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Revision 1.159 by root, Thu May 22 02:44:57 2008 UTC vs.
Revision 1.168 by root, Mon Jun 9 14:31:36 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
…		…
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	readiness notifications you get per iteration.	362	readiness notifications you get per iteration.
342		363
…		…
354	For few fds, this backend is a bit little slower than poll and select,	375	For few fds, this backend is a bit little slower than poll and select,
355	but it scales phenomenally better. While poll and select usually scale	376	but it scales phenomenally better. While poll and select usually scale
356	like O(total_fds) where n is the total number of fds (or the highest fd),	377	like O(total_fds) where n is the total number of fds (or the highest fd),
357	epoll scales either O(1) or O(active_fds). The epoll design has a number	378	epoll scales either O(1) or O(active_fds). The epoll design has a number
358	of shortcomings, such as silently dropping events in some hard-to-detect	379	of shortcomings, such as silently dropping events in some hard-to-detect
359	cases and requiring a syscall per fd change, no fork support and bad	380	cases and requiring a system call per fd change, no fork support and bad
360	support for dup.	381	support for dup.
361		382
362	While stopping, setting and starting an I/O watcher in the same iteration	383	While stopping, setting and starting an I/O watcher in the same iteration
363	will result in some caching, there is still a syscall per such incident	384	will result in some caching, there is still a system call per such incident
364	(because the fd could point to a different file description now), so its	385	(because the fd could point to a different file description now), so its
365	best to avoid that. Also, C<dup ()>'ed file descriptors might not work	386	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
366	very well if you register events for both fds.	387	very well if you register events for both fds.
367		388
368	Please note that epoll sometimes generates spurious notifications, so you	389	Please note that epoll sometimes generates spurious notifications, so you
…		…
371		392
372	Best performance from this backend is achieved by not unregistering all	393	Best performance from this backend is achieved by not unregistering all
373	watchers for a file descriptor until it has been closed, if possible, i.e.	394	watchers for a file descriptor until it has been closed, if possible, i.e.
374	keep at least one watcher active per fd at all times.	395	keep at least one watcher active per fd at all times.
375		396
376	While nominally embeddeble in other event loops, this feature is broken in	397	While nominally embeddable in other event loops, this feature is broken in
377	all kernel versions tested so far.	398	all kernel versions tested so far.
378		399
379	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	400	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
380		401
381	Kqueue deserves special mention, as at the time of this writing, it	402	Kqueue deserves special mention, as at the time of this writing, it
382	was broken on all BSDs except NetBSD (usually it doesn't work reliably	403	was broken on all BSDs except NetBSD (usually it doesn't work reliably
383	with anything but sockets and pipes, except on Darwin, where of course	404	with anything but sockets and pipes, except on Darwin, where of course
384	it's completely useless). For this reason it's not being "autodetected"	405	it's completely useless). For this reason it's not being "auto-detected"
385	unless you explicitly specify it explicitly in the flags (i.e. using	406	unless you explicitly specify it explicitly in the flags (i.e. using
386	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)	407	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
387	system like NetBSD.	408	system like NetBSD.
388		409
389	You still can embed kqueue into a normal poll or select backend and use it	410	You still can embed kqueue into a normal poll or select backend and use it
…		…
391	the target platform). See C<ev_embed> watchers for more info.	412	the target platform). See C<ev_embed> watchers for more info.
392		413
393	It scales in the same way as the epoll backend, but the interface to the	414	It scales in the same way as the epoll backend, but the interface to the
394	kernel is more efficient (which says nothing about its actual speed, of	415	kernel is more efficient (which says nothing about its actual speed, of
395	course). While stopping, setting and starting an I/O watcher does never	416	course). While stopping, setting and starting an I/O watcher does never
396	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to	417	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
397	two event changes per incident, support for C<fork ()> is very bad and it	418	two event changes per incident, support for C<fork ()> is very bad and it
398	drops fds silently in similarly hard-to-detect cases.	419	drops fds silently in similarly hard-to-detect cases.
399		420
400	This backend usually performs well under most conditions.	421	This backend usually performs well under most conditions.
401		422
…		…
416	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	437	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
417		438
418	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	439	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
419	it's really slow, but it still scales very well (O(active_fds)).	440	it's really slow, but it still scales very well (O(active_fds)).
420		441
421	Please note that solaris event ports can deliver a lot of spurious	442	Please note that Solaris event ports can deliver a lot of spurious
422	notifications, so you need to use non-blocking I/O or other means to avoid	443	notifications, so you need to use non-blocking I/O or other means to avoid
423	blocking when no data (or space) is available.	444	blocking when no data (or space) is available.
424		445
425	While this backend scales well, it requires one system call per active	446	While this backend scales well, it requires one system call per active
426	file descriptor per loop iteration. For small and medium numbers of file	447	file descriptor per loop iteration. For small and medium numbers of file
…		…
439		460
440	It is definitely not recommended to use this flag.	461	It is definitely not recommended to use this flag.
441		462
442	=back	463	=back
443		464
444	If one or more of these are ored into the flags value, then only these	465	If one or more of these are or'ed into the flags value, then only these
445	backends will be tried (in the reverse order as listed here). If none are	466	backends will be tried (in the reverse order as listed here). If none are
446	specified, all backends in C<ev_recommended_backends ()> will be tried.	467	specified, all backends in C<ev_recommended_backends ()> will be tried.
447		468
448	The most typical usage is like this:	469	The most typical usage is like this:
449		470
450	if (!ev_default_loop (0))	471	if (!ev_default_loop (0))
451	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	472	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
452		473
453	Restrict libev to the select and poll backends, and do not allow	474	Restrict libev to the select and poll backends, and do not allow
454	environment settings to be taken into account:	475	environment settings to be taken into account:
455		476
456	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);	477	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
457		478
458	Use whatever libev has to offer, but make sure that kqueue is used if	479	Use whatever libev has to offer, but make sure that kqueue is used if
459	available (warning, breaks stuff, best use only with your own private	480	available (warning, breaks stuff, best use only with your own private
460	event loop and only if you know the OS supports your types of fds):	481	event loop and only if you know the OS supports your types of fds):
461		482
462	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	483	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
463		484
464	=item struct ev_loop *ev_loop_new (unsigned int flags)	485	=item struct ev_loop *ev_loop_new (unsigned int flags)
465		486
466	Similar to C<ev_default_loop>, but always creates a new event loop that is	487	Similar to C<ev_default_loop>, but always creates a new event loop that is
467	always distinct from the default loop. Unlike the default loop, it cannot	488	always distinct from the default loop. Unlike the default loop, it cannot
…		…
472	libev with threads is indeed to create one loop per thread, and using the	493	libev with threads is indeed to create one loop per thread, and using the
473	default loop in the "main" or "initial" thread.	494	default loop in the "main" or "initial" thread.
474		495
475	Example: Try to create a event loop that uses epoll and nothing else.	496	Example: Try to create a event loop that uses epoll and nothing else.
476		497
477	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	498	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
478	if (!epoller)	499	if (!epoller)
479	fatal ("no epoll found here, maybe it hides under your chair");	500	fatal ("no epoll found here, maybe it hides under your chair");
480		501
481	=item ev_default_destroy ()	502	=item ev_default_destroy ()
482		503
483	Destroys the default loop again (frees all memory and kernel state	504	Destroys the default loop again (frees all memory and kernel state
484	etc.). None of the active event watchers will be stopped in the normal	505	etc.). None of the active event watchers will be stopped in the normal
485	sense, so e.g. C<ev_is_active> might still return true. It is your	506	sense, so e.g. C<ev_is_active> might still return true. It is your
486	responsibility to either stop all watchers cleanly yoursef I<before>	507	responsibility to either stop all watchers cleanly yourself I<before>
487	calling this function, or cope with the fact afterwards (which is usually	508	calling this function, or cope with the fact afterwards (which is usually
488	the easiest thing, you can just ignore the watchers and/or C<free ()> them	509	the easiest thing, you can just ignore the watchers and/or C<free ()> them
489	for example).	510	for example).
490		511
491	Note that certain global state, such as signal state, will not be freed by	512	Note that certain global state, such as signal state, will not be freed by
…		…
572	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	593	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle
573	those events and any outstanding ones, but will not block your process in	594	those events and any outstanding ones, but will not block your process in
574	case there are no events and will return after one iteration of the loop.	595	case there are no events and will return after one iteration of the loop.
575		596
576	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	597	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
577	neccessary) and will handle those and any outstanding ones. It will block	598	necessary) and will handle those and any outstanding ones. It will block
578	your process until at least one new event arrives, and will return after	599	your process until at least one new event arrives, and will return after
579	one iteration of the loop. This is useful if you are waiting for some	600	one iteration of the loop. This is useful if you are waiting for some
580	external event in conjunction with something not expressible using other	601	external event in conjunction with something not expressible using other
581	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	602	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
582	usually a better approach for this kind of thing.	603	usually a better approach for this kind of thing.
…		…
643	respectively).	664	respectively).
644		665
645	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	666	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
646	running when nothing else is active.	667	running when nothing else is active.
647		668
648	struct ev_signal exitsig;	669	struct ev_signal exitsig;
649	ev_signal_init (&exitsig, sig_cb, SIGINT);	670	ev_signal_init (&exitsig, sig_cb, SIGINT);
650	ev_signal_start (loop, &exitsig);	671	ev_signal_start (loop, &exitsig);
651	evf_unref (loop);	672	evf_unref (loop);
652		673
653	Example: For some weird reason, unregister the above signal handler again.	674	Example: For some weird reason, unregister the above signal handler again.
654		675
655	ev_ref (loop);	676	ev_ref (loop);
656	ev_signal_stop (loop, &exitsig);	677	ev_signal_stop (loop, &exitsig);
657		678
658	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	679	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
659		680
660	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	681	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
661		682
…		…
683	to spend more time collecting timeouts, at the expense of increased	704	to spend more time collecting timeouts, at the expense of increased
684	latency (the watcher callback will be called later). C<ev_io> watchers	705	latency (the watcher callback will be called later). C<ev_io> watchers
685	will not be affected. Setting this to a non-null value will not introduce	706	will not be affected. Setting this to a non-null value will not introduce
686	any overhead in libev.	707	any overhead in libev.
687		708
688	Many (busy) programs can usually benefit by setting the io collect	709	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	710	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	711	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>,	712	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.	713	as this approaches the timing granularity of most systems.
693		714
694	=item ev_loop_verify (loop)	715	=item ev_loop_verify (loop)
695		716
696	This function only does something when C<EV_VERIFY> support has been	717	This function only does something when C<EV_VERIFY> support has been
697	compiled in. It tries to go through all internal structures and checks	718	compiled in. It tries to go through all internal structures and checks
…		…
709		730
710	A watcher is a structure that you create and register to record your	731	A watcher is a structure that you create and register to record your
711	interest in some event. For instance, if you want to wait for STDIN to	732	interest in some event. For instance, if you want to wait for STDIN to
712	become readable, you would create an C<ev_io> watcher for that:	733	become readable, you would create an C<ev_io> watcher for that:
713		734
714	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	735	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
715	{	736	{
716	ev_io_stop (w);	737	ev_io_stop (w);
717	ev_unloop (loop, EVUNLOOP_ALL);	738	ev_unloop (loop, EVUNLOOP_ALL);
718	}	739	}
719		740
720	struct ev_loop *loop = ev_default_loop (0);	741	struct ev_loop *loop = ev_default_loop (0);
721	struct ev_io stdin_watcher;	742	struct ev_io stdin_watcher;
722	ev_init (&stdin_watcher, my_cb);	743	ev_init (&stdin_watcher, my_cb);
723	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	744	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
724	ev_io_start (loop, &stdin_watcher);	745	ev_io_start (loop, &stdin_watcher);
725	ev_loop (loop, 0);	746	ev_loop (loop, 0);
726		747
727	As you can see, you are responsible for allocating the memory for your	748	As you can see, you are responsible for allocating the memory for your
728	watcher structures (and it is usually a bad idea to do this on the stack,	749	watcher structures (and it is usually a bad idea to do this on the stack,
729	although this can sometimes be quite valid).	750	although this can sometimes be quite valid).
730		751
731	Each watcher structure must be initialised by a call to C<ev_init	752	Each watcher structure must be initialised by a call to C<ev_init
732	(watcher *, callback)>, which expects a callback to be provided. This	753	(watcher *, callback)>, which expects a callback to be provided. This
733	callback gets invoked each time the event occurs (or, in the case of io	754	callback gets invoked each time the event occurs (or, in the case of I/O
734	watchers, each time the event loop detects that the file descriptor given	755	watchers, each time the event loop detects that the file descriptor given
735	is readable and/or writable).	756	is readable and/or writable).
736		757
737	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	758	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro
738	with arguments specific to this watcher type. There is also a macro	759	with arguments specific to this watcher type. There is also a macro
…		…
814		835
815	The given async watcher has been asynchronously notified (see C<ev_async>).	836	The given async watcher has been asynchronously notified (see C<ev_async>).
