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Revision 1.163 by root, Sat May 31 23:19:23 2008 UTC vs.
Revision 1.179 by root, Sat Sep 13 19:14:21 2008 UTC

…		…
2		2
3	libev - a high performance full-featured event loop written in C	3	libev - a high performance full-featured event loop written in C
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
9	=head2 EXAMPLE PROGRAM	9	=head2 EXAMPLE PROGRAM
10		10
11	// a single header file is required	11	// a single header file is required
12	#include <ev.h>	12	#include <ev.h>
13		13
14	// every watcher type has its own typedef'd struct	14	// every watcher type has its own typedef'd struct
15	// with the name ev_<type>	15	// with the name ev_<type>
16	ev_io stdin_watcher;	16	ev_io stdin_watcher;
17	ev_timer timeout_watcher;	17	ev_timer timeout_watcher;
18		18
19	// all watcher callbacks have a similar signature	19	// all watcher callbacks have a similar signature
20	// this callback is called when data is readable on stdin	20	// this callback is called when data is readable on stdin
21	static void	21	static void
22	stdin_cb (EV_P_ struct ev_io *w, int revents)	22	stdin_cb (EV_P_ struct ev_io *w, int revents)
23	{	23	{
24	puts ("stdin ready");	24	puts ("stdin ready");
25	// for one-shot events, one must manually stop the watcher	25	// for one-shot events, one must manually stop the watcher
26	// with its corresponding stop function.	26	// with its corresponding stop function.
27	ev_io_stop (EV_A_ w);	27	ev_io_stop (EV_A_ w);
28		28
29	// this causes all nested ev_loop's to stop iterating	29	// this causes all nested ev_loop's to stop iterating
30	ev_unloop (EV_A_ EVUNLOOP_ALL);	30	ev_unloop (EV_A_ EVUNLOOP_ALL);
31	}	31	}
32		32
33	// another callback, this time for a time-out	33	// another callback, this time for a time-out
34	static void	34	static void
35	timeout_cb (EV_P_ struct ev_timer *w, int revents)	35	timeout_cb (EV_P_ struct ev_timer *w, int revents)
36	{	36	{
37	puts ("timeout");	37	puts ("timeout");
38	// this causes the innermost ev_loop to stop iterating	38	// this causes the innermost ev_loop to stop iterating
39	ev_unloop (EV_A_ EVUNLOOP_ONE);	39	ev_unloop (EV_A_ EVUNLOOP_ONE);
40	}	40	}
41		41
42	int	42	int
43	main (void)	43	main (void)
44	{	44	{
45	// use the default event loop unless you have special needs	45	// use the default event loop unless you have special needs
46	struct ev_loop *loop = ev_default_loop (0);	46	struct ev_loop *loop = ev_default_loop (0);
47		47
48	// initialise an io watcher, then start it	48	// initialise an io watcher, then start it
49	// this one will watch for stdin to become readable	49	// this one will watch for stdin to become readable
50	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);	50	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);
51	ev_io_start (loop, &stdin_watcher);	51	ev_io_start (loop, &stdin_watcher);
52		52
53	// initialise a timer watcher, then start it	53	// initialise a timer watcher, then start it
54	// simple non-repeating 5.5 second timeout	54	// simple non-repeating 5.5 second timeout
55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
56	ev_timer_start (loop, &timeout_watcher);	56	ev_timer_start (loop, &timeout_watcher);
57		57
58	// now wait for events to arrive	58	// now wait for events to arrive
59	ev_loop (loop, 0);	59	ev_loop (loop, 0);
60		60
61	// unloop was called, so exit	61	// unloop was called, so exit
62	return 0;	62	return 0;
63	}	63	}
64		64
65	=head1 DESCRIPTION	65	=head1 DESCRIPTION
66		66
67	The newest version of this document is also available as an html-formatted	67	The newest version of this document is also available as an html-formatted
68	web page you might find easier to navigate when reading it for the first	68	web page you might find easier to navigate when reading it for the first
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178	not a problem.	178	not a problem.
179		179
180	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
181	version.	181	version.
182		182
183	assert (("libev version mismatch",	183	assert (("libev version mismatch",
184	ev_version_major () == EV_VERSION_MAJOR	184	ev_version_major () == EV_VERSION_MAJOR
185	&& ev_version_minor () >= EV_VERSION_MINOR));	185	&& ev_version_minor () >= EV_VERSION_MINOR));
186		186
187	=item unsigned int ev_supported_backends ()	187	=item unsigned int ev_supported_backends ()
188		188
189	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_*>
190	value) compiled into this binary of libev (independent of their	190	value) compiled into this binary of libev (independent of their
…		…
192	a description of the set values.	192	a description of the set values.
193		193
194	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
195	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
196		196
197	assert (("sorry, no epoll, no sex",	197	assert (("sorry, no epoll, no sex",
198	ev_supported_backends () & EVBACKEND_EPOLL));	198	ev_supported_backends () & EVBACKEND_EPOLL));
199		199
200	=item unsigned int ev_recommended_backends ()	200	=item unsigned int ev_recommended_backends ()
201		201
202	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
203	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
…		…
359	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
360	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
361	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
362	readiness notifications you get per iteration.	362	readiness notifications you get per iteration.
363		363
		364	This backend maps C<EV_READ> to the C<readfds> set and C<EV_WRITE> to the
		365	C<writefds> set (and to work around Microsoft Windows bugs, also onto the
		366	C<exceptfds> set on that platform).
		367
364	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	368	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
365		369
366	And this is your standard poll(2) backend. It's more complicated	370	And this is your standard poll(2) backend. It's more complicated
367	than select, but handles sparse fds better and has no artificial	371	than select, but handles sparse fds better and has no artificial
368	limit on the number of fds you can use (except it will slow down	372	limit on the number of fds you can use (except it will slow down
369	considerably with a lot of inactive fds). It scales similarly to select,	373	considerably with a lot of inactive fds). It scales similarly to select,
370	i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for	374	i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for
371	performance tips.	375	performance tips.
