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Revision 1.148 by root, Thu Apr 24 01:42:11 2008 UTC vs.
Revision 1.180 by root, Fri Sep 19 03:45:55 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.
		363
		364	This backend maps C<EV_READ> to the C<readfds> set and C<EV_WRITE> to the
		365	C<writefds> set (and to work around Microsoft Windows bugs, also onto the
		366	C<exceptfds> set on that platform).
342		367
343	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	368	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
344		369
345	And this is your standard poll(2) backend. It's more complicated	370	And this is your standard poll(2) backend. It's more complicated
346	than select, but handles sparse fds better and has no artificial	371	than select, but handles sparse fds better and has no artificial
347	limit on the number of fds you can use (except it will slow down	372	limit on the number of fds you can use (except it will slow down
348	considerably with a lot of inactive fds). It scales similarly to select,	373	considerably with a lot of inactive fds). It scales similarly to select,
349	i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for	374	i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for
350	performance tips.	375	performance tips.
351		376
		377	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and
		378	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.
		379
352	=item C<EVBACKEND_EPOLL> (value 4, Linux)	380	=item C<EVBACKEND_EPOLL> (value 4, Linux)
353		381
354	For few fds, this backend is a bit little slower than poll and select,	382	For few fds, this backend is a bit little slower than poll and select,
355	but it scales phenomenally better. While poll and select usually scale	383	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),	384	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	385	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	386	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	387	cases and requiring a system call per fd change, no fork support and bad
360	support for dup.	388	support for dup.
361		389
362	While stopping, setting and starting an I/O watcher in the same iteration	390	While stopping, setting and starting an I/O watcher in the same iteration
363	will result in some caching, there is still a syscall per such incident	391	will result in some caching, there is still a system call per such incident
364	(because the fd could point to a different file description now), so its	392	(because the fd could point to a different file description now), so its
365	best to avoid that. Also, C<dup ()>'ed file descriptors might not work	393	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
366	very well if you register events for both fds.	394	very well if you register events for both fds.
367		395
368	Please note that epoll sometimes generates spurious notifications, so you	396	Please note that epoll sometimes generates spurious notifications, so you
…		…
371		399
372	Best performance from this backend is achieved by not unregistering all	400	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.	401	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.	402	keep at least one watcher active per fd at all times.
375		403
376	While nominally embeddeble in other event loops, this feature is broken in	404	While nominally embeddable in other event loops, this feature is broken in
377	all kernel versions tested so far.	405	all kernel versions tested so far.
		406
		407	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
		408	C<EVBACKEND_POLL>.
378		409
379	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	410	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
380		411
381	Kqueue deserves special mention, as at the time of this writing, it	412	Kqueue deserves special mention, as at the time of this writing, it
382	was broken on all BSDs except NetBSD (usually it doesn't work reliably	413	was broken on all BSDs except NetBSD (usually it doesn't work reliably
383	with anything but sockets and pipes, except on Darwin, where of course	414	with anything but sockets and pipes, except on Darwin, where of course
384	it's completely useless). For this reason it's not being "autodetected"	415	it's completely useless). For this reason it's not being "auto-detected"
385	unless you explicitly specify it explicitly in the flags (i.e. using	416	unless you explicitly specify it explicitly in the flags (i.e. using
386	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)	417	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
387	system like NetBSD.	418	system like NetBSD.
388		419
389	You still can embed kqueue into a normal poll or select backend and use it	420	You still can embed kqueue into a normal poll or select backend and use it
…		…
391	the target platform). See C<ev_embed> watchers for more info.	422	the target platform). See C<ev_embed> watchers for more info.
392		423
393	It scales in the same way as the epoll backend, but the interface to the	424	It scales in the same way as the epoll backend, but the interface to the
394	kernel is more efficient (which says nothing about its actual speed, of	425	kernel is more efficient (which says nothing about its actual speed, of
395	course). While stopping, setting and starting an I/O watcher does never	426	course). While stopping, setting and starting an I/O watcher does never
396	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to	427	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
397	two event changes per incident, support for C<fork ()> is very bad and it	428	two event changes per incident, support for C<fork ()> is very bad and it
398	drops fds silently in similarly hard-to-detect cases.	429	drops fds silently in similarly hard-to-detect cases.
399		430
400	This backend usually performs well under most conditions.	431	This backend usually performs well under most conditions.
401		432
…		…
404	almost everywhere, you should only use it when you have a lot of sockets	435	almost everywhere, you should only use it when you have a lot of sockets
405	(for which it usually works), by embedding it into another event loop	436	(for which it usually works), by embedding it into another event loop
406	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for	437	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for
407	sockets.	438	sockets.
408		439
		440	This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with
		441	C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with
		442	C<NOTE_EOF>.
		443
409	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	444	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
410		445
411	This is not implemented yet (and might never be, unless you send me an	446	This is not implemented yet (and might never be, unless you send me an
412	implementation). According to reports, C</dev/poll> only supports sockets	447	implementation). According to reports, C</dev/poll> only supports sockets
413	and is not embeddable, which would limit the usefulness of this backend	448	and is not embeddable, which would limit the usefulness of this backend
…		…
416	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	451	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
417		452
418	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	453	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
419	it's really slow, but it still scales very well (O(active_fds)).	454	it's really slow, but it still scales very well (O(active_fds)).
420		455
421	Please note that solaris event ports can deliver a lot of spurious	456	Please note that Solaris event ports can deliver a lot of spurious
422	notifications, so you need to use non-blocking I/O or other means to avoid	457	notifications, so you need to use non-blocking I/O or other means to avoid
423	blocking when no data (or space) is available.	458	blocking when no data (or space) is available.
424		459
425	While this backend scales well, it requires one system call per active	460	While this backend scales well, it requires one system call per active
426	file descriptor per loop iteration. For small and medium numbers of file	461	file descriptor per loop iteration. For small and medium numbers of file
427	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	462	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
428	might perform better.	463	might perform better.
429		464
430	On the positive side, ignoring the spurious readyness notifications, this	465	On the positive side, ignoring the spurious readiness notifications, this
431	backend actually performed to specification in all tests and is fully	466	backend actually performed to specification in all tests and is fully
432	embeddable, which is a rare feat among the OS-specific backends.	467	embeddable, which is a rare feat among the OS-specific backends.
		468
		469	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
		470	C<EVBACKEND_POLL>.
433		471
434	=item C<EVBACKEND_ALL>	472	=item C<EVBACKEND_ALL>
435		473
436	Try all backends (even potentially broken ones that wouldn't be tried	474	Try all backends (even potentially broken ones that wouldn't be tried
437	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	475	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
…		…
439		477
440	It is definitely not recommended to use this flag.	478	It is definitely not recommended to use this flag.
441		479
442	=back	480	=back
443		481
444	If one or more of these are ored into the flags value, then only these	482	If one or more of these are or'ed into the flags value, then only these
445	backends will be tried (in the reverse order as listed here). If none are	483	backends will be tried (in the reverse order as listed here). If none are
446	specified, all backends in C<ev_recommended_backends ()> will be tried.	484	specified, all backends in C<ev_recommended_backends ()> will be tried.
447		485
448	The most typical usage is like this:	486	The most typical usage is like this:
449		487
450	if (!ev_default_loop (0))	488	if (!ev_default_loop (0))
451	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	489	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
452		490
453	Restrict libev to the select and poll backends, and do not allow	491	Restrict libev to the select and poll backends, and do not allow
454	environment settings to be taken into account:	492	environment settings to be taken into account:
455		493
456	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);	494	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
457		495
458	Use whatever libev has to offer, but make sure that kqueue is used if	496	Use whatever libev has to offer, but make sure that kqueue is used if
459	available (warning, breaks stuff, best use only with your own private	497	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):	498	event loop and only if you know the OS supports your types of fds):
461		499
462	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	500	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
463		501
464	=item struct ev_loop *ev_loop_new (unsigned int flags)	502	=item struct ev_loop *ev_loop_new (unsigned int flags)
465		503
466	Similar to C<ev_default_loop>, but always creates a new event loop that is	504	Similar to C<ev_default_loop>, but always creates a new event loop that is
467	always distinct from the default loop. Unlike the default loop, it cannot	505	always distinct from the default loop. Unlike the default loop, it cannot
…		…
472	libev with threads is indeed to create one loop per thread, and using the	510	libev with threads is indeed to create one loop per thread, and using the
473	default loop in the "main" or "initial" thread.	511	default loop in the "main" or "initial" thread.
474		512
475	Example: Try to create a event loop that uses epoll and nothing else.	513	Example: Try to create a event loop that uses epoll and nothing else.
476		514
477	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	515	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
478	if (!epoller)	516	if (!epoller)
479	fatal ("no epoll found here, maybe it hides under your chair");	517	fatal ("no epoll found here, maybe it hides under your chair");
480		518
481	=item ev_default_destroy ()	519	=item ev_default_destroy ()
482		520
483	Destroys the default loop again (frees all memory and kernel state	521	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	522	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	523	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>	524	responsibility to either stop all watchers cleanly yourself I<before>
487	calling this function, or cope with the fact afterwards (which is usually	525	calling this function, or cope with the fact afterwards (which is usually
488	the easiest thing, you can just ignore the watchers and/or C<free ()> them	526	the easiest thing, you can just ignore the watchers and/or C<free ()> them
489	for example).	527	for example).
490		528
491	Note that certain global state, such as signal state, will not be freed by	529	Note that certain global state, such as signal state, will not be freed by
…		…
552	received events and started processing them. This timestamp does not	590	received events and started processing them. This timestamp does not
553	change as long as callbacks are being processed, and this is also the base	591	change as long as callbacks are being processed, and this is also the base
554	time used for relative timers. You can treat it as the timestamp of the	592	time used for relative timers. You can treat it as the timestamp of the
555	event occurring (or more correctly, libev finding out about it).	593	event occurring (or more correctly, libev finding out about it).
556		594
		595	=item ev_now_update (loop)
		596
		597	Establishes the current time by querying the kernel, updating the time
		598	returned by C<ev_now ()> in the progress. This is a costly operation and
		599	is usually done automatically within C<ev_loop ()>.
		600
		601	This function is rarely useful, but when some event callback runs for a
		602	very long time without entering the event loop, updating libev's idea of
		603	the current time is a good idea.
		604
		605	See also "The special problem of time updates" in the C<ev_timer> section.
		606
557	=item ev_loop (loop, int flags)	607	=item ev_loop (loop, int flags)
558		608
559	Finally, this is it, the event handler. This function usually is called	609	Finally, this is it, the event handler. This function usually is called
560	after you initialised all your watchers and you want to start handling	610	after you initialised all your watchers and you want to start handling
561	events.	611	events.
…		…
572	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	622	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle
573	those events and any outstanding ones, but will not block your process in	623	those events and any outstanding ones, but will not block your process in
574	case there are no events and will return after one iteration of the loop.	624	case there are no events and will return after one iteration of the loop.
575		625
576	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	626	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
577	neccessary) and will handle those and any outstanding ones. It will block	627	necessary) and will handle those and any outstanding ones. It will block
578	your process until at least one new event arrives, and will return after	628	your process until at least one new event arrives, and will return after
579	one iteration of the loop. This is useful if you are waiting for some	629	one iteration of the loop. This is useful if you are waiting for some
580	external event in conjunction with something not expressible using other	630	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	631	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
582	usually a better approach for this kind of thing.	632	usually a better approach for this kind of thing.
583		633
584	Here are the gory details of what C<ev_loop> does:	634	Here are the gory details of what C<ev_loop> does:
585		635
586	- Before the first iteration, call any pending watchers.	636	- Before the first iteration, call any pending watchers.
587	* If EVFLAG_FORKCHECK was used, check for a fork.	637	* If EVFLAG_FORKCHECK was used, check for a fork.
588	- If a fork was detected, queue and call all fork watchers.	638	- If a fork was detected (by any means), queue and call all fork watchers.
589	- Queue and call all prepare watchers.	639	- Queue and call all prepare watchers.
590	- If we have been forked, recreate the kernel state.	640	- If we have been forked, detach and recreate the kernel state
		641	as to not disturb the other process.
591	- Update the kernel state with all outstanding changes.	642	- Update the kernel state with all outstanding changes.
592	- Update the "event loop time".	643	- Update the "event loop time" (ev_now ()).
593	- Calculate for how long to sleep or block, if at all	644	- Calculate for how long to sleep or block, if at all
594	(active idle watchers, EVLOOP_NONBLOCK or not having	645	(active idle watchers, EVLOOP_NONBLOCK or not having
595	any active watchers at all will result in not sleeping).	646	any active watchers at all will result in not sleeping).
596	- Sleep if the I/O and timer collect interval say so.	647	- Sleep if the I/O and timer collect interval say so.
597	- Block the process, waiting for any events.	648	- Block the process, waiting for any events.
598	- Queue all outstanding I/O (fd) events.	649	- Queue all outstanding I/O (fd) events.
599	- Update the "event loop time" and do time jump handling.	650	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
600	- Queue all outstanding timers.	651	- Queue all outstanding timers.
601	- Queue all outstanding periodics.	652	- Queue all outstanding periodics.
602	- If no events are pending now, queue all idle watchers.	653	- Unless any events are pending now, queue all idle watchers.
603	- Queue all check watchers.	654	- Queue all check watchers.
604	- Call all queued watchers in reverse order (i.e. check watchers first).	655	- Call all queued watchers in reverse order (i.e. check watchers first).
605	Signals and child watchers are implemented as I/O watchers, and will	656	Signals and child watchers are implemented as I/O watchers, and will
606	be handled here by queueing them when their watcher gets executed.	657	be handled here by queueing them when their watcher gets executed.
607	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	658	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
…		…
612	anymore.	663	anymore.
613		664
614	... queue jobs here, make sure they register event watchers as long	665	... 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..)	666	... as they still have work to do (even an idle watcher will do..)
616	ev_loop (my_loop, 0);	667	ev_loop (my_loop, 0);
617	... jobs done. yeah!	668	... jobs done or somebody called unloop. yeah!
618		669
619	=item ev_unloop (loop, how)	670	=item ev_unloop (loop, how)
620		671
621	Can be used to make a call to C<ev_loop> return early (but only after it	672	Can be used to make a call to C<ev_loop> return early (but only after it
622	has processed all outstanding events). The C<how> argument must be either	673	has processed all outstanding events). The C<how> argument must be either
…		…
643	respectively).	694	respectively).
644		695
645	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	696	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
646	running when nothing else is active.	697	running when nothing else is active.
647		698
648	struct ev_signal exitsig;	699	struct ev_signal exitsig;
649	ev_signal_init (&exitsig, sig_cb, SIGINT);	700	ev_signal_init (&exitsig, sig_cb, SIGINT);
650	ev_signal_start (loop, &exitsig);	701	ev_signal_start (loop, &exitsig);
651	evf_unref (loop);	702	evf_unref (loop);
652		703
653	Example: For some weird reason, unregister the above signal handler again.	704	Example: For some weird reason, unregister the above signal handler again.
654		705
655	ev_ref (loop);	706	ev_ref (loop);
656	ev_signal_stop (loop, &exitsig);	707	ev_signal_stop (loop, &exitsig);
657		708
658	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	709	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
659		710
660	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	711	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
661		712
662	These advanced functions influence the time that libev will spend waiting	713	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	714	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.	715	will try to invoke timer/periodic callbacks and I/O callbacks with minimum
		716	latency.