816		837
817	=item C<EV_ERROR>	838	=item C<EV_ERROR>
818		839
819	An unspecified error has occured, the watcher has been stopped. This might	840	An unspecified error has occurred, the watcher has been stopped. This might
820	happen because the watcher could not be properly started because libev	841	happen because the watcher could not be properly started because libev
821	ran out of memory, a file descriptor was found to be closed or any other	842	ran out of memory, a file descriptor was found to be closed or any other
822	problem. You best act on it by reporting the problem and somehow coping	843	problem. You best act on it by reporting the problem and somehow coping
823	with the watcher being stopped.	844	with the watcher being stopped.
824		845
825	Libev will usually signal a few "dummy" events together with an error,	846	Libev will usually signal a few "dummy" events together with an error,
826	for example it might indicate that a fd is readable or writable, and if	847	for example it might indicate that a fd is readable or writable, and if
827	your callbacks is well-written it can just attempt the operation and cope	848	your callbacks is well-written it can just attempt the operation and cope
828	with the error from read() or write(). This will not work in multithreaded	849	with the error from read() or write(). This will not work in multi-threaded
829	programs, though, so beware.	850	programs, though, so beware.
830		851
831	=back	852	=back
832		853
833	=head2 GENERIC WATCHER FUNCTIONS	854	=head2 GENERIC WATCHER FUNCTIONS
…		…
863	Although some watcher types do not have type-specific arguments	884	Although some watcher types do not have type-specific arguments
864	(e.g. C<ev_prepare>) you still need to call its C<set> macro.	885	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
865		886
866	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	887	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
867		888
868	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	889	This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
869	calls into a single call. This is the most convinient method to initialise	890	calls into a single call. This is the most convenient method to initialise
870	a watcher. The same limitations apply, of course.	891	a watcher. The same limitations apply, of course.
871		892
872	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	893	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
873		894
874	Starts (activates) the given watcher. Only active watchers will receive	895	Starts (activates) the given watcher. Only active watchers will receive
…		…
957	to associate arbitrary data with your watcher. If you need more data and	978	to associate arbitrary data with your watcher. If you need more data and
958	don't want to allocate memory and store a pointer to it in that data	979	don't want to allocate memory and store a pointer to it in that data
959	member, you can also "subclass" the watcher type and provide your own	980	member, you can also "subclass" the watcher type and provide your own
960	data:	981	data:
961		982
962	struct my_io	983	struct my_io
963	{	984	{
964	struct ev_io io;	985	struct ev_io io;
965	int otherfd;	986	int otherfd;
966	void *somedata;	987	void *somedata;
967	struct whatever *mostinteresting;	988	struct whatever *mostinteresting;
968	}	989	}
969		990
970	And since your callback will be called with a pointer to the watcher, you	991	And since your callback will be called with a pointer to the watcher, you
971	can cast it back to your own type:	992	can cast it back to your own type:
972		993
973	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	994	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
974	{	995	{
975	struct my_io *w = (struct my_io *)w_;	996	struct my_io *w = (struct my_io *)w_;
976	...	997	...
977	}	998	}
978		999
979	More interesting and less C-conformant ways of casting your callback type	1000	More interesting and less C-conformant ways of casting your callback type
980	instead have been omitted.	1001	instead have been omitted.
981		1002
982	Another common scenario is having some data structure with multiple	1003	Another common scenario is having some data structure with multiple
983	watchers:	1004	watchers:
984		1005
985	struct my_biggy	1006	struct my_biggy
986	{	1007	{
987	int some_data;	1008	int some_data;
988	ev_timer t1;	1009	ev_timer t1;
989	ev_timer t2;	1010	ev_timer t2;
990	}	1011	}
991		1012
992	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1013	In this case getting the pointer to C<my_biggy> is a bit more complicated,
993	you need to use C<offsetof>:	1014	you need to use C<offsetof>:
994		1015
995	#include <stddef.h>	1016	#include <stddef.h>
996		1017
997	static void	1018	static void
998	t1_cb (EV_P_ struct ev_timer *w, int revents)	1019	t1_cb (EV_P_ struct ev_timer *w, int revents)
999	{	1020	{
1000	struct my_biggy big = (struct my_biggy *	1021	struct my_biggy big = (struct my_biggy *
1001	(((char *)w) - offsetof (struct my_biggy, t1));	1022	(((char *)w) - offsetof (struct my_biggy, t1));
1002	}	1023	}
1003		1024
1004	static void	1025	static void
1005	t2_cb (EV_P_ struct ev_timer *w, int revents)	1026	t2_cb (EV_P_ struct ev_timer *w, int revents)
1006	{	1027	{
1007	struct my_biggy big = (struct my_biggy *	1028	struct my_biggy big = (struct my_biggy *
1008	(((char *)w) - offsetof (struct my_biggy, t2));	1029	(((char *)w) - offsetof (struct my_biggy, t2));
1009	}	1030	}
1010		1031
1011		1032
1012	=head1 WATCHER TYPES	1033	=head1 WATCHER TYPES
1013		1034
1014	This section describes each watcher in detail, but will not repeat	1035	This section describes each watcher in detail, but will not repeat
…		…
1046		1067
1047	Another thing you have to watch out for is that it is quite easy to	1068	Another thing you have to watch out for is that it is quite easy to
1048	receive "spurious" readiness notifications, that is your callback might	1069	receive "spurious" readiness notifications, that is your callback might
1049	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1070	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1050	because there is no data. Not only are some backends known to create a	1071	because there is no data. Not only are some backends known to create a
1051	lot of those (for example solaris ports), it is very easy to get into	1072	lot of those (for example Solaris ports), it is very easy to get into
1052	this situation even with a relatively standard program structure. Thus	1073	this situation even with a relatively standard program structure. Thus
1053	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1074	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1054	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1075	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1055		1076
1056	If you cannot run the fd in non-blocking mode (for example you should not	1077	If you cannot run the fd in non-blocking mode (for example you should not
1057	play around with an Xlib connection), then you have to seperately re-test	1078	play around with an Xlib connection), then you have to separately re-test
1058	whether a file descriptor is really ready with a known-to-be good interface	1079	whether a file descriptor is really ready with a known-to-be good interface
1059	such as poll (fortunately in our Xlib example, Xlib already does this on	1080	such as poll (fortunately in our Xlib example, Xlib already does this on
1060	its own, so its quite safe to use).	1081	its own, so its quite safe to use).
1061		1082
1062	=head3 The special problem of disappearing file descriptors	1083	=head3 The special problem of disappearing file descriptors
…		…
1122	=item ev_io_init (ev_io *, callback, int fd, int events)	1143	=item ev_io_init (ev_io *, callback, int fd, int events)
1123		1144
1124	=item ev_io_set (ev_io *, int fd, int events)	1145	=item ev_io_set (ev_io *, int fd, int events)
1125		1146
1126	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1147	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1127	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1148	receive events for and events is either C<EV_READ>, C<EV_WRITE> or
1128	C<EV_READ | EV_WRITE> to receive the given events.	1149	C<EV_READ | EV_WRITE> to receive the given events.
1129		1150
1130	=item int fd [read-only]	1151	=item int fd [read-only]
1131		1152
1132	The file descriptor being watched.	1153	The file descriptor being watched.
…		…
1141		1162
1142	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1163	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1143	readable, but only once. Since it is likely line-buffered, you could	1164	readable, but only once. Since it is likely line-buffered, you could
1144	attempt to read a whole line in the callback.	1165	attempt to read a whole line in the callback.
1145		1166
1146	static void	1167	static void
1147	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1168	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1148	{	1169	{
1149	ev_io_stop (loop, w);	1170	ev_io_stop (loop, w);
1150	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1171	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1151	}	1172	}
1152		1173
1153	...	1174	...
1154	struct ev_loop *loop = ev_default_init (0);	1175	struct ev_loop *loop = ev_default_init (0);
1155	struct ev_io stdin_readable;	1176	struct ev_io stdin_readable;
1156	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1177	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1157	ev_io_start (loop, &stdin_readable);	1178	ev_io_start (loop, &stdin_readable);
1158	ev_loop (loop, 0);	1179	ev_loop (loop, 0);
1159		1180
1160		1181
1161	=head2 C<ev_timer> - relative and optionally repeating timeouts	1182	=head2 C<ev_timer> - relative and optionally repeating timeouts
1162		1183
1163	Timer watchers are simple relative timers that generate an event after a	1184	Timer watchers are simple relative timers that generate an event after a
1164	given time, and optionally repeating in regular intervals after that.	1185	given time, and optionally repeating in regular intervals after that.
1165		1186
1166	The timers are based on real time, that is, if you register an event that	1187	The timers are based on real time, that is, if you register an event that
1167	times out after an hour and you reset your system clock to january last	1188	times out after an hour and you reset your system clock to January last
1168	year, it will still time out after (roughly) and hour. "Roughly" because	1189	year, it will still time out after (roughly) and hour. "Roughly" because
1169	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1190	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1170	monotonic clock option helps a lot here).	1191	monotonic clock option helps a lot here).
1171		1192
1172	The relative timeouts are calculated relative to the C<ev_now ()>	1193	The relative timeouts are calculated relative to the C<ev_now ()>
…		…
1175	you suspect event processing to be delayed and you I<need> to base the timeout	1196	you suspect event processing to be delayed and you I<need> to base the timeout
1176	on the current time, use something like this to adjust for this:	1197	on the current time, use something like this to adjust for this:
1177		1198
1178	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1199	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1179		1200
1180	The callback is guarenteed to be invoked only after its timeout has passed,	1201	The callback is guaranteed to be invoked only after its timeout has passed,
1181	but if multiple timers become ready during the same loop iteration then	1202	but if multiple timers become ready during the same loop iteration then
1182	order of execution is undefined.	1203	order of execution is undefined.
1183		1204
1184	=head3 Watcher-Specific Functions and Data Members	1205	=head3 Watcher-Specific Functions and Data Members
1185		1206
…		…
1206	This will act as if the timer timed out and restart it again if it is	1227	This will act as if the timer timed out and restart it again if it is
1207	repeating. The exact semantics are:	1228	repeating. The exact semantics are:
1208		1229
1209	If the timer is pending, its pending status is cleared.	1230	If the timer is pending, its pending status is cleared.
1210		1231
1211	If the timer is started but nonrepeating, stop it (as if it timed out).	1232	If the timer is started but non-repeating, stop it (as if it timed out).
1212		1233
1213	If the timer is repeating, either start it if necessary (with the	1234	If the timer is repeating, either start it if necessary (with the
1214	C<repeat> value), or reset the running timer to the C<repeat> value.	1235	C<repeat> value), or reset the running timer to the C<repeat> value.
1215		1236
1216	This sounds a bit complicated, but here is a useful and typical	1237	This sounds a bit complicated, but here is a useful and typical
1217	example: Imagine you have a tcp connection and you want a so-called idle	1238	example: Imagine you have a TCP connection and you want a so-called idle
1218	timeout, that is, you want to be called when there have been, say, 60	1239	timeout, that is, you want to be called when there have been, say, 60
1219	seconds of inactivity on the socket. The easiest way to do this is to	1240	seconds of inactivity on the socket. The easiest way to do this is to
1220	configure an C<ev_timer> with a C<repeat> value of C<60> and then call	1241	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1221	C<ev_timer_again> each time you successfully read or write some data. If	1242	C<ev_timer_again> each time you successfully read or write some data. If
1222	you go into an idle state where you do not expect data to travel on the	1243	you go into an idle state where you do not expect data to travel on the
…		…
1248		1269
1249	=head3 Examples	1270	=head3 Examples
1250		1271
1251	Example: Create a timer that fires after 60 seconds.	1272	Example: Create a timer that fires after 60 seconds.
1252		1273
1253	static void	1274	static void
1254	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1275	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1255	{	1276	{
1256	.. one minute over, w is actually stopped right here	1277	.. one minute over, w is actually stopped right here
1257	}	1278	}
1258		1279
1259	struct ev_timer mytimer;	1280	struct ev_timer mytimer;
1260	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1281	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1261	ev_timer_start (loop, &mytimer);	1282	ev_timer_start (loop, &mytimer);
1262		1283
1263	Example: Create a timeout timer that times out after 10 seconds of	1284	Example: Create a timeout timer that times out after 10 seconds of
1264	inactivity.	1285	inactivity.
1265		1286
1266	static void	1287	static void
1267	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1288	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1268	{	1289	{
1269	.. ten seconds without any activity	1290	.. ten seconds without any activity
1270	}	1291	}
1271		1292
1272	struct ev_timer mytimer;	1293	struct ev_timer mytimer;
1273	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1294	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1274	ev_timer_again (&mytimer); /* start timer */	1295	ev_timer_again (&mytimer); /* start timer */
1275	ev_loop (loop, 0);	1296	ev_loop (loop, 0);
1276		1297
1277	// and in some piece of code that gets executed on any "activity":	1298	// and in some piece of code that gets executed on any "activity":
1278	// reset the timeout to start ticking again at 10 seconds	1299	// reset the timeout to start ticking again at 10 seconds
1279	ev_timer_again (&mytimer);	1300	ev_timer_again (&mytimer);
1280		1301
1281		1302
1282	=head2 C<ev_periodic> - to cron or not to cron?	1303	=head2 C<ev_periodic> - to cron or not to cron?