		376
		377	This backend maps C<EV_READ> to C<POLLIN \| POLLERR \| POLLHUP>, and
		378	C<EV_WRITE> to C<POLLOUT \| POLLERR \| POLLHUP>.
372		379
373	=item C<EVBACKEND_EPOLL> (value 4, Linux)	380	=item C<EVBACKEND_EPOLL> (value 4, Linux)
374		381
375	For few fds, this backend is a bit little slower than poll and select,	382	For few fds, this backend is a bit little slower than poll and select,
376	but it scales phenomenally better. While poll and select usually scale	383	but it scales phenomenally better. While poll and select usually scale
…		…
395	keep at least one watcher active per fd at all times.	402	keep at least one watcher active per fd at all times.
396		403
397	While nominally embeddable in other event loops, this feature is broken in	404	While nominally embeddable in other event loops, this feature is broken in
398	all kernel versions tested so far.	405	all kernel versions tested so far.
399		406
		407	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
		408	C<EVBACKEND_POLL>.
		409
400	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	410	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
401		411
402	Kqueue deserves special mention, as at the time of this writing, it	412	Kqueue deserves special mention, as at the time of this writing, it
403	was broken on all BSDs except NetBSD (usually it doesn't work reliably	413	was broken on all BSDs except NetBSD (usually it doesn't work reliably
404	with anything but sockets and pipes, except on Darwin, where of course	414	with anything but sockets and pipes, except on Darwin, where of course
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425	almost everywhere, you should only use it when you have a lot of sockets	435	almost everywhere, you should only use it when you have a lot of sockets
426	(for which it usually works), by embedding it into another event loop	436	(for which it usually works), by embedding it into another event loop
427	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for	437	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for
428	sockets.	438	sockets.
429		439
		440	This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with
		441	C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with
		442	C<NOTE_EOF>.
		443
430	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	444	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
431		445
432	This is not implemented yet (and might never be, unless you send me an	446	This is not implemented yet (and might never be, unless you send me an
433	implementation). According to reports, C</dev/poll> only supports sockets	447	implementation). According to reports, C</dev/poll> only supports sockets
434	and is not embeddable, which would limit the usefulness of this backend	448	and is not embeddable, which would limit the usefulness of this backend
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450		464
451	On the positive side, ignoring the spurious readiness notifications, this	465	On the positive side, ignoring the spurious readiness notifications, this
452	backend actually performed to specification in all tests and is fully	466	backend actually performed to specification in all tests and is fully
453	embeddable, which is a rare feat among the OS-specific backends.	467	embeddable, which is a rare feat among the OS-specific backends.
454		468
		469	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
		470	C<EVBACKEND_POLL>.
		471
455	=item C<EVBACKEND_ALL>	472	=item C<EVBACKEND_ALL>
456		473
457	Try all backends (even potentially broken ones that wouldn't be tried	474	Try all backends (even potentially broken ones that wouldn't be tried
458	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	475	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
459	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	476	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
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466	backends will be tried (in the reverse order as listed here). If none are	483	backends will be tried (in the reverse order as listed here). If none are
467	specified, all backends in C<ev_recommended_backends ()> will be tried.	484	specified, all backends in C<ev_recommended_backends ()> will be tried.
468		485
469	The most typical usage is like this:	486	The most typical usage is like this:
470		487
471	if (!ev_default_loop (0))	488	if (!ev_default_loop (0))
472	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	489	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
473		490
474	Restrict libev to the select and poll backends, and do not allow	491	Restrict libev to the select and poll backends, and do not allow
475	environment settings to be taken into account:	492	environment settings to be taken into account:
476		493
477	ev_default_loop (EVBACKEND_POLL \| EVBACKEND_SELECT \| EVFLAG_NOENV);	494	ev_default_loop (EVBACKEND_POLL \| EVBACKEND_SELECT \| EVFLAG_NOENV);
478		495
479	Use whatever libev has to offer, but make sure that kqueue is used if	496	Use whatever libev has to offer, but make sure that kqueue is used if
480	available (warning, breaks stuff, best use only with your own private	497	available (warning, breaks stuff, best use only with your own private
481	event loop and only if you know the OS supports your types of fds):	498	event loop and only if you know the OS supports your types of fds):
482		499
483	ev_default_loop (ev_recommended_backends () \| EVBACKEND_KQUEUE);	500	ev_default_loop (ev_recommended_backends () \| EVBACKEND_KQUEUE);
484		501
485	=item struct ev_loop *ev_loop_new (unsigned int flags)	502	=item struct ev_loop *ev_loop_new (unsigned int flags)
486		503
487	Similar to C<ev_default_loop>, but always creates a new event loop that is	504	Similar to C<ev_default_loop>, but always creates a new event loop that is
488	always distinct from the default loop. Unlike the default loop, it cannot	505	always distinct from the default loop. Unlike the default loop, it cannot
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493	libev with threads is indeed to create one loop per thread, and using the	510	libev with threads is indeed to create one loop per thread, and using the
494	default loop in the "main" or "initial" thread.	511	default loop in the "main" or "initial" thread.
495		512
496	Example: Try to create a event loop that uses epoll and nothing else.	513	Example: Try to create a event loop that uses epoll and nothing else.
497		514
498	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	515	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
499	if (!epoller)	516	if (!epoller)
500	fatal ("no epoll found here, maybe it hides under your chair");	517	fatal ("no epoll found here, maybe it hides under your chair");
501		518
502	=item ev_default_destroy ()	519	=item ev_default_destroy ()
503		520
504	Destroys the default loop again (frees all memory and kernel state	521	Destroys the default loop again (frees all memory and kernel state
505	etc.). None of the active event watchers will be stopped in the normal	522	etc.). None of the active event watchers will be stopped in the normal
…		…
573	received events and started processing them. This timestamp does not	590	received events and started processing them. This timestamp does not
574	change as long as callbacks are being processed, and this is also the base	591	change as long as callbacks are being processed, and this is also the base
575	time used for relative timers. You can treat it as the timestamp of the	592	time used for relative timers. You can treat it as the timestamp of the
576	event occurring (or more correctly, libev finding out about it).	593	event occurring (or more correctly, libev finding out about it).