665		717
666	Setting these to a higher value (the C<interval> I<must> be >= C<0>)	718	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
667	allows libev to delay invocation of I/O and timer/periodic callbacks to	719	allows libev to delay invocation of I/O and timer/periodic callbacks
668	increase efficiency of loop iterations.	720	to increase efficiency of loop iterations (or to increase power-saving
		721	opportunities).
669		722
670	The background is that sometimes your program runs just fast enough to	723	The background is that sometimes your program runs just fast enough to
671	handle one (or very few) event(s) per loop iteration. While this makes	724	handle one (or very few) event(s) per loop iteration. While this makes
672	the program responsive, it also wastes a lot of CPU time to poll for new	725	the program responsive, it also wastes a lot of CPU time to poll for new
673	events, especially with backends like C<select ()> which have a high	726	events, especially with backends like C<select ()> which have a high
…		…
683	to spend more time collecting timeouts, at the expense of increased	736	to spend more time collecting timeouts, at the expense of increased
684	latency (the watcher callback will be called later). C<ev_io> watchers	737	latency (the watcher callback will be called later). C<ev_io> watchers
685	will not be affected. Setting this to a non-null value will not introduce	738	will not be affected. Setting this to a non-null value will not introduce
686	any overhead in libev.	739	any overhead in libev.
687		740
688	Many (busy) programs can usually benefit by setting the io collect	741	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	742	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	743	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>,	744	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.	745	as this approaches the timing granularity of most systems.
		746
		747	Setting the I<timeout collect interval> can improve the opportunity for
		748	saving power, as the program will "bundle" timer callback invocations that
		749	are "near" in time together, by delaying some, thus reducing the number of
		750	times the process sleeps and wakes up again. Another useful technique to
		751	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
		752	they fire on, say, one-second boundaries only.
		753
		754	=item ev_loop_verify (loop)
		755
		756	This function only does something when C<EV_VERIFY> support has been
		757	compiled in. It tries to go through all internal structures and checks
		758	them for validity. If anything is found to be inconsistent, it will print
		759	an error message to standard error and call C<abort ()>.
		760
		761	This can be used to catch bugs inside libev itself: under normal
		762	circumstances, this function will never abort as of course libev keeps its
		763	data structures consistent.
693		764
694	=back	765	=back
695		766
696		767
697	=head1 ANATOMY OF A WATCHER	768	=head1 ANATOMY OF A WATCHER
698		769
699	A watcher is a structure that you create and register to record your	770	A watcher is a structure that you create and register to record your
700	interest in some event. For instance, if you want to wait for STDIN to	771	interest in some event. For instance, if you want to wait for STDIN to
701	become readable, you would create an C<ev_io> watcher for that:	772	become readable, you would create an C<ev_io> watcher for that:
702		773
703	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	774	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
704	{	775	{
705	ev_io_stop (w);	776	ev_io_stop (w);
706	ev_unloop (loop, EVUNLOOP_ALL);	777	ev_unloop (loop, EVUNLOOP_ALL);
707	}	778	}
708		779
709	struct ev_loop *loop = ev_default_loop (0);	780	struct ev_loop *loop = ev_default_loop (0);
710	struct ev_io stdin_watcher;	781	struct ev_io stdin_watcher;
711	ev_init (&stdin_watcher, my_cb);	782	ev_init (&stdin_watcher, my_cb);
712	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	783	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
713	ev_io_start (loop, &stdin_watcher);	784	ev_io_start (loop, &stdin_watcher);
714	ev_loop (loop, 0);	785	ev_loop (loop, 0);
715		786
716	As you can see, you are responsible for allocating the memory for your	787	As you can see, you are responsible for allocating the memory for your
717	watcher structures (and it is usually a bad idea to do this on the stack,	788	watcher structures (and it is usually a bad idea to do this on the stack,
718	although this can sometimes be quite valid).	789	although this can sometimes be quite valid).
719		790
720	Each watcher structure must be initialised by a call to C<ev_init	791	Each watcher structure must be initialised by a call to C<ev_init
721	(watcher *, callback)>, which expects a callback to be provided. This	792	(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	793	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	794	watchers, each time the event loop detects that the file descriptor given
724	is readable and/or writable).	795	is readable and/or writable).
725		796
726	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	797	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro
727	with arguments specific to this watcher type. There is also a macro	798	with arguments specific to this watcher type. There is also a macro
…		…
803		874
804	The given async watcher has been asynchronously notified (see C<ev_async>).	875	The given async watcher has been asynchronously notified (see C<ev_async>).
805		876
806	=item C<EV_ERROR>	877	=item C<EV_ERROR>
807		878
808	An unspecified error has occured, the watcher has been stopped. This might	879	An unspecified error has occurred, the watcher has been stopped. This might
809	happen because the watcher could not be properly started because libev	880	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	881	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	882	problem. You best act on it by reporting the problem and somehow coping
812	with the watcher being stopped.	883	with the watcher being stopped.
813		884
814	Libev will usually signal a few "dummy" events together with an error,	885	Libev will usually signal a few "dummy" events together with an error,
815	for example it might indicate that a fd is readable or writable, and if	886	for example it might indicate that a fd is readable or writable, and if
816	your callbacks is well-written it can just attempt the operation and cope	887	your callbacks is well-written it can just attempt the operation and cope
817	with the error from read() or write(). This will not work in multithreaded	888	with the error from read() or write(). This will not work in multi-threaded
818	programs, though, so beware.	889	programs, though, so beware.
819		890
820	=back	891	=back
821		892
822	=head2 GENERIC WATCHER FUNCTIONS	893	=head2 GENERIC WATCHER FUNCTIONS
…		…
852	Although some watcher types do not have type-specific arguments	923	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.	924	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
854		925
855	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	926	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
856		927
857	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	928	This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
858	calls into a single call. This is the most convinient method to initialise	929	calls into a single call. This is the most convenient method to initialise
859	a watcher. The same limitations apply, of course.	930	a watcher. The same limitations apply, of course.
860		931
861	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	932	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
862		933
863	Starts (activates) the given watcher. Only active watchers will receive	934	Starts (activates) the given watcher. Only active watchers will receive
…		…
946	to associate arbitrary data with your watcher. If you need more data and	1017	to associate arbitrary data with your watcher. If you need more data and
947	don't want to allocate memory and store a pointer to it in that data	1018	don't want to allocate memory and store a pointer to it in that data
948	member, you can also "subclass" the watcher type and provide your own	1019	member, you can also "subclass" the watcher type and provide your own
949	data:	1020	data:
950		1021
951	struct my_io	1022	struct my_io
952	{	1023	{
953	struct ev_io io;	1024	struct ev_io io;
954	int otherfd;	1025	int otherfd;
955	void *somedata;	1026	void *somedata;
956	struct whatever *mostinteresting;	1027	struct whatever *mostinteresting;
957	}	1028	};
		1029
		1030	...
		1031	struct my_io w;
		1032	ev_io_init (&w.io, my_cb, fd, EV_READ);
958		1033
959	And since your callback will be called with a pointer to the watcher, you	1034	And since your callback will be called with a pointer to the watcher, you
960	can cast it back to your own type:	1035	can cast it back to your own type:
961		1036
962	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	1037	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
963	{	1038	{
964	struct my_io *w = (struct my_io *)w_;	1039	struct my_io *w = (struct my_io *)w_;
965	...	1040	...
966	}	1041	}
967		1042
968	More interesting and less C-conformant ways of casting your callback type	1043	More interesting and less C-conformant ways of casting your callback type
969	instead have been omitted.	1044	instead have been omitted.
970		1045
971	Another common scenario is having some data structure with multiple	1046	Another common scenario is to use some data structure with multiple
972	watchers:	1047	embedded watchers:
973		1048
974	struct my_biggy	1049	struct my_biggy
975	{	1050	{
976	int some_data;	1051	int some_data;
977	ev_timer t1;	1052	ev_timer t1;
978	ev_timer t2;	1053	ev_timer t2;
979	}	1054	}
980		1055
981	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1056	In this case getting the pointer to C<my_biggy> is a bit more
982	you need to use C<offsetof>:	1057	complicated: Either you store the address of your C<my_biggy> struct
		1058	in the C<data> member of the watcher, or you need to use some pointer
		1059	arithmetic using C<offsetof> inside your watchers:
983		1060
984	#include <stddef.h>	1061	#include <stddef.h>
985		1062
986	static void	1063	static void
987	t1_cb (EV_P_ struct ev_timer *w, int revents)	1064	t1_cb (EV_P_ struct ev_timer *w, int revents)
988	{	1065	{
989	struct my_biggy big = (struct my_biggy *	1066	struct my_biggy big = (struct my_biggy *
990	(((char *)w) - offsetof (struct my_biggy, t1));	1067	(((char *)w) - offsetof (struct my_biggy, t1));
991	}	1068	}
992		1069
993	static void	1070	static void
994	t2_cb (EV_P_ struct ev_timer *w, int revents)	1071	t2_cb (EV_P_ struct ev_timer *w, int revents)
995	{	1072	{
996	struct my_biggy big = (struct my_biggy *	1073	struct my_biggy big = (struct my_biggy *
997	(((char *)w) - offsetof (struct my_biggy, t2));	1074	(((char *)w) - offsetof (struct my_biggy, t2));
998	}	1075	}
999		1076
1000		1077
1001	=head1 WATCHER TYPES	1078	=head1 WATCHER TYPES
1002		1079
1003	This section describes each watcher in detail, but will not repeat	1080	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	1109	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	1110	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
1034	C<EVBACKEND_POLL>).	1111	C<EVBACKEND_POLL>).
1035		1112
1036	Another thing you have to watch out for is that it is quite easy to	1113	Another thing you have to watch out for is that it is quite easy to
1037	receive "spurious" readyness notifications, that is your callback might	1114	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	1115	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	1116	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	1117	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	1118	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	1119	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.	1120	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1044		1121
1045	If you cannot run the fd in non-blocking mode (for example you should not	1122	If you cannot run the fd in non-blocking mode (for example you should not
1046	play around with an Xlib connection), then you have to seperately re-test	1123	play around with an Xlib connection), then you have to separately re-test
1047	whether a file descriptor is really ready with a known-to-be good interface	1124	whether a file descriptor is really ready with a known-to-be good interface
1048	such as poll (fortunately in our Xlib example, Xlib already does this on	1125	such as poll (fortunately in our Xlib example, Xlib already does this on
1049	its own, so its quite safe to use).	1126	its own, so its quite safe to use).
1050		1127
1051	=head3 The special problem of disappearing file descriptors	1128	=head3 The special problem of disappearing file descriptors
…		…
1092	C<EVBACKEND_POLL>.	1169	C<EVBACKEND_POLL>.
1093		1170
1094	=head3 The special problem of SIGPIPE	1171	=head3 The special problem of SIGPIPE
1095		1172
1096	While not really specific to libev, it is easy to forget about SIGPIPE:	1173	While not really specific to libev, it is easy to forget about SIGPIPE:
1097	when reading from a pipe whose other end has been closed, your program	1174	when writing to a pipe whose other end has been closed, your program gets
1098	gets send a SIGPIPE, which, by default, aborts your program. For most	1175	send a SIGPIPE, which, by default, aborts your program. For most programs
1099	programs this is sensible behaviour, for daemons, this is usually	1176	this is sensible behaviour, for daemons, this is usually undesirable.
1100	undesirable.
1101		1177
1102	So when you encounter spurious, unexplained daemon exits, make sure you	1178	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	1179	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).	1180	somewhere, as that would have given you a big clue).
1105		1181
…		…
1111	=item ev_io_init (ev_io *, callback, int fd, int events)	1187	=item ev_io_init (ev_io *, callback, int fd, int events)
1112		1188
1113	=item ev_io_set (ev_io *, int fd, int events)	1189	=item ev_io_set (ev_io *, int fd, int events)
1114		1190
1115	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1191	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1116	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1192	receive events for and events is either C<EV_READ>, C<EV_WRITE> or
1117	C<EV_READ | EV_WRITE> to receive the given events.	1193	C<EV_READ | EV_WRITE> to receive the given events.
1118		1194
1119	=item int fd [read-only]	1195	=item int fd [read-only]
1120		1196
1121	The file descriptor being watched.	1197	The file descriptor being watched.
…		…
1130		1206
1131	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1207	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1132	readable, but only once. Since it is likely line-buffered, you could	1208	readable, but only once. Since it is likely line-buffered, you could
1133	attempt to read a whole line in the callback.	1209	attempt to read a whole line in the callback.
1134		1210
1135	static void	1211	static void
1136	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1212	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1137	{	1213	{
1138	ev_io_stop (loop, w);	1214	ev_io_stop (loop, w);
1139	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1215	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1140	}	1216	}
1141		1217
1142	...	1218	...
1143	struct ev_loop *loop = ev_default_init (0);	1219	struct ev_loop *loop = ev_default_init (0);
1144	struct ev_io stdin_readable;	1220	struct ev_io stdin_readable;
1145	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1221	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1146	ev_io_start (loop, &stdin_readable);	1222	ev_io_start (loop, &stdin_readable);
1147	ev_loop (loop, 0);	1223	ev_loop (loop, 0);
1148		1224
1149		1225
1150	=head2 C<ev_timer> - relative and optionally repeating timeouts	1226	=head2 C<ev_timer> - relative and optionally repeating timeouts
1151		1227
1152	Timer watchers are simple relative timers that generate an event after a	1228	Timer watchers are simple relative timers that generate an event after a
1153	given time, and optionally repeating in regular intervals after that.	1229	given time, and optionally repeating in regular intervals after that.
1154		1230
1155	The timers are based on real time, that is, if you register an event that	1231	The timers are based on real time, that is, if you register an event that
1156	times out after an hour and you reset your system clock to last years	1232	times out after an hour and you reset your system clock to January last
1157	time, it will still time out after (roughly) and hour. "Roughly" because	1233	year, it will still time out after (roughly) and hour. "Roughly" because
1158	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1234	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1159	monotonic clock option helps a lot here).	1235	monotonic clock option helps a lot here).
		1236
		1237	The callback is guaranteed to be invoked only after its timeout has passed,
		1238	but if multiple timers become ready during the same loop iteration then
		1239	order of execution is undefined.
		1240
		1241	=head3 The special problem of time updates
		1242
		1243	Establishing the current time is a costly operation (it usually takes at
		1244	least two system calls): EV therefore updates its idea of the current
		1245	time only before and after C<ev_loop> polls for new events, which causes
		1246	a growing difference between C<ev_now ()> and C<ev_time ()> when handling
		1247	lots of events.
1160		1248
1161	The relative timeouts are calculated relative to the C<ev_now ()>	1249	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	1250	time. This is usually the right thing as this timestamp refers to the time
1163	of the event triggering whatever timeout you are modifying/starting. If	1251	of the event triggering whatever timeout you are modifying/starting. If
1164	you suspect event processing to be delayed and you I<need> to base the timeout	1252	you suspect event processing to be delayed and you I<need> to base the
1165	on the current time, use something like this to adjust for this:	1253	timeout on the current time, use something like this to adjust for this:
1166		1254
1167	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1255	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1168		1256
1169	The callback is guarenteed to be invoked only when its timeout has passed,	1257	If the event loop is suspended for a long time, you can also force an
1170	but if multiple timers become ready during the same loop iteration then	1258	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1171	order of execution is undefined.	1259	()>.
