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Revision 1.148 by root, Thu Apr 24 01:42:11 2008 UTC vs.
Revision 1.174 by root, Mon Aug 18 23:23:45 2008 UTC

…		…
2		2
3	libev - a high performance full-featured event loop written in C	3	libev - a high performance full-featured event loop written in C
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
9	=head2 EXAMPLE PROGRAM	9	=head2 EXAMPLE PROGRAM
10		10
11	// a single header file is required	11	// a single header file is required
12	#include <ev.h>	12	#include <ev.h>
13		13
14	// every watcher type has its own typedef'd struct	14	// every watcher type has its own typedef'd struct
15	// with the name ev_<type>	15	// with the name ev_<type>
16	ev_io stdin_watcher;	16	ev_io stdin_watcher;
17	ev_timer timeout_watcher;	17	ev_timer timeout_watcher;
18		18
19	// all watcher callbacks have a similar signature	19	// all watcher callbacks have a similar signature
20	// this callback is called when data is readable on stdin	20	// this callback is called when data is readable on stdin
21	static void	21	static void
22	stdin_cb (EV_P_ struct ev_io *w, int revents)	22	stdin_cb (EV_P_ struct ev_io *w, int revents)
23	{	23	{
24	puts ("stdin ready");	24	puts ("stdin ready");
25	// for one-shot events, one must manually stop the watcher	25	// for one-shot events, one must manually stop the watcher
26	// with its corresponding stop function.	26	// with its corresponding stop function.
27	ev_io_stop (EV_A_ w);	27	ev_io_stop (EV_A_ w);
28		28
29	// this causes all nested ev_loop's to stop iterating	29	// this causes all nested ev_loop's to stop iterating
30	ev_unloop (EV_A_ EVUNLOOP_ALL);	30	ev_unloop (EV_A_ EVUNLOOP_ALL);
31	}	31	}
32		32
33	// another callback, this time for a time-out	33	// another callback, this time for a time-out
34	static void	34	static void
35	timeout_cb (EV_P_ struct ev_timer *w, int revents)	35	timeout_cb (EV_P_ struct ev_timer *w, int revents)
36	{	36	{
37	puts ("timeout");	37	puts ("timeout");
38	// this causes the innermost ev_loop to stop iterating	38	// this causes the innermost ev_loop to stop iterating
39	ev_unloop (EV_A_ EVUNLOOP_ONE);	39	ev_unloop (EV_A_ EVUNLOOP_ONE);
40	}	40	}
41		41
42	int	42	int
43	main (void)	43	main (void)
44	{	44	{
45	// use the default event loop unless you have special needs	45	// use the default event loop unless you have special needs
46	struct ev_loop *loop = ev_default_loop (0);	46	struct ev_loop *loop = ev_default_loop (0);
47		47
48	// initialise an io watcher, then start it	48	// initialise an io watcher, then start it
49	// this one will watch for stdin to become readable	49	// this one will watch for stdin to become readable
50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
51	ev_io_start (loop, &stdin_watcher);	51	ev_io_start (loop, &stdin_watcher);
52		52
53	// initialise a timer watcher, then start it	53	// initialise a timer watcher, then start it
54	// simple non-repeating 5.5 second timeout	54	// simple non-repeating 5.5 second timeout
55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
56	ev_timer_start (loop, &timeout_watcher);	56	ev_timer_start (loop, &timeout_watcher);
57		57
58	// now wait for events to arrive	58	// now wait for events to arrive
59	ev_loop (loop, 0);	59	ev_loop (loop, 0);
60		60
61	// unloop was called, so exit	61	// unloop was called, so exit
62	return 0;	62	return 0;
63	}	63	}
64		64
65	=head1 DESCRIPTION	65	=head1 DESCRIPTION
66		66
67	The newest version of this document is also available as an html-formatted	67	The newest version of this document is also available as an html-formatted
68	web page you might find easier to navigate when reading it for the first	68	web page you might find easier to navigate when reading it for the first
69	time: L<http://cvs.schmorp.de/libev/ev.html>.	69	time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>.
70		70
71	Libev is an event loop: you register interest in certain events (such as a	71	Libev is an event loop: you register interest in certain events (such as a
72	file descriptor being readable or a timeout occurring), and it will manage	72	file descriptor being readable or a timeout occurring), and it will manage
73	these event sources and provide your program with events.	73	these event sources and provide your program with events.
74		74
…		…
113	Libev represents time as a single floating point number, representing the	113	Libev represents time as a single floating point number, representing the
114	(fractional) number of seconds since the (POSIX) epoch (somewhere near	114	(fractional) number of seconds since the (POSIX) epoch (somewhere near
115	the beginning of 1970, details are complicated, don't ask). This type is	115	the beginning of 1970, details are complicated, don't ask). This type is
116	called C<ev_tstamp>, which is what you should use too. It usually aliases	116	called C<ev_tstamp>, which is what you should use too. It usually aliases
117	to the C<double> type in C, and when you need to do any calculations on	117	to the C<double> type in C, and when you need to do any calculations on
118	it, you should treat it as some floatingpoint value. Unlike the name	118	it, you should treat it as some floating point value. Unlike the name
119	component C<stamp> might indicate, it is also used for time differences	119	component C<stamp> might indicate, it is also used for time differences
120	throughout libev.	120	throughout libev.
		121
		122	=head1 ERROR HANDLING
		123
		124	Libev knows three classes of errors: operating system errors, usage errors
		125	and internal errors (bugs).
		126
		127	When libev catches an operating system error it cannot handle (for example
		128	a system call indicating a condition libev cannot fix), it calls the callback
		129	set via C<ev_set_syserr_cb>, which is supposed to fix the problem or
		130	abort. The default is to print a diagnostic message and to call C<abort
		131	()>.
		132
		133	When libev detects a usage error such as a negative timer interval, then
		134	it will print a diagnostic message and abort (via the C<assert> mechanism,
		135	so C<NDEBUG> will disable this checking): these are programming errors in
		136	the libev caller and need to be fixed there.
		137
		138	Libev also has a few internal error-checking C<assert>ions, and also has
		139	extensive consistency checking code. These do not trigger under normal
		140	circumstances, as they indicate either a bug in libev or worse.
		141
121		142
122	=head1 GLOBAL FUNCTIONS	143	=head1 GLOBAL FUNCTIONS
123		144
124	These functions can be called anytime, even before initialising the	145	These functions can be called anytime, even before initialising the
125	library in any way.	146	library in any way.
…		…
134		155
135	=item ev_sleep (ev_tstamp interval)	156	=item ev_sleep (ev_tstamp interval)
136		157
137	Sleep for the given interval: The current thread will be blocked until	158	Sleep for the given interval: The current thread will be blocked until
138	either it is interrupted or the given time interval has passed. Basically	159	either it is interrupted or the given time interval has passed. Basically
139	this is a subsecond-resolution C<sleep ()>.	160	this is a sub-second-resolution C<sleep ()>.
140		161
141	=item int ev_version_major ()	162	=item int ev_version_major ()
142		163
143	=item int ev_version_minor ()	164	=item int ev_version_minor ()
144		165
…		…
157	not a problem.	178	not a problem.
158		179
159	Example: Make sure we haven't accidentally been linked against the wrong	180	Example: Make sure we haven't accidentally been linked against the wrong
160	version.	181	version.
161		182
162	assert (("libev version mismatch",	183	assert (("libev version mismatch",
163	ev_version_major () == EV_VERSION_MAJOR	184	ev_version_major () == EV_VERSION_MAJOR
164	&& ev_version_minor () >= EV_VERSION_MINOR));	185	&& ev_version_minor () >= EV_VERSION_MINOR));
165		186
166	=item unsigned int ev_supported_backends ()	187	=item unsigned int ev_supported_backends ()
167		188
168	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>	189	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>
169	value) compiled into this binary of libev (independent of their	190	value) compiled into this binary of libev (independent of their
…		…
171	a description of the set values.	192	a description of the set values.
172		193
173	Example: make sure we have the epoll method, because yeah this is cool and	194	Example: make sure we have the epoll method, because yeah this is cool and
174	a must have and can we have a torrent of it please!!!11	195	a must have and can we have a torrent of it please!!!11
175		196
176	assert (("sorry, no epoll, no sex",	197	assert (("sorry, no epoll, no sex",
177	ev_supported_backends () & EVBACKEND_EPOLL));	198	ev_supported_backends () & EVBACKEND_EPOLL));
178		199
179	=item unsigned int ev_recommended_backends ()	200	=item unsigned int ev_recommended_backends ()
180		201
181	Return the set of all backends compiled into this binary of libev and also	202	Return the set of all backends compiled into this binary of libev and also
182	recommended for this platform. This set is often smaller than the one	203	recommended for this platform. This set is often smaller than the one
183	returned by C<ev_supported_backends>, as for example kqueue is broken on	204	returned by C<ev_supported_backends>, as for example kqueue is broken on
184	most BSDs and will not be autodetected unless you explicitly request it	205	most BSDs and will not be auto-detected unless you explicitly request it
185	(assuming you know what you are doing). This is the set of backends that	206	(assuming you know what you are doing). This is the set of backends that
186	libev will probe for if you specify no backends explicitly.	207	libev will probe for if you specify no backends explicitly.
187		208
188	=item unsigned int ev_embeddable_backends ()	209	=item unsigned int ev_embeddable_backends ()
189		210
…		…
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
…		…
1092	C<EVBACKEND_POLL>.	1134	C<EVBACKEND_POLL>.
1093		1135
1094	=head3 The special problem of SIGPIPE	1136	=head3 The special problem of SIGPIPE
1095		1137
1096	While not really specific to libev, it is easy to forget about SIGPIPE:	1138	While not really specific to libev, it is easy to forget about SIGPIPE:
1097	when reading from a pipe whose other end has been closed, your program	1139	when writing to a pipe whose other end has been closed, your program gets
1098	gets send a SIGPIPE, which, by default, aborts your program. For most	1140	send a SIGPIPE, which, by default, aborts your program. For most programs
1099	programs this is sensible behaviour, for daemons, this is usually	1141	this is sensible behaviour, for daemons, this is usually undesirable.
1100	undesirable.
1101		1142
1102	So when you encounter spurious, unexplained daemon exits, make sure you	1143	So when you encounter spurious, unexplained daemon exits, make sure you
1103	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1144	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1104	somewhere, as that would have given you a big clue).	1145	somewhere, as that would have given you a big clue).
1105		1146
…		…
1111	=item ev_io_init (ev_io *, callback, int fd, int events)	1152	=item ev_io_init (ev_io *, callback, int fd, int events)
1112		1153
1113	=item ev_io_set (ev_io *, int fd, int events)	1154	=item ev_io_set (ev_io *, int fd, int events)
1114		1155
1115	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1156	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1116	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1157	receive events for and events is either C<EV_READ>, C<EV_WRITE> or
1117	C<EV_READ | EV_WRITE> to receive the given events.	1158	C<EV_READ | EV_WRITE> to receive the given events.
1118		1159
1119	=item int fd [read-only]	1160	=item int fd [read-only]
1120		1161
1121	The file descriptor being watched.	1162	The file descriptor being watched.
…		…
1130		1171
1131	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1172	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1132	readable, but only once. Since it is likely line-buffered, you could	1173	readable, but only once. Since it is likely line-buffered, you could
1133	attempt to read a whole line in the callback.	1174	attempt to read a whole line in the callback.
1134		1175
1135	static void	1176	static void
1136	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1177	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1137	{	1178	{
1138	ev_io_stop (loop, w);	1179	ev_io_stop (loop, w);
1139	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1180	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1140	}	1181	}
1141		1182
1142	...	1183	...
1143	struct ev_loop *loop = ev_default_init (0);	1184	struct ev_loop *loop = ev_default_init (0);
1144	struct ev_io stdin_readable;	1185	struct ev_io stdin_readable;
1145	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1186	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1146	ev_io_start (loop, &stdin_readable);	1187	ev_io_start (loop, &stdin_readable);
1147	ev_loop (loop, 0);	1188	ev_loop (loop, 0);
1148		1189
1149		1190
1150	=head2 C<ev_timer> - relative and optionally repeating timeouts	1191	=head2 C<ev_timer> - relative and optionally repeating timeouts
1151		1192
1152	Timer watchers are simple relative timers that generate an event after a	1193	Timer watchers are simple relative timers that generate an event after a
1153	given time, and optionally repeating in regular intervals after that.	1194	given time, and optionally repeating in regular intervals after that.
1154		1195
1155	The timers are based on real time, that is, if you register an event that	1196	The timers are based on real time, that is, if you register an event that
1156	times out after an hour and you reset your system clock to last years	1197	times out after an hour and you reset your system clock to January last
1157	time, it will still time out after (roughly) and hour. "Roughly" because	1198	year, it will still time out after (roughly) and hour. "Roughly" because
1158	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1199	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1159	monotonic clock option helps a lot here).	1200	monotonic clock option helps a lot here).
1160		1201
1161	The relative timeouts are calculated relative to the C<ev_now ()>	1202	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	1203	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	1205	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:	1206	on the current time, use something like this to adjust for this:
1166		1207
1167	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1208	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1168		1209
1169	The callback is guarenteed to be invoked only when its timeout has passed,	1210	The callback is guaranteed to be invoked only after its timeout has passed,
1170	but if multiple timers become ready during the same loop iteration then	1211	but if multiple timers become ready during the same loop iteration then
1171	order of execution is undefined.	1212	order of execution is undefined.
