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Revision 1.139 by root, Wed Apr 2 05:51:40 2008 UTC vs.
Revision 1.179 by root, Sat Sep 13 19:14:21 2008 UTC

…		…
2		2
3	libev - a high performance full-featured event loop written in C	3	libev - a high performance full-featured event loop written in C
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
9	=head2 EXAMPLE PROGRAM	9	=head2 EXAMPLE PROGRAM
10		10
11	// a single header file is required	11	// a single header file is required
12	#include <ev.h>	12	#include <ev.h>
13		13
14	// every watcher type has its own typedef'd struct	14	// every watcher type has its own typedef'd struct
15	// with the name ev_<type>	15	// with the name ev_<type>
16	ev_io stdin_watcher;	16	ev_io stdin_watcher;
17	ev_timer timeout_watcher;	17	ev_timer timeout_watcher;
18		18
19	// all watcher callbacks have a similar signature	19	// all watcher callbacks have a similar signature
20	// this callback is called when data is readable on stdin	20	// this callback is called when data is readable on stdin
21	static void	21	static void
22	stdin_cb (EV_P_ struct ev_io *w, int revents)	22	stdin_cb (EV_P_ struct ev_io *w, int revents)
23	{	23	{
24	puts ("stdin ready");	24	puts ("stdin ready");
25	// for one-shot events, one must manually stop the watcher	25	// for one-shot events, one must manually stop the watcher
26	// with its corresponding stop function.	26	// with its corresponding stop function.
27	ev_io_stop (EV_A_ w);	27	ev_io_stop (EV_A_ w);
28		28
29	// this causes all nested ev_loop's to stop iterating	29	// this causes all nested ev_loop's to stop iterating
30	ev_unloop (EV_A_ EVUNLOOP_ALL);	30	ev_unloop (EV_A_ EVUNLOOP_ALL);
31	}	31	}
32		32
33	// another callback, this time for a time-out	33	// another callback, this time for a time-out
34	static void	34	static void
35	timeout_cb (EV_P_ struct ev_timer *w, int revents)	35	timeout_cb (EV_P_ struct ev_timer *w, int revents)
36	{	36	{
37	puts ("timeout");	37	puts ("timeout");
38	// this causes the innermost ev_loop to stop iterating	38	// this causes the innermost ev_loop to stop iterating
39	ev_unloop (EV_A_ EVUNLOOP_ONE);	39	ev_unloop (EV_A_ EVUNLOOP_ONE);
40	}	40	}
41		41
42	int	42	int
43	main (void)	43	main (void)
44	{	44	{
45	// use the default event loop unless you have special needs	45	// use the default event loop unless you have special needs
46	struct ev_loop *loop = ev_default_loop (0);	46	struct ev_loop *loop = ev_default_loop (0);
47		47
48	// initialise an io watcher, then start it	48	// initialise an io watcher, then start it
49	// this one will watch for stdin to become readable	49	// this one will watch for stdin to become readable
50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
51	ev_io_start (loop, &stdin_watcher);	51	ev_io_start (loop, &stdin_watcher);
52		52
53	// initialise a timer watcher, then start it	53	// initialise a timer watcher, then start it
54	// simple non-repeating 5.5 second timeout	54	// simple non-repeating 5.5 second timeout
55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
56	ev_timer_start (loop, &timeout_watcher);	56	ev_timer_start (loop, &timeout_watcher);
57		57
58	// now wait for events to arrive	58	// now wait for events to arrive
59	ev_loop (loop, 0);	59	ev_loop (loop, 0);
60		60
61	// unloop was called, so exit	61	// unloop was called, so exit
62	return 0;	62	return 0;
63	}	63	}
64		64
65	=head1 DESCRIPTION	65	=head1 DESCRIPTION
66		66
67	The newest version of this document is also available as an html-formatted	67	The newest version of this document is also available as an html-formatted
68	web page you might find easier to navigate when reading it for the first	68	web page you might find easier to navigate when reading it for the first
69	time: L<http://cvs.schmorp.de/libev/ev.html>.	69	time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>.
70		70
71	Libev is an event loop: you register interest in certain events (such as a	71	Libev is an event loop: you register interest in certain events (such as a
72	file descriptor being readable or a timeout occurring), and it will manage	72	file descriptor being readable or a timeout occurring), and it will manage
73	these event sources and provide your program with events.	73	these event sources and provide your program with events.
74		74
…		…
113	Libev represents time as a single floating point number, representing the	113	Libev represents time as a single floating point number, representing the
114	(fractional) number of seconds since the (POSIX) epoch (somewhere near	114	(fractional) number of seconds since the (POSIX) epoch (somewhere near
115	the beginning of 1970, details are complicated, don't ask). This type is	115	the beginning of 1970, details are complicated, don't ask). This type is
116	called C<ev_tstamp>, which is what you should use too. It usually aliases	116	called C<ev_tstamp>, which is what you should use too. It usually aliases
117	to the C<double> type in C, and when you need to do any calculations on	117	to the C<double> type in C, and when you need to do any calculations on
118	it, you should treat it as some floatingpoint value. Unlike the name	118	it, you should treat it as some floating point value. Unlike the name
119	component C<stamp> might indicate, it is also used for time differences	119	component C<stamp> might indicate, it is also used for time differences
120	throughout libev.	120	throughout libev.
		121
		122	=head1 ERROR HANDLING
		123
		124	Libev knows three classes of errors: operating system errors, usage errors
		125	and internal errors (bugs).
		126
		127	When libev catches an operating system error it cannot handle (for example
		128	a system call indicating a condition libev cannot fix), it calls the callback
		129	set via C<ev_set_syserr_cb>, which is supposed to fix the problem or
		130	abort. The default is to print a diagnostic message and to call C<abort
		131	()>.
		132
		133	When libev detects a usage error such as a negative timer interval, then
		134	it will print a diagnostic message and abort (via the C<assert> mechanism,
		135	so C<NDEBUG> will disable this checking): these are programming errors in
		136	the libev caller and need to be fixed there.
		137
		138	Libev also has a few internal error-checking C<assert>ions, and also has
		139	extensive consistency checking code. These do not trigger under normal
		140	circumstances, as they indicate either a bug in libev or worse.
		141
121		142
122	=head1 GLOBAL FUNCTIONS	143	=head1 GLOBAL FUNCTIONS
123		144
124	These functions can be called anytime, even before initialising the	145	These functions can be called anytime, even before initialising the
125	library in any way.	146	library in any way.
…		…
134		155
135	=item ev_sleep (ev_tstamp interval)	156	=item ev_sleep (ev_tstamp interval)
136		157
137	Sleep for the given interval: The current thread will be blocked until	158	Sleep for the given interval: The current thread will be blocked until
138	either it is interrupted or the given time interval has passed. Basically	159	either it is interrupted or the given time interval has passed. Basically
139	this is a subsecond-resolution C<sleep ()>.	160	this is a sub-second-resolution C<sleep ()>.
140		161
141	=item int ev_version_major ()	162	=item int ev_version_major ()
142		163
143	=item int ev_version_minor ()	164	=item int ev_version_minor ()
144		165
…		…
157	not a problem.	178	not a problem.
158		179
159	Example: Make sure we haven't accidentally been linked against the wrong	180	Example: Make sure we haven't accidentally been linked against the wrong
160	version.	181	version.
161		182
162	assert (("libev version mismatch",	183	assert (("libev version mismatch",
163	ev_version_major () == EV_VERSION_MAJOR	184	ev_version_major () == EV_VERSION_MAJOR
164	&& ev_version_minor () >= EV_VERSION_MINOR));	185	&& ev_version_minor () >= EV_VERSION_MINOR));
165		186
166	=item unsigned int ev_supported_backends ()	187	=item unsigned int ev_supported_backends ()
167		188
168	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>	189	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>
169	value) compiled into this binary of libev (independent of their	190	value) compiled into this binary of libev (independent of their
…		…
171	a description of the set values.	192	a description of the set values.
172		193
173	Example: make sure we have the epoll method, because yeah this is cool and	194	Example: make sure we have the epoll method, because yeah this is cool and
174	a must have and can we have a torrent of it please!!!11	195	a must have and can we have a torrent of it please!!!11
175		196
176	assert (("sorry, no epoll, no sex",	197	assert (("sorry, no epoll, no sex",
177	ev_supported_backends () & EVBACKEND_EPOLL));	198	ev_supported_backends () & EVBACKEND_EPOLL));
178		199
179	=item unsigned int ev_recommended_backends ()	200	=item unsigned int ev_recommended_backends ()
180		201
181	Return the set of all backends compiled into this binary of libev and also	202	Return the set of all backends compiled into this binary of libev and also
182	recommended for this platform. This set is often smaller than the one	203	recommended for this platform. This set is often smaller than the one
183	returned by C<ev_supported_backends>, as for example kqueue is broken on	204	returned by C<ev_supported_backends>, as for example kqueue is broken on
184	most BSDs and will not be autodetected unless you explicitly request it	205	most BSDs and will not be auto-detected unless you explicitly request it
185	(assuming you know what you are doing). This is the set of backends that	206	(assuming you know what you are doing). This is the set of backends that
186	libev will probe for if you specify no backends explicitly.	207	libev will probe for if you specify no backends explicitly.
187		208
188	=item unsigned int ev_embeddable_backends ()	209	=item unsigned int ev_embeddable_backends ()
189		210
…		…
196	See the description of C<ev_embed> watchers for more info.	217	See the description of C<ev_embed> watchers for more info.
197		218
198	=item ev_set_allocator (void *(*cb)(void *ptr, long size))	219	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
199		220
200	Sets the allocation function to use (the prototype is similar - the	221	Sets the allocation function to use (the prototype is similar - the
201	semantics is identical - to the realloc C function). It is used to	222	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
202	allocate and free memory (no surprises here). If it returns zero when	223	used to allocate and free memory (no surprises here). If it returns zero
203	memory needs to be allocated, the library might abort or take some	224	when memory needs to be allocated (C<size != 0>), the library might abort
204	potentially destructive action. The default is your system realloc	225	or take some potentially destructive action.
205	function.	226
		227	Since some systems (at least OpenBSD and Darwin) fail to implement
		228	correct C<realloc> semantics, libev will use a wrapper around the system
		229	C<realloc> and C<free> functions by default.
206		230
207	You could override this function in high-availability programs to, say,	231	You could override this function in high-availability programs to, say,
208	free some memory if it cannot allocate memory, to use a special allocator,	232	free some memory if it cannot allocate memory, to use a special allocator,
209	or even to sleep a while and retry until some memory is available.	233	or even to sleep a while and retry until some memory is available.
210		234
211	Example: Replace the libev allocator with one that waits a bit and then	235	Example: Replace the libev allocator with one that waits a bit and then
212	retries).	236	retries (example requires a standards-compliant C<realloc>).
213		237
214	static void *	238	static void *
215	persistent_realloc (void *ptr, size_t size)	239	persistent_realloc (void *ptr, size_t size)
216	{	240	{
217	for (;;)	241	for (;;)
…		…
228	...	252	...
229	ev_set_allocator (persistent_realloc);	253	ev_set_allocator (persistent_realloc);
230		254
231	=item ev_set_syserr_cb (void (*cb)(const char *msg));	255	=item ev_set_syserr_cb (void (*cb)(const char *msg));
232		256
233	Set the callback function to call on a retryable syscall error (such	257	Set the callback function to call on a retryable system call error (such
234	as failed select, poll, epoll_wait). The message is a printable string	258	as failed select, poll, epoll_wait). The message is a printable string
235	indicating the system call or subsystem causing the problem. If this	259	indicating the system call or subsystem causing the problem. If this
236	callback is set, then libev will expect it to remedy the sitution, no	260	callback is set, then libev will expect it to remedy the situation, no
237	matter what, when it returns. That is, libev will generally retry the	261	matter what, when it returns. That is, libev will generally retry the
238	requested operation, or, if the condition doesn't go away, do bad stuff	262	requested operation, or, if the condition doesn't go away, do bad stuff
239	(such as abort).	263	(such as abort).
240		264
241	Example: This is basically the same thing that libev does internally, too.	265	Example: This is basically the same thing that libev does internally, too.
…		…
255	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	279	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP
256		280
257	An event loop is described by a C<struct ev_loop *>. The library knows two	281	An event loop is described by a C<struct ev_loop *>. The library knows two
258	types of such loops, the I<default> loop, which supports signals and child	282	types of such loops, the I<default> loop, which supports signals and child
259	events, and dynamically created loops which do not.	283	events, and dynamically created loops which do not.
260
261	If you use threads, a common model is to run the default event loop
262	in your main thread (or in a separate thread) and for each thread you
263	create, you also create another event loop. Libev itself does no locking
264	whatsoever, so if you mix calls to the same event loop in different
265	threads, make sure you lock (this is usually a bad idea, though, even if
266	done correctly, because it's hideous and inefficient).
267		284
268	=over 4	285	=over 4
269		286
270	=item struct ev_loop *ev_default_loop (unsigned int flags)	287	=item struct ev_loop *ev_default_loop (unsigned int flags)
271		288
…		…
281	from multiple threads, you have to lock (note also that this is unlikely,	298	from multiple threads, you have to lock (note also that this is unlikely,
282	as loops cannot bes hared easily between threads anyway).	299	as loops cannot bes hared easily between threads anyway).
283		300
284	The default loop is the only loop that can handle C<ev_signal> and	301	The default loop is the only loop that can handle C<ev_signal> and
285	C<ev_child> watchers, and to do this, it always registers a handler	302	C<ev_child> watchers, and to do this, it always registers a handler
286	for C<SIGCHLD>. If this is a problem for your app you can either	303	for C<SIGCHLD>. If this is a problem for your application you can either
287	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	304	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
288	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	305	can simply overwrite the C<SIGCHLD> signal handler I<after> calling
289	C<ev_default_init>.	306	C<ev_default_init>.
290		307
291	The flags argument can be used to specify special behaviour or specific	308	The flags argument can be used to specify special behaviour or specific
…		…
300	The default flags value. Use this if you have no clue (it's the right	317	The default flags value. Use this if you have no clue (it's the right
301	thing, believe me).	318	thing, believe me).
302		319
303	=item C<EVFLAG_NOENV>	320	=item C<EVFLAG_NOENV>
304		321
305	If this flag bit is ored into the flag value (or the program runs setuid	322	If this flag bit is or'ed into the flag value (or the program runs setuid
306	or setgid) then libev will I<not> look at the environment variable	323	or setgid) then libev will I<not> look at the environment variable
307	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	324	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
308	override the flags completely if it is found in the environment. This is	325	override the flags completely if it is found in the environment. This is
309	useful to try out specific backends to test their performance, or to work	326	useful to try out specific backends to test their performance, or to work
310	around bugs.	327	around bugs.
…		…
317		334
318	This works by calling C<getpid ()> on every iteration of the loop,	335	This works by calling C<getpid ()> on every iteration of the loop,
319	and thus this might slow down your event loop if you do a lot of loop	336	and thus this might slow down your event loop if you do a lot of loop
320	iterations and little real work, but is usually not noticeable (on my	337	iterations and little real work, but is usually not noticeable (on my
321	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	338	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
322	without a syscall and thus I<very> fast, but my GNU/Linux system also has	339	without a system call and thus I<very> fast, but my GNU/Linux system also has
323	C<pthread_atfork> which is even faster).	340	C<pthread_atfork> which is even faster).
324		341
325	The big advantage of this flag is that you can forget about fork (and	342	The big advantage of this flag is that you can forget about fork (and
326	forget about forgetting to tell libev about forking) when you use this	343	forget about forgetting to tell libev about forking) when you use this
327	flag.	344	flag.
328		345
329	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>	346	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
330	environment variable.	347	environment variable.
331		348
332	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	349	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
333		350
334	This is your standard select(2) backend. Not I<completely> standard, as	351	This is your standard select(2) backend. Not I<completely> standard, as
…		…
336	but if that fails, expect a fairly low limit on the number of fds when	353	but if that fails, expect a fairly low limit on the number of fds when
337	using this backend. It doesn't scale too well (O(highest_fd)), but its	354	using this backend. It doesn't scale too well (O(highest_fd)), but its
338	usually the fastest backend for a low number of (low-numbered :) fds.	355	usually the fastest backend for a low number of (low-numbered :) fds.
339		356
340	To get good performance out of this backend you need a high amount of	357	To get good performance out of this backend you need a high amount of
341	parallelity (most of the file descriptors should be busy). If you are	358	parallelism (most of the file descriptors should be busy). If you are
342	writing a server, you should C<accept ()> in a loop to accept as many	359	writing a server, you should C<accept ()> in a loop to accept as many
343	connections as possible during one iteration. You might also want to have	360	connections as possible during one iteration. You might also want to have
344	a look at C<ev_set_io_collect_interval ()> to increase the amount of	361	a look at C<ev_set_io_collect_interval ()> to increase the amount of
345	readyness notifications you get per iteration.	362	readiness notifications you get per iteration.
		363
		364	This backend maps C<EV_READ> to the C<readfds> set and C<EV_WRITE> to the
		365	C<writefds> set (and to work around Microsoft Windows bugs, also onto the
		366	C<exceptfds> set on that platform).
346		367
347	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	368	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
348		369
349	And this is your standard poll(2) backend. It's more complicated	370	And this is your standard poll(2) backend. It's more complicated
350	than select, but handles sparse fds better and has no artificial	371	than select, but handles sparse fds better and has no artificial
351	limit on the number of fds you can use (except it will slow down	372	limit on the number of fds you can use (except it will slow down
352	considerably with a lot of inactive fds). It scales similarly to select,	373	considerably with a lot of inactive fds). It scales similarly to select,
353	i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for	374	i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for
354	performance tips.	375	performance tips.
355		376
		377	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and
		378	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.
		379
356	=item C<EVBACKEND_EPOLL> (value 4, Linux)	380	=item C<EVBACKEND_EPOLL> (value 4, Linux)
357		381
358	For few fds, this backend is a bit little slower than poll and select,	382	For few fds, this backend is a bit little slower than poll and select,
359	but it scales phenomenally better. While poll and select usually scale	383	but it scales phenomenally better. While poll and select usually scale
360	like O(total_fds) where n is the total number of fds (or the highest fd),	384	like O(total_fds) where n is the total number of fds (or the highest fd),
361	epoll scales either O(1) or O(active_fds). The epoll design has a number	385	epoll scales either O(1) or O(active_fds). The epoll design has a number
362	of shortcomings, such as silently dropping events in some hard-to-detect	386	of shortcomings, such as silently dropping events in some hard-to-detect
363	cases and rewiring a syscall per fd change, no fork support and bad	387	cases and requiring a system call per fd change, no fork support and bad
364	support for dup.	388	support for dup.