1172		1260
1173	=head3 Watcher-Specific Functions and Data Members	1261	=head3 Watcher-Specific Functions and Data Members
1174		1262
1175	=over 4	1263	=over 4
1176		1264
1177	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1265	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1178		1266
1179	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1267	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1180		1268
1181	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1269	Configure the timer to trigger after C<after> seconds. If C<repeat>
1182	C<0.>, then it will automatically be stopped. If it is positive, then the	1270	is C<0.>, then it will automatically be stopped once the timeout is
1183	timer will automatically be configured to trigger again C<repeat> seconds	1271	reached. If it is positive, then the timer will automatically be
1184	later, again, and again, until stopped manually.	1272	configured to trigger again C<repeat> seconds later, again, and again,
		1273	until stopped manually.
1185		1274
1186	The timer itself will do a best-effort at avoiding drift, that is, if you	1275	The timer itself will do a best-effort at avoiding drift, that is, if
1187	configure a timer to trigger every 10 seconds, then it will trigger at	1276	you configure a timer to trigger every 10 seconds, then it will normally
1188	exactly 10 second intervals. If, however, your program cannot keep up with	1277	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	1278	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.	1279	do stuff) the timer will not fire more than once per event loop iteration.
1191		1280
1192	=item ev_timer_again (loop, ev_timer *)	1281	=item ev_timer_again (loop, ev_timer *)
1193		1282
1194	This will act as if the timer timed out and restart it again if it is	1283	This will act as if the timer timed out and restart it again if it is
1195	repeating. The exact semantics are:	1284	repeating. The exact semantics are:
1196		1285
1197	If the timer is pending, its pending status is cleared.	1286	If the timer is pending, its pending status is cleared.
1198		1287
1199	If the timer is started but nonrepeating, stop it (as if it timed out).	1288	If the timer is started but non-repeating, stop it (as if it timed out).
1200		1289
1201	If the timer is repeating, either start it if necessary (with the	1290	If the timer is repeating, either start it if necessary (with the
1202	C<repeat> value), or reset the running timer to the C<repeat> value.	1291	C<repeat> value), or reset the running timer to the C<repeat> value.
1203		1292
1204	This sounds a bit complicated, but here is a useful and typical	1293	This sounds a bit complicated, but here is a useful and typical
1205	example: Imagine you have a tcp connection and you want a so-called idle	1294	example: Imagine you have a TCP connection and you want a so-called idle
1206	timeout, that is, you want to be called when there have been, say, 60	1295	timeout, that is, you want to be called when there have been, say, 60
1207	seconds of inactivity on the socket. The easiest way to do this is to	1296	seconds of inactivity on the socket. The easiest way to do this is to
1208	configure an C<ev_timer> with a C<repeat> value of C<60> and then call	1297	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1209	C<ev_timer_again> each time you successfully read or write some data. If	1298	C<ev_timer_again> each time you successfully read or write some data. If
1210	you go into an idle state where you do not expect data to travel on the	1299	you go into an idle state where you do not expect data to travel on the
…		…
1236		1325
1237	=head3 Examples	1326	=head3 Examples
1238		1327
1239	Example: Create a timer that fires after 60 seconds.	1328	Example: Create a timer that fires after 60 seconds.
1240		1329
1241	static void	1330	static void
1242	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1331	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1243	{	1332	{
1244	.. one minute over, w is actually stopped right here	1333	.. one minute over, w is actually stopped right here
1245	}	1334	}
1246		1335
1247	struct ev_timer mytimer;	1336	struct ev_timer mytimer;
1248	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1337	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1249	ev_timer_start (loop, &mytimer);	1338	ev_timer_start (loop, &mytimer);
1250		1339
1251	Example: Create a timeout timer that times out after 10 seconds of	1340	Example: Create a timeout timer that times out after 10 seconds of
1252	inactivity.	1341	inactivity.
1253		1342
1254	static void	1343	static void
1255	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1344	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1256	{	1345	{
1257	.. ten seconds without any activity	1346	.. ten seconds without any activity
1258	}	1347	}
1259		1348
1260	struct ev_timer mytimer;	1349	struct ev_timer mytimer;
1261	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1350	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1262	ev_timer_again (&mytimer); /* start timer */	1351	ev_timer_again (&mytimer); /* start timer */
1263	ev_loop (loop, 0);	1352	ev_loop (loop, 0);
1264		1353
1265	// and in some piece of code that gets executed on any "activity":	1354	// and in some piece of code that gets executed on any "activity":
1266	// reset the timeout to start ticking again at 10 seconds	1355	// reset the timeout to start ticking again at 10 seconds
1267	ev_timer_again (&mytimer);	1356	ev_timer_again (&mytimer);
1268		1357
1269		1358
1270	=head2 C<ev_periodic> - to cron or not to cron?	1359	=head2 C<ev_periodic> - to cron or not to cron?
1271		1360
1272	Periodic watchers are also timers of a kind, but they are very versatile	1361	Periodic watchers are also timers of a kind, but they are very versatile
1273	(and unfortunately a bit complex).	1362	(and unfortunately a bit complex).
1274		1363
1275	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1364	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
1276	but on wallclock time (absolute time). You can tell a periodic watcher	1365	but on wall clock time (absolute time). You can tell a periodic watcher
1277	to trigger "at" some specific point in time. For example, if you tell a	1366	to trigger after some specific point in time. For example, if you tell a
1278	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1367	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()
1279	+ 10.>) and then reset your system clock to the last year, then it will	1368	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1369	clock to January of the previous year, then it will take more than year
1280	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1370	to trigger the event (unlike an C<ev_timer>, which would still trigger
1281	roughly 10 seconds later).	1371	roughly 10 seconds later as it uses a relative timeout).
1282		1372
1283	They can also be used to implement vastly more complex timers, such as	1373	C<ev_periodic>s can also be used to implement vastly more complex timers,
1284	triggering an event on each midnight, local time or other, complicated,	1374	such as triggering an event on each "midnight, local time", or other
1285	rules.	1375	complicated, rules.
1286		1376
1287	As with timers, the callback is guarenteed to be invoked only when the	1377	As with timers, the callback is guaranteed to be invoked only when the
1288	time (C<at>) has been passed, but if multiple periodic timers become ready	1378	time (C<at>) has passed, but if multiple periodic timers become ready
1289	during the same loop iteration then order of execution is undefined.	1379	during the same loop iteration then order of execution is undefined.
1290		1380
1291	=head3 Watcher-Specific Functions and Data Members	1381	=head3 Watcher-Specific Functions and Data Members
1292		1382
1293	=over 4	1383	=over 4
…		…
1301		1391
1302	=over 4	1392	=over 4
1303		1393
1304	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1394	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1305		1395
1306	In this configuration the watcher triggers an event at the wallclock time	1396	In this configuration the watcher triggers an event after the wall clock
1307	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1397	time C<at> has passed and doesn't repeat. It will not adjust when a time
1308	that is, if it is to be run at January 1st 2011 then it will run when the	1398	jump occurs, that is, if it is to be run at January 1st 2011 then it will
1309	system time reaches or surpasses this time.	1399	run when the system time reaches or surpasses this time.
1310		1400
1311	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1401	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1312		1402
1313	In this mode the watcher will always be scheduled to time out at the next	1403	In this mode the watcher will always be scheduled to time out at the next
1314	C<at + N * interval> time (for some integer N, which can also be negative)	1404	C<at + N * interval> time (for some integer N, which can also be negative)
1315	and then repeat, regardless of any time jumps.	1405	and then repeat, regardless of any time jumps.
1316		1406
1317	This can be used to create timers that do not drift with respect to system	1407	This can be used to create timers that do not drift with respect to system
1318	time:	1408	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1409	the hour:
1319		1410
1320	ev_periodic_set (&periodic, 0., 3600., 0);	1411	ev_periodic_set (&periodic, 0., 3600., 0);
1321		1412
1322	This doesn't mean there will always be 3600 seconds in between triggers,	1413	This doesn't mean there will always be 3600 seconds in between triggers,
1323	but only that the the callback will be called when the system time shows a	1414	but only that the callback will be called when the system time shows a
1324	full hour (UTC), or more correctly, when the system time is evenly divisible	1415	full hour (UTC), or more correctly, when the system time is evenly divisible
1325	by 3600.	1416	by 3600.
1326		1417
1327	Another way to think about it (for the mathematically inclined) is that	1418	Another way to think about it (for the mathematically inclined) is that
1328	C<ev_periodic> will try to run the callback in this mode at the next possible	1419	C<ev_periodic> will try to run the callback in this mode at the next possible
1329	time where C<time = at (mod interval)>, regardless of any time jumps.	1420	time where C<time = at (mod interval)>, regardless of any time jumps.
1330		1421
1331	For numerical stability it is preferable that the C<at> value is near	1422	For numerical stability it is preferable that the C<at> value is near
1332	C<ev_now ()> (the current time), but there is no range requirement for	1423	C<ev_now ()> (the current time), but there is no range requirement for
1333	this value.	1424	this value, and in fact is often specified as zero.
		1425
		1426	Note also that there is an upper limit to how often a timer can fire (CPU
		1427	speed for example), so if C<interval> is very small then timing stability
		1428	will of course deteriorate. Libev itself tries to be exact to be about one
		1429	millisecond (if the OS supports it and the machine is fast enough).
1334		1430
1335	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1431	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1336		1432
1337	In this mode the values for C<interval> and C<at> are both being	1433	In this mode the values for C<interval> and C<at> are both being
1338	ignored. Instead, each time the periodic watcher gets scheduled, the	1434	ignored. Instead, each time the periodic watcher gets scheduled, the
1339	reschedule callback will be called with the watcher as first, and the	1435	reschedule callback will be called with the watcher as first, and the
1340	current time as second argument.	1436	current time as second argument.
1341		1437
1342	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1438	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1343	ever, or make any event loop modifications>. If you need to stop it,	1439	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		1440
		1441	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1442	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1443	only event loop modification you are allowed to do).
		1444
1347	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1445	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1348	ev_tstamp now)>, e.g.:	1446	*w, ev_tstamp now)>, e.g.:
1349		1447
1350	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1448	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1351	{	1449	{
1352	return now + 60.;	1450	return now + 60.;
1353	}	1451	}
…		…
1355	It must return the next time to trigger, based on the passed time value	1453	It must return the next time to trigger, based on the passed time value
1356	(that is, the lowest time value larger than to the second argument). It	1454	(that is, the lowest time value larger than to the second argument). It
1357	will usually be called just before the callback will be triggered, but	1455	will usually be called just before the callback will be triggered, but
1358	might be called at other times, too.	1456	might be called at other times, too.
1359		1457
1360	NOTE: I<< This callback must always return a time that is later than the	1458	NOTE: I<< This callback must always return a time that is higher than or
1361	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.	1459	equal to the passed C<now> value >>.
1362		1460
1363	This can be used to create very complex timers, such as a timer that	1461	This can be used to create very complex timers, such as a timer that
1364	triggers on each midnight, local time. To do this, you would calculate the	1462	triggers on "next midnight, local time". To do this, you would calculate the
1365	next midnight after C<now> and return the timestamp value for this. How	1463	next midnight after C<now> and return the timestamp value for this. How
1366	you do this is, again, up to you (but it is not trivial, which is the main	1464	you do this is, again, up to you (but it is not trivial, which is the main
1367	reason I omitted it as an example).	1465	reason I omitted it as an example).
1368		1466
1369	=back	1467	=back
…		…
1373	Simply stops and restarts the periodic watcher again. This is only useful	1471	Simply stops and restarts the periodic watcher again. This is only useful
1374	when you changed some parameters or the reschedule callback would return	1472	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	1473	a different time than the last time it was called (e.g. in a crond like
1376	program when the crontabs have changed).	1474	program when the crontabs have changed).
1377		1475
		1476	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1477
		1478	When active, returns the absolute time that the watcher is supposed to
		1479	trigger next.
		1480
1378	=item ev_tstamp offset [read-write]	1481	=item ev_tstamp offset [read-write]
1379		1482
1380	When repeating, this contains the offset value, otherwise this is the	1483	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>).	1484	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1382		1485
…		…
1393		1496
1394	The current reschedule callback, or C<0>, if this functionality is	1497	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	1498	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.	1499	the periodic timer fires or C<ev_periodic_again> is being called.
1397		1500
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	1501	=back
1404		1502
1405	=head3 Examples	1503	=head3 Examples
1406		1504
1407	Example: Call a callback every hour, or, more precisely, whenever the	1505	Example: Call a callback every hour, or, more precisely, whenever the
1408	system clock is divisible by 3600. The callback invocation times have	1506	system clock is divisible by 3600. The callback invocation times have
1409	potentially a lot of jittering, but good long-term stability.	1507	potentially a lot of jitter, but good long-term stability.
1410		1508
1411	static void	1509	static void
1412	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1510	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1413	{	1511	{
1414	... its now a full hour (UTC, or TAI or whatever your clock follows)	1512	... its now a full hour (UTC, or TAI or whatever your clock follows)
1415	}	1513	}
1416		1514
1417	struct ev_periodic hourly_tick;	1515	struct ev_periodic hourly_tick;
1418	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1516	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1419	ev_periodic_start (loop, &hourly_tick);	1517	ev_periodic_start (loop, &hourly_tick);
1420		1518
1421	Example: The same as above, but use a reschedule callback to do it:	1519	Example: The same as above, but use a reschedule callback to do it:
1422		1520
1423	#include <math.h>	1521	#include <math.h>
1424		1522
1425	static ev_tstamp	1523	static ev_tstamp
1426	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1524	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1427	{	1525	{
1428	return fmod (now, 3600.) + 3600.;	1526	return fmod (now, 3600.) + 3600.;
1429	}	1527	}
1430		1528
1431	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1529	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1432		1530
1433	Example: Call a callback every hour, starting now:	1531	Example: Call a callback every hour, starting now:
1434		1532
1435	struct ev_periodic hourly_tick;	1533	struct ev_periodic hourly_tick;
1436	ev_periodic_init (&hourly_tick, clock_cb,	1534	ev_periodic_init (&hourly_tick, clock_cb,
1437	fmod (ev_now (loop), 3600.), 3600., 0);	1535	fmod (ev_now (loop), 3600.), 3600., 0);
1438	ev_periodic_start (loop, &hourly_tick);	1536	ev_periodic_start (loop, &hourly_tick);
1439		1537
1440		1538
1441	=head2 C<ev_signal> - signal me when a signal gets signalled!	1539	=head2 C<ev_signal> - signal me when a signal gets signalled!
1442		1540
1443	Signal watchers will trigger an event when the process receives a specific	1541	Signal watchers will trigger an event when the process receives a specific
…		…
1451	as you don't register any with libev). Similarly, when the last signal	1549	as you don't register any with libev). Similarly, when the last signal
1452	watcher for a signal is stopped libev will reset the signal handler to	1550	watcher for a signal is stopped libev will reset the signal handler to
1453	SIG_DFL (regardless of what it was set to before).	1551	SIG_DFL (regardless of what it was set to before).
1454		1552
1455	If possible and supported, libev will install its handlers with	1553	If possible and supported, libev will install its handlers with
1456	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1554	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1457	interrupted. If you have a problem with syscalls getting interrupted by	1555	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	1556	signals you can block all signals in an C<ev_check> watcher and unblock
1459	them in an C<ev_prepare> watcher.	1557	them in an C<ev_prepare> watcher.
