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Revision 1.144 by root, Mon Apr 7 12:33:29 2008 UTC vs.
Revision 1.166 by root, Tue Jun 3 03:48:10 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.
…		…
274	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,
275	as loops cannot bes hared easily between threads anyway).	299	as loops cannot bes hared easily between threads anyway).
276		300
277	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
278	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
279	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
280	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
281	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	305	can simply overwrite the C<SIGCHLD> signal handler I<after> calling
282	C<ev_default_init>.	306	C<ev_default_init>.
283		307
284	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
…		…
293	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
294	thing, believe me).	318	thing, believe me).
295		319
296	=item C<EVFLAG_NOENV>	320	=item C<EVFLAG_NOENV>
297		321
298	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
299	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
300	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	324	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
301	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
302	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
303	around bugs.	327	around bugs.
…		…
310		334
311	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,
312	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
313	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
314	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
315	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
316	C<pthread_atfork> which is even faster).	340	C<pthread_atfork> which is even faster).
317		341
318	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
319	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
320	flag.	344	flag.
321		345
322	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>
323	environment variable.	347	environment variable.
324		348
325	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	349	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
326		350
327	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
…		…
329	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
330	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
331	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.
332		356
333	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
334	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
335	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
336	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
337	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
338	readyness notifications you get per iteration.	362	readiness notifications you get per iteration.
339		363
340	=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)
341		365
342	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
343	than select, but handles sparse fds better and has no artificial	367	than select, but handles sparse fds better and has no artificial
…		…
351	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,
352	but it scales phenomenally better. While poll and select usually scale	376	but it scales phenomenally better. While poll and select usually scale
353	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),
354	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
355	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
356	cases and requiring a syscall per fd change, no fork support and bad	380	cases and requiring a system call per fd change, no fork support and bad
357	support for dup.	381	support for dup.
358		382
359	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
360	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
361	(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
362	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
363	very well if you register events for both fds.	387	very well if you register events for both fds.
364		388
365	Please note that epoll sometimes generates spurious notifications, so you	389	Please note that epoll sometimes generates spurious notifications, so you
…		…
368		392
369	Best performance from this backend is achieved by not unregistering all	393	Best performance from this backend is achieved by not unregistering all
370	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.
371	keep at least one watcher active per fd at all times.	395	keep at least one watcher active per fd at all times.
372		396
373	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
374	all kernel versions tested so far.	398	all kernel versions tested so far.
375		399
376	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	400	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
377		401
378	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
379	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
380	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
381	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"
382	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
383	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)
384	system like NetBSD.	408	system like NetBSD.
385		409
386	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
…		…
388	the target platform). See C<ev_embed> watchers for more info.	412	the target platform). See C<ev_embed> watchers for more info.
389		413
390	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
391	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
392	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
393	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
394	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
395	drops fds silently in similarly hard-to-detect cases.	419	drops fds silently in similarly hard-to-detect cases.
396		420
397	This backend usually performs well under most conditions.	421	This backend usually performs well under most conditions.
398		422
…		…
413	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	437	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
414		438
415	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,
416	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)).
417		441
418	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
419	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
420	blocking when no data (or space) is available.	444	blocking when no data (or space) is available.
421		445
422	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
423	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
424	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	448	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
425	might perform better.	449	might perform better.
426		450
427	On the positive side, ignoring the spurious readyness notifications, this	451	On the positive side, ignoring the spurious readiness notifications, this
428	backend actually performed to specification in all tests and is fully	452	backend actually performed to specification in all tests and is fully
429	embeddable, which is a rare feat among the OS-specific backends.	453	embeddable, which is a rare feat among the OS-specific backends.
430		454
431	=item C<EVBACKEND_ALL>	455	=item C<EVBACKEND_ALL>
432		456
…		…
436		460
437	It is definitely not recommended to use this flag.	461	It is definitely not recommended to use this flag.
438		462
439	=back	463	=back
440		464
441	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
442	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
443	specified, all backends in C<ev_recommended_backends ()> will be tried.	467	specified, all backends in C<ev_recommended_backends ()> will be tried.
444		468
445	The most typical usage is like this:	469	The most typical usage is like this:
446		470
447	if (!ev_default_loop (0))	471	if (!ev_default_loop (0))
448	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	472	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
449		473
450	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
451	environment settings to be taken into account:	475	environment settings to be taken into account:
452		476
453	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);	477	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
454		478
455	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
456	available (warning, breaks stuff, best use only with your own private	480	available (warning, breaks stuff, best use only with your own private
457	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):
458		482
459	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	483	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
460		484
461	=item struct ev_loop *ev_loop_new (unsigned int flags)	485	=item struct ev_loop *ev_loop_new (unsigned int flags)
462		486
463	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
464	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
…		…
469	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
470	default loop in the "main" or "initial" thread.	494	default loop in the "main" or "initial" thread.
471		495
472	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.
473		497
474	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	498	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
475	if (!epoller)	499	if (!epoller)
476	fatal ("no epoll found here, maybe it hides under your chair");	500	fatal ("no epoll found here, maybe it hides under your chair");
477		501
478	=item ev_default_destroy ()	502	=item ev_default_destroy ()
479		503
480	Destroys the default loop again (frees all memory and kernel state	504	Destroys the default loop again (frees all memory and kernel state
481	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
482	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
483	responsibility to either stop all watchers cleanly yoursef I<before>	507	responsibility to either stop all watchers cleanly yourself I<before>
484	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
485	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
486	for example).	510	for example).
487		511
488	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
…		…
569	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
570	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
571	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.
572		596
573	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
574	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
575	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
576	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
577	external event in conjunction with something not expressible using other	601	external event in conjunction with something not expressible using other
578	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
579	usually a better approach for this kind of thing.	603	usually a better approach for this kind of thing.
…		…
640	respectively).	664	respectively).
641		665
642	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>
643	running when nothing else is active.	667	running when nothing else is active.
644		668
645	struct ev_signal exitsig;	669	struct ev_signal exitsig;
646	ev_signal_init (&exitsig, sig_cb, SIGINT);	670	ev_signal_init (&exitsig, sig_cb, SIGINT);
647	ev_signal_start (loop, &exitsig);	671	ev_signal_start (loop, &exitsig);
648	evf_unref (loop);	672	evf_unref (loop);
649		673
650	Example: For some weird reason, unregister the above signal handler again.	674	Example: For some weird reason, unregister the above signal handler again.
651		675
652	ev_ref (loop);	676	ev_ref (loop);
653	ev_signal_stop (loop, &exitsig);	677	ev_signal_stop (loop, &exitsig);
654		678
655	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	679	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
656		680
657	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	681	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
658		682
…		…
680	to spend more time collecting timeouts, at the expense of increased	704	to spend more time collecting timeouts, at the expense of increased
681	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
682	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
683	any overhead in libev.	707	any overhead in libev.
684		708
685	Many (busy) programs can usually benefit by setting the io collect	709	Many (busy) programs can usually benefit by setting the I/O collect
686	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
687	interactive servers (of course not for games), likewise for timeouts. It	711	interactive servers (of course not for games), likewise for timeouts. It
688	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>,
689	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.
690		725
691	=back	726	=back
692		727
693		728
694	=head1 ANATOMY OF A WATCHER	729	=head1 ANATOMY OF A WATCHER
695		730
696	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
697	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
698	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:
699		734
700	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)
701	{	736	{
702	ev_io_stop (w);	737	ev_io_stop (w);
703	ev_unloop (loop, EVUNLOOP_ALL);	738	ev_unloop (loop, EVUNLOOP_ALL);
704	}	739	}
705		740
706	struct ev_loop *loop = ev_default_loop (0);	741	struct ev_loop *loop = ev_default_loop (0);
707	struct ev_io stdin_watcher;	742	struct ev_io stdin_watcher;
708	ev_init (&stdin_watcher, my_cb);	743	ev_init (&stdin_watcher, my_cb);
709	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	744	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
710	ev_io_start (loop, &stdin_watcher);	745	ev_io_start (loop, &stdin_watcher);
711	ev_loop (loop, 0);	746	ev_loop (loop, 0);
712		747
713	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
714	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,
715	although this can sometimes be quite valid).	750	although this can sometimes be quite valid).
716		751
717	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
718	(watcher *, callback)>, which expects a callback to be provided. This	753	(watcher *, callback)>, which expects a callback to be provided. This
719	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
720	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
721	is readable and/or writable).	756	is readable and/or writable).
722		757
723	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
724	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
…		…
800		835
801	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>).
802		837
803	=item C<EV_ERROR>	838	=item C<EV_ERROR>
804		839
805	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
806	happen because the watcher could not be properly started because libev	841	happen because the watcher could not be properly started because libev
807	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
808	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
809	with the watcher being stopped.	844	with the watcher being stopped.
810		845
811	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,
812	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
813	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
814	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
815	programs, though, so beware.	850	programs, though, so beware.
816		851
817	=back	852	=back
818		853
819	=head2 GENERIC WATCHER FUNCTIONS	854	=head2 GENERIC WATCHER FUNCTIONS
…		…
849	Although some watcher types do not have type-specific arguments	884	Although some watcher types do not have type-specific arguments
850	(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.
851		886
852	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	887	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
853		888
854	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
855	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
856	a watcher. The same limitations apply, of course.	891	a watcher. The same limitations apply, of course.
857		892
858	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	893	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
859		894
860	Starts (activates) the given watcher. Only active watchers will receive	895	Starts (activates) the given watcher. Only active watchers will receive
…		…
943	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
944	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
945	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
946	data:	981	data:
947		982
948	struct my_io	983	struct my_io
949	{	984	{
950	struct ev_io io;	985	struct ev_io io;
951	int otherfd;	986	int otherfd;
952	void *somedata;	987	void *somedata;
953	struct whatever *mostinteresting;	988	struct whatever *mostinteresting;
954	}	989	}
955		990
956	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
957	can cast it back to your own type:	992	can cast it back to your own type:
958		993
959	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)
960	{	995	{
961	struct my_io *w = (struct my_io *)w_;	996	struct my_io *w = (struct my_io *)w_;
962	...	997	...
