed command like this will create wrapper C<#define>'s that you need to
2996	include before including F<ev.h>:	3130	include before including F<ev.h>:
2997		3131
2998	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3132	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3015	file.	3149	file.
3016		3150
3017	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3151	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3018	that everybody includes and which overrides some configure choices:	3152	that everybody includes and which overrides some configure choices:
3019		3153
3020	#define EV_MINIMAL 1	3154	#define EV_MINIMAL 1
3021	#define EV_USE_POLL 0	3155	#define EV_USE_POLL 0
3022	#define EV_MULTIPLICITY 0	3156	#define EV_MULTIPLICITY 0
3023	#define EV_PERIODIC_ENABLE 0	3157	#define EV_PERIODIC_ENABLE 0
3024	#define EV_STAT_ENABLE 0	3158	#define EV_STAT_ENABLE 0
3025	#define EV_FORK_ENABLE 0	3159	#define EV_FORK_ENABLE 0
3026	#define EV_CONFIG_H <config.h>	3160	#define EV_CONFIG_H <config.h>
3027	#define EV_MINPRI 0	3161	#define EV_MINPRI 0
3028	#define EV_MAXPRI 0	3162	#define EV_MAXPRI 0
3029		3163
3030	#include "ev++.h"	3164	#include "ev++.h"
3031		3165
3032	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3166	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3033		3167
3034	#include "ev_cpp.h"	3168	#include "ev_cpp.h"
3035	#include "ev.c"	3169	#include "ev.c"
		3170
		3171
		3172	=head1 THREADS AND COROUTINES
		3173
		3174	=head2 THREADS
		3175
		3176	Libev itself is completely thread-safe, but it uses no locking. This
		3177	means that you can use as many loops as you want in parallel, as long as
		3178	only one thread ever calls into one libev function with the same loop
		3179	parameter.
		3180
		3181	Or put differently: calls with different loop parameters can be done in
		3182	parallel from multiple threads, calls with the same loop parameter must be
		3183	done serially (but can be done from different threads, as long as only one
		3184	thread ever is inside a call at any point in time, e.g. by using a mutex
		3185	per loop).
		3186
		3187	If you want to know which design is best for your problem, then I cannot
		3188	help you but by giving some generic advice:
		3189
		3190	=over 4
		3191
		3192	=item * most applications have a main thread: use the default libev loop
		3193	in that thread, or create a separate thread running only the default loop.
		3194
		3195	This helps integrating other libraries or software modules that use libev
		3196	themselves and don't care/know about threading.
		3197
		3198	=item * one loop per thread is usually a good model.
		3199
		3200	Doing this is almost never wrong, sometimes a better-performance model
		3201	exists, but it is always a good start.
		3202
		3203	=item * other models exist, such as the leader/follower pattern, where one
		3204	loop is handed through multiple threads in a kind of round-robin fashion.
		3205
		3206	Choosing a model is hard - look around, learn, know that usually you can do
		3207	better than you currently do :-)
		3208
		3209	=item * often you need to talk to some other thread which blocks in the
		3210	event loop - C<ev_async> watchers can be used to wake them up from other
		3211	threads safely (or from signal contexts...).
		3212
		3213	=back
		3214
		3215	=head2 COROUTINES
		3216
		3217	Libev is much more accommodating to coroutines ("cooperative threads"):
		3218	libev fully supports nesting calls to it's functions from different
		3219	coroutines (e.g. you can call C<ev_loop> on the same loop from two
		3220	different coroutines and switch freely between both coroutines running the
		3221	loop, as long as you don't confuse yourself). The only exception is that
		3222	you must not do this from C<ev_periodic> reschedule callbacks.
		3223
		3224	Care has been invested into making sure that libev does not keep local
		3225	state inside C<ev_loop>, and other calls do not usually allow coroutine
		3226	switches.
3036		3227
3037		3228
3038	=head1 COMPLEXITIES	3229	=head1 COMPLEXITIES
3039		3230
3040	In this section the complexities of (many of) the algorithms used inside	3231	In this section the complexities of (many of) the algorithms used inside
…		…
3072	correct watcher to remove. The lists are usually short (you don't usually	3263	correct watcher to remove. The lists are usually short (you don't usually
3073	have many watchers waiting for the same fd or signal).	3264	have many watchers waiting for the same fd or signal).