1172		1213
1173	=head3 Watcher-Specific Functions and Data Members	1214	=head3 Watcher-Specific Functions and Data Members
1174		1215
…		…
1176		1217
1177	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1218	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1178		1219
1179	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1220	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1180		1221
1181	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1222	Configure the timer to trigger after C<after> seconds. If C<repeat>
1182	C<0.>, then it will automatically be stopped. If it is positive, then the	1223	is C<0.>, then it will automatically be stopped once the timeout is
1183	timer will automatically be configured to trigger again C<repeat> seconds	1224	reached. If it is positive, then the timer will automatically be
1184	later, again, and again, until stopped manually.	1225	configured to trigger again C<repeat> seconds later, again, and again,
		1226	until stopped manually.
1185		1227
1186	The timer itself will do a best-effort at avoiding drift, that is, if you	1228	The timer itself will do a best-effort at avoiding drift, that is, if
1187	configure a timer to trigger every 10 seconds, then it will trigger at	1229	you configure a timer to trigger every 10 seconds, then it will normally
1188	exactly 10 second intervals. If, however, your program cannot keep up with	1230	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	1231	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.	1232	do stuff) the timer will not fire more than once per event loop iteration.
1191		1233
1192	=item ev_timer_again (loop, ev_timer *)	1234	=item ev_timer_again (loop, ev_timer *)
1193		1235
1194	This will act as if the timer timed out and restart it again if it is	1236	This will act as if the timer timed out and restart it again if it is
1195	repeating. The exact semantics are:	1237	repeating. The exact semantics are:
1196		1238
1197	If the timer is pending, its pending status is cleared.	1239	If the timer is pending, its pending status is cleared.
1198		1240
1199	If the timer is started but nonrepeating, stop it (as if it timed out).	1241	If the timer is started but non-repeating, stop it (as if it timed out).
1200		1242
1201	If the timer is repeating, either start it if necessary (with the	1243	If the timer is repeating, either start it if necessary (with the
1202	C<repeat> value), or reset the running timer to the C<repeat> value.	1244	C<repeat> value), or reset the running timer to the C<repeat> value.
1203		1245
1204	This sounds a bit complicated, but here is a useful and typical	1246	This sounds a bit complicated, but here is a useful and typical
1205	example: Imagine you have a tcp connection and you want a so-called idle	1247	example: Imagine you have a TCP connection and you want a so-called idle
1206	timeout, that is, you want to be called when there have been, say, 60	1248	timeout, that is, you want to be called when there have been, say, 60
1207	seconds of inactivity on the socket. The easiest way to do this is to	1249	seconds of inactivity on the socket. The easiest way to do this is to
1208	configure an C<ev_timer> with a C<repeat> value of C<60> and then call	1250	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1209	C<ev_timer_again> each time you successfully read or write some data. If	1251	C<ev_timer_again> each time you successfully read or write some data. If
1210	you go into an idle state where you do not expect data to travel on the	1252	you go into an idle state where you do not expect data to travel on the
…		…
1236		1278
1237	=head3 Examples	1279	=head3 Examples
1238		1280
1239	Example: Create a timer that fires after 60 seconds.	1281	Example: Create a timer that fires after 60 seconds.
1240		1282
1241	static void	1283	static void
1242	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1284	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1243	{	1285	{
1244	.. one minute over, w is actually stopped right here	1286	.. one minute over, w is actually stopped right here
1245	}	1287	}
1246		1288
1247	struct ev_timer mytimer;	1289	struct ev_timer mytimer;
1248	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1290	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1249	ev_timer_start (loop, &mytimer);	1291	ev_timer_start (loop, &mytimer);
1250		1292
1251	Example: Create a timeout timer that times out after 10 seconds of	1293	Example: Create a timeout timer that times out after 10 seconds of
1252	inactivity.	1294	inactivity.
1253		1295
1254	static void	1296	static void
1255	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1297	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1256	{	1298	{
1257	.. ten seconds without any activity	1299	.. ten seconds without any activity
1258	}	1300	}
1259		1301
1260	struct ev_timer mytimer;	1302	struct ev_timer mytimer;
1261	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1303	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1262	ev_timer_again (&mytimer); /* start timer */	1304	ev_timer_again (&mytimer); /* start timer */
1263	ev_loop (loop, 0);	1305	ev_loop (loop, 0);
1264		1306
1265	// and in some piece of code that gets executed on any "activity":	1307	// and in some piece of code that gets executed on any "activity":
1266	// reset the timeout to start ticking again at 10 seconds	1308	// reset the timeout to start ticking again at 10 seconds
1267	ev_timer_again (&mytimer);	1309	ev_timer_again (&mytimer);
1268		1310
1269		1311
1270	=head2 C<ev_periodic> - to cron or not to cron?	1312	=head2 C<ev_periodic> - to cron or not to cron?
1271		1313
1272	Periodic watchers are also timers of a kind, but they are very versatile	1314	Periodic watchers are also timers of a kind, but they are very versatile
1273	(and unfortunately a bit complex).	1315	(and unfortunately a bit complex).
1274		1316
1275	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1317	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
1276	but on wallclock time (absolute time). You can tell a periodic watcher	1318	but on wall clock time (absolute time). You can tell a periodic watcher
1277	to trigger "at" some specific point in time. For example, if you tell a	1319	to trigger after some specific point in time. For example, if you tell a
1278	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1320	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()
1279	+ 10.>) and then reset your system clock to the last year, then it will	1321	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1322	clock to January of the previous year, then it will take more than year
1280	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1323	to trigger the event (unlike an C<ev_timer>, which would still trigger
1281	roughly 10 seconds later).	1324	roughly 10 seconds later as it uses a relative timeout).
1282		1325
1283	They can also be used to implement vastly more complex timers, such as	1326	C<ev_periodic>s can also be used to implement vastly more complex timers,
1284	triggering an event on each midnight, local time or other, complicated,	1327	such as triggering an event on each "midnight, local time", or other
1285	rules.	1328	complicated, rules.
1286		1329
1287	As with timers, the callback is guarenteed to be invoked only when the	1330	As with timers, the callback is guaranteed to be invoked only when the
1288	time (C<at>) has been passed, but if multiple periodic timers become ready	1331	time (C<at>) has passed, but if multiple periodic timers become ready
1289	during the same loop iteration then order of execution is undefined.	1332	during the same loop iteration then order of execution is undefined.
1290		1333
1291	=head3 Watcher-Specific Functions and Data Members	1334	=head3 Watcher-Specific Functions and Data Members
1292		1335
1293	=over 4	1336	=over 4
…		…
1301		1344
1302	=over 4	1345	=over 4
1303		1346
1304	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1347	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1305		1348
1306	In this configuration the watcher triggers an event at the wallclock time	1349	In this configuration the watcher triggers an event after the wall clock
1307	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1350	time C<at> has passed and doesn't repeat. It will not adjust when a time
1308	that is, if it is to be run at January 1st 2011 then it will run when the	1351	jump occurs, that is, if it is to be run at January 1st 2011 then it will
1309	system time reaches or surpasses this time.	1352	run when the system time reaches or surpasses this time.
1310		1353
1311	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1354	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1312		1355
1313	In this mode the watcher will always be scheduled to time out at the next	1356	In this mode the watcher will always be scheduled to time out at the next
1314	C<at + N * interval> time (for some integer N, which can also be negative)	1357	C<at + N * interval> time (for some integer N, which can also be negative)
1315	and then repeat, regardless of any time jumps.	1358	and then repeat, regardless of any time jumps.
1316		1359
1317	This can be used to create timers that do not drift with respect to system	1360	This can be used to create timers that do not drift with respect to system
1318	time:	1361	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1362	the hour:
1319		1363
1320	ev_periodic_set (&periodic, 0., 3600., 0);	1364	ev_periodic_set (&periodic, 0., 3600., 0);
1321		1365
1322	This doesn't mean there will always be 3600 seconds in between triggers,	1366	This doesn't mean there will always be 3600 seconds in between triggers,
1323	but only that the the callback will be called when the system time shows a	1367	but only that the callback will be called when the system time shows a
1324	full hour (UTC), or more correctly, when the system time is evenly divisible	1368	full hour (UTC), or more correctly, when the system time is evenly divisible
1325	by 3600.	1369	by 3600.
1326		1370
1327	Another way to think about it (for the mathematically inclined) is that	1371	Another way to think about it (for the mathematically inclined) is that
1328	C<ev_periodic> will try to run the callback in this mode at the next possible	1372	C<ev_periodic> will try to run the callback in this mode at the next possible
1329	time where C<time = at (mod interval)>, regardless of any time jumps.	1373	time where C<time = at (mod interval)>, regardless of any time jumps.
1330		1374
1331	For numerical stability it is preferable that the C<at> value is near	1375	For numerical stability it is preferable that the C<at> value is near
1332	C<ev_now ()> (the current time), but there is no range requirement for	1376	C<ev_now ()> (the current time), but there is no range requirement for
1333	this value.	1377	this value, and in fact is often specified as zero.
		1378
		1379	Note also that there is an upper limit to how often a timer can fire (CPU
		1380	speed for example), so if C<interval> is very small then timing stability
		1381	will of course deteriorate. Libev itself tries to be exact to be about one
		1382	millisecond (if the OS supports it and the machine is fast enough).
1334		1383
1335	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1384	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1336		1385
1337	In this mode the values for C<interval> and C<at> are both being	1386	In this mode the values for C<interval> and C<at> are both being
1338	ignored. Instead, each time the periodic watcher gets scheduled, the	1387	ignored. Instead, each time the periodic watcher gets scheduled, the
1339	reschedule callback will be called with the watcher as first, and the	1388	reschedule callback will be called with the watcher as first, and the
1340	current time as second argument.	1389	current time as second argument.
1341		1390
1342	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1391	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1343	ever, or make any event loop modifications>. If you need to stop it,	1392	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		1393
		1394	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1395	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1396	only event loop modification you are allowed to do).
		1397
1347	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1398	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1348	ev_tstamp now)>, e.g.:	1399	*w, ev_tstamp now)>, e.g.:
1349		1400
1350	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1401	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1351	{	1402	{
1352	return now + 60.;	1403	return now + 60.;
1353	}	1404	}
…		…
1355	It must return the next time to trigger, based on the passed time value	1406	It must return the next time to trigger, based on the passed time value
1356	(that is, the lowest time value larger than to the second argument). It	1407	(that is, the lowest time value larger than to the second argument). It
1357	will usually be called just before the callback will be triggered, but	1408	will usually be called just before the callback will be triggered, but
1358	might be called at other times, too.	1409	might be called at other times, too.
1359		1410
1360	NOTE: I<< This callback must always return a time that is later than the	1411	NOTE: I<< This callback must always return a time that is higher than or
1361	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.	1412	equal to the passed C<now> value >>.
1362		1413
1363	This can be used to create very complex timers, such as a timer that	1414	This can be used to create very complex timers, such as a timer that
1364	triggers on each midnight, local time. To do this, you would calculate the	1415	triggers on "next midnight, local time". To do this, you would calculate the
1365	next midnight after C<now> and return the timestamp value for this. How	1416	next midnight after C<now> and return the timestamp value for this. How
1366	you do this is, again, up to you (but it is not trivial, which is the main	1417	you do this is, again, up to you (but it is not trivial, which is the main
1367	reason I omitted it as an example).	1418	reason I omitted it as an example).
1368		1419
1369	=back	1420	=back
…		…
1373	Simply stops and restarts the periodic watcher again. This is only useful	1424	Simply stops and restarts the periodic watcher again. This is only useful
1374	when you changed some parameters or the reschedule callback would return	1425	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	1426	a different time than the last time it was called (e.g. in a crond like
1376	program when the crontabs have changed).	1427	program when the crontabs have changed).
1377		1428
		1429	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1430
		1431	When active, returns the absolute time that the watcher is supposed to
		1432	trigger next.
		1433
1378	=item ev_tstamp offset [read-write]	1434	=item ev_tstamp offset [read-write]
1379		1435
1380	When repeating, this contains the offset value, otherwise this is the	1436	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>).	1437	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1382		1438
…		…
1393		1449
1394	The current reschedule callback, or C<0>, if this functionality is	1450	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	1451	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.	1452	the periodic timer fires or C<ev_periodic_again> is being called.
1397		1453
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	1454	=back
1404		1455
1405	=head3 Examples	1456	=head3 Examples
1406		1457
1407	Example: Call a callback every hour, or, more precisely, whenever the	1458	Example: Call a callback every hour, or, more precisely, whenever the
1408	system clock is divisible by 3600. The callback invocation times have	1459	system clock is divisible by 3600. The callback invocation times have
1409	potentially a lot of jittering, but good long-term stability.	1460	potentially a lot of jitter, but good long-term stability.