963	}	998	}
964		999
965	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
966	instead have been omitted.	1001	instead have been omitted.
967		1002
968	Another common scenario is having some data structure with multiple	1003	Another common scenario is having some data structure with multiple
969	watchers:	1004	watchers:
970		1005
971	struct my_biggy	1006	struct my_biggy
972	{	1007	{
973	int some_data;	1008	int some_data;
974	ev_timer t1;	1009	ev_timer t1;
975	ev_timer t2;	1010	ev_timer t2;
976	}	1011	}
977		1012
978	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,
979	you need to use C<offsetof>:	1014	you need to use C<offsetof>:
980		1015
981	#include <stddef.h>	1016	#include <stddef.h>
982		1017
983	static void	1018	static void
984	t1_cb (EV_P_ struct ev_timer *w, int revents)	1019	t1_cb (EV_P_ struct ev_timer *w, int revents)
985	{	1020	{
986	struct my_biggy big = (struct my_biggy *	1021	struct my_biggy big = (struct my_biggy *
987	(((char *)w) - offsetof (struct my_biggy, t1));	1022	(((char *)w) - offsetof (struct my_biggy, t1));
988	}	1023	}
989		1024
990	static void	1025	static void
991	t2_cb (EV_P_ struct ev_timer *w, int revents)	1026	t2_cb (EV_P_ struct ev_timer *w, int revents)
992	{	1027	{
993	struct my_biggy big = (struct my_biggy *	1028	struct my_biggy big = (struct my_biggy *
994	(((char *)w) - offsetof (struct my_biggy, t2));	1029	(((char *)w) - offsetof (struct my_biggy, t2));
995	}	1030	}
996		1031
997		1032
998	=head1 WATCHER TYPES	1033	=head1 WATCHER TYPES
999		1034
1000	This section describes each watcher in detail, but will not repeat	1035	This section describes each watcher in detail, but will not repeat
…		…
1029	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
1030	(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
1031	C<EVBACKEND_POLL>).	1066	C<EVBACKEND_POLL>).
1032		1067
1033	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
1034	receive "spurious" readyness notifications, that is your callback might	1069	receive "spurious" readiness notifications, that is your callback might
1035	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
1036	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
1037	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
1038	this situation even with a relatively standard program structure. Thus	1073	this situation even with a relatively standard program structure. Thus
1039	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
1040	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.
1041		1076
1042	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
1043	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
1044	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
1045	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
1046	its own, so its quite safe to use).	1081	its own, so its quite safe to use).
1047		1082
1048	=head3 The special problem of disappearing file descriptors	1083	=head3 The special problem of disappearing file descriptors
…		…
1108	=item ev_io_init (ev_io *, callback, int fd, int events)	1143	=item ev_io_init (ev_io *, callback, int fd, int events)
1109		1144
1110	=item ev_io_set (ev_io *, int fd, int events)	1145	=item ev_io_set (ev_io *, int fd, int events)
1111		1146
1112	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
1113	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
1114	C<EV_READ | EV_WRITE> to receive the given events.	1149	C<EV_READ | EV_WRITE> to receive the given events.
1115		1150
1116	=item int fd [read-only]	1151	=item int fd [read-only]
1117		1152
1118	The file descriptor being watched.	1153	The file descriptor being watched.
…		…
1127		1162
1128	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
1129	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
1130	attempt to read a whole line in the callback.	1165	attempt to read a whole line in the callback.
1131		1166
1132	static void	1167	static void
1133	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)
1134	{	1169	{
1135	ev_io_stop (loop, w);	1170	ev_io_stop (loop, w);
1136	.. 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
1137	}	1172	}
1138		1173
1139	...	1174	...
1140	struct ev_loop *loop = ev_default_init (0);	1175	struct ev_loop *loop = ev_default_init (0);
1141	struct ev_io stdin_readable;	1176	struct ev_io stdin_readable;
1142	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);
1143	ev_io_start (loop, &stdin_readable);	1178	ev_io_start (loop, &stdin_readable);
1144	ev_loop (loop, 0);	1179	ev_loop (loop, 0);
1145		1180
1146		1181
1147	=head2 C<ev_timer> - relative and optionally repeating timeouts	1182	=head2 C<ev_timer> - relative and optionally repeating timeouts
1148		1183
1149	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
1150	given time, and optionally repeating in regular intervals after that.	1185	given time, and optionally repeating in regular intervals after that.
1151		1186
1152	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
1153	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
1154	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
1155	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1190	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1156	monotonic clock option helps a lot here).	1191	monotonic clock option helps a lot here).
1157		1192
1158	The relative timeouts are calculated relative to the C<ev_now ()>	1193	The relative timeouts are calculated relative to the C<ev_now ()>
1159	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
…		…
1161	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
1162	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:
1163		1198
1164	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1199	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1165		1200
1166	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,
1167	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
1168	order of execution is undefined.	1203	order of execution is undefined.
1169		1204
1170	=head3 Watcher-Specific Functions and Data Members	1205	=head3 Watcher-Specific Functions and Data Members
1171		1206
…		…
1173		1208
1174	=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)
1175		1210
1176	=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)
1177		1212
1178	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>
1179	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
1180	timer will automatically be configured to trigger again C<repeat> seconds	1215	reached. If it is positive, then the timer will automatically be
1181	later, again, and again, until stopped manually.	1216	configured to trigger again C<repeat> seconds later, again, and again,
		1217	until stopped manually.
1182		1218
1183	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
1184	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
1185	exactly 10 second intervals. If, however, your program cannot keep up with	1221	trigger at exactly 10 second intervals. If, however, your program cannot
1186	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
1187	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.
1188		1224
1189	=item ev_timer_again (loop, ev_timer *)	1225	=item ev_timer_again (loop, ev_timer *)
1190		1226
1191	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
1192	repeating. The exact semantics are:	1228	repeating. The exact semantics are:
1193		1229
1194	If the timer is pending, its pending status is cleared.	1230	If the timer is pending, its pending status is cleared.
1195		1231
1196	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).
1197		1233
1198	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
1199	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.
1200		1236
1201	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
1202	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
1203	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
1204	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
1205	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
1206	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
1207	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
…		…
1233		1269
1234	=head3 Examples	1270	=head3 Examples
1235		1271
1236	Example: Create a timer that fires after 60 seconds.	1272	Example: Create a timer that fires after 60 seconds.
1237		1273
1238	static void	1274	static void
1239	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)
1240	{	1276	{
1241	.. one minute over, w is actually stopped right here	1277	.. one minute over, w is actually stopped right here
1242	}	1278	}
1243		1279
1244	struct ev_timer mytimer;	1280	struct ev_timer mytimer;
1245	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1281	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1246	ev_timer_start (loop, &mytimer);	1282	ev_timer_start (loop, &mytimer);
1247		1283
1248	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
1249	inactivity.	1285	inactivity.
1250		1286
1251	static void	1287	static void
1252	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)
1253	{	1289	{
1254	.. ten seconds without any activity	1290	.. ten seconds without any activity
1255	}	1291	}
1256		1292
1257	struct ev_timer mytimer;	1293	struct ev_timer mytimer;
1258	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 */
1259	ev_timer_again (&mytimer); /* start timer */	1295	ev_timer_again (&mytimer); /* start timer */
1260	ev_loop (loop, 0);	1296	ev_loop (loop, 0);
1261		1297
1262	// 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":
1263	// reset the timeout to start ticking again at 10 seconds	1299	// reset the timeout to start ticking again at 10 seconds
1264	ev_timer_again (&mytimer);	1300	ev_timer_again (&mytimer);
1265		1301
1266		1302
1267	=head2 C<ev_periodic> - to cron or not to cron?	1303	=head2 C<ev_periodic> - to cron or not to cron?
1268		1304
1269	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
1270	(and unfortunately a bit complex).	1306	(and unfortunately a bit complex).
1271		1307
1272	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)
1273	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
1274	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
1275	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 ()
1276	+ 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
1277	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
1278	roughly 10 seconds later).	1315	roughly 10 seconds later as it uses a relative timeout).
1279		1316
1280	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,
1281	triggering an event on each midnight, local time or other, complicated,	1318	such as triggering an event on each "midnight, local time", or other
1282	rules.	1319	complicated, rules.
1283		1320
1284	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
1285	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
1286	during the same loop iteration then order of execution is undefined.	1323	during the same loop iteration then order of execution is undefined.
1287		1324
1288	=head3 Watcher-Specific Functions and Data Members	1325	=head3 Watcher-Specific Functions and Data Members
1289		1326
1290	=over 4	1327	=over 4
…		…
1298		1335
1299	=over 4	1336	=over 4
1300		1337
1301	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1338	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1302		1339
1303	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
1304	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
1305	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
1306	system time reaches or surpasses this time.	1343	run when the system time reaches or surpasses this time.
1307		1344
1308	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1345	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1309		1346
1310	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
1311	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)
1312	and then repeat, regardless of any time jumps.	1349	and then repeat, regardless of any time jumps.
1313		1350
1314	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
1315	time:	1352	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1353	the hour:
1316		1354
1317	ev_periodic_set (&periodic, 0., 3600., 0);	1355	ev_periodic_set (&periodic, 0., 3600., 0);
1318		1356
1319	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,
1320	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
1321	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
1322	by 3600.	1360	by 3600.
1323		1361
1324	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
1325	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
1326	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.
1327		1365
1328	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
1329	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
1330	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).
1331		1374
1332	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1375	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1333		1376
1334	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
1335	ignored. Instead, each time the periodic watcher gets scheduled, the	1378	ignored. Instead, each time the periodic watcher gets scheduled, the
1336	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
1337	current time as second argument.	1380	current time as second argument.
1338		1381
1339	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,
1340	ever, or make any event loop modifications>. If you need to stop it,	1383	ever, or make ANY event loop modifications whatsoever>.
1341	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1342	starting an C<ev_prepare> watcher, which is legal).