577		594
		595	=item ev_now_update (loop)
		596
		597	Establishes the current time by querying the kernel, updating the time
		598	returned by C<ev_now ()> in the progress. This is a costly operation and
		599	is usually done automatically within C<ev_loop ()>.
		600
		601	This function is rarely useful, but when some event callback runs for a
		602	very long time without entering the event loop, updating libev's idea of
		603	the current time is a good idea.
		604
		605	See also "The special problem of time updates" in the C<ev_timer> section.
		606
578	=item ev_loop (loop, int flags)	607	=item ev_loop (loop, int flags)
579		608
580	Finally, this is it, the event handler. This function usually is called	609	Finally, this is it, the event handler. This function usually is called
581	after you initialised all your watchers and you want to start handling	610	after you initialised all your watchers and you want to start handling
582	events.	611	events.
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604		633
605	Here are the gory details of what C<ev_loop> does:	634	Here are the gory details of what C<ev_loop> does:
606		635
607	- Before the first iteration, call any pending watchers.	636	- Before the first iteration, call any pending watchers.
608	* If EVFLAG_FORKCHECK was used, check for a fork.	637	* If EVFLAG_FORKCHECK was used, check for a fork.
609	- If a fork was detected, queue and call all fork watchers.	638	- If a fork was detected (by any means), queue and call all fork watchers.
610	- Queue and call all prepare watchers.	639	- Queue and call all prepare watchers.
611	- If we have been forked, recreate the kernel state.	640	- If we have been forked, detach and recreate the kernel state
		641	as to not disturb the other process.
612	- Update the kernel state with all outstanding changes.	642	- Update the kernel state with all outstanding changes.
613	- Update the "event loop time".	643	- Update the "event loop time" (ev_now ()).
614	- Calculate for how long to sleep or block, if at all	644	- Calculate for how long to sleep or block, if at all
615	(active idle watchers, EVLOOP_NONBLOCK or not having	645	(active idle watchers, EVLOOP_NONBLOCK or not having
616	any active watchers at all will result in not sleeping).	646	any active watchers at all will result in not sleeping).
617	- Sleep if the I/O and timer collect interval say so.	647	- Sleep if the I/O and timer collect interval say so.
618	- Block the process, waiting for any events.	648	- Block the process, waiting for any events.
619	- Queue all outstanding I/O (fd) events.	649	- Queue all outstanding I/O (fd) events.
620	- Update the "event loop time" and do time jump handling.	650	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
621	- Queue all outstanding timers.	651	- Queue all outstanding timers.
622	- Queue all outstanding periodics.	652	- Queue all outstanding periodics.
623	- If no events are pending now, queue all idle watchers.	653	- Unless any events are pending now, queue all idle watchers.
624	- Queue all check watchers.	654	- Queue all check watchers.
625	- Call all queued watchers in reverse order (i.e. check watchers first).	655	- Call all queued watchers in reverse order (i.e. check watchers first).
626	Signals and child watchers are implemented as I/O watchers, and will	656	Signals and child watchers are implemented as I/O watchers, and will
627	be handled here by queueing them when their watcher gets executed.	657	be handled here by queueing them when their watcher gets executed.
628	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	658	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
…		…
633	anymore.	663	anymore.
634		664
635	... queue jobs here, make sure they register event watchers as long	665	... queue jobs here, make sure they register event watchers as long
636	... as they still have work to do (even an idle watcher will do..)	666	... as they still have work to do (even an idle watcher will do..)
637	ev_loop (my_loop, 0);	667	ev_loop (my_loop, 0);
638	... jobs done. yeah!	668	... jobs done or somebody called unloop. yeah!
639		669
640	=item ev_unloop (loop, how)	670	=item ev_unloop (loop, how)
641		671
642	Can be used to make a call to C<ev_loop> return early (but only after it	672	Can be used to make a call to C<ev_loop> return early (but only after it
643	has processed all outstanding events). The C<how> argument must be either	673	has processed all outstanding events). The C<how> argument must be either
…		…
664	respectively).	694	respectively).
665		695
666	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	696	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
667	running when nothing else is active.	697	running when nothing else is active.
668		698
669	struct ev_signal exitsig;	699	struct ev_signal exitsig;
670	ev_signal_init (&exitsig, sig_cb, SIGINT);	700	ev_signal_init (&exitsig, sig_cb, SIGINT);
671	ev_signal_start (loop, &exitsig);	701	ev_signal_start (loop, &exitsig);
672	evf_unref (loop);	702	evf_unref (loop);
673		703
674	Example: For some weird reason, unregister the above signal handler again.	704	Example: For some weird reason, unregister the above signal handler again.
675		705
676	ev_ref (loop);	706	ev_ref (loop);
677	ev_signal_stop (loop, &exitsig);	707	ev_signal_stop (loop, &exitsig);
678		708
679	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	709	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
680		710
681	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	711	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
682		712
683	These advanced functions influence the time that libev will spend waiting	713	These advanced functions influence the time that libev will spend waiting
684	for events. Both are by default C<0>, meaning that libev will try to	714	for events. Both time intervals are by default C<0>, meaning that libev
685	invoke timer/periodic callbacks and I/O callbacks with minimum latency.	715	will try to invoke timer/periodic callbacks and I/O callbacks with minimum
		716	latency.
686		717
687	Setting these to a higher value (the C<interval> I<must> be >= C<0>)	718	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
688	allows libev to delay invocation of I/O and timer/periodic callbacks to	719	allows libev to delay invocation of I/O and timer/periodic callbacks
689	increase efficiency of loop iterations.	720	to increase efficiency of loop iterations (or to increase power-saving
		721	opportunities).