3074		3265
3075	=item Finding the next timer in each loop iteration: O(1)	3266	=item Finding the next timer in each loop iteration: O(1)
3076		3267
3077	By virtue of using a binary heap, the next timer is always found at the	3268	By virtue of using a binary or 4-heap, the next timer is always found at a
3078	beginning of the storage array.	3269	fixed position in the storage array.
3079		3270
3080	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3271	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3081		3272
3082	A change means an I/O watcher gets started or stopped, which requires	3273	A change means an I/O watcher gets started or stopped, which requires
3083	libev to recalculate its status (and possibly tell the kernel, depending	3274	libev to recalculate its status (and possibly tell the kernel, depending
3084	on backend and wether C<ev_io_set> was used).	3275	on backend and whether C<ev_io_set> was used).
3085		3276
3086	=item Activating one watcher (putting it into the pending state): O(1)	3277	=item Activating one watcher (putting it into the pending state): O(1)
3087		3278
3088	=item Priority handling: O(number_of_priorities)	3279	=item Priority handling: O(number_of_priorities)
3089		3280
…		…
3096		3287
3097	=item Processing ev_async_send: O(number_of_async_watchers)	3288	=item Processing ev_async_send: O(number_of_async_watchers)
3098		3289
3099	=item Processing signals: O(max_signal_number)	3290	=item Processing signals: O(max_signal_number)
3100		3291
3101	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3292	Sending involves a system call I<iff> there were no other C<ev_async_send>
3102	calls in the current loop iteration. Checking for async and signal events	3293	calls in the current loop iteration. Checking for async and signal events
3103	involves iterating over all running async watchers or all signal numbers.	3294	involves iterating over all running async watchers or all signal numbers.
3104		3295
3105	=back	3296	=back
3106		3297
3107		3298
3108	=head1 Win32 platform limitations and workarounds	3299	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3109		3300
3110	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3301	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3111	requires, and its I/O model is fundamentally incompatible with the POSIX	3302	requires, and its I/O model is fundamentally incompatible with the POSIX
3112	model. Libev still offers limited functionality on this platform in	3303	model. Libev still offers limited functionality on this platform in
3113	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3304	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3114	descriptors. This only applies when using Win32 natively, not when using	3305	descriptors. This only applies when using Win32 natively, not when using
3115	e.g. cygwin.	3306	e.g. cygwin.
3116		3307
		3308	Lifting these limitations would basically require the full
		3309	re-implementation of the I/O system. If you are into these kinds of
		3310	things, then note that glib does exactly that for you in a very portable
		3311	way (note also that glib is the slowest event library known to man).
		3312
3117	There is no supported compilation method available on windows except	3313	There is no supported compilation method available on windows except
3118	embedding it into other applications.	3314	embedding it into other applications.
3119		3315
		3316	Not a libev limitation but worth mentioning: windows apparently doesn't
		3317	accept large writes: instead of resulting in a partial write, windows will
		3318	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3319	so make sure you only write small amounts into your sockets (less than a
		3320	megabyte seems safe, but thsi apparently depends on the amount of memory
		3321	available).
		3322
3120	Due to the many, low, and arbitrary limits on the win32 platform and the	3323	Due to the many, low, and arbitrary limits on the win32 platform and
3121	abysmal performance of winsockets, using a large number of sockets is not	3324	the abysmal performance of winsockets, using a large number of sockets
3122	recommended (and not reasonable). If your program needs to use more than	3325	is not recommended (and not reasonable). If your program needs to use
3123	a hundred or so sockets, then likely it needs to use a totally different	3326	more than a hundred or so sockets, then likely it needs to use a totally
3124	implementation for windows, as libev offers the POSIX model, which cannot	3327	different implementation for windows, as libev offers the POSIX readiness
3125	be implemented efficiently on windows (microsoft monopoly games).	3328	notification model, which cannot be implemented efficiently on windows
		3329	(Microsoft monopoly games).