1283		1304
1284	Periodic watchers are also timers of a kind, but they are very versatile	1305	Periodic watchers are also timers of a kind, but they are very versatile
1285	(and unfortunately a bit complex).	1306	(and unfortunately a bit complex).
1286		1307
1287	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1308	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
1288	but on wallclock time (absolute time). You can tell a periodic watcher	1309	but on wall clock time (absolute time). You can tell a periodic watcher
1289	to trigger after some specific point in time. For example, if you tell a	1310	to trigger after some specific point in time. For example, if you tell a
1290	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1311	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()
1291	+ 10.>, that is, an absolute time not a delay) and then reset your system	1312	+ 10.>, that is, an absolute time not a delay) and then reset your system
1292	clock to january of the previous year, then it will take more than year	1313	clock to January of the previous year, then it will take more than year
1293	to trigger the event (unlike an C<ev_timer>, which would still trigger	1314	to trigger the event (unlike an C<ev_timer>, which would still trigger
1294	roughly 10 seconds later as it uses a relative timeout).	1315	roughly 10 seconds later as it uses a relative timeout).
1295		1316
1296	C<ev_periodic>s can also be used to implement vastly more complex timers,	1317	C<ev_periodic>s can also be used to implement vastly more complex timers,
1297	such as triggering an event on each "midnight, local time", or other	1318	such as triggering an event on each "midnight, local time", or other
1298	complicated, rules.	1319	complicated, rules.
1299		1320
1300	As with timers, the callback is guarenteed to be invoked only when the	1321	As with timers, the callback is guaranteed to be invoked only when the
1301	time (C<at>) has passed, but if multiple periodic timers become ready	1322	time (C<at>) has passed, but if multiple periodic timers become ready
1302	during the same loop iteration then order of execution is undefined.	1323	during the same loop iteration then order of execution is undefined.
1303		1324
1304	=head3 Watcher-Specific Functions and Data Members	1325	=head3 Watcher-Specific Functions and Data Members
1305		1326
…		…
1314		1335
1315	=over 4	1336	=over 4
1316		1337
1317	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1338	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1318		1339
1319	In this configuration the watcher triggers an event after the wallclock	1340	In this configuration the watcher triggers an event after the wall clock
1320	time C<at> has passed and doesn't repeat. It will not adjust when a time	1341	time C<at> has passed and doesn't repeat. It will not adjust when a time
1321	jump occurs, that is, if it is to be run at January 1st 2011 then it will	1342	jump occurs, that is, if it is to be run at January 1st 2011 then it will
1322	run when the system time reaches or surpasses this time.	1343	run when the system time reaches or surpasses this time.
1323		1344
1324	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1345	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
…		…
1332	the hour:	1353	the hour:
1333		1354
1334	ev_periodic_set (&periodic, 0., 3600., 0);	1355	ev_periodic_set (&periodic, 0., 3600., 0);
1335		1356
1336	This doesn't mean there will always be 3600 seconds in between triggers,	1357	This doesn't mean there will always be 3600 seconds in between triggers,
1337	but only that the the callback will be called when the system time shows a	1358	but only that the callback will be called when the system time shows a
1338	full hour (UTC), or more correctly, when the system time is evenly divisible	1359	full hour (UTC), or more correctly, when the system time is evenly divisible
1339	by 3600.	1360	by 3600.
1340		1361
1341	Another way to think about it (for the mathematically inclined) is that	1362	Another way to think about it (for the mathematically inclined) is that
1342	C<ev_periodic> will try to run the callback in this mode at the next possible	1363	C<ev_periodic> will try to run the callback in this mode at the next possible
…		…
1344		1365
1345	For numerical stability it is preferable that the C<at> value is near	1366	For numerical stability it is preferable that the C<at> value is near
1346	C<ev_now ()> (the current time), but there is no range requirement for	1367	C<ev_now ()> (the current time), but there is no range requirement for
1347	this value, and in fact is often specified as zero.	1368	this value, and in fact is often specified as zero.
1348		1369
1349	Note also that there is an upper limit to how often a timer can fire (cpu	1370	Note also that there is an upper limit to how often a timer can fire (CPU
1350	speed for example), so if C<interval> is very small then timing stability	1371	speed for example), so if C<interval> is very small then timing stability
1351	will of course detoriate. Libev itself tries to be exact to be about one	1372	will of course deteriorate. Libev itself tries to be exact to be about one
1352	millisecond (if the OS supports it and the machine is fast enough).	1373	millisecond (if the OS supports it and the machine is fast enough).
1353		1374
1354	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1375	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1355		1376
1356	In this mode the values for C<interval> and C<at> are both being	1377	In this mode the values for C<interval> and C<at> are both being
…		…
1425		1446
1426	=head3 Examples	1447	=head3 Examples
1427		1448
1428	Example: Call a callback every hour, or, more precisely, whenever the	1449	Example: Call a callback every hour, or, more precisely, whenever the
1429	system clock is divisible by 3600. The callback invocation times have	1450	system clock is divisible by 3600. The callback invocation times have
1430	potentially a lot of jittering, but good long-term stability.	1451	potentially a lot of jitter, but good long-term stability.
1431		1452
1432	static void	1453	static void
1433	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1454	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1434	{	1455	{
1435	... its now a full hour (UTC, or TAI or whatever your clock follows)	1456	... its now a full hour (UTC, or TAI or whatever your clock follows)
1436	}	1457	}
1437		1458
1438	struct ev_periodic hourly_tick;	1459	struct ev_periodic hourly_tick;
1439	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1460	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1440	ev_periodic_start (loop, &hourly_tick);	1461	ev_periodic_start (loop, &hourly_tick);
1441		1462
1442	Example: The same as above, but use a reschedule callback to do it:	1463	Example: The same as above, but use a reschedule callback to do it:
1443		1464
1444	#include <math.h>	1465	#include <math.h>
1445		1466
1446	static ev_tstamp	1467	static ev_tstamp
1447	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1468	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1448	{	1469	{
1449	return fmod (now, 3600.) + 3600.;	1470	return fmod (now, 3600.) + 3600.;
1450	}	1471	}
1451		1472
1452	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1473	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1453		1474
1454	Example: Call a callback every hour, starting now:	1475	Example: Call a callback every hour, starting now:
1455		1476
1456	struct ev_periodic hourly_tick;	1477	struct ev_periodic hourly_tick;
1457	ev_periodic_init (&hourly_tick, clock_cb,	1478	ev_periodic_init (&hourly_tick, clock_cb,
1458	fmod (ev_now (loop), 3600.), 3600., 0);	1479	fmod (ev_now (loop), 3600.), 3600., 0);
1459	ev_periodic_start (loop, &hourly_tick);	1480	ev_periodic_start (loop, &hourly_tick);
1460		1481
1461		1482
1462	=head2 C<ev_signal> - signal me when a signal gets signalled!	1483	=head2 C<ev_signal> - signal me when a signal gets signalled!
1463		1484
1464	Signal watchers will trigger an event when the process receives a specific	1485	Signal watchers will trigger an event when the process receives a specific
…		…
1472	as you don't register any with libev). Similarly, when the last signal	1493	as you don't register any with libev). Similarly, when the last signal
1473	watcher for a signal is stopped libev will reset the signal handler to	1494	watcher for a signal is stopped libev will reset the signal handler to
1474	SIG_DFL (regardless of what it was set to before).	1495	SIG_DFL (regardless of what it was set to before).
1475		1496
1476	If possible and supported, libev will install its handlers with	1497	If possible and supported, libev will install its handlers with
1477	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1498	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1478	interrupted. If you have a problem with syscalls getting interrupted by	1499	interrupted. If you have a problem with system calls getting interrupted by
1479	signals you can block all signals in an C<ev_check> watcher and unblock	1500	signals you can block all signals in an C<ev_check> watcher and unblock
1480	them in an C<ev_prepare> watcher.	1501	them in an C<ev_prepare> watcher.
1481		1502
1482	=head3 Watcher-Specific Functions and Data Members	1503	=head3 Watcher-Specific Functions and Data Members
1483		1504
…		…
1498		1519
1499	=head3 Examples	1520	=head3 Examples
1500		1521
1501	Example: Try to exit cleanly on SIGINT and SIGTERM.	1522	Example: Try to exit cleanly on SIGINT and SIGTERM.
1502		1523
1503	static void	1524	static void
1504	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1525	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1505	{	1526	{
1506	ev_unloop (loop, EVUNLOOP_ALL);	1527	ev_unloop (loop, EVUNLOOP_ALL);
1507	}	1528	}
1508		1529
1509	struct ev_signal signal_watcher;	1530	struct ev_signal signal_watcher;
1510	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1531	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1511	ev_signal_start (loop, &sigint_cb);	1532	ev_signal_start (loop, &sigint_cb);
1512		1533
1513		1534
1514	=head2 C<ev_child> - watch out for process status changes	1535	=head2 C<ev_child> - watch out for process status changes
1515		1536
1516	Child watchers trigger when your process receives a SIGCHLD in response to	1537	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1518	is permissible to install a child watcher I<after> the child has been	1539	is permissible to install a child watcher I<after> the child has been
1519	forked (which implies it might have already exited), as long as the event	1540	forked (which implies it might have already exited), as long as the event
1520	loop isn't entered (or is continued from a watcher).	1541	loop isn't entered (or is continued from a watcher).
1521		1542
1522	Only the default event loop is capable of handling signals, and therefore	1543	Only the default event loop is capable of handling signals, and therefore
1523	you can only rgeister child watchers in the default event loop.	1544	you can only register child watchers in the default event loop.
1524		1545
1525	=head3 Process Interaction	1546	=head3 Process Interaction
1526		1547
1527	Libev grabs C<SIGCHLD> as soon as the default event loop is	1548	Libev grabs C<SIGCHLD> as soon as the default event loop is
1528	initialised. This is necessary to guarantee proper behaviour even if	1549	initialised. This is necessary to guarantee proper behaviour even if
1529	the first child watcher is started after the child exits. The occurance	1550	the first child watcher is started after the child exits. The occurrence
1530	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1551	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1531	synchronously as part of the event loop processing. Libev always reaps all	1552	synchronously as part of the event loop processing. Libev always reaps all
1532	children, even ones not watched.	1553	children, even ones not watched.
1533		1554
1534	=head3 Overriding the Built-In Processing	1555	=head3 Overriding the Built-In Processing
…		…
1576	=head3 Examples	1597	=head3 Examples
1577		1598
1578	Example: C<fork()> a new process and install a child handler to wait for	1599	Example: C<fork()> a new process and install a child handler to wait for
1579	its completion.	1600	its completion.
1580		1601
1581	ev_child cw;	1602	ev_child cw;
1582		1603
1583	static void	1604	static void
1584	child_cb (EV_P_ struct ev_child *w, int revents)	1605	child_cb (EV_P_ struct ev_child *w, int revents)
1585	{	1606	{
1586	ev_child_stop (EV_A_ w);	1607	ev_child_stop (EV_A_ w);
1587	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1608	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1588	}	1609	}
1589		1610
1590	pid_t pid = fork ();	1611	pid_t pid = fork ();
1591		1612
1592	if (pid < 0)	1613	if (pid < 0)
1593	// error	1614	// error
1594	else if (pid == 0)	1615	else if (pid == 0)
1595	{	1616	{
1596	// the forked child executes here	1617	// the forked child executes here
1597	exit (1);	1618	exit (1);
1598	}	1619	}
1599	else	1620	else
1600	{	1621	{
1601	ev_child_init (&cw, child_cb, pid, 0);	1622	ev_child_init (&cw, child_cb, pid, 0);
1602	ev_child_start (EV_DEFAULT_ &cw);	1623	ev_child_start (EV_DEFAULT_ &cw);
1603	}	1624	}
1604		1625
1605		1626
1606	=head2 C<ev_stat> - did the file attributes just change?	1627	=head2 C<ev_stat> - did the file attributes just change?
1607		1628
1608	This watches a filesystem path for attribute changes. That is, it calls	1629	This watches a file system path for attribute changes. That is, it calls
1609	C<stat> regularly (or when the OS says it changed) and sees if it changed	1630	C<stat> regularly (or when the OS says it changed) and sees if it changed
1610	compared to the last time, invoking the callback if it did.	1631	compared to the last time, invoking the callback if it did.
1611		1632
1612	The path does not need to exist: changing from "path exists" to "path does	1633	The path does not need to exist: changing from "path exists" to "path does
1613	not exist" is a status change like any other. The condition "path does	1634	not exist" is a status change like any other. The condition "path does
…		…
1647	disabled large file support, you get the 32 bit version of the stat	1668	disabled large file support, you get the 32 bit version of the stat
1648	structure. When using the library from programs that change the ABI to	1669	structure. When using the library from programs that change the ABI to
1649	use 64 bit file offsets the programs will fail. In that case you have to	1670	use 64 bit file offsets the programs will fail. In that case you have to
1650	compile libev with the same flags to get binary compatibility. This is	1671	compile libev with the same flags to get binary compatibility. This is
1651	obviously the case with any flags that change the ABI, but the problem is	1672	obviously the case with any flags that change the ABI, but the problem is
1652	most noticably with ev_stat and largefile support.	1673	most noticeably with ev_stat and large file support.