690		722
691	The background is that sometimes your program runs just fast enough to	723	The background is that sometimes your program runs just fast enough to
692	handle one (or very few) event(s) per loop iteration. While this makes	724	handle one (or very few) event(s) per loop iteration. While this makes
693	the program responsive, it also wastes a lot of CPU time to poll for new	725	the program responsive, it also wastes a lot of CPU time to poll for new
694	events, especially with backends like C<select ()> which have a high	726	events, especially with backends like C<select ()> which have a high
…		…
710	interval to a value near C<0.1> or so, which is often enough for	742	interval to a value near C<0.1> or so, which is often enough for
711	interactive servers (of course not for games), likewise for timeouts. It	743	interactive servers (of course not for games), likewise for timeouts. It
712	usually doesn't make much sense to set it to a lower value than C<0.01>,	744	usually doesn't make much sense to set it to a lower value than C<0.01>,
713	as this approaches the timing granularity of most systems.	745	as this approaches the timing granularity of most systems.
714		746
		747	Setting the I<timeout collect interval> can improve the opportunity for
		748	saving power, as the program will "bundle" timer callback invocations that
		749	are "near" in time together, by delaying some, thus reducing the number of
		750	times the process sleeps and wakes up again. Another useful technique to
		751	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
		752	they fire on, say, one-second boundaries only.
		753
715	=item ev_loop_verify (loop)	754	=item ev_loop_verify (loop)
716		755
717	This function only does something when C<EV_VERIFY> support has been	756	This function only does something when C<EV_VERIFY> support has been
718	compiled in. It tries to go through all internal structures and checks	757	compiled in. It tries to go through all internal structures and checks
719	them for validity. If anything is found to be inconsistent, it will print	758	them for validity. If anything is found to be inconsistent, it will print
…		…
730		769
731	A watcher is a structure that you create and register to record your	770	A watcher is a structure that you create and register to record your
732	interest in some event. For instance, if you want to wait for STDIN to	771	interest in some event. For instance, if you want to wait for STDIN to
733	become readable, you would create an C<ev_io> watcher for that:	772	become readable, you would create an C<ev_io> watcher for that:
734		773
735	static void my_cb (struct ev_loop loop, struct ev_io w, int revents)	774	static void my_cb (struct ev_loop loop, struct ev_io w, int revents)
736	{	775	{
737	ev_io_stop (w);	776	ev_io_stop (w);
738	ev_unloop (loop, EVUNLOOP_ALL);	777	ev_unloop (loop, EVUNLOOP_ALL);
739	}	778	}
740		779
741	struct ev_loop *loop = ev_default_loop (0);	780	struct ev_loop *loop = ev_default_loop (0);
742	struct ev_io stdin_watcher;	781	struct ev_io stdin_watcher;
743	ev_init (&stdin_watcher, my_cb);	782	ev_init (&stdin_watcher, my_cb);
744	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	783	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
745	ev_io_start (loop, &stdin_watcher);	784	ev_io_start (loop, &stdin_watcher);
746	ev_loop (loop, 0);	785	ev_loop (loop, 0);
747		786
748	As you can see, you are responsible for allocating the memory for your	787	As you can see, you are responsible for allocating the memory for your
749	watcher structures (and it is usually a bad idea to do this on the stack,	788	watcher structures (and it is usually a bad idea to do this on the stack,
750	although this can sometimes be quite valid).	789	although this can sometimes be quite valid).
751		790
…		…
978	to associate arbitrary data with your watcher. If you need more data and	1017	to associate arbitrary data with your watcher. If you need more data and
979	don't want to allocate memory and store a pointer to it in that data	1018	don't want to allocate memory and store a pointer to it in that data
980	member, you can also "subclass" the watcher type and provide your own	1019	member, you can also "subclass" the watcher type and provide your own
981	data:	1020	data:
982		1021
983	struct my_io	1022	struct my_io
984	{	1023	{
985	struct ev_io io;	1024	struct ev_io io;
986	int otherfd;	1025	int otherfd;
987	void *somedata;	1026	void *somedata;
988	struct whatever *mostinteresting;	1027	struct whatever *mostinteresting;
989	}	1028	};
		1029
		1030	...
		1031	struct my_io w;
		1032	ev_io_init (&w.io, my_cb, fd, EV_READ);
990		1033
991	And since your callback will be called with a pointer to the watcher, you	1034	And since your callback will be called with a pointer to the watcher, you
992	can cast it back to your own type:	1035	can cast it back to your own type:
993		1036
994	static void my_cb (struct ev_loop loop, struct ev_io w_, int revents)	1037	static void my_cb (struct ev_loop loop, struct ev_io w_, int revents)
995	{	1038	{
996	struct my_io w = (struct my_io )w_;	1039	struct my_io w = (struct my_io )w_;
997	...	1040	...
998	}	1041	}
999		1042
1000	More interesting and less C-conformant ways of casting your callback type	1043	More interesting and less C-conformant ways of casting your callback type
1001	instead have been omitted.	1044	instead have been omitted.
1002		1045
1003	Another common scenario is having some data structure with multiple	1046	Another common scenario is to use some data structure with multiple
1004	watchers:	1047	embedded watchers:
1005		1048
1006	struct my_biggy	1049	struct my_biggy
1007	{	1050	{
1008	int some_data;	1051	int some_data;
1009	ev_timer t1;	1052	ev_timer t1;
1010	ev_timer t2;	1053	ev_timer t2;
1011	}	1054	}
1012		1055
1013	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1056	In this case getting the pointer to C<my_biggy> is a bit more
1014	you need to use C<offsetof>:	1057	complicated: Either you store the address of your C<my_biggy> struct
		1058	in the C<data> member of the watcher, or you need to use some pointer
		1059	arithmetic using C<offsetof> inside your watchers:
1015		1060
1016	#include <stddef.h>	1061	#include <stddef.h>
1017		1062
1018	static void	1063	static void
1019	t1_cb (EV_P_ struct ev_timer *w, int revents)	1064	t1_cb (EV_P_ struct ev_timer *w, int revents)
1020	{	1065	{
1021	struct my_biggy big = (struct my_biggy *	1066	struct my_biggy big = (struct my_biggy *
1022	(((char *)w) - offsetof (struct my_biggy, t1));	1067	(((char *)w) - offsetof (struct my_biggy, t1));
1023	}	1068	}
1024		1069
1025	static void	1070	static void
1026	t2_cb (EV_P_ struct ev_timer *w, int revents)	1071	t2_cb (EV_P_ struct ev_timer *w, int revents)
1027	{	1072	{
1028	struct my_biggy big = (struct my_biggy *	1073	struct my_biggy big = (struct my_biggy *
1029	(((char *)w) - offsetof (struct my_biggy, t2));	1074	(((char *)w) - offsetof (struct my_biggy, t2));
1030	}	1075	}
1031		1076
1032		1077
1033	=head1 WATCHER TYPES	1078	=head1 WATCHER TYPES
1034		1079
1035	This section describes each watcher in detail, but will not repeat	1080	This section describes each watcher in detail, but will not repeat