1343		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
1344	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
1345	ev_tstamp now)>, e.g.:	1390	*w, ev_tstamp now)>, e.g.:
1346		1391
1347	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)
1348	{	1393	{
1349	return now + 60.;	1394	return now + 60.;
1350	}	1395	}
…		…
1352	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
1353	(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
1354	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
1355	might be called at other times, too.	1400	might be called at other times, too.
1356		1401
1357	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
1358	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.	1403	equal to the passed C<now> value >>.
1359		1404
1360	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
1361	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
1362	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
1363	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
1364	reason I omitted it as an example).	1409	reason I omitted it as an example).
1365		1410
1366	=back	1411	=back
…		…
1370	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
1371	when you changed some parameters or the reschedule callback would return	1416	when you changed some parameters or the reschedule callback would return
1372	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
1373	program when the crontabs have changed).	1418	program when the crontabs have changed).
1374		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
1375	=item ev_tstamp offset [read-write]	1425	=item ev_tstamp offset [read-write]
1376		1426
1377	When repeating, this contains the offset value, otherwise this is the	1427	When repeating, this contains the offset value, otherwise this is the
1378	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>).
1379		1429
…		…
1390		1440
1391	The current reschedule callback, or C<0>, if this functionality is	1441	The current reschedule callback, or C<0>, if this functionality is
1392	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
1393	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.
1394		1444
1395	=item ev_tstamp at [read-only]
1396
1397	When active, contains the absolute time that the watcher is supposed to
1398	trigger next.
1399
1400	=back	1445	=back
1401		1446
1402	=head3 Examples	1447	=head3 Examples
1403		1448
1404	Example: Call a callback every hour, or, more precisely, whenever the	1449	Example: Call a callback every hour, or, more precisely, whenever the
1405	system clock is divisible by 3600. The callback invocation times have	1450	system clock is divisible by 3600. The callback invocation times have
1406	potentially a lot of jittering, but good long-term stability.	1451	potentially a lot of jitter, but good long-term stability.
1407		1452
1408	static void	1453	static void
1409	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)
1410	{	1455	{
1411	... 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)
1412	}	1457	}
1413		1458
1414	struct ev_periodic hourly_tick;	1459	struct ev_periodic hourly_tick;
1415	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1460	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1416	ev_periodic_start (loop, &hourly_tick);	1461	ev_periodic_start (loop, &hourly_tick);
1417		1462
1418	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:
1419		1464
1420	#include <math.h>	1465	#include <math.h>
1421		1466
1422	static ev_tstamp	1467	static ev_tstamp
1423	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1468	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1424	{	1469	{
1425	return fmod (now, 3600.) + 3600.;	1470	return fmod (now, 3600.) + 3600.;
1426	}	1471	}
1427		1472
1428	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);
1429		1474
1430	Example: Call a callback every hour, starting now:	1475	Example: Call a callback every hour, starting now:
1431		1476
1432	struct ev_periodic hourly_tick;	1477	struct ev_periodic hourly_tick;
1433	ev_periodic_init (&hourly_tick, clock_cb,	1478	ev_periodic_init (&hourly_tick, clock_cb,
1434	fmod (ev_now (loop), 3600.), 3600., 0);	1479	fmod (ev_now (loop), 3600.), 3600., 0);
1435	ev_periodic_start (loop, &hourly_tick);	1480	ev_periodic_start (loop, &hourly_tick);
1436		1481
1437		1482
1438	=head2 C<ev_signal> - signal me when a signal gets signalled!	1483	=head2 C<ev_signal> - signal me when a signal gets signalled!
1439		1484
1440	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
…		…
1448	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
1449	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
1450	SIG_DFL (regardless of what it was set to before).	1495	SIG_DFL (regardless of what it was set to before).
1451		1496
1452	If possible and supported, libev will install its handlers with	1497	If possible and supported, libev will install its handlers with
1453	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1498	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1454	interrupted. If you have a problem with syscalls getting interrupted by	1499	interrupted. If you have a problem with system calls getting interrupted by
1455	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
1456	them in an C<ev_prepare> watcher.	1501	them in an C<ev_prepare> watcher.
1457		1502
1458	=head3 Watcher-Specific Functions and Data Members	1503	=head3 Watcher-Specific Functions and Data Members
1459		1504
…		…
1474		1519
1475	=head3 Examples	1520	=head3 Examples
1476		1521
1477	Example: Try to exit cleanly on SIGINT and SIGTERM.	1522	Example: Try to exit cleanly on SIGINT and SIGTERM.
1478		1523
1479	static void	1524	static void
1480	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)
1481	{	1526	{
1482	ev_unloop (loop, EVUNLOOP_ALL);	1527	ev_unloop (loop, EVUNLOOP_ALL);
1483	}	1528	}
1484		1529
1485	struct ev_signal signal_watcher;	1530	struct ev_signal signal_watcher;
1486	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1531	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1487	ev_signal_start (loop, &sigint_cb);	1532	ev_signal_start (loop, &sigint_cb);
1488		1533
1489		1534
1490	=head2 C<ev_child> - watch out for process status changes	1535	=head2 C<ev_child> - watch out for process status changes
1491		1536
1492	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
…		…
1494	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
1495	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
1496	loop isn't entered (or is continued from a watcher).	1541	loop isn't entered (or is continued from a watcher).
1497		1542
1498	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
1499	you can only rgeister child watchers in the default event loop.	1544	you can only register child watchers in the default event loop.
1500		1545
1501	=head3 Process Interaction	1546	=head3 Process Interaction
1502		1547
1503	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
1504	initialised. This is necessary to guarantee proper behaviour even if	1549	initialised. This is necessary to guarantee proper behaviour even if
1505	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
1506	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1551	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1507	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
1508	children, even ones not watched.	1553	children, even ones not watched.
1509		1554
1510	=head3 Overriding the Built-In Processing	1555	=head3 Overriding the Built-In Processing
…		…
1552	=head3 Examples	1597	=head3 Examples
1553		1598
1554	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
1555	its completion.	1600	its completion.
1556		1601
1557	ev_child cw;	1602	ev_child cw;
1558		1603
1559	static void	1604	static void
1560	child_cb (EV_P_ struct ev_child *w, int revents)	1605	child_cb (EV_P_ struct ev_child *w, int revents)
1561	{	1606	{
1562	ev_child_stop (EV_A_ w);	1607	ev_child_stop (EV_A_ w);
1563	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);
1564	}	1609	}
1565		1610
1566	pid_t pid = fork ();	1611	pid_t pid = fork ();
1567		1612
1568	if (pid < 0)	1613	if (pid < 0)
1569	// error	1614	// error
1570	else if (pid == 0)	1615	else if (pid == 0)
1571	{	1616	{
1572	// the forked child executes here	1617	// the forked child executes here
1573	exit (1);	1618	exit (1);
1574	}	1619	}
1575	else	1620	else
1576	{	1621	{
1577	ev_child_init (&cw, child_cb, pid, 0);	1622	ev_child_init (&cw, child_cb, pid, 0);
1578	ev_child_start (EV_DEFAULT_ &cw);	1623	ev_child_start (EV_DEFAULT_ &cw);
1579	}	1624	}
1580		1625
1581		1626
1582	=head2 C<ev_stat> - did the file attributes just change?	1627	=head2 C<ev_stat> - did the file attributes just change?
1583		1628
1584	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
1585	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
1586	compared to the last time, invoking the callback if it did.	1631	compared to the last time, invoking the callback if it did.
1587		1632
1588	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
1589	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
…		…
1607	as even with OS-supported change notifications, this can be	1652	as even with OS-supported change notifications, this can be
1608	resource-intensive.	1653	resource-intensive.
1609		1654
1610	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
1611	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
1612	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
1613	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
1614	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,
1615	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
1616	polling.	1662	will be no polling.
1617		1663
1618	=head3 ABI Issues (Largefile Support)	1664	=head3 ABI Issues (Largefile Support)
1619		1665
1620	Libev by default (unless the user overrides this) uses the default	1666	Libev by default (unless the user overrides this) uses the default
1621	compilation environment, which means that on systems with optionally	1667	compilation environment, which means that on systems with optionally
1622	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
1623	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
1624	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
1625	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
1626	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
1627	most noticably with ev_stat and largefile support.	1673	most noticeably with ev_stat and large file support.
1628		1674
1629	=head3 Inotify	1675	=head3 Inotify
1630		1676
1631	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
1632	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
1633	change detection where possible. The inotify descriptor will be created lazily	1679	change detection where possible. The inotify descriptor will be created lazily
1634	when the first C<ev_stat> watcher is being started.	1680	when the first C<ev_stat> watcher is being started.
1635		1681
1636	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
1637	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
1638	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
1639	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.
1640		1686
1641	(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
1642	implement this functionality, due to the requirement of having a file	1688	implement this functionality, due to the requirement of having a file
1643	descriptor open on the object at all times).	1689	descriptor open on the object at all times).
1644		1690
1645	=head3 The special problem of stat time resolution	1691	=head3 The special problem of stat time resolution
1646		1692
1647	The C<stat ()> syscall only supports full-second resolution portably, and	1693	The C<stat ()> system call only supports full-second resolution portably, and
1648	even on systems where the resolution is higher, many filesystems still	1694	even on systems where the resolution is higher, many file systems still
1649	only support whole seconds.	1695	only support whole seconds.
1650		1696
1651	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
1652	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
1653	your callback, which does something. When there is another update within	1699	calls your callback, which does something. When there is another update
1654	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.
1655		1702
1656	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
1657	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
1658	(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);
1659	is added to work around small timing inconsistencies of some operating	1706	ev_timer_again (loop, w)>).
1660	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).
1661		1716
1662	=head3 Watcher-Specific Functions and Data Members	1717	=head3 Watcher-Specific Functions and Data Members
1663		1718
1664	=over 4	1719	=over 4
1665		1720
…		…
1671	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
1672	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
1673	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
1674	path for as long as the watcher is active.	1729	path for as long as the watcher is active.
1675		1730
1676	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
1677	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
1678	last change was detected).	1733	was detected).