1410		1461
1411	static void	1462	static void
1412	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1463	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1413	{	1464	{
1414	... its now a full hour (UTC, or TAI or whatever your clock follows)	1465	... its now a full hour (UTC, or TAI or whatever your clock follows)
1415	}	1466	}
1416		1467
1417	struct ev_periodic hourly_tick;	1468	struct ev_periodic hourly_tick;
1418	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1469	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1419	ev_periodic_start (loop, &hourly_tick);	1470	ev_periodic_start (loop, &hourly_tick);
1420		1471
1421	Example: The same as above, but use a reschedule callback to do it:	1472	Example: The same as above, but use a reschedule callback to do it:
1422		1473
1423	#include <math.h>	1474	#include <math.h>
1424		1475
1425	static ev_tstamp	1476	static ev_tstamp
1426	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1477	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1427	{	1478	{
1428	return fmod (now, 3600.) + 3600.;	1479	return fmod (now, 3600.) + 3600.;
1429	}	1480	}
1430		1481
1431	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1482	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1432		1483
1433	Example: Call a callback every hour, starting now:	1484	Example: Call a callback every hour, starting now:
1434		1485
1435	struct ev_periodic hourly_tick;	1486	struct ev_periodic hourly_tick;
1436	ev_periodic_init (&hourly_tick, clock_cb,	1487	ev_periodic_init (&hourly_tick, clock_cb,
1437	fmod (ev_now (loop), 3600.), 3600., 0);	1488	fmod (ev_now (loop), 3600.), 3600., 0);
1438	ev_periodic_start (loop, &hourly_tick);	1489	ev_periodic_start (loop, &hourly_tick);
1439		1490
1440		1491
1441	=head2 C<ev_signal> - signal me when a signal gets signalled!	1492	=head2 C<ev_signal> - signal me when a signal gets signalled!
1442		1493
1443	Signal watchers will trigger an event when the process receives a specific	1494	Signal watchers will trigger an event when the process receives a specific
…		…
1451	as you don't register any with libev). Similarly, when the last signal	1502	as you don't register any with libev). Similarly, when the last signal
1452	watcher for a signal is stopped libev will reset the signal handler to	1503	watcher for a signal is stopped libev will reset the signal handler to
1453	SIG_DFL (regardless of what it was set to before).	1504	SIG_DFL (regardless of what it was set to before).
1454		1505
1455	If possible and supported, libev will install its handlers with	1506	If possible and supported, libev will install its handlers with
1456	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1507	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1457	interrupted. If you have a problem with syscalls getting interrupted by	1508	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	1509	signals you can block all signals in an C<ev_check> watcher and unblock
1459	them in an C<ev_prepare> watcher.	1510	them in an C<ev_prepare> watcher.
1460		1511
1461	=head3 Watcher-Specific Functions and Data Members	1512	=head3 Watcher-Specific Functions and Data Members
1462		1513
…		…
1477		1528
1478	=head3 Examples	1529	=head3 Examples
1479		1530
1480	Example: Try to exit cleanly on SIGINT and SIGTERM.	1531	Example: Try to exit cleanly on SIGINT and SIGTERM.
1481		1532
1482	static void	1533	static void
1483	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1534	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1484	{	1535	{
1485	ev_unloop (loop, EVUNLOOP_ALL);	1536	ev_unloop (loop, EVUNLOOP_ALL);
1486	}	1537	}
1487		1538
1488	struct ev_signal signal_watcher;	1539	struct ev_signal signal_watcher;
1489	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1540	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1490	ev_signal_start (loop, &sigint_cb);	1541	ev_signal_start (loop, &sigint_cb);
1491		1542
1492		1543
1493	=head2 C<ev_child> - watch out for process status changes	1544	=head2 C<ev_child> - watch out for process status changes
1494		1545
1495	Child watchers trigger when your process receives a SIGCHLD in response to	1546	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1497	is permissible to install a child watcher I<after> the child has been	1548	is permissible to install a child watcher I<after> the child has been
1498	forked (which implies it might have already exited), as long as the event	1549	forked (which implies it might have already exited), as long as the event
1499	loop isn't entered (or is continued from a watcher).	1550	loop isn't entered (or is continued from a watcher).
1500		1551
1501	Only the default event loop is capable of handling signals, and therefore	1552	Only the default event loop is capable of handling signals, and therefore
1502	you can only rgeister child watchers in the default event loop.	1553	you can only register child watchers in the default event loop.
1503		1554
1504	=head3 Process Interaction	1555	=head3 Process Interaction
1505		1556
1506	Libev grabs C<SIGCHLD> as soon as the default event loop is	1557	Libev grabs C<SIGCHLD> as soon as the default event loop is
1507	initialised. This is necessary to guarantee proper behaviour even if	1558	initialised. This is necessary to guarantee proper behaviour even if
1508	the first child watcher is started after the child exits. The occurance	1559	the first child watcher is started after the child exits. The occurrence
1509	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1560	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1510	synchronously as part of the event loop processing. Libev always reaps all	1561	synchronously as part of the event loop processing. Libev always reaps all
1511	children, even ones not watched.	1562	children, even ones not watched.
1512		1563
1513	=head3 Overriding the Built-In Processing	1564	=head3 Overriding the Built-In Processing
…		…
1517	handler, you can override it easily by installing your own handler for	1568	handler, you can override it easily by installing your own handler for
1518	C<SIGCHLD> after initialising the default loop, and making sure the	1569	C<SIGCHLD> after initialising the default loop, and making sure the
1519	default loop never gets destroyed. You are encouraged, however, to use an	1570	default loop never gets destroyed. You are encouraged, however, to use an
1520	event-based approach to child reaping and thus use libev's support for	1571	event-based approach to child reaping and thus use libev's support for
1521	that, so other libev users can use C<ev_child> watchers freely.	1572	that, so other libev users can use C<ev_child> watchers freely.
		1573
		1574	=head3 Stopping the Child Watcher
		1575
		1576	Currently, the child watcher never gets stopped, even when the
		1577	child terminates, so normally one needs to stop the watcher in the
		1578	callback. Future versions of libev might stop the watcher automatically
		1579	when a child exit is detected.
1522		1580
1523	=head3 Watcher-Specific Functions and Data Members	1581	=head3 Watcher-Specific Functions and Data Members
1524		1582
1525	=over 4	1583	=over 4
1526		1584
…		…
1555	=head3 Examples	1613	=head3 Examples
1556		1614
1557	Example: C<fork()> a new process and install a child handler to wait for	1615	Example: C<fork()> a new process and install a child handler to wait for
1558	its completion.	1616	its completion.
1559		1617
1560	ev_child cw;	1618	ev_child cw;
1561		1619
1562	static void	1620	static void
1563	child_cb (EV_P_ struct ev_child *w, int revents)	1621	child_cb (EV_P_ struct ev_child *w, int revents)
1564	{	1622	{
1565	ev_child_stop (EV_A_ w);	1623	ev_child_stop (EV_A_ w);
1566	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1624	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1567	}	1625	}
1568		1626
1569	pid_t pid = fork ();	1627	pid_t pid = fork ();
1570		1628
1571	if (pid < 0)	1629	if (pid < 0)
1572	// error	1630	// error
1573	else if (pid == 0)	1631	else if (pid == 0)
1574	{	1632	{
1575	// the forked child executes here	1633	// the forked child executes here
1576	exit (1);	1634	exit (1);
1577	}	1635	}
1578	else	1636	else
1579	{	1637	{
1580	ev_child_init (&cw, child_cb, pid, 0);	1638	ev_child_init (&cw, child_cb, pid, 0);
1581	ev_child_start (EV_DEFAULT_ &cw);	1639	ev_child_start (EV_DEFAULT_ &cw);
1582	}	1640	}
1583		1641
1584		1642
1585	=head2 C<ev_stat> - did the file attributes just change?	1643	=head2 C<ev_stat> - did the file attributes just change?
1586		1644
1587	This watches a filesystem path for attribute changes. That is, it calls	1645	This watches a file system path for attribute changes. That is, it calls
1588	C<stat> regularly (or when the OS says it changed) and sees if it changed	1646	C<stat> regularly (or when the OS says it changed) and sees if it changed
1589	compared to the last time, invoking the callback if it did.	1647	compared to the last time, invoking the callback if it did.
1590		1648
1591	The path does not need to exist: changing from "path exists" to "path does	1649	The path does not need to exist: changing from "path exists" to "path does
1592	not exist" is a status change like any other. The condition "path does	1650	not exist" is a status change like any other. The condition "path does
…		…
1610	as even with OS-supported change notifications, this can be	1668	as even with OS-supported change notifications, this can be
1611	resource-intensive.	1669	resource-intensive.
1612		1670
1613	At the time of this writing, only the Linux inotify interface is	1671	At the time of this writing, only the Linux inotify interface is
1614	implemented (implementing kqueue support is left as an exercise for the	1672	implemented (implementing kqueue support is left as an exercise for the
		1673	reader, note, however, that the author sees no way of implementing ev_stat
1615	reader). Inotify will be used to give hints only and should not change the	1674	semantics with kqueue). Inotify will be used to give hints only and should
1616	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1675	not change the semantics of C<ev_stat> watchers, which means that libev
1617	to fall back to regular polling again even with inotify, but changes are	1676	sometimes needs to fall back to regular polling again even with inotify,
1618	usually detected immediately, and if the file exists there will be no	1677	but changes are usually detected immediately, and if the file exists there
1619	polling.	1678	will be no polling.
1620		1679
1621	=head3 ABI Issues (Largefile Support)	1680	=head3 ABI Issues (Largefile Support)
1622		1681
1623	Libev by default (unless the user overrides this) uses the default	1682	Libev by default (unless the user overrides this) uses the default
1624	compilation environment, which means that on systems with optionally	1683	compilation environment, which means that on systems with large file
1625	disabled large file support, you get the 32 bit version of the stat	1684	support disabled by default, you get the 32 bit version of the stat
1626	structure. When using the library from programs that change the ABI to	1685	structure. When using the library from programs that change the ABI to
1627	use 64 bit file offsets the programs will fail. In that case you have to	1686	use 64 bit file offsets the programs will fail. In that case you have to
1628	compile libev with the same flags to get binary compatibility. This is	1687	compile libev with the same flags to get binary compatibility. This is
1629	obviously the case with any flags that change the ABI, but the problem is	1688	obviously the case with any flags that change the ABI, but the problem is
1630	most noticably with ev_stat and largefile support.	1689	most noticeably disabled with ev_stat and large file support.
		1690
		1691	The solution for this is to lobby your distribution maker to make large
		1692	file interfaces available by default (as e.g. FreeBSD does) and not
		1693	optional. Libev cannot simply switch on large file support because it has
		1694	to exchange stat structures with application programs compiled using the
		1695	default compilation environment.
1631		1696
1632	=head3 Inotify	1697	=head3 Inotify
1633		1698
1634	When C<inotify (7)> support has been compiled into libev (generally only	1699	When C<inotify (7)> support has been compiled into libev (generally only
1635	available on Linux) and present at runtime, it will be used to speed up	1700	available on Linux) and present at runtime, it will be used to speed up
…		…
1645	implement this functionality, due to the requirement of having a file	1710	implement this functionality, due to the requirement of having a file
1646	descriptor open on the object at all times).	1711	descriptor open on the object at all times).
1647		1712
1648	=head3 The special problem of stat time resolution	1713	=head3 The special problem of stat time resolution
1649		1714
1650	The C<stat ()> syscall only supports full-second resolution portably, and	1715	The C<stat ()> system call only supports full-second resolution portably, and
1651	even on systems where the resolution is higher, many filesystems still	1716	even on systems where the resolution is higher, many file systems still
1652	only support whole seconds.	1717	only support whole seconds.
1653		1718
1654	That means that, if the time is the only thing that changes, you might	1719	That means that, if the time is the only thing that changes, you can
1655	miss updates: on the first update, C<ev_stat> detects a change and calls	1720	easily miss updates: on the first update, C<ev_stat> detects a change and
1656	your callback, which does something. When there is another update within	1721	calls your callback, which does something. When there is another update
1657	the same second, C<ev_stat> will be unable to detect it.	1722	within the same second, C<ev_stat> will be unable to detect it as the stat
		1723	data does not change.
1658		1724
1659	The solution to this is to delay acting on a change for a second (or till	1725	The solution to this is to delay acting on a change for slightly more
1660	the next second boundary), using a roughly one-second delay C<ev_timer>	1726	than a second (or till slightly after the next full second boundary), using
1661	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>	1727	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);
1662	is added to work around small timing inconsistencies of some operating	1728	ev_timer_again (loop, w)>).
1663	systems.	1729
		1730	The C<.02> offset is added to work around small timing inconsistencies
		1731	of some operating systems (where the second counter of the current time
		1732	might be be delayed. One such system is the Linux kernel, where a call to
		1733	C<gettimeofday> might return a timestamp with a full second later than
		1734	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1735	update file times then there will be a small window where the kernel uses
		1736	the previous second to update file times but libev might already execute
		1737	the timer callback).
1664		1738
1665	=head3 Watcher-Specific Functions and Data Members	1739	=head3 Watcher-Specific Functions and Data Members
1666		1740
1667	=over 4	1741	=over 4
1668		1742
…		…
1674	C<path>. The C<interval> is a hint on how quickly a change is expected to	1748	C<path>. The C<interval> is a hint on how quickly a change is expected to
1675	be detected and should normally be specified as C<0> to let libev choose	1749	be detected and should normally be specified as C<0> to let libev choose
1676	a suitable value. The memory pointed to by C<path> must point to the same	1750	a suitable value. The memory pointed to by C<path> must point to the same
1677	path for as long as the watcher is active.	1751	path for as long as the watcher is active.
1678		1752
1679	The callback will be receive C<EV_STAT> when a change was detected,	1753	The callback will receive C<EV_STAT> when a change was detected, relative
1680	relative to the attributes at the time the watcher was started (or the	1754	to the attributes at the time the watcher was started (or the last change
1681	last change was detected).	1755	was detected).
