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Revision 1.146 by root, Fri Apr 11 00:31:19 2008 UTC vs.
Revision 1.172 by root, Wed Aug 6 07:01:25 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
…		…
231	...	252	...
232	ev_set_allocator (persistent_realloc);	253	ev_set_allocator (persistent_realloc);
233		254
234	=item ev_set_syserr_cb (void (*cb)(const char *msg));	255	=item ev_set_syserr_cb (void (*cb)(const char *msg));
235		256
236	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
237	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
238	indicating the system call or subsystem causing the problem. If this	259	indicating the system call or subsystem causing the problem. If this
239	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
240	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
241	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
242	(such as abort).	263	(such as abort).
243		264
244	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.
…		…
277	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,
278	as loops cannot bes hared easily between threads anyway).	299	as loops cannot bes hared easily between threads anyway).
279		300
280	The default loop is the only loop that can handle C<ev_signal> and	301	The default loop is the only loop that can handle C<ev_signal> and
281	C<ev_child> watchers, and to do this, it always registers a handler	302	C<ev_child> watchers, and to do this, it always registers a handler
282	for C<SIGCHLD>. If this is a problem for your app you can either	303	for C<SIGCHLD>. If this is a problem for your application you can either
283	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	304	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
284	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	305	can simply overwrite the C<SIGCHLD> signal handler I<after> calling
285	C<ev_default_init>.	306	C<ev_default_init>.
286		307
287	The flags argument can be used to specify special behaviour or specific	308	The flags argument can be used to specify special behaviour or specific
…		…
296	The default flags value. Use this if you have no clue (it's the right	317	The default flags value. Use this if you have no clue (it's the right
297	thing, believe me).	318	thing, believe me).
298		319
299	=item C<EVFLAG_NOENV>	320	=item C<EVFLAG_NOENV>
300		321
301	If this flag bit is ored into the flag value (or the program runs setuid	322	If this flag bit is or'ed into the flag value (or the program runs setuid
302	or setgid) then libev will I<not> look at the environment variable	323	or setgid) then libev will I<not> look at the environment variable
303	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	324	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
304	override the flags completely if it is found in the environment. This is	325	override the flags completely if it is found in the environment. This is
305	useful to try out specific backends to test their performance, or to work	326	useful to try out specific backends to test their performance, or to work
306	around bugs.	327	around bugs.
…		…
313		334
314	This works by calling C<getpid ()> on every iteration of the loop,	335	This works by calling C<getpid ()> on every iteration of the loop,
315	and thus this might slow down your event loop if you do a lot of loop	336	and thus this might slow down your event loop if you do a lot of loop
316	iterations and little real work, but is usually not noticeable (on my	337	iterations and little real work, but is usually not noticeable (on my
317	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	338	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
318	without a syscall and thus I<very> fast, but my GNU/Linux system also has	339	without a system call and thus I<very> fast, but my GNU/Linux system also has
319	C<pthread_atfork> which is even faster).	340	C<pthread_atfork> which is even faster).
320		341
321	The big advantage of this flag is that you can forget about fork (and	342	The big advantage of this flag is that you can forget about fork (and
322	forget about forgetting to tell libev about forking) when you use this	343	forget about forgetting to tell libev about forking) when you use this
323	flag.	344	flag.
324		345
325	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>	346	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
326	environment variable.	347	environment variable.
327		348
328	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	349	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
329		350
330	This is your standard select(2) backend. Not I<completely> standard, as	351	This is your standard select(2) backend. Not I<completely> standard, as
…		…
332	but if that fails, expect a fairly low limit on the number of fds when	353	but if that fails, expect a fairly low limit on the number of fds when
333	using this backend. It doesn't scale too well (O(highest_fd)), but its	354	using this backend. It doesn't scale too well (O(highest_fd)), but its
334	usually the fastest backend for a low number of (low-numbered :) fds.	355	usually the fastest backend for a low number of (low-numbered :) fds.
335		356
336	To get good performance out of this backend you need a high amount of	357	To get good performance out of this backend you need a high amount of
337	parallelity (most of the file descriptors should be busy). If you are	358	parallelism (most of the file descriptors should be busy). If you are
338	writing a server, you should C<accept ()> in a loop to accept as many	359	writing a server, you should C<accept ()> in a loop to accept as many
339	connections as possible during one iteration. You might also want to have	360	connections as possible during one iteration. You might also want to have
340	a look at C<ev_set_io_collect_interval ()> to increase the amount of	361	a look at C<ev_set_io_collect_interval ()> to increase the amount of
341	readyness notifications you get per iteration.	362	readiness notifications you get per iteration.
342		363
343	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	364	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
344		365
345	And this is your standard poll(2) backend. It's more complicated	366	And this is your standard poll(2) backend. It's more complicated
346	than select, but handles sparse fds better and has no artificial	367	than select, but handles sparse fds better and has no artificial
…		…
354	For few fds, this backend is a bit little slower than poll and select,	375	For few fds, this backend is a bit little slower than poll and select,
355	but it scales phenomenally better. While poll and select usually scale	376	but it scales phenomenally better. While poll and select usually scale
356	like O(total_fds) where n is the total number of fds (or the highest fd),	377	like O(total_fds) where n is the total number of fds (or the highest fd),
357	epoll scales either O(1) or O(active_fds). The epoll design has a number	378	epoll scales either O(1) or O(active_fds). The epoll design has a number
358	of shortcomings, such as silently dropping events in some hard-to-detect	379	of shortcomings, such as silently dropping events in some hard-to-detect
359	cases and requiring a syscall per fd change, no fork support and bad	380	cases and requiring a system call per fd change, no fork support and bad
360	support for dup.	381	support for dup.
361		382
362	While stopping, setting and starting an I/O watcher in the same iteration	383	While stopping, setting and starting an I/O watcher in the same iteration
363	will result in some caching, there is still a syscall per such incident	384	will result in some caching, there is still a system call per such incident
364	(because the fd could point to a different file description now), so its	385	(because the fd could point to a different file description now), so its
365	best to avoid that. Also, C<dup ()>'ed file descriptors might not work	386	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
366	very well if you register events for both fds.	387	very well if you register events for both fds.
367		388
368	Please note that epoll sometimes generates spurious notifications, so you	389	Please note that epoll sometimes generates spurious notifications, so you
…		…
371		392
372	Best performance from this backend is achieved by not unregistering all	393	Best performance from this backend is achieved by not unregistering all
373	watchers for a file descriptor until it has been closed, if possible, i.e.	394	watchers for a file descriptor until it has been closed, if possible, i.e.
374	keep at least one watcher active per fd at all times.	395	keep at least one watcher active per fd at all times.
375		396
376	While nominally embeddeble in other event loops, this feature is broken in	397	While nominally embeddable in other event loops, this feature is broken in
377	all kernel versions tested so far.	398	all kernel versions tested so far.
378		399
379	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	400	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
380		401
381	Kqueue deserves special mention, as at the time of this writing, it	402	Kqueue deserves special mention, as at the time of this writing, it
382	was broken on all BSDs except NetBSD (usually it doesn't work reliably	403	was broken on all BSDs except NetBSD (usually it doesn't work reliably
383	with anything but sockets and pipes, except on Darwin, where of course	404	with anything but sockets and pipes, except on Darwin, where of course
384	it's completely useless). For this reason it's not being "autodetected"	405	it's completely useless). For this reason it's not being "auto-detected"
385	unless you explicitly specify it explicitly in the flags (i.e. using	406	unless you explicitly specify it explicitly in the flags (i.e. using
386	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)	407	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
387	system like NetBSD.	408	system like NetBSD.
388		409
389	You still can embed kqueue into a normal poll or select backend and use it	410	You still can embed kqueue into a normal poll or select backend and use it
…		…
391	the target platform). See C<ev_embed> watchers for more info.	412	the target platform). See C<ev_embed> watchers for more info.
392		413
393	It scales in the same way as the epoll backend, but the interface to the	414	It scales in the same way as the epoll backend, but the interface to the
394	kernel is more efficient (which says nothing about its actual speed, of	415	kernel is more efficient (which says nothing about its actual speed, of
395	course). While stopping, setting and starting an I/O watcher does never	416	course). While stopping, setting and starting an I/O watcher does never
396	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to	417	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
397	two event changes per incident, support for C<fork ()> is very bad and it	418	two event changes per incident, support for C<fork ()> is very bad and it
398	drops fds silently in similarly hard-to-detect cases.	419	drops fds silently in similarly hard-to-detect cases.
399		420
400	This backend usually performs well under most conditions.	421	This backend usually performs well under most conditions.
401		422
…		…
416	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	437	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
417		438
418	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	439	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
419	it's really slow, but it still scales very well (O(active_fds)).	440	it's really slow, but it still scales very well (O(active_fds)).
420		441
421	Please note that solaris event ports can deliver a lot of spurious	442	Please note that Solaris event ports can deliver a lot of spurious
422	notifications, so you need to use non-blocking I/O or other means to avoid	443	notifications, so you need to use non-blocking I/O or other means to avoid
423	blocking when no data (or space) is available.	444	blocking when no data (or space) is available.
424		445
425	While this backend scales well, it requires one system call per active	446	While this backend scales well, it requires one system call per active
426	file descriptor per loop iteration. For small and medium numbers of file	447	file descriptor per loop iteration. For small and medium numbers of file
427	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	448	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
428	might perform better.	449	might perform better.
429		450
430	On the positive side, ignoring the spurious readyness notifications, this	451	On the positive side, ignoring the spurious readiness notifications, this
431	backend actually performed to specification in all tests and is fully	452	backend actually performed to specification in all tests and is fully
432	embeddable, which is a rare feat among the OS-specific backends.	453	embeddable, which is a rare feat among the OS-specific backends.
433		454
434	=item C<EVBACKEND_ALL>	455	=item C<EVBACKEND_ALL>
435		456
…		…
439		460
440	It is definitely not recommended to use this flag.	461	It is definitely not recommended to use this flag.
441		462
442	=back	463	=back
443		464
444	If one or more of these are ored into the flags value, then only these	465	If one or more of these are or'ed into the flags value, then only these
445	backends will be tried (in the reverse order as listed here). If none are	466	backends will be tried (in the reverse order as listed here). If none are
446	specified, all backends in C<ev_recommended_backends ()> will be tried.	467	specified, all backends in C<ev_recommended_backends ()> will be tried.
447		468
448	The most typical usage is like this:	469	The most typical usage is like this:
449		470
450	if (!ev_default_loop (0))	471	if (!ev_default_loop (0))
451	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	472	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
452		473
453	Restrict libev to the select and poll backends, and do not allow	474	Restrict libev to the select and poll backends, and do not allow
454	environment settings to be taken into account:	475	environment settings to be taken into account:
455		476
456	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);	477	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
457		478
458	Use whatever libev has to offer, but make sure that kqueue is used if	479	Use whatever libev has to offer, but make sure that kqueue is used if
459	available (warning, breaks stuff, best use only with your own private	480	available (warning, breaks stuff, best use only with your own private
460	event loop and only if you know the OS supports your types of fds):	481	event loop and only if you know the OS supports your types of fds):
461		482
462	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	483	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
463		484
464	=item struct ev_loop *ev_loop_new (unsigned int flags)	485	=item struct ev_loop *ev_loop_new (unsigned int flags)
465		486
466	Similar to C<ev_default_loop>, but always creates a new event loop that is	487	Similar to C<ev_default_loop>, but always creates a new event loop that is
467	always distinct from the default loop. Unlike the default loop, it cannot	488	always distinct from the default loop. Unlike the default loop, it cannot
…		…
472	libev with threads is indeed to create one loop per thread, and using the	493	libev with threads is indeed to create one loop per thread, and using the
473	default loop in the "main" or "initial" thread.	494	default loop in the "main" or "initial" thread.
474		495
475	Example: Try to create a event loop that uses epoll and nothing else.	496	Example: Try to create a event loop that uses epoll and nothing else.
476		497
477	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	498	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
478	if (!epoller)	499	if (!epoller)
479	fatal ("no epoll found here, maybe it hides under your chair");	500	fatal ("no epoll found here, maybe it hides under your chair");
480		501
481	=item ev_default_destroy ()	502	=item ev_default_destroy ()
482		503
483	Destroys the default loop again (frees all memory and kernel state	504	Destroys the default loop again (frees all memory and kernel state
484	etc.). None of the active event watchers will be stopped in the normal	505	etc.). None of the active event watchers will be stopped in the normal
485	sense, so e.g. C<ev_is_active> might still return true. It is your	506	sense, so e.g. C<ev_is_active> might still return true. It is your
486	responsibility to either stop all watchers cleanly yoursef I<before>	507	responsibility to either stop all watchers cleanly yourself I<before>
487	calling this function, or cope with the fact afterwards (which is usually	508	calling this function, or cope with the fact afterwards (which is usually
488	the easiest thing, you can just ignore the watchers and/or C<free ()> them	509	the easiest thing, you can just ignore the watchers and/or C<free ()> them
489	for example).	510	for example).
490		511
491	Note that certain global state, such as signal state, will not be freed by	512	Note that certain global state, such as signal state, will not be freed by
…		…
572	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	593	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle
573	those events and any outstanding ones, but will not block your process in	594	those events and any outstanding ones, but will not block your process in
574	case there are no events and will return after one iteration of the loop.	595	case there are no events and will return after one iteration of the loop.
575		596
576	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	597	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
577	neccessary) and will handle those and any outstanding ones. It will block	598	necessary) and will handle those and any outstanding ones. It will block
578	your process until at least one new event arrives, and will return after	599	your process until at least one new event arrives, and will return after
579	one iteration of the loop. This is useful if you are waiting for some	600	one iteration of the loop. This is useful if you are waiting for some
580	external event in conjunction with something not expressible using other	601	external event in conjunction with something not expressible using other
581	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	602	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
582	usually a better approach for this kind of thing.	603	usually a better approach for this kind of thing.
583		604
584	Here are the gory details of what C<ev_loop> does:	605	Here are the gory details of what C<ev_loop> does:
585		606
586	- Before the first iteration, call any pending watchers.	607	- Before the first iteration, call any pending watchers.
587	* If EVFLAG_FORKCHECK was used, check for a fork.	608	* If EVFLAG_FORKCHECK was used, check for a fork.
588	- If a fork was detected, queue and call all fork watchers.	609	- If a fork was detected (by any means), queue and call all fork watchers.
589	- Queue and call all prepare watchers.	610	- Queue and call all prepare watchers.
590	- If we have been forked, recreate the kernel state.	611	- If we have been forked, detach and recreate the kernel state
		612	as to not disturb the other process.
591	- Update the kernel state with all outstanding changes.	613	- Update the kernel state with all outstanding changes.
592	- Update the "event loop time".	614	- Update the "event loop time" (ev_now ()).
593	- Calculate for how long to sleep or block, if at all	615	- Calculate for how long to sleep or block, if at all
594	(active idle watchers, EVLOOP_NONBLOCK or not having	616	(active idle watchers, EVLOOP_NONBLOCK or not having
595	any active watchers at all will result in not sleeping).	617	any active watchers at all will result in not sleeping).
596	- Sleep if the I/O and timer collect interval say so.	618	- Sleep if the I/O and timer collect interval say so.
597	- Block the process, waiting for any events.	619	- Block the process, waiting for any events.
598	- Queue all outstanding I/O (fd) events.	620	- Queue all outstanding I/O (fd) events.
599	- Update the "event loop time" and do time jump handling.	621	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
600	- Queue all outstanding timers.	622	- Queue all outstanding timers.
601	- Queue all outstanding periodics.	623	- Queue all outstanding periodics.
602	- If no events are pending now, queue all idle watchers.	624	- Unless any events are pending now, queue all idle watchers.
603	- Queue all check watchers.	625	- Queue all check watchers.
604	- Call all queued watchers in reverse order (i.e. check watchers first).	626	- Call all queued watchers in reverse order (i.e. check watchers first).
605	Signals and child watchers are implemented as I/O watchers, and will	627	Signals and child watchers are implemented as I/O watchers, and will
606	be handled here by queueing them when their watcher gets executed.	628	be handled here by queueing them when their watcher gets executed.
607	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	629	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
…		…
612	anymore.	634	anymore.
613		635
614	... queue jobs here, make sure they register event watchers as long	636	... queue jobs here, make sure they register event watchers as long
615	... as they still have work to do (even an idle watcher will do..)	637	... as they still have work to do (even an idle watcher will do..)