1679		1734
1680	=item ev_stat_stat (loop, ev_stat *)	1735	=item ev_stat_stat (loop, ev_stat *)
1681		1736
1682	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
1683	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
1684	detecting this change (while introducing a race condition). Can also be	1739	detecting this change (while introducing a race condition if you are not
1685	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.
1686		1742
1687	=item ev_statdata attr [read-only]	1743	=item ev_statdata attr [read-only]
1688		1744
1689	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
1690	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
1691	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
1692	was some error while C<stat>ing the file.	1749	some error while C<stat>ing the file.
1693		1750
1694	=item ev_statdata prev [read-only]	1751	=item ev_statdata prev [read-only]
1695		1752
1696	The previous attributes of the file. The callback gets invoked whenever	1753	The previous attributes of the file. The callback gets invoked whenever
1697	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>.
1698		1757
1699	=item ev_tstamp interval [read-only]	1758	=item ev_tstamp interval [read-only]
1700		1759
1701	The specified interval.	1760	The specified interval.
1702		1761
1703	=item const char *path [read-only]	1762	=item const char *path [read-only]
1704		1763
1705	The filesystem path that is being watched.	1764	The file system path that is being watched.
1706		1765
1707	=back	1766	=back
1708		1767
1709	=head3 Examples	1768	=head3 Examples
1710		1769
1711	Example: Watch C</etc/passwd> for attribute changes.	1770	Example: Watch C</etc/passwd> for attribute changes.
1712		1771
1713	static void	1772	static void
1714	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1773	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1715	{	1774	{
1716	/* /etc/passwd changed in some way */	1775	/* /etc/passwd changed in some way */
1717	if (w->attr.st_nlink)	1776	if (w->attr.st_nlink)
1718	{	1777	{
1719	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1778	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1720	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1779	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1721	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1780	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1722	}	1781	}
1723	else	1782	else
1724	/* you shalt not abuse printf for puts */	1783	/* you shalt not abuse printf for puts */
1725	puts ("wow, /etc/passwd is not there, expect problems. "	1784	puts ("wow, /etc/passwd is not there, expect problems. "
1726	"if this is windows, they already arrived\n");	1785	"if this is windows, they already arrived\n");
1727	}	1786	}
1728		1787
1729	...	1788	...
1730	ev_stat passwd;	1789	ev_stat passwd;
1731		1790
1732	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1791	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1733	ev_stat_start (loop, &passwd);	1792	ev_stat_start (loop, &passwd);
1734		1793
1735	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
1736	miss updates (however, frequent updates will delay processing, too, so	1795	miss updates (however, frequent updates will delay processing, too, so
1737	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
1738	C<ev_timer> callback invocation).	1797	C<ev_timer> callback invocation).
1739		1798
1740	static ev_stat passwd;	1799	static ev_stat passwd;
1741	static ev_timer timer;	1800	static ev_timer timer;
1742		1801
1743	static void	1802	static void
1744	timer_cb (EV_P_ ev_timer *w, int revents)	1803	timer_cb (EV_P_ ev_timer *w, int revents)
1745	{	1804	{
1746	ev_timer_stop (EV_A_ w);	1805	ev_timer_stop (EV_A_ w);
1747		1806
1748	/* now it's one second after the most recent passwd change */	1807	/* now it's one second after the most recent passwd change */
1749	}	1808	}
1750		1809
1751	static void	1810	static void
1752	stat_cb (EV_P_ ev_stat *w, int revents)	1811	stat_cb (EV_P_ ev_stat *w, int revents)
1753	{	1812	{
1754	/* reset the one-second timer */	1813	/* reset the one-second timer */
1755	ev_timer_again (EV_A_ &timer);	1814	ev_timer_again (EV_A_ &timer);
1756	}	1815	}
1757		1816
1758	...	1817	...
1759	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1818	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1760	ev_stat_start (loop, &passwd);	1819	ev_stat_start (loop, &passwd);
1761	ev_timer_init (&timer, timer_cb, 0., 1.01);	1820	ev_timer_init (&timer, timer_cb, 0., 1.02);
1762		1821
1763		1822
1764	=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...
1765		1824
1766	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
…		…
1797	=head3 Examples	1856	=head3 Examples
1798		1857
1799	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
1800	callback, free it. Also, use no error checking, as usual.	1859	callback, free it. Also, use no error checking, as usual.
1801		1860
1802	static void	1861	static void
1803	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)
1804	{	1863	{
1805	free (w);	1864	free (w);
1806	// now do something you wanted to do when the program has	1865	// now do something you wanted to do when the program has
1807	// no longer anything immediate to do.	1866	// no longer anything immediate to do.
1808	}	1867	}
1809		1868
1810	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1869	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1811	ev_idle_init (idle_watcher, idle_cb);	1870	ev_idle_init (idle_watcher, idle_cb);
1812	ev_idle_start (loop, idle_cb);	1871	ev_idle_start (loop, idle_cb);
1813		1872
1814		1873
1815	=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!
1816		1875
1817	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:
…		…
1836		1895
1837	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
1838	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
1839	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
1840	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
1841	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
1842	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
1843	callbacks will never actually be called (but must be valid nevertheless,	1902	callbacks will never actually be called (but must be valid nevertheless,
1844	because you never know, you know?).	1903	because you never know, you know?).
1845		1904
1846	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
…		…
1854		1913
1855	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>)
1856	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
1857	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,
1858	too) should not activate ("feed") events into libev. While libev fully	1917	too) should not activate ("feed") events into libev. While libev fully
1859	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
1860	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
1861	(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
1862	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
1863	coexist peacefully with others).	1922	coexist peacefully with others).
1864		1923
…		…
1879	=head3 Examples	1938	=head3 Examples
1880		1939
1881	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
1882	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
1883	(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
1884	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
1885	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
1886	into the Glib event loop).	1945	Glib event loop).
1887		1946
1888	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,
1889	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
1890	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
1891	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
1892	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.
1893		1952
1894	static ev_io iow [nfd];	1953	static ev_io iow [nfd];
1895	static ev_timer tw;	1954	static ev_timer tw;
1896		1955
1897	static void	1956	static void
1898	io_cb (ev_loop *loop, ev_io *w, int revents)	1957	io_cb (ev_loop *loop, ev_io *w, int revents)
1899	{	1958	{
1900	}	1959	}
1901		1960
1902	// create io watchers for each fd and a timer before blocking	1961	// create io watchers for each fd and a timer before blocking
1903	static void	1962	static void
1904	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1963	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1905	{	1964	{
1906	int timeout = 3600000;	1965	int timeout = 3600000;
1907	struct pollfd fds [nfd];	1966	struct pollfd fds [nfd];
1908	// actual code will need to loop here and realloc etc.	1967	// actual code will need to loop here and realloc etc.
1909	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1968	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1910		1969
1911	/* 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 */
1912	ev_timer_init (&tw, 0, timeout * 1e-3);	1971	ev_timer_init (&tw, 0, timeout * 1e-3);
1913	ev_timer_start (loop, &tw);	1972	ev_timer_start (loop, &tw);
1914		1973
1915	// create one ev_io per pollfd	1974	// create one ev_io per pollfd
1916	for (int i = 0; i < nfd; ++i)	1975	for (int i = 0; i < nfd; ++i)
1917	{	1976	{
1918	ev_io_init (iow + i, io_cb, fds [i].fd,	1977	ev_io_init (iow + i, io_cb, fds [i].fd,
1919	((fds [i].events & POLLIN ? EV_READ : 0)	1978	((fds [i].events & POLLIN ? EV_READ : 0)
1920	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1979	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1921		1980
1922	fds [i].revents = 0;	1981	fds [i].revents = 0;
1923	ev_io_start (loop, iow + i);	1982	ev_io_start (loop, iow + i);
1924	}	1983	}
1925	}	1984	}
1926		1985
1927	// stop all watchers after blocking	1986	// stop all watchers after blocking
1928	static void	1987	static void
1929	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1988	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1930	{	1989	{
1931	ev_timer_stop (loop, &tw);	1990	ev_timer_stop (loop, &tw);
1932		1991
1933	for (int i = 0; i < nfd; ++i)	1992	for (int i = 0; i < nfd; ++i)
1934	{	1993	{
1935	// set the relevant poll flags	1994	// set the relevant poll flags
1936	// could also call adns_processreadable etc. here	1995	// could also call adns_processreadable etc. here
1937	struct pollfd *fd = fds + i;	1996	struct pollfd *fd = fds + i;
1938	int revents = ev_clear_pending (iow + i);	1997	int revents = ev_clear_pending (iow + i);
1939	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	1998	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1940	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	1999	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1941		2000
1942	// now stop the watcher	2001	// now stop the watcher
1943	ev_io_stop (loop, iow + i);	2002	ev_io_stop (loop, iow + i);
1944	}	2003	}
1945		2004
1946	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2005	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1947	}	2006	}
1948		2007
1949	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>
1950	in the prepare watcher and would dispose of the check watcher.	2009	in the prepare watcher and would dispose of the check watcher.
1951		2010
1952	Method 3: If the module to be embedded supports explicit event	2011	Method 3: If the module to be embedded supports explicit event
1953	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
1954	callbacks, and only destroy/create the watchers in the prepare watcher.	2013	callbacks, and only destroy/create the watchers in the prepare watcher.
1955		2014
1956	static void	2015	static void
1957	timer_cb (EV_P_ ev_timer *w, int revents)	2016	timer_cb (EV_P_ ev_timer *w, int revents)
1958	{	2017	{
1959	adns_state ads = (adns_state)w->data;	2018	adns_state ads = (adns_state)w->data;
1960	update_now (EV_A);	2019	update_now (EV_A);
1961		2020
1962	adns_processtimeouts (ads, &tv_now);	2021	adns_processtimeouts (ads, &tv_now);
1963	}	2022	}
1964		2023
1965	static void	2024	static void
1966	io_cb (EV_P_ ev_io *w, int revents)	2025	io_cb (EV_P_ ev_io *w, int revents)
1967	{	2026	{
1968	adns_state ads = (adns_state)w->data;	2027	adns_state ads = (adns_state)w->data;
1969	update_now (EV_A);	2028	update_now (EV_A);
1970		2029
1971	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2030	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1972	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2031	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1973	}	2032	}
1974		2033
1975	// do not ever call adns_afterpoll	2034	// do not ever call adns_afterpoll
1976		2035
1977	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
1978	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
1979	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
1980	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
1981	this.	2040	this.