1682		1756
1683	=item ev_stat_stat (loop, ev_stat *)	1757	=item ev_stat_stat (loop, ev_stat *)
1684		1758
1685	Updates the stat buffer immediately with new values. If you change the	1759	Updates the stat buffer immediately with new values. If you change the
1686	watched path in your callback, you could call this fucntion to avoid	1760	watched path in your callback, you could call this function to avoid
1687	detecting this change (while introducing a race condition). Can also be	1761	detecting this change (while introducing a race condition if you are not
1688	useful simply to find out the new values.	1762	the only one changing the path). Can also be useful simply to find out the
		1763	new values.
1689		1764
1690	=item ev_statdata attr [read-only]	1765	=item ev_statdata attr [read-only]
1691		1766
1692	The most-recently detected attributes of the file. Although the type is of	1767	The most-recently detected attributes of the file. Although the type is
1693	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types	1768	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
1694	suitable for your system. If the C<st_nlink> member is C<0>, then there	1769	suitable for your system, but you can only rely on the POSIX-standardised
		1770	members to be present. If the C<st_nlink> member is C<0>, then there was
1695	was some error while C<stat>ing the file.	1771	some error while C<stat>ing the file.
1696		1772
1697	=item ev_statdata prev [read-only]	1773	=item ev_statdata prev [read-only]
1698		1774
1699	The previous attributes of the file. The callback gets invoked whenever	1775	The previous attributes of the file. The callback gets invoked whenever
1700	C<prev> != C<attr>.	1776	C<prev> != C<attr>, or, more precisely, one or more of these members
		1777	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1778	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1701		1779
1702	=item ev_tstamp interval [read-only]	1780	=item ev_tstamp interval [read-only]
1703		1781
1704	The specified interval.	1782	The specified interval.
1705		1783
1706	=item const char *path [read-only]	1784	=item const char *path [read-only]
1707		1785
1708	The filesystem path that is being watched.	1786	The file system path that is being watched.
1709		1787
1710	=back	1788	=back
1711		1789
1712	=head3 Examples	1790	=head3 Examples
1713		1791
1714	Example: Watch C</etc/passwd> for attribute changes.	1792	Example: Watch C</etc/passwd> for attribute changes.
1715		1793
1716	static void	1794	static void
1717	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1795	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1718	{	1796	{
1719	/* /etc/passwd changed in some way */	1797	/* /etc/passwd changed in some way */
1720	if (w->attr.st_nlink)	1798	if (w->attr.st_nlink)
1721	{	1799	{
1722	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1800	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1723	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1801	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1724	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1802	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1725	}	1803	}
1726	else	1804	else
1727	/* you shalt not abuse printf for puts */	1805	/* you shalt not abuse printf for puts */
1728	puts ("wow, /etc/passwd is not there, expect problems. "	1806	puts ("wow, /etc/passwd is not there, expect problems. "
1729	"if this is windows, they already arrived\n");	1807	"if this is windows, they already arrived\n");
1730	}	1808	}
1731		1809
1732	...	1810	...
1733	ev_stat passwd;	1811	ev_stat passwd;
1734		1812
1735	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1813	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1736	ev_stat_start (loop, &passwd);	1814	ev_stat_start (loop, &passwd);
1737		1815
1738	Example: Like above, but additionally use a one-second delay so we do not	1816	Example: Like above, but additionally use a one-second delay so we do not
1739	miss updates (however, frequent updates will delay processing, too, so	1817	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	1818	one might do the work both on C<ev_stat> callback invocation I<and> on
1741	C<ev_timer> callback invocation).	1819	C<ev_timer> callback invocation).
1742		1820
1743	static ev_stat passwd;	1821	static ev_stat passwd;
1744	static ev_timer timer;	1822	static ev_timer timer;
1745		1823
1746	static void	1824	static void
1747	timer_cb (EV_P_ ev_timer *w, int revents)	1825	timer_cb (EV_P_ ev_timer *w, int revents)
1748	{	1826	{
1749	ev_timer_stop (EV_A_ w);	1827	ev_timer_stop (EV_A_ w);
1750		1828
1751	/* now it's one second after the most recent passwd change */	1829	/* now it's one second after the most recent passwd change */
1752	}	1830	}
1753		1831
1754	static void	1832	static void
1755	stat_cb (EV_P_ ev_stat *w, int revents)	1833	stat_cb (EV_P_ ev_stat *w, int revents)
1756	{	1834	{
1757	/* reset the one-second timer */	1835	/* reset the one-second timer */
1758	ev_timer_again (EV_A_ &timer);	1836	ev_timer_again (EV_A_ &timer);
1759	}	1837	}
1760		1838
1761	...	1839	...
1762	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1840	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1763	ev_stat_start (loop, &passwd);	1841	ev_stat_start (loop, &passwd);
1764	ev_timer_init (&timer, timer_cb, 0., 1.01);	1842	ev_timer_init (&timer, timer_cb, 0., 1.02);
1765		1843
1766		1844
1767	=head2 C<ev_idle> - when you've got nothing better to do...	1845	=head2 C<ev_idle> - when you've got nothing better to do...
1768		1846
1769	Idle watchers trigger events when no other events of the same or higher	1847	Idle watchers trigger events when no other events of the same or higher
…		…
1800	=head3 Examples	1878	=head3 Examples
1801		1879
1802	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1880	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1803	callback, free it. Also, use no error checking, as usual.	1881	callback, free it. Also, use no error checking, as usual.
1804		1882
1805	static void	1883	static void
1806	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1884	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1807	{	1885	{
1808	free (w);	1886	free (w);
1809	// now do something you wanted to do when the program has	1887	// now do something you wanted to do when the program has
1810	// no longer anything immediate to do.	1888	// no longer anything immediate to do.
1811	}	1889	}
1812		1890
1813	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1891	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1814	ev_idle_init (idle_watcher, idle_cb);	1892	ev_idle_init (idle_watcher, idle_cb);
1815	ev_idle_start (loop, idle_cb);	1893	ev_idle_start (loop, idle_cb);
1816		1894
1817		1895
1818	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1896	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1819		1897
1820	Prepare and check watchers are usually (but not always) used in tandem:	1898	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1839		1917
1840	This is done by examining in each prepare call which file descriptors need	1918	This is done by examining in each prepare call which file descriptors need
1841	to be watched by the other library, registering C<ev_io> watchers for	1919	to be watched by the other library, registering C<ev_io> watchers for
1842	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1920	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1843	provide just this functionality). Then, in the check watcher you check for	1921	provide just this functionality). Then, in the check watcher you check for
1844	any events that occured (by checking the pending status of all watchers	1922	any events that occurred (by checking the pending status of all watchers
1845	and stopping them) and call back into the library. The I/O and timer	1923	and stopping them) and call back into the library. The I/O and timer
1846	callbacks will never actually be called (but must be valid nevertheless,	1924	callbacks will never actually be called (but must be valid nevertheless,
1847	because you never know, you know?).	1925	because you never know, you know?).
1848		1926
1849	As another example, the Perl Coro module uses these hooks to integrate	1927	As another example, the Perl Coro module uses these hooks to integrate
…		…
1857		1935
1858	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1936	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
1859	priority, to ensure that they are being run before any other watchers	1937	priority, to ensure that they are being run before any other watchers
1860	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,	1938	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
1861	too) should not activate ("feed") events into libev. While libev fully	1939	too) should not activate ("feed") events into libev. While libev fully
1862	supports this, they will be called before other C<ev_check> watchers	1940	supports this, they might get executed before other C<ev_check> watchers
1863	did their job. As C<ev_check> watchers are often used to embed other	1941	did their job. As C<ev_check> watchers are often used to embed other
1864	(non-libev) event loops those other event loops might be in an unusable	1942	(non-libev) event loops those other event loops might be in an unusable
1865	state until their C<ev_check> watcher ran (always remind yourself to	1943	state until their C<ev_check> watcher ran (always remind yourself to
1866	coexist peacefully with others).	1944	coexist peacefully with others).
1867		1945
…		…
1882	=head3 Examples	1960	=head3 Examples
1883		1961
1884	There are a number of principal ways to embed other event loops or modules	1962	There are a number of principal ways to embed other event loops or modules
1885	into libev. Here are some ideas on how to include libadns into libev	1963	into libev. Here are some ideas on how to include libadns into libev
1886	(there is a Perl module named C<EV::ADNS> that does this, which you could	1964	(there is a Perl module named C<EV::ADNS> that does this, which you could
1887	use for an actually working example. Another Perl module named C<EV::Glib>	1965	use as a working example. Another Perl module named C<EV::Glib> embeds a
1888	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV	1966	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1889	into the Glib event loop).	1967	Glib event loop).
1890		1968
1891	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	1969	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1892	and in a check watcher, destroy them and call into libadns. What follows	1970	and in a check watcher, destroy them and call into libadns. What follows
1893	is pseudo-code only of course. This requires you to either use a low	1971	is pseudo-code only of course. This requires you to either use a low
1894	priority for the check watcher or use C<ev_clear_pending> explicitly, as	1972	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1895	the callbacks for the IO/timeout watchers might not have been called yet.	1973	the callbacks for the IO/timeout watchers might not have been called yet.
1896		1974
1897	static ev_io iow [nfd];	1975	static ev_io iow [nfd];
1898	static ev_timer tw;	1976	static ev_timer tw;
1899		1977
1900	static void	1978	static void
1901	io_cb (ev_loop *loop, ev_io *w, int revents)	1979	io_cb (ev_loop *loop, ev_io *w, int revents)
1902	{	1980	{
1903	}	1981	}
1904		1982
1905	// create io watchers for each fd and a timer before blocking	1983	// create io watchers for each fd and a timer before blocking
1906	static void	1984	static void
1907	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1985	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1908	{	1986	{
1909	int timeout = 3600000;	1987	int timeout = 3600000;
1910	struct pollfd fds [nfd];	1988	struct pollfd fds [nfd];
1911	// actual code will need to loop here and realloc etc.	1989	// actual code will need to loop here and realloc etc.
1912	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1990	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1913		1991
1914	/* the callback is illegal, but won't be called as we stop during check */	1992	/* the callback is illegal, but won't be called as we stop during check */
1915	ev_timer_init (&tw, 0, timeout * 1e-3);	1993	ev_timer_init (&tw, 0, timeout * 1e-3);
1916	ev_timer_start (loop, &tw);	1994	ev_timer_start (loop, &tw);
1917		1995
1918	// create one ev_io per pollfd	1996	// create one ev_io per pollfd
1919	for (int i = 0; i < nfd; ++i)	1997	for (int i = 0; i < nfd; ++i)
1920	{	1998	{
1921	ev_io_init (iow + i, io_cb, fds [i].fd,	1999	ev_io_init (iow + i, io_cb, fds [i].fd,
1922	((fds [i].events & POLLIN ? EV_READ : 0)	2000	((fds [i].events & POLLIN ? EV_READ : 0)
1923	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	2001	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1924		2002
1925	fds [i].revents = 0;	2003	fds [i].revents = 0;
1926	ev_io_start (loop, iow + i);	2004	ev_io_start (loop, iow + i);
1927	}	2005	}
1928	}	2006	}
1929		2007
1930	// stop all watchers after blocking	2008	// stop all watchers after blocking
1931	static void	2009	static void
1932	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	2010	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1933	{	2011	{
1934	ev_timer_stop (loop, &tw);	2012	ev_timer_stop (loop, &tw);
1935		2013
1936	for (int i = 0; i < nfd; ++i)	2014	for (int i = 0; i < nfd; ++i)
1937	{	2015	{
1938	// set the relevant poll flags	2016	// set the relevant poll flags
1939	// could also call adns_processreadable etc. here	2017	// could also call adns_processreadable etc. here
1940	struct pollfd *fd = fds + i;	2018	struct pollfd *fd = fds + i;
1941	int revents = ev_clear_pending (iow + i);	2019	int revents = ev_clear_pending (iow + i);
1942	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	2020	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1943	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	2021	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1944		2022
1945	// now stop the watcher	2023	// now stop the watcher
1946	ev_io_stop (loop, iow + i);	2024	ev_io_stop (loop, iow + i);
1947	}	2025	}
1948		2026
1949	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2027	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1950	}	2028	}
1951		2029
1952	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2030	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
1953	in the prepare watcher and would dispose of the check watcher.	2031	in the prepare watcher and would dispose of the check watcher.
1954		2032
1955	Method 3: If the module to be embedded supports explicit event	2033	Method 3: If the module to be embedded supports explicit event
1956	notification (adns does), you can also make use of the actual watcher	2034	notification (libadns does), you can also make use of the actual watcher
1957	callbacks, and only destroy/create the watchers in the prepare watcher.	2035	callbacks, and only destroy/create the watchers in the prepare watcher.