365		389
366	While stopping, setting and starting an I/O watcher in the same iteration	390	While stopping, setting and starting an I/O watcher in the same iteration
367	will result in some caching, there is still a syscall per such incident	391	will result in some caching, there is still a system call per such incident
368	(because the fd could point to a different file description now), so its	392	(because the fd could point to a different file description now), so its
369	best to avoid that. Also, C<dup ()>'ed file descriptors might not work	393	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
370	very well if you register events for both fds.	394	very well if you register events for both fds.
371		395
372	Please note that epoll sometimes generates spurious notifications, so you	396	Please note that epoll sometimes generates spurious notifications, so you
…		…
375		399
376	Best performance from this backend is achieved by not unregistering all	400	Best performance from this backend is achieved by not unregistering all
377	watchers for a file descriptor until it has been closed, if possible, i.e.	401	watchers for a file descriptor until it has been closed, if possible, i.e.
378	keep at least one watcher active per fd at all times.	402	keep at least one watcher active per fd at all times.
379		403
380	While nominally embeddeble in other event loops, this feature is broken in	404	While nominally embeddable in other event loops, this feature is broken in
381	all kernel versions tested so far.	405	all kernel versions tested so far.
		406
		407	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
		408	C<EVBACKEND_POLL>.
382		409
383	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	410	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
384		411
385	Kqueue deserves special mention, as at the time of this writing, it	412	Kqueue deserves special mention, as at the time of this writing, it
386	was broken on all BSDs except NetBSD (usually it doesn't work reliably	413	was broken on all BSDs except NetBSD (usually it doesn't work reliably
387	with anything but sockets and pipes, except on Darwin, where of course	414	with anything but sockets and pipes, except on Darwin, where of course
388	it's completely useless). For this reason it's not being "autodetected"	415	it's completely useless). For this reason it's not being "auto-detected"
389	unless you explicitly specify it explicitly in the flags (i.e. using	416	unless you explicitly specify it explicitly in the flags (i.e. using
390	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)	417	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
391	system like NetBSD.	418	system like NetBSD.
392		419
393	You still can embed kqueue into a normal poll or select backend and use it	420	You still can embed kqueue into a normal poll or select backend and use it
…		…
395	the target platform). See C<ev_embed> watchers for more info.	422	the target platform). See C<ev_embed> watchers for more info.
396		423
397	It scales in the same way as the epoll backend, but the interface to the	424	It scales in the same way as the epoll backend, but the interface to the
398	kernel is more efficient (which says nothing about its actual speed, of	425	kernel is more efficient (which says nothing about its actual speed, of
399	course). While stopping, setting and starting an I/O watcher does never	426	course). While stopping, setting and starting an I/O watcher does never
400	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to	427	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
401	two event changes per incident, support for C<fork ()> is very bad and it	428	two event changes per incident, support for C<fork ()> is very bad and it
402	drops fds silently in similarly hard-to-detect cases.	429	drops fds silently in similarly hard-to-detect cases.
403		430
404	This backend usually performs well under most conditions.	431	This backend usually performs well under most conditions.
405		432
…		…
408	almost everywhere, you should only use it when you have a lot of sockets	435	almost everywhere, you should only use it when you have a lot of sockets
409	(for which it usually works), by embedding it into another event loop	436	(for which it usually works), by embedding it into another event loop
410	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for	437	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for
411	sockets.	438	sockets.
412		439
		440	This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with
		441	C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with
		442	C<NOTE_EOF>.
		443
413	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	444	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
414		445
415	This is not implemented yet (and might never be, unless you send me an	446	This is not implemented yet (and might never be, unless you send me an
416	implementation). According to reports, C</dev/poll> only supports sockets	447	implementation). According to reports, C</dev/poll> only supports sockets
417	and is not embeddable, which would limit the usefulness of this backend	448	and is not embeddable, which would limit the usefulness of this backend
…		…
420	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	451	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
421		452
422	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	453	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
423	it's really slow, but it still scales very well (O(active_fds)).	454	it's really slow, but it still scales very well (O(active_fds)).
424		455
425	Please note that solaris event ports can deliver a lot of spurious	456	Please note that Solaris event ports can deliver a lot of spurious
426	notifications, so you need to use non-blocking I/O or other means to avoid	457	notifications, so you need to use non-blocking I/O or other means to avoid
427	blocking when no data (or space) is available.	458	blocking when no data (or space) is available.
428		459
429	While this backend scales well, it requires one system call per active	460	While this backend scales well, it requires one system call per active
430	file descriptor per loop iteration. For small and medium numbers of file	461	file descriptor per loop iteration. For small and medium numbers of file
431	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	462	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
432	might perform better.	463	might perform better.
433		464
434	On the positive side, ignoring the spurious readyness notifications, this	465	On the positive side, ignoring the spurious readiness notifications, this
435	backend actually performed to specification in all tests and is fully	466	backend actually performed to specification in all tests and is fully
436	embeddable, which is a rare feat among the OS-specific backends.	467	embeddable, which is a rare feat among the OS-specific backends.
		468
		469	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
		470	C<EVBACKEND_POLL>.
437		471
438	=item C<EVBACKEND_ALL>	472	=item C<EVBACKEND_ALL>
439		473
440	Try all backends (even potentially broken ones that wouldn't be tried	474	Try all backends (even potentially broken ones that wouldn't be tried
441	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	475	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
…		…
443		477
444	It is definitely not recommended to use this flag.	478	It is definitely not recommended to use this flag.
445		479
446	=back	480	=back
447		481
448	If one or more of these are ored into the flags value, then only these	482	If one or more of these are or'ed into the flags value, then only these
449	backends will be tried (in the reverse order as listed here). If none are	483	backends will be tried (in the reverse order as listed here). If none are
450	specified, all backends in C<ev_recommended_backends ()> will be tried.	484	specified, all backends in C<ev_recommended_backends ()> will be tried.
451		485
452	The most typical usage is like this:	486	The most typical usage is like this:
453		487
454	if (!ev_default_loop (0))	488	if (!ev_default_loop (0))
455	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	489	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
456		490
457	Restrict libev to the select and poll backends, and do not allow	491	Restrict libev to the select and poll backends, and do not allow
458	environment settings to be taken into account:	492	environment settings to be taken into account:
459		493
460	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);	494	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
461		495
462	Use whatever libev has to offer, but make sure that kqueue is used if	496	Use whatever libev has to offer, but make sure that kqueue is used if
463	available (warning, breaks stuff, best use only with your own private	497	available (warning, breaks stuff, best use only with your own private
464	event loop and only if you know the OS supports your types of fds):	498	event loop and only if you know the OS supports your types of fds):
465		499
466	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	500	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
467		501
468	=item struct ev_loop *ev_loop_new (unsigned int flags)	502	=item struct ev_loop *ev_loop_new (unsigned int flags)
469		503
470	Similar to C<ev_default_loop>, but always creates a new event loop that is	504	Similar to C<ev_default_loop>, but always creates a new event loop that is
471	always distinct from the default loop. Unlike the default loop, it cannot	505	always distinct from the default loop. Unlike the default loop, it cannot
…		…
476	libev with threads is indeed to create one loop per thread, and using the	510	libev with threads is indeed to create one loop per thread, and using the
477	default loop in the "main" or "initial" thread.	511	default loop in the "main" or "initial" thread.
478		512
479	Example: Try to create a event loop that uses epoll and nothing else.	513	Example: Try to create a event loop that uses epoll and nothing else.
480		514
481	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	515	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
482	if (!epoller)	516	if (!epoller)
483	fatal ("no epoll found here, maybe it hides under your chair");	517	fatal ("no epoll found here, maybe it hides under your chair");
484		518
485	=item ev_default_destroy ()	519	=item ev_default_destroy ()
486		520
487	Destroys the default loop again (frees all memory and kernel state	521	Destroys the default loop again (frees all memory and kernel state
488	etc.). None of the active event watchers will be stopped in the normal	522	etc.). None of the active event watchers will be stopped in the normal
489	sense, so e.g. C<ev_is_active> might still return true. It is your	523	sense, so e.g. C<ev_is_active> might still return true. It is your
490	responsibility to either stop all watchers cleanly yoursef I<before>	524	responsibility to either stop all watchers cleanly yourself I<before>
491	calling this function, or cope with the fact afterwards (which is usually	525	calling this function, or cope with the fact afterwards (which is usually
492	the easiest thing, you can just ignore the watchers and/or C<free ()> them	526	the easiest thing, you can just ignore the watchers and/or C<free ()> them
493	for example).	527	for example).
494		528
495	Note that certain global state, such as signal state, will not be freed by	529	Note that certain global state, such as signal state, will not be freed by
…		…
556	received events and started processing them. This timestamp does not	590	received events and started processing them. This timestamp does not
557	change as long as callbacks are being processed, and this is also the base	591	change as long as callbacks are being processed, and this is also the base
558	time used for relative timers. You can treat it as the timestamp of the	592	time used for relative timers. You can treat it as the timestamp of the
559	event occurring (or more correctly, libev finding out about it).	593	event occurring (or more correctly, libev finding out about it).
560		594
		595	=item ev_now_update (loop)
		596
		597	Establishes the current time by querying the kernel, updating the time
		598	returned by C<ev_now ()> in the progress. This is a costly operation and
		599	is usually done automatically within C<ev_loop ()>.
		600
		601	This function is rarely useful, but when some event callback runs for a
		602	very long time without entering the event loop, updating libev's idea of
		603	the current time is a good idea.
		604
		605	See also "The special problem of time updates" in the C<ev_timer> section.
		606
561	=item ev_loop (loop, int flags)	607	=item ev_loop (loop, int flags)
562		608
563	Finally, this is it, the event handler. This function usually is called	609	Finally, this is it, the event handler. This function usually is called
564	after you initialised all your watchers and you want to start handling	610	after you initialised all your watchers and you want to start handling
565	events.	611	events.
…		…
576	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	622	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle
577	those events and any outstanding ones, but will not block your process in	623	those events and any outstanding ones, but will not block your process in
578	case there are no events and will return after one iteration of the loop.	624	case there are no events and will return after one iteration of the loop.
579		625
580	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	626	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
581	neccessary) and will handle those and any outstanding ones. It will block	627	necessary) and will handle those and any outstanding ones. It will block
582	your process until at least one new event arrives, and will return after	628	your process until at least one new event arrives, and will return after
583	one iteration of the loop. This is useful if you are waiting for some	629	one iteration of the loop. This is useful if you are waiting for some
584	external event in conjunction with something not expressible using other	630	external event in conjunction with something not expressible using other
585	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	631	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
586	usually a better approach for this kind of thing.	632	usually a better approach for this kind of thing.
587		633
588	Here are the gory details of what C<ev_loop> does:	634	Here are the gory details of what C<ev_loop> does:
589		635
590	- Before the first iteration, call any pending watchers.	636	- Before the first iteration, call any pending watchers.
591	* If EVFLAG_FORKCHECK was used, check for a fork.	637	* If EVFLAG_FORKCHECK was used, check for a fork.
592	- If a fork was detected, queue and call all fork watchers.	638	- If a fork was detected (by any means), queue and call all fork watchers.
593	- Queue and call all prepare watchers.	639	- Queue and call all prepare watchers.
594	- If we have been forked, recreate the kernel state.	640	- If we have been forked, detach and recreate the kernel state
		641	as to not disturb the other process.
595	- Update the kernel state with all outstanding changes.	642	- Update the kernel state with all outstanding changes.
596	- Update the "event loop time".	643	- Update the "event loop time" (ev_now ()).
597	- Calculate for how long to sleep or block, if at all	644	- Calculate for how long to sleep or block, if at all
598	(active idle watchers, EVLOOP_NONBLOCK or not having	645	(active idle watchers, EVLOOP_NONBLOCK or not having
599	any active watchers at all will result in not sleeping).	646	any active watchers at all will result in not sleeping).
600	- Sleep if the I/O and timer collect interval say so.	647	- Sleep if the I/O and timer collect interval say so.
601	- Block the process, waiting for any events.	648	- Block the process, waiting for any events.
602	- Queue all outstanding I/O (fd) events.	649	- Queue all outstanding I/O (fd) events.
603	- Update the "event loop time" and do time jump handling.	650	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
604	- Queue all outstanding timers.	651	- Queue all outstanding timers.
605	- Queue all outstanding periodics.	652	- Queue all outstanding periodics.
606	- If no events are pending now, queue all idle watchers.	653	- Unless any events are pending now, queue all idle watchers.
607	- Queue all check watchers.	654	- Queue all check watchers.
608	- Call all queued watchers in reverse order (i.e. check watchers first).	655	- Call all queued watchers in reverse order (i.e. check watchers first).
609	Signals and child watchers are implemented as I/O watchers, and will	656	Signals and child watchers are implemented as I/O watchers, and will
610	be handled here by queueing them when their watcher gets executed.	657	be handled here by queueing them when their watcher gets executed.
611	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	658	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
…		…
616	anymore.	663	anymore.
617		664
618	... queue jobs here, make sure they register event watchers as long	665	... queue jobs here, make sure they register event watchers as long
619	... as they still have work to do (even an idle watcher will do..)	666	... as they still have work to do (even an idle watcher will do..)
620	ev_loop (my_loop, 0);	667	ev_loop (my_loop, 0);
621	... jobs done. yeah!	668	... jobs done or somebody called unloop. yeah!
622		669
623	=item ev_unloop (loop, how)	670	=item ev_unloop (loop, how)
624		671
625	Can be used to make a call to C<ev_loop> return early (but only after it	672	Can be used to make a call to C<ev_loop> return early (but only after it
626	has processed all outstanding events). The C<how> argument must be either	673	has processed all outstanding events). The C<how> argument must be either
…		…
647	respectively).	694	respectively).
648		695
649	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	696	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
650	running when nothing else is active.	697	running when nothing else is active.
651		698
652	struct ev_signal exitsig;	699	struct ev_signal exitsig;
653	ev_signal_init (&exitsig, sig_cb, SIGINT);	700	ev_signal_init (&exitsig, sig_cb, SIGINT);
654	ev_signal_start (loop, &exitsig);	701	ev_signal_start (loop, &exitsig);
655	evf_unref (loop);	702	evf_unref (loop);
656		703
657	Example: For some weird reason, unregister the above signal handler again.	704	Example: For some weird reason, unregister the above signal handler again.
658		705
659	ev_ref (loop);	706	ev_ref (loop);
660	ev_signal_stop (loop, &exitsig);	707	ev_signal_stop (loop, &exitsig);
661		708
662	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	709	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
663		710
664	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	711	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
665		712
666	These advanced functions influence the time that libev will spend waiting	713	These advanced functions influence the time that libev will spend waiting
667	for events. Both are by default C<0>, meaning that libev will try to	714	for events. Both time intervals are by default C<0>, meaning that libev
668	invoke timer/periodic callbacks and I/O callbacks with minimum latency.	715	will try to invoke timer/periodic callbacks and I/O callbacks with minimum
		716	latency.
669		717
670	Setting these to a higher value (the C<interval> I<must> be >= C<0>)	718	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
671	allows libev to delay invocation of I/O and timer/periodic callbacks to	719	allows libev to delay invocation of I/O and timer/periodic callbacks
672	increase efficiency of loop iterations.	720	to increase efficiency of loop iterations (or to increase power-saving
		721	opportunities).
673		722
674	The background is that sometimes your program runs just fast enough to	723	The background is that sometimes your program runs just fast enough to
675	handle one (or very few) event(s) per loop iteration. While this makes	724	handle one (or very few) event(s) per loop iteration. While this makes
676	the program responsive, it also wastes a lot of CPU time to poll for new	725	the program responsive, it also wastes a lot of CPU time to poll for new
677	events, especially with backends like C<select ()> which have a high	726	events, especially with backends like C<select ()> which have a high
…		…
687	to spend more time collecting timeouts, at the expense of increased	736	to spend more time collecting timeouts, at the expense of increased
688	latency (the watcher callback will be called later). C<ev_io> watchers	737	latency (the watcher callback will be called later). C<ev_io> watchers
689	will not be affected. Setting this to a non-null value will not introduce	738	will not be affected. Setting this to a non-null value will not introduce
690	any overhead in libev.	739	any overhead in libev.
691		740
692	Many (busy) programs can usually benefit by setting the io collect	741	Many (busy) programs can usually benefit by setting the I/O collect
693	interval to a value near C<0.1> or so, which is often enough for	742	interval to a value near C<0.1> or so, which is often enough for
694	interactive servers (of course not for games), likewise for timeouts. It	743	interactive servers (of course not for games), likewise for timeouts. It
695	usually doesn't make much sense to set it to a lower value than C<0.01>,	744	usually doesn't make much sense to set it to a lower value than C<0.01>,
696	as this approsaches the timing granularity of most systems.	745	as this approaches the timing granularity of most systems.
		746
		747	Setting the I<timeout collect interval> can improve the opportunity for
		748	saving power, as the program will "bundle" timer callback invocations that
		749	are "near" in time together, by delaying some, thus reducing the number of
		750	times the process sleeps and wakes up again. Another useful technique to
		751	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
		752	they fire on, say, one-second boundaries only.
		753
		754	=item ev_loop_verify (loop)
		755
		756	This function only does something when C<EV_VERIFY> support has been
		757	compiled in. It tries to go through all internal structures and checks
		758	them for validity. If anything is found to be inconsistent, it will print
		759	an error message to standard error and call C<abort ()>.
		760
		761	This can be used to catch bugs inside libev itself: under normal
		762	circumstances, this function will never abort as of course libev keeps its
		763	data structures consistent.
697		764
698	=back	765	=back
699		766
700		767
701	=head1 ANATOMY OF A WATCHER	768	=head1 ANATOMY OF A WATCHER
702		769
703	A watcher is a structure that you create and register to record your	770	A watcher is a structure that you create and register to record your
704	interest in some event. For instance, if you want to wait for STDIN to	771	interest in some event. For instance, if you want to wait for STDIN to
705	become readable, you would create an C<ev_io> watcher for that:	772	become readable, you would create an C<ev_io> watcher for that:
706		773
707	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	774	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
708	{	775	{
709	ev_io_stop (w);	776	ev_io_stop (w);
710	ev_unloop (loop, EVUNLOOP_ALL);	777	ev_unloop (loop, EVUNLOOP_ALL);
711	}	778	}
712		779
713	struct ev_loop *loop = ev_default_loop (0);	780	struct ev_loop *loop = ev_default_loop (0);
714	struct ev_io stdin_watcher;	781	struct ev_io stdin_watcher;
715	ev_init (&stdin_watcher, my_cb);	782	ev_init (&stdin_watcher, my_cb);
716	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	783	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
717	ev_io_start (loop, &stdin_watcher);	784	ev_io_start (loop, &stdin_watcher);
718	ev_loop (loop, 0);	785	ev_loop (loop, 0);
719		786
720	As you can see, you are responsible for allocating the memory for your	787	As you can see, you are responsible for allocating the memory for your
721	watcher structures (and it is usually a bad idea to do this on the stack,	788	watcher structures (and it is usually a bad idea to do this on the stack,
722	although this can sometimes be quite valid).	789	although this can sometimes be quite valid).