…		…
1124	C<EVBACKEND_POLL>.	1169	C<EVBACKEND_POLL>.
1125		1170
1126	=head3 The special problem of SIGPIPE	1171	=head3 The special problem of SIGPIPE
1127		1172
1128	While not really specific to libev, it is easy to forget about SIGPIPE:	1173	While not really specific to libev, it is easy to forget about SIGPIPE:
1129	when reading from a pipe whose other end has been closed, your program	1174	when writing to a pipe whose other end has been closed, your program gets
1130	gets send a SIGPIPE, which, by default, aborts your program. For most	1175	send a SIGPIPE, which, by default, aborts your program. For most programs
1131	programs this is sensible behaviour, for daemons, this is usually	1176	this is sensible behaviour, for daemons, this is usually undesirable.
1132	undesirable.
1133		1177
1134	So when you encounter spurious, unexplained daemon exits, make sure you	1178	So when you encounter spurious, unexplained daemon exits, make sure you
1135	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1179	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1136	somewhere, as that would have given you a big clue).	1180	somewhere, as that would have given you a big clue).
1137		1181
…		…
1162		1206
1163	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1207	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1164	readable, but only once. Since it is likely line-buffered, you could	1208	readable, but only once. Since it is likely line-buffered, you could
1165	attempt to read a whole line in the callback.	1209	attempt to read a whole line in the callback.
1166		1210
1167	static void	1211	static void
1168	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	1212	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
1169	{	1213	{
1170	ev_io_stop (loop, w);	1214	ev_io_stop (loop, w);
1171	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1215	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1172	}	1216	}
1173		1217
1174	...	1218	...
1175	struct ev_loop *loop = ev_default_init (0);	1219	struct ev_loop *loop = ev_default_init (0);
1176	struct ev_io stdin_readable;	1220	struct ev_io stdin_readable;
1177	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1221	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1178	ev_io_start (loop, &stdin_readable);	1222	ev_io_start (loop, &stdin_readable);
1179	ev_loop (loop, 0);	1223	ev_loop (loop, 0);
1180		1224
1181		1225
1182	=head2 C<ev_timer> - relative and optionally repeating timeouts	1226	=head2 C<ev_timer> - relative and optionally repeating timeouts
1183		1227
1184	Timer watchers are simple relative timers that generate an event after a	1228	Timer watchers are simple relative timers that generate an event after a
…		…
1188	times out after an hour and you reset your system clock to January last	1232	times out after an hour and you reset your system clock to January last
1189	year, it will still time out after (roughly) and hour. "Roughly" because	1233	year, it will still time out after (roughly) and hour. "Roughly" because
1190	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1234	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1191	monotonic clock option helps a lot here).	1235	monotonic clock option helps a lot here).
1192		1236
		1237	The callback is guaranteed to be invoked only after its timeout has passed,
		1238	but if multiple timers become ready during the same loop iteration then
		1239	order of execution is undefined.
		1240
		1241	=head3 The special problem of time updates
		1242
		1243	Establishing the current time is a costly operation (it usually takes at
		1244	least two system calls): EV therefore updates its idea of the current
		1245	time only before and after C<ev_loop> polls for new events, which causes
		1246	a growing difference between C<ev_now ()> and C<ev_time ()> when handling
		1247	lots of events.
		1248
1193	The relative timeouts are calculated relative to the C<ev_now ()>	1249	The relative timeouts are calculated relative to the C<ev_now ()>
1194	time. This is usually the right thing as this timestamp refers to the time	1250	time. This is usually the right thing as this timestamp refers to the time
1195	of the event triggering whatever timeout you are modifying/starting. If	1251	of the event triggering whatever timeout you are modifying/starting. If
1196	you suspect event processing to be delayed and you I<need> to base the timeout	1252	you suspect event processing to be delayed and you I<need> to base the
1197	on the current time, use something like this to adjust for this:	1253	timeout on the current time, use something like this to adjust for this:
1198		1254
1199	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1255	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1200		1256
1201	The callback is guaranteed to be invoked only after its timeout has passed,	1257	If the event loop is suspended for a long time, you can also force an
1202	but if multiple timers become ready during the same loop iteration then	1258	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1203	order of execution is undefined.	1259	()>.
1204		1260
1205	=head3 Watcher-Specific Functions and Data Members	1261	=head3 Watcher-Specific Functions and Data Members
1206		1262
1207	=over 4	1263	=over 4
1208		1264
…		…
1269		1325
1270	=head3 Examples	1326	=head3 Examples
1271		1327
1272	Example: Create a timer that fires after 60 seconds.	1328	Example: Create a timer that fires after 60 seconds.
1273		1329
1274	static void	1330	static void
1275	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	1331	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
1276	{	1332	{
1277	.. one minute over, w is actually stopped right here	1333	.. one minute over, w is actually stopped right here
1278	}	1334	}
1279		1335
1280	struct ev_timer mytimer;	1336	struct ev_timer mytimer;
1281	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1337	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1282	ev_timer_start (loop, &mytimer);	1338	ev_timer_start (loop, &mytimer);
1283		1339
1284	Example: Create a timeout timer that times out after 10 seconds of	1340	Example: Create a timeout timer that times out after 10 seconds of
1285	inactivity.	1341	inactivity.