1958		2036
1959	static void	2037	static void
1960	timer_cb (EV_P_ ev_timer *w, int revents)	2038	timer_cb (EV_P_ ev_timer *w, int revents)
1961	{	2039	{
1962	adns_state ads = (adns_state)w->data;	2040	adns_state ads = (adns_state)w->data;
1963	update_now (EV_A);	2041	update_now (EV_A);
1964		2042
1965	adns_processtimeouts (ads, &tv_now);	2043	adns_processtimeouts (ads, &tv_now);
1966	}	2044	}
1967		2045
1968	static void	2046	static void
1969	io_cb (EV_P_ ev_io *w, int revents)	2047	io_cb (EV_P_ ev_io *w, int revents)
1970	{	2048	{
1971	adns_state ads = (adns_state)w->data;	2049	adns_state ads = (adns_state)w->data;
1972	update_now (EV_A);	2050	update_now (EV_A);
1973		2051
1974	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2052	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1975	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2053	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1976	}	2054	}
1977		2055
1978	// do not ever call adns_afterpoll	2056	// do not ever call adns_afterpoll
1979		2057
1980	Method 4: Do not use a prepare or check watcher because the module you	2058	Method 4: Do not use a prepare or check watcher because the module you
1981	want to embed is too inflexible to support it. Instead, youc na override	2059	want to embed is too inflexible to support it. Instead, you can override
1982	their poll function. The drawback with this solution is that the main	2060	their poll function. The drawback with this solution is that the main
1983	loop is now no longer controllable by EV. The C<Glib::EV> module does	2061	loop is now no longer controllable by EV. The C<Glib::EV> module does
1984	this.	2062	this.
1985		2063
1986	static gint	2064	static gint
1987	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2065	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1988	{	2066	{
1989	int got_events = 0;	2067	int got_events = 0;
1990		2068
1991	for (n = 0; n < nfds; ++n)	2069	for (n = 0; n < nfds; ++n)
1992	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2070	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1993		2071
1994	if (timeout >= 0)	2072	if (timeout >= 0)
1995	// create/start timer	2073	// create/start timer
1996		2074
1997	// poll	2075	// poll
1998	ev_loop (EV_A_ 0);	2076	ev_loop (EV_A_ 0);
1999		2077
2000	// stop timer again	2078	// stop timer again
2001	if (timeout >= 0)	2079	if (timeout >= 0)
2002	ev_timer_stop (EV_A_ &to);	2080	ev_timer_stop (EV_A_ &to);
2003		2081
2004	// stop io watchers again - their callbacks should have set	2082	// stop io watchers again - their callbacks should have set
2005	for (n = 0; n < nfds; ++n)	2083	for (n = 0; n < nfds; ++n)
2006	ev_io_stop (EV_A_ iow [n]);	2084	ev_io_stop (EV_A_ iow [n]);
2007		2085
2008	return got_events;	2086	return got_events;
2009	}	2087	}
2010		2088
2011		2089
2012	=head2 C<ev_embed> - when one backend isn't enough...	2090	=head2 C<ev_embed> - when one backend isn't enough...
2013		2091
2014	This is a rather advanced watcher type that lets you embed one event loop	2092	This is a rather advanced watcher type that lets you embed one event loop
…		…
2070		2148
2071	Configures the watcher to embed the given loop, which must be	2149	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	2150	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	2151	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,	2152	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).	2153	if you do not want that, you need to temporarily stop the embed watcher).
2076		2154
2077	=item ev_embed_sweep (loop, ev_embed *)	2155	=item ev_embed_sweep (loop, ev_embed *)
2078		2156
2079	Make a single, non-blocking sweep over the embedded loop. This works	2157	Make a single, non-blocking sweep over the embedded loop. This works
2080	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2158	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2081	apropriate way for embedded loops.	2159	appropriate way for embedded loops.
2082		2160
2083	=item struct ev_loop *other [read-only]	2161	=item struct ev_loop *other [read-only]
2084		2162
2085	The embedded event loop.	2163	The embedded event loop.
2086		2164
…		…
2088		2166
2089	=head3 Examples	2167	=head3 Examples
2090		2168
2091	Example: Try to get an embeddable event loop and embed it into the default	2169	Example: Try to get an embeddable event loop and embed it into the default
2092	event loop. If that is not possible, use the default loop. The default	2170	event loop. If that is not possible, use the default loop. The default
2093	loop is stored in C<loop_hi>, while the mebeddable loop is stored in	2171	loop is stored in C<loop_hi>, while the embeddable loop is stored in
2094	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be	2172	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2095	used).	2173	used).
2096		2174
2097	struct ev_loop *loop_hi = ev_default_init (0);	2175	struct ev_loop *loop_hi = ev_default_init (0);
2098	struct ev_loop *loop_lo = 0;	2176	struct ev_loop *loop_lo = 0;
2099	struct ev_embed embed;	2177	struct ev_embed embed;
2100		2178
2101	// see if there is a chance of getting one that works	2179	// see if there is a chance of getting one that works
2102	// (remember that a flags value of 0 means autodetection)	2180	// (remember that a flags value of 0 means autodetection)
2103	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2181	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2104	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2182	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2105	: 0;	2183	: 0;
2106		2184
2107	// if we got one, then embed it, otherwise default to loop_hi	2185	// if we got one, then embed it, otherwise default to loop_hi
2108	if (loop_lo)	2186	if (loop_lo)
2109	{	2187	{
2110	ev_embed_init (&embed, 0, loop_lo);	2188	ev_embed_init (&embed, 0, loop_lo);
2111	ev_embed_start (loop_hi, &embed);	2189	ev_embed_start (loop_hi, &embed);
2112	}	2190	}
2113	else	2191	else
2114	loop_lo = loop_hi;	2192	loop_lo = loop_hi;
2115		2193
2116	Example: Check if kqueue is available but not recommended and create	2194	Example: Check if kqueue is available but not recommended and create
2117	a kqueue backend for use with sockets (which usually work with any	2195	a kqueue backend for use with sockets (which usually work with any
2118	kqueue implementation). Store the kqueue/socket-only event loop in	2196	kqueue implementation). Store the kqueue/socket-only event loop in
2119	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2197	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2120		2198
2121	struct ev_loop *loop = ev_default_init (0);	2199	struct ev_loop *loop = ev_default_init (0);
2122	struct ev_loop *loop_socket = 0;	2200	struct ev_loop *loop_socket = 0;
2123	struct ev_embed embed;	2201	struct ev_embed embed;
2124		2202
2125	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2203	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2126	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2204	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2127	{	2205	{
2128	ev_embed_init (&embed, 0, loop_socket);	2206	ev_embed_init (&embed, 0, loop_socket);
2129	ev_embed_start (loop, &embed);	2207	ev_embed_start (loop, &embed);
2130	}	2208	}
2131		2209
2132	if (!loop_socket)	2210	if (!loop_socket)
2133	loop_socket = loop;	2211	loop_socket = loop;
2134		2212
2135	// now use loop_socket for all sockets, and loop for everything else	2213	// now use loop_socket for all sockets, and loop for everything else
2136		2214
2137		2215
2138	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2216	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2139		2217
2140	Fork watchers are called when a C<fork ()> was detected (usually because	2218	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2193		2271
2194	=item queueing from a signal handler context	2272	=item queueing from a signal handler context
2195		2273
2196	To implement race-free queueing, you simply add to the queue in the signal	2274	To implement race-free queueing, you simply add to the queue in the signal
2197	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2275	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2198	some fictitiuous SIGUSR1 handler:	2276	some fictitious SIGUSR1 handler:
2199		2277
2200	static ev_async mysig;	2278	static ev_async mysig;
2201		2279
2202	static void	2280	static void
2203	sigusr1_handler (void)	2281	sigusr1_handler (void)
…		…
2277	=item ev_async_send (loop, ev_async *)	2355	=item ev_async_send (loop, ev_async *)
2278		2356
2279	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2357	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2280	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2358	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2281	C<ev_feed_event>, this call is safe to do in other threads, signal or	2359	C<ev_feed_event>, this call is safe to do in other threads, signal or
2282	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding	2360	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2283	section below on what exactly this means).	2361	section below on what exactly this means).
2284		2362
2285	This call incurs the overhead of a syscall only once per loop iteration,	2363	This call incurs the overhead of a system call only once per loop iteration,
2286	so while the overhead might be noticable, it doesn't apply to repeated	2364	so while the overhead might be noticeable, it doesn't apply to repeated
2287	calls to C<ev_async_send>.	2365	calls to C<ev_async_send>.
2288		2366
2289	=item bool = ev_async_pending (ev_async *)	2367	=item bool = ev_async_pending (ev_async *)
2290		2368
2291	Returns a non-zero value when C<ev_async_send> has been called on the	2369	Returns a non-zero value when C<ev_async_send> has been called on the
…		…
2293	event loop.	2371	event loop.
2294		2372
2295	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When	2373	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
2296	the loop iterates next and checks for the watcher to have become active,	2374	the loop iterates next and checks for the watcher to have become active,
2297	it will reset the flag again. C<ev_async_pending> can be used to very	2375	it will reset the flag again. C<ev_async_pending> can be used to very
2298	quickly check wether invoking the loop might be a good idea.	2376	quickly check whether invoking the loop might be a good idea.
2299		2377
2300	Not that this does I<not> check wether the watcher itself is pending, only	2378	Not that this does I<not> check whether the watcher itself is pending, only
2301	wether it has been requested to make this watcher pending.	2379	whether it has been requested to make this watcher pending.
2302		2380
2303	=back	2381	=back
2304		2382
2305		2383
2306	=head1 OTHER FUNCTIONS	2384	=head1 OTHER FUNCTIONS
…		…
2317	or timeout without having to allocate/configure/start/stop/free one or	2395	or timeout without having to allocate/configure/start/stop/free one or
2318	more watchers yourself.	2396	more watchers yourself.
2319		2397
2320	If C<fd> is less than 0, then no I/O watcher will be started and events	2398	If C<fd> is less than 0, then no I/O watcher will be started and events
2321	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2399	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2322	C<events> set will be craeted and started.	2400	C<events> set will be created and started.
2323		2401
2324	If C<timeout> is less than 0, then no timeout watcher will be	2402	If C<timeout> is less than 0, then no timeout watcher will be
2325	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2403	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2326	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2404	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2327	dubious value.	2405	dubious value.
…		…
2329	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2407	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2330	passed an C<revents> set like normal event callbacks (a combination of	2408	passed an C<revents> set like normal event callbacks (a combination of
2331	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2409	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2332	value passed to C<ev_once>:	2410	value passed to C<ev_once>:
2333		2411
2334	static void stdin_ready (int revents, void *arg)	2412	static void stdin_ready (int revents, void *arg)
2335	{	2413	{
2336	if (revents & EV_TIMEOUT)	2414	if (revents & EV_TIMEOUT)
2337	/* doh, nothing entered */;	2415	/* doh, nothing entered */;
2338	else if (revents & EV_READ)	2416	else if (revents & EV_READ)
2339	/* stdin might have data for us, joy! */;	2417	/* stdin might have data for us, joy! */;
2340	}	2418	}
2341		2419
2342	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2420	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2343		2421
2344	=item ev_feed_event (ev_loop *, watcher *, int revents)	2422	=item ev_feed_event (ev_loop *, watcher *, int revents)
2345		2423
2346	Feeds the given event set into the event loop, as if the specified event	2424	Feeds the given event set into the event loop, as if the specified event
2347	had happened for the specified watcher (which must be a pointer to an	2425	had happened for the specified watcher (which must be a pointer to an
…		…
2352	Feed an event on the given fd, as if a file descriptor backend detected	2430	Feed an event on the given fd, as if a file descriptor backend detected
2353	the given events it.	2431	the given events it.
2354		2432
2355	=item ev_feed_signal_event (ev_loop *loop, int signum)	2433	=item ev_feed_signal_event (ev_loop *loop, int signum)
2356		2434
2357	Feed an event as if the given signal occured (C<loop> must be the default	2435	Feed an event as if the given signal occurred (C<loop> must be the default
2358	loop!).	2436	loop!).
2359		2437
2360	=back	2438	=back
2361		2439
2362		2440
…		…
2391	=back	2469	=back
2392		2470
2393	=head1 C++ SUPPORT	2471	=head1 C++ SUPPORT
2394		2472
2395	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2473	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2396	you to use some convinience methods to start/stop watchers and also change	2474	you to use some convenience methods to start/stop watchers and also change
2397	the callback model to a model using method callbacks on objects.	2475	the callback model to a model using method callbacks on objects.
2398		2476
2399	To use it,	2477	To use it,
2400		2478
2401	#include <ev++.h>	2479	#include <ev++.h>
2402		2480
2403	This automatically includes F<ev.h> and puts all of its definitions (many	2481	This automatically includes F<ev.h> and puts all of its definitions (many
2404	of them macros) into the global namespace. All C++ specific things are	2482	of them macros) into the global namespace. All C++ specific things are
2405	put into the C<ev> namespace. It should support all the same embedding	2483	put into the C<ev> namespace. It should support all the same embedding
2406	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2484	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2473	your compiler is good :), then the method will be fully inlined into the	2551	your compiler is good :), then the method will be fully inlined into the
2474	thunking function, making it as fast as a direct C callback.	2552	thunking function, making it as fast as a direct C callback.