723		790
724	Each watcher structure must be initialised by a call to C<ev_init	791	Each watcher structure must be initialised by a call to C<ev_init
725	(watcher *, callback)>, which expects a callback to be provided. This	792	(watcher *, callback)>, which expects a callback to be provided. This
726	callback gets invoked each time the event occurs (or, in the case of io	793	callback gets invoked each time the event occurs (or, in the case of I/O
727	watchers, each time the event loop detects that the file descriptor given	794	watchers, each time the event loop detects that the file descriptor given
728	is readable and/or writable).	795	is readable and/or writable).
729		796
730	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	797	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro
731	with arguments specific to this watcher type. There is also a macro	798	with arguments specific to this watcher type. There is also a macro
…		…
807		874
808	The given async watcher has been asynchronously notified (see C<ev_async>).	875	The given async watcher has been asynchronously notified (see C<ev_async>).
809		876
810	=item C<EV_ERROR>	877	=item C<EV_ERROR>
811		878
812	An unspecified error has occured, the watcher has been stopped. This might	879	An unspecified error has occurred, the watcher has been stopped. This might
813	happen because the watcher could not be properly started because libev	880	happen because the watcher could not be properly started because libev
814	ran out of memory, a file descriptor was found to be closed or any other	881	ran out of memory, a file descriptor was found to be closed or any other
815	problem. You best act on it by reporting the problem and somehow coping	882	problem. You best act on it by reporting the problem and somehow coping
816	with the watcher being stopped.	883	with the watcher being stopped.
817		884
818	Libev will usually signal a few "dummy" events together with an error,	885	Libev will usually signal a few "dummy" events together with an error,
819	for example it might indicate that a fd is readable or writable, and if	886	for example it might indicate that a fd is readable or writable, and if
820	your callbacks is well-written it can just attempt the operation and cope	887	your callbacks is well-written it can just attempt the operation and cope
821	with the error from read() or write(). This will not work in multithreaded	888	with the error from read() or write(). This will not work in multi-threaded
822	programs, though, so beware.	889	programs, though, so beware.
823		890
824	=back	891	=back
825		892
826	=head2 GENERIC WATCHER FUNCTIONS	893	=head2 GENERIC WATCHER FUNCTIONS
…		…
856	Although some watcher types do not have type-specific arguments	923	Although some watcher types do not have type-specific arguments
857	(e.g. C<ev_prepare>) you still need to call its C<set> macro.	924	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
858		925
859	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	926	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
860		927
861	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	928	This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
862	calls into a single call. This is the most convinient method to initialise	929	calls into a single call. This is the most convenient method to initialise
863	a watcher. The same limitations apply, of course.	930	a watcher. The same limitations apply, of course.
864		931
865	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	932	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
866		933
867	Starts (activates) the given watcher. Only active watchers will receive	934	Starts (activates) the given watcher. Only active watchers will receive
…		…
950	to associate arbitrary data with your watcher. If you need more data and	1017	to associate arbitrary data with your watcher. If you need more data and
951	don't want to allocate memory and store a pointer to it in that data	1018	don't want to allocate memory and store a pointer to it in that data
952	member, you can also "subclass" the watcher type and provide your own	1019	member, you can also "subclass" the watcher type and provide your own
953	data:	1020	data:
954		1021
955	struct my_io	1022	struct my_io
956	{	1023	{
957	struct ev_io io;	1024	struct ev_io io;
958	int otherfd;	1025	int otherfd;
959	void *somedata;	1026	void *somedata;
960	struct whatever *mostinteresting;	1027	struct whatever *mostinteresting;
961	}	1028	};
		1029
		1030	...
		1031	struct my_io w;
		1032	ev_io_init (&w.io, my_cb, fd, EV_READ);
962		1033
963	And since your callback will be called with a pointer to the watcher, you	1034	And since your callback will be called with a pointer to the watcher, you
964	can cast it back to your own type:	1035	can cast it back to your own type:
965		1036
966	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	1037	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
967	{	1038	{
968	struct my_io *w = (struct my_io *)w_;	1039	struct my_io *w = (struct my_io *)w_;
969	...	1040	...
970	}	1041	}
971		1042
972	More interesting and less C-conformant ways of casting your callback type	1043	More interesting and less C-conformant ways of casting your callback type
973	instead have been omitted.	1044	instead have been omitted.
974		1045
975	Another common scenario is having some data structure with multiple	1046	Another common scenario is to use some data structure with multiple
976	watchers:	1047	embedded watchers:
977		1048
978	struct my_biggy	1049	struct my_biggy
979	{	1050	{
980	int some_data;	1051	int some_data;
981	ev_timer t1;	1052	ev_timer t1;
982	ev_timer t2;	1053	ev_timer t2;
983	}	1054	}
984		1055
985	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1056	In this case getting the pointer to C<my_biggy> is a bit more
986	you need to use C<offsetof>:	1057	complicated: Either you store the address of your C<my_biggy> struct
		1058	in the C<data> member of the watcher, or you need to use some pointer
		1059	arithmetic using C<offsetof> inside your watchers:
987		1060
988	#include <stddef.h>	1061	#include <stddef.h>
989		1062
990	static void	1063	static void
991	t1_cb (EV_P_ struct ev_timer *w, int revents)	1064	t1_cb (EV_P_ struct ev_timer *w, int revents)
992	{	1065	{
993	struct my_biggy big = (struct my_biggy *	1066	struct my_biggy big = (struct my_biggy *
994	(((char *)w) - offsetof (struct my_biggy, t1));	1067	(((char *)w) - offsetof (struct my_biggy, t1));
995	}	1068	}
996		1069
997	static void	1070	static void
998	t2_cb (EV_P_ struct ev_timer *w, int revents)	1071	t2_cb (EV_P_ struct ev_timer *w, int revents)
999	{	1072	{
1000	struct my_biggy big = (struct my_biggy *	1073	struct my_biggy big = (struct my_biggy *
1001	(((char *)w) - offsetof (struct my_biggy, t2));	1074	(((char *)w) - offsetof (struct my_biggy, t2));
1002	}	1075	}
1003		1076
1004		1077
1005	=head1 WATCHER TYPES	1078	=head1 WATCHER TYPES
1006		1079
1007	This section describes each watcher in detail, but will not repeat	1080	This section describes each watcher in detail, but will not repeat
…		…
1036	If you must do this, then force the use of a known-to-be-good backend	1109	If you must do this, then force the use of a known-to-be-good backend
1037	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1110	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
1038	C<EVBACKEND_POLL>).	1111	C<EVBACKEND_POLL>).
1039		1112
1040	Another thing you have to watch out for is that it is quite easy to	1113	Another thing you have to watch out for is that it is quite easy to
1041	receive "spurious" readyness notifications, that is your callback might	1114	receive "spurious" readiness notifications, that is your callback might
1042	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1115	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1043	because there is no data. Not only are some backends known to create a	1116	because there is no data. Not only are some backends known to create a
1044	lot of those (for example solaris ports), it is very easy to get into	1117	lot of those (for example Solaris ports), it is very easy to get into
1045	this situation even with a relatively standard program structure. Thus	1118	this situation even with a relatively standard program structure. Thus
1046	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1119	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1047	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1120	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1048		1121
1049	If you cannot run the fd in non-blocking mode (for example you should not	1122	If you cannot run the fd in non-blocking mode (for example you should not
1050	play around with an Xlib connection), then you have to seperately re-test	1123	play around with an Xlib connection), then you have to separately re-test
1051	whether a file descriptor is really ready with a known-to-be good interface	1124	whether a file descriptor is really ready with a known-to-be good interface
1052	such as poll (fortunately in our Xlib example, Xlib already does this on	1125	such as poll (fortunately in our Xlib example, Xlib already does this on
1053	its own, so its quite safe to use).	1126	its own, so its quite safe to use).
1054		1127
1055	=head3 The special problem of disappearing file descriptors	1128	=head3 The special problem of disappearing file descriptors
…		…
1096	C<EVBACKEND_POLL>.	1169	C<EVBACKEND_POLL>.
1097		1170
1098	=head3 The special problem of SIGPIPE	1171	=head3 The special problem of SIGPIPE
1099		1172
1100	While not really specific to libev, it is easy to forget about SIGPIPE:	1173	While not really specific to libev, it is easy to forget about SIGPIPE:
1101	when reading from a pipe whose other end has been closed, your program	1174	when writing to a pipe whose other end has been closed, your program gets
1102	gets send a SIGPIPE, which, by default, aborts your program. For most	1175	send a SIGPIPE, which, by default, aborts your program. For most programs
1103	programs this is sensible behaviour, for daemons, this is usually	1176	this is sensible behaviour, for daemons, this is usually undesirable.
1104	undesirable.
1105		1177
1106	So when you encounter spurious, unexplained daemon exits, make sure you	1178	So when you encounter spurious, unexplained daemon exits, make sure you
1107	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1179	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1108	somewhere, as that would have given you a big clue).	1180	somewhere, as that would have given you a big clue).
1109		1181
…		…
1115	=item ev_io_init (ev_io *, callback, int fd, int events)	1187	=item ev_io_init (ev_io *, callback, int fd, int events)
1116		1188
1117	=item ev_io_set (ev_io *, int fd, int events)	1189	=item ev_io_set (ev_io *, int fd, int events)
1118		1190
1119	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1191	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1120	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1192	receive events for and events is either C<EV_READ>, C<EV_WRITE> or
1121	C<EV_READ | EV_WRITE> to receive the given events.	1193	C<EV_READ | EV_WRITE> to receive the given events.
1122		1194
1123	=item int fd [read-only]	1195	=item int fd [read-only]
1124		1196
1125	The file descriptor being watched.	1197	The file descriptor being watched.
…		…
1134		1206
1135	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1207	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1136	readable, but only once. Since it is likely line-buffered, you could	1208	readable, but only once. Since it is likely line-buffered, you could
1137	attempt to read a whole line in the callback.	1209	attempt to read a whole line in the callback.
1138		1210
1139	static void	1211	static void
1140	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1212	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1141	{	1213	{
1142	ev_io_stop (loop, w);	1214	ev_io_stop (loop, w);
1143	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1215	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1144	}	1216	}
1145		1217
1146	...	1218	...
1147	struct ev_loop *loop = ev_default_init (0);	1219	struct ev_loop *loop = ev_default_init (0);
1148	struct ev_io stdin_readable;	1220	struct ev_io stdin_readable;
1149	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1221	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1150	ev_io_start (loop, &stdin_readable);	1222	ev_io_start (loop, &stdin_readable);
1151	ev_loop (loop, 0);	1223	ev_loop (loop, 0);
1152		1224
1153		1225
1154	=head2 C<ev_timer> - relative and optionally repeating timeouts	1226	=head2 C<ev_timer> - relative and optionally repeating timeouts
1155		1227
1156	Timer watchers are simple relative timers that generate an event after a	1228	Timer watchers are simple relative timers that generate an event after a
1157	given time, and optionally repeating in regular intervals after that.	1229	given time, and optionally repeating in regular intervals after that.
1158		1230
1159	The timers are based on real time, that is, if you register an event that	1231	The timers are based on real time, that is, if you register an event that
1160	times out after an hour and you reset your system clock to last years	1232	times out after an hour and you reset your system clock to January last
1161	time, it will still time out after (roughly) and hour. "Roughly" because	1233	year, it will still time out after (roughly) and hour. "Roughly" because
1162	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1234	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1163	monotonic clock option helps a lot here).	1235	monotonic clock option helps a lot here).
		1236
		1237	The callback is guaranteed to be invoked only after its timeout has passed,
		1238	but if multiple timers become ready during the same loop iteration then
		1239	order of execution is undefined.
		1240
		1241	=head3 The special problem of time updates
		1242
		1243	Establishing the current time is a costly operation (it usually takes at
		1244	least two system calls): EV therefore updates its idea of the current
		1245	time only before and after C<ev_loop> polls for new events, which causes
		1246	a growing difference between C<ev_now ()> and C<ev_time ()> when handling
		1247	lots of events.
1164		1248
1165	The relative timeouts are calculated relative to the C<ev_now ()>	1249	The relative timeouts are calculated relative to the C<ev_now ()>
1166	time. This is usually the right thing as this timestamp refers to the time	1250	time. This is usually the right thing as this timestamp refers to the time
1167	of the event triggering whatever timeout you are modifying/starting. If	1251	of the event triggering whatever timeout you are modifying/starting. If
1168	you suspect event processing to be delayed and you I<need> to base the timeout	1252	you suspect event processing to be delayed and you I<need> to base the
1169	on the current time, use something like this to adjust for this:	1253	timeout on the current time, use something like this to adjust for this:
1170		1254
1171	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1255	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1172		1256
1173	The callback is guarenteed to be invoked only when its timeout has passed,	1257	If the event loop is suspended for a long time, you can also force an
1174	but if multiple timers become ready during the same loop iteration then	1258	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1175	order of execution is undefined.	1259	()>.
1176		1260
1177	=head3 Watcher-Specific Functions and Data Members	1261	=head3 Watcher-Specific Functions and Data Members
1178		1262
1179	=over 4	1263	=over 4
1180		1264
1181	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1265	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1182		1266
1183	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1267	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1184		1268
1185	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1269	Configure the timer to trigger after C<after> seconds. If C<repeat>
1186	C<0.>, then it will automatically be stopped. If it is positive, then the	1270	is C<0.>, then it will automatically be stopped once the timeout is
1187	timer will automatically be configured to trigger again C<repeat> seconds	1271	reached. If it is positive, then the timer will automatically be
1188	later, again, and again, until stopped manually.	1272	configured to trigger again C<repeat> seconds later, again, and again,
		1273	until stopped manually.
1189		1274
1190	The timer itself will do a best-effort at avoiding drift, that is, if you	1275	The timer itself will do a best-effort at avoiding drift, that is, if
1191	configure a timer to trigger every 10 seconds, then it will trigger at	1276	you configure a timer to trigger every 10 seconds, then it will normally
1192	exactly 10 second intervals. If, however, your program cannot keep up with	1277	trigger at exactly 10 second intervals. If, however, your program cannot
1193	the timer (because it takes longer than those 10 seconds to do stuff) the	1278	keep up with the timer (because it takes longer than those 10 seconds to
1194	timer will not fire more than once per event loop iteration.	1279	do stuff) the timer will not fire more than once per event loop iteration.
1195		1280
1196	=item ev_timer_again (loop, ev_timer *)	1281	=item ev_timer_again (loop, ev_timer *)
1197		1282
1198	This will act as if the timer timed out and restart it again if it is	1283	This will act as if the timer timed out and restart it again if it is
1199	repeating. The exact semantics are:	1284	repeating. The exact semantics are:
1200		1285
1201	If the timer is pending, its pending status is cleared.	1286	If the timer is pending, its pending status is cleared.
1202		1287
1203	If the timer is started but nonrepeating, stop it (as if it timed out).	1288	If the timer is started but non-repeating, stop it (as if it timed out).
1204		1289
1205	If the timer is repeating, either start it if necessary (with the	1290	If the timer is repeating, either start it if necessary (with the
1206	C<repeat> value), or reset the running timer to the C<repeat> value.	1291	C<repeat> value), or reset the running timer to the C<repeat> value.
1207		1292
1208	This sounds a bit complicated, but here is a useful and typical	1293	This sounds a bit complicated, but here is a useful and typical
1209	example: Imagine you have a tcp connection and you want a so-called idle	1294	example: Imagine you have a TCP connection and you want a so-called idle
1210	timeout, that is, you want to be called when there have been, say, 60	1295	timeout, that is, you want to be called when there have been, say, 60
1211	seconds of inactivity on the socket. The easiest way to do this is to	1296	seconds of inactivity on the socket. The easiest way to do this is to
1212	configure an C<ev_timer> with a C<repeat> value of C<60> and then call	1297	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1213	C<ev_timer_again> each time you successfully read or write some data. If	1298	C<ev_timer_again> each time you successfully read or write some data. If
1214	you go into an idle state where you do not expect data to travel on the	1299	you go into an idle state where you do not expect data to travel on the
…		…
1240		1325
1241	=head3 Examples	1326	=head3 Examples
1242		1327
1243	Example: Create a timer that fires after 60 seconds.	1328	Example: Create a timer that fires after 60 seconds.
1244		1329
1245	static void	1330	static void
1246	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1331	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1247	{	1332	{
1248	.. one minute over, w is actually stopped right here	1333	.. one minute over, w is actually stopped right here
1249	}	1334	}
1250		1335
1251	struct ev_timer mytimer;	1336	struct ev_timer mytimer;
1252	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1337	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1253	ev_timer_start (loop, &mytimer);	1338	ev_timer_start (loop, &mytimer);
1254		1339
1255	Example: Create a timeout timer that times out after 10 seconds of	1340	Example: Create a timeout timer that times out after 10 seconds of
1256	inactivity.	1341	inactivity.
1257		1342
1258	static void	1343	static void
1259	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1344	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1260	{	1345	{
1261	.. ten seconds without any activity	1346	.. ten seconds without any activity
1262	}	1347	}
1263		1348
1264	struct ev_timer mytimer;	1349	struct ev_timer mytimer;
1265	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1350	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1266	ev_timer_again (&mytimer); /* start timer */	1351	ev_timer_again (&mytimer); /* start timer */
1267	ev_loop (loop, 0);	1352	ev_loop (loop, 0);
1268		1353
1269	// and in some piece of code that gets executed on any "activity":	1354	// and in some piece of code that gets executed on any "activity":
1270	// reset the timeout to start ticking again at 10 seconds	1355	// reset the timeout to start ticking again at 10 seconds
1271	ev_timer_again (&mytimer);	1356	ev_timer_again (&mytimer);
1272		1357
1273		1358
1274	=head2 C<ev_periodic> - to cron or not to cron?	1359	=head2 C<ev_periodic> - to cron or not to cron?
1275		1360
1276	Periodic watchers are also timers of a kind, but they are very versatile	1361	Periodic watchers are also timers of a kind, but they are very versatile
1277	(and unfortunately a bit complex).	1362	(and unfortunately a bit complex).
1278		1363
1279	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1364	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
1280	but on wallclock time (absolute time). You can tell a periodic watcher	1365	but on wall clock time (absolute time). You can tell a periodic watcher
1281	to trigger "at" some specific point in time. For example, if you tell a	1366	to trigger after some specific point in time. For example, if you tell a
1282	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1367	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()
1283	+ 10.>) and then reset your system clock to the last year, then it will	1368	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1369	clock to January of the previous year, then it will take more than year
1284	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1370	to trigger the event (unlike an C<ev_timer>, which would still trigger
1285	roughly 10 seconds later).	1371	roughly 10 seconds later as it uses a relative timeout).