1286		1342
1287	static void	1343	static void
1288	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1344	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
1289	{	1345	{
1290	.. ten seconds without any activity	1346	.. ten seconds without any activity
1291	}	1347	}
1292		1348
1293	struct ev_timer mytimer;	1349	struct ev_timer mytimer;
1294	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1350	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1295	ev_timer_again (&mytimer); /* start timer */	1351	ev_timer_again (&mytimer); /* start timer */
1296	ev_loop (loop, 0);	1352	ev_loop (loop, 0);
1297		1353
1298	// and in some piece of code that gets executed on any "activity":	1354	// and in some piece of code that gets executed on any "activity":
1299	// reset the timeout to start ticking again at 10 seconds	1355	// reset the timeout to start ticking again at 10 seconds
1300	ev_timer_again (&mytimer);	1356	ev_timer_again (&mytimer);
1301		1357
1302		1358
1303	=head2 C<ev_periodic> - to cron or not to cron?	1359	=head2 C<ev_periodic> - to cron or not to cron?
1304		1360
1305	Periodic watchers are also timers of a kind, but they are very versatile	1361	Periodic watchers are also timers of a kind, but they are very versatile
…		…
1448		1504
1449	Example: Call a callback every hour, or, more precisely, whenever the	1505	Example: Call a callback every hour, or, more precisely, whenever the
1450	system clock is divisible by 3600. The callback invocation times have	1506	system clock is divisible by 3600. The callback invocation times have
1451	potentially a lot of jitter, but good long-term stability.	1507	potentially a lot of jitter, but good long-term stability.
1452		1508
1453	static void	1509	static void
1454	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1510	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
1455	{	1511	{
1456	... its now a full hour (UTC, or TAI or whatever your clock follows)	1512	... its now a full hour (UTC, or TAI or whatever your clock follows)
1457	}	1513	}
1458		1514
1459	struct ev_periodic hourly_tick;	1515	struct ev_periodic hourly_tick;
1460	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1516	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1461	ev_periodic_start (loop, &hourly_tick);	1517	ev_periodic_start (loop, &hourly_tick);
1462		1518
1463	Example: The same as above, but use a reschedule callback to do it:	1519	Example: The same as above, but use a reschedule callback to do it:
1464		1520
1465	#include <math.h>	1521	#include <math.h>
1466		1522
1467	static ev_tstamp	1523	static ev_tstamp
1468	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1524	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1469	{	1525	{
1470	return fmod (now, 3600.) + 3600.;	1526	return fmod (now, 3600.) + 3600.;
1471	}	1527	}
1472		1528
1473	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1529	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1474		1530
1475	Example: Call a callback every hour, starting now:	1531	Example: Call a callback every hour, starting now:
1476		1532
1477	struct ev_periodic hourly_tick;	1533	struct ev_periodic hourly_tick;
1478	ev_periodic_init (&hourly_tick, clock_cb,	1534	ev_periodic_init (&hourly_tick, clock_cb,
1479	fmod (ev_now (loop), 3600.), 3600., 0);	1535	fmod (ev_now (loop), 3600.), 3600., 0);
1480	ev_periodic_start (loop, &hourly_tick);	1536	ev_periodic_start (loop, &hourly_tick);
1481		1537
1482		1538
1483	=head2 C<ev_signal> - signal me when a signal gets signalled!	1539	=head2 C<ev_signal> - signal me when a signal gets signalled!
1484		1540
1485	Signal watchers will trigger an event when the process receives a specific	1541	Signal watchers will trigger an event when the process receives a specific
…		…
1519		1575
1520	=head3 Examples	1576	=head3 Examples
1521		1577
1522	Example: Try to exit cleanly on SIGINT and SIGTERM.	1578	Example: Try to exit cleanly on SIGINT and SIGTERM.
1523		1579
1524	static void	1580	static void
1525	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1581	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1526	{	1582	{
1527	ev_unloop (loop, EVUNLOOP_ALL);	1583	ev_unloop (loop, EVUNLOOP_ALL);
1528	}	1584	}
1529		1585
1530	struct ev_signal signal_watcher;	1586	struct ev_signal signal_watcher;
1531	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1587	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1532	ev_signal_start (loop, &sigint_cb);	1588	ev_signal_start (loop, &sigint_cb);
1533		1589
1534		1590
1535	=head2 C<ev_child> - watch out for process status changes	1591	=head2 C<ev_child> - watch out for process status changes
1536		1592
1537	Child watchers trigger when your process receives a SIGCHLD in response to	1593	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1559	handler, you can override it easily by installing your own handler for	1615	handler, you can override it easily by installing your own handler for
1560	C<SIGCHLD> after initialising the default loop, and making sure the	1616	C<SIGCHLD> after initialising the default loop, and making sure the
1561	default loop never gets destroyed. You are encouraged, however, to use an	1617	default loop never gets destroyed. You are encouraged, however, to use an
1562	event-based approach to child reaping and thus use libev's support for	1618	event-based approach to child reaping and thus use libev's support for
1563	that, so other libev users can use C<ev_child> watchers freely.	1619	that, so other libev users can use C<ev_child> watchers freely.
		1620
		1621	=head3 Stopping the Child Watcher
		1622
		1623	Currently, the child watcher never gets stopped, even when the
		1624	child terminates, so normally one needs to stop the watcher in the
		1625	callback. Future versions of libev might stop the watcher automatically
		1626	when a child exit is detected.
1564		1627
1565	=head3 Watcher-Specific Functions and Data Members	1628	=head3 Watcher-Specific Functions and Data Members
1566		1629
1567	=over 4	1630	=over 4
1568		1631
…		…
1597	=head3 Examples	1660	=head3 Examples
1598		1661
1599	Example: C<fork()> a new process and install a child handler to wait for	1662	Example: C<fork()> a new process and install a child handler to wait for
1600	its completion.	1663	its completion.