1982		2041
1983	static gint	2042	static gint
1984	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2043	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1985	{	2044	{
1986	int got_events = 0;	2045	int got_events = 0;
1987		2046
1988	for (n = 0; n < nfds; ++n)	2047	for (n = 0; n < nfds; ++n)
1989	// 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
1990		2049
1991	if (timeout >= 0)	2050	if (timeout >= 0)
1992	// create/start timer	2051	// create/start timer
1993		2052
1994	// poll	2053	// poll
1995	ev_loop (EV_A_ 0);	2054	ev_loop (EV_A_ 0);
1996		2055
1997	// stop timer again	2056	// stop timer again
1998	if (timeout >= 0)	2057	if (timeout >= 0)
1999	ev_timer_stop (EV_A_ &to);	2058	ev_timer_stop (EV_A_ &to);
2000		2059
2001	// stop io watchers again - their callbacks should have set	2060	// stop io watchers again - their callbacks should have set
2002	for (n = 0; n < nfds; ++n)	2061	for (n = 0; n < nfds; ++n)
2003	ev_io_stop (EV_A_ iow [n]);	2062	ev_io_stop (EV_A_ iow [n]);
2004		2063
2005	return got_events;	2064	return got_events;
2006	}	2065	}
2007		2066
2008		2067
2009	=head2 C<ev_embed> - when one backend isn't enough...	2068	=head2 C<ev_embed> - when one backend isn't enough...
2010		2069
2011	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
…		…
2067		2126
2068	Configures the watcher to embed the given loop, which must be	2127	Configures the watcher to embed the given loop, which must be
2069	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
2070	invoked automatically, otherwise it is the responsibility of the callback	2129	invoked automatically, otherwise it is the responsibility of the callback
2071	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,
2072	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).
2073		2132
2074	=item ev_embed_sweep (loop, ev_embed *)	2133	=item ev_embed_sweep (loop, ev_embed *)
2075		2134
2076	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
2077	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
2078	apropriate way for embedded loops.	2137	appropriate way for embedded loops.
2079		2138
2080	=item struct ev_loop *other [read-only]	2139	=item struct ev_loop *other [read-only]
2081		2140
2082	The embedded event loop.	2141	The embedded event loop.
2083		2142
…		…
2085		2144
2086	=head3 Examples	2145	=head3 Examples
2087		2146
2088	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
2089	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
2090	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
2091	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
2092	used).	2151	used).
2093		2152
2094	struct ev_loop *loop_hi = ev_default_init (0);	2153	struct ev_loop *loop_hi = ev_default_init (0);
2095	struct ev_loop *loop_lo = 0;	2154	struct ev_loop *loop_lo = 0;
2096	struct ev_embed embed;	2155	struct ev_embed embed;
2097		2156
2098	// see if there is a chance of getting one that works	2157	// see if there is a chance of getting one that works
2099	// (remember that a flags value of 0 means autodetection)	2158	// (remember that a flags value of 0 means autodetection)
2100	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2159	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2101	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2160	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2102	: 0;	2161	: 0;
2103		2162
2104	// 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
2105	if (loop_lo)	2164	if (loop_lo)
2106	{	2165	{
2107	ev_embed_init (&embed, 0, loop_lo);	2166	ev_embed_init (&embed, 0, loop_lo);
2108	ev_embed_start (loop_hi, &embed);	2167	ev_embed_start (loop_hi, &embed);
2109	}	2168	}
2110	else	2169	else
2111	loop_lo = loop_hi;	2170	loop_lo = loop_hi;
2112		2171
2113	Example: Check if kqueue is available but not recommended and create	2172	Example: Check if kqueue is available but not recommended and create
2114	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
2115	kqueue implementation). Store the kqueue/socket-only event loop in	2174	kqueue implementation). Store the kqueue/socket-only event loop in
2116	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2175	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2117		2176
2118	struct ev_loop *loop = ev_default_init (0);	2177	struct ev_loop *loop = ev_default_init (0);
2119	struct ev_loop *loop_socket = 0;	2178	struct ev_loop *loop_socket = 0;
2120	struct ev_embed embed;	2179	struct ev_embed embed;
2121		2180
2122	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2181	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2123	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2182	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2124	{	2183	{
2125	ev_embed_init (&embed, 0, loop_socket);	2184	ev_embed_init (&embed, 0, loop_socket);
2126	ev_embed_start (loop, &embed);	2185	ev_embed_start (loop, &embed);
2127	}	2186	}
2128		2187
2129	if (!loop_socket)	2188	if (!loop_socket)
2130	loop_socket = loop;	2189	loop_socket = loop;
2131		2190
2132	// 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
2133		2192
2134		2193
2135	=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
2136		2195
2137	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
…		…
2190		2249
2191	=item queueing from a signal handler context	2250	=item queueing from a signal handler context
2192		2251
2193	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
2194	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
2195	some fictitiuous SIGUSR1 handler:	2254	some fictitious SIGUSR1 handler:
2196		2255
2197	static ev_async mysig;	2256	static ev_async mysig;
2198		2257
2199	static void	2258	static void
2200	sigusr1_handler (void)	2259	sigusr1_handler (void)
…		…
2274	=item ev_async_send (loop, ev_async *)	2333	=item ev_async_send (loop, ev_async *)
2275		2334
2276	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
2277	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
2278	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
2279	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
2280	section below on what exactly this means).	2339	section below on what exactly this means).
2281		2340
2282	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,
2283	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
2284	calls to C<ev_async_send>.	2343	calls to C<ev_async_send>.
2285		2344
2286	=item bool = ev_async_pending (ev_async *)	2345	=item bool = ev_async_pending (ev_async *)
2287		2346
2288	Returns a non-zero value when C<ev_async_send> has been called on the	2347	Returns a non-zero value when C<ev_async_send> has been called on the
…		…
2290	event loop.	2349	event loop.
2291		2350
2292	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When	2351	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
2293	the loop iterates next and checks for the watcher to have become active,	2352	the loop iterates next and checks for the watcher to have become active,
2294	it will reset the flag again. C<ev_async_pending> can be used to very	2353	it will reset the flag again. C<ev_async_pending> can be used to very
2295	quickly check wether invoking the loop might be a good idea.	2354	quickly check whether invoking the loop might be a good idea.
2296		2355
2297	Not that this does I<not> check wether the watcher itself is pending, only	2356	Not that this does I<not> check whether the watcher itself is pending, only
2298	wether it has been requested to make this watcher pending.	2357	whether it has been requested to make this watcher pending.
2299		2358
2300	=back	2359	=back
2301		2360
2302		2361
2303	=head1 OTHER FUNCTIONS	2362	=head1 OTHER FUNCTIONS
…		…
2314	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
2315	more watchers yourself.	2374	more watchers yourself.
2316		2375
2317	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
2318	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
2319	C<events> set will be craeted and started.	2378	C<events> set will be created and started.
2320		2379
2321	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
2322	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
2323	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
2324	dubious value.	2383	dubious value.
…		…
2326	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
2327	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
2328	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>
2329	value passed to C<ev_once>:	2388	value passed to C<ev_once>:
2330		2389
2331	static void stdin_ready (int revents, void *arg)	2390	static void stdin_ready (int revents, void *arg)
2332	{	2391	{
2333	if (revents & EV_TIMEOUT)	2392	if (revents & EV_TIMEOUT)
2334	/* doh, nothing entered */;	2393	/* doh, nothing entered */;
2335	else if (revents & EV_READ)	2394	else if (revents & EV_READ)
2336	/* stdin might have data for us, joy! */;	2395	/* stdin might have data for us, joy! */;
2337	}	2396	}
2338		2397
2339	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2398	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2340		2399
2341	=item ev_feed_event (ev_loop *, watcher *, int revents)	2400	=item ev_feed_event (ev_loop *, watcher *, int revents)
2342		2401
2343	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
2344	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
…		…
2349	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
2350	the given events it.	2409	the given events it.
2351		2410
2352	=item ev_feed_signal_event (ev_loop *loop, int signum)	2411	=item ev_feed_signal_event (ev_loop *loop, int signum)
2353		2412
2354	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
2355	loop!).	2414	loop!).
2356		2415
2357	=back	2416	=back
2358		2417
2359		2418
…		…
2375		2434
2376	=item * Priorities are not currently supported. Initialising priorities	2435	=item * Priorities are not currently supported. Initialising priorities
2377	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
2378	is an ev_pri field.	2437	is an ev_pri field.
2379		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
2380	=item * Other members are not supported.	2442	=item * Other members are not supported.
2381		2443
2382	=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
2383	to use the libev header file and library.	2445	to use the libev header file and library.
2384		2446
2385	=back	2447	=back
2386		2448
2387	=head1 C++ SUPPORT	2449	=head1 C++ SUPPORT
2388		2450
2389	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
2390	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
2391	the callback model to a model using method callbacks on objects.	2453	the callback model to a model using method callbacks on objects.
2392		2454
2393	To use it,	2455	To use it,
2394		2456
2395	#include <ev++.h>	2457	#include <ev++.h>
2396		2458
2397	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
2398	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
2399	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
2400	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2462	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2467	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
2468	thunking function, making it as fast as a direct C callback.	2530	thunking function, making it as fast as a direct C callback.