616	ev_loop (my_loop, 0);	638	ev_loop (my_loop, 0);
617	... jobs done. yeah!	639	... jobs done or somebody called unloop. yeah!
618		640
619	=item ev_unloop (loop, how)	641	=item ev_unloop (loop, how)
620		642
621	Can be used to make a call to C<ev_loop> return early (but only after it	643	Can be used to make a call to C<ev_loop> return early (but only after it
622	has processed all outstanding events). The C<how> argument must be either	644	has processed all outstanding events). The C<how> argument must be either
…		…
643	respectively).	665	respectively).
644		666
645	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	667	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
646	running when nothing else is active.	668	running when nothing else is active.
647		669
648	struct ev_signal exitsig;	670	struct ev_signal exitsig;
649	ev_signal_init (&exitsig, sig_cb, SIGINT);	671	ev_signal_init (&exitsig, sig_cb, SIGINT);
650	ev_signal_start (loop, &exitsig);	672	ev_signal_start (loop, &exitsig);
651	evf_unref (loop);	673	evf_unref (loop);
652		674
653	Example: For some weird reason, unregister the above signal handler again.	675	Example: For some weird reason, unregister the above signal handler again.
654		676
655	ev_ref (loop);	677	ev_ref (loop);
656	ev_signal_stop (loop, &exitsig);	678	ev_signal_stop (loop, &exitsig);
657		679
658	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	680	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
659		681
660	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	682	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
661		683
662	These advanced functions influence the time that libev will spend waiting	684	These advanced functions influence the time that libev will spend waiting
663	for events. Both are by default C<0>, meaning that libev will try to	685	for events. Both time intervals are by default C<0>, meaning that libev
664	invoke timer/periodic callbacks and I/O callbacks with minimum latency.	686	will try to invoke timer/periodic callbacks and I/O callbacks with minimum
		687	latency.
665		688
666	Setting these to a higher value (the C<interval> I<must> be >= C<0>)	689	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
667	allows libev to delay invocation of I/O and timer/periodic callbacks to	690	allows libev to delay invocation of I/O and timer/periodic callbacks
668	increase efficiency of loop iterations.	691	to increase efficiency of loop iterations (or to increase power-saving
		692	opportunities).
669		693
670	The background is that sometimes your program runs just fast enough to	694	The background is that sometimes your program runs just fast enough to
671	handle one (or very few) event(s) per loop iteration. While this makes	695	handle one (or very few) event(s) per loop iteration. While this makes
672	the program responsive, it also wastes a lot of CPU time to poll for new	696	the program responsive, it also wastes a lot of CPU time to poll for new
673	events, especially with backends like C<select ()> which have a high	697	events, especially with backends like C<select ()> which have a high
…		…
683	to spend more time collecting timeouts, at the expense of increased	707	to spend more time collecting timeouts, at the expense of increased
684	latency (the watcher callback will be called later). C<ev_io> watchers	708	latency (the watcher callback will be called later). C<ev_io> watchers
685	will not be affected. Setting this to a non-null value will not introduce	709	will not be affected. Setting this to a non-null value will not introduce
686	any overhead in libev.	710	any overhead in libev.
687		711
688	Many (busy) programs can usually benefit by setting the io collect	712	Many (busy) programs can usually benefit by setting the I/O collect
689	interval to a value near C<0.1> or so, which is often enough for	713	interval to a value near C<0.1> or so, which is often enough for
690	interactive servers (of course not for games), likewise for timeouts. It	714	interactive servers (of course not for games), likewise for timeouts. It
691	usually doesn't make much sense to set it to a lower value than C<0.01>,	715	usually doesn't make much sense to set it to a lower value than C<0.01>,
692	as this approsaches the timing granularity of most systems.	716	as this approaches the timing granularity of most systems.
		717
		718	Setting the I<timeout collect interval> can improve the opportunity for
		719	saving power, as the program will "bundle" timer callback invocations that
		720	are "near" in time together, by delaying some, thus reducing the number of
		721	times the process sleeps and wakes up again. Another useful technique to
		722	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
		723	they fire on, say, one-second boundaries only.
		724
		725	=item ev_loop_verify (loop)
		726
		727	This function only does something when C<EV_VERIFY> support has been
		728	compiled in. It tries to go through all internal structures and checks
		729	them for validity. If anything is found to be inconsistent, it will print
		730	an error message to standard error and call C<abort ()>.
		731
		732	This can be used to catch bugs inside libev itself: under normal
		733	circumstances, this function will never abort as of course libev keeps its
		734	data structures consistent.
693		735
694	=back	736	=back
695		737
696		738
697	=head1 ANATOMY OF A WATCHER	739	=head1 ANATOMY OF A WATCHER
698		740
699	A watcher is a structure that you create and register to record your	741	A watcher is a structure that you create and register to record your
700	interest in some event. For instance, if you want to wait for STDIN to	742	interest in some event. For instance, if you want to wait for STDIN to
701	become readable, you would create an C<ev_io> watcher for that:	743	become readable, you would create an C<ev_io> watcher for that:
702		744
703	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	745	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
704	{	746	{
705	ev_io_stop (w);	747	ev_io_stop (w);
706	ev_unloop (loop, EVUNLOOP_ALL);	748	ev_unloop (loop, EVUNLOOP_ALL);
707	}	749	}
708		750
709	struct ev_loop *loop = ev_default_loop (0);	751	struct ev_loop *loop = ev_default_loop (0);
710	struct ev_io stdin_watcher;	752	struct ev_io stdin_watcher;
711	ev_init (&stdin_watcher, my_cb);	753	ev_init (&stdin_watcher, my_cb);
712	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	754	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
713	ev_io_start (loop, &stdin_watcher);	755	ev_io_start (loop, &stdin_watcher);
714	ev_loop (loop, 0);	756	ev_loop (loop, 0);
715		757
716	As you can see, you are responsible for allocating the memory for your	758	As you can see, you are responsible for allocating the memory for your
717	watcher structures (and it is usually a bad idea to do this on the stack,	759	watcher structures (and it is usually a bad idea to do this on the stack,
718	although this can sometimes be quite valid).	760	although this can sometimes be quite valid).
719		761
720	Each watcher structure must be initialised by a call to C<ev_init	762	Each watcher structure must be initialised by a call to C<ev_init
721	(watcher *, callback)>, which expects a callback to be provided. This	763	(watcher *, callback)>, which expects a callback to be provided. This
722	callback gets invoked each time the event occurs (or, in the case of io	764	callback gets invoked each time the event occurs (or, in the case of I/O
723	watchers, each time the event loop detects that the file descriptor given	765	watchers, each time the event loop detects that the file descriptor given
724	is readable and/or writable).	766	is readable and/or writable).
725		767
726	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	768	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro
727	with arguments specific to this watcher type. There is also a macro	769	with arguments specific to this watcher type. There is also a macro
…		…
803		845
804	The given async watcher has been asynchronously notified (see C<ev_async>).	846	The given async watcher has been asynchronously notified (see C<ev_async>).
805		847
806	=item C<EV_ERROR>	848	=item C<EV_ERROR>
807		849
808	An unspecified error has occured, the watcher has been stopped. This might	850	An unspecified error has occurred, the watcher has been stopped. This might
809	happen because the watcher could not be properly started because libev	851	happen because the watcher could not be properly started because libev
810	ran out of memory, a file descriptor was found to be closed or any other	852	ran out of memory, a file descriptor was found to be closed or any other
811	problem. You best act on it by reporting the problem and somehow coping	853	problem. You best act on it by reporting the problem and somehow coping
812	with the watcher being stopped.	854	with the watcher being stopped.
813		855
814	Libev will usually signal a few "dummy" events together with an error,	856	Libev will usually signal a few "dummy" events together with an error,
815	for example it might indicate that a fd is readable or writable, and if	857	for example it might indicate that a fd is readable or writable, and if
816	your callbacks is well-written it can just attempt the operation and cope	858	your callbacks is well-written it can just attempt the operation and cope
817	with the error from read() or write(). This will not work in multithreaded	859	with the error from read() or write(). This will not work in multi-threaded
818	programs, though, so beware.	860	programs, though, so beware.
819		861
820	=back	862	=back
821		863
822	=head2 GENERIC WATCHER FUNCTIONS	864	=head2 GENERIC WATCHER FUNCTIONS
…		…
852	Although some watcher types do not have type-specific arguments	894	Although some watcher types do not have type-specific arguments
853	(e.g. C<ev_prepare>) you still need to call its C<set> macro.	895	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
854		896
855	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	897	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
856		898
857	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	899	This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
858	calls into a single call. This is the most convinient method to initialise	900	calls into a single call. This is the most convenient method to initialise
859	a watcher. The same limitations apply, of course.	901	a watcher. The same limitations apply, of course.
860		902
861	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	903	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
862		904
863	Starts (activates) the given watcher. Only active watchers will receive	905	Starts (activates) the given watcher. Only active watchers will receive
…		…
946	to associate arbitrary data with your watcher. If you need more data and	988	to associate arbitrary data with your watcher. If you need more data and
947	don't want to allocate memory and store a pointer to it in that data	989	don't want to allocate memory and store a pointer to it in that data
948	member, you can also "subclass" the watcher type and provide your own	990	member, you can also "subclass" the watcher type and provide your own
949	data:	991	data:
950		992
951	struct my_io	993	struct my_io
952	{	994	{
953	struct ev_io io;	995	struct ev_io io;
954	int otherfd;	996	int otherfd;
955	void *somedata;	997	void *somedata;
956	struct whatever *mostinteresting;	998	struct whatever *mostinteresting;
957	}	999	}
958		1000
959	And since your callback will be called with a pointer to the watcher, you	1001	And since your callback will be called with a pointer to the watcher, you
960	can cast it back to your own type:	1002	can cast it back to your own type:
961		1003
962	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	1004	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
963	{	1005	{
964	struct my_io *w = (struct my_io *)w_;	1006	struct my_io *w = (struct my_io *)w_;
965	...	1007	...
966	}	1008	}
967		1009
968	More interesting and less C-conformant ways of casting your callback type	1010	More interesting and less C-conformant ways of casting your callback type
969	instead have been omitted.	1011	instead have been omitted.
970		1012
971	Another common scenario is having some data structure with multiple	1013	Another common scenario is having some data structure with multiple
972	watchers:	1014	watchers:
973		1015
974	struct my_biggy	1016	struct my_biggy
975	{	1017	{
976	int some_data;	1018	int some_data;
977	ev_timer t1;	1019	ev_timer t1;
978	ev_timer t2;	1020	ev_timer t2;
979	}	1021	}
980		1022
981	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1023	In this case getting the pointer to C<my_biggy> is a bit more complicated,
982	you need to use C<offsetof>:	1024	you need to use C<offsetof>:
983		1025
984	#include <stddef.h>	1026	#include <stddef.h>
985		1027
986	static void	1028	static void
987	t1_cb (EV_P_ struct ev_timer *w, int revents)	1029	t1_cb (EV_P_ struct ev_timer *w, int revents)
988	{	1030	{
989	struct my_biggy big = (struct my_biggy *	1031	struct my_biggy big = (struct my_biggy *
990	(((char *)w) - offsetof (struct my_biggy, t1));	1032	(((char *)w) - offsetof (struct my_biggy, t1));
991	}	1033	}
992		1034
993	static void	1035	static void
994	t2_cb (EV_P_ struct ev_timer *w, int revents)	1036	t2_cb (EV_P_ struct ev_timer *w, int revents)
995	{	1037	{
996	struct my_biggy big = (struct my_biggy *	1038	struct my_biggy big = (struct my_biggy *
997	(((char *)w) - offsetof (struct my_biggy, t2));	1039	(((char *)w) - offsetof (struct my_biggy, t2));
998	}	1040	}
999		1041
1000		1042
1001	=head1 WATCHER TYPES	1043	=head1 WATCHER TYPES
1002		1044
1003	This section describes each watcher in detail, but will not repeat	1045	This section describes each watcher in detail, but will not repeat
…		…
1032	If you must do this, then force the use of a known-to-be-good backend	1074	If you must do this, then force the use of a known-to-be-good backend
1033	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1075	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
1034	C<EVBACKEND_POLL>).	1076	C<EVBACKEND_POLL>).
1035		1077
1036	Another thing you have to watch out for is that it is quite easy to	1078	Another thing you have to watch out for is that it is quite easy to
1037	receive "spurious" readyness notifications, that is your callback might	1079	receive "spurious" readiness notifications, that is your callback might
1038	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1080	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1039	because there is no data. Not only are some backends known to create a	1081	because there is no data. Not only are some backends known to create a
1040	lot of those (for example solaris ports), it is very easy to get into	1082	lot of those (for example Solaris ports), it is very easy to get into
1041	this situation even with a relatively standard program structure. Thus	1083	this situation even with a relatively standard program structure. Thus
1042	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1084	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1043	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1085	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1044		1086
1045	If you cannot run the fd in non-blocking mode (for example you should not	1087	If you cannot run the fd in non-blocking mode (for example you should not
1046	play around with an Xlib connection), then you have to seperately re-test	1088	play around with an Xlib connection), then you have to separately re-test
1047	whether a file descriptor is really ready with a known-to-be good interface	1089	whether a file descriptor is really ready with a known-to-be good interface
1048	such as poll (fortunately in our Xlib example, Xlib already does this on	1090	such as poll (fortunately in our Xlib example, Xlib already does this on
1049	its own, so its quite safe to use).	1091	its own, so its quite safe to use).
1050		1092
1051	=head3 The special problem of disappearing file descriptors	1093	=head3 The special problem of disappearing file descriptors
…		…
1111	=item ev_io_init (ev_io *, callback, int fd, int events)	1153	=item ev_io_init (ev_io *, callback, int fd, int events)
1112		1154
1113	=item ev_io_set (ev_io *, int fd, int events)	1155	=item ev_io_set (ev_io *, int fd, int events)
1114		1156
1115	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1157	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1116	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1158	receive events for and events is either C<EV_READ>, C<EV_WRITE> or
1117	C<EV_READ | EV_WRITE> to receive the given events.	1159	C<EV_READ | EV_WRITE> to receive the given events.
1118		1160
1119	=item int fd [read-only]	1161	=item int fd [read-only]
1120		1162
1121	The file descriptor being watched.	1163	The file descriptor being watched.
…		…
1130		1172
1131	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1173	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1132	readable, but only once. Since it is likely line-buffered, you could	1174	readable, but only once. Since it is likely line-buffered, you could
1133	attempt to read a whole line in the callback.	1175	attempt to read a whole line in the callback.
1134		1176
1135	static void	1177	static void
1136	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1178	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1137	{	1179	{
1138	ev_io_stop (loop, w);	1180	ev_io_stop (loop, w);
1139	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1181	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1140	}	1182	}
1141		1183
1142	...	1184	...
1143	struct ev_loop *loop = ev_default_init (0);	1185	struct ev_loop *loop = ev_default_init (0);
1144	struct ev_io stdin_readable;	1186	struct ev_io stdin_readable;
1145	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1187	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1146	ev_io_start (loop, &stdin_readable);	1188	ev_io_start (loop, &stdin_readable);
1147	ev_loop (loop, 0);	1189	ev_loop (loop, 0);
1148		1190
1149		1191
1150	=head2 C<ev_timer> - relative and optionally repeating timeouts	1192	=head2 C<ev_timer> - relative and optionally repeating timeouts
1151		1193
1152	Timer watchers are simple relative timers that generate an event after a	1194	Timer watchers are simple relative timers that generate an event after a
1153	given time, and optionally repeating in regular intervals after that.	1195	given time, and optionally repeating in regular intervals after that.
1154		1196
1155	The timers are based on real time, that is, if you register an event that	1197	The timers are based on real time, that is, if you register an event that
1156	times out after an hour and you reset your system clock to last years	1198	times out after an hour and you reset your system clock to January last
1157	time, it will still time out after (roughly) and hour. "Roughly" because	1199	year, it will still time out after (roughly) and hour. "Roughly" because
1158	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1200	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1159	monotonic clock option helps a lot here).	1201	monotonic clock option helps a lot here).