1601		1664
1602	ev_child cw;	1665	ev_child cw;
1603		1666
1604	static void	1667	static void
1605	child_cb (EV_P_ struct ev_child *w, int revents)	1668	child_cb (EV_P_ struct ev_child *w, int revents)
1606	{	1669	{
1607	ev_child_stop (EV_A_ w);	1670	ev_child_stop (EV_A_ w);
1608	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1671	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1609	}	1672	}
1610		1673
1611	pid_t pid = fork ();	1674	pid_t pid = fork ();
1612		1675
1613	if (pid < 0)	1676	if (pid < 0)
1614	// error	1677	// error
1615	else if (pid == 0)	1678	else if (pid == 0)
1616	{	1679	{
1617	// the forked child executes here	1680	// the forked child executes here
1618	exit (1);	1681	exit (1);
1619	}	1682	}
1620	else	1683	else
1621	{	1684	{
1622	ev_child_init (&cw, child_cb, pid, 0);	1685	ev_child_init (&cw, child_cb, pid, 0);
1623	ev_child_start (EV_DEFAULT_ &cw);	1686	ev_child_start (EV_DEFAULT_ &cw);
1624	}	1687	}
1625		1688
1626		1689
1627	=head2 C<ev_stat> - did the file attributes just change?	1690	=head2 C<ev_stat> - did the file attributes just change?
1628		1691
1629	This watches a file system path for attribute changes. That is, it calls	1692	This watches a file system path for attribute changes. That is, it calls
…		…
1662	will be no polling.	1725	will be no polling.
1663		1726
1664	=head3 ABI Issues (Largefile Support)	1727	=head3 ABI Issues (Largefile Support)
1665		1728
1666	Libev by default (unless the user overrides this) uses the default	1729	Libev by default (unless the user overrides this) uses the default
1667	compilation environment, which means that on systems with optionally	1730	compilation environment, which means that on systems with large file
1668	disabled large file support, you get the 32 bit version of the stat	1731	support disabled by default, you get the 32 bit version of the stat
1669	structure. When using the library from programs that change the ABI to	1732	structure. When using the library from programs that change the ABI to
1670	use 64 bit file offsets the programs will fail. In that case you have to	1733	use 64 bit file offsets the programs will fail. In that case you have to
1671	compile libev with the same flags to get binary compatibility. This is	1734	compile libev with the same flags to get binary compatibility. This is
1672	obviously the case with any flags that change the ABI, but the problem is	1735	obviously the case with any flags that change the ABI, but the problem is
1673	most noticeably with ev_stat and large file support.	1736	most noticeably disabled with ev_stat and large file support.
		1737
		1738	The solution for this is to lobby your distribution maker to make large
		1739	file interfaces available by default (as e.g. FreeBSD does) and not
		1740	optional. Libev cannot simply switch on large file support because it has
		1741	to exchange stat structures with application programs compiled using the
		1742	default compilation environment.
1674		1743
1675	=head3 Inotify	1744	=head3 Inotify
1676		1745
1677	When C<inotify (7)> support has been compiled into libev (generally only	1746	When C<inotify (7)> support has been compiled into libev (generally only
1678	available on Linux) and present at runtime, it will be used to speed up	1747	available on Linux) and present at runtime, it will be used to speed up
…		…
1767		1836
1768	=head3 Examples	1837	=head3 Examples
1769		1838
1770	Example: Watch C</etc/passwd> for attribute changes.	1839	Example: Watch C</etc/passwd> for attribute changes.
1771		1840
1772	static void	1841	static void
1773	passwd_cb (struct ev_loop loop, ev_stat w, int revents)	1842	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
1774	{	1843	{
1775	/* /etc/passwd changed in some way */	1844	/* /etc/passwd changed in some way */
1776	if (w->attr.st_nlink)	1845	if (w->attr.st_nlink)
1777	{	1846	{
1778	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1847	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1779	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1848	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1780	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1849	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1781	}	1850	}
1782	else	1851	else
1783	/* you shalt not abuse printf for puts */	1852	/* you shalt not abuse printf for puts */
1784	puts ("wow, /etc/passwd is not there, expect problems. "	1853	puts ("wow, /etc/passwd is not there, expect problems. "
1785	"if this is windows, they already arrived\n");	1854	"if this is windows, they already arrived\n");
1786	}	1855	}
1787		1856
1788	...	1857	...
1789	ev_stat passwd;	1858	ev_stat passwd;
1790		1859
1791	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1860	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1792	ev_stat_start (loop, &passwd);	1861	ev_stat_start (loop, &passwd);
1793		1862
1794	Example: Like above, but additionally use a one-second delay so we do not	1863	Example: Like above, but additionally use a one-second delay so we do not
1795	miss updates (however, frequent updates will delay processing, too, so	1864	miss updates (however, frequent updates will delay processing, too, so
1796	one might do the work both on C<ev_stat> callback invocation I<and> on	1865	one might do the work both on C<ev_stat> callback invocation I<and> on
1797	C<ev_timer> callback invocation).	1866	C<ev_timer> callback invocation).
1798		1867
1799	static ev_stat passwd;	1868	static ev_stat passwd;
1800	static ev_timer timer;	1869	static ev_timer timer;
1801		1870
1802	static void	1871	static void
1803	timer_cb (EV_P_ ev_timer *w, int revents)	1872	timer_cb (EV_P_ ev_timer *w, int revents)
1804	{	1873	{
1805	ev_timer_stop (EV_A_ w);	1874	ev_timer_stop (EV_A_ w);
1806		1875
1807	/* now it's one second after the most recent passwd change */	1876	/* now it's one second after the most recent passwd change */
1808	}	1877	}
1809		1878
1810	static void	1879	static void
1811	stat_cb (EV_P_ ev_stat *w, int revents)	1880	stat_cb (EV_P_ ev_stat *w, int revents)
1812	{	1881	{
1813	/* reset the one-second timer */	1882	/* reset the one-second timer */
1814	ev_timer_again (EV_A_ &timer);	1883	ev_timer_again (EV_A_ &timer);
1815	}	1884	}
1816		1885
1817	...	1886	...