1286		1372
1287	They can also be used to implement vastly more complex timers, such as	1373	C<ev_periodic>s can also be used to implement vastly more complex timers,
1288	triggering an event on each midnight, local time or other, complicated,	1374	such as triggering an event on each "midnight, local time", or other
1289	rules.	1375	complicated, rules.
1290		1376
1291	As with timers, the callback is guarenteed to be invoked only when the	1377	As with timers, the callback is guaranteed to be invoked only when the
1292	time (C<at>) has been passed, but if multiple periodic timers become ready	1378	time (C<at>) has passed, but if multiple periodic timers become ready
1293	during the same loop iteration then order of execution is undefined.	1379	during the same loop iteration then order of execution is undefined.
1294		1380
1295	=head3 Watcher-Specific Functions and Data Members	1381	=head3 Watcher-Specific Functions and Data Members
1296		1382
1297	=over 4	1383	=over 4
…		…
1305		1391
1306	=over 4	1392	=over 4
1307		1393
1308	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1394	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1309		1395
1310	In this configuration the watcher triggers an event at the wallclock time	1396	In this configuration the watcher triggers an event after the wall clock
1311	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1397	time C<at> has passed and doesn't repeat. It will not adjust when a time
1312	that is, if it is to be run at January 1st 2011 then it will run when the	1398	jump occurs, that is, if it is to be run at January 1st 2011 then it will
1313	system time reaches or surpasses this time.	1399	run when the system time reaches or surpasses this time.
1314		1400
1315	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1401	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1316		1402
1317	In this mode the watcher will always be scheduled to time out at the next	1403	In this mode the watcher will always be scheduled to time out at the next
1318	C<at + N * interval> time (for some integer N, which can also be negative)	1404	C<at + N * interval> time (for some integer N, which can also be negative)
1319	and then repeat, regardless of any time jumps.	1405	and then repeat, regardless of any time jumps.
1320		1406
1321	This can be used to create timers that do not drift with respect to system	1407	This can be used to create timers that do not drift with respect to system
1322	time:	1408	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1409	the hour:
1323		1410
1324	ev_periodic_set (&periodic, 0., 3600., 0);	1411	ev_periodic_set (&periodic, 0., 3600., 0);
1325		1412
1326	This doesn't mean there will always be 3600 seconds in between triggers,	1413	This doesn't mean there will always be 3600 seconds in between triggers,
1327	but only that the the callback will be called when the system time shows a	1414	but only that the callback will be called when the system time shows a
1328	full hour (UTC), or more correctly, when the system time is evenly divisible	1415	full hour (UTC), or more correctly, when the system time is evenly divisible
1329	by 3600.	1416	by 3600.
1330		1417
1331	Another way to think about it (for the mathematically inclined) is that	1418	Another way to think about it (for the mathematically inclined) is that
1332	C<ev_periodic> will try to run the callback in this mode at the next possible	1419	C<ev_periodic> will try to run the callback in this mode at the next possible
1333	time where C<time = at (mod interval)>, regardless of any time jumps.	1420	time where C<time = at (mod interval)>, regardless of any time jumps.
1334		1421
1335	For numerical stability it is preferable that the C<at> value is near	1422	For numerical stability it is preferable that the C<at> value is near
1336	C<ev_now ()> (the current time), but there is no range requirement for	1423	C<ev_now ()> (the current time), but there is no range requirement for
1337	this value.	1424	this value, and in fact is often specified as zero.
		1425
		1426	Note also that there is an upper limit to how often a timer can fire (CPU
		1427	speed for example), so if C<interval> is very small then timing stability
		1428	will of course deteriorate. Libev itself tries to be exact to be about one
		1429	millisecond (if the OS supports it and the machine is fast enough).
1338		1430
1339	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1431	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1340		1432
1341	In this mode the values for C<interval> and C<at> are both being	1433	In this mode the values for C<interval> and C<at> are both being
1342	ignored. Instead, each time the periodic watcher gets scheduled, the	1434	ignored. Instead, each time the periodic watcher gets scheduled, the
1343	reschedule callback will be called with the watcher as first, and the	1435	reschedule callback will be called with the watcher as first, and the
1344	current time as second argument.	1436	current time as second argument.
1345		1437
1346	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1438	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1347	ever, or make any event loop modifications>. If you need to stop it,	1439	ever, or make ANY event loop modifications whatsoever>.
1348	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1349	starting an C<ev_prepare> watcher, which is legal).
1350		1440
		1441	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1442	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1443	only event loop modification you are allowed to do).
		1444
1351	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1445	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1352	ev_tstamp now)>, e.g.:	1446	*w, ev_tstamp now)>, e.g.:
1353		1447
1354	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1448	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1355	{	1449	{
1356	return now + 60.;	1450	return now + 60.;
1357	}	1451	}
…		…
1359	It must return the next time to trigger, based on the passed time value	1453	It must return the next time to trigger, based on the passed time value
1360	(that is, the lowest time value larger than to the second argument). It	1454	(that is, the lowest time value larger than to the second argument). It
1361	will usually be called just before the callback will be triggered, but	1455	will usually be called just before the callback will be triggered, but
1362	might be called at other times, too.	1456	might be called at other times, too.
1363		1457
1364	NOTE: I<< This callback must always return a time that is later than the	1458	NOTE: I<< This callback must always return a time that is higher than or
1365	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.	1459	equal to the passed C<now> value >>.
1366		1460
1367	This can be used to create very complex timers, such as a timer that	1461	This can be used to create very complex timers, such as a timer that
1368	triggers on each midnight, local time. To do this, you would calculate the	1462	triggers on "next midnight, local time". To do this, you would calculate the
1369	next midnight after C<now> and return the timestamp value for this. How	1463	next midnight after C<now> and return the timestamp value for this. How
1370	you do this is, again, up to you (but it is not trivial, which is the main	1464	you do this is, again, up to you (but it is not trivial, which is the main
1371	reason I omitted it as an example).	1465	reason I omitted it as an example).
1372		1466
1373	=back	1467	=back
…		…
1377	Simply stops and restarts the periodic watcher again. This is only useful	1471	Simply stops and restarts the periodic watcher again. This is only useful
1378	when you changed some parameters or the reschedule callback would return	1472	when you changed some parameters or the reschedule callback would return
1379	a different time than the last time it was called (e.g. in a crond like	1473	a different time than the last time it was called (e.g. in a crond like
1380	program when the crontabs have changed).	1474	program when the crontabs have changed).
1381		1475
		1476	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1477
		1478	When active, returns the absolute time that the watcher is supposed to
		1479	trigger next.
		1480
1382	=item ev_tstamp offset [read-write]	1481	=item ev_tstamp offset [read-write]
1383		1482
1384	When repeating, this contains the offset value, otherwise this is the	1483	When repeating, this contains the offset value, otherwise this is the
1385	absolute point in time (the C<at> value passed to C<ev_periodic_set>).	1484	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1386		1485
…		…
1397		1496
1398	The current reschedule callback, or C<0>, if this functionality is	1497	The current reschedule callback, or C<0>, if this functionality is
1399	switched off. Can be changed any time, but changes only take effect when	1498	switched off. Can be changed any time, but changes only take effect when
1400	the periodic timer fires or C<ev_periodic_again> is being called.	1499	the periodic timer fires or C<ev_periodic_again> is being called.
1401		1500
1402	=item ev_tstamp at [read-only]
1403
1404	When active, contains the absolute time that the watcher is supposed to
1405	trigger next.
1406
1407	=back	1501	=back
1408		1502
1409	=head3 Examples	1503	=head3 Examples
1410		1504
1411	Example: Call a callback every hour, or, more precisely, whenever the	1505	Example: Call a callback every hour, or, more precisely, whenever the
1412	system clock is divisible by 3600. The callback invocation times have	1506	system clock is divisible by 3600. The callback invocation times have
1413	potentially a lot of jittering, but good long-term stability.	1507	potentially a lot of jitter, but good long-term stability.
1414		1508
1415	static void	1509	static void
1416	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1510	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1417	{	1511	{
1418	... its now a full hour (UTC, or TAI or whatever your clock follows)	1512	... its now a full hour (UTC, or TAI or whatever your clock follows)
1419	}	1513	}
1420		1514
1421	struct ev_periodic hourly_tick;	1515	struct ev_periodic hourly_tick;
1422	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1516	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1423	ev_periodic_start (loop, &hourly_tick);	1517	ev_periodic_start (loop, &hourly_tick);
1424		1518
1425	Example: The same as above, but use a reschedule callback to do it:	1519	Example: The same as above, but use a reschedule callback to do it:
1426		1520
1427	#include <math.h>	1521	#include <math.h>
1428		1522
1429	static ev_tstamp	1523	static ev_tstamp
1430	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1524	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1431	{	1525	{
1432	return fmod (now, 3600.) + 3600.;	1526	return fmod (now, 3600.) + 3600.;
1433	}	1527	}
1434		1528
1435	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1529	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1436		1530
1437	Example: Call a callback every hour, starting now:	1531	Example: Call a callback every hour, starting now:
1438		1532
1439	struct ev_periodic hourly_tick;	1533	struct ev_periodic hourly_tick;
1440	ev_periodic_init (&hourly_tick, clock_cb,	1534	ev_periodic_init (&hourly_tick, clock_cb,
1441	fmod (ev_now (loop), 3600.), 3600., 0);	1535	fmod (ev_now (loop), 3600.), 3600., 0);
1442	ev_periodic_start (loop, &hourly_tick);	1536	ev_periodic_start (loop, &hourly_tick);
1443		1537
1444		1538
1445	=head2 C<ev_signal> - signal me when a signal gets signalled!	1539	=head2 C<ev_signal> - signal me when a signal gets signalled!
1446		1540
1447	Signal watchers will trigger an event when the process receives a specific	1541	Signal watchers will trigger an event when the process receives a specific
…		…
1455	as you don't register any with libev). Similarly, when the last signal	1549	as you don't register any with libev). Similarly, when the last signal
1456	watcher for a signal is stopped libev will reset the signal handler to	1550	watcher for a signal is stopped libev will reset the signal handler to
1457	SIG_DFL (regardless of what it was set to before).	1551	SIG_DFL (regardless of what it was set to before).
1458		1552
1459	If possible and supported, libev will install its handlers with	1553	If possible and supported, libev will install its handlers with
1460	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1554	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1461	interrupted. If you have a problem with syscalls getting interrupted by	1555	interrupted. If you have a problem with system calls getting interrupted by
1462	signals you can block all signals in an C<ev_check> watcher and unblock	1556	signals you can block all signals in an C<ev_check> watcher and unblock
1463	them in an C<ev_prepare> watcher.	1557	them in an C<ev_prepare> watcher.
1464		1558
1465	=head3 Watcher-Specific Functions and Data Members	1559	=head3 Watcher-Specific Functions and Data Members
1466		1560
…		…
1481		1575
1482	=head3 Examples	1576	=head3 Examples
1483		1577
1484	Example: Try to exit cleanly on SIGINT and SIGTERM.	1578	Example: Try to exit cleanly on SIGINT and SIGTERM.
1485		1579
1486	static void	1580	static void
1487	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1581	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1488	{	1582	{
1489	ev_unloop (loop, EVUNLOOP_ALL);	1583	ev_unloop (loop, EVUNLOOP_ALL);
1490	}	1584	}
1491		1585
1492	struct ev_signal signal_watcher;	1586	struct ev_signal signal_watcher;
1493	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1587	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1494	ev_signal_start (loop, &sigint_cb);	1588	ev_signal_start (loop, &sigint_cb);
1495		1589
1496		1590
1497	=head2 C<ev_child> - watch out for process status changes	1591	=head2 C<ev_child> - watch out for process status changes
1498		1592
1499	Child watchers trigger when your process receives a SIGCHLD in response to	1593	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1501	is permissible to install a child watcher I<after> the child has been	1595	is permissible to install a child watcher I<after> the child has been
1502	forked (which implies it might have already exited), as long as the event	1596	forked (which implies it might have already exited), as long as the event
1503	loop isn't entered (or is continued from a watcher).	1597	loop isn't entered (or is continued from a watcher).
1504		1598
1505	Only the default event loop is capable of handling signals, and therefore	1599	Only the default event loop is capable of handling signals, and therefore
1506	you can only rgeister child watchers in the default event loop.	1600	you can only register child watchers in the default event loop.
1507		1601
1508	=head3 Process Interaction	1602	=head3 Process Interaction
1509		1603
1510	Libev grabs C<SIGCHLD> as soon as the default event loop is	1604	Libev grabs C<SIGCHLD> as soon as the default event loop is
1511	initialised. This is necessary to guarantee proper behaviour even if	1605	initialised. This is necessary to guarantee proper behaviour even if
1512	the first child watcher is started after the child exits. The occurance	1606	the first child watcher is started after the child exits. The occurrence
1513	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1607	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1514	synchronously as part of the event loop processing. Libev always reaps all	1608	synchronously as part of the event loop processing. Libev always reaps all
1515	children, even ones not watched.	1609	children, even ones not watched.
1516		1610
1517	=head3 Overriding the Built-In Processing	1611	=head3 Overriding the Built-In Processing
…		…
1521	handler, you can override it easily by installing your own handler for	1615	handler, you can override it easily by installing your own handler for
1522	C<SIGCHLD> after initialising the default loop, and making sure the	1616	C<SIGCHLD> after initialising the default loop, and making sure the
1523	default loop never gets destroyed. You are encouraged, however, to use an	1617	default loop never gets destroyed. You are encouraged, however, to use an
1524	event-based approach to child reaping and thus use libev's support for	1618	event-based approach to child reaping and thus use libev's support for
1525	that, so other libev users can use C<ev_child> watchers freely.	1619	that, so other libev users can use C<ev_child> watchers freely.
		1620
		1621	=head3 Stopping the Child Watcher
		1622
		1623	Currently, the child watcher never gets stopped, even when the
		1624	child terminates, so normally one needs to stop the watcher in the
		1625	callback. Future versions of libev might stop the watcher automatically
		1626	when a child exit is detected.
1526		1627
1527	=head3 Watcher-Specific Functions and Data Members	1628	=head3 Watcher-Specific Functions and Data Members
1528		1629
1529	=over 4	1630	=over 4
1530		1631
…		…
1559	=head3 Examples	1660	=head3 Examples
1560		1661
1561	Example: C<fork()> a new process and install a child handler to wait for	1662	Example: C<fork()> a new process and install a child handler to wait for
1562	its completion.	1663	its completion.
1563		1664
1564	ev_child cw;	1665	ev_child cw;
1565		1666
1566	static void	1667	static void
1567	child_cb (EV_P_ struct ev_child *w, int revents)	1668	child_cb (EV_P_ struct ev_child *w, int revents)
1568	{	1669	{
1569	ev_child_stop (EV_A_ w);	1670	ev_child_stop (EV_A_ w);
1570	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1671	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1571	}	1672	}
1572		1673
1573	pid_t pid = fork ();	1674	pid_t pid = fork ();
1574		1675
1575	if (pid < 0)	1676	if (pid < 0)
1576	// error	1677	// error
1577	else if (pid == 0)	1678	else if (pid == 0)
1578	{	1679	{
1579	// the forked child executes here	1680	// the forked child executes here
1580	exit (1);	1681	exit (1);
1581	}	1682	}
1582	else	1683	else
1583	{	1684	{
1584	ev_child_init (&cw, child_cb, pid, 0);	1685	ev_child_init (&cw, child_cb, pid, 0);
1585	ev_child_start (EV_DEFAULT_ &cw);	1686	ev_child_start (EV_DEFAULT_ &cw);
1586	}	1687	}
1587		1688
1588		1689
1589	=head2 C<ev_stat> - did the file attributes just change?	1690	=head2 C<ev_stat> - did the file attributes just change?
1590		1691
1591	This watches a filesystem path for attribute changes. That is, it calls	1692	This watches a file system path for attribute changes. That is, it calls
1592	C<stat> regularly (or when the OS says it changed) and sees if it changed	1693	C<stat> regularly (or when the OS says it changed) and sees if it changed
1593	compared to the last time, invoking the callback if it did.	1694	compared to the last time, invoking the callback if it did.
1594		1695
1595	The path does not need to exist: changing from "path exists" to "path does	1696	The path does not need to exist: changing from "path exists" to "path does
1596	not exist" is a status change like any other. The condition "path does	1697	not exist" is a status change like any other. The condition "path does
…		…
1614	as even with OS-supported change notifications, this can be	1715	as even with OS-supported change notifications, this can be
1615	resource-intensive.	1716	resource-intensive.
1616		1717
1617	At the time of this writing, only the Linux inotify interface is	1718	At the time of this writing, only the Linux inotify interface is
1618	implemented (implementing kqueue support is left as an exercise for the	1719	implemented (implementing kqueue support is left as an exercise for the
		1720	reader, note, however, that the author sees no way of implementing ev_stat
1619	reader). Inotify will be used to give hints only and should not change the	1721	semantics with kqueue). Inotify will be used to give hints only and should
1620	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1722	not change the semantics of C<ev_stat> watchers, which means that libev
1621	to fall back to regular polling again even with inotify, but changes are	1723	sometimes needs to fall back to regular polling again even with inotify,
1622	usually detected immediately, and if the file exists there will be no	1724	but changes are usually detected immediately, and if the file exists there
1623	polling.	1725	will be no polling.
1624		1726
1625	=head3 ABI Issues (Largefile Support)	1727	=head3 ABI Issues (Largefile Support)
1626		1728
1627	Libev by default (unless the user overrides this) uses the default	1729	Libev by default (unless the user overrides this) uses the default
1628	compilation environment, which means that on systems with optionally	1730	compilation environment, which means that on systems with large file
1629	disabled large file support, you get the 32 bit version of the stat	1731	support disabled by default, you get the 32 bit version of the stat
1630	structure. When using the library from programs that change the ABI to	1732	structure. When using the library from programs that change the ABI to
1631	use 64 bit file offsets the programs will fail. In that case you have to	1733	use 64 bit file offsets the programs will fail. In that case you have to
1632	compile libev with the same flags to get binary compatibility. This is	1734	compile libev with the same flags to get binary compatibility. This is
1633	obviously the case with any flags that change the ABI, but the problem is	1735	obviously the case with any flags that change the ABI, but the problem is
1634	most noticably with ev_stat and largefile support.	1736	most noticeably disabled with ev_stat and large file support.
		1737
		1738	The solution for this is to lobby your distribution maker to make large
		1739	file interfaces available by default (as e.g. FreeBSD does) and not
		1740	optional. Libev cannot simply switch on large file support because it has
		1741	to exchange stat structures with application programs compiled using the
		1742	default compilation environment.