1653		1674
1654	=head3 Inotify	1675	=head3 Inotify
1655		1676
1656	When C<inotify (7)> support has been compiled into libev (generally only	1677	When C<inotify (7)> support has been compiled into libev (generally only
1657	available on Linux) and present at runtime, it will be used to speed up	1678	available on Linux) and present at runtime, it will be used to speed up
…		…
1667	implement this functionality, due to the requirement of having a file	1688	implement this functionality, due to the requirement of having a file
1668	descriptor open on the object at all times).	1689	descriptor open on the object at all times).
1669		1690
1670	=head3 The special problem of stat time resolution	1691	=head3 The special problem of stat time resolution
1671		1692
1672	The C<stat ()> syscall only supports full-second resolution portably, and	1693	The C<stat ()> system call only supports full-second resolution portably, and
1673	even on systems where the resolution is higher, many filesystems still	1694	even on systems where the resolution is higher, many file systems still
1674	only support whole seconds.	1695	only support whole seconds.
1675		1696
1676	That means that, if the time is the only thing that changes, you can	1697	That means that, if the time is the only thing that changes, you can
1677	easily miss updates: on the first update, C<ev_stat> detects a change and	1698	easily miss updates: on the first update, C<ev_stat> detects a change and
1678	calls your callback, which does something. When there is another update	1699	calls your callback, which does something. When there is another update
…		…
1738		1759
1739	The specified interval.	1760	The specified interval.
1740		1761
1741	=item const char *path [read-only]	1762	=item const char *path [read-only]
1742		1763
1743	The filesystem path that is being watched.	1764	The file system path that is being watched.
1744		1765
1745	=back	1766	=back
1746		1767
1747	=head3 Examples	1768	=head3 Examples
1748		1769
1749	Example: Watch C</etc/passwd> for attribute changes.	1770	Example: Watch C</etc/passwd> for attribute changes.
1750		1771
1751	static void	1772	static void
1752	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1773	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1753	{	1774	{
1754	/* /etc/passwd changed in some way */	1775	/* /etc/passwd changed in some way */
1755	if (w->attr.st_nlink)	1776	if (w->attr.st_nlink)
1756	{	1777	{
1757	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1778	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1758	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1779	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1759	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1780	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1760	}	1781	}
1761	else	1782	else
1762	/* you shalt not abuse printf for puts */	1783	/* you shalt not abuse printf for puts */
1763	puts ("wow, /etc/passwd is not there, expect problems. "	1784	puts ("wow, /etc/passwd is not there, expect problems. "
1764	"if this is windows, they already arrived\n");	1785	"if this is windows, they already arrived\n");
1765	}	1786	}
1766		1787
1767	...	1788	...
1768	ev_stat passwd;	1789	ev_stat passwd;
1769		1790
1770	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1791	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1771	ev_stat_start (loop, &passwd);	1792	ev_stat_start (loop, &passwd);
1772		1793
1773	Example: Like above, but additionally use a one-second delay so we do not	1794	Example: Like above, but additionally use a one-second delay so we do not
1774	miss updates (however, frequent updates will delay processing, too, so	1795	miss updates (however, frequent updates will delay processing, too, so
1775	one might do the work both on C<ev_stat> callback invocation I<and> on	1796	one might do the work both on C<ev_stat> callback invocation I<and> on
1776	C<ev_timer> callback invocation).	1797	C<ev_timer> callback invocation).
1777		1798
1778	static ev_stat passwd;	1799	static ev_stat passwd;
1779	static ev_timer timer;	1800	static ev_timer timer;
1780		1801
1781	static void	1802	static void
1782	timer_cb (EV_P_ ev_timer *w, int revents)	1803	timer_cb (EV_P_ ev_timer *w, int revents)
1783	{	1804	{
1784	ev_timer_stop (EV_A_ w);	1805	ev_timer_stop (EV_A_ w);
1785		1806
1786	/* now it's one second after the most recent passwd change */	1807	/* now it's one second after the most recent passwd change */
1787	}	1808	}
1788		1809
1789	static void	1810	static void
1790	stat_cb (EV_P_ ev_stat *w, int revents)	1811	stat_cb (EV_P_ ev_stat *w, int revents)
1791	{	1812	{
1792	/* reset the one-second timer */	1813	/* reset the one-second timer */
1793	ev_timer_again (EV_A_ &timer);	1814	ev_timer_again (EV_A_ &timer);
1794	}	1815	}
1795		1816
1796	...	1817	...
1797	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1818	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1798	ev_stat_start (loop, &passwd);	1819	ev_stat_start (loop, &passwd);
1799	ev_timer_init (&timer, timer_cb, 0., 1.02);	1820	ev_timer_init (&timer, timer_cb, 0., 1.02);
1800		1821
1801		1822
1802	=head2 C<ev_idle> - when you've got nothing better to do...	1823	=head2 C<ev_idle> - when you've got nothing better to do...
1803		1824
1804	Idle watchers trigger events when no other events of the same or higher	1825	Idle watchers trigger events when no other events of the same or higher
…		…
1835	=head3 Examples	1856	=head3 Examples
1836		1857
1837	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1858	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1838	callback, free it. Also, use no error checking, as usual.	1859	callback, free it. Also, use no error checking, as usual.
1839		1860
1840	static void	1861	static void
1841	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1862	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1842	{	1863	{
1843	free (w);	1864	free (w);
1844	// now do something you wanted to do when the program has	1865	// now do something you wanted to do when the program has
1845	// no longer anything immediate to do.	1866	// no longer anything immediate to do.
1846	}	1867	}
1847		1868
1848	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1869	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1849	ev_idle_init (idle_watcher, idle_cb);	1870	ev_idle_init (idle_watcher, idle_cb);
1850	ev_idle_start (loop, idle_cb);	1871	ev_idle_start (loop, idle_cb);
1851		1872
1852		1873
1853	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1874	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1854		1875
1855	Prepare and check watchers are usually (but not always) used in tandem:	1876	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1874		1895
1875	This is done by examining in each prepare call which file descriptors need	1896	This is done by examining in each prepare call which file descriptors need
1876	to be watched by the other library, registering C<ev_io> watchers for	1897	to be watched by the other library, registering C<ev_io> watchers for
1877	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1898	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1878	provide just this functionality). Then, in the check watcher you check for	1899	provide just this functionality). Then, in the check watcher you check for
1879	any events that occured (by checking the pending status of all watchers	1900	any events that occurred (by checking the pending status of all watchers
1880	and stopping them) and call back into the library. The I/O and timer	1901	and stopping them) and call back into the library. The I/O and timer
1881	callbacks will never actually be called (but must be valid nevertheless,	1902	callbacks will never actually be called (but must be valid nevertheless,
1882	because you never know, you know?).	1903	because you never know, you know?).
1883		1904
1884	As another example, the Perl Coro module uses these hooks to integrate	1905	As another example, the Perl Coro module uses these hooks to integrate
…		…
1927	and in a check watcher, destroy them and call into libadns. What follows	1948	and in a check watcher, destroy them and call into libadns. What follows
1928	is pseudo-code only of course. This requires you to either use a low	1949	is pseudo-code only of course. This requires you to either use a low
1929	priority for the check watcher or use C<ev_clear_pending> explicitly, as	1950	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1930	the callbacks for the IO/timeout watchers might not have been called yet.	1951	the callbacks for the IO/timeout watchers might not have been called yet.
1931		1952
1932	static ev_io iow [nfd];	1953	static ev_io iow [nfd];
1933	static ev_timer tw;	1954	static ev_timer tw;
1934		1955
1935	static void	1956	static void
1936	io_cb (ev_loop *loop, ev_io *w, int revents)	1957	io_cb (ev_loop *loop, ev_io *w, int revents)
1937	{	1958	{
1938	}	1959	}
1939		1960
1940	// create io watchers for each fd and a timer before blocking	1961	// create io watchers for each fd and a timer before blocking
1941	static void	1962	static void
1942	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1963	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1943	{	1964	{
1944	int timeout = 3600000;	1965	int timeout = 3600000;
1945	struct pollfd fds [nfd];	1966	struct pollfd fds [nfd];
1946	// actual code will need to loop here and realloc etc.	1967	// actual code will need to loop here and realloc etc.
1947	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1968	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1948		1969
1949	/* the callback is illegal, but won't be called as we stop during check */	1970	/* the callback is illegal, but won't be called as we stop during check */
1950	ev_timer_init (&tw, 0, timeout * 1e-3);	1971	ev_timer_init (&tw, 0, timeout * 1e-3);
1951	ev_timer_start (loop, &tw);	1972	ev_timer_start (loop, &tw);
1952		1973
1953	// create one ev_io per pollfd	1974	// create one ev_io per pollfd
1954	for (int i = 0; i < nfd; ++i)	1975	for (int i = 0; i < nfd; ++i)
1955	{	1976	{
1956	ev_io_init (iow + i, io_cb, fds [i].fd,	1977	ev_io_init (iow + i, io_cb, fds [i].fd,
1957	((fds [i].events & POLLIN ? EV_READ : 0)	1978	((fds [i].events & POLLIN ? EV_READ : 0)
1958	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1979	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1959		1980
1960	fds [i].revents = 0;	1981	fds [i].revents = 0;
1961	ev_io_start (loop, iow + i);	1982	ev_io_start (loop, iow + i);
1962	}	1983	}
1963	}	1984	}
1964		1985
1965	// stop all watchers after blocking	1986	// stop all watchers after blocking
1966	static void	1987	static void
1967	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1988	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1968	{	1989	{
1969	ev_timer_stop (loop, &tw);	1990	ev_timer_stop (loop, &tw);
1970		1991
1971	for (int i = 0; i < nfd; ++i)	1992	for (int i = 0; i < nfd; ++i)
1972	{	1993	{
1973	// set the relevant poll flags	1994	// set the relevant poll flags
1974	// could also call adns_processreadable etc. here	1995	// could also call adns_processreadable etc. here
1975	struct pollfd *fd = fds + i;	1996	struct pollfd *fd = fds + i;
1976	int revents = ev_clear_pending (iow + i);	1997	int revents = ev_clear_pending (iow + i);
1977	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	1998	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1978	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	1999	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1979		2000
1980	// now stop the watcher	2001	// now stop the watcher
1981	ev_io_stop (loop, iow + i);	2002	ev_io_stop (loop, iow + i);
1982	}	2003	}
1983		2004
1984	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2005	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1985	}	2006	}
1986		2007
1987	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2008	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
1988	in the prepare watcher and would dispose of the check watcher.	2009	in the prepare watcher and would dispose of the check watcher.
1989		2010
1990	Method 3: If the module to be embedded supports explicit event	2011	Method 3: If the module to be embedded supports explicit event
1991	notification (adns does), you can also make use of the actual watcher	2012	notification (libadns does), you can also make use of the actual watcher
1992	callbacks, and only destroy/create the watchers in the prepare watcher.	2013	callbacks, and only destroy/create the watchers in the prepare watcher.
1993		2014
1994	static void	2015	static void
1995	timer_cb (EV_P_ ev_timer *w, int revents)	2016	timer_cb (EV_P_ ev_timer *w, int revents)
1996	{	2017	{
1997	adns_state ads = (adns_state)w->data;	2018	adns_state ads = (adns_state)w->data;
1998	update_now (EV_A);	2019	update_now (EV_A);
1999		2020
2000	adns_processtimeouts (ads, &tv_now);	2021	adns_processtimeouts (ads, &tv_now);
2001	}	2022	}
2002		2023
2003	static void	2024	static void
2004	io_cb (EV_P_ ev_io *w, int revents)	2025	io_cb (EV_P_ ev_io *w, int revents)
2005	{	2026	{
2006	adns_state ads = (adns_state)w->data;	2027	adns_state ads = (adns_state)w->data;
2007	update_now (EV_A);	2028	update_now (EV_A);
2008		2029
2009	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2030	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
2010	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2031	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
2011	}	2032	}
2012		2033
2013	// do not ever call adns_afterpoll	2034	// do not ever call adns_afterpoll
2014		2035
2015	Method 4: Do not use a prepare or check watcher because the module you	2036	Method 4: Do not use a prepare or check watcher because the module you
2016	want to embed is too inflexible to support it. Instead, youc na override	2037	want to embed is too inflexible to support it. Instead, you can override
2017	their poll function. The drawback with this solution is that the main	2038	their poll function. The drawback with this solution is that the main
2018	loop is now no longer controllable by EV. The C<Glib::EV> module does	2039	loop is now no longer controllable by EV. The C<Glib::EV> module does
2019	this.	2040	this.