		3330
		3331	A typical way to use libev under windows is to embed it (see the embedding
		3332	section for details) and use the following F<evwrap.h> header file instead
		3333	of F<ev.h>:
		3334
		3335	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3336	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3337	#define EV_STAT_ENABLE 0 /* no stat() availble */
		3338
		3339	#include "ev.h"
		3340
		3341	And compile the following F<evwrap.c> file into your project (make sure
		3342	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3343
		3344	#include "evwrap.h"
		3345	#include "ev.c"
3126		3346
3127	=over 4	3347	=over 4
3128		3348
3129	=item The winsocket select function	3349	=item The winsocket select function
3130		3350
3131	The winsocket C<select> function doesn't follow POSIX in that it requires	3351	The winsocket C<select> function doesn't follow POSIX in that it
3132	socket I<handles> and not socket I<file descriptors>. This makes select	3352	requires socket I<handles> and not socket I<file descriptors> (it is
3133	very inefficient, and also requires a mapping from file descriptors	3353	also extremely buggy). This makes select very inefficient, and also
3134	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,	3354	requires a mapping from file descriptors to socket handles (the Microsoft
3135	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor	3355	C runtime provides the function C<_open_osfhandle> for this). See the
3136	symbols for more info.	3356	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3357	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3137		3358
3138	The configuration for a "naked" win32 using the microsoft runtime	3359	The configuration for a "naked" win32 using the Microsoft runtime
3139	libraries and raw winsocket select is:	3360	libraries and raw winsocket select is:
3140		3361
3141	#define EV_USE_SELECT 1	3362	#define EV_USE_SELECT 1
3142	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3363	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3143		3364
3144	Note that winsockets handling of fd sets is O(n), so you can easily get a	3365	Note that winsockets handling of fd sets is O(n), so you can easily get a
3145	complexity in the O(n²) range when using win32.	3366	complexity in the O(n²) range when using win32.
3146		3367
3147	=item Limited number of file descriptors	3368	=item Limited number of file descriptors
3148		3369
3149	Windows has numerous arbitrary (and low) limits on things. Early versions	3370	Windows has numerous arbitrary (and low) limits on things.
3150	of winsocket's select only supported waiting for a max. of C<64> handles	3371
		3372	Early versions of winsocket's select only supported waiting for a maximum
3151	(probably owning to the fact that all windows kernels can only wait for	3373	of C<64> handles (probably owning to the fact that all windows kernels
3152	C<64> things at the same time internally; microsoft recommends spawning a	3374	can only wait for C<64> things at the same time internally; Microsoft
3153	chain of threads and wait for 63 handles and the previous thread in each).	3375	recommends spawning a chain of threads and wait for 63 handles and the
		3376	previous thread in each. Great).
3154		3377
3155	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3378	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3156	to some high number (e.g. C<2048>) before compiling the winsocket select	3379	to some high number (e.g. C<2048>) before compiling the winsocket select
3157	call (which might be in libev or elsewhere, for example, perl does its own	3380	call (which might be in libev or elsewhere, for example, perl does its own
3158	select emulation on windows).	3381	select emulation on windows).
3159		3382
3160	Another limit is the number of file descriptors in the microsoft runtime	3383	Another limit is the number of file descriptors in the Microsoft runtime
3161	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3384	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3162	or something like this inside microsoft). You can increase this by calling	3385	or something like this inside Microsoft). You can increase this by calling
3163	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3386	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3164	arbitrary limit), but is broken in many versions of the microsoft runtime	3387	arbitrary limit), but is broken in many versions of the Microsoft runtime
3165	libraries.	3388	libraries.
3166		3389
3167	This might get you to about C<512> or C<2048> sockets (depending on	3390	This might get you to about C<512> or C<2048> sockets (depending on
3168	windows version and/or the phase of the moon). To get more, you need to	3391	windows version and/or the phase of the moon). To get more, you need to
3169	wrap all I/O functions and provide your own fd management, but the cost of	3392	wrap all I/O functions and provide your own fd management, but the cost of
3170	calling select (O(n²)) will likely make this unworkable.	3393	calling select (O(n²)) will likely make this unworkable.
3171		3394
3172	=back	3395	=back
3173		3396
3174		3397
		3398	=head1 PORTABILITY REQUIREMENTS
		3399
		3400	In addition to a working ISO-C implementation, libev relies on a few
		3401	additional extensions:
		3402
		3403	=over 4
		3404
		3405	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3406	calling conventions regardless of C<ev_watcher_type *>.