1635		1743
1636	=head3 Inotify	1744	=head3 Inotify
1637		1745
1638	When C<inotify (7)> support has been compiled into libev (generally only	1746	When C<inotify (7)> support has been compiled into libev (generally only
1639	available on Linux) and present at runtime, it will be used to speed up	1747	available on Linux) and present at runtime, it will be used to speed up
1640	change detection where possible. The inotify descriptor will be created lazily	1748	change detection where possible. The inotify descriptor will be created lazily
1641	when the first C<ev_stat> watcher is being started.	1749	when the first C<ev_stat> watcher is being started.
1642		1750
1643	Inotify presense does not change the semantics of C<ev_stat> watchers	1751	Inotify presence does not change the semantics of C<ev_stat> watchers
1644	except that changes might be detected earlier, and in some cases, to avoid	1752	except that changes might be detected earlier, and in some cases, to avoid
1645	making regular C<stat> calls. Even in the presense of inotify support	1753	making regular C<stat> calls. Even in the presence of inotify support
1646	there are many cases where libev has to resort to regular C<stat> polling.	1754	there are many cases where libev has to resort to regular C<stat> polling.
1647		1755
1648	(There is no support for kqueue, as apparently it cannot be used to	1756	(There is no support for kqueue, as apparently it cannot be used to
1649	implement this functionality, due to the requirement of having a file	1757	implement this functionality, due to the requirement of having a file
1650	descriptor open on the object at all times).	1758	descriptor open on the object at all times).
1651		1759
1652	=head3 The special problem of stat time resolution	1760	=head3 The special problem of stat time resolution
1653		1761
1654	The C<stat ()> syscall only supports full-second resolution portably, and	1762	The C<stat ()> system call only supports full-second resolution portably, and
1655	even on systems where the resolution is higher, many filesystems still	1763	even on systems where the resolution is higher, many file systems still
1656	only support whole seconds.	1764	only support whole seconds.
1657		1765
1658	That means that, if the time is the only thing that changes, you might	1766	That means that, if the time is the only thing that changes, you can
1659	miss updates: on the first update, C<ev_stat> detects a change and calls	1767	easily miss updates: on the first update, C<ev_stat> detects a change and
1660	your callback, which does something. When there is another update within	1768	calls your callback, which does something. When there is another update
1661	the same second, C<ev_stat> will be unable to detect it.	1769	within the same second, C<ev_stat> will be unable to detect it as the stat
		1770	data does not change.
1662		1771
1663	The solution to this is to delay acting on a change for a second (or till	1772	The solution to this is to delay acting on a change for slightly more
1664	the next second boundary), using a roughly one-second delay C<ev_timer>	1773	than a second (or till slightly after the next full second boundary), using
1665	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>	1774	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);
1666	is added to work around small timing inconsistencies of some operating	1775	ev_timer_again (loop, w)>).
1667	systems.	1776
		1777	The C<.02> offset is added to work around small timing inconsistencies
		1778	of some operating systems (where the second counter of the current time
		1779	might be be delayed. One such system is the Linux kernel, where a call to
		1780	C<gettimeofday> might return a timestamp with a full second later than
		1781	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1782	update file times then there will be a small window where the kernel uses
		1783	the previous second to update file times but libev might already execute
		1784	the timer callback).
1668		1785
1669	=head3 Watcher-Specific Functions and Data Members	1786	=head3 Watcher-Specific Functions and Data Members
1670		1787
1671	=over 4	1788	=over 4
1672		1789
…		…
1678	C<path>. The C<interval> is a hint on how quickly a change is expected to	1795	C<path>. The C<interval> is a hint on how quickly a change is expected to
1679	be detected and should normally be specified as C<0> to let libev choose	1796	be detected and should normally be specified as C<0> to let libev choose
1680	a suitable value. The memory pointed to by C<path> must point to the same	1797	a suitable value. The memory pointed to by C<path> must point to the same
1681	path for as long as the watcher is active.	1798	path for as long as the watcher is active.
1682		1799
1683	The callback will be receive C<EV_STAT> when a change was detected,	1800	The callback will receive C<EV_STAT> when a change was detected, relative
1684	relative to the attributes at the time the watcher was started (or the	1801	to the attributes at the time the watcher was started (or the last change
1685	last change was detected).	1802	was detected).
1686		1803
1687	=item ev_stat_stat (loop, ev_stat *)	1804	=item ev_stat_stat (loop, ev_stat *)
1688		1805
1689	Updates the stat buffer immediately with new values. If you change the	1806	Updates the stat buffer immediately with new values. If you change the
1690	watched path in your callback, you could call this fucntion to avoid	1807	watched path in your callback, you could call this function to avoid
1691	detecting this change (while introducing a race condition). Can also be	1808	detecting this change (while introducing a race condition if you are not
1692	useful simply to find out the new values.	1809	the only one changing the path). Can also be useful simply to find out the
		1810	new values.
1693		1811
1694	=item ev_statdata attr [read-only]	1812	=item ev_statdata attr [read-only]
1695		1813
1696	The most-recently detected attributes of the file. Although the type is of	1814	The most-recently detected attributes of the file. Although the type is
1697	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types	1815	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
1698	suitable for your system. If the C<st_nlink> member is C<0>, then there	1816	suitable for your system, but you can only rely on the POSIX-standardised
		1817	members to be present. If the C<st_nlink> member is C<0>, then there was
1699	was some error while C<stat>ing the file.	1818	some error while C<stat>ing the file.
1700		1819
1701	=item ev_statdata prev [read-only]	1820	=item ev_statdata prev [read-only]
1702		1821
1703	The previous attributes of the file. The callback gets invoked whenever	1822	The previous attributes of the file. The callback gets invoked whenever
1704	C<prev> != C<attr>.	1823	C<prev> != C<attr>, or, more precisely, one or more of these members
		1824	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1825	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1705		1826
1706	=item ev_tstamp interval [read-only]	1827	=item ev_tstamp interval [read-only]
1707		1828
1708	The specified interval.	1829	The specified interval.
1709		1830
1710	=item const char *path [read-only]	1831	=item const char *path [read-only]
1711		1832
1712	The filesystem path that is being watched.	1833	The file system path that is being watched.
1713		1834
1714	=back	1835	=back
1715		1836
1716	=head3 Examples	1837	=head3 Examples
1717		1838
1718	Example: Watch C</etc/passwd> for attribute changes.	1839	Example: Watch C</etc/passwd> for attribute changes.
1719		1840
1720	static void	1841	static void
1721	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1842	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1722	{	1843	{
1723	/* /etc/passwd changed in some way */	1844	/* /etc/passwd changed in some way */
1724	if (w->attr.st_nlink)	1845	if (w->attr.st_nlink)
1725	{	1846	{
1726	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1847	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1727	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1848	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1728	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1849	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1729	}	1850	}
1730	else	1851	else
1731	/* you shalt not abuse printf for puts */	1852	/* you shalt not abuse printf for puts */
1732	puts ("wow, /etc/passwd is not there, expect problems. "	1853	puts ("wow, /etc/passwd is not there, expect problems. "
1733	"if this is windows, they already arrived\n");	1854	"if this is windows, they already arrived\n");
1734	}	1855	}
1735		1856
1736	...	1857	...
1737	ev_stat passwd;	1858	ev_stat passwd;
1738		1859
1739	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1860	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1740	ev_stat_start (loop, &passwd);	1861	ev_stat_start (loop, &passwd);
1741		1862
1742	Example: Like above, but additionally use a one-second delay so we do not	1863	Example: Like above, but additionally use a one-second delay so we do not
1743	miss updates (however, frequent updates will delay processing, too, so	1864	miss updates (however, frequent updates will delay processing, too, so
1744	one might do the work both on C<ev_stat> callback invocation I<and> on	1865	one might do the work both on C<ev_stat> callback invocation I<and> on
1745	C<ev_timer> callback invocation).	1866	C<ev_timer> callback invocation).
1746		1867
1747	static ev_stat passwd;	1868	static ev_stat passwd;
1748	static ev_timer timer;	1869	static ev_timer timer;
1749		1870
1750	static void	1871	static void
1751	timer_cb (EV_P_ ev_timer *w, int revents)	1872	timer_cb (EV_P_ ev_timer *w, int revents)
1752	{	1873	{
1753	ev_timer_stop (EV_A_ w);	1874	ev_timer_stop (EV_A_ w);
1754		1875
1755	/* now it's one second after the most recent passwd change */	1876	/* now it's one second after the most recent passwd change */
1756	}	1877	}
1757		1878
1758	static void	1879	static void
1759	stat_cb (EV_P_ ev_stat *w, int revents)	1880	stat_cb (EV_P_ ev_stat *w, int revents)
1760	{	1881	{
1761	/* reset the one-second timer */	1882	/* reset the one-second timer */
1762	ev_timer_again (EV_A_ &timer);	1883	ev_timer_again (EV_A_ &timer);
1763	}	1884	}
1764		1885
1765	...	1886	...
1766	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1887	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1767	ev_stat_start (loop, &passwd);	1888	ev_stat_start (loop, &passwd);
1768	ev_timer_init (&timer, timer_cb, 0., 1.01);	1889	ev_timer_init (&timer, timer_cb, 0., 1.02);
1769		1890
1770		1891
1771	=head2 C<ev_idle> - when you've got nothing better to do...	1892	=head2 C<ev_idle> - when you've got nothing better to do...
1772		1893
1773	Idle watchers trigger events when no other events of the same or higher	1894	Idle watchers trigger events when no other events of the same or higher
…		…
1804	=head3 Examples	1925	=head3 Examples
1805		1926
1806	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1927	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1807	callback, free it. Also, use no error checking, as usual.	1928	callback, free it. Also, use no error checking, as usual.
1808		1929
1809	static void	1930	static void
1810	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1931	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1811	{	1932	{
1812	free (w);	1933	free (w);
1813	// now do something you wanted to do when the program has	1934	// now do something you wanted to do when the program has
1814	// no longer anything immediate to do.	1935	// no longer anything immediate to do.
1815	}	1936	}
1816		1937
1817	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1938	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1818	ev_idle_init (idle_watcher, idle_cb);	1939	ev_idle_init (idle_watcher, idle_cb);
1819	ev_idle_start (loop, idle_cb);	1940	ev_idle_start (loop, idle_cb);
1820		1941
1821		1942
1822	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1943	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1823		1944
1824	Prepare and check watchers are usually (but not always) used in tandem:	1945	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1843		1964
1844	This is done by examining in each prepare call which file descriptors need	1965	This is done by examining in each prepare call which file descriptors need
1845	to be watched by the other library, registering C<ev_io> watchers for	1966	to be watched by the other library, registering C<ev_io> watchers for
1846	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1967	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1847	provide just this functionality). Then, in the check watcher you check for	1968	provide just this functionality). Then, in the check watcher you check for
1848	any events that occured (by checking the pending status of all watchers	1969	any events that occurred (by checking the pending status of all watchers
1849	and stopping them) and call back into the library. The I/O and timer	1970	and stopping them) and call back into the library. The I/O and timer
1850	callbacks will never actually be called (but must be valid nevertheless,	1971	callbacks will never actually be called (but must be valid nevertheless,
1851	because you never know, you know?).	1972	because you never know, you know?).
1852		1973
1853	As another example, the Perl Coro module uses these hooks to integrate	1974	As another example, the Perl Coro module uses these hooks to integrate
…		…
1861		1982
1862	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1983	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
1863	priority, to ensure that they are being run before any other watchers	1984	priority, to ensure that they are being run before any other watchers
1864	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,	1985	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
1865	too) should not activate ("feed") events into libev. While libev fully	1986	too) should not activate ("feed") events into libev. While libev fully
1866	supports this, they will be called before other C<ev_check> watchers	1987	supports this, they might get executed before other C<ev_check> watchers
1867	did their job. As C<ev_check> watchers are often used to embed other	1988	did their job. As C<ev_check> watchers are often used to embed other
1868	(non-libev) event loops those other event loops might be in an unusable	1989	(non-libev) event loops those other event loops might be in an unusable
1869	state until their C<ev_check> watcher ran (always remind yourself to	1990	state until their C<ev_check> watcher ran (always remind yourself to
1870	coexist peacefully with others).	1991	coexist peacefully with others).
1871		1992
…		…
1886	=head3 Examples	2007	=head3 Examples
1887		2008
1888	There are a number of principal ways to embed other event loops or modules	2009	There are a number of principal ways to embed other event loops or modules
1889	into libev. Here are some ideas on how to include libadns into libev	2010	into libev. Here are some ideas on how to include libadns into libev
1890	(there is a Perl module named C<EV::ADNS> that does this, which you could	2011	(there is a Perl module named C<EV::ADNS> that does this, which you could
1891	use for an actually working example. Another Perl module named C<EV::Glib>	2012	use as a working example. Another Perl module named C<EV::Glib> embeds a
1892	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV	2013	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1893	into the Glib event loop).	2014	Glib event loop).
1894		2015
1895	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	2016	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1896	and in a check watcher, destroy them and call into libadns. What follows	2017	and in a check watcher, destroy them and call into libadns. What follows
1897	is pseudo-code only of course. This requires you to either use a low	2018	is pseudo-code only of course. This requires you to either use a low
1898	priority for the check watcher or use C<ev_clear_pending> explicitly, as	2019	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1899	the callbacks for the IO/timeout watchers might not have been called yet.	2020	the callbacks for the IO/timeout watchers might not have been called yet.
1900		2021
1901	static ev_io iow [nfd];	2022	static ev_io iow [nfd];
1902	static ev_timer tw;	2023	static ev_timer tw;
1903		2024
1904	static void	2025	static void
1905	io_cb (ev_loop *loop, ev_io *w, int revents)	2026	io_cb (ev_loop *loop, ev_io *w, int revents)
1906	{	2027	{
1907	}	2028	}
1908		2029
1909	// create io watchers for each fd and a timer before blocking	2030	// create io watchers for each fd and a timer before blocking
1910	static void	2031	static void
1911	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	2032	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1912	{	2033	{
1913	int timeout = 3600000;	2034	int timeout = 3600000;
1914	struct pollfd fds [nfd];	2035	struct pollfd fds [nfd];
1915	// actual code will need to loop here and realloc etc.	2036	// actual code will need to loop here and realloc etc.
1916	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	2037	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1917		2038
1918	/* the callback is illegal, but won't be called as we stop during check */	2039	/* the callback is illegal, but won't be called as we stop during check */
1919	ev_timer_init (&tw, 0, timeout * 1e-3);	2040	ev_timer_init (&tw, 0, timeout * 1e-3);
1920	ev_timer_start (loop, &tw);	2041	ev_timer_start (loop, &tw);
1921		2042
1922	// create one ev_io per pollfd	2043	// create one ev_io per pollfd
1923	for (int i = 0; i < nfd; ++i)	2044	for (int i = 0; i < nfd; ++i)
1924	{	2045	{
1925	ev_io_init (iow + i, io_cb, fds [i].fd,	2046	ev_io_init (iow + i, io_cb, fds [i].fd,
1926	((fds [i].events & POLLIN ? EV_READ : 0)	2047	((fds [i].events & POLLIN ? EV_READ : 0)
1927	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	2048	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1928		2049
1929	fds [i].revents = 0;	2050	fds [i].revents = 0;
1930	ev_io_start (loop, iow + i);	2051	ev_io_start (loop, iow + i);
1931	}	2052	}
1932	}	2053	}
1933		2054
1934	// stop all watchers after blocking	2055	// stop all watchers after blocking
1935	static void	2056	static void
1936	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	2057	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1937	{	2058	{
1938	ev_timer_stop (loop, &tw);	2059	ev_timer_stop (loop, &tw);
1939		2060
1940	for (int i = 0; i < nfd; ++i)	2061	for (int i = 0; i < nfd; ++i)
1941	{	2062	{
1942	// set the relevant poll flags	2063	// set the relevant poll flags
1943	// could also call adns_processreadable etc. here	2064	// could also call adns_processreadable etc. here
1944	struct pollfd *fd = fds + i;	2065	struct pollfd *fd = fds + i;
1945	int revents = ev_clear_pending (iow + i);	2066	int revents = ev_clear_pending (iow + i);
1946	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	2067	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1947	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	2068	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1948		2069
1949	// now stop the watcher	2070	// now stop the watcher
1950	ev_io_stop (loop, iow + i);	2071	ev_io_stop (loop, iow + i);
1951	}	2072	}
1952		2073
1953	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2074	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1954	}	2075	}
1955		2076
1956	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2077	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
1957	in the prepare watcher and would dispose of the check watcher.	2078	in the prepare watcher and would dispose of the check watcher.
1958		2079
1959	Method 3: If the module to be embedded supports explicit event	2080	Method 3: If the module to be embedded supports explicit event
1960	notification (adns does), you can also make use of the actual watcher	2081	notification (libadns does), you can also make use of the actual watcher
1961	callbacks, and only destroy/create the watchers in the prepare watcher.	2082	callbacks, and only destroy/create the watchers in the prepare watcher.
1962		2083
1963	static void	2084	static void
1964	timer_cb (EV_P_ ev_timer *w, int revents)	2085	timer_cb (EV_P_ ev_timer *w, int revents)
1965	{	2086	{
1966	adns_state ads = (adns_state)w->data;	2087	adns_state ads = (adns_state)w->data;
1967	update_now (EV_A);	2088	update_now (EV_A);
1968		2089
1969	adns_processtimeouts (ads, &tv_now);	2090	adns_processtimeouts (ads, &tv_now);
1970	}	2091	}
1971		2092
1972	static void	2093	static void
1973	io_cb (EV_P_ ev_io *w, int revents)	2094	io_cb (EV_P_ ev_io *w, int revents)
1974	{	2095	{
1975	adns_state ads = (adns_state)w->data;	2096	adns_state ads = (adns_state)w->data;
1976	update_now (EV_A);	2097	update_now (EV_A);
1977		2098
1978	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2099	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1979	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2100	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1980	}	2101	}
1981		2102
1982	// do not ever call adns_afterpoll	2103	// do not ever call adns_afterpoll
1983		2104
1984	Method 4: Do not use a prepare or check watcher because the module you	2105	Method 4: Do not use a prepare or check watcher because the module you
1985	want to embed is too inflexible to support it. Instead, youc na override	2106	want to embed is too inflexible to support it. Instead, you can override
1986	their poll function. The drawback with this solution is that the main	2107	their poll function. The drawback with this solution is that the main
1987	loop is now no longer controllable by EV. The C<Glib::EV> module does	2108	loop is now no longer controllable by EV. The C<Glib::EV> module does
1988	this.	2109	this.