1160		1202
1161	The relative timeouts are calculated relative to the C<ev_now ()>	1203	The relative timeouts are calculated relative to the C<ev_now ()>
1162	time. This is usually the right thing as this timestamp refers to the time	1204	time. This is usually the right thing as this timestamp refers to the time
…		…
1164	you suspect event processing to be delayed and you I<need> to base the timeout	1206	you suspect event processing to be delayed and you I<need> to base the timeout
1165	on the current time, use something like this to adjust for this:	1207	on the current time, use something like this to adjust for this:
1166		1208
1167	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1209	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1168		1210
1169	The callback is guarenteed to be invoked only when its timeout has passed,	1211	The callback is guaranteed to be invoked only after its timeout has passed,
1170	but if multiple timers become ready during the same loop iteration then	1212	but if multiple timers become ready during the same loop iteration then
1171	order of execution is undefined.	1213	order of execution is undefined.
1172		1214
1173	=head3 Watcher-Specific Functions and Data Members	1215	=head3 Watcher-Specific Functions and Data Members
1174		1216
…		…
1176		1218
1177	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1219	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1178		1220
1179	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1221	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1180		1222
1181	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1223	Configure the timer to trigger after C<after> seconds. If C<repeat>
1182	C<0.>, then it will automatically be stopped. If it is positive, then the	1224	is C<0.>, then it will automatically be stopped once the timeout is
1183	timer will automatically be configured to trigger again C<repeat> seconds	1225	reached. If it is positive, then the timer will automatically be
1184	later, again, and again, until stopped manually.	1226	configured to trigger again C<repeat> seconds later, again, and again,
		1227	until stopped manually.
1185		1228
1186	The timer itself will do a best-effort at avoiding drift, that is, if you	1229	The timer itself will do a best-effort at avoiding drift, that is, if
1187	configure a timer to trigger every 10 seconds, then it will trigger at	1230	you configure a timer to trigger every 10 seconds, then it will normally
1188	exactly 10 second intervals. If, however, your program cannot keep up with	1231	trigger at exactly 10 second intervals. If, however, your program cannot
1189	the timer (because it takes longer than those 10 seconds to do stuff) the	1232	keep up with the timer (because it takes longer than those 10 seconds to
1190	timer will not fire more than once per event loop iteration.	1233	do stuff) the timer will not fire more than once per event loop iteration.
1191		1234
1192	=item ev_timer_again (loop, ev_timer *)	1235	=item ev_timer_again (loop, ev_timer *)
1193		1236
1194	This will act as if the timer timed out and restart it again if it is	1237	This will act as if the timer timed out and restart it again if it is
1195	repeating. The exact semantics are:	1238	repeating. The exact semantics are:
1196		1239
1197	If the timer is pending, its pending status is cleared.	1240	If the timer is pending, its pending status is cleared.
1198		1241
1199	If the timer is started but nonrepeating, stop it (as if it timed out).	1242	If the timer is started but non-repeating, stop it (as if it timed out).
1200		1243
1201	If the timer is repeating, either start it if necessary (with the	1244	If the timer is repeating, either start it if necessary (with the
1202	C<repeat> value), or reset the running timer to the C<repeat> value.	1245	C<repeat> value), or reset the running timer to the C<repeat> value.
1203		1246
1204	This sounds a bit complicated, but here is a useful and typical	1247	This sounds a bit complicated, but here is a useful and typical
1205	example: Imagine you have a tcp connection and you want a so-called idle	1248	example: Imagine you have a TCP connection and you want a so-called idle
1206	timeout, that is, you want to be called when there have been, say, 60	1249	timeout, that is, you want to be called when there have been, say, 60
1207	seconds of inactivity on the socket. The easiest way to do this is to	1250	seconds of inactivity on the socket. The easiest way to do this is to
1208	configure an C<ev_timer> with a C<repeat> value of C<60> and then call	1251	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1209	C<ev_timer_again> each time you successfully read or write some data. If	1252	C<ev_timer_again> each time you successfully read or write some data. If
1210	you go into an idle state where you do not expect data to travel on the	1253	you go into an idle state where you do not expect data to travel on the
…		…
1236		1279
1237	=head3 Examples	1280	=head3 Examples
1238		1281
1239	Example: Create a timer that fires after 60 seconds.	1282	Example: Create a timer that fires after 60 seconds.
1240		1283
1241	static void	1284	static void
1242	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1285	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1243	{	1286	{
1244	.. one minute over, w is actually stopped right here	1287	.. one minute over, w is actually stopped right here
1245	}	1288	}
1246		1289
1247	struct ev_timer mytimer;	1290	struct ev_timer mytimer;
1248	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1291	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1249	ev_timer_start (loop, &mytimer);	1292	ev_timer_start (loop, &mytimer);
1250		1293
1251	Example: Create a timeout timer that times out after 10 seconds of	1294	Example: Create a timeout timer that times out after 10 seconds of
1252	inactivity.	1295	inactivity.
1253		1296
1254	static void	1297	static void
1255	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1298	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1256	{	1299	{
1257	.. ten seconds without any activity	1300	.. ten seconds without any activity
1258	}	1301	}
1259		1302
1260	struct ev_timer mytimer;	1303	struct ev_timer mytimer;
1261	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1304	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1262	ev_timer_again (&mytimer); /* start timer */	1305	ev_timer_again (&mytimer); /* start timer */
1263	ev_loop (loop, 0);	1306	ev_loop (loop, 0);
1264		1307
1265	// and in some piece of code that gets executed on any "activity":	1308	// and in some piece of code that gets executed on any "activity":
1266	// reset the timeout to start ticking again at 10 seconds	1309	// reset the timeout to start ticking again at 10 seconds
1267	ev_timer_again (&mytimer);	1310	ev_timer_again (&mytimer);
1268		1311
1269		1312
1270	=head2 C<ev_periodic> - to cron or not to cron?	1313	=head2 C<ev_periodic> - to cron or not to cron?
1271		1314
1272	Periodic watchers are also timers of a kind, but they are very versatile	1315	Periodic watchers are also timers of a kind, but they are very versatile
1273	(and unfortunately a bit complex).	1316	(and unfortunately a bit complex).
1274		1317
1275	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1318	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
1276	but on wallclock time (absolute time). You can tell a periodic watcher	1319	but on wall clock time (absolute time). You can tell a periodic watcher
1277	to trigger "at" some specific point in time. For example, if you tell a	1320	to trigger after some specific point in time. For example, if you tell a
1278	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1321	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()
1279	+ 10.>) and then reset your system clock to the last year, then it will	1322	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1323	clock to January of the previous year, then it will take more than year
1280	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1324	to trigger the event (unlike an C<ev_timer>, which would still trigger
1281	roughly 10 seconds later).	1325	roughly 10 seconds later as it uses a relative timeout).
1282		1326
1283	They can also be used to implement vastly more complex timers, such as	1327	C<ev_periodic>s can also be used to implement vastly more complex timers,
1284	triggering an event on each midnight, local time or other, complicated,	1328	such as triggering an event on each "midnight, local time", or other
1285	rules.	1329	complicated, rules.
1286		1330
1287	As with timers, the callback is guarenteed to be invoked only when the	1331	As with timers, the callback is guaranteed to be invoked only when the
1288	time (C<at>) has been passed, but if multiple periodic timers become ready	1332	time (C<at>) has passed, but if multiple periodic timers become ready
1289	during the same loop iteration then order of execution is undefined.	1333	during the same loop iteration then order of execution is undefined.
1290		1334
1291	=head3 Watcher-Specific Functions and Data Members	1335	=head3 Watcher-Specific Functions and Data Members
1292		1336
1293	=over 4	1337	=over 4
…		…
1301		1345
1302	=over 4	1346	=over 4
1303		1347
1304	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1348	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1305		1349
1306	In this configuration the watcher triggers an event at the wallclock time	1350	In this configuration the watcher triggers an event after the wall clock
1307	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1351	time C<at> has passed and doesn't repeat. It will not adjust when a time
1308	that is, if it is to be run at January 1st 2011 then it will run when the	1352	jump occurs, that is, if it is to be run at January 1st 2011 then it will
1309	system time reaches or surpasses this time.	1353	run when the system time reaches or surpasses this time.
1310		1354
1311	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1355	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1312		1356
1313	In this mode the watcher will always be scheduled to time out at the next	1357	In this mode the watcher will always be scheduled to time out at the next
1314	C<at + N * interval> time (for some integer N, which can also be negative)	1358	C<at + N * interval> time (for some integer N, which can also be negative)
1315	and then repeat, regardless of any time jumps.	1359	and then repeat, regardless of any time jumps.
1316		1360
1317	This can be used to create timers that do not drift with respect to system	1361	This can be used to create timers that do not drift with respect to system
1318	time:	1362	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1363	the hour:
1319		1364
1320	ev_periodic_set (&periodic, 0., 3600., 0);	1365	ev_periodic_set (&periodic, 0., 3600., 0);
1321		1366
1322	This doesn't mean there will always be 3600 seconds in between triggers,	1367	This doesn't mean there will always be 3600 seconds in between triggers,
1323	but only that the the callback will be called when the system time shows a	1368	but only that the callback will be called when the system time shows a
1324	full hour (UTC), or more correctly, when the system time is evenly divisible	1369	full hour (UTC), or more correctly, when the system time is evenly divisible
1325	by 3600.	1370	by 3600.
1326		1371
1327	Another way to think about it (for the mathematically inclined) is that	1372	Another way to think about it (for the mathematically inclined) is that
1328	C<ev_periodic> will try to run the callback in this mode at the next possible	1373	C<ev_periodic> will try to run the callback in this mode at the next possible
1329	time where C<time = at (mod interval)>, regardless of any time jumps.	1374	time where C<time = at (mod interval)>, regardless of any time jumps.
1330		1375
1331	For numerical stability it is preferable that the C<at> value is near	1376	For numerical stability it is preferable that the C<at> value is near
1332	C<ev_now ()> (the current time), but there is no range requirement for	1377	C<ev_now ()> (the current time), but there is no range requirement for
1333	this value.	1378	this value, and in fact is often specified as zero.
		1379
		1380	Note also that there is an upper limit to how often a timer can fire (CPU
		1381	speed for example), so if C<interval> is very small then timing stability
		1382	will of course deteriorate. Libev itself tries to be exact to be about one
		1383	millisecond (if the OS supports it and the machine is fast enough).
1334		1384
1335	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1385	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1336		1386
1337	In this mode the values for C<interval> and C<at> are both being	1387	In this mode the values for C<interval> and C<at> are both being
1338	ignored. Instead, each time the periodic watcher gets scheduled, the	1388	ignored. Instead, each time the periodic watcher gets scheduled, the
1339	reschedule callback will be called with the watcher as first, and the	1389	reschedule callback will be called with the watcher as first, and the
1340	current time as second argument.	1390	current time as second argument.
1341		1391
1342	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1392	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1343	ever, or make any event loop modifications>. If you need to stop it,	1393	ever, or make ANY event loop modifications whatsoever>.
1344	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1345	starting an C<ev_prepare> watcher, which is legal).
1346		1394
		1395	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1396	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1397	only event loop modification you are allowed to do).
		1398
1347	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1399	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1348	ev_tstamp now)>, e.g.:	1400	*w, ev_tstamp now)>, e.g.:
1349		1401
1350	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1402	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1351	{	1403	{
1352	return now + 60.;	1404	return now + 60.;
1353	}	1405	}
…		…
1355	It must return the next time to trigger, based on the passed time value	1407	It must return the next time to trigger, based on the passed time value
1356	(that is, the lowest time value larger than to the second argument). It	1408	(that is, the lowest time value larger than to the second argument). It
1357	will usually be called just before the callback will be triggered, but	1409	will usually be called just before the callback will be triggered, but
1358	might be called at other times, too.	1410	might be called at other times, too.
1359		1411
1360	NOTE: I<< This callback must always return a time that is later than the	1412	NOTE: I<< This callback must always return a time that is higher than or
1361	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.	1413	equal to the passed C<now> value >>.
1362		1414
1363	This can be used to create very complex timers, such as a timer that	1415	This can be used to create very complex timers, such as a timer that
1364	triggers on each midnight, local time. To do this, you would calculate the	1416	triggers on "next midnight, local time". To do this, you would calculate the
1365	next midnight after C<now> and return the timestamp value for this. How	1417	next midnight after C<now> and return the timestamp value for this. How
1366	you do this is, again, up to you (but it is not trivial, which is the main	1418	you do this is, again, up to you (but it is not trivial, which is the main
1367	reason I omitted it as an example).	1419	reason I omitted it as an example).
1368		1420
1369	=back	1421	=back
…		…
1373	Simply stops and restarts the periodic watcher again. This is only useful	1425	Simply stops and restarts the periodic watcher again. This is only useful
1374	when you changed some parameters or the reschedule callback would return	1426	when you changed some parameters or the reschedule callback would return
1375	a different time than the last time it was called (e.g. in a crond like	1427	a different time than the last time it was called (e.g. in a crond like
1376	program when the crontabs have changed).	1428	program when the crontabs have changed).
1377		1429
		1430	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1431
		1432	When active, returns the absolute time that the watcher is supposed to
		1433	trigger next.
		1434
1378	=item ev_tstamp offset [read-write]	1435	=item ev_tstamp offset [read-write]
1379		1436
1380	When repeating, this contains the offset value, otherwise this is the	1437	When repeating, this contains the offset value, otherwise this is the
1381	absolute point in time (the C<at> value passed to C<ev_periodic_set>).	1438	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1382		1439
…		…
1393		1450
1394	The current reschedule callback, or C<0>, if this functionality is	1451	The current reschedule callback, or C<0>, if this functionality is
1395	switched off. Can be changed any time, but changes only take effect when	1452	switched off. Can be changed any time, but changes only take effect when
1396	the periodic timer fires or C<ev_periodic_again> is being called.	1453	the periodic timer fires or C<ev_periodic_again> is being called.
1397		1454
1398	=item ev_tstamp at [read-only]
1399
1400	When active, contains the absolute time that the watcher is supposed to
1401	trigger next.
1402
1403	=back	1455	=back
1404		1456
1405	=head3 Examples	1457	=head3 Examples
1406		1458
1407	Example: Call a callback every hour, or, more precisely, whenever the	1459	Example: Call a callback every hour, or, more precisely, whenever the
1408	system clock is divisible by 3600. The callback invocation times have	1460	system clock is divisible by 3600. The callback invocation times have
1409	potentially a lot of jittering, but good long-term stability.	1461	potentially a lot of jitter, but good long-term stability.
1410		1462
1411	static void	1463	static void
1412	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1464	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1413	{	1465	{
1414	... its now a full hour (UTC, or TAI or whatever your clock follows)	1466	... its now a full hour (UTC, or TAI or whatever your clock follows)
1415	}	1467	}
1416		1468
1417	struct ev_periodic hourly_tick;	1469	struct ev_periodic hourly_tick;
1418	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1470	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1419	ev_periodic_start (loop, &hourly_tick);	1471	ev_periodic_start (loop, &hourly_tick);
1420		1472
1421	Example: The same as above, but use a reschedule callback to do it:	1473	Example: The same as above, but use a reschedule callback to do it:
1422		1474
1423	#include <math.h>	1475	#include <math.h>
1424		1476
1425	static ev_tstamp	1477	static ev_tstamp
1426	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1478	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1427	{	1479	{
1428	return fmod (now, 3600.) + 3600.;	1480	return fmod (now, 3600.) + 3600.;
1429	}	1481	}
1430		1482
1431	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1483	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1432		1484
1433	Example: Call a callback every hour, starting now:	1485	Example: Call a callback every hour, starting now:
1434		1486
1435	struct ev_periodic hourly_tick;	1487	struct ev_periodic hourly_tick;
1436	ev_periodic_init (&hourly_tick, clock_cb,	1488	ev_periodic_init (&hourly_tick, clock_cb,
1437	fmod (ev_now (loop), 3600.), 3600., 0);	1489	fmod (ev_now (loop), 3600.), 3600., 0);
1438	ev_periodic_start (loop, &hourly_tick);	1490	ev_periodic_start (loop, &hourly_tick);
1439		1491
1440		1492
1441	=head2 C<ev_signal> - signal me when a signal gets signalled!	1493	=head2 C<ev_signal> - signal me when a signal gets signalled!