2020		2041
2021	static gint	2042	static gint
2022	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2043	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
2023	{	2044	{
2024	int got_events = 0;	2045	int got_events = 0;
2025		2046
2026	for (n = 0; n < nfds; ++n)	2047	for (n = 0; n < nfds; ++n)
2027	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2048	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
2028		2049
2029	if (timeout >= 0)	2050	if (timeout >= 0)
2030	// create/start timer	2051	// create/start timer
2031		2052
2032	// poll	2053	// poll
2033	ev_loop (EV_A_ 0);	2054	ev_loop (EV_A_ 0);
2034		2055
2035	// stop timer again	2056	// stop timer again
2036	if (timeout >= 0)	2057	if (timeout >= 0)
2037	ev_timer_stop (EV_A_ &to);	2058	ev_timer_stop (EV_A_ &to);
2038		2059
2039	// stop io watchers again - their callbacks should have set	2060	// stop io watchers again - their callbacks should have set
2040	for (n = 0; n < nfds; ++n)	2061	for (n = 0; n < nfds; ++n)
2041	ev_io_stop (EV_A_ iow [n]);	2062	ev_io_stop (EV_A_ iow [n]);
2042		2063
2043	return got_events;	2064	return got_events;
2044	}	2065	}
2045		2066
2046		2067
2047	=head2 C<ev_embed> - when one backend isn't enough...	2068	=head2 C<ev_embed> - when one backend isn't enough...
2048		2069
2049	This is a rather advanced watcher type that lets you embed one event loop	2070	This is a rather advanced watcher type that lets you embed one event loop
…		…
2105		2126
2106	Configures the watcher to embed the given loop, which must be	2127	Configures the watcher to embed the given loop, which must be
2107	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be	2128	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
2108	invoked automatically, otherwise it is the responsibility of the callback	2129	invoked automatically, otherwise it is the responsibility of the callback
2109	to invoke it (it will continue to be called until the sweep has been done,	2130	to invoke it (it will continue to be called until the sweep has been done,
2110	if you do not want thta, you need to temporarily stop the embed watcher).	2131	if you do not want that, you need to temporarily stop the embed watcher).
2111		2132
2112	=item ev_embed_sweep (loop, ev_embed *)	2133	=item ev_embed_sweep (loop, ev_embed *)
2113		2134
2114	Make a single, non-blocking sweep over the embedded loop. This works	2135	Make a single, non-blocking sweep over the embedded loop. This works
2115	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2136	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2116	apropriate way for embedded loops.	2137	appropriate way for embedded loops.
2117		2138
2118	=item struct ev_loop *other [read-only]	2139	=item struct ev_loop *other [read-only]
2119		2140
2120	The embedded event loop.	2141	The embedded event loop.
2121		2142
…		…
2123		2144
2124	=head3 Examples	2145	=head3 Examples
2125		2146
2126	Example: Try to get an embeddable event loop and embed it into the default	2147	Example: Try to get an embeddable event loop and embed it into the default
2127	event loop. If that is not possible, use the default loop. The default	2148	event loop. If that is not possible, use the default loop. The default
2128	loop is stored in C<loop_hi>, while the mebeddable loop is stored in	2149	loop is stored in C<loop_hi>, while the embeddable loop is stored in
2129	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be	2150	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2130	used).	2151	used).
2131		2152
2132	struct ev_loop *loop_hi = ev_default_init (0);	2153	struct ev_loop *loop_hi = ev_default_init (0);
2133	struct ev_loop *loop_lo = 0;	2154	struct ev_loop *loop_lo = 0;
2134	struct ev_embed embed;	2155	struct ev_embed embed;
2135		2156
2136	// see if there is a chance of getting one that works	2157	// see if there is a chance of getting one that works
2137	// (remember that a flags value of 0 means autodetection)	2158	// (remember that a flags value of 0 means autodetection)
2138	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2159	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2139	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2160	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2140	: 0;	2161	: 0;
2141		2162
2142	// if we got one, then embed it, otherwise default to loop_hi	2163	// if we got one, then embed it, otherwise default to loop_hi
2143	if (loop_lo)	2164	if (loop_lo)
2144	{	2165	{
2145	ev_embed_init (&embed, 0, loop_lo);	2166	ev_embed_init (&embed, 0, loop_lo);
2146	ev_embed_start (loop_hi, &embed);	2167	ev_embed_start (loop_hi, &embed);
2147	}	2168	}
2148	else	2169	else
2149	loop_lo = loop_hi;	2170	loop_lo = loop_hi;
2150		2171
2151	Example: Check if kqueue is available but not recommended and create	2172	Example: Check if kqueue is available but not recommended and create
2152	a kqueue backend for use with sockets (which usually work with any	2173	a kqueue backend for use with sockets (which usually work with any
2153	kqueue implementation). Store the kqueue/socket-only event loop in	2174	kqueue implementation). Store the kqueue/socket-only event loop in
2154	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2175	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2155		2176
2156	struct ev_loop *loop = ev_default_init (0);	2177	struct ev_loop *loop = ev_default_init (0);
2157	struct ev_loop *loop_socket = 0;	2178	struct ev_loop *loop_socket = 0;
2158	struct ev_embed embed;	2179	struct ev_embed embed;
2159		2180
2160	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2181	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2161	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2182	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2162	{	2183	{
2163	ev_embed_init (&embed, 0, loop_socket);	2184	ev_embed_init (&embed, 0, loop_socket);
2164	ev_embed_start (loop, &embed);	2185	ev_embed_start (loop, &embed);
2165	}	2186	}
2166		2187
2167	if (!loop_socket)	2188	if (!loop_socket)
2168	loop_socket = loop;	2189	loop_socket = loop;
2169		2190
2170	// now use loop_socket for all sockets, and loop for everything else	2191	// now use loop_socket for all sockets, and loop for everything else
2171		2192
2172		2193
2173	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2194	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2174		2195
2175	Fork watchers are called when a C<fork ()> was detected (usually because	2196	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2228		2249
2229	=item queueing from a signal handler context	2250	=item queueing from a signal handler context
2230		2251
2231	To implement race-free queueing, you simply add to the queue in the signal	2252	To implement race-free queueing, you simply add to the queue in the signal
2232	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2253	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2233	some fictitiuous SIGUSR1 handler:	2254	some fictitious SIGUSR1 handler:
2234		2255
2235	static ev_async mysig;	2256	static ev_async mysig;
2236		2257
2237	static void	2258	static void
2238	sigusr1_handler (void)	2259	sigusr1_handler (void)
…		…
2312	=item ev_async_send (loop, ev_async *)	2333	=item ev_async_send (loop, ev_async *)
2313		2334
2314	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2335	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2315	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2336	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2316	C<ev_feed_event>, this call is safe to do in other threads, signal or	2337	C<ev_feed_event>, this call is safe to do in other threads, signal or
2317	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding	2338	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2318	section below on what exactly this means).	2339	section below on what exactly this means).
2319		2340
2320	This call incurs the overhead of a syscall only once per loop iteration,	2341	This call incurs the overhead of a system call only once per loop iteration,
2321	so while the overhead might be noticable, it doesn't apply to repeated	2342	so while the overhead might be noticeable, it doesn't apply to repeated
2322	calls to C<ev_async_send>.	2343	calls to C<ev_async_send>.
2323		2344
2324	=item bool = ev_async_pending (ev_async *)	2345	=item bool = ev_async_pending (ev_async *)
2325		2346
2326	Returns a non-zero value when C<ev_async_send> has been called on the	2347	Returns a non-zero value when C<ev_async_send> has been called on the
…		…
2328	event loop.	2349	event loop.
2329		2350
2330	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When	2351	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
2331	the loop iterates next and checks for the watcher to have become active,	2352	the loop iterates next and checks for the watcher to have become active,
2332	it will reset the flag again. C<ev_async_pending> can be used to very	2353	it will reset the flag again. C<ev_async_pending> can be used to very
2333	quickly check wether invoking the loop might be a good idea.	2354	quickly check whether invoking the loop might be a good idea.
2334		2355
2335	Not that this does I<not> check wether the watcher itself is pending, only	2356	Not that this does I<not> check whether the watcher itself is pending, only
2336	wether it has been requested to make this watcher pending.	2357	whether it has been requested to make this watcher pending.
2337		2358
2338	=back	2359	=back
2339		2360
2340		2361
2341	=head1 OTHER FUNCTIONS	2362	=head1 OTHER FUNCTIONS
…		…
2352	or timeout without having to allocate/configure/start/stop/free one or	2373	or timeout without having to allocate/configure/start/stop/free one or
2353	more watchers yourself.	2374	more watchers yourself.
2354		2375
2355	If C<fd> is less than 0, then no I/O watcher will be started and events	2376	If C<fd> is less than 0, then no I/O watcher will be started and events
2356	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2377	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2357	C<events> set will be craeted and started.	2378	C<events> set will be created and started.
2358		2379
2359	If C<timeout> is less than 0, then no timeout watcher will be	2380	If C<timeout> is less than 0, then no timeout watcher will be
2360	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2381	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2361	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2382	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2362	dubious value.	2383	dubious value.
…		…
2364	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2385	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2365	passed an C<revents> set like normal event callbacks (a combination of	2386	passed an C<revents> set like normal event callbacks (a combination of
2366	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2387	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2367	value passed to C<ev_once>:	2388	value passed to C<ev_once>:
2368		2389
2369	static void stdin_ready (int revents, void *arg)	2390	static void stdin_ready (int revents, void *arg)
2370	{	2391	{
2371	if (revents & EV_TIMEOUT)	2392	if (revents & EV_TIMEOUT)
2372	/* doh, nothing entered */;	2393	/* doh, nothing entered */;
2373	else if (revents & EV_READ)	2394	else if (revents & EV_READ)
2374	/* stdin might have data for us, joy! */;	2395	/* stdin might have data for us, joy! */;
2375	}	2396	}
2376		2397
2377	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2398	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2378		2399
2379	=item ev_feed_event (ev_loop *, watcher *, int revents)	2400	=item ev_feed_event (ev_loop *, watcher *, int revents)
2380		2401
2381	Feeds the given event set into the event loop, as if the specified event	2402	Feeds the given event set into the event loop, as if the specified event
2382	had happened for the specified watcher (which must be a pointer to an	2403	had happened for the specified watcher (which must be a pointer to an
…		…
2387	Feed an event on the given fd, as if a file descriptor backend detected	2408	Feed an event on the given fd, as if a file descriptor backend detected
2388	the given events it.	2409	the given events it.
2389		2410
2390	=item ev_feed_signal_event (ev_loop *loop, int signum)	2411	=item ev_feed_signal_event (ev_loop *loop, int signum)
2391		2412
2392	Feed an event as if the given signal occured (C<loop> must be the default	2413	Feed an event as if the given signal occurred (C<loop> must be the default
2393	loop!).	2414	loop!).
2394		2415
2395	=back	2416	=back
2396		2417
2397		2418
…		…
2426	=back	2447	=back
2427		2448
2428	=head1 C++ SUPPORT	2449	=head1 C++ SUPPORT
2429		2450
2430	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2451	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2431	you to use some convinience methods to start/stop watchers and also change	2452	you to use some convenience methods to start/stop watchers and also change
2432	the callback model to a model using method callbacks on objects.	2453	the callback model to a model using method callbacks on objects.
2433		2454
2434	To use it,	2455	To use it,
2435		2456
2436	#include <ev++.h>	2457	#include <ev++.h>
2437		2458
2438	This automatically includes F<ev.h> and puts all of its definitions (many	2459	This automatically includes F<ev.h> and puts all of its definitions (many
2439	of them macros) into the global namespace. All C++ specific things are	2460	of them macros) into the global namespace. All C++ specific things are
2440	put into the C<ev> namespace. It should support all the same embedding	2461	put into the C<ev> namespace. It should support all the same embedding
2441	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2462	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2508	your compiler is good :), then the method will be fully inlined into the	2529	your compiler is good :), then the method will be fully inlined into the
2509	thunking function, making it as fast as a direct C callback.	2530	thunking function, making it as fast as a direct C callback.
2510		2531
2511	Example: simple class declaration and watcher initialisation	2532	Example: simple class declaration and watcher initialisation
2512		2533
2513	struct myclass	2534	struct myclass
2514	{	2535	{
2515	void io_cb (ev::io &w, int revents) { }	2536	void io_cb (ev::io &w, int revents) { }
2516	}	2537	}
2517		2538
2518	myclass obj;	2539	myclass obj;
2519	ev::io iow;	2540	ev::io iow;
2520	iow.set <myclass, &myclass::io_cb> (&obj);	2541	iow.set <myclass, &myclass::io_cb> (&obj);
2521		2542
2522	=item w->set<function> (void *data = 0)	2543	=item w->set<function> (void *data = 0)
2523		2544
2524	Also sets a callback, but uses a static method or plain function as	2545	Also sets a callback, but uses a static method or plain function as
2525	callback. The optional C<data> argument will be stored in the watcher's	2546	callback. The optional C<data> argument will be stored in the watcher's
…		…
2529		2550
2530	See the method-C<set> above for more details.	2551	See the method-C<set> above for more details.
2531		2552
2532	Example:	2553	Example:
2533		2554
2534	static void io_cb (ev::io &w, int revents) { }	2555	static void io_cb (ev::io &w, int revents) { }
2535	iow.set <io_cb> ();	2556	iow.set <io_cb> ();
2536		2557
2537	=item w->set (struct ev_loop *)	2558	=item w->set (struct ev_loop *)
2538		2559
2539	Associates a different C<struct ev_loop> with this watcher. You can only	2560	Associates a different C<struct ev_loop> with this watcher. You can only
2540	do this when the watcher is inactive (and not pending either).	2561	do this when the watcher is inactive (and not pending either).