1989		2110
1990	static gint	2111	static gint
1991	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2112	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1992	{	2113	{
1993	int got_events = 0;	2114	int got_events = 0;
1994		2115
1995	for (n = 0; n < nfds; ++n)	2116	for (n = 0; n < nfds; ++n)
1996	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2117	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1997		2118
1998	if (timeout >= 0)	2119	if (timeout >= 0)
1999	// create/start timer	2120	// create/start timer
2000		2121
2001	// poll	2122	// poll
2002	ev_loop (EV_A_ 0);	2123	ev_loop (EV_A_ 0);
2003		2124
2004	// stop timer again	2125	// stop timer again
2005	if (timeout >= 0)	2126	if (timeout >= 0)
2006	ev_timer_stop (EV_A_ &to);	2127	ev_timer_stop (EV_A_ &to);
2007		2128
2008	// stop io watchers again - their callbacks should have set	2129	// stop io watchers again - their callbacks should have set
2009	for (n = 0; n < nfds; ++n)	2130	for (n = 0; n < nfds; ++n)
2010	ev_io_stop (EV_A_ iow [n]);	2131	ev_io_stop (EV_A_ iow [n]);
2011		2132
2012	return got_events;	2133	return got_events;
2013	}	2134	}
2014		2135
2015		2136
2016	=head2 C<ev_embed> - when one backend isn't enough...	2137	=head2 C<ev_embed> - when one backend isn't enough...
2017		2138
2018	This is a rather advanced watcher type that lets you embed one event loop	2139	This is a rather advanced watcher type that lets you embed one event loop
…		…
2074		2195
2075	Configures the watcher to embed the given loop, which must be	2196	Configures the watcher to embed the given loop, which must be
2076	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be	2197	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
2077	invoked automatically, otherwise it is the responsibility of the callback	2198	invoked automatically, otherwise it is the responsibility of the callback
2078	to invoke it (it will continue to be called until the sweep has been done,	2199	to invoke it (it will continue to be called until the sweep has been done,
2079	if you do not want thta, you need to temporarily stop the embed watcher).	2200	if you do not want that, you need to temporarily stop the embed watcher).
2080		2201
2081	=item ev_embed_sweep (loop, ev_embed *)	2202	=item ev_embed_sweep (loop, ev_embed *)
2082		2203
2083	Make a single, non-blocking sweep over the embedded loop. This works	2204	Make a single, non-blocking sweep over the embedded loop. This works
2084	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2205	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2085	apropriate way for embedded loops.	2206	appropriate way for embedded loops.
2086		2207
2087	=item struct ev_loop *other [read-only]	2208	=item struct ev_loop *other [read-only]
2088		2209
2089	The embedded event loop.	2210	The embedded event loop.
2090		2211
…		…
2092		2213
2093	=head3 Examples	2214	=head3 Examples
2094		2215
2095	Example: Try to get an embeddable event loop and embed it into the default	2216	Example: Try to get an embeddable event loop and embed it into the default
2096	event loop. If that is not possible, use the default loop. The default	2217	event loop. If that is not possible, use the default loop. The default
2097	loop is stored in C<loop_hi>, while the mebeddable loop is stored in	2218	loop is stored in C<loop_hi>, while the embeddable loop is stored in
2098	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be	2219	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2099	used).	2220	used).
2100		2221
2101	struct ev_loop *loop_hi = ev_default_init (0);	2222	struct ev_loop *loop_hi = ev_default_init (0);
2102	struct ev_loop *loop_lo = 0;	2223	struct ev_loop *loop_lo = 0;
2103	struct ev_embed embed;	2224	struct ev_embed embed;
2104		2225
2105	// see if there is a chance of getting one that works	2226	// see if there is a chance of getting one that works
2106	// (remember that a flags value of 0 means autodetection)	2227	// (remember that a flags value of 0 means autodetection)
2107	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2228	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2108	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2229	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2109	: 0;	2230	: 0;
2110		2231
2111	// if we got one, then embed it, otherwise default to loop_hi	2232	// if we got one, then embed it, otherwise default to loop_hi
2112	if (loop_lo)	2233	if (loop_lo)
2113	{	2234	{
2114	ev_embed_init (&embed, 0, loop_lo);	2235	ev_embed_init (&embed, 0, loop_lo);
2115	ev_embed_start (loop_hi, &embed);	2236	ev_embed_start (loop_hi, &embed);
2116	}	2237	}
2117	else	2238	else
2118	loop_lo = loop_hi;	2239	loop_lo = loop_hi;
2119		2240
2120	Example: Check if kqueue is available but not recommended and create	2241	Example: Check if kqueue is available but not recommended and create
2121	a kqueue backend for use with sockets (which usually work with any	2242	a kqueue backend for use with sockets (which usually work with any
2122	kqueue implementation). Store the kqueue/socket-only event loop in	2243	kqueue implementation). Store the kqueue/socket-only event loop in
2123	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2244	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2124		2245
2125	struct ev_loop *loop = ev_default_init (0);	2246	struct ev_loop *loop = ev_default_init (0);
2126	struct ev_loop *loop_socket = 0;	2247	struct ev_loop *loop_socket = 0;
2127	struct ev_embed embed;	2248	struct ev_embed embed;
2128		2249
2129	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2250	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2130	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2251	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2131	{	2252	{
2132	ev_embed_init (&embed, 0, loop_socket);	2253	ev_embed_init (&embed, 0, loop_socket);
2133	ev_embed_start (loop, &embed);	2254	ev_embed_start (loop, &embed);
2134	}	2255	}
2135		2256
2136	if (!loop_socket)	2257	if (!loop_socket)
2137	loop_socket = loop;	2258	loop_socket = loop;
2138		2259
2139	// now use loop_socket for all sockets, and loop for everything else	2260	// now use loop_socket for all sockets, and loop for everything else
2140		2261
2141		2262
2142	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2263	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2143		2264
2144	Fork watchers are called when a C<fork ()> was detected (usually because	2265	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2197		2318
2198	=item queueing from a signal handler context	2319	=item queueing from a signal handler context
2199		2320
2200	To implement race-free queueing, you simply add to the queue in the signal	2321	To implement race-free queueing, you simply add to the queue in the signal
2201	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2322	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2202	some fictitiuous SIGUSR1 handler:	2323	some fictitious SIGUSR1 handler:
2203		2324
2204	static ev_async mysig;	2325	static ev_async mysig;
2205		2326
2206	static void	2327	static void
2207	sigusr1_handler (void)	2328	sigusr1_handler (void)
…		…
2281	=item ev_async_send (loop, ev_async *)	2402	=item ev_async_send (loop, ev_async *)
2282		2403
2283	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2404	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2284	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2405	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2285	C<ev_feed_event>, this call is safe to do in other threads, signal or	2406	C<ev_feed_event>, this call is safe to do in other threads, signal or
2286	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding	2407	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2287	section below on what exactly this means).	2408	section below on what exactly this means).
2288		2409
2289	This call incurs the overhead of a syscall only once per loop iteration,	2410	This call incurs the overhead of a system call only once per loop iteration,
2290	so while the overhead might be noticable, it doesn't apply to repeated	2411	so while the overhead might be noticeable, it doesn't apply to repeated
2291	calls to C<ev_async_send>.	2412	calls to C<ev_async_send>.
		2413
		2414	=item bool = ev_async_pending (ev_async *)
		2415
		2416	Returns a non-zero value when C<ev_async_send> has been called on the
		2417	watcher but the event has not yet been processed (or even noted) by the
		2418	event loop.
		2419
		2420	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
		2421	the loop iterates next and checks for the watcher to have become active,
		2422	it will reset the flag again. C<ev_async_pending> can be used to very
		2423	quickly check whether invoking the loop might be a good idea.
		2424
		2425	Not that this does I<not> check whether the watcher itself is pending, only
		2426	whether it has been requested to make this watcher pending.
2292		2427
2293	=back	2428	=back
2294		2429
2295		2430
2296	=head1 OTHER FUNCTIONS	2431	=head1 OTHER FUNCTIONS
…		…
2307	or timeout without having to allocate/configure/start/stop/free one or	2442	or timeout without having to allocate/configure/start/stop/free one or
2308	more watchers yourself.	2443	more watchers yourself.
2309		2444
2310	If C<fd> is less than 0, then no I/O watcher will be started and events	2445	If C<fd> is less than 0, then no I/O watcher will be started and events
2311	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2446	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2312	C<events> set will be craeted and started.	2447	C<events> set will be created and started.
2313		2448
2314	If C<timeout> is less than 0, then no timeout watcher will be	2449	If C<timeout> is less than 0, then no timeout watcher will be
2315	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2450	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2316	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2451	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2317	dubious value.	2452	dubious value.
…		…
2319	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2454	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2320	passed an C<revents> set like normal event callbacks (a combination of	2455	passed an C<revents> set like normal event callbacks (a combination of
2321	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2456	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2322	value passed to C<ev_once>:	2457	value passed to C<ev_once>:
2323		2458
2324	static void stdin_ready (int revents, void *arg)	2459	static void stdin_ready (int revents, void *arg)
2325	{	2460	{
2326	if (revents & EV_TIMEOUT)	2461	if (revents & EV_TIMEOUT)
2327	/* doh, nothing entered */;	2462	/* doh, nothing entered */;
2328	else if (revents & EV_READ)	2463	else if (revents & EV_READ)
2329	/* stdin might have data for us, joy! */;	2464	/* stdin might have data for us, joy! */;
2330	}	2465	}
2331		2466
2332	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2467	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2333		2468
2334	=item ev_feed_event (ev_loop *, watcher *, int revents)	2469	=item ev_feed_event (ev_loop *, watcher *, int revents)
2335		2470
2336	Feeds the given event set into the event loop, as if the specified event	2471	Feeds the given event set into the event loop, as if the specified event
2337	had happened for the specified watcher (which must be a pointer to an	2472	had happened for the specified watcher (which must be a pointer to an
…		…
2342	Feed an event on the given fd, as if a file descriptor backend detected	2477	Feed an event on the given fd, as if a file descriptor backend detected
2343	the given events it.	2478	the given events it.
2344		2479
2345	=item ev_feed_signal_event (ev_loop *loop, int signum)	2480	=item ev_feed_signal_event (ev_loop *loop, int signum)
2346		2481
2347	Feed an event as if the given signal occured (C<loop> must be the default	2482	Feed an event as if the given signal occurred (C<loop> must be the default
2348	loop!).	2483	loop!).
2349		2484
2350	=back	2485	=back
2351		2486
2352		2487
…		…
2368		2503
2369	=item * Priorities are not currently supported. Initialising priorities	2504	=item * Priorities are not currently supported. Initialising priorities
2370	will fail and all watchers will have the same priority, even though there	2505	will fail and all watchers will have the same priority, even though there
2371	is an ev_pri field.	2506	is an ev_pri field.
2372		2507
		2508	=item * In libevent, the last base created gets the signals, in libev, the
		2509	first base created (== the default loop) gets the signals.
		2510
2373	=item * Other members are not supported.	2511	=item * Other members are not supported.
2374		2512
2375	=item * The libev emulation is I<not> ABI compatible to libevent, you need	2513	=item * The libev emulation is I<not> ABI compatible to libevent, you need
2376	to use the libev header file and library.	2514	to use the libev header file and library.
2377		2515
2378	=back	2516	=back
2379		2517
2380	=head1 C++ SUPPORT	2518	=head1 C++ SUPPORT
2381		2519
2382	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2520	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2383	you to use some convinience methods to start/stop watchers and also change	2521	you to use some convenience methods to start/stop watchers and also change
2384	the callback model to a model using method callbacks on objects.	2522	the callback model to a model using method callbacks on objects.
2385		2523
2386	To use it,	2524	To use it,
2387		2525
2388	#include <ev++.h>	2526	#include <ev++.h>
2389		2527
2390	This automatically includes F<ev.h> and puts all of its definitions (many	2528	This automatically includes F<ev.h> and puts all of its definitions (many
2391	of them macros) into the global namespace. All C++ specific things are	2529	of them macros) into the global namespace. All C++ specific things are
2392	put into the C<ev> namespace. It should support all the same embedding	2530	put into the C<ev> namespace. It should support all the same embedding
2393	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2531	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2460	your compiler is good :), then the method will be fully inlined into the	2598	your compiler is good :), then the method will be fully inlined into the
2461	thunking function, making it as fast as a direct C callback.	2599	thunking function, making it as fast as a direct C callback.
2462		2600
2463	Example: simple class declaration and watcher initialisation	2601	Example: simple class declaration and watcher initialisation
2464		2602
2465	struct myclass	2603	struct myclass
2466	{	2604	{
2467	void io_cb (ev::io &w, int revents) { }	2605	void io_cb (ev::io &w, int revents) { }
2468	}	2606	}
2469		2607
2470	myclass obj;	2608	myclass obj;
2471	ev::io iow;	2609	ev::io iow;
2472	iow.set <myclass, &myclass::io_cb> (&obj);	2610	iow.set <myclass, &myclass::io_cb> (&obj);
2473		2611
2474	=item w->set<function> (void *data = 0)	2612	=item w->set<function> (void *data = 0)
2475		2613
2476	Also sets a callback, but uses a static method or plain function as	2614	Also sets a callback, but uses a static method or plain function as
2477	callback. The optional C<data> argument will be stored in the watcher's	2615	callback. The optional C<data> argument will be stored in the watcher's
…		…
2481		2619
2482	See the method-C<set> above for more details.	2620	See the method-C<set> above for more details.
2483		2621
2484	Example:	2622	Example:
2485		2623
2486	static void io_cb (ev::io &w, int revents) { }	2624	static void io_cb (ev::io &w, int revents) { }
2487	iow.set <io_cb> ();	2625	iow.set <io_cb> ();
2488		2626
2489	=item w->set (struct ev_loop *)	2627	=item w->set (struct ev_loop *)
2490		2628
2491	Associates a different C<struct ev_loop> with this watcher. You can only	2629	Associates a different C<struct ev_loop> with this watcher. You can only
2492	do this when the watcher is inactive (and not pending either).	2630	do this when the watcher is inactive (and not pending either).
2493		2631
2494	=item w->set ([args])	2632	=item w->set ([arguments])
2495		2633
2496	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2634	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2497	called at least once. Unlike the C counterpart, an active watcher gets	2635	called at least once. Unlike the C counterpart, an active watcher gets
2498	automatically stopped and restarted when reconfiguring it with this	2636	automatically stopped and restarted when reconfiguring it with this
2499	method.	2637	method.
2500		2638
2501	=item w->start ()	2639	=item w->start ()
…		…
2525	=back	2663	=back
2526		2664
2527	Example: Define a class with an IO and idle watcher, start one of them in	2665	Example: Define a class with an IO and idle watcher, start one of them in
2528	the constructor.	2666	the constructor.
2529		2667
2530	class myclass	2668	class myclass
2531	{	2669	{
2532	ev::io io; void io_cb (ev::io &w, int revents);	2670	ev::io io; void io_cb (ev::io &w, int revents);
2533	ev:idle idle void idle_cb (ev::idle &w, int revents);	2671	ev:idle idle void idle_cb (ev::idle &w, int revents);
2534		2672
2535	myclass (int fd)	2673	myclass (int fd)
2536	{	2674	{
2537	io .set <myclass, &myclass::io_cb > (this);	2675	io .set <myclass, &myclass::io_cb > (this);
2538	idle.set <myclass, &myclass::idle_cb> (this);	2676	idle.set <myclass, &myclass::idle_cb> (this);
2539		2677
2540	io.start (fd, ev::READ);	2678	io.start (fd, ev::READ);
2541	}	2679	}
2542	};	2680	};
2543		2681
2544		2682
2545	=head1 OTHER LANGUAGE BINDINGS	2683	=head1 OTHER LANGUAGE BINDINGS
2546		2684
2547	Libev does not offer other language bindings itself, but bindings for a	2685	Libev does not offer other language bindings itself, but bindings for a
2548	numbe rof languages exist in the form of third-party packages. If you know	2686	number of languages exist in the form of third-party packages. If you know
2549	any interesting language binding in addition to the ones listed here, drop	2687	any interesting language binding in addition to the ones listed here, drop
2550	me a note.	2688	me a note.
2551		2689
2552	=over 4	2690	=over 4
2553		2691
…		…
2557	libev. EV is developed together with libev. Apart from the EV core module,	2695	libev. EV is developed together with libev. Apart from the EV core module,
2558	there are additional modules that implement libev-compatible interfaces	2696	there are additional modules that implement libev-compatible interfaces
2559	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the	2697	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
2560	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).	2698	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2561		2699
2562	It can be found and installed via CPAN, its homepage is found at	2700	It can be found and installed via CPAN, its homepage is at
2563	L<http://software.schmorp.de/pkg/EV>.	2701	L<http://software.schmorp.de/pkg/EV>.
2564		2702
		2703	=item Python
		2704
		2705	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2706	seems to be quite complete and well-documented. Note, however, that the
		2707	patch they require for libev is outright dangerous as it breaks the ABI
		2708	for everybody else, and therefore, should never be applied in an installed
		2709	libev (if python requires an incompatible ABI then it needs to embed
		2710	libev).
		2711
2565	=item Ruby	2712	=item Ruby
2566		2713
2567	Tony Arcieri has written a ruby extension that offers access to a subset	2714	Tony Arcieri has written a ruby extension that offers access to a subset
2568	of the libev API and adds filehandle abstractions, asynchronous DNS and	2715	of the libev API and adds file handle abstractions, asynchronous DNS and
2569	more on top of it. It can be found via gem servers. Its homepage is at	2716	more on top of it. It can be found via gem servers. Its homepage is at
2570	L<http://rev.rubyforge.org/>.	2717	L<http://rev.rubyforge.org/>.
2571		2718
2572	=item D	2719	=item D
2573		2720
2574	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	2721	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
2575	be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.	2722	be found at L<http://proj.llucax.com.ar/wiki/evd>.
2576		2723
2577	=back	2724	=back
2578		2725
2579		2726
2580	=head1 MACRO MAGIC	2727	=head1 MACRO MAGIC
2581		2728
2582	Libev can be compiled with a variety of options, the most fundamantal	2729	Libev can be compiled with a variety of options, the most fundamental
2583	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2730	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2584	functions and callbacks have an initial C<struct ev_loop *> argument.	2731	functions and callbacks have an initial C<struct ev_loop *> argument.
2585		2732
2586	To make it easier to write programs that cope with either variant, the	2733	To make it easier to write programs that cope with either variant, the
2587	following macros are defined:	2734	following macros are defined:
…		…
2592		2739
2593	This provides the loop I<argument> for functions, if one is required ("ev	2740	This provides the loop I<argument> for functions, if one is required ("ev
2594	loop argument"). The C<EV_A> form is used when this is the sole argument,	2741	loop argument"). The C<EV_A> form is used when this is the sole argument,
2595	C<EV_A_> is used when other arguments are following. Example:	2742	C<EV_A_> is used when other arguments are following. Example:
2596		2743
2597	ev_unref (EV_A);	2744	ev_unref (EV_A);
2598	ev_timer_add (EV_A_ watcher);	2745	ev_timer_add (EV_A_ watcher);
2599	ev_loop (EV_A_ 0);	2746	ev_loop (EV_A_ 0);
2600		2747
2601	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2748	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2602	which is often provided by the following macro.	2749	which is often provided by the following macro.