2469		2531
2470	Example: simple class declaration and watcher initialisation	2532	Example: simple class declaration and watcher initialisation
2471		2533
2472	struct myclass	2534	struct myclass
2473	{	2535	{
2474	void io_cb (ev::io &w, int revents) { }	2536	void io_cb (ev::io &w, int revents) { }
2475	}	2537	}
2476		2538
2477	myclass obj;	2539	myclass obj;
2478	ev::io iow;	2540	ev::io iow;
2479	iow.set <myclass, &myclass::io_cb> (&obj);	2541	iow.set <myclass, &myclass::io_cb> (&obj);
2480		2542
2481	=item w->set<function> (void *data = 0)	2543	=item w->set<function> (void *data = 0)
2482		2544
2483	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
2484	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
…		…
2488		2550
2489	See the method-C<set> above for more details.	2551	See the method-C<set> above for more details.
2490		2552
2491	Example:	2553	Example:
2492		2554
2493	static void io_cb (ev::io &w, int revents) { }	2555	static void io_cb (ev::io &w, int revents) { }
2494	iow.set <io_cb> ();	2556	iow.set <io_cb> ();
2495		2557
2496	=item w->set (struct ev_loop *)	2558	=item w->set (struct ev_loop *)
2497		2559
2498	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
2499	do this when the watcher is inactive (and not pending either).	2561	do this when the watcher is inactive (and not pending either).
2500		2562
2501	=item w->set ([args])	2563	=item w->set ([arguments])
2502		2564
2503	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
2504	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
2505	automatically stopped and restarted when reconfiguring it with this	2567	automatically stopped and restarted when reconfiguring it with this
2506	method.	2568	method.
2507		2569
2508	=item w->start ()	2570	=item w->start ()
…		…
2532	=back	2594	=back
2533		2595
2534	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
2535	the constructor.	2597	the constructor.
2536		2598
2537	class myclass	2599	class myclass
2538	{	2600	{
2539	ev::io io; void io_cb (ev::io &w, int revents);	2601	ev::io io; void io_cb (ev::io &w, int revents);
2540	ev:idle idle void idle_cb (ev::idle &w, int revents);	2602	ev:idle idle void idle_cb (ev::idle &w, int revents);
2541		2603
2542	myclass (int fd)	2604	myclass (int fd)
2543	{	2605	{
2544	io .set <myclass, &myclass::io_cb > (this);	2606	io .set <myclass, &myclass::io_cb > (this);
2545	idle.set <myclass, &myclass::idle_cb> (this);	2607	idle.set <myclass, &myclass::idle_cb> (this);
2546		2608
2547	io.start (fd, ev::READ);	2609	io.start (fd, ev::READ);
2548	}	2610	}
2549	};	2611	};
2550		2612
2551		2613
2552	=head1 OTHER LANGUAGE BINDINGS	2614	=head1 OTHER LANGUAGE BINDINGS
2553		2615
2554	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
2555	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
2556	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
2557	me a note.	2619	me a note.
2558		2620
2559	=over 4	2621	=over 4
2560		2622
…		…
2564	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,
2565	there are additional modules that implement libev-compatible interfaces	2627	there are additional modules that implement libev-compatible interfaces
2566	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
2567	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).	2629	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2568		2630
2569	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
2570	L<http://software.schmorp.de/pkg/EV>.	2632	L<http://software.schmorp.de/pkg/EV>.
2571		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
2572	=item Ruby	2643	=item Ruby
2573		2644
2574	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
2575	of the libev API and adds filehandle abstractions, asynchronous DNS and	2646	of the libev API and adds file handle abstractions, asynchronous DNS and
2576	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
2577	L<http://rev.rubyforge.org/>.	2648	L<http://rev.rubyforge.org/>.
2578		2649
2579	=item D	2650	=item D
2580		2651
…		…
2584	=back	2655	=back
2585		2656
2586		2657
2587	=head1 MACRO MAGIC	2658	=head1 MACRO MAGIC
2588		2659
2589	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
2590	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2661	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2591	functions and callbacks have an initial C<struct ev_loop *> argument.	2662	functions and callbacks have an initial C<struct ev_loop *> argument.
2592		2663
2593	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
2594	following macros are defined:	2665	following macros are defined:
…		…
2599		2670
2600	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
2601	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,
2602	C<EV_A_> is used when other arguments are following. Example:	2673	C<EV_A_> is used when other arguments are following. Example:
2603		2674
2604	ev_unref (EV_A);	2675	ev_unref (EV_A);
2605	ev_timer_add (EV_A_ watcher);	2676	ev_timer_add (EV_A_ watcher);
2606	ev_loop (EV_A_ 0);	2677	ev_loop (EV_A_ 0);
2607		2678
2608	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,
2609	which is often provided by the following macro.	2680	which is often provided by the following macro.
2610		2681
2611	=item C<EV_P>, C<EV_P_>	2682	=item C<EV_P>, C<EV_P_>
2612		2683
2613	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
2614	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,
2615	C<EV_P_> is used when other parameters are following. Example:	2686	C<EV_P_> is used when other parameters are following. Example:
2616		2687
2617	// this is how ev_unref is being declared	2688	// this is how ev_unref is being declared
2618	static void ev_unref (EV_P);	2689	static void ev_unref (EV_P);
2619		2690
2620	// this is how you can declare your typical callback	2691	// this is how you can declare your typical callback
2621	static void cb (EV_P_ ev_timer *w, int revents)	2692	static void cb (EV_P_ ev_timer *w, int revents)
2622		2693
2623	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
2624	suitable for use with C<EV_A>.	2695	suitable for use with C<EV_A>.
2625		2696
2626	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2697	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
…		…
2642		2713
2643	Example: Declare and initialise a check watcher, utilising the above	2714	Example: Declare and initialise a check watcher, utilising the above
2644	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
2645	or not.	2716	or not.
2646		2717
2647	static void	2718	static void
2648	check_cb (EV_P_ ev_timer *w, int revents)	2719	check_cb (EV_P_ ev_timer *w, int revents)
2649	{	2720	{
2650	ev_check_stop (EV_A_ w);	2721	ev_check_stop (EV_A_ w);
2651	}	2722	}
2652		2723
2653	ev_check check;	2724	ev_check check;
2654	ev_check_init (&check, check_cb);	2725	ev_check_init (&check, check_cb);
2655	ev_check_start (EV_DEFAULT_ &check);	2726	ev_check_start (EV_DEFAULT_ &check);
2656	ev_loop (EV_DEFAULT_ 0);	2727	ev_loop (EV_DEFAULT_ 0);
2657		2728
2658	=head1 EMBEDDING	2729	=head1 EMBEDDING
2659		2730
2660	Libev can (and often is) directly embedded into host	2731	Libev can (and often is) directly embedded into host
2661	applications. Examples of applications that embed it include the Deliantra	2732	applications. Examples of applications that embed it include the Deliantra
…		…
2668	libev somewhere in your source tree).	2739	libev somewhere in your source tree).
2669		2740
2670	=head2 FILESETS	2741	=head2 FILESETS
2671		2742
2672	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
2673	in your app.	2744	in your application.
2674		2745
2675	=head3 CORE EVENT LOOP	2746	=head3 CORE EVENT LOOP
2676		2747
2677	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
2678	configuration (no autoconf):	2749	configuration (no autoconf):
2679		2750
2680	#define EV_STANDALONE 1	2751	#define EV_STANDALONE 1
2681	#include "ev.c"	2752	#include "ev.c"
2682		2753
2683	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
2684	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
2685	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
2686	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
2687	where you can put other configuration options):	2758	where you can put other configuration options):
2688		2759
2689	#define EV_STANDALONE 1	2760	#define EV_STANDALONE 1
2690	#include "ev.h"	2761	#include "ev.h"
2691		2762
2692	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++
2693	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
2694	as a bug).	2765	as a bug).
2695		2766
2696	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
2697	in your include path (e.g. in libev/ when using -Ilibev):	2768	in your include path (e.g. in libev/ when using -Ilibev):
2698		2769
2699	ev.h	2770	ev.h
2700	ev.c	2771	ev.c
2701	ev_vars.h	2772	ev_vars.h
2702	ev_wrap.h	2773	ev_wrap.h
2703		2774
2704	ev_win32.c required on win32 platforms only	2775	ev_win32.c required on win32 platforms only
2705		2776
2706	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)
2707	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)
2708	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)
2709	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)
2710	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)
2711		2782
2712	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
2713	to compile this single file.	2784	to compile this single file.
2714		2785
2715	=head3 LIBEVENT COMPATIBILITY API	2786	=head3 LIBEVENT COMPATIBILITY API
2716		2787
2717	To include the libevent compatibility API, also include:	2788	To include the libevent compatibility API, also include:
2718		2789
2719	#include "event.c"	2790	#include "event.c"
2720		2791
2721	in the file including F<ev.c>, and:	2792	in the file including F<ev.c>, and:
2722		2793
2723	#include "event.h"	2794	#include "event.h"
2724		2795
2725	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>.
2726		2797
2727	You need the following additional files for this:	2798	You need the following additional files for this:
2728		2799
2729	event.h	2800	event.h
2730	event.c	2801	event.c
2731		2802
2732	=head3 AUTOCONF SUPPORT	2803	=head3 AUTOCONF SUPPORT
2733		2804
2734	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
2735	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
2736	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
2737	include F<config.h> and configure itself accordingly.	2808	include F<config.h> and configure itself accordingly.
2738		2809
2739	For this of course you need the m4 file:	2810	For this of course you need the m4 file:
2740		2811
2741	libev.m4	2812	libev.m4
2742		2813
2743	=head2 PREPROCESSOR SYMBOLS/MACROS	2814	=head2 PREPROCESSOR SYMBOLS/MACROS
2744		2815
2745	Libev can be configured via a variety of preprocessor symbols you have to	2816	Libev can be configured via a variety of preprocessor symbols you have to
2746	define before including any of its files. The default in the absense of	2817	define before including any of its files. The default in the absence of
2747	autoconf is noted for every option.	2818	autoconf is noted for every option.
2748		2819
2749	=over 4	2820	=over 4
2750		2821
2751	=item EV_STANDALONE	2822	=item EV_STANDALONE
…		…
2757	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.