1460		1558
1461	=head3 Watcher-Specific Functions and Data Members	1559	=head3 Watcher-Specific Functions and Data Members
1462		1560
…		…
1477		1575
1478	=head3 Examples	1576	=head3 Examples
1479		1577
1480	Example: Try to exit cleanly on SIGINT and SIGTERM.	1578	Example: Try to exit cleanly on SIGINT and SIGTERM.
1481		1579
1482	static void	1580	static void
1483	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1581	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1484	{	1582	{
1485	ev_unloop (loop, EVUNLOOP_ALL);	1583	ev_unloop (loop, EVUNLOOP_ALL);
1486	}	1584	}
1487		1585
1488	struct ev_signal signal_watcher;	1586	struct ev_signal signal_watcher;
1489	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1587	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1490	ev_signal_start (loop, &sigint_cb);	1588	ev_signal_start (loop, &sigint_cb);
1491		1589
1492		1590
1493	=head2 C<ev_child> - watch out for process status changes	1591	=head2 C<ev_child> - watch out for process status changes
1494		1592
1495	Child watchers trigger when your process receives a SIGCHLD in response to	1593	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1497	is permissible to install a child watcher I<after> the child has been	1595	is permissible to install a child watcher I<after> the child has been
1498	forked (which implies it might have already exited), as long as the event	1596	forked (which implies it might have already exited), as long as the event
1499	loop isn't entered (or is continued from a watcher).	1597	loop isn't entered (or is continued from a watcher).
1500		1598
1501	Only the default event loop is capable of handling signals, and therefore	1599	Only the default event loop is capable of handling signals, and therefore
1502	you can only rgeister child watchers in the default event loop.	1600	you can only register child watchers in the default event loop.
1503		1601
1504	=head3 Process Interaction	1602	=head3 Process Interaction
1505		1603
1506	Libev grabs C<SIGCHLD> as soon as the default event loop is	1604	Libev grabs C<SIGCHLD> as soon as the default event loop is
1507	initialised. This is necessary to guarantee proper behaviour even if	1605	initialised. This is necessary to guarantee proper behaviour even if
1508	the first child watcher is started after the child exits. The occurance	1606	the first child watcher is started after the child exits. The occurrence
1509	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1607	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1510	synchronously as part of the event loop processing. Libev always reaps all	1608	synchronously as part of the event loop processing. Libev always reaps all
1511	children, even ones not watched.	1609	children, even ones not watched.
1512		1610
1513	=head3 Overriding the Built-In Processing	1611	=head3 Overriding the Built-In Processing
…		…
1517	handler, you can override it easily by installing your own handler for	1615	handler, you can override it easily by installing your own handler for
1518	C<SIGCHLD> after initialising the default loop, and making sure the	1616	C<SIGCHLD> after initialising the default loop, and making sure the
1519	default loop never gets destroyed. You are encouraged, however, to use an	1617	default loop never gets destroyed. You are encouraged, however, to use an
1520	event-based approach to child reaping and thus use libev's support for	1618	event-based approach to child reaping and thus use libev's support for
1521	that, so other libev users can use C<ev_child> watchers freely.	1619	that, so other libev users can use C<ev_child> watchers freely.
		1620
		1621	=head3 Stopping the Child Watcher
		1622
		1623	Currently, the child watcher never gets stopped, even when the
		1624	child terminates, so normally one needs to stop the watcher in the
		1625	callback. Future versions of libev might stop the watcher automatically
		1626	when a child exit is detected.
1522		1627
1523	=head3 Watcher-Specific Functions and Data Members	1628	=head3 Watcher-Specific Functions and Data Members
1524		1629
1525	=over 4	1630	=over 4
1526		1631
…		…
1555	=head3 Examples	1660	=head3 Examples
1556		1661
1557	Example: C<fork()> a new process and install a child handler to wait for	1662	Example: C<fork()> a new process and install a child handler to wait for
1558	its completion.	1663	its completion.
1559		1664
1560	ev_child cw;	1665	ev_child cw;
1561		1666
1562	static void	1667	static void
1563	child_cb (EV_P_ struct ev_child *w, int revents)	1668	child_cb (EV_P_ struct ev_child *w, int revents)
1564	{	1669	{
1565	ev_child_stop (EV_A_ w);	1670	ev_child_stop (EV_A_ w);
1566	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1671	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1567	}	1672	}
1568		1673
1569	pid_t pid = fork ();	1674	pid_t pid = fork ();
1570		1675
1571	if (pid < 0)	1676	if (pid < 0)
1572	// error	1677	// error
1573	else if (pid == 0)	1678	else if (pid == 0)
1574	{	1679	{
1575	// the forked child executes here	1680	// the forked child executes here
1576	exit (1);	1681	exit (1);
1577	}	1682	}
1578	else	1683	else
1579	{	1684	{
1580	ev_child_init (&cw, child_cb, pid, 0);	1685	ev_child_init (&cw, child_cb, pid, 0);
1581	ev_child_start (EV_DEFAULT_ &cw);	1686	ev_child_start (EV_DEFAULT_ &cw);
1582	}	1687	}
1583		1688
1584		1689
1585	=head2 C<ev_stat> - did the file attributes just change?	1690	=head2 C<ev_stat> - did the file attributes just change?
1586		1691
1587	This watches a filesystem path for attribute changes. That is, it calls	1692	This watches a file system path for attribute changes. That is, it calls
1588	C<stat> regularly (or when the OS says it changed) and sees if it changed	1693	C<stat> regularly (or when the OS says it changed) and sees if it changed
1589	compared to the last time, invoking the callback if it did.	1694	compared to the last time, invoking the callback if it did.
1590		1695
1591	The path does not need to exist: changing from "path exists" to "path does	1696	The path does not need to exist: changing from "path exists" to "path does
1592	not exist" is a status change like any other. The condition "path does	1697	not exist" is a status change like any other. The condition "path does
…		…
1610	as even with OS-supported change notifications, this can be	1715	as even with OS-supported change notifications, this can be
1611	resource-intensive.	1716	resource-intensive.
1612		1717
1613	At the time of this writing, only the Linux inotify interface is	1718	At the time of this writing, only the Linux inotify interface is
1614	implemented (implementing kqueue support is left as an exercise for the	1719	implemented (implementing kqueue support is left as an exercise for the
		1720	reader, note, however, that the author sees no way of implementing ev_stat
1615	reader). Inotify will be used to give hints only and should not change the	1721	semantics with kqueue). Inotify will be used to give hints only and should
1616	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1722	not change the semantics of C<ev_stat> watchers, which means that libev
1617	to fall back to regular polling again even with inotify, but changes are	1723	sometimes needs to fall back to regular polling again even with inotify,
1618	usually detected immediately, and if the file exists there will be no	1724	but changes are usually detected immediately, and if the file exists there
1619	polling.	1725	will be no polling.
1620		1726
1621	=head3 ABI Issues (Largefile Support)	1727	=head3 ABI Issues (Largefile Support)
1622		1728
1623	Libev by default (unless the user overrides this) uses the default	1729	Libev by default (unless the user overrides this) uses the default
1624	compilation environment, which means that on systems with optionally	1730	compilation environment, which means that on systems with large file
1625	disabled large file support, you get the 32 bit version of the stat	1731	support disabled by default, you get the 32 bit version of the stat
1626	structure. When using the library from programs that change the ABI to	1732	structure. When using the library from programs that change the ABI to
1627	use 64 bit file offsets the programs will fail. In that case you have to	1733	use 64 bit file offsets the programs will fail. In that case you have to
1628	compile libev with the same flags to get binary compatibility. This is	1734	compile libev with the same flags to get binary compatibility. This is
1629	obviously the case with any flags that change the ABI, but the problem is	1735	obviously the case with any flags that change the ABI, but the problem is
1630	most noticably with ev_stat and largefile support.	1736	most noticeably disabled with ev_stat and large file support.
		1737
		1738	The solution for this is to lobby your distribution maker to make large
		1739	file interfaces available by default (as e.g. FreeBSD does) and not
		1740	optional. Libev cannot simply switch on large file support because it has
		1741	to exchange stat structures with application programs compiled using the
		1742	default compilation environment.
1631		1743
1632	=head3 Inotify	1744	=head3 Inotify
1633		1745
1634	When C<inotify (7)> support has been compiled into libev (generally only	1746	When C<inotify (7)> support has been compiled into libev (generally only
1635	available on Linux) and present at runtime, it will be used to speed up	1747	available on Linux) and present at runtime, it will be used to speed up
…		…
1645	implement this functionality, due to the requirement of having a file	1757	implement this functionality, due to the requirement of having a file
1646	descriptor open on the object at all times).	1758	descriptor open on the object at all times).
1647		1759
1648	=head3 The special problem of stat time resolution	1760	=head3 The special problem of stat time resolution
1649		1761
1650	The C<stat ()> syscall only supports full-second resolution portably, and	1762	The C<stat ()> system call only supports full-second resolution portably, and
1651	even on systems where the resolution is higher, many filesystems still	1763	even on systems where the resolution is higher, many file systems still
1652	only support whole seconds.	1764	only support whole seconds.
1653		1765
1654	That means that, if the time is the only thing that changes, you might	1766	That means that, if the time is the only thing that changes, you can
1655	miss updates: on the first update, C<ev_stat> detects a change and calls	1767	easily miss updates: on the first update, C<ev_stat> detects a change and
1656	your callback, which does something. When there is another update within	1768	calls your callback, which does something. When there is another update
1657	the same second, C<ev_stat> will be unable to detect it.	1769	within the same second, C<ev_stat> will be unable to detect it as the stat
		1770	data does not change.
1658		1771
1659	The solution to this is to delay acting on a change for a second (or till	1772	The solution to this is to delay acting on a change for slightly more
1660	the next second boundary), using a roughly one-second delay C<ev_timer>	1773	than a second (or till slightly after the next full second boundary), using
1661	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>	1774	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);
1662	is added to work around small timing inconsistencies of some operating	1775	ev_timer_again (loop, w)>).
1663	systems.	1776
		1777	The C<.02> offset is added to work around small timing inconsistencies
		1778	of some operating systems (where the second counter of the current time
		1779	might be be delayed. One such system is the Linux kernel, where a call to
		1780	C<gettimeofday> might return a timestamp with a full second later than
		1781	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1782	update file times then there will be a small window where the kernel uses
		1783	the previous second to update file times but libev might already execute
		1784	the timer callback).
1664		1785
1665	=head3 Watcher-Specific Functions and Data Members	1786	=head3 Watcher-Specific Functions and Data Members
1666		1787
1667	=over 4	1788	=over 4
1668		1789
…		…
1674	C<path>. The C<interval> is a hint on how quickly a change is expected to	1795	C<path>. The C<interval> is a hint on how quickly a change is expected to
1675	be detected and should normally be specified as C<0> to let libev choose	1796	be detected and should normally be specified as C<0> to let libev choose
1676	a suitable value. The memory pointed to by C<path> must point to the same	1797	a suitable value. The memory pointed to by C<path> must point to the same
1677	path for as long as the watcher is active.	1798	path for as long as the watcher is active.
1678		1799
1679	The callback will be receive C<EV_STAT> when a change was detected,	1800	The callback will receive C<EV_STAT> when a change was detected, relative
1680	relative to the attributes at the time the watcher was started (or the	1801	to the attributes at the time the watcher was started (or the last change
1681	last change was detected).	1802	was detected).
1682		1803
1683	=item ev_stat_stat (loop, ev_stat *)	1804	=item ev_stat_stat (loop, ev_stat *)
1684		1805
1685	Updates the stat buffer immediately with new values. If you change the	1806	Updates the stat buffer immediately with new values. If you change the
1686	watched path in your callback, you could call this fucntion to avoid	1807	watched path in your callback, you could call this function to avoid
1687	detecting this change (while introducing a race condition). Can also be	1808	detecting this change (while introducing a race condition if you are not
1688	useful simply to find out the new values.	1809	the only one changing the path). Can also be useful simply to find out the
		1810	new values.
1689		1811
1690	=item ev_statdata attr [read-only]	1812	=item ev_statdata attr [read-only]
1691		1813
1692	The most-recently detected attributes of the file. Although the type is of	1814	The most-recently detected attributes of the file. Although the type is
1693	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types	1815	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
1694	suitable for your system. If the C<st_nlink> member is C<0>, then there	1816	suitable for your system, but you can only rely on the POSIX-standardised
		1817	members to be present. If the C<st_nlink> member is C<0>, then there was
1695	was some error while C<stat>ing the file.	1818	some error while C<stat>ing the file.
1696		1819
1697	=item ev_statdata prev [read-only]	1820	=item ev_statdata prev [read-only]
1698		1821
1699	The previous attributes of the file. The callback gets invoked whenever	1822	The previous attributes of the file. The callback gets invoked whenever
1700	C<prev> != C<attr>.	1823	C<prev> != C<attr>, or, more precisely, one or more of these members
		1824	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1825	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1701		1826
1702	=item ev_tstamp interval [read-only]	1827	=item ev_tstamp interval [read-only]
1703		1828
1704	The specified interval.	1829	The specified interval.
1705		1830
1706	=item const char *path [read-only]	1831	=item const char *path [read-only]
1707		1832
1708	The filesystem path that is being watched.	1833	The file system path that is being watched.
1709		1834
1710	=back	1835	=back
1711		1836
1712	=head3 Examples	1837	=head3 Examples
1713		1838
1714	Example: Watch C</etc/passwd> for attribute changes.	1839	Example: Watch C</etc/passwd> for attribute changes.
1715		1840
1716	static void	1841	static void
1717	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1842	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1718	{	1843	{
1719	/* /etc/passwd changed in some way */	1844	/* /etc/passwd changed in some way */
1720	if (w->attr.st_nlink)	1845	if (w->attr.st_nlink)
1721	{	1846	{
1722	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1847	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1723	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1848	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1724	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1849	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1725	}	1850	}
1726	else	1851	else
1727	/* you shalt not abuse printf for puts */	1852	/* you shalt not abuse printf for puts */
1728	puts ("wow, /etc/passwd is not there, expect problems. "	1853	puts ("wow, /etc/passwd is not there, expect problems. "
1729	"if this is windows, they already arrived\n");	1854	"if this is windows, they already arrived\n");
1730	}	1855	}
1731		1856
1732	...	1857	...
1733	ev_stat passwd;	1858	ev_stat passwd;
1734		1859
1735	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1860	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1736	ev_stat_start (loop, &passwd);	1861	ev_stat_start (loop, &passwd);
1737		1862
1738	Example: Like above, but additionally use a one-second delay so we do not	1863	Example: Like above, but additionally use a one-second delay so we do not
1739	miss updates (however, frequent updates will delay processing, too, so	1864	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	1865	one might do the work both on C<ev_stat> callback invocation I<and> on
1741	C<ev_timer> callback invocation).	1866	C<ev_timer> callback invocation).
1742		1867
1743	static ev_stat passwd;	1868	static ev_stat passwd;
1744	static ev_timer timer;	1869	static ev_timer timer;
1745		1870
1746	static void	1871	static void
1747	timer_cb (EV_P_ ev_timer *w, int revents)	1872	timer_cb (EV_P_ ev_timer *w, int revents)
1748	{	1873	{
1749	ev_timer_stop (EV_A_ w);	1874	ev_timer_stop (EV_A_ w);
1750		1875
1751	/* now it's one second after the most recent passwd change */	1876	/* now it's one second after the most recent passwd change */
1752	}	1877	}
1753		1878
1754	static void	1879	static void
1755	stat_cb (EV_P_ ev_stat *w, int revents)	1880	stat_cb (EV_P_ ev_stat *w, int revents)
1756	{	1881	{
1757	/* reset the one-second timer */	1882	/* reset the one-second timer */
1758	ev_timer_again (EV_A_ &timer);	1883	ev_timer_again (EV_A_ &timer);
1759	}	1884	}
1760		1885
1761	...	1886	...