2603		2750
2604	=item C<EV_P>, C<EV_P_>	2751	=item C<EV_P>, C<EV_P_>
2605		2752
2606	This provides the loop I<parameter> for functions, if one is required ("ev	2753	This provides the loop I<parameter> for functions, if one is required ("ev
2607	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2754	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2608	C<EV_P_> is used when other parameters are following. Example:	2755	C<EV_P_> is used when other parameters are following. Example:
2609		2756
2610	// this is how ev_unref is being declared	2757	// this is how ev_unref is being declared
2611	static void ev_unref (EV_P);	2758	static void ev_unref (EV_P);
2612		2759
2613	// this is how you can declare your typical callback	2760	// this is how you can declare your typical callback
2614	static void cb (EV_P_ ev_timer *w, int revents)	2761	static void cb (EV_P_ ev_timer *w, int revents)
2615		2762
2616	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2763	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2617	suitable for use with C<EV_A>.	2764	suitable for use with C<EV_A>.
2618		2765
2619	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2766	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
2620		2767
2621	Similar to the other two macros, this gives you the value of the default	2768	Similar to the other two macros, this gives you the value of the default
2622	loop, if multiple loops are supported ("ev loop default").	2769	loop, if multiple loops are supported ("ev loop default").
		2770
		2771	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
		2772
		2773	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
		2774	default loop has been initialised (C<UC> == unchecked). Their behaviour
		2775	is undefined when the default loop has not been initialised by a previous
		2776	execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
		2777
		2778	It is often prudent to use C<EV_DEFAULT> when initialising the first
		2779	watcher in a function but use C<EV_DEFAULT_UC> afterwards.
2623		2780
2624	=back	2781	=back
2625		2782
2626	Example: Declare and initialise a check watcher, utilising the above	2783	Example: Declare and initialise a check watcher, utilising the above
2627	macros so it will work regardless of whether multiple loops are supported	2784	macros so it will work regardless of whether multiple loops are supported
2628	or not.	2785	or not.
2629		2786
2630	static void	2787	static void
2631	check_cb (EV_P_ ev_timer *w, int revents)	2788	check_cb (EV_P_ ev_timer *w, int revents)
2632	{	2789	{
2633	ev_check_stop (EV_A_ w);	2790	ev_check_stop (EV_A_ w);
2634	}	2791	}
2635		2792
2636	ev_check check;	2793	ev_check check;
2637	ev_check_init (&check, check_cb);	2794	ev_check_init (&check, check_cb);
2638	ev_check_start (EV_DEFAULT_ &check);	2795	ev_check_start (EV_DEFAULT_ &check);
2639	ev_loop (EV_DEFAULT_ 0);	2796	ev_loop (EV_DEFAULT_ 0);
2640		2797
2641	=head1 EMBEDDING	2798	=head1 EMBEDDING
2642		2799
2643	Libev can (and often is) directly embedded into host	2800	Libev can (and often is) directly embedded into host
2644	applications. Examples of applications that embed it include the Deliantra	2801	applications. Examples of applications that embed it include the Deliantra
…		…
2651	libev somewhere in your source tree).	2808	libev somewhere in your source tree).
2652		2809
2653	=head2 FILESETS	2810	=head2 FILESETS
2654		2811
2655	Depending on what features you need you need to include one or more sets of files	2812	Depending on what features you need you need to include one or more sets of files
2656	in your app.	2813	in your application.
2657		2814
2658	=head3 CORE EVENT LOOP	2815	=head3 CORE EVENT LOOP
2659		2816
2660	To include only the libev core (all the C<ev_*> functions), with manual	2817	To include only the libev core (all the C<ev_*> functions), with manual
2661	configuration (no autoconf):	2818	configuration (no autoconf):
2662		2819
2663	#define EV_STANDALONE 1	2820	#define EV_STANDALONE 1
2664	#include "ev.c"	2821	#include "ev.c"
2665		2822
2666	This will automatically include F<ev.h>, too, and should be done in a	2823	This will automatically include F<ev.h>, too, and should be done in a
2667	single C source file only to provide the function implementations. To use	2824	single C source file only to provide the function implementations. To use
2668	it, do the same for F<ev.h> in all files wishing to use this API (best	2825	it, do the same for F<ev.h> in all files wishing to use this API (best
2669	done by writing a wrapper around F<ev.h> that you can include instead and	2826	done by writing a wrapper around F<ev.h> that you can include instead and
2670	where you can put other configuration options):	2827	where you can put other configuration options):
2671		2828
2672	#define EV_STANDALONE 1	2829	#define EV_STANDALONE 1
2673	#include "ev.h"	2830	#include "ev.h"
2674		2831
2675	Both header files and implementation files can be compiled with a C++	2832	Both header files and implementation files can be compiled with a C++
2676	compiler (at least, thats a stated goal, and breakage will be treated	2833	compiler (at least, thats a stated goal, and breakage will be treated
2677	as a bug).	2834	as a bug).
2678		2835
2679	You need the following files in your source tree, or in a directory	2836	You need the following files in your source tree, or in a directory
2680	in your include path (e.g. in libev/ when using -Ilibev):	2837	in your include path (e.g. in libev/ when using -Ilibev):
2681		2838
2682	ev.h	2839	ev.h
2683	ev.c	2840	ev.c
2684	ev_vars.h	2841	ev_vars.h
2685	ev_wrap.h	2842	ev_wrap.h
2686		2843
2687	ev_win32.c required on win32 platforms only	2844	ev_win32.c required on win32 platforms only
2688		2845
2689	ev_select.c only when select backend is enabled (which is enabled by default)	2846	ev_select.c only when select backend is enabled (which is enabled by default)
2690	ev_poll.c only when poll backend is enabled (disabled by default)	2847	ev_poll.c only when poll backend is enabled (disabled by default)
2691	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2848	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2692	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2849	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2693	ev_port.c only when the solaris port backend is enabled (disabled by default)	2850	ev_port.c only when the solaris port backend is enabled (disabled by default)
2694		2851
2695	F<ev.c> includes the backend files directly when enabled, so you only need	2852	F<ev.c> includes the backend files directly when enabled, so you only need
2696	to compile this single file.	2853	to compile this single file.
2697		2854
2698	=head3 LIBEVENT COMPATIBILITY API	2855	=head3 LIBEVENT COMPATIBILITY API
2699		2856
2700	To include the libevent compatibility API, also include:	2857	To include the libevent compatibility API, also include:
2701		2858
2702	#include "event.c"	2859	#include "event.c"
2703		2860
2704	in the file including F<ev.c>, and:	2861	in the file including F<ev.c>, and:
2705		2862
2706	#include "event.h"	2863	#include "event.h"
2707		2864
2708	in the files that want to use the libevent API. This also includes F<ev.h>.	2865	in the files that want to use the libevent API. This also includes F<ev.h>.
2709		2866
2710	You need the following additional files for this:	2867	You need the following additional files for this:
2711		2868
2712	event.h	2869	event.h
2713	event.c	2870	event.c
2714		2871
2715	=head3 AUTOCONF SUPPORT	2872	=head3 AUTOCONF SUPPORT
2716		2873
2717	Instead of using C<EV_STANDALONE=1> and providing your config in	2874	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2718	whatever way you want, you can also C<m4_include([libev.m4])> in your	2875	whatever way you want, you can also C<m4_include([libev.m4])> in your
2719	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2876	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2720	include F<config.h> and configure itself accordingly.	2877	include F<config.h> and configure itself accordingly.
2721		2878
2722	For this of course you need the m4 file:	2879	For this of course you need the m4 file:
2723		2880
2724	libev.m4	2881	libev.m4
2725		2882
2726	=head2 PREPROCESSOR SYMBOLS/MACROS	2883	=head2 PREPROCESSOR SYMBOLS/MACROS
2727		2884
2728	Libev can be configured via a variety of preprocessor symbols you have to define	2885	Libev can be configured via a variety of preprocessor symbols you have to
2729	before including any of its files. The default is not to build for multiplicity	2886	define before including any of its files. The default in the absence of
2730	and only include the select backend.	2887	autoconf is noted for every option.
2731		2888
2732	=over 4	2889	=over 4
2733		2890
2734	=item EV_STANDALONE	2891	=item EV_STANDALONE
2735		2892
…		…
2740	F<event.h> that are not directly supported by the libev core alone.	2897	F<event.h> that are not directly supported by the libev core alone.
2741		2898
2742	=item EV_USE_MONOTONIC	2899	=item EV_USE_MONOTONIC
2743		2900
2744	If defined to be C<1>, libev will try to detect the availability of the	2901	If defined to be C<1>, libev will try to detect the availability of the
2745	monotonic clock option at both compiletime and runtime. Otherwise no use	2902	monotonic clock option at both compile time and runtime. Otherwise no use
2746	of the monotonic clock option will be attempted. If you enable this, you	2903	of the monotonic clock option will be attempted. If you enable this, you
2747	usually have to link against librt or something similar. Enabling it when	2904	usually have to link against librt or something similar. Enabling it when
2748	the functionality isn't available is safe, though, although you have	2905	the functionality isn't available is safe, though, although you have
2749	to make sure you link against any libraries where the C<clock_gettime>	2906	to make sure you link against any libraries where the C<clock_gettime>
2750	function is hiding in (often F<-lrt>).	2907	function is hiding in (often F<-lrt>).
2751		2908
2752	=item EV_USE_REALTIME	2909	=item EV_USE_REALTIME
2753		2910
2754	If defined to be C<1>, libev will try to detect the availability of the	2911	If defined to be C<1>, libev will try to detect the availability of the
2755	realtime clock option at compiletime (and assume its availability at	2912	real-time clock option at compile time (and assume its availability at
2756	runtime if successful). Otherwise no use of the realtime clock option will	2913	runtime if successful). Otherwise no use of the real-time clock option will
2757	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2914	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2758	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2915	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2759	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2916	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2760		2917
2761	=item EV_USE_NANOSLEEP	2918	=item EV_USE_NANOSLEEP
2762		2919
2763	If defined to be C<1>, libev will assume that C<nanosleep ()> is available	2920	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
2764	and will use it for delays. Otherwise it will use C<select ()>.	2921	and will use it for delays. Otherwise it will use C<select ()>.
2765		2922
		2923	=item EV_USE_EVENTFD
		2924
		2925	If defined to be C<1>, then libev will assume that C<eventfd ()> is
		2926	available and will probe for kernel support at runtime. This will improve
		2927	C<ev_signal> and C<ev_async> performance and reduce resource consumption.
		2928	If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
		2929	2.7 or newer, otherwise disabled.
		2930
2766	=item EV_USE_SELECT	2931	=item EV_USE_SELECT
2767		2932
2768	If undefined or defined to be C<1>, libev will compile in support for the	2933	If undefined or defined to be C<1>, libev will compile in support for the
2769	C<select>(2) backend. No attempt at autodetection will be done: if no	2934	C<select>(2) backend. No attempt at auto-detection will be done: if no
2770	other method takes over, select will be it. Otherwise the select backend	2935	other method takes over, select will be it. Otherwise the select backend
2771	will not be compiled in.	2936	will not be compiled in.
2772		2937
2773	=item EV_SELECT_USE_FD_SET	2938	=item EV_SELECT_USE_FD_SET
2774		2939
2775	If defined to C<1>, then the select backend will use the system C<fd_set>	2940	If defined to C<1>, then the select backend will use the system C<fd_set>
2776	structure. This is useful if libev doesn't compile due to a missing	2941	structure. This is useful if libev doesn't compile due to a missing
2777	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	2942	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
2778	exotic systems. This usually limits the range of file descriptors to some	2943	exotic systems. This usually limits the range of file descriptors to some
2779	low limit such as 1024 or might have other limitations (winsocket only	2944	low limit such as 1024 or might have other limitations (winsocket only
2780	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	2945	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2781	influence the size of the C<fd_set> used.	2946	influence the size of the C<fd_set> used.
2782		2947
…		…
2806		2971
2807	=item EV_USE_EPOLL	2972	=item EV_USE_EPOLL
2808		2973
2809	If defined to be C<1>, libev will compile in support for the Linux	2974	If defined to be C<1>, libev will compile in support for the Linux
2810	C<epoll>(7) backend. Its availability will be detected at runtime,	2975	C<epoll>(7) backend. Its availability will be detected at runtime,
2811	otherwise another method will be used as fallback. This is the	2976	otherwise another method will be used as fallback. This is the preferred
2812	preferred backend for GNU/Linux systems.	2977	backend for GNU/Linux systems. If undefined, it will be enabled if the
		2978	headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2813		2979
2814	=item EV_USE_KQUEUE	2980	=item EV_USE_KQUEUE
2815		2981
2816	If defined to be C<1>, libev will compile in support for the BSD style	2982	If defined to be C<1>, libev will compile in support for the BSD style
2817	C<kqueue>(2) backend. Its actual availability will be detected at runtime,	2983	C<kqueue>(2) backend. Its actual availability will be detected at runtime,
…		…
2830	otherwise another method will be used as fallback. This is the preferred	2996	otherwise another method will be used as fallback. This is the preferred
2831	backend for Solaris 10 systems.	2997	backend for Solaris 10 systems.
2832		2998
2833	=item EV_USE_DEVPOLL	2999	=item EV_USE_DEVPOLL
2834		3000
2835	reserved for future expansion, works like the USE symbols above.	3001	Reserved for future expansion, works like the USE symbols above.
2836		3002
2837	=item EV_USE_INOTIFY	3003	=item EV_USE_INOTIFY
2838		3004
2839	If defined to be C<1>, libev will compile in support for the Linux inotify	3005	If defined to be C<1>, libev will compile in support for the Linux inotify
2840	interface to speed up C<ev_stat> watchers. Its actual availability will	3006	interface to speed up C<ev_stat> watchers. Its actual availability will
2841	be detected at runtime.	3007	be detected at runtime. If undefined, it will be enabled if the headers
		3008	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2842		3009
2843	=item EV_ATOMIC_T	3010	=item EV_ATOMIC_T
2844		3011
2845	Libev requires an integer type (suitable for storing C<0> or C<1>) whose	3012	Libev requires an integer type (suitable for storing C<0> or C<1>) whose
2846	access is atomic with respect to other threads or signal contexts. No such	3013	access is atomic with respect to other threads or signal contexts. No such
2847	type is easily found in the C language, so you can provide your own type	3014	type is easily found in the C language, so you can provide your own type
2848	that you know is safe for your purposes. It is used both for signal handler "locking"	3015	that you know is safe for your purposes. It is used both for signal handler "locking"
2849	as well as for signal and thread safety in C<ev_async> watchers.	3016	as well as for signal and thread safety in C<ev_async> watchers.
2850		3017
2851	In the absense of this define, libev will use C<sig_atomic_t volatile>	3018	In the absence of this define, libev will use C<sig_atomic_t volatile>
2852	(from F<signal.h>), which is usually good enough on most platforms.	3019	(from F<signal.h>), which is usually good enough on most platforms.
2853		3020
2854	=item EV_H	3021	=item EV_H
2855		3022
2856	The name of the F<ev.h> header file used to include it. The default if	3023	The name of the F<ev.h> header file used to include it. The default if
…		…
2895	When doing priority-based operations, libev usually has to linearly search	3062	When doing priority-based operations, libev usually has to linearly search
2896	all the priorities, so having many of them (hundreds) uses a lot of space	3063	all the priorities, so having many of them (hundreds) uses a lot of space
2897	and time, so using the defaults of five priorities (-2 .. +2) is usually	3064	and time, so using the defaults of five priorities (-2 .. +2) is usually
2898	fine.	3065	fine.
2899		3066
2900	If your embedding app does not need any priorities, defining these both to	3067	If your embedding application does not need any priorities, defining these both to
2901	C<0> will save some memory and cpu.	3068	C<0> will save some memory and CPU.
2902		3069
2903	=item EV_PERIODIC_ENABLE	3070	=item EV_PERIODIC_ENABLE
2904		3071
2905	If undefined or defined to be C<1>, then periodic timers are supported. If	3072	If undefined or defined to be C<1>, then periodic timers are supported. If
2906	defined to be C<0>, then they are not. Disabling them saves a few kB of	3073	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
2933	defined to be C<0>, then they are not.	3100	defined to be C<0>, then they are not.
2934		3101
2935	=item EV_MINIMAL	3102	=item EV_MINIMAL
2936		3103
2937	If you need to shave off some kilobytes of code at the expense of some	3104	If you need to shave off some kilobytes of code at the expense of some
2938	speed, define this symbol to C<1>. Currently only used for gcc to override	3105	speed, define this symbol to C<1>. Currently this is used to override some
2939	some inlining decisions, saves roughly 30% codesize of amd64.	3106	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3107	much smaller 2-heap for timer management over the default 4-heap.
2940		3108
2941	=item EV_PID_HASHSIZE	3109	=item EV_PID_HASHSIZE
2942		3110
2943	C<ev_child> watchers use a small hash table to distribute workload by	3111	C<ev_child> watchers use a small hash table to distribute workload by
2944	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3112	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
…		…
2951	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	3119	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2952	usually more than enough. If you need to manage thousands of C<ev_stat>	3120	usually more than enough. If you need to manage thousands of C<ev_stat>
2953	watchers you might want to increase this value (I<must> be a power of	3121	watchers you might want to increase this value (I<must> be a power of
2954	two).	3122	two).
2955		3123
		3124	=item EV_USE_4HEAP
		3125
		3126	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3127	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3128	to C<1>. The 4-heap uses more complicated (longer) code but has
		3129	noticeably faster performance with many (thousands) of watchers.
		3130
		3131	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3132	(disabled).
		3133
		3134	=item EV_HEAP_CACHE_AT
		3135
		3136	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3137	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3138	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3139	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3140	but avoids random read accesses on heap changes. This improves performance
		3141	noticeably with with many (hundreds) of watchers.
		3142
		3143	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3144	(disabled).
		3145
		3146	=item EV_VERIFY
		3147
		3148	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3149	be done: If set to C<0>, no internal verification code will be compiled
		3150	in. If set to C<1>, then verification code will be compiled in, but not
		3151	called. If set to C<2>, then the internal verification code will be
		3152	called once per loop, which can slow down libev. If set to C<3>, then the
		3153	verification code will be called very frequently, which will slow down
		3154	libev considerably.