2758		2829
2759	=item EV_USE_MONOTONIC	2830	=item EV_USE_MONOTONIC
2760		2831
2761	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
2762	monotonic clock option at both compiletime and runtime. Otherwise no use	2833	monotonic clock option at both compile time and runtime. Otherwise no use
2763	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
2764	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
2765	the functionality isn't available is safe, though, although you have	2836	the functionality isn't available is safe, though, although you have
2766	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>
2767	function is hiding in (often F<-lrt>).	2838	function is hiding in (often F<-lrt>).
2768		2839
2769	=item EV_USE_REALTIME	2840	=item EV_USE_REALTIME
2770		2841
2771	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
2772	realtime clock option at compiletime (and assume its availability at	2843	real-time clock option at compile time (and assume its availability at
2773	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
2774	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2845	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2775	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2846	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2776	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.
2777		2848
2778	=item EV_USE_NANOSLEEP	2849	=item EV_USE_NANOSLEEP
…		…
2789	2.7 or newer, otherwise disabled.	2860	2.7 or newer, otherwise disabled.
2790		2861
2791	=item EV_USE_SELECT	2862	=item EV_USE_SELECT
2792		2863
2793	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
2794	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
2795	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
2796	will not be compiled in.	2867	will not be compiled in.
2797		2868
2798	=item EV_SELECT_USE_FD_SET	2869	=item EV_SELECT_USE_FD_SET
2799		2870
2800	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>
2801	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
2802	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
2803	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
2804	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
2805	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
2806	influence the size of the C<fd_set> used.	2877	influence the size of the C<fd_set> used.
2807		2878
…		…
2856	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
2857	backend for Solaris 10 systems.	2928	backend for Solaris 10 systems.
2858		2929
2859	=item EV_USE_DEVPOLL	2930	=item EV_USE_DEVPOLL
2860		2931
2861	reserved for future expansion, works like the USE symbols above.	2932	Reserved for future expansion, works like the USE symbols above.
2862		2933
2863	=item EV_USE_INOTIFY	2934	=item EV_USE_INOTIFY
2864		2935
2865	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
2866	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
…		…
2873	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
2874	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
2875	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"
2876	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.
2877		2948
2878	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>
2879	(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.
2880		2951
2881	=item EV_H	2952	=item EV_H
2882		2953
2883	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
…		…
2922	When doing priority-based operations, libev usually has to linearly search	2993	When doing priority-based operations, libev usually has to linearly search
2923	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
2924	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
2925	fine.	2996	fine.
2926		2997
2927	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
2928	C<0> will save some memory and cpu.	2999	C<0> will save some memory and CPU.
2929		3000
2930	=item EV_PERIODIC_ENABLE	3001	=item EV_PERIODIC_ENABLE
2931		3002
2932	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
2933	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
…		…
2960	defined to be C<0>, then they are not.	3031	defined to be C<0>, then they are not.
2961		3032
2962	=item EV_MINIMAL	3033	=item EV_MINIMAL
2963		3034
2964	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
2965	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
2966	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.
2967		3039
2968	=item EV_PID_HASHSIZE	3040	=item EV_PID_HASHSIZE
2969		3041
2970	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
2971	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
…		…
2978	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>),
2979	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>
2980	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
2981	two).	3053	two).
2982		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
2983	=item EV_COMMON	3090	=item EV_COMMON
2984		3091
2985	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
2986	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
2987	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,
2988	though, and it must be identical each time.	3095	though, and it must be identical each time.
2989		3096
2990	For example, the perl EV module uses something like this:	3097	For example, the perl EV module uses something like this:
2991		3098
2992	#define EV_COMMON \	3099	#define EV_COMMON \
2993	SV *self; /* contains this struct */ \	3100	SV *self; /* contains this struct */ \
2994	SV *cb_sv, *fh /* note no trailing ";" */	3101	SV *cb_sv, *fh /* note no trailing ";" */
2995		3102
2996	=item EV_CB_DECLARE (type)	3103	=item EV_CB_DECLARE (type)
2997		3104
2998	=item EV_CB_INVOKE (watcher, revents)	3105	=item EV_CB_INVOKE (watcher, revents)
2999		3106
…		…
3006	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
3007	method calls instead of plain function calls in C++.	3114	method calls instead of plain function calls in C++.
3008		3115
3009	=head2 EXPORTED API SYMBOLS	3116	=head2 EXPORTED API SYMBOLS
3010		3117
3011	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
3012	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
3013	all public symbols, one per line:	3120	all public symbols, one per line:
3014		3121
3015	Symbols.ev for libev proper	3122	Symbols.ev for libev proper
3016	Symbols.event for the libevent emulation	3123	Symbols.event for the libevent emulation
3017		3124
3018	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
3019	multiple versions of libev linked together (which is obviously bad in	3126	multiple versions of libev linked together (which is obviously bad in
3020	itself, but sometimes it is inconvinient to avoid this).	3127	itself, but sometimes it is inconvenient to avoid this).
3021		3128
3022	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
3023	include before including F<ev.h>:	3130	include before including F<ev.h>:
3024		3131
3025	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3132	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3042	file.	3149	file.
3043		3150
3044	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
3045	that everybody includes and which overrides some configure choices:	3152	that everybody includes and which overrides some configure choices:
3046		3153
3047	#define EV_MINIMAL 1	3154	#define EV_MINIMAL 1
3048	#define EV_USE_POLL 0	3155	#define EV_USE_POLL 0
3049	#define EV_MULTIPLICITY 0	3156	#define EV_MULTIPLICITY 0
3050	#define EV_PERIODIC_ENABLE 0	3157	#define EV_PERIODIC_ENABLE 0
3051	#define EV_STAT_ENABLE 0	3158	#define EV_STAT_ENABLE 0
3052	#define EV_FORK_ENABLE 0	3159	#define EV_FORK_ENABLE 0
3053	#define EV_CONFIG_H <config.h>	3160	#define EV_CONFIG_H <config.h>
3054	#define EV_MINPRI 0	3161	#define EV_MINPRI 0
3055	#define EV_MAXPRI 0	3162	#define EV_MAXPRI 0
3056		3163
3057	#include "ev++.h"	3164	#include "ev++.h"
3058		3165
3059	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:
3060		3167
3061	#include "ev_cpp.h"	3168	#include "ev_cpp.h"
3062	#include "ev.c"	3169	#include "ev.c"
3063		3170
3064		3171
3065	=head1 THREADS AND COROUTINES	3172	=head1 THREADS AND COROUTINES
3066		3173
3067	=head2 THREADS	3174	=head2 THREADS
3068		3175
3069	Libev itself is completely threadsafe, but it uses no locking. This	3176	Libev itself is completely thread-safe, but it uses no locking. This
3070	means that you can use as many loops as you want in parallel, as long as	3177	means that you can use as many loops as you want in parallel, as long as
3071	only one thread ever calls into one libev function with the same loop	3178	only one thread ever calls into one libev function with the same loop
3072	parameter.	3179	parameter.
3073		3180
3074	Or put differently: calls with different loop parameters can be done in	3181	Or put differently: calls with different loop parameters can be done in
…		…
3081	help you but by giving some generic advice:	3188	help you but by giving some generic advice:
3082		3189
3083	=over 4	3190	=over 4
3084		3191
3085	=item * most applications have a main thread: use the default libev loop	3192	=item * most applications have a main thread: use the default libev loop
3086	in that thread, or create a seperate thread running only the default loop.	3193	in that thread, or create a separate thread running only the default loop.
3087		3194
3088	This helps integrating other libraries or software modules that use libev	3195	This helps integrating other libraries or software modules that use libev
3089	themselves and don't care/know about threading.	3196	themselves and don't care/know about threading.
3090		3197
3091	=item * one loop per thread is usually a good model.	3198	=item * one loop per thread is usually a good model.
3092		3199
3093	Doing this is almost never wrong, sometimes a better-performance model	3200	Doing this is almost never wrong, sometimes a better-performance model
3094	exists, but it is always a good start.	3201	exists, but it is always a good start.
3095		3202
3096	=item * other models exist, such as the leader/follower pattern, where one	3203	=item * other models exist, such as the leader/follower pattern, where one
3097	loop is handed through multiple threads in a kind of round-robbin fashion.	3204	loop is handed through multiple threads in a kind of round-robin fashion.
3098		3205
3099	Chosing a model is hard - look around, learn, know that usually you cna do	3206	Choosing a model is hard - look around, learn, know that usually you can do
3100	better than you currently do :-)	3207	better than you currently do :-)
3101		3208
3102	=item * often you need to talk to some other thread which blocks in the	3209	=item * often you need to talk to some other thread which blocks in the
3103	event loop - C<ev_async> watchers can be used to wake them up from other	3210	event loop - C<ev_async> watchers can be used to wake them up from other
3104	threads safely (or from signal contexts...).	3211	threads safely (or from signal contexts...).
3105		3212
3106	=back	3213	=back
3107		3214
3108	=head2 COROUTINES	3215	=head2 COROUTINES
3109		3216
3110	Libev is much more accomodating to coroutines ("cooperative threads"):	3217	Libev is much more accommodating to coroutines ("cooperative threads"):
3111	libev fully supports nesting calls to it's functions from different	3218	libev fully supports nesting calls to it's functions from different
3112	coroutines (e.g. you can call C<ev_loop> on the same loop from two	3219	coroutines (e.g. you can call C<ev_loop> on the same loop from two
3113	different coroutines and switch freely between both coroutines running the	3220	different coroutines and switch freely between both coroutines running the
3114	loop, as long as you don't confuse yourself). The only exception is that	3221	loop, as long as you don't confuse yourself). The only exception is that
3115	you must not do this from C<ev_periodic> reschedule callbacks.	3222	you must not do this from C<ev_periodic> reschedule callbacks.
…		…
3156	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
3157	have many watchers waiting for the same fd or signal).	3264	have many watchers waiting for the same fd or signal).
3158		3265
3159	=item Finding the next timer in each loop iteration: O(1)	3266	=item Finding the next timer in each loop iteration: O(1)
3160		3267
3161	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
3162	beginning of the storage array.	3269	fixed position in the storage array.