1762	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1887	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1763	ev_stat_start (loop, &passwd);	1888	ev_stat_start (loop, &passwd);
1764	ev_timer_init (&timer, timer_cb, 0., 1.01);	1889	ev_timer_init (&timer, timer_cb, 0., 1.02);
1765		1890
1766		1891
1767	=head2 C<ev_idle> - when you've got nothing better to do...	1892	=head2 C<ev_idle> - when you've got nothing better to do...
1768		1893
1769	Idle watchers trigger events when no other events of the same or higher	1894	Idle watchers trigger events when no other events of the same or higher
…		…
1800	=head3 Examples	1925	=head3 Examples
1801		1926
1802	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1927	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1803	callback, free it. Also, use no error checking, as usual.	1928	callback, free it. Also, use no error checking, as usual.
1804		1929
1805	static void	1930	static void
1806	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1931	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1807	{	1932	{
1808	free (w);	1933	free (w);
1809	// now do something you wanted to do when the program has	1934	// now do something you wanted to do when the program has
1810	// no longer anything immediate to do.	1935	// no longer anything immediate to do.
1811	}	1936	}
1812		1937
1813	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1938	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1814	ev_idle_init (idle_watcher, idle_cb);	1939	ev_idle_init (idle_watcher, idle_cb);
1815	ev_idle_start (loop, idle_cb);	1940	ev_idle_start (loop, idle_cb);
1816		1941
1817		1942
1818	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1943	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1819		1944
1820	Prepare and check watchers are usually (but not always) used in tandem:	1945	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1839		1964
1840	This is done by examining in each prepare call which file descriptors need	1965	This is done by examining in each prepare call which file descriptors need
1841	to be watched by the other library, registering C<ev_io> watchers for	1966	to be watched by the other library, registering C<ev_io> watchers for
1842	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1967	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1843	provide just this functionality). Then, in the check watcher you check for	1968	provide just this functionality). Then, in the check watcher you check for
1844	any events that occured (by checking the pending status of all watchers	1969	any events that occurred (by checking the pending status of all watchers
1845	and stopping them) and call back into the library. The I/O and timer	1970	and stopping them) and call back into the library. The I/O and timer
1846	callbacks will never actually be called (but must be valid nevertheless,	1971	callbacks will never actually be called (but must be valid nevertheless,
1847	because you never know, you know?).	1972	because you never know, you know?).
1848		1973
1849	As another example, the Perl Coro module uses these hooks to integrate	1974	As another example, the Perl Coro module uses these hooks to integrate
…		…
1857		1982
1858	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1983	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
1859	priority, to ensure that they are being run before any other watchers	1984	priority, to ensure that they are being run before any other watchers
1860	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,	1985	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
1861	too) should not activate ("feed") events into libev. While libev fully	1986	too) should not activate ("feed") events into libev. While libev fully
1862	supports this, they will be called before other C<ev_check> watchers	1987	supports this, they might get executed before other C<ev_check> watchers
1863	did their job. As C<ev_check> watchers are often used to embed other	1988	did their job. As C<ev_check> watchers are often used to embed other
1864	(non-libev) event loops those other event loops might be in an unusable	1989	(non-libev) event loops those other event loops might be in an unusable
1865	state until their C<ev_check> watcher ran (always remind yourself to	1990	state until their C<ev_check> watcher ran (always remind yourself to
1866	coexist peacefully with others).	1991	coexist peacefully with others).
1867		1992
…		…
1882	=head3 Examples	2007	=head3 Examples
1883		2008
1884	There are a number of principal ways to embed other event loops or modules	2009	There are a number of principal ways to embed other event loops or modules
1885	into libev. Here are some ideas on how to include libadns into libev	2010	into libev. Here are some ideas on how to include libadns into libev
1886	(there is a Perl module named C<EV::ADNS> that does this, which you could	2011	(there is a Perl module named C<EV::ADNS> that does this, which you could
1887	use for an actually working example. Another Perl module named C<EV::Glib>	2012	use as a working example. Another Perl module named C<EV::Glib> embeds a
1888	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV	2013	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1889	into the Glib event loop).	2014	Glib event loop).
1890		2015
1891	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	2016	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1892	and in a check watcher, destroy them and call into libadns. What follows	2017	and in a check watcher, destroy them and call into libadns. What follows
1893	is pseudo-code only of course. This requires you to either use a low	2018	is pseudo-code only of course. This requires you to either use a low
1894	priority for the check watcher or use C<ev_clear_pending> explicitly, as	2019	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1895	the callbacks for the IO/timeout watchers might not have been called yet.	2020	the callbacks for the IO/timeout watchers might not have been called yet.
1896		2021
1897	static ev_io iow [nfd];	2022	static ev_io iow [nfd];
1898	static ev_timer tw;	2023	static ev_timer tw;
1899		2024
1900	static void	2025	static void
1901	io_cb (ev_loop *loop, ev_io *w, int revents)	2026	io_cb (ev_loop *loop, ev_io *w, int revents)
1902	{	2027	{
1903	}	2028	}
1904		2029
1905	// create io watchers for each fd and a timer before blocking	2030	// create io watchers for each fd and a timer before blocking
1906	static void	2031	static void
1907	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	2032	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1908	{	2033	{
1909	int timeout = 3600000;	2034	int timeout = 3600000;
1910	struct pollfd fds [nfd];	2035	struct pollfd fds [nfd];
1911	// actual code will need to loop here and realloc etc.	2036	// actual code will need to loop here and realloc etc.
1912	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	2037	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1913		2038
1914	/* the callback is illegal, but won't be called as we stop during check */	2039	/* the callback is illegal, but won't be called as we stop during check */
1915	ev_timer_init (&tw, 0, timeout * 1e-3);	2040	ev_timer_init (&tw, 0, timeout * 1e-3);
1916	ev_timer_start (loop, &tw);	2041	ev_timer_start (loop, &tw);
1917		2042
1918	// create one ev_io per pollfd	2043	// create one ev_io per pollfd
1919	for (int i = 0; i < nfd; ++i)	2044	for (int i = 0; i < nfd; ++i)
1920	{	2045	{
1921	ev_io_init (iow + i, io_cb, fds [i].fd,	2046	ev_io_init (iow + i, io_cb, fds [i].fd,
1922	((fds [i].events & POLLIN ? EV_READ : 0)	2047	((fds [i].events & POLLIN ? EV_READ : 0)
1923	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	2048	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1924		2049
1925	fds [i].revents = 0;	2050	fds [i].revents = 0;
1926	ev_io_start (loop, iow + i);	2051	ev_io_start (loop, iow + i);
1927	}	2052	}
1928	}	2053	}
1929		2054
1930	// stop all watchers after blocking	2055	// stop all watchers after blocking
1931	static void	2056	static void
1932	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	2057	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1933	{	2058	{
1934	ev_timer_stop (loop, &tw);	2059	ev_timer_stop (loop, &tw);
1935		2060
1936	for (int i = 0; i < nfd; ++i)	2061	for (int i = 0; i < nfd; ++i)
1937	{	2062	{
1938	// set the relevant poll flags	2063	// set the relevant poll flags
1939	// could also call adns_processreadable etc. here	2064	// could also call adns_processreadable etc. here
1940	struct pollfd *fd = fds + i;	2065	struct pollfd *fd = fds + i;
1941	int revents = ev_clear_pending (iow + i);	2066	int revents = ev_clear_pending (iow + i);
1942	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	2067	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1943	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	2068	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1944		2069
1945	// now stop the watcher	2070	// now stop the watcher
1946	ev_io_stop (loop, iow + i);	2071	ev_io_stop (loop, iow + i);
1947	}	2072	}
1948		2073
1949	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2074	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1950	}	2075	}
1951		2076
1952	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2077	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
1953	in the prepare watcher and would dispose of the check watcher.	2078	in the prepare watcher and would dispose of the check watcher.
1954		2079
1955	Method 3: If the module to be embedded supports explicit event	2080	Method 3: If the module to be embedded supports explicit event
1956	notification (adns does), you can also make use of the actual watcher	2081	notification (libadns does), you can also make use of the actual watcher
1957	callbacks, and only destroy/create the watchers in the prepare watcher.	2082	callbacks, and only destroy/create the watchers in the prepare watcher.
1958		2083
1959	static void	2084	static void
1960	timer_cb (EV_P_ ev_timer *w, int revents)	2085	timer_cb (EV_P_ ev_timer *w, int revents)
1961	{	2086	{
1962	adns_state ads = (adns_state)w->data;	2087	adns_state ads = (adns_state)w->data;
1963	update_now (EV_A);	2088	update_now (EV_A);
1964		2089
1965	adns_processtimeouts (ads, &tv_now);	2090	adns_processtimeouts (ads, &tv_now);
1966	}	2091	}
1967		2092
1968	static void	2093	static void
1969	io_cb (EV_P_ ev_io *w, int revents)	2094	io_cb (EV_P_ ev_io *w, int revents)
1970	{	2095	{
1971	adns_state ads = (adns_state)w->data;	2096	adns_state ads = (adns_state)w->data;
1972	update_now (EV_A);	2097	update_now (EV_A);
1973		2098
1974	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2099	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1975	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2100	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1976	}	2101	}
1977		2102
1978	// do not ever call adns_afterpoll	2103	// do not ever call adns_afterpoll
1979		2104
1980	Method 4: Do not use a prepare or check watcher because the module you	2105	Method 4: Do not use a prepare or check watcher because the module you
1981	want to embed is too inflexible to support it. Instead, youc na override	2106	want to embed is too inflexible to support it. Instead, you can override
1982	their poll function. The drawback with this solution is that the main	2107	their poll function. The drawback with this solution is that the main
1983	loop is now no longer controllable by EV. The C<Glib::EV> module does	2108	loop is now no longer controllable by EV. The C<Glib::EV> module does
1984	this.	2109	this.
1985		2110
1986	static gint	2111	static gint
1987	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2112	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1988	{	2113	{
1989	int got_events = 0;	2114	int got_events = 0;
1990		2115
1991	for (n = 0; n < nfds; ++n)	2116	for (n = 0; n < nfds; ++n)
1992	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2117	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1993		2118
1994	if (timeout >= 0)	2119	if (timeout >= 0)
1995	// create/start timer	2120	// create/start timer
1996		2121
1997	// poll	2122	// poll
1998	ev_loop (EV_A_ 0);	2123	ev_loop (EV_A_ 0);
1999		2124
2000	// stop timer again	2125	// stop timer again
2001	if (timeout >= 0)	2126	if (timeout >= 0)
2002	ev_timer_stop (EV_A_ &to);	2127	ev_timer_stop (EV_A_ &to);
2003		2128
2004	// stop io watchers again - their callbacks should have set	2129	// stop io watchers again - their callbacks should have set
2005	for (n = 0; n < nfds; ++n)	2130	for (n = 0; n < nfds; ++n)
2006	ev_io_stop (EV_A_ iow [n]);	2131	ev_io_stop (EV_A_ iow [n]);
2007		2132
2008	return got_events;	2133	return got_events;
2009	}	2134	}
2010		2135
2011		2136
2012	=head2 C<ev_embed> - when one backend isn't enough...	2137	=head2 C<ev_embed> - when one backend isn't enough...
2013		2138
2014	This is a rather advanced watcher type that lets you embed one event loop	2139	This is a rather advanced watcher type that lets you embed one event loop
…		…
2070		2195
2071	Configures the watcher to embed the given loop, which must be	2196	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	2197	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	2198	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,	2199	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).	2200	if you do not want that, you need to temporarily stop the embed watcher).
2076		2201
2077	=item ev_embed_sweep (loop, ev_embed *)	2202	=item ev_embed_sweep (loop, ev_embed *)
2078		2203
2079	Make a single, non-blocking sweep over the embedded loop. This works	2204	Make a single, non-blocking sweep over the embedded loop. This works
2080	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2205	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2081	apropriate way for embedded loops.	2206	appropriate way for embedded loops.
2082		2207
2083	=item struct ev_loop *other [read-only]	2208	=item struct ev_loop *other [read-only]
2084		2209
2085	The embedded event loop.	2210	The embedded event loop.
2086		2211
…		…
2088		2213
2089	=head3 Examples	2214	=head3 Examples
2090		2215
2091	Example: Try to get an embeddable event loop and embed it into the default	2216	Example: Try to get an embeddable event loop and embed it into the default
2092	event loop. If that is not possible, use the default loop. The default	2217	event loop. If that is not possible, use the default loop. The default
2093	loop is stored in C<loop_hi>, while the mebeddable loop is stored in	2218	loop is stored in C<loop_hi>, while the embeddable loop is stored in
2094	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be	2219	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2095	used).	2220	used).
2096		2221
2097	struct ev_loop *loop_hi = ev_default_init (0);	2222	struct ev_loop *loop_hi = ev_default_init (0);
2098	struct ev_loop *loop_lo = 0;	2223	struct ev_loop *loop_lo = 0;
2099	struct ev_embed embed;	2224	struct ev_embed embed;
2100		2225
2101	// see if there is a chance of getting one that works	2226	// see if there is a chance of getting one that works
2102	// (remember that a flags value of 0 means autodetection)	2227	// (remember that a flags value of 0 means autodetection)
2103	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2228	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2104	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2229	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2105	: 0;	2230	: 0;
2106		2231
2107	// if we got one, then embed it, otherwise default to loop_hi	2232	// if we got one, then embed it, otherwise default to loop_hi
2108	if (loop_lo)	2233	if (loop_lo)
2109	{	2234	{
2110	ev_embed_init (&embed, 0, loop_lo);	2235	ev_embed_init (&embed, 0, loop_lo);
2111	ev_embed_start (loop_hi, &embed);	2236	ev_embed_start (loop_hi, &embed);
2112	}	2237	}
2113	else	2238	else
2114	loop_lo = loop_hi;	2239	loop_lo = loop_hi;
2115		2240
2116	Example: Check if kqueue is available but not recommended and create	2241	Example: Check if kqueue is available but not recommended and create
2117	a kqueue backend for use with sockets (which usually work with any	2242	a kqueue backend for use with sockets (which usually work with any
2118	kqueue implementation). Store the kqueue/socket-only event loop in	2243	kqueue implementation). Store the kqueue/socket-only event loop in
2119	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2244	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2120		2245
2121	struct ev_loop *loop = ev_default_init (0);	2246	struct ev_loop *loop = ev_default_init (0);
2122	struct ev_loop *loop_socket = 0;	2247	struct ev_loop *loop_socket = 0;
2123	struct ev_embed embed;	2248	struct ev_embed embed;
2124		2249
2125	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2250	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2126	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2251	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2127	{	2252	{
2128	ev_embed_init (&embed, 0, loop_socket);	2253	ev_embed_init (&embed, 0, loop_socket);
2129	ev_embed_start (loop, &embed);	2254	ev_embed_start (loop, &embed);
2130	}	2255	}
2131		2256
2132	if (!loop_socket)	2257	if (!loop_socket)
2133	loop_socket = loop;	2258	loop_socket = loop;
2134		2259
2135	// now use loop_socket for all sockets, and loop for everything else	2260	// now use loop_socket for all sockets, and loop for everything else
2136		2261
2137		2262
2138	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2263	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2139		2264
2140	Fork watchers are called when a C<fork ()> was detected (usually because	2265	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2193		2318
2194	=item queueing from a signal handler context	2319	=item queueing from a signal handler context
2195		2320
2196	To implement race-free queueing, you simply add to the queue in the signal	2321	To implement race-free queueing, you simply add to the queue in the signal
2197	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2322	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2198	some fictitiuous SIGUSR1 handler:	2323	some fictitious SIGUSR1 handler:
2199		2324
2200	static ev_async mysig;	2325	static ev_async mysig;
2201		2326
2202	static void	2327	static void
2203	sigusr1_handler (void)	2328	sigusr1_handler (void)
…		…
2277	=item ev_async_send (loop, ev_async *)	2402	=item ev_async_send (loop, ev_async *)
2278		2403
2279	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2404	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2280	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2405	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2281	C<ev_feed_event>, this call is safe to do in other threads, signal or	2406	C<ev_feed_event>, this call is safe to do in other threads, signal or
2282	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding	2407	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2283	section below on what exactly this means).	2408	section below on what exactly this means).