2475		2553
2476	Example: simple class declaration and watcher initialisation	2554	Example: simple class declaration and watcher initialisation
2477		2555
2478	struct myclass	2556	struct myclass
2479	{	2557	{
2480	void io_cb (ev::io &w, int revents) { }	2558	void io_cb (ev::io &w, int revents) { }
2481	}	2559	}
2482		2560
2483	myclass obj;	2561	myclass obj;
2484	ev::io iow;	2562	ev::io iow;
2485	iow.set <myclass, &myclass::io_cb> (&obj);	2563	iow.set <myclass, &myclass::io_cb> (&obj);
2486		2564
2487	=item w->set<function> (void *data = 0)	2565	=item w->set<function> (void *data = 0)
2488		2566
2489	Also sets a callback, but uses a static method or plain function as	2567	Also sets a callback, but uses a static method or plain function as
2490	callback. The optional C<data> argument will be stored in the watcher's	2568	callback. The optional C<data> argument will be stored in the watcher's
…		…
2494		2572
2495	See the method-C<set> above for more details.	2573	See the method-C<set> above for more details.
2496		2574
2497	Example:	2575	Example:
2498		2576
2499	static void io_cb (ev::io &w, int revents) { }	2577	static void io_cb (ev::io &w, int revents) { }
2500	iow.set <io_cb> ();	2578	iow.set <io_cb> ();
2501		2579
2502	=item w->set (struct ev_loop *)	2580	=item w->set (struct ev_loop *)
2503		2581
2504	Associates a different C<struct ev_loop> with this watcher. You can only	2582	Associates a different C<struct ev_loop> with this watcher. You can only
2505	do this when the watcher is inactive (and not pending either).	2583	do this when the watcher is inactive (and not pending either).
2506		2584
2507	=item w->set ([args])	2585	=item w->set ([arguments])
2508		2586
2509	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2587	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2510	called at least once. Unlike the C counterpart, an active watcher gets	2588	called at least once. Unlike the C counterpart, an active watcher gets
2511	automatically stopped and restarted when reconfiguring it with this	2589	automatically stopped and restarted when reconfiguring it with this
2512	method.	2590	method.
2513		2591
2514	=item w->start ()	2592	=item w->start ()
…		…
2538	=back	2616	=back
2539		2617
2540	Example: Define a class with an IO and idle watcher, start one of them in	2618	Example: Define a class with an IO and idle watcher, start one of them in
2541	the constructor.	2619	the constructor.
2542		2620
2543	class myclass	2621	class myclass
2544	{	2622	{
2545	ev::io io; void io_cb (ev::io &w, int revents);	2623	ev::io io; void io_cb (ev::io &w, int revents);
2546	ev:idle idle void idle_cb (ev::idle &w, int revents);	2624	ev:idle idle void idle_cb (ev::idle &w, int revents);
2547		2625
2548	myclass (int fd)	2626	myclass (int fd)
2549	{	2627	{
2550	io .set <myclass, &myclass::io_cb > (this);	2628	io .set <myclass, &myclass::io_cb > (this);
2551	idle.set <myclass, &myclass::idle_cb> (this);	2629	idle.set <myclass, &myclass::idle_cb> (this);
2552		2630
2553	io.start (fd, ev::READ);	2631	io.start (fd, ev::READ);
2554	}	2632	}
2555	};	2633	};
2556		2634
2557		2635
2558	=head1 OTHER LANGUAGE BINDINGS	2636	=head1 OTHER LANGUAGE BINDINGS
2559		2637
2560	Libev does not offer other language bindings itself, but bindings for a	2638	Libev does not offer other language bindings itself, but bindings for a
2561	numbe rof languages exist in the form of third-party packages. If you know	2639	number of languages exist in the form of third-party packages. If you know
2562	any interesting language binding in addition to the ones listed here, drop	2640	any interesting language binding in addition to the ones listed here, drop
2563	me a note.	2641	me a note.
2564		2642
2565	=over 4	2643	=over 4
2566		2644
…		…
2570	libev. EV is developed together with libev. Apart from the EV core module,	2648	libev. EV is developed together with libev. Apart from the EV core module,
2571	there are additional modules that implement libev-compatible interfaces	2649	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	2650	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>).	2651	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2574		2652
2575	It can be found and installed via CPAN, its homepage is found at	2653	It can be found and installed via CPAN, its homepage is at
2576	L<http://software.schmorp.de/pkg/EV>.	2654	L<http://software.schmorp.de/pkg/EV>.
2577		2655
		2656	=item Python
		2657
		2658	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2659	seems to be quite complete and well-documented. Note, however, that the
		2660	patch they require for libev is outright dangerous as it breaks the ABI
		2661	for everybody else, and therefore, should never be applied in an installed
		2662	libev (if python requires an incompatible ABI then it needs to embed
		2663	libev).
		2664
2578	=item Ruby	2665	=item Ruby
2579		2666
2580	Tony Arcieri has written a ruby extension that offers access to a subset	2667	Tony Arcieri has written a ruby extension that offers access to a subset
2581	of the libev API and adds filehandle abstractions, asynchronous DNS and	2668	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	2669	more on top of it. It can be found via gem servers. Its homepage is at
2583	L<http://rev.rubyforge.org/>.	2670	L<http://rev.rubyforge.org/>.
2584		2671
2585	=item D	2672	=item D
2586		2673
2587	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	2674	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
2588	be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.	2675	be found at L<http://proj.llucax.com.ar/wiki/evd>.
2589		2676
2590	=back	2677	=back
2591		2678
2592		2679
2593	=head1 MACRO MAGIC	2680	=head1 MACRO MAGIC
2594		2681
2595	Libev can be compiled with a variety of options, the most fundamantal	2682	Libev can be compiled with a variety of options, the most fundamental
2596	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2683	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2597	functions and callbacks have an initial C<struct ev_loop *> argument.	2684	functions and callbacks have an initial C<struct ev_loop *> argument.
2598		2685
2599	To make it easier to write programs that cope with either variant, the	2686	To make it easier to write programs that cope with either variant, the
2600	following macros are defined:	2687	following macros are defined:
…		…
2605		2692
2606	This provides the loop I<argument> for functions, if one is required ("ev	2693	This provides the loop I<argument> for functions, if one is required ("ev
2607	loop argument"). The C<EV_A> form is used when this is the sole argument,	2694	loop argument"). The C<EV_A> form is used when this is the sole argument,
2608	C<EV_A_> is used when other arguments are following. Example:	2695	C<EV_A_> is used when other arguments are following. Example:
2609		2696
2610	ev_unref (EV_A);	2697	ev_unref (EV_A);
2611	ev_timer_add (EV_A_ watcher);	2698	ev_timer_add (EV_A_ watcher);
2612	ev_loop (EV_A_ 0);	2699	ev_loop (EV_A_ 0);
2613		2700
2614	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2701	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2615	which is often provided by the following macro.	2702	which is often provided by the following macro.
2616		2703
2617	=item C<EV_P>, C<EV_P_>	2704	=item C<EV_P>, C<EV_P_>
2618		2705
2619	This provides the loop I<parameter> for functions, if one is required ("ev	2706	This provides the loop I<parameter> for functions, if one is required ("ev
2620	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2707	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2621	C<EV_P_> is used when other parameters are following. Example:	2708	C<EV_P_> is used when other parameters are following. Example:
2622		2709
2623	// this is how ev_unref is being declared	2710	// this is how ev_unref is being declared
2624	static void ev_unref (EV_P);	2711	static void ev_unref (EV_P);
2625		2712
2626	// this is how you can declare your typical callback	2713	// this is how you can declare your typical callback
2627	static void cb (EV_P_ ev_timer *w, int revents)	2714	static void cb (EV_P_ ev_timer *w, int revents)
2628		2715
2629	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2716	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2630	suitable for use with C<EV_A>.	2717	suitable for use with C<EV_A>.
2631		2718
2632	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2719	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
…		…
2648		2735
2649	Example: Declare and initialise a check watcher, utilising the above	2736	Example: Declare and initialise a check watcher, utilising the above
2650	macros so it will work regardless of whether multiple loops are supported	2737	macros so it will work regardless of whether multiple loops are supported
2651	or not.	2738	or not.
2652		2739
2653	static void	2740	static void
2654	check_cb (EV_P_ ev_timer *w, int revents)	2741	check_cb (EV_P_ ev_timer *w, int revents)
2655	{	2742	{
2656	ev_check_stop (EV_A_ w);	2743	ev_check_stop (EV_A_ w);
2657	}	2744	}
2658		2745
2659	ev_check check;	2746	ev_check check;
2660	ev_check_init (&check, check_cb);	2747	ev_check_init (&check, check_cb);
2661	ev_check_start (EV_DEFAULT_ &check);	2748	ev_check_start (EV_DEFAULT_ &check);
2662	ev_loop (EV_DEFAULT_ 0);	2749	ev_loop (EV_DEFAULT_ 0);
2663		2750
2664	=head1 EMBEDDING	2751	=head1 EMBEDDING
2665		2752
2666	Libev can (and often is) directly embedded into host	2753	Libev can (and often is) directly embedded into host
2667	applications. Examples of applications that embed it include the Deliantra	2754	applications. Examples of applications that embed it include the Deliantra
…		…
2674	libev somewhere in your source tree).	2761	libev somewhere in your source tree).
2675		2762
2676	=head2 FILESETS	2763	=head2 FILESETS
2677		2764
2678	Depending on what features you need you need to include one or more sets of files	2765	Depending on what features you need you need to include one or more sets of files
2679	in your app.	2766	in your application.
2680		2767
2681	=head3 CORE EVENT LOOP	2768	=head3 CORE EVENT LOOP
2682		2769
2683	To include only the libev core (all the C<ev_*> functions), with manual	2770	To include only the libev core (all the C<ev_*> functions), with manual
2684	configuration (no autoconf):	2771	configuration (no autoconf):
2685		2772
2686	#define EV_STANDALONE 1	2773	#define EV_STANDALONE 1
2687	#include "ev.c"	2774	#include "ev.c"
2688		2775
2689	This will automatically include F<ev.h>, too, and should be done in a	2776	This will automatically include F<ev.h>, too, and should be done in a
2690	single C source file only to provide the function implementations. To use	2777	single C source file only to provide the function implementations. To use
2691	it, do the same for F<ev.h> in all files wishing to use this API (best	2778	it, do the same for F<ev.h> in all files wishing to use this API (best
2692	done by writing a wrapper around F<ev.h> that you can include instead and	2779	done by writing a wrapper around F<ev.h> that you can include instead and
2693	where you can put other configuration options):	2780	where you can put other configuration options):
2694		2781
2695	#define EV_STANDALONE 1	2782	#define EV_STANDALONE 1
2696	#include "ev.h"	2783	#include "ev.h"
2697		2784
2698	Both header files and implementation files can be compiled with a C++	2785	Both header files and implementation files can be compiled with a C++
2699	compiler (at least, thats a stated goal, and breakage will be treated	2786	compiler (at least, thats a stated goal, and breakage will be treated
2700	as a bug).	2787	as a bug).
2701		2788
2702	You need the following files in your source tree, or in a directory	2789	You need the following files in your source tree, or in a directory
2703	in your include path (e.g. in libev/ when using -Ilibev):	2790	in your include path (e.g. in libev/ when using -Ilibev):
2704		2791
2705	ev.h	2792	ev.h
2706	ev.c	2793	ev.c
2707	ev_vars.h	2794	ev_vars.h
2708	ev_wrap.h	2795	ev_wrap.h
2709		2796
2710	ev_win32.c required on win32 platforms only	2797	ev_win32.c required on win32 platforms only
2711		2798
2712	ev_select.c only when select backend is enabled (which is enabled by default)	2799	ev_select.c only when select backend is enabled (which is enabled by default)
2713	ev_poll.c only when poll backend is enabled (disabled by default)	2800	ev_poll.c only when poll backend is enabled (disabled by default)
2714	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2801	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2715	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2802	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2716	ev_port.c only when the solaris port backend is enabled (disabled by default)	2803	ev_port.c only when the solaris port backend is enabled (disabled by default)
2717		2804
2718	F<ev.c> includes the backend files directly when enabled, so you only need	2805	F<ev.c> includes the backend files directly when enabled, so you only need
2719	to compile this single file.	2806	to compile this single file.
2720		2807
2721	=head3 LIBEVENT COMPATIBILITY API	2808	=head3 LIBEVENT COMPATIBILITY API
2722		2809
2723	To include the libevent compatibility API, also include:	2810	To include the libevent compatibility API, also include:
2724		2811
2725	#include "event.c"	2812	#include "event.c"
2726		2813
2727	in the file including F<ev.c>, and:	2814	in the file including F<ev.c>, and:
2728		2815
2729	#include "event.h"	2816	#include "event.h"
2730		2817
2731	in the files that want to use the libevent API. This also includes F<ev.h>.	2818	in the files that want to use the libevent API. This also includes F<ev.h>.
2732		2819
2733	You need the following additional files for this:	2820	You need the following additional files for this:
2734		2821
2735	event.h	2822	event.h
2736	event.c	2823	event.c
2737		2824
2738	=head3 AUTOCONF SUPPORT	2825	=head3 AUTOCONF SUPPORT
2739		2826
2740	Instead of using C<EV_STANDALONE=1> and providing your config in	2827	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2741	whatever way you want, you can also C<m4_include([libev.m4])> in your	2828	whatever way you want, you can also C<m4_include([libev.m4])> in your
2742	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2829	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2743	include F<config.h> and configure itself accordingly.	2830	include F<config.h> and configure itself accordingly.
2744		2831
2745	For this of course you need the m4 file:	2832	For this of course you need the m4 file:
2746		2833
2747	libev.m4	2834	libev.m4
2748		2835
2749	=head2 PREPROCESSOR SYMBOLS/MACROS	2836	=head2 PREPROCESSOR SYMBOLS/MACROS
2750		2837
2751	Libev can be configured via a variety of preprocessor symbols you have to	2838	Libev can be configured via a variety of preprocessor symbols you have to
2752	define before including any of its files. The default in the absense of	2839	define before including any of its files. The default in the absence of
2753	autoconf is noted for every option.	2840	autoconf is noted for every option.