1442		1494
1443	Signal watchers will trigger an event when the process receives a specific	1495	Signal watchers will trigger an event when the process receives a specific
…		…
1451	as you don't register any with libev). Similarly, when the last signal	1503	as you don't register any with libev). Similarly, when the last signal
1452	watcher for a signal is stopped libev will reset the signal handler to	1504	watcher for a signal is stopped libev will reset the signal handler to
1453	SIG_DFL (regardless of what it was set to before).	1505	SIG_DFL (regardless of what it was set to before).
1454		1506
1455	If possible and supported, libev will install its handlers with	1507	If possible and supported, libev will install its handlers with
1456	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1508	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1457	interrupted. If you have a problem with syscalls getting interrupted by	1509	interrupted. If you have a problem with system calls getting interrupted by
1458	signals you can block all signals in an C<ev_check> watcher and unblock	1510	signals you can block all signals in an C<ev_check> watcher and unblock
1459	them in an C<ev_prepare> watcher.	1511	them in an C<ev_prepare> watcher.
1460		1512
1461	=head3 Watcher-Specific Functions and Data Members	1513	=head3 Watcher-Specific Functions and Data Members
1462		1514
…		…
1477		1529
1478	=head3 Examples	1530	=head3 Examples
1479		1531
1480	Example: Try to exit cleanly on SIGINT and SIGTERM.	1532	Example: Try to exit cleanly on SIGINT and SIGTERM.
1481		1533
1482	static void	1534	static void
1483	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1535	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1484	{	1536	{
1485	ev_unloop (loop, EVUNLOOP_ALL);	1537	ev_unloop (loop, EVUNLOOP_ALL);
1486	}	1538	}
1487		1539
1488	struct ev_signal signal_watcher;	1540	struct ev_signal signal_watcher;
1489	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1541	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1490	ev_signal_start (loop, &sigint_cb);	1542	ev_signal_start (loop, &sigint_cb);
1491		1543
1492		1544
1493	=head2 C<ev_child> - watch out for process status changes	1545	=head2 C<ev_child> - watch out for process status changes
1494		1546
1495	Child watchers trigger when your process receives a SIGCHLD in response to	1547	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1497	is permissible to install a child watcher I<after> the child has been	1549	is permissible to install a child watcher I<after> the child has been
1498	forked (which implies it might have already exited), as long as the event	1550	forked (which implies it might have already exited), as long as the event
1499	loop isn't entered (or is continued from a watcher).	1551	loop isn't entered (or is continued from a watcher).
1500		1552
1501	Only the default event loop is capable of handling signals, and therefore	1553	Only the default event loop is capable of handling signals, and therefore
1502	you can only rgeister child watchers in the default event loop.	1554	you can only register child watchers in the default event loop.
1503		1555
1504	=head3 Process Interaction	1556	=head3 Process Interaction
1505		1557
1506	Libev grabs C<SIGCHLD> as soon as the default event loop is	1558	Libev grabs C<SIGCHLD> as soon as the default event loop is
1507	initialised. This is necessary to guarantee proper behaviour even if	1559	initialised. This is necessary to guarantee proper behaviour even if
1508	the first child watcher is started after the child exits. The occurance	1560	the first child watcher is started after the child exits. The occurrence
1509	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1561	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1510	synchronously as part of the event loop processing. Libev always reaps all	1562	synchronously as part of the event loop processing. Libev always reaps all
1511	children, even ones not watched.	1563	children, even ones not watched.
1512		1564
1513	=head3 Overriding the Built-In Processing	1565	=head3 Overriding the Built-In Processing
…		…
1555	=head3 Examples	1607	=head3 Examples
1556		1608
1557	Example: C<fork()> a new process and install a child handler to wait for	1609	Example: C<fork()> a new process and install a child handler to wait for
1558	its completion.	1610	its completion.
1559		1611
1560	ev_child cw;	1612	ev_child cw;
1561		1613
1562	static void	1614	static void
1563	child_cb (EV_P_ struct ev_child *w, int revents)	1615	child_cb (EV_P_ struct ev_child *w, int revents)
1564	{	1616	{
1565	ev_child_stop (EV_A_ w);	1617	ev_child_stop (EV_A_ w);
1566	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1618	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1567	}	1619	}
1568		1620
1569	pid_t pid = fork ();	1621	pid_t pid = fork ();
1570		1622
1571	if (pid < 0)	1623	if (pid < 0)
1572	// error	1624	// error
1573	else if (pid == 0)	1625	else if (pid == 0)
1574	{	1626	{
1575	// the forked child executes here	1627	// the forked child executes here
1576	exit (1);	1628	exit (1);
1577	}	1629	}
1578	else	1630	else
1579	{	1631	{
1580	ev_child_init (&cw, child_cb, pid, 0);	1632	ev_child_init (&cw, child_cb, pid, 0);
1581	ev_child_start (EV_DEFAULT_ &cw);	1633	ev_child_start (EV_DEFAULT_ &cw);
1582	}	1634	}
1583		1635
1584		1636
1585	=head2 C<ev_stat> - did the file attributes just change?	1637	=head2 C<ev_stat> - did the file attributes just change?
1586		1638
1587	This watches a filesystem path for attribute changes. That is, it calls	1639	This watches a file system path for attribute changes. That is, it calls
1588	C<stat> regularly (or when the OS says it changed) and sees if it changed	1640	C<stat> regularly (or when the OS says it changed) and sees if it changed
1589	compared to the last time, invoking the callback if it did.	1641	compared to the last time, invoking the callback if it did.
1590		1642
1591	The path does not need to exist: changing from "path exists" to "path does	1643	The path does not need to exist: changing from "path exists" to "path does
1592	not exist" is a status change like any other. The condition "path does	1644	not exist" is a status change like any other. The condition "path does
…		…
1610	as even with OS-supported change notifications, this can be	1662	as even with OS-supported change notifications, this can be
1611	resource-intensive.	1663	resource-intensive.
1612		1664
1613	At the time of this writing, only the Linux inotify interface is	1665	At the time of this writing, only the Linux inotify interface is
1614	implemented (implementing kqueue support is left as an exercise for the	1666	implemented (implementing kqueue support is left as an exercise for the
		1667	reader, note, however, that the author sees no way of implementing ev_stat
1615	reader). Inotify will be used to give hints only and should not change the	1668	semantics with kqueue). Inotify will be used to give hints only and should
1616	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1669	not change the semantics of C<ev_stat> watchers, which means that libev
1617	to fall back to regular polling again even with inotify, but changes are	1670	sometimes needs to fall back to regular polling again even with inotify,
1618	usually detected immediately, and if the file exists there will be no	1671	but changes are usually detected immediately, and if the file exists there
1619	polling.	1672	will be no polling.
1620		1673
1621	=head3 ABI Issues (Largefile Support)	1674	=head3 ABI Issues (Largefile Support)
1622		1675
1623	Libev by default (unless the user overrides this) uses the default	1676	Libev by default (unless the user overrides this) uses the default
1624	compilation environment, which means that on systems with optionally	1677	compilation environment, which means that on systems with large file
1625	disabled large file support, you get the 32 bit version of the stat	1678	support disabled by default, you get the 32 bit version of the stat
1626	structure. When using the library from programs that change the ABI to	1679	structure. When using the library from programs that change the ABI to
1627	use 64 bit file offsets the programs will fail. In that case you have to	1680	use 64 bit file offsets the programs will fail. In that case you have to
1628	compile libev with the same flags to get binary compatibility. This is	1681	compile libev with the same flags to get binary compatibility. This is
1629	obviously the case with any flags that change the ABI, but the problem is	1682	obviously the case with any flags that change the ABI, but the problem is
1630	most noticably with ev_stat and largefile support.	1683	most noticeably disabled with ev_stat and large file support.
		1684
		1685	The solution for this is to lobby your distribution maker to make large
		1686	file interfaces available by default (as e.g. FreeBSD does) and not
		1687	optional. Libev cannot simply switch on large file support because it has
		1688	to exchange stat structures with application programs compiled using the
		1689	default compilation environment.
1631		1690
1632	=head3 Inotify	1691	=head3 Inotify
1633		1692
1634	When C<inotify (7)> support has been compiled into libev (generally only	1693	When C<inotify (7)> support has been compiled into libev (generally only
1635	available on Linux) and present at runtime, it will be used to speed up	1694	available on Linux) and present at runtime, it will be used to speed up
1636	change detection where possible. The inotify descriptor will be created lazily	1695	change detection where possible. The inotify descriptor will be created lazily
1637	when the first C<ev_stat> watcher is being started.	1696	when the first C<ev_stat> watcher is being started.
1638		1697
1639	Inotify presense does not change the semantics of C<ev_stat> watchers	1698	Inotify presence does not change the semantics of C<ev_stat> watchers
1640	except that changes might be detected earlier, and in some cases, to avoid	1699	except that changes might be detected earlier, and in some cases, to avoid
1641	making regular C<stat> calls. Even in the presense of inotify support	1700	making regular C<stat> calls. Even in the presence of inotify support
1642	there are many cases where libev has to resort to regular C<stat> polling.	1701	there are many cases where libev has to resort to regular C<stat> polling.
1643		1702
1644	(There is no support for kqueue, as apparently it cannot be used to	1703	(There is no support for kqueue, as apparently it cannot be used to
1645	implement this functionality, due to the requirement of having a file	1704	implement this functionality, due to the requirement of having a file
1646	descriptor open on the object at all times).	1705	descriptor open on the object at all times).
1647		1706
1648	=head3 The special problem of stat time resolution	1707	=head3 The special problem of stat time resolution
1649		1708
1650	The C<stat ()> syscall only supports full-second resolution portably, and	1709	The C<stat ()> system call only supports full-second resolution portably, and
1651	even on systems where the resolution is higher, many filesystems still	1710	even on systems where the resolution is higher, many file systems still
1652	only support whole seconds.	1711	only support whole seconds.
1653		1712
1654	That means that, if the time is the only thing that changes, you might	1713	That means that, if the time is the only thing that changes, you can
1655	miss updates: on the first update, C<ev_stat> detects a change and calls	1714	easily miss updates: on the first update, C<ev_stat> detects a change and
1656	your callback, which does something. When there is another update within	1715	calls your callback, which does something. When there is another update
1657	the same second, C<ev_stat> will be unable to detect it.	1716	within the same second, C<ev_stat> will be unable to detect it as the stat
		1717	data does not change.
1658		1718
1659	The solution to this is to delay acting on a change for a second (or till	1719	The solution to this is to delay acting on a change for slightly more
1660	the next second boundary), using a roughly one-second delay C<ev_timer>	1720	than a second (or till slightly after the next full second boundary), using
1661	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>	1721	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);
1662	is added to work around small timing inconsistencies of some operating	1722	ev_timer_again (loop, w)>).
1663	systems.	1723
		1724	The C<.02> offset is added to work around small timing inconsistencies
		1725	of some operating systems (where the second counter of the current time
		1726	might be be delayed. One such system is the Linux kernel, where a call to
		1727	C<gettimeofday> might return a timestamp with a full second later than
		1728	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1729	update file times then there will be a small window where the kernel uses
		1730	the previous second to update file times but libev might already execute
		1731	the timer callback).
1664		1732
1665	=head3 Watcher-Specific Functions and Data Members	1733	=head3 Watcher-Specific Functions and Data Members
1666		1734
1667	=over 4	1735	=over 4
1668		1736
…		…
1674	C<path>. The C<interval> is a hint on how quickly a change is expected to	1742	C<path>. The C<interval> is a hint on how quickly a change is expected to
1675	be detected and should normally be specified as C<0> to let libev choose	1743	be detected and should normally be specified as C<0> to let libev choose
1676	a suitable value. The memory pointed to by C<path> must point to the same	1744	a suitable value. The memory pointed to by C<path> must point to the same
1677	path for as long as the watcher is active.	1745	path for as long as the watcher is active.
1678		1746
1679	The callback will be receive C<EV_STAT> when a change was detected,	1747	The callback will receive C<EV_STAT> when a change was detected, relative
1680	relative to the attributes at the time the watcher was started (or the	1748	to the attributes at the time the watcher was started (or the last change
1681	last change was detected).	1749	was detected).
1682		1750
1683	=item ev_stat_stat (loop, ev_stat *)	1751	=item ev_stat_stat (loop, ev_stat *)
1684		1752
1685	Updates the stat buffer immediately with new values. If you change the	1753	Updates the stat buffer immediately with new values. If you change the
1686	watched path in your callback, you could call this fucntion to avoid	1754	watched path in your callback, you could call this function to avoid
1687	detecting this change (while introducing a race condition). Can also be	1755	detecting this change (while introducing a race condition if you are not
1688	useful simply to find out the new values.	1756	the only one changing the path). Can also be useful simply to find out the
		1757	new values.
1689		1758
1690	=item ev_statdata attr [read-only]	1759	=item ev_statdata attr [read-only]
1691		1760
1692	The most-recently detected attributes of the file. Although the type is of	1761	The most-recently detected attributes of the file. Although the type is
1693	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types	1762	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
1694	suitable for your system. If the C<st_nlink> member is C<0>, then there	1763	suitable for your system, but you can only rely on the POSIX-standardised
		1764	members to be present. If the C<st_nlink> member is C<0>, then there was
1695	was some error while C<stat>ing the file.	1765	some error while C<stat>ing the file.
1696		1766
1697	=item ev_statdata prev [read-only]	1767	=item ev_statdata prev [read-only]
1698		1768
1699	The previous attributes of the file. The callback gets invoked whenever	1769	The previous attributes of the file. The callback gets invoked whenever
1700	C<prev> != C<attr>.	1770	C<prev> != C<attr>, or, more precisely, one or more of these members
		1771	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1772	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1701		1773
1702	=item ev_tstamp interval [read-only]	1774	=item ev_tstamp interval [read-only]
1703		1775
1704	The specified interval.	1776	The specified interval.
1705		1777
1706	=item const char *path [read-only]	1778	=item const char *path [read-only]
1707		1779
1708	The filesystem path that is being watched.	1780	The file system path that is being watched.
1709		1781
1710	=back	1782	=back
1711		1783
1712	=head3 Examples	1784	=head3 Examples
1713		1785
1714	Example: Watch C</etc/passwd> for attribute changes.	1786	Example: Watch C</etc/passwd> for attribute changes.
1715		1787
1716	static void	1788	static void
1717	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1789	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1718	{	1790	{
1719	/* /etc/passwd changed in some way */	1791	/* /etc/passwd changed in some way */
1720	if (w->attr.st_nlink)	1792	if (w->attr.st_nlink)
1721	{	1793	{
1722	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1794	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1723	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1795	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1724	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1796	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1725	}	1797	}
1726	else	1798	else
1727	/* you shalt not abuse printf for puts */	1799	/* you shalt not abuse printf for puts */
1728	puts ("wow, /etc/passwd is not there, expect problems. "	1800	puts ("wow, /etc/passwd is not there, expect problems. "
1729	"if this is windows, they already arrived\n");	1801	"if this is windows, they already arrived\n");
1730	}	1802	}
1731		1803
1732	...	1804	...
1733	ev_stat passwd;	1805	ev_stat passwd;
1734		1806
1735	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1807	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1736	ev_stat_start (loop, &passwd);	1808	ev_stat_start (loop, &passwd);
1737		1809
1738	Example: Like above, but additionally use a one-second delay so we do not	1810	Example: Like above, but additionally use a one-second delay so we do not
1739	miss updates (however, frequent updates will delay processing, too, so	1811	miss updates (however, frequent updates will delay processing, too, so
1740	one might do the work both on C<ev_stat> callback invocation I<and> on	1812	one might do the work both on C<ev_stat> callback invocation I<and> on
1741	C<ev_timer> callback invocation).	1813	C<ev_timer> callback invocation).
1742		1814
1743	static ev_stat passwd;	1815	static ev_stat passwd;
1744	static ev_timer timer;	1816	static ev_timer timer;
1745		1817
1746	static void	1818	static void
1747	timer_cb (EV_P_ ev_timer *w, int revents)	1819	timer_cb (EV_P_ ev_timer *w, int revents)
1748	{	1820	{
1749	ev_timer_stop (EV_A_ w);	1821	ev_timer_stop (EV_A_ w);
1750		1822
1751	/* now it's one second after the most recent passwd change */	1823	/* now it's one second after the most recent passwd change */
1752	}	1824	}
1753		1825
1754	static void	1826	static void
1755	stat_cb (EV_P_ ev_stat *w, int revents)	1827	stat_cb (EV_P_ ev_stat *w, int revents)
1756	{	1828	{
1757	/* reset the one-second timer */	1829	/* reset the one-second timer */
1758	ev_timer_again (EV_A_ &timer);	1830	ev_timer_again (EV_A_ &timer);
1759	}	1831	}
1760		1832
1761	...	1833	...