		3155
		3156	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3157	C<0.>
		3158
2956	=item EV_COMMON	3159	=item EV_COMMON
2957		3160
2958	By default, all watchers have a C<void *data> member. By redefining	3161	By default, all watchers have a C<void *data> member. By redefining
2959	this macro to a something else you can include more and other types of	3162	this macro to a something else you can include more and other types of
2960	members. You have to define it each time you include one of the files,	3163	members. You have to define it each time you include one of the files,
2961	though, and it must be identical each time.	3164	though, and it must be identical each time.
2962		3165
2963	For example, the perl EV module uses something like this:	3166	For example, the perl EV module uses something like this:
2964		3167
2965	#define EV_COMMON \	3168	#define EV_COMMON \
2966	SV *self; /* contains this struct */ \	3169	SV *self; /* contains this struct */ \
2967	SV *cb_sv, *fh /* note no trailing ";" */	3170	SV *cb_sv, *fh /* note no trailing ";" */
2968		3171
2969	=item EV_CB_DECLARE (type)	3172	=item EV_CB_DECLARE (type)
2970		3173
2971	=item EV_CB_INVOKE (watcher, revents)	3174	=item EV_CB_INVOKE (watcher, revents)
2972		3175
…		…
2979	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3182	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2980	method calls instead of plain function calls in C++.	3183	method calls instead of plain function calls in C++.
2981		3184
2982	=head2 EXPORTED API SYMBOLS	3185	=head2 EXPORTED API SYMBOLS
2983		3186
2984	If you need to re-export the API (e.g. via a dll) and you need a list of	3187	If you need to re-export the API (e.g. via a DLL) and you need a list of
2985	exported symbols, you can use the provided F<Symbol.*> files which list	3188	exported symbols, you can use the provided F<Symbol.*> files which list
2986	all public symbols, one per line:	3189	all public symbols, one per line:
2987		3190
2988	Symbols.ev for libev proper	3191	Symbols.ev for libev proper
2989	Symbols.event for the libevent emulation	3192	Symbols.event for the libevent emulation
2990		3193
2991	This can also be used to rename all public symbols to avoid clashes with	3194	This can also be used to rename all public symbols to avoid clashes with
2992	multiple versions of libev linked together (which is obviously bad in	3195	multiple versions of libev linked together (which is obviously bad in
2993	itself, but sometimes it is inconvinient to avoid this).	3196	itself, but sometimes it is inconvenient to avoid this).
2994		3197
2995	A sed command like this will create wrapper C<#define>'s that you need to	3198	A sed command like this will create wrapper C<#define>'s that you need to
2996	include before including F<ev.h>:	3199	include before including F<ev.h>:
2997		3200
2998	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3201	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3015	file.	3218	file.
3016		3219
3017	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3220	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3018	that everybody includes and which overrides some configure choices:	3221	that everybody includes and which overrides some configure choices:
3019		3222
3020	#define EV_MINIMAL 1	3223	#define EV_MINIMAL 1
3021	#define EV_USE_POLL 0	3224	#define EV_USE_POLL 0
3022	#define EV_MULTIPLICITY 0	3225	#define EV_MULTIPLICITY 0
3023	#define EV_PERIODIC_ENABLE 0	3226	#define EV_PERIODIC_ENABLE 0
3024	#define EV_STAT_ENABLE 0	3227	#define EV_STAT_ENABLE 0
3025	#define EV_FORK_ENABLE 0	3228	#define EV_FORK_ENABLE 0
3026	#define EV_CONFIG_H <config.h>	3229	#define EV_CONFIG_H <config.h>
3027	#define EV_MINPRI 0	3230	#define EV_MINPRI 0
3028	#define EV_MAXPRI 0	3231	#define EV_MAXPRI 0
3029		3232
3030	#include "ev++.h"	3233	#include "ev++.h"
3031		3234
3032	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3235	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3033		3236
3034	#include "ev_cpp.h"	3237	#include "ev_cpp.h"
3035	#include "ev.c"	3238	#include "ev.c"
		3239
		3240
		3241	=head1 THREADS AND COROUTINES
		3242
		3243	=head2 THREADS
		3244
		3245	Libev itself is completely thread-safe, but it uses no locking. This
		3246	means that you can use as many loops as you want in parallel, as long as
		3247	only one thread ever calls into one libev function with the same loop
		3248	parameter.
		3249
		3250	Or put differently: calls with different loop parameters can be done in
		3251	parallel from multiple threads, calls with the same loop parameter must be
		3252	done serially (but can be done from different threads, as long as only one
		3253	thread ever is inside a call at any point in time, e.g. by using a mutex
		3254	per loop).
		3255
		3256	If you want to know which design (one loop, locking, or multiple loops
		3257	without or something else still) is best for your problem, then I cannot
		3258	help you. I can give some generic advice however:
		3259
		3260	=over 4
		3261
		3262	=item * most applications have a main thread: use the default libev loop
		3263	in that thread, or create a separate thread running only the default loop.
		3264
		3265	This helps integrating other libraries or software modules that use libev
		3266	themselves and don't care/know about threading.
		3267
		3268	=item * one loop per thread is usually a good model.
		3269
		3270	Doing this is almost never wrong, sometimes a better-performance model
		3271	exists, but it is always a good start.
		3272
		3273	=item * other models exist, such as the leader/follower pattern, where one
		3274	loop is handed through multiple threads in a kind of round-robin fashion.
		3275
		3276	Choosing a model is hard - look around, learn, know that usually you can do
		3277	better than you currently do :-)
		3278
		3279	=item * often you need to talk to some other thread which blocks in the
		3280	event loop - C<ev_async> watchers can be used to wake them up from other
		3281	threads safely (or from signal contexts...).
		3282
		3283	=back
		3284
		3285	=head2 COROUTINES
		3286
		3287	Libev is much more accommodating to coroutines ("cooperative threads"):
		3288	libev fully supports nesting calls to it's functions from different
		3289	coroutines (e.g. you can call C<ev_loop> on the same loop from two
		3290	different coroutines and switch freely between both coroutines running the
		3291	loop, as long as you don't confuse yourself). The only exception is that
		3292	you must not do this from C<ev_periodic> reschedule callbacks.
		3293
		3294	Care has been invested into making sure that libev does not keep local
		3295	state inside C<ev_loop>, and other calls do not usually allow coroutine
		3296	switches.
3036		3297
3037		3298
3038	=head1 COMPLEXITIES	3299	=head1 COMPLEXITIES
3039		3300
3040	In this section the complexities of (many of) the algorithms used inside	3301	In this section the complexities of (many of) the algorithms used inside
…		…
3072	correct watcher to remove. The lists are usually short (you don't usually	3333	correct watcher to remove. The lists are usually short (you don't usually
3073	have many watchers waiting for the same fd or signal).	3334	have many watchers waiting for the same fd or signal).
3074		3335
3075	=item Finding the next timer in each loop iteration: O(1)	3336	=item Finding the next timer in each loop iteration: O(1)
3076		3337
3077	By virtue of using a binary heap, the next timer is always found at the	3338	By virtue of using a binary or 4-heap, the next timer is always found at a
3078	beginning of the storage array.	3339	fixed position in the storage array.
3079		3340
3080	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3341	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3081		3342
3082	A change means an I/O watcher gets started or stopped, which requires	3343	A change means an I/O watcher gets started or stopped, which requires
3083	libev to recalculate its status (and possibly tell the kernel, depending	3344	libev to recalculate its status (and possibly tell the kernel, depending
3084	on backend and wether C<ev_io_set> was used).	3345	on backend and whether C<ev_io_set> was used).
3085		3346
3086	=item Activating one watcher (putting it into the pending state): O(1)	3347	=item Activating one watcher (putting it into the pending state): O(1)
3087		3348
3088	=item Priority handling: O(number_of_priorities)	3349	=item Priority handling: O(number_of_priorities)
3089		3350
…		…
3096		3357
3097	=item Processing ev_async_send: O(number_of_async_watchers)	3358	=item Processing ev_async_send: O(number_of_async_watchers)
3098		3359
3099	=item Processing signals: O(max_signal_number)	3360	=item Processing signals: O(max_signal_number)
3100		3361
3101	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3362	Sending involves a system call I<iff> there were no other C<ev_async_send>
3102	calls in the current loop iteration. Checking for async and signal events	3363	calls in the current loop iteration. Checking for async and signal events
3103	involves iterating over all running async watchers or all signal numbers.	3364	involves iterating over all running async watchers or all signal numbers.
3104		3365
3105	=back	3366	=back
3106		3367
3107		3368
3108	=head1 Win32 platform limitations and workarounds	3369	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3109		3370
3110	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3371	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3111	requires, and its I/O model is fundamentally incompatible with the POSIX	3372	requires, and its I/O model is fundamentally incompatible with the POSIX
3112	model. Libev still offers limited functionality on this platform in	3373	model. Libev still offers limited functionality on this platform in
3113	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3374	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3114	descriptors. This only applies when using Win32 natively, not when using	3375	descriptors. This only applies when using Win32 natively, not when using
3115	e.g. cygwin.	3376	e.g. cygwin.
3116		3377
		3378	Lifting these limitations would basically require the full
		3379	re-implementation of the I/O system. If you are into these kinds of
		3380	things, then note that glib does exactly that for you in a very portable
		3381	way (note also that glib is the slowest event library known to man).
		3382
3117	There is no supported compilation method available on windows except	3383	There is no supported compilation method available on windows except
3118	embedding it into other applications.	3384	embedding it into other applications.
3119		3385
		3386	Not a libev limitation but worth mentioning: windows apparently doesn't
		3387	accept large writes: instead of resulting in a partial write, windows will
		3388	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3389	so make sure you only write small amounts into your sockets (less than a
		3390	megabyte seems safe, but thsi apparently depends on the amount of memory
		3391	available).
		3392
3120	Due to the many, low, and arbitrary limits on the win32 platform and the	3393	Due to the many, low, and arbitrary limits on the win32 platform and
3121	abysmal performance of winsockets, using a large number of sockets is not	3394	the abysmal performance of winsockets, using a large number of sockets
3122	recommended (and not reasonable). If your program needs to use more than	3395	is not recommended (and not reasonable). If your program needs to use
3123	a hundred or so sockets, then likely it needs to use a totally different	3396	more than a hundred or so sockets, then likely it needs to use a totally
3124	implementation for windows, as libev offers the POSIX model, which cannot	3397	different implementation for windows, as libev offers the POSIX readiness
3125	be implemented efficiently on windows (microsoft monopoly games).	3398	notification model, which cannot be implemented efficiently on windows
		3399	(Microsoft monopoly games).
		3400
		3401	A typical way to use libev under windows is to embed it (see the embedding
		3402	section for details) and use the following F<evwrap.h> header file instead
		3403	of F<ev.h>:
		3404
		3405	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3406	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3407
		3408	#include "ev.h"
		3409
		3410	And compile the following F<evwrap.c> file into your project (make sure
		3411	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3412
		3413	#include "evwrap.h"
		3414	#include "ev.c"
3126		3415
3127	=over 4	3416	=over 4
3128		3417
3129	=item The winsocket select function	3418	=item The winsocket select function
3130		3419
3131	The winsocket C<select> function doesn't follow POSIX in that it requires	3420	The winsocket C<select> function doesn't follow POSIX in that it
3132	socket I<handles> and not socket I<file descriptors>. This makes select	3421	requires socket I<handles> and not socket I<file descriptors> (it is
3133	very inefficient, and also requires a mapping from file descriptors	3422	also extremely buggy). This makes select very inefficient, and also
3134	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,	3423	requires a mapping from file descriptors to socket handles (the Microsoft
3135	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor	3424	C runtime provides the function C<_open_osfhandle> for this). See the
3136	symbols for more info.	3425	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3426	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3137		3427
3138	The configuration for a "naked" win32 using the microsoft runtime	3428	The configuration for a "naked" win32 using the Microsoft runtime
3139	libraries and raw winsocket select is:	3429	libraries and raw winsocket select is:
3140		3430
3141	#define EV_USE_SELECT 1	3431	#define EV_USE_SELECT 1
3142	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3432	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3143		3433
3144	Note that winsockets handling of fd sets is O(n), so you can easily get a	3434	Note that winsockets handling of fd sets is O(n), so you can easily get a
3145	complexity in the O(n²) range when using win32.	3435	complexity in the O(n²) range when using win32.
3146		3436
3147	=item Limited number of file descriptors	3437	=item Limited number of file descriptors
3148		3438
3149	Windows has numerous arbitrary (and low) limits on things. Early versions	3439	Windows has numerous arbitrary (and low) limits on things.
3150	of winsocket's select only supported waiting for a max. of C<64> handles	3440
		3441	Early versions of winsocket's select only supported waiting for a maximum
3151	(probably owning to the fact that all windows kernels can only wait for	3442	of C<64> handles (probably owning to the fact that all windows kernels
3152	C<64> things at the same time internally; microsoft recommends spawning a	3443	can only wait for C<64> things at the same time internally; Microsoft
3153	chain of threads and wait for 63 handles and the previous thread in each).	3444	recommends spawning a chain of threads and wait for 63 handles and the
		3445	previous thread in each. Great).
3154		3446
3155	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3447	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3156	to some high number (e.g. C<2048>) before compiling the winsocket select	3448	to some high number (e.g. C<2048>) before compiling the winsocket select
3157	call (which might be in libev or elsewhere, for example, perl does its own	3449	call (which might be in libev or elsewhere, for example, perl does its own
3158	select emulation on windows).	3450	select emulation on windows).
3159		3451
3160	Another limit is the number of file descriptors in the microsoft runtime	3452	Another limit is the number of file descriptors in the Microsoft runtime
3161	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3453	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3162	or something like this inside microsoft). You can increase this by calling	3454	or something like this inside Microsoft). You can increase this by calling
3163	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3455	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3164	arbitrary limit), but is broken in many versions of the microsoft runtime	3456	arbitrary limit), but is broken in many versions of the Microsoft runtime
3165	libraries.	3457	libraries.
3166		3458
3167	This might get you to about C<512> or C<2048> sockets (depending on	3459	This might get you to about C<512> or C<2048> sockets (depending on
3168	windows version and/or the phase of the moon). To get more, you need to	3460	windows version and/or the phase of the moon). To get more, you need to
3169	wrap all I/O functions and provide your own fd management, but the cost of	3461	wrap all I/O functions and provide your own fd management, but the cost of
3170	calling select (O(n²)) will likely make this unworkable.	3462	calling select (O(n²)) will likely make this unworkable.
3171		3463
3172	=back	3464	=back
3173		3465
3174		3466
		3467	=head1 PORTABILITY REQUIREMENTS
		3468
		3469	In addition to a working ISO-C implementation, libev relies on a few
		3470	additional extensions:
		3471
		3472	=over 4
		3473
		3474	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3475	calling conventions regardless of C<ev_watcher_type *>.
		3476
		3477	Libev assumes not only that all watcher pointers have the same internal
		3478	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3479	assumes that the same (machine) code can be used to call any watcher
		3480	callback: The watcher callbacks have different type signatures, but libev
		3481	calls them using an C<ev_watcher *> internally.
		3482
		3483	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3484
		3485	The type C<sig_atomic_t volatile> (or whatever is defined as
		3486	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3487	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3488	believed to be sufficiently portable.
		3489
		3490	=item C<sigprocmask> must work in a threaded environment
		3491
		3492	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3493	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3494	pthread implementations will either allow C<sigprocmask> in the "main
		3495	thread" or will block signals process-wide, both behaviours would
		3496	be compatible with libev. Interaction between C<sigprocmask> and
		3497	C<pthread_sigmask> could complicate things, however.
		3498
		3499	The most portable way to handle signals is to block signals in all threads
		3500	except the initial one, and run the default loop in the initial thread as
		3501	well.
		3502
		3503	=item C<long> must be large enough for common memory allocation sizes
		3504
		3505	To improve portability and simplify using libev, libev uses C<long>
		3506	internally instead of C<size_t> when allocating its data structures. On
		3507	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3508	is still at least 31 bits everywhere, which is enough for hundreds of
		3509	millions of watchers.
		3510
		3511	=item C<double> must hold a time value in seconds with enough accuracy
		3512
		3513	The type C<double> is used to represent timestamps. It is required to
		3514	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3515	enough for at least into the year 4000. This requirement is fulfilled by
		3516	implementations implementing IEEE 754 (basically all existing ones).
		3517
		3518	=back
		3519
		3520	If you know of other additional requirements drop me a note.
		3521
		3522
		3523	=head1 COMPILER WARNINGS
		3524
		3525	Depending on your compiler and compiler settings, you might get no or a
		3526	lot of warnings when compiling libev code. Some people are apparently
		3527	scared by this.
		3528
		3529	However, these are unavoidable for many reasons. For one, each compiler
		3530	has different warnings, and each user has different tastes regarding
		3531	warning options. "Warn-free" code therefore cannot be a goal except when
		3532	targeting a specific compiler and compiler-version.
		3533
		3534	Another reason is that some compiler warnings require elaborate
		3535	workarounds, or other changes to the code that make it less clear and less
		3536	maintainable.
		3537
		3538	And of course, some compiler warnings are just plain stupid, or simply
		3539	wrong (because they don't actually warn about the condition their message
		3540	seems to warn about).
		3541
		3542	While libev is written to generate as few warnings as possible,
		3543	"warn-free" code is not a goal, and it is recommended not to build libev
		3544	with any compiler warnings enabled unless you are prepared to cope with
		3545	them (e.g. by ignoring them). Remember that warnings are just that:
		3546	warnings, not errors, or proof of bugs.
		3547
		3548
		3549	=head1 VALGRIND
		3550
		3551	Valgrind has a special section here because it is a popular tool that is
		3552	highly useful, but valgrind reports are very hard to interpret.
		3553
		3554	If you think you found a bug (memory leak, uninitialised data access etc.)
		3555	in libev, then check twice: If valgrind reports something like:
		3556
		3557	==2274== definitely lost: 0 bytes in 0 blocks.
		3558	==2274== possibly lost: 0 bytes in 0 blocks.
		3559	==2274== still reachable: 256 bytes in 1 blocks.
		3560
		3561	Then there is no memory leak. Similarly, under some circumstances,
		3562	valgrind might report kernel bugs as if it were a bug in libev, or it
		3563	might be confused (it is a very good tool, but only a tool).
		3564
		3565	If you are unsure about something, feel free to contact the mailing list
		3566	with the full valgrind report and an explanation on why you think this is
		3567	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3568	no bug" answer and take the chance of learning how to interpret valgrind
		3569	properly.
		3570
		3571	If you need, for some reason, empty reports from valgrind for your project
		3572	I suggest using suppression lists.
		3573
		3574
3175	=head1 AUTHOR	3575	=head1 AUTHOR
3176		3576
3177	Marc Lehmann <libev@schmorp.de>.	3577	Marc Lehmann <libev@schmorp.de>.
3178		3578

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