3163		3270
3164	=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)
3165		3272
3166	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
3167	libev to recalculate its status (and possibly tell the kernel, depending	3274	libev to recalculate its status (and possibly tell the kernel, depending
3168	on backend and wether C<ev_io_set> was used).	3275	on backend and whether C<ev_io_set> was used).
3169		3276
3170	=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)
3171		3278
3172	=item Priority handling: O(number_of_priorities)	3279	=item Priority handling: O(number_of_priorities)
3173		3280
…		…
3180		3287
3181	=item Processing ev_async_send: O(number_of_async_watchers)	3288	=item Processing ev_async_send: O(number_of_async_watchers)
3182		3289
3183	=item Processing signals: O(max_signal_number)	3290	=item Processing signals: O(max_signal_number)
3184		3291
3185	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>
3186	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
3187	involves iterating over all running async watchers or all signal numbers.	3294	involves iterating over all running async watchers or all signal numbers.
3188		3295
3189	=back	3296	=back
3190		3297
3191		3298
3192	=head1 Win32 platform limitations and workarounds	3299	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3193		3300
3194	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
3195	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
3196	model. Libev still offers limited functionality on this platform in	3303	model. Libev still offers limited functionality on this platform in
3197	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
3198	descriptors. This only applies when using Win32 natively, not when using	3305	descriptors. This only applies when using Win32 natively, not when using
3199	e.g. cygwin.	3306	e.g. cygwin.
3200		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
3201	There is no supported compilation method available on windows except	3313	There is no supported compilation method available on windows except
3202	embedding it into other applications.	3314	embedding it into other applications.
3203		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
3204	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
3205	abysmal performance of winsockets, using a large number of sockets is not	3324	the abysmal performance of winsockets, using a large number of sockets
3206	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
3207	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
3208	implementation for windows, as libev offers the POSIX model, which cannot	3327	different implementation for windows, as libev offers the POSIX readiness
3209	be implemented efficiently on windows (microsoft monopoly games).	3328	notification model, which cannot be implemented efficiently on windows
		3329	(Microsoft monopoly games).
3210		3330
3211	=over 4	3331	=over 4
3212		3332
3213	=item The winsocket select function	3333	=item The winsocket select function
3214		3334
3215	The winsocket C<select> function doesn't follow POSIX in that it requires	3335	The winsocket C<select> function doesn't follow POSIX in that it
3216	socket I<handles> and not socket I<file descriptors>. This makes select	3336	requires socket I<handles> and not socket I<file descriptors> (it is
3217	very inefficient, and also requires a mapping from file descriptors	3337	also extremely buggy). This makes select very inefficient, and also
3218	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,	3338	requires a mapping from file descriptors to socket handles. See the
3219	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor	3339	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
3220	symbols for more info.	3340	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3221		3341
3222	The configuration for a "naked" win32 using the microsoft runtime	3342	The configuration for a "naked" win32 using the Microsoft runtime
3223	libraries and raw winsocket select is:	3343	libraries and raw winsocket select is:
3224		3344
3225	#define EV_USE_SELECT 1	3345	#define EV_USE_SELECT 1
3226	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3346	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3227		3347
3228	Note that winsockets handling of fd sets is O(n), so you can easily get a	3348	Note that winsockets handling of fd sets is O(n), so you can easily get a
3229	complexity in the O(n²) range when using win32.	3349	complexity in the O(n²) range when using win32.
3230		3350
3231	=item Limited number of file descriptors	3351	=item Limited number of file descriptors
3232		3352
3233	Windows has numerous arbitrary (and low) limits on things. Early versions	3353	Windows has numerous arbitrary (and low) limits on things.
3234	of winsocket's select only supported waiting for a max. of C<64> handles	3354
		3355	Early versions of winsocket's select only supported waiting for a maximum
3235	(probably owning to the fact that all windows kernels can only wait for	3356	of C<64> handles (probably owning to the fact that all windows kernels
3236	C<64> things at the same time internally; microsoft recommends spawning a	3357	can only wait for C<64> things at the same time internally; Microsoft
3237	chain of threads and wait for 63 handles and the previous thread in each).	3358	recommends spawning a chain of threads and wait for 63 handles and the
		3359	previous thread in each. Great).
3238		3360
3239	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3361	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3240	to some high number (e.g. C<2048>) before compiling the winsocket select	3362	to some high number (e.g. C<2048>) before compiling the winsocket select
3241	call (which might be in libev or elsewhere, for example, perl does its own	3363	call (which might be in libev or elsewhere, for example, perl does its own
3242	select emulation on windows).	3364	select emulation on windows).
3243		3365
3244	Another limit is the number of file descriptors in the microsoft runtime	3366	Another limit is the number of file descriptors in the Microsoft runtime
3245	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3367	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3246	or something like this inside microsoft). You can increase this by calling	3368	or something like this inside Microsoft). You can increase this by calling
3247	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3369	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3248	arbitrary limit), but is broken in many versions of the microsoft runtime	3370	arbitrary limit), but is broken in many versions of the Microsoft runtime
3249	libraries.	3371	libraries.
3250		3372
3251	This might get you to about C<512> or C<2048> sockets (depending on	3373	This might get you to about C<512> or C<2048> sockets (depending on
3252	windows version and/or the phase of the moon). To get more, you need to	3374	windows version and/or the phase of the moon). To get more, you need to
3253	wrap all I/O functions and provide your own fd management, but the cost of	3375	wrap all I/O functions and provide your own fd management, but the cost of
3254	calling select (O(n²)) will likely make this unworkable.	3376	calling select (O(n²)) will likely make this unworkable.
3255		3377
3256	=back	3378	=back
3257		3379
3258		3380
		3381	=head1 PORTABILITY REQUIREMENTS
		3382
		3383	In addition to a working ISO-C implementation, libev relies on a few
		3384	additional extensions:
		3385
		3386	=over 4
		3387
		3388	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3389	calling conventions regardless of C<ev_watcher_type *>.
		3390
		3391	Libev assumes not only that all watcher pointers have the same internal
		3392	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3393	assumes that the same (machine) code can be used to call any watcher
		3394	callback: The watcher callbacks have different type signatures, but libev
		3395	calls them using an C<ev_watcher *> internally.
		3396
		3397	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3398
		3399	The type C<sig_atomic_t volatile> (or whatever is defined as
		3400	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3401	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3402	believed to be sufficiently portable.
		3403
		3404	=item C<sigprocmask> must work in a threaded environment
		3405
		3406	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3407	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3408	pthread implementations will either allow C<sigprocmask> in the "main
		3409	thread" or will block signals process-wide, both behaviours would
		3410	be compatible with libev. Interaction between C<sigprocmask> and
		3411	C<pthread_sigmask> could complicate things, however.
		3412
		3413	The most portable way to handle signals is to block signals in all threads
		3414	except the initial one, and run the default loop in the initial thread as
		3415	well.
		3416
		3417	=item C<long> must be large enough for common memory allocation sizes
		3418
		3419	To improve portability and simplify using libev, libev uses C<long>
		3420	internally instead of C<size_t> when allocating its data structures. On
		3421	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3422	is still at least 31 bits everywhere, which is enough for hundreds of
		3423	millions of watchers.
		3424
		3425	=item C<double> must hold a time value in seconds with enough accuracy
		3426
		3427	The type C<double> is used to represent timestamps. It is required to
		3428	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3429	enough for at least into the year 4000. This requirement is fulfilled by
		3430	implementations implementing IEEE 754 (basically all existing ones).
		3431
		3432	=back
		3433
		3434	If you know of other additional requirements drop me a note.
		3435
		3436
		3437	=head1 COMPILER WARNINGS
		3438
		3439	Depending on your compiler and compiler settings, you might get no or a
		3440	lot of warnings when compiling libev code. Some people are apparently
		3441	scared by this.
		3442
		3443	However, these are unavoidable for many reasons. For one, each compiler
		3444	has different warnings, and each user has different tastes regarding
		3445	warning options. "Warn-free" code therefore cannot be a goal except when
		3446	targeting a specific compiler and compiler-version.
		3447
		3448	Another reason is that some compiler warnings require elaborate
		3449	workarounds, or other changes to the code that make it less clear and less
		3450	maintainable.
		3451
		3452	And of course, some compiler warnings are just plain stupid, or simply
		3453	wrong (because they don't actually warn about the condition their message
		3454	seems to warn about).
		3455
		3456	While libev is written to generate as few warnings as possible,
		3457	"warn-free" code is not a goal, and it is recommended not to build libev
		3458	with any compiler warnings enabled unless you are prepared to cope with
		3459	them (e.g. by ignoring them). Remember that warnings are just that:
		3460	warnings, not errors, or proof of bugs.
		3461
		3462
		3463	=head1 VALGRIND
		3464
		3465	Valgrind has a special section here because it is a popular tool that is
		3466	highly useful, but valgrind reports are very hard to interpret.
		3467
		3468	If you think you found a bug (memory leak, uninitialised data access etc.)
		3469	in libev, then check twice: If valgrind reports something like:
		3470
		3471	==2274== definitely lost: 0 bytes in 0 blocks.
		3472	==2274== possibly lost: 0 bytes in 0 blocks.
		3473	==2274== still reachable: 256 bytes in 1 blocks.
		3474
		3475	Then there is no memory leak. Similarly, under some circumstances,
		3476	valgrind might report kernel bugs as if it were a bug in libev, or it
		3477	might be confused (it is a very good tool, but only a tool).
		3478
		3479	If you are unsure about something, feel free to contact the mailing list
		3480	with the full valgrind report and an explanation on why you think this is
		3481	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3482	no bug" answer and take the chance of learning how to interpret valgrind
		3483	properly.
		3484
		3485	If you need, for some reason, empty reports from valgrind for your project
		3486	I suggest using suppression lists.
		3487
		3488
3259	=head1 AUTHOR	3489	=head1 AUTHOR
3260		3490
3261	Marc Lehmann <libev@schmorp.de>.	3491	Marc Lehmann <libev@schmorp.de>.
3262		3492

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