1762	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1834	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1763	ev_stat_start (loop, &passwd);	1835	ev_stat_start (loop, &passwd);
1764	ev_timer_init (&timer, timer_cb, 0., 1.01);	1836	ev_timer_init (&timer, timer_cb, 0., 1.02);
1765		1837
1766		1838
1767	=head2 C<ev_idle> - when you've got nothing better to do...	1839	=head2 C<ev_idle> - when you've got nothing better to do...
1768		1840
1769	Idle watchers trigger events when no other events of the same or higher	1841	Idle watchers trigger events when no other events of the same or higher
…		…
1800	=head3 Examples	1872	=head3 Examples
1801		1873
1802	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1874	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1803	callback, free it. Also, use no error checking, as usual.	1875	callback, free it. Also, use no error checking, as usual.
1804		1876
1805	static void	1877	static void
1806	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1878	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1807	{	1879	{
1808	free (w);	1880	free (w);
1809	// now do something you wanted to do when the program has	1881	// now do something you wanted to do when the program has
1810	// no longer anything immediate to do.	1882	// no longer anything immediate to do.
1811	}	1883	}
1812		1884
1813	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1885	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1814	ev_idle_init (idle_watcher, idle_cb);	1886	ev_idle_init (idle_watcher, idle_cb);
1815	ev_idle_start (loop, idle_cb);	1887	ev_idle_start (loop, idle_cb);
1816		1888
1817		1889
1818	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1890	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1819		1891
1820	Prepare and check watchers are usually (but not always) used in tandem:	1892	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1839		1911
1840	This is done by examining in each prepare call which file descriptors need	1912	This is done by examining in each prepare call which file descriptors need
1841	to be watched by the other library, registering C<ev_io> watchers for	1913	to be watched by the other library, registering C<ev_io> watchers for
1842	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1914	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1843	provide just this functionality). Then, in the check watcher you check for	1915	provide just this functionality). Then, in the check watcher you check for
1844	any events that occured (by checking the pending status of all watchers	1916	any events that occurred (by checking the pending status of all watchers
1845	and stopping them) and call back into the library. The I/O and timer	1917	and stopping them) and call back into the library. The I/O and timer
1846	callbacks will never actually be called (but must be valid nevertheless,	1918	callbacks will never actually be called (but must be valid nevertheless,
1847	because you never know, you know?).	1919	because you never know, you know?).
1848		1920
1849	As another example, the Perl Coro module uses these hooks to integrate	1921	As another example, the Perl Coro module uses these hooks to integrate
…		…
1857		1929
1858	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1930	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
1859	priority, to ensure that they are being run before any other watchers	1931	priority, to ensure that they are being run before any other watchers
1860	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,	1932	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
1861	too) should not activate ("feed") events into libev. While libev fully	1933	too) should not activate ("feed") events into libev. While libev fully
1862	supports this, they will be called before other C<ev_check> watchers	1934	supports this, they might get executed before other C<ev_check> watchers
1863	did their job. As C<ev_check> watchers are often used to embed other	1935	did their job. As C<ev_check> watchers are often used to embed other
1864	(non-libev) event loops those other event loops might be in an unusable	1936	(non-libev) event loops those other event loops might be in an unusable
1865	state until their C<ev_check> watcher ran (always remind yourself to	1937	state until their C<ev_check> watcher ran (always remind yourself to
1866	coexist peacefully with others).	1938	coexist peacefully with others).
1867		1939
…		…
1882	=head3 Examples	1954	=head3 Examples
1883		1955
1884	There are a number of principal ways to embed other event loops or modules	1956	There are a number of principal ways to embed other event loops or modules
1885	into libev. Here are some ideas on how to include libadns into libev	1957	into libev. Here are some ideas on how to include libadns into libev
1886	(there is a Perl module named C<EV::ADNS> that does this, which you could	1958	(there is a Perl module named C<EV::ADNS> that does this, which you could
1887	use for an actually working example. Another Perl module named C<EV::Glib>	1959	use as a working example. Another Perl module named C<EV::Glib> embeds a
1888	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV	1960	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1889	into the Glib event loop).	1961	Glib event loop).
1890		1962
1891	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	1963	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1892	and in a check watcher, destroy them and call into libadns. What follows	1964	and in a check watcher, destroy them and call into libadns. What follows
1893	is pseudo-code only of course. This requires you to either use a low	1965	is pseudo-code only of course. This requires you to either use a low
1894	priority for the check watcher or use C<ev_clear_pending> explicitly, as	1966	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1895	the callbacks for the IO/timeout watchers might not have been called yet.	1967	the callbacks for the IO/timeout watchers might not have been called yet.
1896		1968
1897	static ev_io iow [nfd];	1969	static ev_io iow [nfd];
1898	static ev_timer tw;	1970	static ev_timer tw;
1899		1971
1900	static void	1972	static void
1901	io_cb (ev_loop *loop, ev_io *w, int revents)	1973	io_cb (ev_loop *loop, ev_io *w, int revents)
1902	{	1974	{
1903	}	1975	}
1904		1976
1905	// create io watchers for each fd and a timer before blocking	1977	// create io watchers for each fd and a timer before blocking
1906	static void	1978	static void
1907	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1979	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1908	{	1980	{
1909	int timeout = 3600000;	1981	int timeout = 3600000;
1910	struct pollfd fds [nfd];	1982	struct pollfd fds [nfd];
1911	// actual code will need to loop here and realloc etc.	1983	// actual code will need to loop here and realloc etc.
1912	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1984	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1913		1985
1914	/* the callback is illegal, but won't be called as we stop during check */	1986	/* the callback is illegal, but won't be called as we stop during check */
1915	ev_timer_init (&tw, 0, timeout * 1e-3);	1987	ev_timer_init (&tw, 0, timeout * 1e-3);
1916	ev_timer_start (loop, &tw);	1988	ev_timer_start (loop, &tw);
1917		1989
1918	// create one ev_io per pollfd	1990	// create one ev_io per pollfd
1919	for (int i = 0; i < nfd; ++i)	1991	for (int i = 0; i < nfd; ++i)
1920	{	1992	{
1921	ev_io_init (iow + i, io_cb, fds [i].fd,	1993	ev_io_init (iow + i, io_cb, fds [i].fd,
1922	((fds [i].events & POLLIN ? EV_READ : 0)	1994	((fds [i].events & POLLIN ? EV_READ : 0)
1923	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1995	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1924		1996
1925	fds [i].revents = 0;	1997	fds [i].revents = 0;
1926	ev_io_start (loop, iow + i);	1998	ev_io_start (loop, iow + i);
1927	}	1999	}
1928	}	2000	}
1929		2001
1930	// stop all watchers after blocking	2002	// stop all watchers after blocking
1931	static void	2003	static void
1932	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	2004	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1933	{	2005	{
1934	ev_timer_stop (loop, &tw);	2006	ev_timer_stop (loop, &tw);
1935		2007
1936	for (int i = 0; i < nfd; ++i)	2008	for (int i = 0; i < nfd; ++i)
1937	{	2009	{
1938	// set the relevant poll flags	2010	// set the relevant poll flags
1939	// could also call adns_processreadable etc. here	2011	// could also call adns_processreadable etc. here
1940	struct pollfd *fd = fds + i;	2012	struct pollfd *fd = fds + i;
1941	int revents = ev_clear_pending (iow + i);	2013	int revents = ev_clear_pending (iow + i);
1942	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	2014	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1943	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	2015	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1944		2016
1945	// now stop the watcher	2017	// now stop the watcher
1946	ev_io_stop (loop, iow + i);	2018	ev_io_stop (loop, iow + i);
1947	}	2019	}
1948		2020
1949	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2021	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1950	}	2022	}
1951		2023
1952	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2024	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
1953	in the prepare watcher and would dispose of the check watcher.	2025	in the prepare watcher and would dispose of the check watcher.
1954		2026
1955	Method 3: If the module to be embedded supports explicit event	2027	Method 3: If the module to be embedded supports explicit event
1956	notification (adns does), you can also make use of the actual watcher	2028	notification (libadns does), you can also make use of the actual watcher
1957	callbacks, and only destroy/create the watchers in the prepare watcher.	2029	callbacks, and only destroy/create the watchers in the prepare watcher.
1958		2030
1959	static void	2031	static void
1960	timer_cb (EV_P_ ev_timer *w, int revents)	2032	timer_cb (EV_P_ ev_timer *w, int revents)
1961	{	2033	{
1962	adns_state ads = (adns_state)w->data;	2034	adns_state ads = (adns_state)w->data;
1963	update_now (EV_A);	2035	update_now (EV_A);
1964		2036
1965	adns_processtimeouts (ads, &tv_now);	2037	adns_processtimeouts (ads, &tv_now);
1966	}	2038	}
1967		2039
1968	static void	2040	static void
1969	io_cb (EV_P_ ev_io *w, int revents)	2041	io_cb (EV_P_ ev_io *w, int revents)
1970	{	2042	{
1971	adns_state ads = (adns_state)w->data;	2043	adns_state ads = (adns_state)w->data;
1972	update_now (EV_A);	2044	update_now (EV_A);
1973		2045
1974	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2046	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1975	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2047	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1976	}	2048	}
1977		2049
1978	// do not ever call adns_afterpoll	2050	// do not ever call adns_afterpoll
1979		2051
1980	Method 4: Do not use a prepare or check watcher because the module you	2052	Method 4: Do not use a prepare or check watcher because the module you
1981	want to embed is too inflexible to support it. Instead, youc na override	2053	want to embed is too inflexible to support it. Instead, you can override
1982	their poll function. The drawback with this solution is that the main	2054	their poll function. The drawback with this solution is that the main
1983	loop is now no longer controllable by EV. The C<Glib::EV> module does	2055	loop is now no longer controllable by EV. The C<Glib::EV> module does
1984	this.	2056	this.
1985		2057
1986	static gint	2058	static gint
1987	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2059	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1988	{	2060	{
1989	int got_events = 0;	2061	int got_events = 0;
1990		2062
1991	for (n = 0; n < nfds; ++n)	2063	for (n = 0; n < nfds; ++n)
1992	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2064	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1993		2065
1994	if (timeout >= 0)	2066	if (timeout >= 0)
1995	// create/start timer	2067	// create/start timer
1996		2068
1997	// poll	2069	// poll
1998	ev_loop (EV_A_ 0);	2070	ev_loop (EV_A_ 0);
1999		2071
2000	// stop timer again	2072	// stop timer again
2001	if (timeout >= 0)	2073	if (timeout >= 0)
2002	ev_timer_stop (EV_A_ &to);	2074	ev_timer_stop (EV_A_ &to);
2003		2075
2004	// stop io watchers again - their callbacks should have set	2076	// stop io watchers again - their callbacks should have set
2005	for (n = 0; n < nfds; ++n)	2077	for (n = 0; n < nfds; ++n)
2006	ev_io_stop (EV_A_ iow [n]);	2078	ev_io_stop (EV_A_ iow [n]);
2007		2079
2008	return got_events;	2080	return got_events;
2009	}	2081	}
2010		2082
2011		2083
2012	=head2 C<ev_embed> - when one backend isn't enough...	2084	=head2 C<ev_embed> - when one backend isn't enough...
2013		2085
2014	This is a rather advanced watcher type that lets you embed one event loop	2086	This is a rather advanced watcher type that lets you embed one event loop
…		…
2070		2142
2071	Configures the watcher to embed the given loop, which must be	2143	Configures the watcher to embed the given loop, which must be
2072	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be	2144	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
2073	invoked automatically, otherwise it is the responsibility of the callback	2145	invoked automatically, otherwise it is the responsibility of the callback
2074	to invoke it (it will continue to be called until the sweep has been done,	2146	to invoke it (it will continue to be called until the sweep has been done,
2075	if you do not want thta, you need to temporarily stop the embed watcher).	2147	if you do not want that, you need to temporarily stop the embed watcher).
2076		2148
2077	=item ev_embed_sweep (loop, ev_embed *)	2149	=item ev_embed_sweep (loop, ev_embed *)
2078		2150
2079	Make a single, non-blocking sweep over the embedded loop. This works	2151	Make a single, non-blocking sweep over the embedded loop. This works
2080	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2152	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2081	apropriate way for embedded loops.	2153	appropriate way for embedded loops.
2082		2154
2083	=item struct ev_loop *other [read-only]	2155	=item struct ev_loop *other [read-only]
2084		2156
2085	The embedded event loop.	2157	The embedded event loop.
2086		2158
…		…
2088		2160
2089	=head3 Examples	2161	=head3 Examples
2090		2162
2091	Example: Try to get an embeddable event loop and embed it into the default	2163	Example: Try to get an embeddable event loop and embed it into the default
2092	event loop. If that is not possible, use the default loop. The default	2164	event loop. If that is not possible, use the default loop. The default
2093	loop is stored in C<loop_hi>, while the mebeddable loop is stored in	2165	loop is stored in C<loop_hi>, while the embeddable loop is stored in
2094	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be	2166	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2095	used).	2167	used).
2096		2168
2097	struct ev_loop *loop_hi = ev_default_init (0);	2169	struct ev_loop *loop_hi = ev_default_init (0);
2098	struct ev_loop *loop_lo = 0;	2170	struct ev_loop *loop_lo = 0;
2099	struct ev_embed embed;	2171	struct ev_embed embed;
2100		2172
2101	// see if there is a chance of getting one that works	2173	// see if there is a chance of getting one that works
2102	// (remember that a flags value of 0 means autodetection)	2174	// (remember that a flags value of 0 means autodetection)
2103	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2175	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2104	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2176	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2105	: 0;	2177	: 0;
2106		2178
2107	// if we got one, then embed it, otherwise default to loop_hi	2179	// if we got one, then embed it, otherwise default to loop_hi
2108	if (loop_lo)	2180	if (loop_lo)
2109	{	2181	{
2110	ev_embed_init (&embed, 0, loop_lo);	2182	ev_embed_init (&embed, 0, loop_lo);
2111	ev_embed_start (loop_hi, &embed);	2183	ev_embed_start (loop_hi, &embed);
2112	}	2184	}
2113	else	2185	else
2114	loop_lo = loop_hi;	2186	loop_lo = loop_hi;
2115		2187
2116	Example: Check if kqueue is available but not recommended and create	2188	Example: Check if kqueue is available but not recommended and create
2117	a kqueue backend for use with sockets (which usually work with any	2189	a kqueue backend for use with sockets (which usually work with any
2118	kqueue implementation). Store the kqueue/socket-only event loop in	2190	kqueue implementation). Store the kqueue/socket-only event loop in
2119	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2191	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2120		2192
2121	struct ev_loop *loop = ev_default_init (0);	2193	struct ev_loop *loop = ev_default_init (0);
2122	struct ev_loop *loop_socket = 0;	2194	struct ev_loop *loop_socket = 0;
2123	struct ev_embed embed;	2195	struct ev_embed embed;
2124		2196
2125	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2197	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2126	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2198	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2127	{	2199	{
2128	ev_embed_init (&embed, 0, loop_socket);	2200	ev_embed_init (&embed, 0, loop_socket);
2129	ev_embed_start (loop, &embed);	2201	ev_embed_start (loop, &embed);
2130	}	2202	}
2131		2203
2132	if (!loop_socket)	2204	if (!loop_socket)
2133	loop_socket = loop;	2205	loop_socket = loop;
2134		2206
2135	// now use loop_socket for all sockets, and loop for everything else	2207	// now use loop_socket for all sockets, and loop for everything else
2136		2208
2137		2209
2138	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2210	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2139		2211
2140	Fork watchers are called when a C<fork ()> was detected (usually because	2212	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2193		2265
2194	=item queueing from a signal handler context	2266	=item queueing from a signal handler context
2195		2267
2196	To implement race-free queueing, you simply add to the queue in the signal	2268	To implement race-free queueing, you simply add to the queue in the signal
2197	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2269	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2198	some fictitiuous SIGUSR1 handler:	2270	some fictitious SIGUSR1 handler:
2199		2271
2200	static ev_async mysig;	2272	static ev_async mysig;
2201		2273
2202	static void	2274	static void
2203	sigusr1_handler (void)	2275	sigusr1_handler (void)
…		…
2277	=item ev_async_send (loop, ev_async *)	2349	=item ev_async_send (loop, ev_async *)
2278		2350
2279	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2351	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2280	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2352	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2281	C<ev_feed_event>, this call is safe to do in other threads, signal or	2353	C<ev_feed_event>, this call is safe to do in other threads, signal or
2282	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding	2354	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2283	section below on what exactly this means).	2355	section below on what exactly this means).