2541		2562
2542	=item w->set ([args])	2563	=item w->set ([arguments])
2543		2564
2544	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2565	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2545	called at least once. Unlike the C counterpart, an active watcher gets	2566	called at least once. Unlike the C counterpart, an active watcher gets
2546	automatically stopped and restarted when reconfiguring it with this	2567	automatically stopped and restarted when reconfiguring it with this
2547	method.	2568	method.
2548		2569
2549	=item w->start ()	2570	=item w->start ()
…		…
2573	=back	2594	=back
2574		2595
2575	Example: Define a class with an IO and idle watcher, start one of them in	2596	Example: Define a class with an IO and idle watcher, start one of them in
2576	the constructor.	2597	the constructor.
2577		2598
2578	class myclass	2599	class myclass
2579	{	2600	{
2580	ev::io io; void io_cb (ev::io &w, int revents);	2601	ev::io io; void io_cb (ev::io &w, int revents);
2581	ev:idle idle void idle_cb (ev::idle &w, int revents);	2602	ev:idle idle void idle_cb (ev::idle &w, int revents);
2582		2603
2583	myclass (int fd)	2604	myclass (int fd)
2584	{	2605	{
2585	io .set <myclass, &myclass::io_cb > (this);	2606	io .set <myclass, &myclass::io_cb > (this);
2586	idle.set <myclass, &myclass::idle_cb> (this);	2607	idle.set <myclass, &myclass::idle_cb> (this);
2587		2608
2588	io.start (fd, ev::READ);	2609	io.start (fd, ev::READ);
2589	}	2610	}
2590	};	2611	};
2591		2612
2592		2613
2593	=head1 OTHER LANGUAGE BINDINGS	2614	=head1 OTHER LANGUAGE BINDINGS
2594		2615
2595	Libev does not offer other language bindings itself, but bindings for a	2616	Libev does not offer other language bindings itself, but bindings for a
2596	numbe rof languages exist in the form of third-party packages. If you know	2617	number of languages exist in the form of third-party packages. If you know
2597	any interesting language binding in addition to the ones listed here, drop	2618	any interesting language binding in addition to the ones listed here, drop
2598	me a note.	2619	me a note.
2599		2620
2600	=over 4	2621	=over 4
2601		2622
…		…
2605	libev. EV is developed together with libev. Apart from the EV core module,	2626	libev. EV is developed together with libev. Apart from the EV core module,
2606	there are additional modules that implement libev-compatible interfaces	2627	there are additional modules that implement libev-compatible interfaces
2607	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the	2628	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
2608	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).	2629	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2609		2630
2610	It can be found and installed via CPAN, its homepage is found at	2631	It can be found and installed via CPAN, its homepage is at
2611	L<http://software.schmorp.de/pkg/EV>.	2632	L<http://software.schmorp.de/pkg/EV>.
2612		2633
		2634	=item Python
		2635
		2636	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2637	seems to be quite complete and well-documented. Note, however, that the
		2638	patch they require for libev is outright dangerous as it breaks the ABI
		2639	for everybody else, and therefore, should never be applied in an installed
		2640	libev (if python requires an incompatible ABI then it needs to embed
		2641	libev).
		2642
2613	=item Ruby	2643	=item Ruby
2614		2644
2615	Tony Arcieri has written a ruby extension that offers access to a subset	2645	Tony Arcieri has written a ruby extension that offers access to a subset
2616	of the libev API and adds filehandle abstractions, asynchronous DNS and	2646	of the libev API and adds file handle abstractions, asynchronous DNS and
2617	more on top of it. It can be found via gem servers. Its homepage is at	2647	more on top of it. It can be found via gem servers. Its homepage is at
2618	L<http://rev.rubyforge.org/>.	2648	L<http://rev.rubyforge.org/>.
2619		2649
2620	=item D	2650	=item D
2621		2651
…		…
2625	=back	2655	=back
2626		2656
2627		2657
2628	=head1 MACRO MAGIC	2658	=head1 MACRO MAGIC
2629		2659
2630	Libev can be compiled with a variety of options, the most fundamantal	2660	Libev can be compiled with a variety of options, the most fundamental
2631	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2661	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2632	functions and callbacks have an initial C<struct ev_loop *> argument.	2662	functions and callbacks have an initial C<struct ev_loop *> argument.
2633		2663
2634	To make it easier to write programs that cope with either variant, the	2664	To make it easier to write programs that cope with either variant, the
2635	following macros are defined:	2665	following macros are defined:
…		…
2640		2670
2641	This provides the loop I<argument> for functions, if one is required ("ev	2671	This provides the loop I<argument> for functions, if one is required ("ev
2642	loop argument"). The C<EV_A> form is used when this is the sole argument,	2672	loop argument"). The C<EV_A> form is used when this is the sole argument,
2643	C<EV_A_> is used when other arguments are following. Example:	2673	C<EV_A_> is used when other arguments are following. Example:
2644		2674
2645	ev_unref (EV_A);	2675	ev_unref (EV_A);
2646	ev_timer_add (EV_A_ watcher);	2676	ev_timer_add (EV_A_ watcher);
2647	ev_loop (EV_A_ 0);	2677	ev_loop (EV_A_ 0);
2648		2678
2649	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2679	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2650	which is often provided by the following macro.	2680	which is often provided by the following macro.
2651		2681
2652	=item C<EV_P>, C<EV_P_>	2682	=item C<EV_P>, C<EV_P_>
2653		2683
2654	This provides the loop I<parameter> for functions, if one is required ("ev	2684	This provides the loop I<parameter> for functions, if one is required ("ev
2655	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2685	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2656	C<EV_P_> is used when other parameters are following. Example:	2686	C<EV_P_> is used when other parameters are following. Example:
2657		2687
2658	// this is how ev_unref is being declared	2688	// this is how ev_unref is being declared
2659	static void ev_unref (EV_P);	2689	static void ev_unref (EV_P);
2660		2690
2661	// this is how you can declare your typical callback	2691	// this is how you can declare your typical callback
2662	static void cb (EV_P_ ev_timer *w, int revents)	2692	static void cb (EV_P_ ev_timer *w, int revents)
2663		2693
2664	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2694	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2665	suitable for use with C<EV_A>.	2695	suitable for use with C<EV_A>.
2666		2696
2667	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2697	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
…		…
2683		2713
2684	Example: Declare and initialise a check watcher, utilising the above	2714	Example: Declare and initialise a check watcher, utilising the above
2685	macros so it will work regardless of whether multiple loops are supported	2715	macros so it will work regardless of whether multiple loops are supported
2686	or not.	2716	or not.
2687		2717
2688	static void	2718	static void
2689	check_cb (EV_P_ ev_timer *w, int revents)	2719	check_cb (EV_P_ ev_timer *w, int revents)
2690	{	2720	{
2691	ev_check_stop (EV_A_ w);	2721	ev_check_stop (EV_A_ w);
2692	}	2722	}
2693		2723
2694	ev_check check;	2724	ev_check check;
2695	ev_check_init (&check, check_cb);	2725	ev_check_init (&check, check_cb);
2696	ev_check_start (EV_DEFAULT_ &check);	2726	ev_check_start (EV_DEFAULT_ &check);
2697	ev_loop (EV_DEFAULT_ 0);	2727	ev_loop (EV_DEFAULT_ 0);
2698		2728
2699	=head1 EMBEDDING	2729	=head1 EMBEDDING
2700		2730
2701	Libev can (and often is) directly embedded into host	2731	Libev can (and often is) directly embedded into host
2702	applications. Examples of applications that embed it include the Deliantra	2732	applications. Examples of applications that embed it include the Deliantra
…		…
2709	libev somewhere in your source tree).	2739	libev somewhere in your source tree).
2710		2740
2711	=head2 FILESETS	2741	=head2 FILESETS
2712		2742
2713	Depending on what features you need you need to include one or more sets of files	2743	Depending on what features you need you need to include one or more sets of files
2714	in your app.	2744	in your application.
2715		2745
2716	=head3 CORE EVENT LOOP	2746	=head3 CORE EVENT LOOP
2717		2747
2718	To include only the libev core (all the C<ev_*> functions), with manual	2748	To include only the libev core (all the C<ev_*> functions), with manual
2719	configuration (no autoconf):	2749	configuration (no autoconf):
2720		2750
2721	#define EV_STANDALONE 1	2751	#define EV_STANDALONE 1
2722	#include "ev.c"	2752	#include "ev.c"
2723		2753
2724	This will automatically include F<ev.h>, too, and should be done in a	2754	This will automatically include F<ev.h>, too, and should be done in a
2725	single C source file only to provide the function implementations. To use	2755	single C source file only to provide the function implementations. To use
2726	it, do the same for F<ev.h> in all files wishing to use this API (best	2756	it, do the same for F<ev.h> in all files wishing to use this API (best
2727	done by writing a wrapper around F<ev.h> that you can include instead and	2757	done by writing a wrapper around F<ev.h> that you can include instead and
2728	where you can put other configuration options):	2758	where you can put other configuration options):
2729		2759
2730	#define EV_STANDALONE 1	2760	#define EV_STANDALONE 1
2731	#include "ev.h"	2761	#include "ev.h"
2732		2762
2733	Both header files and implementation files can be compiled with a C++	2763	Both header files and implementation files can be compiled with a C++
2734	compiler (at least, thats a stated goal, and breakage will be treated	2764	compiler (at least, thats a stated goal, and breakage will be treated
2735	as a bug).	2765	as a bug).
2736		2766
2737	You need the following files in your source tree, or in a directory	2767	You need the following files in your source tree, or in a directory
2738	in your include path (e.g. in libev/ when using -Ilibev):	2768	in your include path (e.g. in libev/ when using -Ilibev):
2739		2769
2740	ev.h	2770	ev.h
2741	ev.c	2771	ev.c
2742	ev_vars.h	2772	ev_vars.h
2743	ev_wrap.h	2773	ev_wrap.h
2744		2774
2745	ev_win32.c required on win32 platforms only	2775	ev_win32.c required on win32 platforms only
2746		2776
2747	ev_select.c only when select backend is enabled (which is enabled by default)	2777	ev_select.c only when select backend is enabled (which is enabled by default)
2748	ev_poll.c only when poll backend is enabled (disabled by default)	2778	ev_poll.c only when poll backend is enabled (disabled by default)
2749	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2779	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2750	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2780	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2751	ev_port.c only when the solaris port backend is enabled (disabled by default)	2781	ev_port.c only when the solaris port backend is enabled (disabled by default)
2752		2782
2753	F<ev.c> includes the backend files directly when enabled, so you only need	2783	F<ev.c> includes the backend files directly when enabled, so you only need
2754	to compile this single file.	2784	to compile this single file.
2755		2785
2756	=head3 LIBEVENT COMPATIBILITY API	2786	=head3 LIBEVENT COMPATIBILITY API
2757		2787
2758	To include the libevent compatibility API, also include:	2788	To include the libevent compatibility API, also include:
2759		2789
2760	#include "event.c"	2790	#include "event.c"
2761		2791
2762	in the file including F<ev.c>, and:	2792	in the file including F<ev.c>, and:
2763		2793
2764	#include "event.h"	2794	#include "event.h"
2765		2795
2766	in the files that want to use the libevent API. This also includes F<ev.h>.	2796	in the files that want to use the libevent API. This also includes F<ev.h>.
2767		2797
2768	You need the following additional files for this:	2798	You need the following additional files for this:
2769		2799
2770	event.h	2800	event.h
2771	event.c	2801	event.c
2772		2802
2773	=head3 AUTOCONF SUPPORT	2803	=head3 AUTOCONF SUPPORT
2774		2804
2775	Instead of using C<EV_STANDALONE=1> and providing your config in	2805	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2776	whatever way you want, you can also C<m4_include([libev.m4])> in your	2806	whatever way you want, you can also C<m4_include([libev.m4])> in your
2777	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2807	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2778	include F<config.h> and configure itself accordingly.	2808	include F<config.h> and configure itself accordingly.
2779		2809
2780	For this of course you need the m4 file:	2810	For this of course you need the m4 file:
2781		2811
2782	libev.m4	2812	libev.m4
2783		2813
2784	=head2 PREPROCESSOR SYMBOLS/MACROS	2814	=head2 PREPROCESSOR SYMBOLS/MACROS
2785		2815
2786	Libev can be configured via a variety of preprocessor symbols you have to	2816	Libev can be configured via a variety of preprocessor symbols you have to
2787	define before including any of its files. The default in the absense of	2817	define before including any of its files. The default in the absence of
2788	autoconf is noted for every option.	2818	autoconf is noted for every option.
2789		2819
2790	=over 4	2820	=over 4
2791		2821
2792	=item EV_STANDALONE	2822	=item EV_STANDALONE
…		…
2798	F<event.h> that are not directly supported by the libev core alone.	2828	F<event.h> that are not directly supported by the libev core alone.