2284		2409
2285	This call incurs the overhead of a syscall only once per loop iteration,	2410	This call incurs the overhead of a system call only once per loop iteration,
2286	so while the overhead might be noticable, it doesn't apply to repeated	2411	so while the overhead might be noticeable, it doesn't apply to repeated
2287	calls to C<ev_async_send>.	2412	calls to C<ev_async_send>.
2288		2413
2289	=item bool = ev_async_pending (ev_async *)	2414	=item bool = ev_async_pending (ev_async *)
2290		2415
2291	Returns a non-zero value when C<ev_async_send> has been called on the	2416	Returns a non-zero value when C<ev_async_send> has been called on the
…		…
2293	event loop.	2418	event loop.
2294		2419
2295	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When	2420	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,	2421	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	2422	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.	2423	quickly check whether invoking the loop might be a good idea.
2299		2424
2300	Not that this does I<not> check wether the watcher itself is pending, only	2425	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.	2426	whether it has been requested to make this watcher pending.
2302		2427
2303	=back	2428	=back
2304		2429
2305		2430
2306	=head1 OTHER FUNCTIONS	2431	=head1 OTHER FUNCTIONS
…		…
2317	or timeout without having to allocate/configure/start/stop/free one or	2442	or timeout without having to allocate/configure/start/stop/free one or
2318	more watchers yourself.	2443	more watchers yourself.
2319		2444
2320	If C<fd> is less than 0, then no I/O watcher will be started and events	2445	If C<fd> is less than 0, then no I/O watcher will be started and events
2321	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2446	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2322	C<events> set will be craeted and started.	2447	C<events> set will be created and started.
2323		2448
2324	If C<timeout> is less than 0, then no timeout watcher will be	2449	If C<timeout> is less than 0, then no timeout watcher will be
2325	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2450	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2326	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2451	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2327	dubious value.	2452	dubious value.
…		…
2329	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2454	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2330	passed an C<revents> set like normal event callbacks (a combination of	2455	passed an C<revents> set like normal event callbacks (a combination of
2331	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2456	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2332	value passed to C<ev_once>:	2457	value passed to C<ev_once>:
2333		2458
2334	static void stdin_ready (int revents, void *arg)	2459	static void stdin_ready (int revents, void *arg)
2335	{	2460	{
2336	if (revents & EV_TIMEOUT)	2461	if (revents & EV_TIMEOUT)
2337	/* doh, nothing entered */;	2462	/* doh, nothing entered */;
2338	else if (revents & EV_READ)	2463	else if (revents & EV_READ)
2339	/* stdin might have data for us, joy! */;	2464	/* stdin might have data for us, joy! */;
2340	}	2465	}
2341		2466
2342	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2467	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2343		2468
2344	=item ev_feed_event (ev_loop *, watcher *, int revents)	2469	=item ev_feed_event (ev_loop *, watcher *, int revents)
2345		2470
2346	Feeds the given event set into the event loop, as if the specified event	2471	Feeds the given event set into the event loop, as if the specified event
2347	had happened for the specified watcher (which must be a pointer to an	2472	had happened for the specified watcher (which must be a pointer to an
…		…
2352	Feed an event on the given fd, as if a file descriptor backend detected	2477	Feed an event on the given fd, as if a file descriptor backend detected
2353	the given events it.	2478	the given events it.
2354		2479
2355	=item ev_feed_signal_event (ev_loop *loop, int signum)	2480	=item ev_feed_signal_event (ev_loop *loop, int signum)
2356		2481
2357	Feed an event as if the given signal occured (C<loop> must be the default	2482	Feed an event as if the given signal occurred (C<loop> must be the default
2358	loop!).	2483	loop!).
2359		2484
2360	=back	2485	=back
2361		2486
2362		2487
…		…
2391	=back	2516	=back
2392		2517
2393	=head1 C++ SUPPORT	2518	=head1 C++ SUPPORT
2394		2519
2395	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2520	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2396	you to use some convinience methods to start/stop watchers and also change	2521	you to use some convenience methods to start/stop watchers and also change
2397	the callback model to a model using method callbacks on objects.	2522	the callback model to a model using method callbacks on objects.
2398		2523
2399	To use it,	2524	To use it,
2400		2525
2401	#include <ev++.h>	2526	#include <ev++.h>
2402		2527
2403	This automatically includes F<ev.h> and puts all of its definitions (many	2528	This automatically includes F<ev.h> and puts all of its definitions (many
2404	of them macros) into the global namespace. All C++ specific things are	2529	of them macros) into the global namespace. All C++ specific things are
2405	put into the C<ev> namespace. It should support all the same embedding	2530	put into the C<ev> namespace. It should support all the same embedding
2406	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2531	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2473	your compiler is good :), then the method will be fully inlined into the	2598	your compiler is good :), then the method will be fully inlined into the
2474	thunking function, making it as fast as a direct C callback.	2599	thunking function, making it as fast as a direct C callback.
2475		2600
2476	Example: simple class declaration and watcher initialisation	2601	Example: simple class declaration and watcher initialisation
2477		2602
2478	struct myclass	2603	struct myclass
2479	{	2604	{
2480	void io_cb (ev::io &w, int revents) { }	2605	void io_cb (ev::io &w, int revents) { }
2481	}	2606	}
2482		2607
2483	myclass obj;	2608	myclass obj;
2484	ev::io iow;	2609	ev::io iow;
2485	iow.set <myclass, &myclass::io_cb> (&obj);	2610	iow.set <myclass, &myclass::io_cb> (&obj);
2486		2611
2487	=item w->set<function> (void *data = 0)	2612	=item w->set<function> (void *data = 0)
2488		2613
2489	Also sets a callback, but uses a static method or plain function as	2614	Also sets a callback, but uses a static method or plain function as
2490	callback. The optional C<data> argument will be stored in the watcher's	2615	callback. The optional C<data> argument will be stored in the watcher's
…		…
2494		2619
2495	See the method-C<set> above for more details.	2620	See the method-C<set> above for more details.
2496		2621
2497	Example:	2622	Example:
2498		2623
2499	static void io_cb (ev::io &w, int revents) { }	2624	static void io_cb (ev::io &w, int revents) { }
2500	iow.set <io_cb> ();	2625	iow.set <io_cb> ();
2501		2626
2502	=item w->set (struct ev_loop *)	2627	=item w->set (struct ev_loop *)
2503		2628
2504	Associates a different C<struct ev_loop> with this watcher. You can only	2629	Associates a different C<struct ev_loop> with this watcher. You can only
2505	do this when the watcher is inactive (and not pending either).	2630	do this when the watcher is inactive (and not pending either).
2506		2631
2507	=item w->set ([args])	2632	=item w->set ([arguments])
2508		2633
2509	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2634	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2510	called at least once. Unlike the C counterpart, an active watcher gets	2635	called at least once. Unlike the C counterpart, an active watcher gets
2511	automatically stopped and restarted when reconfiguring it with this	2636	automatically stopped and restarted when reconfiguring it with this
2512	method.	2637	method.
2513		2638
2514	=item w->start ()	2639	=item w->start ()
…		…
2538	=back	2663	=back
2539		2664
2540	Example: Define a class with an IO and idle watcher, start one of them in	2665	Example: Define a class with an IO and idle watcher, start one of them in
2541	the constructor.	2666	the constructor.
2542		2667
2543	class myclass	2668	class myclass
2544	{	2669	{
2545	ev::io io; void io_cb (ev::io &w, int revents);	2670	ev::io io; void io_cb (ev::io &w, int revents);
2546	ev:idle idle void idle_cb (ev::idle &w, int revents);	2671	ev:idle idle void idle_cb (ev::idle &w, int revents);
2547		2672
2548	myclass (int fd)	2673	myclass (int fd)
2549	{	2674	{
2550	io .set <myclass, &myclass::io_cb > (this);	2675	io .set <myclass, &myclass::io_cb > (this);
2551	idle.set <myclass, &myclass::idle_cb> (this);	2676	idle.set <myclass, &myclass::idle_cb> (this);
2552		2677
2553	io.start (fd, ev::READ);	2678	io.start (fd, ev::READ);
2554	}	2679	}
2555	};	2680	};
2556		2681
2557		2682
2558	=head1 OTHER LANGUAGE BINDINGS	2683	=head1 OTHER LANGUAGE BINDINGS
2559		2684
2560	Libev does not offer other language bindings itself, but bindings for a	2685	Libev does not offer other language bindings itself, but bindings for a
2561	numbe rof languages exist in the form of third-party packages. If you know	2686	number of languages exist in the form of third-party packages. If you know
2562	any interesting language binding in addition to the ones listed here, drop	2687	any interesting language binding in addition to the ones listed here, drop
2563	me a note.	2688	me a note.
2564		2689
2565	=over 4	2690	=over 4
2566		2691
…		…
2570	libev. EV is developed together with libev. Apart from the EV core module,	2695	libev. EV is developed together with libev. Apart from the EV core module,
2571	there are additional modules that implement libev-compatible interfaces	2696	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	2697	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>).	2698	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2574		2699
2575	It can be found and installed via CPAN, its homepage is found at	2700	It can be found and installed via CPAN, its homepage is at
2576	L<http://software.schmorp.de/pkg/EV>.	2701	L<http://software.schmorp.de/pkg/EV>.
2577		2702
		2703	=item Python
		2704
		2705	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2706	seems to be quite complete and well-documented. Note, however, that the
		2707	patch they require for libev is outright dangerous as it breaks the ABI
		2708	for everybody else, and therefore, should never be applied in an installed
		2709	libev (if python requires an incompatible ABI then it needs to embed
		2710	libev).
		2711
2578	=item Ruby	2712	=item Ruby
2579		2713
2580	Tony Arcieri has written a ruby extension that offers access to a subset	2714	Tony Arcieri has written a ruby extension that offers access to a subset
2581	of the libev API and adds filehandle abstractions, asynchronous DNS and	2715	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	2716	more on top of it. It can be found via gem servers. Its homepage is at
2583	L<http://rev.rubyforge.org/>.	2717	L<http://rev.rubyforge.org/>.
2584		2718
2585	=item D	2719	=item D
2586		2720
2587	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	2721	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
2588	be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.	2722	be found at L<http://proj.llucax.com.ar/wiki/evd>.
2589		2723
2590	=back	2724	=back
2591		2725
2592		2726
2593	=head1 MACRO MAGIC	2727	=head1 MACRO MAGIC
2594		2728
2595	Libev can be compiled with a variety of options, the most fundamantal	2729	Libev can be compiled with a variety of options, the most fundamental
2596	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2730	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2597	functions and callbacks have an initial C<struct ev_loop *> argument.	2731	functions and callbacks have an initial C<struct ev_loop *> argument.
2598		2732
2599	To make it easier to write programs that cope with either variant, the	2733	To make it easier to write programs that cope with either variant, the
2600	following macros are defined:	2734	following macros are defined:
…		…
2605		2739
2606	This provides the loop I<argument> for functions, if one is required ("ev	2740	This provides the loop I<argument> for functions, if one is required ("ev
2607	loop argument"). The C<EV_A> form is used when this is the sole argument,	2741	loop argument"). The C<EV_A> form is used when this is the sole argument,
2608	C<EV_A_> is used when other arguments are following. Example:	2742	C<EV_A_> is used when other arguments are following. Example:
2609		2743
2610	ev_unref (EV_A);	2744	ev_unref (EV_A);
2611	ev_timer_add (EV_A_ watcher);	2745	ev_timer_add (EV_A_ watcher);
2612	ev_loop (EV_A_ 0);	2746	ev_loop (EV_A_ 0);
2613		2747
2614	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2748	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2615	which is often provided by the following macro.	2749	which is often provided by the following macro.
2616		2750
2617	=item C<EV_P>, C<EV_P_>	2751	=item C<EV_P>, C<EV_P_>
2618		2752
2619	This provides the loop I<parameter> for functions, if one is required ("ev	2753	This provides the loop I<parameter> for functions, if one is required ("ev
2620	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2754	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2621	C<EV_P_> is used when other parameters are following. Example:	2755	C<EV_P_> is used when other parameters are following. Example:
2622		2756
2623	// this is how ev_unref is being declared	2757	// this is how ev_unref is being declared
2624	static void ev_unref (EV_P);	2758	static void ev_unref (EV_P);
2625		2759
2626	// this is how you can declare your typical callback	2760	// this is how you can declare your typical callback
2627	static void cb (EV_P_ ev_timer *w, int revents)	2761	static void cb (EV_P_ ev_timer *w, int revents)
2628		2762
2629	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2763	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2630	suitable for use with C<EV_A>.	2764	suitable for use with C<EV_A>.
2631		2765
2632	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2766	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
…		…
2648		2782
2649	Example: Declare and initialise a check watcher, utilising the above	2783	Example: Declare and initialise a check watcher, utilising the above
2650	macros so it will work regardless of whether multiple loops are supported	2784	macros so it will work regardless of whether multiple loops are supported
2651	or not.	2785	or not.
2652		2786
2653	static void	2787	static void
2654	check_cb (EV_P_ ev_timer *w, int revents)	2788	check_cb (EV_P_ ev_timer *w, int revents)
2655	{	2789	{
2656	ev_check_stop (EV_A_ w);	2790	ev_check_stop (EV_A_ w);
2657	}	2791	}
2658		2792
2659	ev_check check;	2793	ev_check check;
2660	ev_check_init (&check, check_cb);	2794	ev_check_init (&check, check_cb);
2661	ev_check_start (EV_DEFAULT_ &check);	2795	ev_check_start (EV_DEFAULT_ &check);
2662	ev_loop (EV_DEFAULT_ 0);	2796	ev_loop (EV_DEFAULT_ 0);
2663		2797
2664	=head1 EMBEDDING	2798	=head1 EMBEDDING
2665		2799
2666	Libev can (and often is) directly embedded into host	2800	Libev can (and often is) directly embedded into host
2667	applications. Examples of applications that embed it include the Deliantra	2801	applications. Examples of applications that embed it include the Deliantra
…		…
2674	libev somewhere in your source tree).	2808	libev somewhere in your source tree).