2284		2356
2285	This call incurs the overhead of a syscall only once per loop iteration,	2357	This call incurs the overhead of a system call only once per loop iteration,
2286	so while the overhead might be noticable, it doesn't apply to repeated	2358	so while the overhead might be noticeable, it doesn't apply to repeated
2287	calls to C<ev_async_send>.	2359	calls to C<ev_async_send>.
2288		2360
2289	=item bool = ev_async_pending (ev_async *)	2361	=item bool = ev_async_pending (ev_async *)
2290		2362
2291	Returns a non-zero value when C<ev_async_send> has been called on the	2363	Returns a non-zero value when C<ev_async_send> has been called on the
…		…
2293	event loop.	2365	event loop.
2294		2366
2295	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When	2367	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
2296	the loop iterates next and checks for the watcher to have become active,	2368	the loop iterates next and checks for the watcher to have become active,
2297	it will reset the flag again. C<ev_async_pending> can be used to very	2369	it will reset the flag again. C<ev_async_pending> can be used to very
2298	quickly check wether invoking the loop might be a good idea.	2370	quickly check whether invoking the loop might be a good idea.
2299		2371
2300	Not that this does I<not> check wether the watcher itself is pending, only	2372	Not that this does I<not> check whether the watcher itself is pending, only
2301	wether it has been requested to make this watcher pending.	2373	whether it has been requested to make this watcher pending.
2302		2374
2303	=back	2375	=back
2304		2376
2305		2377
2306	=head1 OTHER FUNCTIONS	2378	=head1 OTHER FUNCTIONS
…		…
2317	or timeout without having to allocate/configure/start/stop/free one or	2389	or timeout without having to allocate/configure/start/stop/free one or
2318	more watchers yourself.	2390	more watchers yourself.
2319		2391
2320	If C<fd> is less than 0, then no I/O watcher will be started and events	2392	If C<fd> is less than 0, then no I/O watcher will be started and events
2321	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2393	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2322	C<events> set will be craeted and started.	2394	C<events> set will be created and started.
2323		2395
2324	If C<timeout> is less than 0, then no timeout watcher will be	2396	If C<timeout> is less than 0, then no timeout watcher will be
2325	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2397	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2326	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2398	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2327	dubious value.	2399	dubious value.
…		…
2329	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2401	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2330	passed an C<revents> set like normal event callbacks (a combination of	2402	passed an C<revents> set like normal event callbacks (a combination of
2331	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2403	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2332	value passed to C<ev_once>:	2404	value passed to C<ev_once>:
2333		2405
2334	static void stdin_ready (int revents, void *arg)	2406	static void stdin_ready (int revents, void *arg)
2335	{	2407	{
2336	if (revents & EV_TIMEOUT)	2408	if (revents & EV_TIMEOUT)
2337	/* doh, nothing entered */;	2409	/* doh, nothing entered */;
2338	else if (revents & EV_READ)	2410	else if (revents & EV_READ)
2339	/* stdin might have data for us, joy! */;	2411	/* stdin might have data for us, joy! */;
2340	}	2412	}
2341		2413
2342	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2414	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2343		2415
2344	=item ev_feed_event (ev_loop *, watcher *, int revents)	2416	=item ev_feed_event (ev_loop *, watcher *, int revents)
2345		2417
2346	Feeds the given event set into the event loop, as if the specified event	2418	Feeds the given event set into the event loop, as if the specified event
2347	had happened for the specified watcher (which must be a pointer to an	2419	had happened for the specified watcher (which must be a pointer to an
…		…
2352	Feed an event on the given fd, as if a file descriptor backend detected	2424	Feed an event on the given fd, as if a file descriptor backend detected
2353	the given events it.	2425	the given events it.
2354		2426
2355	=item ev_feed_signal_event (ev_loop *loop, int signum)	2427	=item ev_feed_signal_event (ev_loop *loop, int signum)
2356		2428
2357	Feed an event as if the given signal occured (C<loop> must be the default	2429	Feed an event as if the given signal occurred (C<loop> must be the default
2358	loop!).	2430	loop!).
2359		2431
2360	=back	2432	=back
2361		2433
2362		2434
…		…
2391	=back	2463	=back
2392		2464
2393	=head1 C++ SUPPORT	2465	=head1 C++ SUPPORT
2394		2466
2395	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2467	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2396	you to use some convinience methods to start/stop watchers and also change	2468	you to use some convenience methods to start/stop watchers and also change
2397	the callback model to a model using method callbacks on objects.	2469	the callback model to a model using method callbacks on objects.
2398		2470
2399	To use it,	2471	To use it,
2400		2472
2401	#include <ev++.h>	2473	#include <ev++.h>
2402		2474
2403	This automatically includes F<ev.h> and puts all of its definitions (many	2475	This automatically includes F<ev.h> and puts all of its definitions (many
2404	of them macros) into the global namespace. All C++ specific things are	2476	of them macros) into the global namespace. All C++ specific things are
2405	put into the C<ev> namespace. It should support all the same embedding	2477	put into the C<ev> namespace. It should support all the same embedding
2406	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2478	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2473	your compiler is good :), then the method will be fully inlined into the	2545	your compiler is good :), then the method will be fully inlined into the
2474	thunking function, making it as fast as a direct C callback.	2546	thunking function, making it as fast as a direct C callback.
2475		2547
2476	Example: simple class declaration and watcher initialisation	2548	Example: simple class declaration and watcher initialisation
2477		2549
2478	struct myclass	2550	struct myclass
2479	{	2551	{
2480	void io_cb (ev::io &w, int revents) { }	2552	void io_cb (ev::io &w, int revents) { }
2481	}	2553	}
2482		2554
2483	myclass obj;	2555	myclass obj;
2484	ev::io iow;	2556	ev::io iow;
2485	iow.set <myclass, &myclass::io_cb> (&obj);	2557	iow.set <myclass, &myclass::io_cb> (&obj);
2486		2558
2487	=item w->set<function> (void *data = 0)	2559	=item w->set<function> (void *data = 0)
2488		2560
2489	Also sets a callback, but uses a static method or plain function as	2561	Also sets a callback, but uses a static method or plain function as
2490	callback. The optional C<data> argument will be stored in the watcher's	2562	callback. The optional C<data> argument will be stored in the watcher's
…		…
2494		2566
2495	See the method-C<set> above for more details.	2567	See the method-C<set> above for more details.
2496		2568
2497	Example:	2569	Example:
2498		2570
2499	static void io_cb (ev::io &w, int revents) { }	2571	static void io_cb (ev::io &w, int revents) { }
2500	iow.set <io_cb> ();	2572	iow.set <io_cb> ();
2501		2573
2502	=item w->set (struct ev_loop *)	2574	=item w->set (struct ev_loop *)
2503		2575
2504	Associates a different C<struct ev_loop> with this watcher. You can only	2576	Associates a different C<struct ev_loop> with this watcher. You can only
2505	do this when the watcher is inactive (and not pending either).	2577	do this when the watcher is inactive (and not pending either).
2506		2578
2507	=item w->set ([args])	2579	=item w->set ([arguments])
2508		2580
2509	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2581	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2510	called at least once. Unlike the C counterpart, an active watcher gets	2582	called at least once. Unlike the C counterpart, an active watcher gets
2511	automatically stopped and restarted when reconfiguring it with this	2583	automatically stopped and restarted when reconfiguring it with this
2512	method.	2584	method.
2513		2585
2514	=item w->start ()	2586	=item w->start ()
…		…
2538	=back	2610	=back
2539		2611
2540	Example: Define a class with an IO and idle watcher, start one of them in	2612	Example: Define a class with an IO and idle watcher, start one of them in
2541	the constructor.	2613	the constructor.
2542		2614
2543	class myclass	2615	class myclass
2544	{	2616	{
2545	ev::io io; void io_cb (ev::io &w, int revents);	2617	ev::io io; void io_cb (ev::io &w, int revents);
2546	ev:idle idle void idle_cb (ev::idle &w, int revents);	2618	ev:idle idle void idle_cb (ev::idle &w, int revents);
2547		2619
2548	myclass (int fd)	2620	myclass (int fd)
2549	{	2621	{
2550	io .set <myclass, &myclass::io_cb > (this);	2622	io .set <myclass, &myclass::io_cb > (this);
2551	idle.set <myclass, &myclass::idle_cb> (this);	2623	idle.set <myclass, &myclass::idle_cb> (this);
2552		2624
2553	io.start (fd, ev::READ);	2625	io.start (fd, ev::READ);
2554	}	2626	}
2555	};	2627	};
2556		2628
2557		2629
2558	=head1 OTHER LANGUAGE BINDINGS	2630	=head1 OTHER LANGUAGE BINDINGS
2559		2631
2560	Libev does not offer other language bindings itself, but bindings for a	2632	Libev does not offer other language bindings itself, but bindings for a
2561	numbe rof languages exist in the form of third-party packages. If you know	2633	number of languages exist in the form of third-party packages. If you know
2562	any interesting language binding in addition to the ones listed here, drop	2634	any interesting language binding in addition to the ones listed here, drop
2563	me a note.	2635	me a note.
2564		2636
2565	=over 4	2637	=over 4
2566		2638
…		…
2570	libev. EV is developed together with libev. Apart from the EV core module,	2642	libev. EV is developed together with libev. Apart from the EV core module,
2571	there are additional modules that implement libev-compatible interfaces	2643	there are additional modules that implement libev-compatible interfaces
2572	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the	2644	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
2573	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).	2645	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2574		2646
2575	It can be found and installed via CPAN, its homepage is found at	2647	It can be found and installed via CPAN, its homepage is at
2576	L<http://software.schmorp.de/pkg/EV>.	2648	L<http://software.schmorp.de/pkg/EV>.
2577		2649
		2650	=item Python
		2651
		2652	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2653	seems to be quite complete and well-documented. Note, however, that the
		2654	patch they require for libev is outright dangerous as it breaks the ABI
		2655	for everybody else, and therefore, should never be applied in an installed
		2656	libev (if python requires an incompatible ABI then it needs to embed
		2657	libev).
		2658
2578	=item Ruby	2659	=item Ruby
2579		2660
2580	Tony Arcieri has written a ruby extension that offers access to a subset	2661	Tony Arcieri has written a ruby extension that offers access to a subset
2581	of the libev API and adds filehandle abstractions, asynchronous DNS and	2662	of the libev API and adds file handle abstractions, asynchronous DNS and
2582	more on top of it. It can be found via gem servers. Its homepage is at	2663	more on top of it. It can be found via gem servers. Its homepage is at
2583	L<http://rev.rubyforge.org/>.	2664	L<http://rev.rubyforge.org/>.
2584		2665
2585	=item D	2666	=item D
2586		2667
2587	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	2668	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
2588	be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.	2669	be found at L<http://proj.llucax.com.ar/wiki/evd>.
2589		2670
2590	=back	2671	=back
2591		2672
2592		2673
2593	=head1 MACRO MAGIC	2674	=head1 MACRO MAGIC
2594		2675
2595	Libev can be compiled with a variety of options, the most fundamantal	2676	Libev can be compiled with a variety of options, the most fundamental
2596	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2677	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2597	functions and callbacks have an initial C<struct ev_loop *> argument.	2678	functions and callbacks have an initial C<struct ev_loop *> argument.
2598		2679
2599	To make it easier to write programs that cope with either variant, the	2680	To make it easier to write programs that cope with either variant, the
2600	following macros are defined:	2681	following macros are defined:
…		…
2605		2686
2606	This provides the loop I<argument> for functions, if one is required ("ev	2687	This provides the loop I<argument> for functions, if one is required ("ev
2607	loop argument"). The C<EV_A> form is used when this is the sole argument,	2688	loop argument"). The C<EV_A> form is used when this is the sole argument,
2608	C<EV_A_> is used when other arguments are following. Example:	2689	C<EV_A_> is used when other arguments are following. Example:
2609		2690
2610	ev_unref (EV_A);	2691	ev_unref (EV_A);
2611	ev_timer_add (EV_A_ watcher);	2692	ev_timer_add (EV_A_ watcher);
2612	ev_loop (EV_A_ 0);	2693	ev_loop (EV_A_ 0);
2613		2694
2614	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2695	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2615	which is often provided by the following macro.	2696	which is often provided by the following macro.
2616		2697
2617	=item C<EV_P>, C<EV_P_>	2698	=item C<EV_P>, C<EV_P_>
2618		2699
2619	This provides the loop I<parameter> for functions, if one is required ("ev	2700	This provides the loop I<parameter> for functions, if one is required ("ev
2620	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2701	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2621	C<EV_P_> is used when other parameters are following. Example:	2702	C<EV_P_> is used when other parameters are following. Example:
2622		2703
2623	// this is how ev_unref is being declared	2704	// this is how ev_unref is being declared
2624	static void ev_unref (EV_P);	2705	static void ev_unref (EV_P);
2625		2706
2626	// this is how you can declare your typical callback	2707	// this is how you can declare your typical callback
2627	static void cb (EV_P_ ev_timer *w, int revents)	2708	static void cb (EV_P_ ev_timer *w, int revents)
2628		2709
2629	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2710	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2630	suitable for use with C<EV_A>.	2711	suitable for use with C<EV_A>.
2631		2712
2632	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2713	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
…		…
2648		2729
2649	Example: Declare and initialise a check watcher, utilising the above	2730	Example: Declare and initialise a check watcher, utilising the above
2650	macros so it will work regardless of whether multiple loops are supported	2731	macros so it will work regardless of whether multiple loops are supported
2651	or not.	2732	or not.
2652		2733
2653	static void	2734	static void
2654	check_cb (EV_P_ ev_timer *w, int revents)	2735	check_cb (EV_P_ ev_timer *w, int revents)
2655	{	2736	{
2656	ev_check_stop (EV_A_ w);	2737	ev_check_stop (EV_A_ w);
2657	}	2738	}
2658		2739
2659	ev_check check;	2740	ev_check check;
2660	ev_check_init (&check, check_cb);	2741	ev_check_init (&check, check_cb);
2661	ev_check_start (EV_DEFAULT_ &check);	2742	ev_check_start (EV_DEFAULT_ &check);
2662	ev_loop (EV_DEFAULT_ 0);	2743	ev_loop (EV_DEFAULT_ 0);
2663		2744
2664	=head1 EMBEDDING	2745	=head1 EMBEDDING
2665		2746
2666	Libev can (and often is) directly embedded into host	2747	Libev can (and often is) directly embedded into host
2667	applications. Examples of applications that embed it include the Deliantra	2748	applications. Examples of applications that embed it include the Deliantra
…		…
2674	libev somewhere in your source tree).	2755	libev somewhere in your source tree).
2675		2756
2676	=head2 FILESETS	2757	=head2 FILESETS
2677		2758
2678	Depending on what features you need you need to include one or more sets of files	2759	Depending on what features you need you need to include one or more sets of files
2679	in your app.	2760	in your application.
2680		2761
2681	=head3 CORE EVENT LOOP	2762	=head3 CORE EVENT LOOP
2682		2763
2683	To include only the libev core (all the C<ev_*> functions), with manual	2764	To include only the libev core (all the C<ev_*> functions), with manual
2684	configuration (no autoconf):	2765	configuration (no autoconf):
2685		2766
2686	#define EV_STANDALONE 1	2767	#define EV_STANDALONE 1
2687	#include "ev.c"	2768	#include "ev.c"
2688		2769
2689	This will automatically include F<ev.h>, too, and should be done in a	2770	This will automatically include F<ev.h>, too, and should be done in a
2690	single C source file only to provide the function implementations. To use	2771	single C source file only to provide the function implementations. To use
2691	it, do the same for F<ev.h> in all files wishing to use this API (best	2772	it, do the same for F<ev.h> in all files wishing to use this API (best
2692	done by writing a wrapper around F<ev.h> that you can include instead and	2773	done by writing a wrapper around F<ev.h> that you can include instead and
2693	where you can put other configuration options):	2774	where you can put other configuration options):
2694		2775
2695	#define EV_STANDALONE 1	2776	#define EV_STANDALONE 1
2696	#include "ev.h"	2777	#include "ev.h"
2697		2778
2698	Both header files and implementation files can be compiled with a C++	2779	Both header files and implementation files can be compiled with a C++
2699	compiler (at least, thats a stated goal, and breakage will be treated	2780	compiler (at least, thats a stated goal, and breakage will be treated
2700	as a bug).	2781	as a bug).