2799		2829
2800	=item EV_USE_MONOTONIC	2830	=item EV_USE_MONOTONIC
2801		2831
2802	If defined to be C<1>, libev will try to detect the availability of the	2832	If defined to be C<1>, libev will try to detect the availability of the
2803	monotonic clock option at both compiletime and runtime. Otherwise no use	2833	monotonic clock option at both compile time and runtime. Otherwise no use
2804	of the monotonic clock option will be attempted. If you enable this, you	2834	of the monotonic clock option will be attempted. If you enable this, you
2805	usually have to link against librt or something similar. Enabling it when	2835	usually have to link against librt or something similar. Enabling it when
2806	the functionality isn't available is safe, though, although you have	2836	the functionality isn't available is safe, though, although you have
2807	to make sure you link against any libraries where the C<clock_gettime>	2837	to make sure you link against any libraries where the C<clock_gettime>
2808	function is hiding in (often F<-lrt>).	2838	function is hiding in (often F<-lrt>).
2809		2839
2810	=item EV_USE_REALTIME	2840	=item EV_USE_REALTIME
2811		2841
2812	If defined to be C<1>, libev will try to detect the availability of the	2842	If defined to be C<1>, libev will try to detect the availability of the
2813	realtime clock option at compiletime (and assume its availability at	2843	real-time clock option at compile time (and assume its availability at
2814	runtime if successful). Otherwise no use of the realtime clock option will	2844	runtime if successful). Otherwise no use of the real-time clock option will
2815	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2845	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2816	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2846	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2817	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2847	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2818		2848
2819	=item EV_USE_NANOSLEEP	2849	=item EV_USE_NANOSLEEP
…		…
2830	2.7 or newer, otherwise disabled.	2860	2.7 or newer, otherwise disabled.
2831		2861
2832	=item EV_USE_SELECT	2862	=item EV_USE_SELECT
2833		2863
2834	If undefined or defined to be C<1>, libev will compile in support for the	2864	If undefined or defined to be C<1>, libev will compile in support for the
2835	C<select>(2) backend. No attempt at autodetection will be done: if no	2865	C<select>(2) backend. No attempt at auto-detection will be done: if no
2836	other method takes over, select will be it. Otherwise the select backend	2866	other method takes over, select will be it. Otherwise the select backend
2837	will not be compiled in.	2867	will not be compiled in.
2838		2868
2839	=item EV_SELECT_USE_FD_SET	2869	=item EV_SELECT_USE_FD_SET
2840		2870
2841	If defined to C<1>, then the select backend will use the system C<fd_set>	2871	If defined to C<1>, then the select backend will use the system C<fd_set>
2842	structure. This is useful if libev doesn't compile due to a missing	2872	structure. This is useful if libev doesn't compile due to a missing
2843	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	2873	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
2844	exotic systems. This usually limits the range of file descriptors to some	2874	exotic systems. This usually limits the range of file descriptors to some
2845	low limit such as 1024 or might have other limitations (winsocket only	2875	low limit such as 1024 or might have other limitations (winsocket only
2846	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	2876	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2847	influence the size of the C<fd_set> used.	2877	influence the size of the C<fd_set> used.
2848		2878
…		…
2897	otherwise another method will be used as fallback. This is the preferred	2927	otherwise another method will be used as fallback. This is the preferred
2898	backend for Solaris 10 systems.	2928	backend for Solaris 10 systems.
2899		2929
2900	=item EV_USE_DEVPOLL	2930	=item EV_USE_DEVPOLL
2901		2931
2902	reserved for future expansion, works like the USE symbols above.	2932	Reserved for future expansion, works like the USE symbols above.
2903		2933
2904	=item EV_USE_INOTIFY	2934	=item EV_USE_INOTIFY
2905		2935
2906	If defined to be C<1>, libev will compile in support for the Linux inotify	2936	If defined to be C<1>, libev will compile in support for the Linux inotify
2907	interface to speed up C<ev_stat> watchers. Its actual availability will	2937	interface to speed up C<ev_stat> watchers. Its actual availability will
…		…
2914	access is atomic with respect to other threads or signal contexts. No such	2944	access is atomic with respect to other threads or signal contexts. No such
2915	type is easily found in the C language, so you can provide your own type	2945	type is easily found in the C language, so you can provide your own type
2916	that you know is safe for your purposes. It is used both for signal handler "locking"	2946	that you know is safe for your purposes. It is used both for signal handler "locking"
2917	as well as for signal and thread safety in C<ev_async> watchers.	2947	as well as for signal and thread safety in C<ev_async> watchers.
2918		2948
2919	In the absense of this define, libev will use C<sig_atomic_t volatile>	2949	In the absence of this define, libev will use C<sig_atomic_t volatile>
2920	(from F<signal.h>), which is usually good enough on most platforms.	2950	(from F<signal.h>), which is usually good enough on most platforms.
2921		2951
2922	=item EV_H	2952	=item EV_H
2923		2953
2924	The name of the F<ev.h> header file used to include it. The default if	2954	The name of the F<ev.h> header file used to include it. The default if
…		…
2963	When doing priority-based operations, libev usually has to linearly search	2993	When doing priority-based operations, libev usually has to linearly search
2964	all the priorities, so having many of them (hundreds) uses a lot of space	2994	all the priorities, so having many of them (hundreds) uses a lot of space
2965	and time, so using the defaults of five priorities (-2 .. +2) is usually	2995	and time, so using the defaults of five priorities (-2 .. +2) is usually
2966	fine.	2996	fine.
2967		2997
2968	If your embedding app does not need any priorities, defining these both to	2998	If your embedding application does not need any priorities, defining these both to
2969	C<0> will save some memory and cpu.	2999	C<0> will save some memory and CPU.
2970		3000
2971	=item EV_PERIODIC_ENABLE	3001	=item EV_PERIODIC_ENABLE
2972		3002
2973	If undefined or defined to be C<1>, then periodic timers are supported. If	3003	If undefined or defined to be C<1>, then periodic timers are supported. If
2974	defined to be C<0>, then they are not. Disabling them saves a few kB of	3004	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
3002		3032
3003	=item EV_MINIMAL	3033	=item EV_MINIMAL
3004		3034
3005	If you need to shave off some kilobytes of code at the expense of some	3035	If you need to shave off some kilobytes of code at the expense of some
3006	speed, define this symbol to C<1>. Currently this is used to override some	3036	speed, define this symbol to C<1>. Currently this is used to override some
3007	inlining decisions, saves roughly 30% codesize of amd64. It also selects a	3037	inlining decisions, saves roughly 30% code size on amd64. It also selects a
3008	much smaller 2-heap for timer management over the default 4-heap.	3038	much smaller 2-heap for timer management over the default 4-heap.
3009		3039
3010	=item EV_PID_HASHSIZE	3040	=item EV_PID_HASHSIZE
3011		3041
3012	C<ev_child> watchers use a small hash table to distribute workload by	3042	C<ev_child> watchers use a small hash table to distribute workload by
…		…
3025	=item EV_USE_4HEAP	3055	=item EV_USE_4HEAP
3026		3056
3027	Heaps are not very cache-efficient. To improve the cache-efficiency of the	3057	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3028	timer and periodics heap, libev uses a 4-heap when this symbol is defined	3058	timer and periodics heap, libev uses a 4-heap when this symbol is defined
3029	to C<1>. The 4-heap uses more complicated (longer) code but has	3059	to C<1>. The 4-heap uses more complicated (longer) code but has
3030	noticably faster performance with many (thousands) of watchers.	3060	noticeably faster performance with many (thousands) of watchers.
3031		3061
3032	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	3062	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
3033	(disabled).	3063	(disabled).
3034		3064
3035	=item EV_HEAP_CACHE_AT	3065	=item EV_HEAP_CACHE_AT
…		…
3037	Heaps are not very cache-efficient. To improve the cache-efficiency of the	3067	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3038	timer and periodics heap, libev can cache the timestamp (I<at>) within	3068	timer and periodics heap, libev can cache the timestamp (I<at>) within
3039	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	3069	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3040	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	3070	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3041	but avoids random read accesses on heap changes. This improves performance	3071	but avoids random read accesses on heap changes. This improves performance
3042	noticably with with many (hundreds) of watchers.	3072	noticeably with with many (hundreds) of watchers.
3043		3073
3044	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	3074	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
3045	(disabled).	3075	(disabled).
3046		3076
3047	=item EV_VERIFY	3077	=item EV_VERIFY
…		…
3064	members. You have to define it each time you include one of the files,	3094	members. You have to define it each time you include one of the files,
3065	though, and it must be identical each time.	3095	though, and it must be identical each time.
3066		3096
3067	For example, the perl EV module uses something like this:	3097	For example, the perl EV module uses something like this:
3068		3098
3069	#define EV_COMMON \	3099	#define EV_COMMON \
3070	SV *self; /* contains this struct */ \	3100	SV *self; /* contains this struct */ \
3071	SV *cb_sv, *fh /* note no trailing ";" */	3101	SV *cb_sv, *fh /* note no trailing ";" */
3072		3102
3073	=item EV_CB_DECLARE (type)	3103	=item EV_CB_DECLARE (type)
3074		3104
3075	=item EV_CB_INVOKE (watcher, revents)	3105	=item EV_CB_INVOKE (watcher, revents)
3076		3106
…		…
3083	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3113	avoid the C<struct ev_loop *> as first argument in all cases, or to use
3084	method calls instead of plain function calls in C++.	3114	method calls instead of plain function calls in C++.
3085		3115
3086	=head2 EXPORTED API SYMBOLS	3116	=head2 EXPORTED API SYMBOLS
3087		3117
3088	If you need to re-export the API (e.g. via a dll) and you need a list of	3118	If you need to re-export the API (e.g. via a DLL) and you need a list of
3089	exported symbols, you can use the provided F<Symbol.*> files which list	3119	exported symbols, you can use the provided F<Symbol.*> files which list
3090	all public symbols, one per line:	3120	all public symbols, one per line:
3091		3121
3092	Symbols.ev for libev proper	3122	Symbols.ev for libev proper
3093	Symbols.event for the libevent emulation	3123	Symbols.event for the libevent emulation
3094		3124
3095	This can also be used to rename all public symbols to avoid clashes with	3125	This can also be used to rename all public symbols to avoid clashes with
3096	multiple versions of libev linked together (which is obviously bad in	3126	multiple versions of libev linked together (which is obviously bad in
3097	itself, but sometimes it is inconvinient to avoid this).	3127	itself, but sometimes it is inconvenient to avoid this).
3098		3128
3099	A sed command like this will create wrapper C<#define>'s that you need to	3129	A sed command like this will create wrapper C<#define>'s that you need to
3100	include before including F<ev.h>:	3130	include before including F<ev.h>:
3101		3131
3102	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3132	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3119	file.	3149	file.
3120		3150
3121	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3151	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3122	that everybody includes and which overrides some configure choices:	3152	that everybody includes and which overrides some configure choices:
3123		3153
3124	#define EV_MINIMAL 1	3154	#define EV_MINIMAL 1
3125	#define EV_USE_POLL 0	3155	#define EV_USE_POLL 0
3126	#define EV_MULTIPLICITY 0	3156	#define EV_MULTIPLICITY 0
3127	#define EV_PERIODIC_ENABLE 0	3157	#define EV_PERIODIC_ENABLE 0
3128	#define EV_STAT_ENABLE 0	3158	#define EV_STAT_ENABLE 0
3129	#define EV_FORK_ENABLE 0	3159	#define EV_FORK_ENABLE 0
3130	#define EV_CONFIG_H <config.h>	3160	#define EV_CONFIG_H <config.h>
3131	#define EV_MINPRI 0	3161	#define EV_MINPRI 0
3132	#define EV_MAXPRI 0	3162	#define EV_MAXPRI 0
3133		3163
3134	#include "ev++.h"	3164	#include "ev++.h"
3135		3165
3136	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3166	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3137		3167
3138	#include "ev_cpp.h"	3168	#include "ev_cpp.h"
3139	#include "ev.c"	3169	#include "ev.c"
3140		3170
3141		3171
3142	=head1 THREADS AND COROUTINES	3172	=head1 THREADS AND COROUTINES
3143		3173
3144	=head2 THREADS	3174	=head2 THREADS
3145		3175
3146	Libev itself is completely threadsafe, but it uses no locking. This	3176	Libev itself is completely thread-safe, but it uses no locking. This
3147	means that you can use as many loops as you want in parallel, as long as	3177	means that you can use as many loops as you want in parallel, as long as
3148	only one thread ever calls into one libev function with the same loop	3178	only one thread ever calls into one libev function with the same loop
3149	parameter.	3179	parameter.
3150		3180
3151	Or put differently: calls with different loop parameters can be done in	3181	Or put differently: calls with different loop parameters can be done in
…		…
3158	help you but by giving some generic advice:	3188	help you but by giving some generic advice:
3159		3189
3160	=over 4	3190	=over 4
3161		3191
3162	=item * most applications have a main thread: use the default libev loop	3192	=item * most applications have a main thread: use the default libev loop
3163	in that thread, or create a seperate thread running only the default loop.	3193	in that thread, or create a separate thread running only the default loop.