2675		2809
2676	=head2 FILESETS	2810	=head2 FILESETS
2677		2811
2678	Depending on what features you need you need to include one or more sets of files	2812	Depending on what features you need you need to include one or more sets of files
2679	in your app.	2813	in your application.
2680		2814
2681	=head3 CORE EVENT LOOP	2815	=head3 CORE EVENT LOOP
2682		2816
2683	To include only the libev core (all the C<ev_*> functions), with manual	2817	To include only the libev core (all the C<ev_*> functions), with manual
2684	configuration (no autoconf):	2818	configuration (no autoconf):
2685		2819
2686	#define EV_STANDALONE 1	2820	#define EV_STANDALONE 1
2687	#include "ev.c"	2821	#include "ev.c"
2688		2822
2689	This will automatically include F<ev.h>, too, and should be done in a	2823	This will automatically include F<ev.h>, too, and should be done in a
2690	single C source file only to provide the function implementations. To use	2824	single C source file only to provide the function implementations. To use
2691	it, do the same for F<ev.h> in all files wishing to use this API (best	2825	it, do the same for F<ev.h> in all files wishing to use this API (best
2692	done by writing a wrapper around F<ev.h> that you can include instead and	2826	done by writing a wrapper around F<ev.h> that you can include instead and
2693	where you can put other configuration options):	2827	where you can put other configuration options):
2694		2828
2695	#define EV_STANDALONE 1	2829	#define EV_STANDALONE 1
2696	#include "ev.h"	2830	#include "ev.h"
2697		2831
2698	Both header files and implementation files can be compiled with a C++	2832	Both header files and implementation files can be compiled with a C++
2699	compiler (at least, thats a stated goal, and breakage will be treated	2833	compiler (at least, thats a stated goal, and breakage will be treated
2700	as a bug).	2834	as a bug).
2701		2835
2702	You need the following files in your source tree, or in a directory	2836	You need the following files in your source tree, or in a directory
2703	in your include path (e.g. in libev/ when using -Ilibev):	2837	in your include path (e.g. in libev/ when using -Ilibev):
2704		2838
2705	ev.h	2839	ev.h
2706	ev.c	2840	ev.c
2707	ev_vars.h	2841	ev_vars.h
2708	ev_wrap.h	2842	ev_wrap.h
2709		2843
2710	ev_win32.c required on win32 platforms only	2844	ev_win32.c required on win32 platforms only
2711		2845
2712	ev_select.c only when select backend is enabled (which is enabled by default)	2846	ev_select.c only when select backend is enabled (which is enabled by default)
2713	ev_poll.c only when poll backend is enabled (disabled by default)	2847	ev_poll.c only when poll backend is enabled (disabled by default)
2714	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2848	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2715	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2849	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2716	ev_port.c only when the solaris port backend is enabled (disabled by default)	2850	ev_port.c only when the solaris port backend is enabled (disabled by default)
2717		2851
2718	F<ev.c> includes the backend files directly when enabled, so you only need	2852	F<ev.c> includes the backend files directly when enabled, so you only need
2719	to compile this single file.	2853	to compile this single file.
2720		2854
2721	=head3 LIBEVENT COMPATIBILITY API	2855	=head3 LIBEVENT COMPATIBILITY API
2722		2856
2723	To include the libevent compatibility API, also include:	2857	To include the libevent compatibility API, also include:
2724		2858
2725	#include "event.c"	2859	#include "event.c"
2726		2860
2727	in the file including F<ev.c>, and:	2861	in the file including F<ev.c>, and:
2728		2862
2729	#include "event.h"	2863	#include "event.h"
2730		2864
2731	in the files that want to use the libevent API. This also includes F<ev.h>.	2865	in the files that want to use the libevent API. This also includes F<ev.h>.
2732		2866
2733	You need the following additional files for this:	2867	You need the following additional files for this:
2734		2868
2735	event.h	2869	event.h
2736	event.c	2870	event.c
2737		2871
2738	=head3 AUTOCONF SUPPORT	2872	=head3 AUTOCONF SUPPORT
2739		2873
2740	Instead of using C<EV_STANDALONE=1> and providing your config in	2874	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2741	whatever way you want, you can also C<m4_include([libev.m4])> in your	2875	whatever way you want, you can also C<m4_include([libev.m4])> in your
2742	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2876	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2743	include F<config.h> and configure itself accordingly.	2877	include F<config.h> and configure itself accordingly.
2744		2878
2745	For this of course you need the m4 file:	2879	For this of course you need the m4 file:
2746		2880
2747	libev.m4	2881	libev.m4
2748		2882
2749	=head2 PREPROCESSOR SYMBOLS/MACROS	2883	=head2 PREPROCESSOR SYMBOLS/MACROS
2750		2884
2751	Libev can be configured via a variety of preprocessor symbols you have to	2885	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	2886	define before including any of its files. The default in the absence of
2753	autoconf is noted for every option.	2887	autoconf is noted for every option.
2754		2888
2755	=over 4	2889	=over 4
2756		2890
2757	=item EV_STANDALONE	2891	=item EV_STANDALONE
…		…
2763	F<event.h> that are not directly supported by the libev core alone.	2897	F<event.h> that are not directly supported by the libev core alone.
2764		2898
2765	=item EV_USE_MONOTONIC	2899	=item EV_USE_MONOTONIC
2766		2900
2767	If defined to be C<1>, libev will try to detect the availability of the	2901	If defined to be C<1>, libev will try to detect the availability of the
2768	monotonic clock option at both compiletime and runtime. Otherwise no use	2902	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	2903	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	2904	usually have to link against librt or something similar. Enabling it when
2771	the functionality isn't available is safe, though, although you have	2905	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>	2906	to make sure you link against any libraries where the C<clock_gettime>
2773	function is hiding in (often F<-lrt>).	2907	function is hiding in (often F<-lrt>).
2774		2908
2775	=item EV_USE_REALTIME	2909	=item EV_USE_REALTIME
2776		2910
2777	If defined to be C<1>, libev will try to detect the availability of the	2911	If defined to be C<1>, libev will try to detect the availability of the
2778	realtime clock option at compiletime (and assume its availability at	2912	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	2913	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	2914	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2781	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2915	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2782	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2916	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2783		2917
2784	=item EV_USE_NANOSLEEP	2918	=item EV_USE_NANOSLEEP
…		…
2795	2.7 or newer, otherwise disabled.	2929	2.7 or newer, otherwise disabled.
2796		2930
2797	=item EV_USE_SELECT	2931	=item EV_USE_SELECT
2798		2932
2799	If undefined or defined to be C<1>, libev will compile in support for the	2933	If undefined or defined to be C<1>, libev will compile in support for the
2800	C<select>(2) backend. No attempt at autodetection will be done: if no	2934	C<select>(2) backend. No attempt at auto-detection will be done: if no
2801	other method takes over, select will be it. Otherwise the select backend	2935	other method takes over, select will be it. Otherwise the select backend
2802	will not be compiled in.	2936	will not be compiled in.
2803		2937
2804	=item EV_SELECT_USE_FD_SET	2938	=item EV_SELECT_USE_FD_SET
2805		2939
2806	If defined to C<1>, then the select backend will use the system C<fd_set>	2940	If defined to C<1>, then the select backend will use the system C<fd_set>
2807	structure. This is useful if libev doesn't compile due to a missing	2941	structure. This is useful if libev doesn't compile due to a missing
2808	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	2942	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
2809	exotic systems. This usually limits the range of file descriptors to some	2943	exotic systems. This usually limits the range of file descriptors to some
2810	low limit such as 1024 or might have other limitations (winsocket only	2944	low limit such as 1024 or might have other limitations (winsocket only
2811	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	2945	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2812	influence the size of the C<fd_set> used.	2946	influence the size of the C<fd_set> used.
2813		2947
…		…
2862	otherwise another method will be used as fallback. This is the preferred	2996	otherwise another method will be used as fallback. This is the preferred
2863	backend for Solaris 10 systems.	2997	backend for Solaris 10 systems.
2864		2998
2865	=item EV_USE_DEVPOLL	2999	=item EV_USE_DEVPOLL
2866		3000
2867	reserved for future expansion, works like the USE symbols above.	3001	Reserved for future expansion, works like the USE symbols above.
2868		3002
2869	=item EV_USE_INOTIFY	3003	=item EV_USE_INOTIFY
2870		3004
2871	If defined to be C<1>, libev will compile in support for the Linux inotify	3005	If defined to be C<1>, libev will compile in support for the Linux inotify
2872	interface to speed up C<ev_stat> watchers. Its actual availability will	3006	interface to speed up C<ev_stat> watchers. Its actual availability will
…		…
2879	access is atomic with respect to other threads or signal contexts. No such	3013	access is atomic with respect to other threads or signal contexts. No such
2880	type is easily found in the C language, so you can provide your own type	3014	type is easily found in the C language, so you can provide your own type
2881	that you know is safe for your purposes. It is used both for signal handler "locking"	3015	that you know is safe for your purposes. It is used both for signal handler "locking"
2882	as well as for signal and thread safety in C<ev_async> watchers.	3016	as well as for signal and thread safety in C<ev_async> watchers.
2883		3017
2884	In the absense of this define, libev will use C<sig_atomic_t volatile>	3018	In the absence of this define, libev will use C<sig_atomic_t volatile>
2885	(from F<signal.h>), which is usually good enough on most platforms.	3019	(from F<signal.h>), which is usually good enough on most platforms.
2886		3020
2887	=item EV_H	3021	=item EV_H
2888		3022
2889	The name of the F<ev.h> header file used to include it. The default if	3023	The name of the F<ev.h> header file used to include it. The default if
…		…
2928	When doing priority-based operations, libev usually has to linearly search	3062	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	3063	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	3064	and time, so using the defaults of five priorities (-2 .. +2) is usually
2931	fine.	3065	fine.
2932		3066
2933	If your embedding app does not need any priorities, defining these both to	3067	If your embedding application does not need any priorities, defining these both to
2934	C<0> will save some memory and cpu.	3068	C<0> will save some memory and CPU.
2935		3069
2936	=item EV_PERIODIC_ENABLE	3070	=item EV_PERIODIC_ENABLE
2937		3071
2938	If undefined or defined to be C<1>, then periodic timers are supported. If	3072	If undefined or defined to be C<1>, then periodic timers are supported. If
2939	defined to be C<0>, then they are not. Disabling them saves a few kB of	3073	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
2966	defined to be C<0>, then they are not.	3100	defined to be C<0>, then they are not.
2967		3101
2968	=item EV_MINIMAL	3102	=item EV_MINIMAL
2969		3103
2970	If you need to shave off some kilobytes of code at the expense of some	3104	If you need to shave off some kilobytes of code at the expense of some
2971	speed, define this symbol to C<1>. Currently only used for gcc to override	3105	speed, define this symbol to C<1>. Currently this is used to override some
2972	some inlining decisions, saves roughly 30% codesize of amd64.	3106	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3107	much smaller 2-heap for timer management over the default 4-heap.
2973		3108
2974	=item EV_PID_HASHSIZE	3109	=item EV_PID_HASHSIZE
2975		3110
2976	C<ev_child> watchers use a small hash table to distribute workload by	3111	C<ev_child> watchers use a small hash table to distribute workload by
2977	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3112	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
…		…
2984	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	3119	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2985	usually more than enough. If you need to manage thousands of C<ev_stat>	3120	usually more than enough. If you need to manage thousands of C<ev_stat>
2986	watchers you might want to increase this value (I<must> be a power of	3121	watchers you might want to increase this value (I<must> be a power of
2987	two).	3122	two).
2988		3123
		3124	=item EV_USE_4HEAP
		3125
		3126	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3127	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3128	to C<1>. The 4-heap uses more complicated (longer) code but has
		3129	noticeably faster performance with many (thousands) of watchers.
		3130
		3131	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3132	(disabled).
		3133
		3134	=item EV_HEAP_CACHE_AT
		3135
		3136	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3137	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3138	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3139	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3140	but avoids random read accesses on heap changes. This improves performance
		3141	noticeably with with many (hundreds) of watchers.
		3142
		3143	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3144	(disabled).
		3145
		3146	=item EV_VERIFY
		3147
		3148	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3149	be done: If set to C<0>, no internal verification code will be compiled
		3150	in. If set to C<1>, then verification code will be compiled in, but not
		3151	called. If set to C<2>, then the internal verification code will be
		3152	called once per loop, which can slow down libev. If set to C<3>, then the
		3153	verification code will be called very frequently, which will slow down
		3154	libev considerably.
		3155
		3156	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3157	C<0.>
		3158
2989	=item EV_COMMON	3159	=item EV_COMMON
2990		3160
2991	By default, all watchers have a C<void *data> member. By redefining	3161	By default, all watchers have a C<void *data> member. By redefining
2992	this macro to a something else you can include more and other types of	3162	this macro to a something else you can include more and other types of
2993	members. You have to define it each time you include one of the files,	3163	members. You have to define it each time you include one of the files,
2994	though, and it must be identical each time.	3164	though, and it must be identical each time.
2995		3165
2996	For example, the perl EV module uses something like this:	3166	For example, the perl EV module uses something like this:
2997		3167
2998	#define EV_COMMON \	3168	#define EV_COMMON \
2999	SV *self; /* contains this struct */ \	3169	SV *self; /* contains this struct */ \
3000	SV *cb_sv, *fh /* note no trailing ";" */	3170	SV *cb_sv, *fh /* note no trailing ";" */
3001		3171
3002	=item EV_CB_DECLARE (type)	3172	=item EV_CB_DECLARE (type)
3003		3173
3004	=item EV_CB_INVOKE (watcher, revents)	3174	=item EV_CB_INVOKE (watcher, revents)
3005		3175
…		…
3012	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3182	avoid the C<struct ev_loop *> as first argument in all cases, or to use
3013	method calls instead of plain function calls in C++.	3183	method calls instead of plain function calls in C++.
3014		3184
3015	=head2 EXPORTED API SYMBOLS	3185	=head2 EXPORTED API SYMBOLS
3016		3186
3017	If you need to re-export the API (e.g. via a dll) and you need a list of	3187	If you need to re-export the API (e.g. via a DLL) and you need a list of
3018	exported symbols, you can use the provided F<Symbol.*> files which list	3188	exported symbols, you can use the provided F<Symbol.*> files which list
3019	all public symbols, one per line:	3189	all public symbols, one per line:
3020		3190
3021	Symbols.ev for libev proper	3191	Symbols.ev for libev proper
3022	Symbols.event for the libevent emulation	3192	Symbols.event for the libevent emulation
3023		3193
3024	This can also be used to rename all public symbols to avoid clashes with	3194	This can also be used to rename all public symbols to avoid clashes with
3025	multiple versions of libev linked together (which is obviously bad in	3195	multiple versions of libev linked together (which is obviously bad in
3026	itself, but sometimes it is inconvinient to avoid this).	3196	itself, but sometimes it is inconvenient to avoid this).