2701		2782
2702	You need the following files in your source tree, or in a directory	2783	You need the following files in your source tree, or in a directory
2703	in your include path (e.g. in libev/ when using -Ilibev):	2784	in your include path (e.g. in libev/ when using -Ilibev):
2704		2785
2705	ev.h	2786	ev.h
2706	ev.c	2787	ev.c
2707	ev_vars.h	2788	ev_vars.h
2708	ev_wrap.h	2789	ev_wrap.h
2709		2790
2710	ev_win32.c required on win32 platforms only	2791	ev_win32.c required on win32 platforms only
2711		2792
2712	ev_select.c only when select backend is enabled (which is enabled by default)	2793	ev_select.c only when select backend is enabled (which is enabled by default)
2713	ev_poll.c only when poll backend is enabled (disabled by default)	2794	ev_poll.c only when poll backend is enabled (disabled by default)
2714	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2795	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2715	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2796	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2716	ev_port.c only when the solaris port backend is enabled (disabled by default)	2797	ev_port.c only when the solaris port backend is enabled (disabled by default)
2717		2798
2718	F<ev.c> includes the backend files directly when enabled, so you only need	2799	F<ev.c> includes the backend files directly when enabled, so you only need
2719	to compile this single file.	2800	to compile this single file.
2720		2801
2721	=head3 LIBEVENT COMPATIBILITY API	2802	=head3 LIBEVENT COMPATIBILITY API
2722		2803
2723	To include the libevent compatibility API, also include:	2804	To include the libevent compatibility API, also include:
2724		2805
2725	#include "event.c"	2806	#include "event.c"
2726		2807
2727	in the file including F<ev.c>, and:	2808	in the file including F<ev.c>, and:
2728		2809
2729	#include "event.h"	2810	#include "event.h"
2730		2811
2731	in the files that want to use the libevent API. This also includes F<ev.h>.	2812	in the files that want to use the libevent API. This also includes F<ev.h>.
2732		2813
2733	You need the following additional files for this:	2814	You need the following additional files for this:
2734		2815
2735	event.h	2816	event.h
2736	event.c	2817	event.c
2737		2818
2738	=head3 AUTOCONF SUPPORT	2819	=head3 AUTOCONF SUPPORT
2739		2820
2740	Instead of using C<EV_STANDALONE=1> and providing your config in	2821	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2741	whatever way you want, you can also C<m4_include([libev.m4])> in your	2822	whatever way you want, you can also C<m4_include([libev.m4])> in your
2742	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2823	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2743	include F<config.h> and configure itself accordingly.	2824	include F<config.h> and configure itself accordingly.
2744		2825
2745	For this of course you need the m4 file:	2826	For this of course you need the m4 file:
2746		2827
2747	libev.m4	2828	libev.m4
2748		2829
2749	=head2 PREPROCESSOR SYMBOLS/MACROS	2830	=head2 PREPROCESSOR SYMBOLS/MACROS
2750		2831
2751	Libev can be configured via a variety of preprocessor symbols you have to	2832	Libev can be configured via a variety of preprocessor symbols you have to
2752	define before including any of its files. The default in the absense of	2833	define before including any of its files. The default in the absence of
2753	autoconf is noted for every option.	2834	autoconf is noted for every option.
2754		2835
2755	=over 4	2836	=over 4
2756		2837
2757	=item EV_STANDALONE	2838	=item EV_STANDALONE
…		…
2763	F<event.h> that are not directly supported by the libev core alone.	2844	F<event.h> that are not directly supported by the libev core alone.
2764		2845
2765	=item EV_USE_MONOTONIC	2846	=item EV_USE_MONOTONIC
2766		2847
2767	If defined to be C<1>, libev will try to detect the availability of the	2848	If defined to be C<1>, libev will try to detect the availability of the
2768	monotonic clock option at both compiletime and runtime. Otherwise no use	2849	monotonic clock option at both compile time and runtime. Otherwise no use
2769	of the monotonic clock option will be attempted. If you enable this, you	2850	of the monotonic clock option will be attempted. If you enable this, you
2770	usually have to link against librt or something similar. Enabling it when	2851	usually have to link against librt or something similar. Enabling it when
2771	the functionality isn't available is safe, though, although you have	2852	the functionality isn't available is safe, though, although you have
2772	to make sure you link against any libraries where the C<clock_gettime>	2853	to make sure you link against any libraries where the C<clock_gettime>
2773	function is hiding in (often F<-lrt>).	2854	function is hiding in (often F<-lrt>).
2774		2855
2775	=item EV_USE_REALTIME	2856	=item EV_USE_REALTIME
2776		2857
2777	If defined to be C<1>, libev will try to detect the availability of the	2858	If defined to be C<1>, libev will try to detect the availability of the
2778	realtime clock option at compiletime (and assume its availability at	2859	real-time clock option at compile time (and assume its availability at
2779	runtime if successful). Otherwise no use of the realtime clock option will	2860	runtime if successful). Otherwise no use of the real-time clock option will
2780	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2861	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2781	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2862	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2782	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2863	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2783		2864
2784	=item EV_USE_NANOSLEEP	2865	=item EV_USE_NANOSLEEP
…		…
2795	2.7 or newer, otherwise disabled.	2876	2.7 or newer, otherwise disabled.
2796		2877
2797	=item EV_USE_SELECT	2878	=item EV_USE_SELECT
2798		2879
2799	If undefined or defined to be C<1>, libev will compile in support for the	2880	If undefined or defined to be C<1>, libev will compile in support for the
2800	C<select>(2) backend. No attempt at autodetection will be done: if no	2881	C<select>(2) backend. No attempt at auto-detection will be done: if no
2801	other method takes over, select will be it. Otherwise the select backend	2882	other method takes over, select will be it. Otherwise the select backend
2802	will not be compiled in.	2883	will not be compiled in.
2803		2884
2804	=item EV_SELECT_USE_FD_SET	2885	=item EV_SELECT_USE_FD_SET
2805		2886
2806	If defined to C<1>, then the select backend will use the system C<fd_set>	2887	If defined to C<1>, then the select backend will use the system C<fd_set>
2807	structure. This is useful if libev doesn't compile due to a missing	2888	structure. This is useful if libev doesn't compile due to a missing
2808	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	2889	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
2809	exotic systems. This usually limits the range of file descriptors to some	2890	exotic systems. This usually limits the range of file descriptors to some
2810	low limit such as 1024 or might have other limitations (winsocket only	2891	low limit such as 1024 or might have other limitations (winsocket only
2811	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	2892	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2812	influence the size of the C<fd_set> used.	2893	influence the size of the C<fd_set> used.
2813		2894
…		…
2862	otherwise another method will be used as fallback. This is the preferred	2943	otherwise another method will be used as fallback. This is the preferred
2863	backend for Solaris 10 systems.	2944	backend for Solaris 10 systems.
2864		2945
2865	=item EV_USE_DEVPOLL	2946	=item EV_USE_DEVPOLL
2866		2947
2867	reserved for future expansion, works like the USE symbols above.	2948	Reserved for future expansion, works like the USE symbols above.
2868		2949
2869	=item EV_USE_INOTIFY	2950	=item EV_USE_INOTIFY
2870		2951
2871	If defined to be C<1>, libev will compile in support for the Linux inotify	2952	If defined to be C<1>, libev will compile in support for the Linux inotify
2872	interface to speed up C<ev_stat> watchers. Its actual availability will	2953	interface to speed up C<ev_stat> watchers. Its actual availability will
…		…
2879	access is atomic with respect to other threads or signal contexts. No such	2960	access is atomic with respect to other threads or signal contexts. No such
2880	type is easily found in the C language, so you can provide your own type	2961	type is easily found in the C language, so you can provide your own type
2881	that you know is safe for your purposes. It is used both for signal handler "locking"	2962	that you know is safe for your purposes. It is used both for signal handler "locking"
2882	as well as for signal and thread safety in C<ev_async> watchers.	2963	as well as for signal and thread safety in C<ev_async> watchers.
2883		2964
2884	In the absense of this define, libev will use C<sig_atomic_t volatile>	2965	In the absence of this define, libev will use C<sig_atomic_t volatile>
2885	(from F<signal.h>), which is usually good enough on most platforms.	2966	(from F<signal.h>), which is usually good enough on most platforms.
2886		2967
2887	=item EV_H	2968	=item EV_H
2888		2969
2889	The name of the F<ev.h> header file used to include it. The default if	2970	The name of the F<ev.h> header file used to include it. The default if
…		…
2928	When doing priority-based operations, libev usually has to linearly search	3009	When doing priority-based operations, libev usually has to linearly search
2929	all the priorities, so having many of them (hundreds) uses a lot of space	3010	all the priorities, so having many of them (hundreds) uses a lot of space
2930	and time, so using the defaults of five priorities (-2 .. +2) is usually	3011	and time, so using the defaults of five priorities (-2 .. +2) is usually
2931	fine.	3012	fine.
2932		3013
2933	If your embedding app does not need any priorities, defining these both to	3014	If your embedding application does not need any priorities, defining these both to
2934	C<0> will save some memory and cpu.	3015	C<0> will save some memory and CPU.
2935		3016
2936	=item EV_PERIODIC_ENABLE	3017	=item EV_PERIODIC_ENABLE
2937		3018
2938	If undefined or defined to be C<1>, then periodic timers are supported. If	3019	If undefined or defined to be C<1>, then periodic timers are supported. If
2939	defined to be C<0>, then they are not. Disabling them saves a few kB of	3020	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
2966	defined to be C<0>, then they are not.	3047	defined to be C<0>, then they are not.
2967		3048
2968	=item EV_MINIMAL	3049	=item EV_MINIMAL
2969		3050
2970	If you need to shave off some kilobytes of code at the expense of some	3051	If you need to shave off some kilobytes of code at the expense of some
2971	speed, define this symbol to C<1>. Currently only used for gcc to override	3052	speed, define this symbol to C<1>. Currently this is used to override some
2972	some inlining decisions, saves roughly 30% codesize of amd64.	3053	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3054	much smaller 2-heap for timer management over the default 4-heap.
2973		3055
2974	=item EV_PID_HASHSIZE	3056	=item EV_PID_HASHSIZE
2975		3057
2976	C<ev_child> watchers use a small hash table to distribute workload by	3058	C<ev_child> watchers use a small hash table to distribute workload by
2977	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3059	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
…		…
2984	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	3066	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2985	usually more than enough. If you need to manage thousands of C<ev_stat>	3067	usually more than enough. If you need to manage thousands of C<ev_stat>
2986	watchers you might want to increase this value (I<must> be a power of	3068	watchers you might want to increase this value (I<must> be a power of
2987	two).	3069	two).
2988		3070
		3071	=item EV_USE_4HEAP
		3072
		3073	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3074	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3075	to C<1>. The 4-heap uses more complicated (longer) code but has
		3076	noticeably faster performance with many (thousands) of watchers.
		3077
		3078	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3079	(disabled).
		3080
		3081	=item EV_HEAP_CACHE_AT
		3082
		3083	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3084	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3085	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3086	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3087	but avoids random read accesses on heap changes. This improves performance
		3088	noticeably with with many (hundreds) of watchers.
		3089
		3090	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3091	(disabled).
		3092
		3093	=item EV_VERIFY
		3094
		3095	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3096	be done: If set to C<0>, no internal verification code will be compiled
		3097	in. If set to C<1>, then verification code will be compiled in, but not
		3098	called. If set to C<2>, then the internal verification code will be
		3099	called once per loop, which can slow down libev. If set to C<3>, then the
		3100	verification code will be called very frequently, which will slow down
		3101	libev considerably.
		3102
		3103	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3104	C<0.>
		3105
2989	=item EV_COMMON	3106	=item EV_COMMON
2990		3107
2991	By default, all watchers have a C<void *data> member. By redefining	3108	By default, all watchers have a C<void *data> member. By redefining
2992	this macro to a something else you can include more and other types of	3109	this macro to a something else you can include more and other types of
2993	members. You have to define it each time you include one of the files,	3110	members. You have to define it each time you include one of the files,
2994	though, and it must be identical each time.	3111	though, and it must be identical each time.
2995		3112
2996	For example, the perl EV module uses something like this:	3113	For example, the perl EV module uses something like this:
2997		3114
2998	#define EV_COMMON \	3115	#define EV_COMMON \
2999	SV *self; /* contains this struct */ \	3116	SV *self; /* contains this struct */ \
3000	SV *cb_sv, *fh /* note no trailing ";" */	3117	SV *cb_sv, *fh /* note no trailing ";" */
3001		3118
3002	=item EV_CB_DECLARE (type)	3119	=item EV_CB_DECLARE (type)
3003		3120
3004	=item EV_CB_INVOKE (watcher, revents)	3121	=item EV_CB_INVOKE (watcher, revents)
3005		3122
…		…
3012	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3129	avoid the C<struct ev_loop *> as first argument in all cases, or to use
3013	method calls instead of plain function calls in C++.	3130	method calls instead of plain function calls in C++.
3014		3131
3015	=head2 EXPORTED API SYMBOLS	3132	=head2 EXPORTED API SYMBOLS
3016		3133
3017	If you need to re-export the API (e.g. via a dll) and you need a list of	3134	If you need to re-export the API (e.g. via a DLL) and you need a list of
3018	exported symbols, you can use the provided F<Symbol.*> files which list	3135	exported symbols, you can use the provided F<Symbol.*> files which list
3019	all public symbols, one per line:	3136	all public symbols, one per line:
3020		3137
3021	Symbols.ev for libev proper	3138	Symbols.ev for libev proper
3022	Symbols.event for the libevent emulation	3139	Symbols.event for the libevent emulation
3023		3140
3024	This can also be used to rename all public symbols to avoid clashes with	3141	This can also be used to rename all public symbols to avoid clashes with
3025	multiple versions of libev linked together (which is obviously bad in	3142	multiple versions of libev linked together (which is obviously bad in
3026	itself, but sometimes it is inconvinient to avoid this).	3143	itself, but sometimes it is inconvenient to avoid this).
3027		3144
3028	A sed command like this will create wrapper C<#define>'s that you need to	3145	A sed command like this will create wrapper C<#define>'s that you need to
3029	include before including F<ev.h>:	3146	include before including F<ev.h>:
3030		3147
3031	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3148	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3048	file.	3165	file.
3049		3166
3050	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3167	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3051	that everybody includes and which overrides some configure choices:	3168	that everybody includes and which overrides some configure choices:
3052		3169
3053	#define EV_MINIMAL 1	3170	#define EV_MINIMAL 1
3054	#define EV_USE_POLL 0	3171	#define EV_USE_POLL 0
3055	#define EV_MULTIPLICITY 0	3172	#define EV_MULTIPLICITY 0
3056	#define EV_PERIODIC_ENABLE 0	3173	#define EV_PERIODIC_ENABLE 0
3057	#define EV_STAT_ENABLE 0	3174	#define EV_STAT_ENABLE 0
3058	#define EV_FORK_ENABLE 0	3175	#define EV_FORK_ENABLE 0
3059	#define EV_CONFIG_H <config.h>	3176	#define EV_CONFIG_H <config.h>
3060	#define EV_MINPRI 0	3177	#define EV_MINPRI 0
3061	#define EV_MAXPRI 0	3178	#define EV_MAXPRI 0
3062		3179
3063	#include "ev++.h"	3180	#include "ev++.h"
3064		3181
3065	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3182	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3066		3183
3067	#include "ev_cpp.h"	3184	#include "ev_cpp.h"
3068	#include "ev.c"	3185	#include "ev.c"
3069		3186
3070		3187
3071	=head1 THREADS AND COROUTINES	3188	=head1 THREADS AND COROUTINES
3072		3189
3073	=head2 THREADS	3190	=head2 THREADS
3074		3191
3075	Libev itself is completely threadsafe, but it uses no locking. This	3192	Libev itself is completely thread-safe, but it uses no locking. This
3076	means that you can use as many loops as you want in parallel, as long as	3193	means that you can use as many loops as you want in parallel, as long as
3077	only one thread ever calls into one libev function with the same loop	3194	only one thread ever calls into one libev function with the same loop
3078	parameter.	3195	parameter.