2754		2841
2755	=over 4	2842	=over 4
2756		2843
2757	=item EV_STANDALONE	2844	=item EV_STANDALONE
…		…
2763	F<event.h> that are not directly supported by the libev core alone.	2850	F<event.h> that are not directly supported by the libev core alone.
2764		2851
2765	=item EV_USE_MONOTONIC	2852	=item EV_USE_MONOTONIC
2766		2853
2767	If defined to be C<1>, libev will try to detect the availability of the	2854	If defined to be C<1>, libev will try to detect the availability of the
2768	monotonic clock option at both compiletime and runtime. Otherwise no use	2855	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	2856	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	2857	usually have to link against librt or something similar. Enabling it when
2771	the functionality isn't available is safe, though, although you have	2858	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>	2859	to make sure you link against any libraries where the C<clock_gettime>
2773	function is hiding in (often F<-lrt>).	2860	function is hiding in (often F<-lrt>).
2774		2861
2775	=item EV_USE_REALTIME	2862	=item EV_USE_REALTIME
2776		2863
2777	If defined to be C<1>, libev will try to detect the availability of the	2864	If defined to be C<1>, libev will try to detect the availability of the
2778	realtime clock option at compiletime (and assume its availability at	2865	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	2866	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	2867	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2781	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2868	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2782	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2869	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2783		2870
2784	=item EV_USE_NANOSLEEP	2871	=item EV_USE_NANOSLEEP
…		…
2795	2.7 or newer, otherwise disabled.	2882	2.7 or newer, otherwise disabled.
2796		2883
2797	=item EV_USE_SELECT	2884	=item EV_USE_SELECT
2798		2885
2799	If undefined or defined to be C<1>, libev will compile in support for the	2886	If undefined or defined to be C<1>, libev will compile in support for the
2800	C<select>(2) backend. No attempt at autodetection will be done: if no	2887	C<select>(2) backend. No attempt at auto-detection will be done: if no
2801	other method takes over, select will be it. Otherwise the select backend	2888	other method takes over, select will be it. Otherwise the select backend
2802	will not be compiled in.	2889	will not be compiled in.
2803		2890
2804	=item EV_SELECT_USE_FD_SET	2891	=item EV_SELECT_USE_FD_SET
2805		2892
2806	If defined to C<1>, then the select backend will use the system C<fd_set>	2893	If defined to C<1>, then the select backend will use the system C<fd_set>
2807	structure. This is useful if libev doesn't compile due to a missing	2894	structure. This is useful if libev doesn't compile due to a missing
2808	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	2895	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
2809	exotic systems. This usually limits the range of file descriptors to some	2896	exotic systems. This usually limits the range of file descriptors to some
2810	low limit such as 1024 or might have other limitations (winsocket only	2897	low limit such as 1024 or might have other limitations (winsocket only
2811	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	2898	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2812	influence the size of the C<fd_set> used.	2899	influence the size of the C<fd_set> used.
2813		2900
…		…
2862	otherwise another method will be used as fallback. This is the preferred	2949	otherwise another method will be used as fallback. This is the preferred
2863	backend for Solaris 10 systems.	2950	backend for Solaris 10 systems.
2864		2951
2865	=item EV_USE_DEVPOLL	2952	=item EV_USE_DEVPOLL
2866		2953
2867	reserved for future expansion, works like the USE symbols above.	2954	Reserved for future expansion, works like the USE symbols above.
2868		2955
2869	=item EV_USE_INOTIFY	2956	=item EV_USE_INOTIFY
2870		2957
2871	If defined to be C<1>, libev will compile in support for the Linux inotify	2958	If defined to be C<1>, libev will compile in support for the Linux inotify
2872	interface to speed up C<ev_stat> watchers. Its actual availability will	2959	interface to speed up C<ev_stat> watchers. Its actual availability will
…		…
2879	access is atomic with respect to other threads or signal contexts. No such	2966	access is atomic with respect to other threads or signal contexts. No such
2880	type is easily found in the C language, so you can provide your own type	2967	type is easily found in the C language, so you can provide your own type
2881	that you know is safe for your purposes. It is used both for signal handler "locking"	2968	that you know is safe for your purposes. It is used both for signal handler "locking"
2882	as well as for signal and thread safety in C<ev_async> watchers.	2969	as well as for signal and thread safety in C<ev_async> watchers.
2883		2970
2884	In the absense of this define, libev will use C<sig_atomic_t volatile>	2971	In the absence of this define, libev will use C<sig_atomic_t volatile>
2885	(from F<signal.h>), which is usually good enough on most platforms.	2972	(from F<signal.h>), which is usually good enough on most platforms.
2886		2973
2887	=item EV_H	2974	=item EV_H
2888		2975
2889	The name of the F<ev.h> header file used to include it. The default if	2976	The name of the F<ev.h> header file used to include it. The default if
…		…
2928	When doing priority-based operations, libev usually has to linearly search	3015	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	3016	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	3017	and time, so using the defaults of five priorities (-2 .. +2) is usually
2931	fine.	3018	fine.
2932		3019
2933	If your embedding app does not need any priorities, defining these both to	3020	If your embedding application does not need any priorities, defining these both to
2934	C<0> will save some memory and cpu.	3021	C<0> will save some memory and CPU.
2935		3022
2936	=item EV_PERIODIC_ENABLE	3023	=item EV_PERIODIC_ENABLE
2937		3024
2938	If undefined or defined to be C<1>, then periodic timers are supported. If	3025	If undefined or defined to be C<1>, then periodic timers are supported. If
2939	defined to be C<0>, then they are not. Disabling them saves a few kB of	3026	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
2966	defined to be C<0>, then they are not.	3053	defined to be C<0>, then they are not.
2967		3054
2968	=item EV_MINIMAL	3055	=item EV_MINIMAL
2969		3056
2970	If you need to shave off some kilobytes of code at the expense of some	3057	If you need to shave off some kilobytes of code at the expense of some
2971	speed, define this symbol to C<1>. Currently only used for gcc to override	3058	speed, define this symbol to C<1>. Currently this is used to override some
2972	some inlining decisions, saves roughly 30% codesize of amd64.	3059	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3060	much smaller 2-heap for timer management over the default 4-heap.
2973		3061
2974	=item EV_PID_HASHSIZE	3062	=item EV_PID_HASHSIZE
2975		3063
2976	C<ev_child> watchers use a small hash table to distribute workload by	3064	C<ev_child> watchers use a small hash table to distribute workload by
2977	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3065	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
…		…
2984	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	3072	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2985	usually more than enough. If you need to manage thousands of C<ev_stat>	3073	usually more than enough. If you need to manage thousands of C<ev_stat>
2986	watchers you might want to increase this value (I<must> be a power of	3074	watchers you might want to increase this value (I<must> be a power of
2987	two).	3075	two).
2988		3076
		3077	=item EV_USE_4HEAP
		3078
		3079	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3080	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3081	to C<1>. The 4-heap uses more complicated (longer) code but has
		3082	noticeably faster performance with many (thousands) of watchers.
		3083
		3084	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3085	(disabled).
		3086
		3087	=item EV_HEAP_CACHE_AT
		3088
		3089	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3090	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3091	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3092	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3093	but avoids random read accesses on heap changes. This improves performance
		3094	noticeably with with many (hundreds) of watchers.
		3095
		3096	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3097	(disabled).
		3098
		3099	=item EV_VERIFY
		3100
		3101	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3102	be done: If set to C<0>, no internal verification code will be compiled
		3103	in. If set to C<1>, then verification code will be compiled in, but not
		3104	called. If set to C<2>, then the internal verification code will be
		3105	called once per loop, which can slow down libev. If set to C<3>, then the
		3106	verification code will be called very frequently, which will slow down
		3107	libev considerably.
		3108
		3109	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3110	C<0.>
		3111
2989	=item EV_COMMON	3112	=item EV_COMMON
2990		3113
2991	By default, all watchers have a C<void *data> member. By redefining	3114	By default, all watchers have a C<void *data> member. By redefining
2992	this macro to a something else you can include more and other types of	3115	this macro to a something else you can include more and other types of
2993	members. You have to define it each time you include one of the files,	3116	members. You have to define it each time you include one of the files,
2994	though, and it must be identical each time.	3117	though, and it must be identical each time.
2995		3118
2996	For example, the perl EV module uses something like this:	3119	For example, the perl EV module uses something like this:
2997		3120
2998	#define EV_COMMON \	3121	#define EV_COMMON \
2999	SV *self; /* contains this struct */ \	3122	SV *self; /* contains this struct */ \
3000	SV *cb_sv, *fh /* note no trailing ";" */	3123	SV *cb_sv, *fh /* note no trailing ";" */
3001		3124
3002	=item EV_CB_DECLARE (type)	3125	=item EV_CB_DECLARE (type)
3003		3126
3004	=item EV_CB_INVOKE (watcher, revents)	3127	=item EV_CB_INVOKE (watcher, revents)
3005		3128
…		…
3012	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3135	avoid the C<struct ev_loop *> as first argument in all cases, or to use
3013	method calls instead of plain function calls in C++.	3136	method calls instead of plain function calls in C++.
3014		3137
3015	=head2 EXPORTED API SYMBOLS	3138	=head2 EXPORTED API SYMBOLS
3016		3139
3017	If you need to re-export the API (e.g. via a dll) and you need a list of	3140	If you need to re-export the API (e.g. via a DLL) and you need a list of
3018	exported symbols, you can use the provided F<Symbol.*> files which list	3141	exported symbols, you can use the provided F<Symbol.*> files which list
3019	all public symbols, one per line:	3142	all public symbols, one per line:
3020		3143
3021	Symbols.ev for libev proper	3144	Symbols.ev for libev proper
3022	Symbols.event for the libevent emulation	3145	Symbols.event for the libevent emulation
3023		3146
3024	This can also be used to rename all public symbols to avoid clashes with	3147	This can also be used to rename all public symbols to avoid clashes with
3025	multiple versions of libev linked together (which is obviously bad in	3148	multiple versions of libev linked together (which is obviously bad in
3026	itself, but sometimes it is inconvinient to avoid this).	3149	itself, but sometimes it is inconvenient to avoid this).
3027		3150
3028	A sed command like this will create wrapper C<#define>'s that you need to	3151	A sed command like this will create wrapper C<#define>'s that you need to
3029	include before including F<ev.h>:	3152	include before including F<ev.h>:
3030		3153
3031	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3154	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3048	file.	3171	file.
3049		3172
3050	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3173	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3051	that everybody includes and which overrides some configure choices:	3174	that everybody includes and which overrides some configure choices:
3052		3175
3053	#define EV_MINIMAL 1	3176	#define EV_MINIMAL 1
3054	#define EV_USE_POLL 0	3177	#define EV_USE_POLL 0
3055	#define EV_MULTIPLICITY 0	3178	#define EV_MULTIPLICITY 0
3056	#define EV_PERIODIC_ENABLE 0	3179	#define EV_PERIODIC_ENABLE 0
3057	#define EV_STAT_ENABLE 0	3180	#define EV_STAT_ENABLE 0
3058	#define EV_FORK_ENABLE 0	3181	#define EV_FORK_ENABLE 0
3059	#define EV_CONFIG_H <config.h>	3182	#define EV_CONFIG_H <config.h>
3060	#define EV_MINPRI 0	3183	#define EV_MINPRI 0
3061	#define EV_MAXPRI 0	3184	#define EV_MAXPRI 0
3062		3185
3063	#include "ev++.h"	3186	#include "ev++.h"
3064		3187
3065	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3188	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3066		3189
3067	#include "ev_cpp.h"	3190	#include "ev_cpp.h"
3068	#include "ev.c"	3191	#include "ev.c"
3069		3192
3070		3193
3071	=head1 THREADS AND COROUTINES	3194	=head1 THREADS AND COROUTINES
3072		3195
3073	=head2 THREADS	3196	=head2 THREADS
3074		3197
3075	Libev itself is completely threadsafe, but it uses no locking. This	3198	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	3199	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	3200	only one thread ever calls into one libev function with the same loop
3078	parameter.	3201	parameter.
3079		3202
3080	Or put differently: calls with different loop parameters can be done in	3203	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	3204	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	3205	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	3206	thread ever is inside a call at any point in time, e.g. by using a mutex
3084	per loop).	3207	per loop).
3085		3208
3086	If you want to know which design is best for your problem, then I cannot	3209	If you want to know which design (one loop, locking, or multiple loops
3087	help you but by giving some generic advice:	3210	without or something else still) is best for your problem, then I cannot
		3211	help you. I can give some generic advice however:
3088		3212
3089	=over 4	3213	=over 4
3090		3214
3091	=item * most applications have a main thread: use the default libev loop	3215	=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.	3216	in that thread, or create a separate thread running only the default loop.
3093		3217
3094	This helps integrating other libraries or software modules that use libev	3218	This helps integrating other libraries or software modules that use libev
3095	themselves and don't care/know about threading.	3219	themselves and don't care/know about threading.
3096		3220
3097	=item * one loop per thread is usually a good model.	3221	=item * one loop per thread is usually a good model.