3027		3197
3028	A sed command like this will create wrapper C<#define>'s that you need to	3198	A sed command like this will create wrapper C<#define>'s that you need to
3029	include before including F<ev.h>:	3199	include before including F<ev.h>:
3030		3200
3031	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3201	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3048	file.	3218	file.
3049		3219
3050	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3220	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3051	that everybody includes and which overrides some configure choices:	3221	that everybody includes and which overrides some configure choices:
3052		3222
3053	#define EV_MINIMAL 1	3223	#define EV_MINIMAL 1
3054	#define EV_USE_POLL 0	3224	#define EV_USE_POLL 0
3055	#define EV_MULTIPLICITY 0	3225	#define EV_MULTIPLICITY 0
3056	#define EV_PERIODIC_ENABLE 0	3226	#define EV_PERIODIC_ENABLE 0
3057	#define EV_STAT_ENABLE 0	3227	#define EV_STAT_ENABLE 0
3058	#define EV_FORK_ENABLE 0	3228	#define EV_FORK_ENABLE 0
3059	#define EV_CONFIG_H <config.h>	3229	#define EV_CONFIG_H <config.h>
3060	#define EV_MINPRI 0	3230	#define EV_MINPRI 0
3061	#define EV_MAXPRI 0	3231	#define EV_MAXPRI 0
3062		3232
3063	#include "ev++.h"	3233	#include "ev++.h"
3064		3234
3065	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3235	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3066		3236
3067	#include "ev_cpp.h"	3237	#include "ev_cpp.h"
3068	#include "ev.c"	3238	#include "ev.c"
3069		3239
3070		3240
3071	=head1 THREADS AND COROUTINES	3241	=head1 THREADS AND COROUTINES
3072		3242
3073	=head2 THREADS	3243	=head2 THREADS
3074		3244
3075	Libev itself is completely threadsafe, but it uses no locking. This	3245	Libev itself is thread-safe (unless the opposite is specifically
		3246	documented for a function), but it uses no locking itself. This means that
3076	means that you can use as many loops as you want in parallel, as long as	3247	you can use as many loops as you want in parallel, as long as only one
3077	only one thread ever calls into one libev function with the same loop	3248	thread ever calls into one libev function with the same loop parameter:
3078	parameter.	3249	libev guarentees that different event loops share no data structures that
		3250	need locking.
3079		3251
3080	Or put differently: calls with different loop parameters can be done in	3252	Or to put it differently: calls with different loop parameters can be done
3081	parallel from multiple threads, calls with the same loop parameter must be	3253	concurrently from multiple threads, calls with the same loop parameter
3082	done serially (but can be done from different threads, as long as only one	3254	must be done serially (but can be done from different threads, as long as
3083	thread ever is inside a call at any point in time, e.g. by using a mutex	3255	only one thread ever is inside a call at any point in time, e.g. by using
3084	per loop).	3256	a mutex per loop).
3085		3257
3086	If you want to know which design is best for your problem, then I cannot	3258	Specifically to support threads (and signal handlers), libev implements
3087	help you but by giving some generic advice:	3259	so-called C<ev_async> watchers, which allow some limited form of
		3260	concurrency on the same event loop.
		3261
		3262	If you want to know which design (one loop, locking, or multiple loops
		3263	without or something else still) is best for your problem, then I cannot
		3264	help you. I can give some generic advice however:
3088		3265
3089	=over 4	3266	=over 4
3090		3267
3091	=item * most applications have a main thread: use the default libev loop	3268	=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.	3269	in that thread, or create a separate thread running only the default loop.
3093		3270
3094	This helps integrating other libraries or software modules that use libev	3271	This helps integrating other libraries or software modules that use libev
3095	themselves and don't care/know about threading.	3272	themselves and don't care/know about threading.
3096		3273
3097	=item * one loop per thread is usually a good model.	3274	=item * one loop per thread is usually a good model.
3098		3275
3099	Doing this is almost never wrong, sometimes a better-performance model	3276	Doing this is almost never wrong, sometimes a better-performance model
3100	exists, but it is always a good start.	3277	exists, but it is always a good start.
3101		3278
3102	=item * other models exist, such as the leader/follower pattern, where one	3279	=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.	3280	loop is handed through multiple threads in a kind of round-robin fashion.
3104		3281
3105	Chosing a model is hard - look around, learn, know that usually you cna do	3282	Choosing a model is hard - look around, learn, know that usually you can do
3106	better than you currently do :-)	3283	better than you currently do :-)
3107		3284
3108	=item * often you need to talk to some other thread which blocks in the	3285	=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	3286	event loop - C<ev_async> watchers can be used to wake them up from other
3110	threads safely (or from signal contexts...).	3287	threads safely (or from signal contexts...).
3111		3288
		3289	=item * some watcher types are only supported in the default loop - use
		3290	C<ev_async> watchers to tell your other loops about any such events.
		3291
3112	=back	3292	=back
3113		3293
3114	=head2 COROUTINES	3294	=head2 COROUTINES
3115		3295
3116	Libev is much more accomodating to coroutines ("cooperative threads"):	3296	Libev is much more accommodating to coroutines ("cooperative threads"):
3117	libev fully supports nesting calls to it's functions from different	3297	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	3298	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	3299	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	3300	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.	3301	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	3342	correct watcher to remove. The lists are usually short (you don't usually
3163	have many watchers waiting for the same fd or signal).	3343	have many watchers waiting for the same fd or signal).
3164		3344
3165	=item Finding the next timer in each loop iteration: O(1)	3345	=item Finding the next timer in each loop iteration: O(1)
3166		3346
3167	By virtue of using a binary heap, the next timer is always found at the	3347	By virtue of using a binary or 4-heap, the next timer is always found at a
3168	beginning of the storage array.	3348	fixed position in the storage array.
3169		3349
3170	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3350	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3171		3351
3172	A change means an I/O watcher gets started or stopped, which requires	3352	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	3353	libev to recalculate its status (and possibly tell the kernel, depending
3174	on backend and wether C<ev_io_set> was used).	3354	on backend and whether C<ev_io_set> was used).
3175		3355
3176	=item Activating one watcher (putting it into the pending state): O(1)	3356	=item Activating one watcher (putting it into the pending state): O(1)
3177		3357
3178	=item Priority handling: O(number_of_priorities)	3358	=item Priority handling: O(number_of_priorities)
3179		3359
…		…
3186		3366
3187	=item Processing ev_async_send: O(number_of_async_watchers)	3367	=item Processing ev_async_send: O(number_of_async_watchers)
3188		3368
3189	=item Processing signals: O(max_signal_number)	3369	=item Processing signals: O(max_signal_number)
3190		3370
3191	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3371	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	3372	calls in the current loop iteration. Checking for async and signal events
3193	involves iterating over all running async watchers or all signal numbers.	3373	involves iterating over all running async watchers or all signal numbers.
3194		3374
3195	=back	3375	=back
3196		3376
3197		3377
3198	=head1 Win32 platform limitations and workarounds	3378	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3199		3379
3200	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3380	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	3381	requires, and its I/O model is fundamentally incompatible with the POSIX
3202	model. Libev still offers limited functionality on this platform in	3382	model. Libev still offers limited functionality on this platform in
3203	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3383	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3204	descriptors. This only applies when using Win32 natively, not when using	3384	descriptors. This only applies when using Win32 natively, not when using
3205	e.g. cygwin.	3385	e.g. cygwin.
3206		3386
		3387	Lifting these limitations would basically require the full
		3388	re-implementation of the I/O system. If you are into these kinds of
		3389	things, then note that glib does exactly that for you in a very portable
		3390	way (note also that glib is the slowest event library known to man).
		3391
3207	There is no supported compilation method available on windows except	3392	There is no supported compilation method available on windows except
3208	embedding it into other applications.	3393	embedding it into other applications.
3209		3394
		3395	Not a libev limitation but worth mentioning: windows apparently doesn't
		3396	accept large writes: instead of resulting in a partial write, windows will
		3397	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3398	so make sure you only write small amounts into your sockets (less than a
		3399	megabyte seems safe, but thsi apparently depends on the amount of memory
		3400	available).
		3401
3210	Due to the many, low, and arbitrary limits on the win32 platform and the	3402	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	3403	the abysmal performance of winsockets, using a large number of sockets
3212	recommended (and not reasonable). If your program needs to use more than	3404	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	3405	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	3406	different implementation for windows, as libev offers the POSIX readiness
3215	be implemented efficiently on windows (microsoft monopoly games).	3407	notification model, which cannot be implemented efficiently on windows
		3408	(Microsoft monopoly games).
		3409
		3410	A typical way to use libev under windows is to embed it (see the embedding
		3411	section for details) and use the following F<evwrap.h> header file instead
		3412	of F<ev.h>:
		3413
		3414	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3415	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3416
		3417	#include "ev.h"
		3418
		3419	And compile the following F<evwrap.c> file into your project (make sure
		3420	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3421
		3422	#include "evwrap.h"
		3423	#include "ev.c"
3216		3424
3217	=over 4	3425	=over 4
3218		3426
3219	=item The winsocket select function	3427	=item The winsocket select function
3220		3428
3221	The winsocket C<select> function doesn't follow POSIX in that it requires	3429	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	3430	requires socket I<handles> and not socket I<file descriptors> (it is
3223	very inefficient, and also requires a mapping from file descriptors	3431	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>,	3432	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	3433	C runtime provides the function C<_open_osfhandle> for this). See the
3226	symbols for more info.	3434	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3435	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3227		3436
3228	The configuration for a "naked" win32 using the microsoft runtime	3437	The configuration for a "naked" win32 using the Microsoft runtime
3229	libraries and raw winsocket select is:	3438	libraries and raw winsocket select is:
3230		3439
3231	#define EV_USE_SELECT 1	3440	#define EV_USE_SELECT 1
3232	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3441	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3233		3442
3234	Note that winsockets handling of fd sets is O(n), so you can easily get a	3443	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.	3444	complexity in the O(n²) range when using win32.
3236		3445
3237	=item Limited number of file descriptors	3446	=item Limited number of file descriptors
3238		3447
3239	Windows has numerous arbitrary (and low) limits on things. Early versions	3448	Windows has numerous arbitrary (and low) limits on things.
3240	of winsocket's select only supported waiting for a max. of C<64> handles	3449
		3450	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	3451	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	3452	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).	3453	recommends spawning a chain of threads and wait for 63 handles and the
		3454	previous thread in each. Great).
3244		3455
3245	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3456	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	3457	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	3458	call (which might be in libev or elsewhere, for example, perl does its own
3248	select emulation on windows).	3459	select emulation on windows).
3249		3460
3250	Another limit is the number of file descriptors in the microsoft runtime	3461	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	3462	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	3463	or something like this inside Microsoft). You can increase this by calling
3253	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3464	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3254	arbitrary limit), but is broken in many versions of the microsoft runtime	3465	arbitrary limit), but is broken in many versions of the Microsoft runtime
3255	libraries.	3466	libraries.
3256		3467
3257	This might get you to about C<512> or C<2048> sockets (depending on	3468	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	3469	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	3470	wrap all I/O functions and provide your own fd management, but the cost of
…		…
3266		3477
3267	In addition to a working ISO-C implementation, libev relies on a few	3478	In addition to a working ISO-C implementation, libev relies on a few
3268	additional extensions:	3479	additional extensions:
3269		3480
3270	=over 4	3481	=over 4
		3482
		3483	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3484	calling conventions regardless of C<ev_watcher_type *>.
		3485
		3486	Libev assumes not only that all watcher pointers have the same internal
		3487	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3488	assumes that the same (machine) code can be used to call any watcher
		3489	callback: The watcher callbacks have different type signatures, but libev
		3490	calls them using an C<ev_watcher *> internally.
3271		3491
3272	=item C<sig_atomic_t volatile> must be thread-atomic as well	3492	=item C<sig_atomic_t volatile> must be thread-atomic as well
3273		3493
3274	The type C<sig_atomic_t volatile> (or whatever is defined as	3494	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	3495	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
…		…
3287		3507
3288	The most portable way to handle signals is to block signals in all threads	3508	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	3509	except the initial one, and run the default loop in the initial thread as
3290	well.	3510	well.
3291		3511
		3512	=item C<long> must be large enough for common memory allocation sizes
		3513
		3514	To improve portability and simplify using libev, libev uses C<long>
		3515	internally instead of C<size_t> when allocating its data structures. On
		3516	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3517	is still at least 31 bits everywhere, which is enough for hundreds of
		3518	millions of watchers.
		3519
		3520	=item C<double> must hold a time value in seconds with enough accuracy
		3521
		3522	The type C<double> is used to represent timestamps. It is required to
		3523	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3524	enough for at least into the year 4000. This requirement is fulfilled by
		3525	implementations implementing IEEE 754 (basically all existing ones).
		3526
3292	=back	3527	=back
3293		3528
3294	If you know of other additional requirements drop me a note.	3529	If you know of other additional requirements drop me a note.
3295		3530
3296		3531
		3532	=head1 COMPILER WARNINGS
		3533
		3534	Depending on your compiler and compiler settings, you might get no or a
		3535	lot of warnings when compiling libev code. Some people are apparently
		3536	scared by this.
		3537
		3538	However, these are unavoidable for many reasons. For one, each compiler
		3539	has different warnings, and each user has different tastes regarding
		3540	warning options. "Warn-free" code therefore cannot be a goal except when
		3541	targeting a specific compiler and compiler-version.
		3542
		3543	Another reason is that some compiler warnings require elaborate
		3544	workarounds, or other changes to the code that make it less clear and less
		3545	maintainable.
		3546
		3547	And of course, some compiler warnings are just plain stupid, or simply
		3548	wrong (because they don't actually warn about the condition their message
		3549	seems to warn about).
		3550
		3551	While libev is written to generate as few warnings as possible,
		3552	"warn-free" code is not a goal, and it is recommended not to build libev
		3553	with any compiler warnings enabled unless you are prepared to cope with
		3554	them (e.g. by ignoring them). Remember that warnings are just that:
		3555	warnings, not errors, or proof of bugs.
		3556
		3557
		3558	=head1 VALGRIND
		3559
		3560	Valgrind has a special section here because it is a popular tool that is
		3561	highly useful, but valgrind reports are very hard to interpret.
		3562
		3563	If you think you found a bug (memory leak, uninitialised data access etc.)
		3564	in libev, then check twice: If valgrind reports something like:
		3565
		3566	==2274== definitely lost: 0 bytes in 0 blocks.
		3567	==2274== possibly lost: 0 bytes in 0 blocks.
		3568	==2274== still reachable: 256 bytes in 1 blocks.
		3569
		3570	Then there is no memory leak. Similarly, under some circumstances,
		3571	valgrind might report kernel bugs as if it were a bug in libev, or it
		3572	might be confused (it is a very good tool, but only a tool).
		3573
		3574	If you are unsure about something, feel free to contact the mailing list
		3575	with the full valgrind report and an explanation on why you think this is
		3576	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3577	no bug" answer and take the chance of learning how to interpret valgrind
		3578	properly.
		3579
		3580	If you need, for some reason, empty reports from valgrind for your project
		3581	I suggest using suppression lists.
		3582
		3583
3297	=head1 AUTHOR	3584	=head1 AUTHOR
3298		3585
3299	Marc Lehmann <libev@schmorp.de>.	3586	Marc Lehmann <libev@schmorp.de>.
3300		3587

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