3079		3196
3080	Or put differently: calls with different loop parameters can be done in	3197	Or put differently: calls with different loop parameters can be done in
3081	parallel from multiple threads, calls with the same loop parameter must be	3198	parallel from multiple threads, calls with the same loop parameter must be
3082	done serially (but can be done from different threads, as long as only one	3199	done serially (but can be done from different threads, as long as only one
3083	thread ever is inside a call at any point in time, e.g. by using a mutex	3200	thread ever is inside a call at any point in time, e.g. by using a mutex
3084	per loop).	3201	per loop).
3085		3202
3086	If you want to know which design is best for your problem, then I cannot	3203	If you want to know which design (one loop, locking, or multiple loops
3087	help you but by giving some generic advice:	3204	without or something else still) is best for your problem, then I cannot
		3205	help you. I can give some generic advice however:
3088		3206
3089	=over 4	3207	=over 4
3090		3208
3091	=item * most applications have a main thread: use the default libev loop	3209	=item * most applications have a main thread: use the default libev loop
3092	in that thread, or create a seperate thread running only the default loop.	3210	in that thread, or create a separate thread running only the default loop.
3093		3211
3094	This helps integrating other libraries or software modules that use libev	3212	This helps integrating other libraries or software modules that use libev
3095	themselves and don't care/know about threading.	3213	themselves and don't care/know about threading.
3096		3214
3097	=item * one loop per thread is usually a good model.	3215	=item * one loop per thread is usually a good model.
3098		3216
3099	Doing this is almost never wrong, sometimes a better-performance model	3217	Doing this is almost never wrong, sometimes a better-performance model
3100	exists, but it is always a good start.	3218	exists, but it is always a good start.
3101		3219
3102	=item * other models exist, such as the leader/follower pattern, where one	3220	=item * other models exist, such as the leader/follower pattern, where one
3103	loop is handed through multiple threads in a kind of round-robbin fashion.	3221	loop is handed through multiple threads in a kind of round-robin fashion.
3104		3222
3105	Chosing a model is hard - look around, learn, know that usually you cna do	3223	Choosing a model is hard - look around, learn, know that usually you can do
3106	better than you currently do :-)	3224	better than you currently do :-)
3107		3225
3108	=item * often you need to talk to some other thread which blocks in the	3226	=item * often you need to talk to some other thread which blocks in the
3109	event loop - C<ev_async> watchers can be used to wake them up from other	3227	event loop - C<ev_async> watchers can be used to wake them up from other
3110	threads safely (or from signal contexts...).	3228	threads safely (or from signal contexts...).
3111		3229
3112	=back	3230	=back
3113		3231
3114	=head2 COROUTINES	3232	=head2 COROUTINES
3115		3233
3116	Libev is much more accomodating to coroutines ("cooperative threads"):	3234	Libev is much more accommodating to coroutines ("cooperative threads"):
3117	libev fully supports nesting calls to it's functions from different	3235	libev fully supports nesting calls to it's functions from different
3118	coroutines (e.g. you can call C<ev_loop> on the same loop from two	3236	coroutines (e.g. you can call C<ev_loop> on the same loop from two
3119	different coroutines and switch freely between both coroutines running the	3237	different coroutines and switch freely between both coroutines running the
3120	loop, as long as you don't confuse yourself). The only exception is that	3238	loop, as long as you don't confuse yourself). The only exception is that
3121	you must not do this from C<ev_periodic> reschedule callbacks.	3239	you must not do this from C<ev_periodic> reschedule callbacks.
…		…
3162	correct watcher to remove. The lists are usually short (you don't usually	3280	correct watcher to remove. The lists are usually short (you don't usually
3163	have many watchers waiting for the same fd or signal).	3281	have many watchers waiting for the same fd or signal).
3164		3282
3165	=item Finding the next timer in each loop iteration: O(1)	3283	=item Finding the next timer in each loop iteration: O(1)
3166		3284
3167	By virtue of using a binary heap, the next timer is always found at the	3285	By virtue of using a binary or 4-heap, the next timer is always found at a
3168	beginning of the storage array.	3286	fixed position in the storage array.
3169		3287
3170	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3288	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3171		3289
3172	A change means an I/O watcher gets started or stopped, which requires	3290	A change means an I/O watcher gets started or stopped, which requires
3173	libev to recalculate its status (and possibly tell the kernel, depending	3291	libev to recalculate its status (and possibly tell the kernel, depending
3174	on backend and wether C<ev_io_set> was used).	3292	on backend and whether C<ev_io_set> was used).
3175		3293
3176	=item Activating one watcher (putting it into the pending state): O(1)	3294	=item Activating one watcher (putting it into the pending state): O(1)
3177		3295
3178	=item Priority handling: O(number_of_priorities)	3296	=item Priority handling: O(number_of_priorities)
3179		3297
…		…
3186		3304
3187	=item Processing ev_async_send: O(number_of_async_watchers)	3305	=item Processing ev_async_send: O(number_of_async_watchers)
3188		3306
3189	=item Processing signals: O(max_signal_number)	3307	=item Processing signals: O(max_signal_number)
3190		3308
3191	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3309	Sending involves a system call I<iff> there were no other C<ev_async_send>
3192	calls in the current loop iteration. Checking for async and signal events	3310	calls in the current loop iteration. Checking for async and signal events
3193	involves iterating over all running async watchers or all signal numbers.	3311	involves iterating over all running async watchers or all signal numbers.
3194		3312
3195	=back	3313	=back
3196		3314
3197		3315
3198	=head1 Win32 platform limitations and workarounds	3316	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3199		3317
3200	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3318	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3201	requires, and its I/O model is fundamentally incompatible with the POSIX	3319	requires, and its I/O model is fundamentally incompatible with the POSIX
3202	model. Libev still offers limited functionality on this platform in	3320	model. Libev still offers limited functionality on this platform in
3203	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3321	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3204	descriptors. This only applies when using Win32 natively, not when using	3322	descriptors. This only applies when using Win32 natively, not when using
3205	e.g. cygwin.	3323	e.g. cygwin.
3206		3324
		3325	Lifting these limitations would basically require the full
		3326	re-implementation of the I/O system. If you are into these kinds of
		3327	things, then note that glib does exactly that for you in a very portable
		3328	way (note also that glib is the slowest event library known to man).
		3329
3207	There is no supported compilation method available on windows except	3330	There is no supported compilation method available on windows except
3208	embedding it into other applications.	3331	embedding it into other applications.
3209		3332
		3333	Not a libev limitation but worth mentioning: windows apparently doesn't
		3334	accept large writes: instead of resulting in a partial write, windows will
		3335	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3336	so make sure you only write small amounts into your sockets (less than a
		3337	megabyte seems safe, but thsi apparently depends on the amount of memory
		3338	available).
		3339
3210	Due to the many, low, and arbitrary limits on the win32 platform and the	3340	Due to the many, low, and arbitrary limits on the win32 platform and
3211	abysmal performance of winsockets, using a large number of sockets is not	3341	the abysmal performance of winsockets, using a large number of sockets
3212	recommended (and not reasonable). If your program needs to use more than	3342	is not recommended (and not reasonable). If your program needs to use
3213	a hundred or so sockets, then likely it needs to use a totally different	3343	more than a hundred or so sockets, then likely it needs to use a totally
3214	implementation for windows, as libev offers the POSIX model, which cannot	3344	different implementation for windows, as libev offers the POSIX readiness
3215	be implemented efficiently on windows (microsoft monopoly games).	3345	notification model, which cannot be implemented efficiently on windows
		3346	(Microsoft monopoly games).
		3347
		3348	A typical way to use libev under windows is to embed it (see the embedding
		3349	section for details) and use the following F<evwrap.h> header file instead
		3350	of F<ev.h>:
		3351
		3352	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3353	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3354
		3355	#include "ev.h"
		3356
		3357	And compile the following F<evwrap.c> file into your project (make sure
		3358	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3359
		3360	#include "evwrap.h"
		3361	#include "ev.c"
3216		3362
3217	=over 4	3363	=over 4
3218		3364
3219	=item The winsocket select function	3365	=item The winsocket select function
3220		3366
3221	The winsocket C<select> function doesn't follow POSIX in that it requires	3367	The winsocket C<select> function doesn't follow POSIX in that it
3222	socket I<handles> and not socket I<file descriptors>. This makes select	3368	requires socket I<handles> and not socket I<file descriptors> (it is
3223	very inefficient, and also requires a mapping from file descriptors	3369	also extremely buggy). This makes select very inefficient, and also
3224	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,	3370	requires a mapping from file descriptors to socket handles (the Microsoft
3225	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor	3371	C runtime provides the function C<_open_osfhandle> for this). See the
3226	symbols for more info.	3372	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3373	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3227		3374
3228	The configuration for a "naked" win32 using the microsoft runtime	3375	The configuration for a "naked" win32 using the Microsoft runtime
3229	libraries and raw winsocket select is:	3376	libraries and raw winsocket select is:
3230		3377
3231	#define EV_USE_SELECT 1	3378	#define EV_USE_SELECT 1
3232	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3379	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3233		3380
3234	Note that winsockets handling of fd sets is O(n), so you can easily get a	3381	Note that winsockets handling of fd sets is O(n), so you can easily get a
3235	complexity in the O(n²) range when using win32.	3382	complexity in the O(n²) range when using win32.
3236		3383
3237	=item Limited number of file descriptors	3384	=item Limited number of file descriptors
3238		3385
3239	Windows has numerous arbitrary (and low) limits on things. Early versions	3386	Windows has numerous arbitrary (and low) limits on things.
3240	of winsocket's select only supported waiting for a max. of C<64> handles	3387
		3388	Early versions of winsocket's select only supported waiting for a maximum
3241	(probably owning to the fact that all windows kernels can only wait for	3389	of C<64> handles (probably owning to the fact that all windows kernels
3242	C<64> things at the same time internally; microsoft recommends spawning a	3390	can only wait for C<64> things at the same time internally; Microsoft
3243	chain of threads and wait for 63 handles and the previous thread in each).	3391	recommends spawning a chain of threads and wait for 63 handles and the
		3392	previous thread in each. Great).
3244		3393
3245	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3394	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3246	to some high number (e.g. C<2048>) before compiling the winsocket select	3395	to some high number (e.g. C<2048>) before compiling the winsocket select
3247	call (which might be in libev or elsewhere, for example, perl does its own	3396	call (which might be in libev or elsewhere, for example, perl does its own
3248	select emulation on windows).	3397	select emulation on windows).
3249		3398
3250	Another limit is the number of file descriptors in the microsoft runtime	3399	Another limit is the number of file descriptors in the Microsoft runtime
3251	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3400	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3252	or something like this inside microsoft). You can increase this by calling	3401	or something like this inside Microsoft). You can increase this by calling
3253	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3402	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3254	arbitrary limit), but is broken in many versions of the microsoft runtime	3403	arbitrary limit), but is broken in many versions of the Microsoft runtime
3255	libraries.	3404	libraries.
3256		3405
3257	This might get you to about C<512> or C<2048> sockets (depending on	3406	This might get you to about C<512> or C<2048> sockets (depending on
3258	windows version and/or the phase of the moon). To get more, you need to	3407	windows version and/or the phase of the moon). To get more, you need to
3259	wrap all I/O functions and provide your own fd management, but the cost of	3408	wrap all I/O functions and provide your own fd management, but the cost of
3260	calling select (O(n²)) will likely make this unworkable.	3409	calling select (O(n²)) will likely make this unworkable.
3261		3410
3262	=back	3411	=back
3263		3412
3264		3413
		3414	=head1 PORTABILITY REQUIREMENTS
		3415
		3416	In addition to a working ISO-C implementation, libev relies on a few
		3417	additional extensions:
		3418
		3419	=over 4
		3420
		3421	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3422	calling conventions regardless of C<ev_watcher_type *>.
		3423
		3424	Libev assumes not only that all watcher pointers have the same internal
		3425	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3426	assumes that the same (machine) code can be used to call any watcher
		3427	callback: The watcher callbacks have different type signatures, but libev
		3428	calls them using an C<ev_watcher *> internally.
		3429
		3430	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3431
		3432	The type C<sig_atomic_t volatile> (or whatever is defined as
		3433	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3434	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3435	believed to be sufficiently portable.
		3436
		3437	=item C<sigprocmask> must work in a threaded environment
		3438
		3439	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3440	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3441	pthread implementations will either allow C<sigprocmask> in the "main
		3442	thread" or will block signals process-wide, both behaviours would
		3443	be compatible with libev. Interaction between C<sigprocmask> and
		3444	C<pthread_sigmask> could complicate things, however.
		3445
		3446	The most portable way to handle signals is to block signals in all threads
		3447	except the initial one, and run the default loop in the initial thread as
		3448	well.
		3449
		3450	=item C<long> must be large enough for common memory allocation sizes
		3451
		3452	To improve portability and simplify using libev, libev uses C<long>
		3453	internally instead of C<size_t> when allocating its data structures. On
		3454	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3455	is still at least 31 bits everywhere, which is enough for hundreds of
		3456	millions of watchers.
		3457
		3458	=item C<double> must hold a time value in seconds with enough accuracy
		3459
		3460	The type C<double> is used to represent timestamps. It is required to
		3461	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3462	enough for at least into the year 4000. This requirement is fulfilled by
		3463	implementations implementing IEEE 754 (basically all existing ones).
		3464
		3465	=back
		3466
		3467	If you know of other additional requirements drop me a note.
		3468
		3469
		3470	=head1 COMPILER WARNINGS
		3471
		3472	Depending on your compiler and compiler settings, you might get no or a
		3473	lot of warnings when compiling libev code. Some people are apparently
		3474	scared by this.
		3475
		3476	However, these are unavoidable for many reasons. For one, each compiler
		3477	has different warnings, and each user has different tastes regarding
		3478	warning options. "Warn-free" code therefore cannot be a goal except when
		3479	targeting a specific compiler and compiler-version.
		3480
		3481	Another reason is that some compiler warnings require elaborate
		3482	workarounds, or other changes to the code that make it less clear and less
		3483	maintainable.
		3484
		3485	And of course, some compiler warnings are just plain stupid, or simply
		3486	wrong (because they don't actually warn about the condition their message
		3487	seems to warn about).
		3488
		3489	While libev is written to generate as few warnings as possible,
		3490	"warn-free" code is not a goal, and it is recommended not to build libev
		3491	with any compiler warnings enabled unless you are prepared to cope with
		3492	them (e.g. by ignoring them). Remember that warnings are just that:
		3493	warnings, not errors, or proof of bugs.
		3494
		3495
		3496	=head1 VALGRIND
		3497
		3498	Valgrind has a special section here because it is a popular tool that is
		3499	highly useful, but valgrind reports are very hard to interpret.
		3500
		3501	If you think you found a bug (memory leak, uninitialised data access etc.)
		3502	in libev, then check twice: If valgrind reports something like:
		3503
		3504	==2274== definitely lost: 0 bytes in 0 blocks.
		3505	==2274== possibly lost: 0 bytes in 0 blocks.
		3506	==2274== still reachable: 256 bytes in 1 blocks.
		3507
		3508	Then there is no memory leak. Similarly, under some circumstances,
		3509	valgrind might report kernel bugs as if it were a bug in libev, or it
		3510	might be confused (it is a very good tool, but only a tool).
		3511
		3512	If you are unsure about something, feel free to contact the mailing list
		3513	with the full valgrind report and an explanation on why you think this is
		3514	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3515	no bug" answer and take the chance of learning how to interpret valgrind
		3516	properly.
		3517
		3518	If you need, for some reason, empty reports from valgrind for your project
		3519	I suggest using suppression lists.
		3520
		3521
3265	=head1 AUTHOR	3522	=head1 AUTHOR
3266		3523
3267	Marc Lehmann <libev@schmorp.de>.	3524	Marc Lehmann <libev@schmorp.de>.
3268		3525

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