		3407
		3408	Libev assumes not only that all watcher pointers have the same internal
		3409	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3410	assumes that the same (machine) code can be used to call any watcher
		3411	callback: The watcher callbacks have different type signatures, but libev
		3412	calls them using an C<ev_watcher *> internally.
		3413
		3414	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3415
		3416	The type C<sig_atomic_t volatile> (or whatever is defined as
		3417	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3418	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3419	believed to be sufficiently portable.
		3420
		3421	=item C<sigprocmask> must work in a threaded environment
		3422
		3423	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3424	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3425	pthread implementations will either allow C<sigprocmask> in the "main
		3426	thread" or will block signals process-wide, both behaviours would
		3427	be compatible with libev. Interaction between C<sigprocmask> and
		3428	C<pthread_sigmask> could complicate things, however.
		3429
		3430	The most portable way to handle signals is to block signals in all threads
		3431	except the initial one, and run the default loop in the initial thread as
		3432	well.
		3433
		3434	=item C<long> must be large enough for common memory allocation sizes
		3435
		3436	To improve portability and simplify using libev, libev uses C<long>
		3437	internally instead of C<size_t> when allocating its data structures. On
		3438	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3439	is still at least 31 bits everywhere, which is enough for hundreds of
		3440	millions of watchers.
		3441
		3442	=item C<double> must hold a time value in seconds with enough accuracy
		3443
		3444	The type C<double> is used to represent timestamps. It is required to
		3445	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3446	enough for at least into the year 4000. This requirement is fulfilled by
		3447	implementations implementing IEEE 754 (basically all existing ones).
		3448
		3449	=back
		3450
		3451	If you know of other additional requirements drop me a note.
		3452
		3453
		3454	=head1 COMPILER WARNINGS
		3455
		3456	Depending on your compiler and compiler settings, you might get no or a
		3457	lot of warnings when compiling libev code. Some people are apparently
		3458	scared by this.
		3459
		3460	However, these are unavoidable for many reasons. For one, each compiler
		3461	has different warnings, and each user has different tastes regarding
		3462	warning options. "Warn-free" code therefore cannot be a goal except when
		3463	targeting a specific compiler and compiler-version.
		3464
		3465	Another reason is that some compiler warnings require elaborate
		3466	workarounds, or other changes to the code that make it less clear and less
		3467	maintainable.
		3468
		3469	And of course, some compiler warnings are just plain stupid, or simply
		3470	wrong (because they don't actually warn about the condition their message
		3471	seems to warn about).
		3472
		3473	While libev is written to generate as few warnings as possible,
		3474	"warn-free" code is not a goal, and it is recommended not to build libev
		3475	with any compiler warnings enabled unless you are prepared to cope with
		3476	them (e.g. by ignoring them). Remember that warnings are just that:
		3477	warnings, not errors, or proof of bugs.
		3478
		3479
		3480	=head1 VALGRIND
		3481
		3482	Valgrind has a special section here because it is a popular tool that is
		3483	highly useful, but valgrind reports are very hard to interpret.
		3484
		3485	If you think you found a bug (memory leak, uninitialised data access etc.)
		3486	in libev, then check twice: If valgrind reports something like:
		3487
		3488	==2274== definitely lost: 0 bytes in 0 blocks.
		3489	==2274== possibly lost: 0 bytes in 0 blocks.
		3490	==2274== still reachable: 256 bytes in 1 blocks.
		3491
		3492	Then there is no memory leak. Similarly, under some circumstances,
		3493	valgrind might report kernel bugs as if it were a bug in libev, or it
		3494	might be confused (it is a very good tool, but only a tool).
		3495
		3496	If you are unsure about something, feel free to contact the mailing list
		3497	with the full valgrind report and an explanation on why you think this is
		3498	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3499	no bug" answer and take the chance of learning how to interpret valgrind
		3500	properly.
		3501
		3502	If you need, for some reason, empty reports from valgrind for your project
		3503	I suggest using suppression lists.
		3504
		3505
3175	=head1 AUTHOR	3506	=head1 AUTHOR
3176		3507
3177	Marc Lehmann <libev@schmorp.de>.	3508	Marc Lehmann <libev@schmorp.de>.
3178		3509

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