3098		3222
3099	Doing this is almost never wrong, sometimes a better-performance model	3223	Doing this is almost never wrong, sometimes a better-performance model
3100	exists, but it is always a good start.	3224	exists, but it is always a good start.
3101		3225
3102	=item * other models exist, such as the leader/follower pattern, where one	3226	=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.	3227	loop is handed through multiple threads in a kind of round-robin fashion.
3104		3228
3105	Chosing a model is hard - look around, learn, know that usually you cna do	3229	Choosing a model is hard - look around, learn, know that usually you can do
3106	better than you currently do :-)	3230	better than you currently do :-)
3107		3231
3108	=item * often you need to talk to some other thread which blocks in the	3232	=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	3233	event loop - C<ev_async> watchers can be used to wake them up from other
3110	threads safely (or from signal contexts...).	3234	threads safely (or from signal contexts...).
3111		3235
3112	=back	3236	=back
3113		3237
3114	=head2 COROUTINES	3238	=head2 COROUTINES
3115		3239
3116	Libev is much more accomodating to coroutines ("cooperative threads"):	3240	Libev is much more accommodating to coroutines ("cooperative threads"):
3117	libev fully supports nesting calls to it's functions from different	3241	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	3242	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	3243	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	3244	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.	3245	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	3286	correct watcher to remove. The lists are usually short (you don't usually
3163	have many watchers waiting for the same fd or signal).	3287	have many watchers waiting for the same fd or signal).
3164		3288
3165	=item Finding the next timer in each loop iteration: O(1)	3289	=item Finding the next timer in each loop iteration: O(1)
3166		3290
3167	By virtue of using a binary heap, the next timer is always found at the	3291	By virtue of using a binary or 4-heap, the next timer is always found at a
3168	beginning of the storage array.	3292	fixed position in the storage array.
3169		3293
3170	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3294	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3171		3295
3172	A change means an I/O watcher gets started or stopped, which requires	3296	A change means an I/O watcher gets started or stopped, which requires
3173	libev to recalculate its status (and possibly tell the kernel, depending	3297	libev to recalculate its status (and possibly tell the kernel, depending
3174	on backend and wether C<ev_io_set> was used).	3298	on backend and whether C<ev_io_set> was used).
3175		3299
3176	=item Activating one watcher (putting it into the pending state): O(1)	3300	=item Activating one watcher (putting it into the pending state): O(1)
3177		3301
3178	=item Priority handling: O(number_of_priorities)	3302	=item Priority handling: O(number_of_priorities)
3179		3303
…		…
3186		3310
3187	=item Processing ev_async_send: O(number_of_async_watchers)	3311	=item Processing ev_async_send: O(number_of_async_watchers)
3188		3312
3189	=item Processing signals: O(max_signal_number)	3313	=item Processing signals: O(max_signal_number)
3190		3314
3191	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3315	Sending involves a system call I<iff> there were no other C<ev_async_send>
3192	calls in the current loop iteration. Checking for async and signal events	3316	calls in the current loop iteration. Checking for async and signal events
3193	involves iterating over all running async watchers or all signal numbers.	3317	involves iterating over all running async watchers or all signal numbers.
3194		3318
3195	=back	3319	=back
3196		3320
3197		3321
3198	=head1 Win32 platform limitations and workarounds	3322	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3199		3323
3200	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3324	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3201	requires, and its I/O model is fundamentally incompatible with the POSIX	3325	requires, and its I/O model is fundamentally incompatible with the POSIX
3202	model. Libev still offers limited functionality on this platform in	3326	model. Libev still offers limited functionality on this platform in
3203	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3327	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3204	descriptors. This only applies when using Win32 natively, not when using	3328	descriptors. This only applies when using Win32 natively, not when using
3205	e.g. cygwin.	3329	e.g. cygwin.
3206		3330
		3331	Lifting these limitations would basically require the full
		3332	re-implementation of the I/O system. If you are into these kinds of
		3333	things, then note that glib does exactly that for you in a very portable
		3334	way (note also that glib is the slowest event library known to man).
		3335
3207	There is no supported compilation method available on windows except	3336	There is no supported compilation method available on windows except
3208	embedding it into other applications.	3337	embedding it into other applications.
3209		3338
		3339	Not a libev limitation but worth mentioning: windows apparently doesn't
		3340	accept large writes: instead of resulting in a partial write, windows will
		3341	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3342	so make sure you only write small amounts into your sockets (less than a
		3343	megabyte seems safe, but thsi apparently depends on the amount of memory
		3344	available).
		3345
3210	Due to the many, low, and arbitrary limits on the win32 platform and the	3346	Due to the many, low, and arbitrary limits on the win32 platform and
3211	abysmal performance of winsockets, using a large number of sockets is not	3347	the abysmal performance of winsockets, using a large number of sockets
3212	recommended (and not reasonable). If your program needs to use more than	3348	is not recommended (and not reasonable). If your program needs to use
3213	a hundred or so sockets, then likely it needs to use a totally different	3349	more than a hundred or so sockets, then likely it needs to use a totally
3214	implementation for windows, as libev offers the POSIX model, which cannot	3350	different implementation for windows, as libev offers the POSIX readiness
3215	be implemented efficiently on windows (microsoft monopoly games).	3351	notification model, which cannot be implemented efficiently on windows
		3352	(Microsoft monopoly games).
		3353
		3354	A typical way to use libev under windows is to embed it (see the embedding
		3355	section for details) and use the following F<evwrap.h> header file instead
		3356	of F<ev.h>:
		3357
		3358	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3359	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3360
		3361	#include "ev.h"
		3362
		3363	And compile the following F<evwrap.c> file into your project (make sure
		3364	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3365
		3366	#include "evwrap.h"
		3367	#include "ev.c"
3216		3368
3217	=over 4	3369	=over 4
3218		3370
3219	=item The winsocket select function	3371	=item The winsocket select function
3220		3372
3221	The winsocket C<select> function doesn't follow POSIX in that it requires	3373	The winsocket C<select> function doesn't follow POSIX in that it
3222	socket I<handles> and not socket I<file descriptors>. This makes select	3374	requires socket I<handles> and not socket I<file descriptors> (it is
3223	very inefficient, and also requires a mapping from file descriptors	3375	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>,	3376	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	3377	C runtime provides the function C<_open_osfhandle> for this). See the
3226	symbols for more info.	3378	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3379	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3227		3380
3228	The configuration for a "naked" win32 using the microsoft runtime	3381	The configuration for a "naked" win32 using the Microsoft runtime
3229	libraries and raw winsocket select is:	3382	libraries and raw winsocket select is:
3230		3383
3231	#define EV_USE_SELECT 1	3384	#define EV_USE_SELECT 1
3232	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3385	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3233		3386
3234	Note that winsockets handling of fd sets is O(n), so you can easily get a	3387	Note that winsockets handling of fd sets is O(n), so you can easily get a
3235	complexity in the O(n²) range when using win32.	3388	complexity in the O(n²) range when using win32.
3236		3389
3237	=item Limited number of file descriptors	3390	=item Limited number of file descriptors
3238		3391
3239	Windows has numerous arbitrary (and low) limits on things. Early versions	3392	Windows has numerous arbitrary (and low) limits on things.
3240	of winsocket's select only supported waiting for a max. of C<64> handles	3393
		3394	Early versions of winsocket's select only supported waiting for a maximum
3241	(probably owning to the fact that all windows kernels can only wait for	3395	of C<64> handles (probably owning to the fact that all windows kernels
3242	C<64> things at the same time internally; microsoft recommends spawning a	3396	can only wait for C<64> things at the same time internally; Microsoft
3243	chain of threads and wait for 63 handles and the previous thread in each).	3397	recommends spawning a chain of threads and wait for 63 handles and the
		3398	previous thread in each. Great).
3244		3399
3245	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3400	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3246	to some high number (e.g. C<2048>) before compiling the winsocket select	3401	to some high number (e.g. C<2048>) before compiling the winsocket select
3247	call (which might be in libev or elsewhere, for example, perl does its own	3402	call (which might be in libev or elsewhere, for example, perl does its own
3248	select emulation on windows).	3403	select emulation on windows).
3249		3404
3250	Another limit is the number of file descriptors in the microsoft runtime	3405	Another limit is the number of file descriptors in the Microsoft runtime
3251	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3406	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3252	or something like this inside microsoft). You can increase this by calling	3407	or something like this inside Microsoft). You can increase this by calling
3253	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3408	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3254	arbitrary limit), but is broken in many versions of the microsoft runtime	3409	arbitrary limit), but is broken in many versions of the Microsoft runtime
3255	libraries.	3410	libraries.
3256		3411
3257	This might get you to about C<512> or C<2048> sockets (depending on	3412	This might get you to about C<512> or C<2048> sockets (depending on
3258	windows version and/or the phase of the moon). To get more, you need to	3413	windows version and/or the phase of the moon). To get more, you need to
3259	wrap all I/O functions and provide your own fd management, but the cost of	3414	wrap all I/O functions and provide your own fd management, but the cost of
…		…
3266		3421
3267	In addition to a working ISO-C implementation, libev relies on a few	3422	In addition to a working ISO-C implementation, libev relies on a few
3268	additional extensions:	3423	additional extensions:
3269		3424
3270	=over 4	3425	=over 4
		3426
		3427	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3428	calling conventions regardless of C<ev_watcher_type *>.
		3429
		3430	Libev assumes not only that all watcher pointers have the same internal
		3431	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3432	assumes that the same (machine) code can be used to call any watcher
		3433	callback: The watcher callbacks have different type signatures, but libev
		3434	calls them using an C<ev_watcher *> internally.
3271		3435
3272	=item C<sig_atomic_t volatile> must be thread-atomic as well	3436	=item C<sig_atomic_t volatile> must be thread-atomic as well
3273		3437
3274	The type C<sig_atomic_t volatile> (or whatever is defined as	3438	The type C<sig_atomic_t volatile> (or whatever is defined as
3275	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different	3439	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
…		…
3287		3451
3288	The most portable way to handle signals is to block signals in all threads	3452	The most portable way to handle signals is to block signals in all threads
3289	except the initial one, and run the default loop in the initial thread as	3453	except the initial one, and run the default loop in the initial thread as
3290	well.	3454	well.
3291		3455
		3456	=item C<long> must be large enough for common memory allocation sizes
		3457
		3458	To improve portability and simplify using libev, libev uses C<long>
		3459	internally instead of C<size_t> when allocating its data structures. On
		3460	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3461	is still at least 31 bits everywhere, which is enough for hundreds of
		3462	millions of watchers.
		3463
		3464	=item C<double> must hold a time value in seconds with enough accuracy
		3465
		3466	The type C<double> is used to represent timestamps. It is required to
		3467	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3468	enough for at least into the year 4000. This requirement is fulfilled by
		3469	implementations implementing IEEE 754 (basically all existing ones).
		3470
3292	=back	3471	=back
3293		3472
3294	If you know of other additional requirements drop me a note.	3473	If you know of other additional requirements drop me a note.
3295		3474
3296		3475
		3476	=head1 COMPILER WARNINGS
		3477
		3478	Depending on your compiler and compiler settings, you might get no or a
		3479	lot of warnings when compiling libev code. Some people are apparently
		3480	scared by this.
		3481
		3482	However, these are unavoidable for many reasons. For one, each compiler
		3483	has different warnings, and each user has different tastes regarding
		3484	warning options. "Warn-free" code therefore cannot be a goal except when
		3485	targeting a specific compiler and compiler-version.
		3486
		3487	Another reason is that some compiler warnings require elaborate
		3488	workarounds, or other changes to the code that make it less clear and less
		3489	maintainable.
		3490
		3491	And of course, some compiler warnings are just plain stupid, or simply
		3492	wrong (because they don't actually warn about the condition their message
		3493	seems to warn about).
		3494
		3495	While libev is written to generate as few warnings as possible,
		3496	"warn-free" code is not a goal, and it is recommended not to build libev
		3497	with any compiler warnings enabled unless you are prepared to cope with
		3498	them (e.g. by ignoring them). Remember that warnings are just that:
		3499	warnings, not errors, or proof of bugs.
		3500
		3501
		3502	=head1 VALGRIND
		3503
		3504	Valgrind has a special section here because it is a popular tool that is
		3505	highly useful, but valgrind reports are very hard to interpret.
		3506
		3507	If you think you found a bug (memory leak, uninitialised data access etc.)
		3508	in libev, then check twice: If valgrind reports something like:
		3509
		3510	==2274== definitely lost: 0 bytes in 0 blocks.
		3511	==2274== possibly lost: 0 bytes in 0 blocks.
		3512	==2274== still reachable: 256 bytes in 1 blocks.
		3513
		3514	Then there is no memory leak. Similarly, under some circumstances,
		3515	valgrind might report kernel bugs as if it were a bug in libev, or it
		3516	might be confused (it is a very good tool, but only a tool).
		3517
		3518	If you are unsure about something, feel free to contact the mailing list
		3519	with the full valgrind report and an explanation on why you think this is
		3520	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3521	no bug" answer and take the chance of learning how to interpret valgrind
		3522	properly.
		3523
		3524	If you need, for some reason, empty reports from valgrind for your project
		3525	I suggest using suppression lists.
		3526
		3527
3297	=head1 AUTHOR	3528	=head1 AUTHOR
3298		3529
3299	Marc Lehmann <libev@schmorp.de>.	3530	Marc Lehmann <libev@schmorp.de>.
3300		3531

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