3164		3194
3165	This helps integrating other libraries or software modules that use libev	3195	This helps integrating other libraries or software modules that use libev
3166	themselves and don't care/know about threading.	3196	themselves and don't care/know about threading.
3167		3197
3168	=item * one loop per thread is usually a good model.	3198	=item * one loop per thread is usually a good model.
3169		3199
3170	Doing this is almost never wrong, sometimes a better-performance model	3200	Doing this is almost never wrong, sometimes a better-performance model
3171	exists, but it is always a good start.	3201	exists, but it is always a good start.
3172		3202
3173	=item * other models exist, such as the leader/follower pattern, where one	3203	=item * other models exist, such as the leader/follower pattern, where one
3174	loop is handed through multiple threads in a kind of round-robbin fashion.	3204	loop is handed through multiple threads in a kind of round-robin fashion.
3175		3205
3176	Chosing a model is hard - look around, learn, know that usually you cna do	3206	Choosing a model is hard - look around, learn, know that usually you can do
3177	better than you currently do :-)	3207	better than you currently do :-)
3178		3208
3179	=item * often you need to talk to some other thread which blocks in the	3209	=item * often you need to talk to some other thread which blocks in the
3180	event loop - C<ev_async> watchers can be used to wake them up from other	3210	event loop - C<ev_async> watchers can be used to wake them up from other
3181	threads safely (or from signal contexts...).	3211	threads safely (or from signal contexts...).
3182		3212
3183	=back	3213	=back
3184		3214
3185	=head2 COROUTINES	3215	=head2 COROUTINES
3186		3216
3187	Libev is much more accomodating to coroutines ("cooperative threads"):	3217	Libev is much more accommodating to coroutines ("cooperative threads"):
3188	libev fully supports nesting calls to it's functions from different	3218	libev fully supports nesting calls to it's functions from different
3189	coroutines (e.g. you can call C<ev_loop> on the same loop from two	3219	coroutines (e.g. you can call C<ev_loop> on the same loop from two
3190	different coroutines and switch freely between both coroutines running the	3220	different coroutines and switch freely between both coroutines running the
3191	loop, as long as you don't confuse yourself). The only exception is that	3221	loop, as long as you don't confuse yourself). The only exception is that
3192	you must not do this from C<ev_periodic> reschedule callbacks.	3222	you must not do this from C<ev_periodic> reschedule callbacks.
…		…
3240		3270
3241	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3271	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3242		3272
3243	A change means an I/O watcher gets started or stopped, which requires	3273	A change means an I/O watcher gets started or stopped, which requires
3244	libev to recalculate its status (and possibly tell the kernel, depending	3274	libev to recalculate its status (and possibly tell the kernel, depending
3245	on backend and wether C<ev_io_set> was used).	3275	on backend and whether C<ev_io_set> was used).
3246		3276
3247	=item Activating one watcher (putting it into the pending state): O(1)	3277	=item Activating one watcher (putting it into the pending state): O(1)
3248		3278
3249	=item Priority handling: O(number_of_priorities)	3279	=item Priority handling: O(number_of_priorities)
3250		3280
…		…
3257		3287
3258	=item Processing ev_async_send: O(number_of_async_watchers)	3288	=item Processing ev_async_send: O(number_of_async_watchers)
3259		3289
3260	=item Processing signals: O(max_signal_number)	3290	=item Processing signals: O(max_signal_number)
3261		3291
3262	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3292	Sending involves a system call I<iff> there were no other C<ev_async_send>
3263	calls in the current loop iteration. Checking for async and signal events	3293	calls in the current loop iteration. Checking for async and signal events
3264	involves iterating over all running async watchers or all signal numbers.	3294	involves iterating over all running async watchers or all signal numbers.
3265		3295
3266	=back	3296	=back
3267		3297
3268		3298
3269	=head1 Win32 platform limitations and workarounds	3299	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3270		3300
3271	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3301	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3272	requires, and its I/O model is fundamentally incompatible with the POSIX	3302	requires, and its I/O model is fundamentally incompatible with the POSIX
3273	model. Libev still offers limited functionality on this platform in	3303	model. Libev still offers limited functionality on this platform in
3274	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3304	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
…		…
3281	way (note also that glib is the slowest event library known to man).	3311	way (note also that glib is the slowest event library known to man).
3282		3312
3283	There is no supported compilation method available on windows except	3313	There is no supported compilation method available on windows except
3284	embedding it into other applications.	3314	embedding it into other applications.
3285		3315
		3316	Not a libev limitation but worth mentioning: windows apparently doesn't
		3317	accept large writes: instead of resulting in a partial write, windows will
		3318	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3319	so make sure you only write small amounts into your sockets (less than a
		3320	megabyte seems safe, but thsi apparently depends on the amount of memory
		3321	available).
		3322
3286	Due to the many, low, and arbitrary limits on the win32 platform and	3323	Due to the many, low, and arbitrary limits on the win32 platform and
3287	the abysmal performance of winsockets, using a large number of sockets	3324	the abysmal performance of winsockets, using a large number of sockets
3288	is not recommended (and not reasonable). If your program needs to use	3325	is not recommended (and not reasonable). If your program needs to use
3289	more than a hundred or so sockets, then likely it needs to use a totally	3326	more than a hundred or so sockets, then likely it needs to use a totally
3290	different implementation for windows, as libev offers the POSIX readiness	3327	different implementation for windows, as libev offers the POSIX readiness
3291	notification model, which cannot be implemented efficiently on windows	3328	notification model, which cannot be implemented efficiently on windows
3292	(microsoft monopoly games).	3329	(Microsoft monopoly games).
		3330
		3331	A typical way to use libev under windows is to embed it (see the embedding
		3332	section for details) and use the following F<evwrap.h> header file instead
		3333	of F<ev.h>:
		3334
		3335	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3336	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3337
		3338	#include "ev.h"
		3339
		3340	And compile the following F<evwrap.c> file into your project (make sure
		3341	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3342
		3343	#include "evwrap.h"
		3344	#include "ev.c"
3293		3345
3294	=over 4	3346	=over 4
3295		3347
3296	=item The winsocket select function	3348	=item The winsocket select function
3297		3349
3298	The winsocket C<select> function doesn't follow POSIX in that it requires	3350	The winsocket C<select> function doesn't follow POSIX in that it
3299	socket I<handles> and not socket I<file descriptors>. This makes select	3351	requires socket I<handles> and not socket I<file descriptors> (it is
3300	very inefficient, and also requires a mapping from file descriptors	3352	also extremely buggy). This makes select very inefficient, and also
3301	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,	3353	requires a mapping from file descriptors to socket handles (the Microsoft
3302	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor	3354	C runtime provides the function C<_open_osfhandle> for this). See the
3303	symbols for more info.	3355	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3356	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3304		3357
3305	The configuration for a "naked" win32 using the microsoft runtime	3358	The configuration for a "naked" win32 using the Microsoft runtime
3306	libraries and raw winsocket select is:	3359	libraries and raw winsocket select is:
3307		3360
3308	#define EV_USE_SELECT 1	3361	#define EV_USE_SELECT 1
3309	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3362	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3310		3363
3311	Note that winsockets handling of fd sets is O(n), so you can easily get a	3364	Note that winsockets handling of fd sets is O(n), so you can easily get a
3312	complexity in the O(n²) range when using win32.	3365	complexity in the O(n²) range when using win32.
3313		3366
3314	=item Limited number of file descriptors	3367	=item Limited number of file descriptors
3315		3368
3316	Windows has numerous arbitrary (and low) limits on things.	3369	Windows has numerous arbitrary (and low) limits on things.
3317		3370
3318	Early versions of winsocket's select only supported waiting for a maximum	3371	Early versions of winsocket's select only supported waiting for a maximum
3319	of C<64> handles (probably owning to the fact that all windows kernels	3372	of C<64> handles (probably owning to the fact that all windows kernels
3320	can only wait for C<64> things at the same time internally; microsoft	3373	can only wait for C<64> things at the same time internally; Microsoft
3321	recommends spawning a chain of threads and wait for 63 handles and the	3374	recommends spawning a chain of threads and wait for 63 handles and the
3322	previous thread in each. Great).	3375	previous thread in each. Great).
3323		3376
3324	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3377	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3325	to some high number (e.g. C<2048>) before compiling the winsocket select	3378	to some high number (e.g. C<2048>) before compiling the winsocket select
3326	call (which might be in libev or elsewhere, for example, perl does its own	3379	call (which might be in libev or elsewhere, for example, perl does its own
3327	select emulation on windows).	3380	select emulation on windows).
3328		3381
3329	Another limit is the number of file descriptors in the microsoft runtime	3382	Another limit is the number of file descriptors in the Microsoft runtime
3330	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3383	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3331	or something like this inside microsoft). You can increase this by calling	3384	or something like this inside Microsoft). You can increase this by calling
3332	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3385	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3333	arbitrary limit), but is broken in many versions of the microsoft runtime	3386	arbitrary limit), but is broken in many versions of the Microsoft runtime
3334	libraries.	3387	libraries.
3335		3388
3336	This might get you to about C<512> or C<2048> sockets (depending on	3389	This might get you to about C<512> or C<2048> sockets (depending on
3337	windows version and/or the phase of the moon). To get more, you need to	3390	windows version and/or the phase of the moon). To get more, you need to
3338	wrap all I/O functions and provide your own fd management, but the cost of	3391	wrap all I/O functions and provide your own fd management, but the cost of
…		…
3345		3398
3346	In addition to a working ISO-C implementation, libev relies on a few	3399	In addition to a working ISO-C implementation, libev relies on a few
3347	additional extensions:	3400	additional extensions:
3348		3401
3349	=over 4	3402	=over 4
		3403
		3404	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3405	calling conventions regardless of C<ev_watcher_type *>.
		3406
		3407	Libev assumes not only that all watcher pointers have the same internal
		3408	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3409	assumes that the same (machine) code can be used to call any watcher
		3410	callback: The watcher callbacks have different type signatures, but libev
		3411	calls them using an C<ev_watcher *> internally.
3350		3412
3351	=item C<sig_atomic_t volatile> must be thread-atomic as well	3413	=item C<sig_atomic_t volatile> must be thread-atomic as well
3352		3414
3353	The type C<sig_atomic_t volatile> (or whatever is defined as	3415	The type C<sig_atomic_t volatile> (or whatever is defined as
3354	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different	3416	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
…		…
3386	=back	3448	=back
3387		3449
3388	If you know of other additional requirements drop me a note.	3450	If you know of other additional requirements drop me a note.
3389		3451
3390		3452
		3453	=head1 COMPILER WARNINGS
		3454
		3455	Depending on your compiler and compiler settings, you might get no or a
		3456	lot of warnings when compiling libev code. Some people are apparently
		3457	scared by this.
		3458
		3459	However, these are unavoidable for many reasons. For one, each compiler
		3460	has different warnings, and each user has different tastes regarding
		3461	warning options. "Warn-free" code therefore cannot be a goal except when
		3462	targeting a specific compiler and compiler-version.
		3463
		3464	Another reason is that some compiler warnings require elaborate
		3465	workarounds, or other changes to the code that make it less clear and less
		3466	maintainable.
		3467
		3468	And of course, some compiler warnings are just plain stupid, or simply
		3469	wrong (because they don't actually warn about the condition their message
		3470	seems to warn about).
		3471
		3472	While libev is written to generate as few warnings as possible,
		3473	"warn-free" code is not a goal, and it is recommended not to build libev
		3474	with any compiler warnings enabled unless you are prepared to cope with
		3475	them (e.g. by ignoring them). Remember that warnings are just that:
		3476	warnings, not errors, or proof of bugs.
		3477
		3478
3391	=head1 VALGRIND	3479	=head1 VALGRIND
3392		3480
3393	Valgrind has a special section here because it is a popular tool that is	3481	Valgrind has a special section here because it is a popular tool that is
3394	highly useful, but valgrind reports are very hard to interpret.	3482	highly useful, but valgrind reports are very hard to interpret.
3395		3483
…		…
3398		3486
3399	==2274== definitely lost: 0 bytes in 0 blocks.	3487	==2274== definitely lost: 0 bytes in 0 blocks.
3400	==2274== possibly lost: 0 bytes in 0 blocks.	3488	==2274== possibly lost: 0 bytes in 0 blocks.
3401	==2274== still reachable: 256 bytes in 1 blocks.	3489	==2274== still reachable: 256 bytes in 1 blocks.
3402		3490
3403	then there is no memory leak. Similarly, under some circumstances,	3491	Then there is no memory leak. Similarly, under some circumstances,
3404	valgrind might report kernel bugs as if it were a bug in libev, or it	3492	valgrind might report kernel bugs as if it were a bug in libev, or it
3405	might be confused (it is a very good tool, but only a tool).	3493	might be confused (it is a very good tool, but only a tool).
3406		3494
3407	If you are unsure about something, feel free to contact the mailing list	3495	If you are unsure about something, feel free to contact the mailing list
3408	with the full valgrind report and an explanation on why you think this is	3496	with the full valgrind report and an explanation on why you think this is

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