1818	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1887	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1819	ev_stat_start (loop, &passwd);	1888	ev_stat_start (loop, &passwd);
1820	ev_timer_init (&timer, timer_cb, 0., 1.02);	1889	ev_timer_init (&timer, timer_cb, 0., 1.02);
1821		1890
1822		1891
1823	=head2 C<ev_idle> - when you've got nothing better to do...	1892	=head2 C<ev_idle> - when you've got nothing better to do...
1824		1893
1825	Idle watchers trigger events when no other events of the same or higher	1894	Idle watchers trigger events when no other events of the same or higher
…		…
1856	=head3 Examples	1925	=head3 Examples
1857		1926
1858	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1927	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1859	callback, free it. Also, use no error checking, as usual.	1928	callback, free it. Also, use no error checking, as usual.
1860		1929
1861	static void	1930	static void
1862	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1931	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1863	{	1932	{
1864	free (w);	1933	free (w);
1865	// now do something you wanted to do when the program has	1934	// now do something you wanted to do when the program has
1866	// no longer anything immediate to do.	1935	// no longer anything immediate to do.
1867	}	1936	}
1868		1937
1869	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1938	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1870	ev_idle_init (idle_watcher, idle_cb);	1939	ev_idle_init (idle_watcher, idle_cb);
1871	ev_idle_start (loop, idle_cb);	1940	ev_idle_start (loop, idle_cb);
1872		1941
1873		1942
1874	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1943	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1875		1944
1876	Prepare and check watchers are usually (but not always) used in tandem:	1945	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1948	and in a check watcher, destroy them and call into libadns. What follows	2017	and in a check watcher, destroy them and call into libadns. What follows
1949	is pseudo-code only of course. This requires you to either use a low	2018	is pseudo-code only of course. This requires you to either use a low
1950	priority for the check watcher or use C<ev_clear_pending> explicitly, as	2019	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1951	the callbacks for the IO/timeout watchers might not have been called yet.	2020	the callbacks for the IO/timeout watchers might not have been called yet.
1952		2021
1953	static ev_io iow [nfd];	2022	static ev_io iow [nfd];
1954	static ev_timer tw;	2023	static ev_timer tw;
1955		2024
1956	static void	2025	static void
1957	io_cb (ev_loop loop, ev_io w, int revents)	2026	io_cb (ev_loop loop, ev_io w, int revents)
1958	{	2027	{
1959	}	2028	}
1960		2029
1961	// create io watchers for each fd and a timer before blocking	2030	// create io watchers for each fd and a timer before blocking
1962	static void	2031	static void
1963	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	2032	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1964	{	2033	{
1965	int timeout = 3600000;	2034	int timeout = 3600000;
1966	struct pollfd fds [nfd];	2035	struct pollfd fds [nfd];
1967	// actual code will need to loop here and realloc etc.	2036	// actual code will need to loop here and realloc etc.
1968	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	2037	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1969		2038
1970	/* the callback is illegal, but won't be called as we stop during check */	2039	/* the callback is illegal, but won't be called as we stop during check */
1971	ev_timer_init (&tw, 0, timeout * 1e-3);	2040	ev_timer_init (&tw, 0, timeout * 1e-3);
1972	ev_timer_start (loop, &tw);	2041	ev_timer_start (loop, &tw);
1973		2042
1974	// create one ev_io per pollfd	2043	// create one ev_io per pollfd
1975	for (int i = 0; i < nfd; ++i)	2044	for (int i = 0; i < nfd; ++i)
1976	{	2045	{
1977	ev_io_init (iow + i, io_cb, fds [i].fd,	2046	ev_io_init (iow + i, io_cb, fds [i].fd,
1978	((fds [i].events & POLLIN ? EV_READ : 0)	2047	((fds [i].events & POLLIN ? EV_READ : 0)
1979	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	2048	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1980		2049
1981	fds [i].revents = 0;	2050	fds [i].revents = 0;
1982	ev_io_start (loop, iow + i);	2051	ev_io_start (loop, iow + i);
1983	}	2052	}
1984	}	2053	}
1985		2054
1986	// stop all watchers after blocking	2055	// stop all watchers after blocking
1987	static void	2056	static void
1988	adns_check_cb (ev_loop loop, ev_check w, int revents)	2057	adns_check_cb (ev_loop loop, ev_check w, int revents)
1989	{	2058	{
1990	ev_timer_stop (loop, &tw);	2059	ev_timer_stop (loop, &tw);
1991		2060
1992	for (int i = 0; i < nfd; ++i)	2061	for (int i = 0; i < nfd; ++i)
1993	{	2062	{
1994	// set the relevant poll flags	2063	// set the relevant poll flags
1995	// could also call adns_processreadable etc. here	2064	// could also call adns_processreadable etc. here
1996	struct pollfd *fd = fds + i;	2065	struct pollfd *fd = fds + i;
1997	int revents = ev_clear_pending (iow + i);	2066	int revents = ev_clear_pending (iow + i);
1998	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;	2067	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1999	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;	2068	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
2000		2069
2001	// now stop the watcher	2070	// now stop the watcher
2002	ev_io_stop (loop, iow + i);	2071	ev_io_stop (loop, iow + i);
2003	}	2072	}
2004		2073
2005	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2074	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
2006	}	2075	}
2007		2076
2008	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2077	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
2009	in the prepare watcher and would dispose of the check watcher.	2078	in the prepare watcher and would dispose of the check watcher.
2010		2079
2011	Method 3: If the module to be embedded supports explicit event	2080	Method 3: If the module to be embedded supports explicit event
2012	notification (libadns does), you can also make use of the actual watcher	2081	notification (libadns does), you can also make use of the actual watcher
2013	callbacks, and only destroy/create the watchers in the prepare watcher.	2082	callbacks, and only destroy/create the watchers in the prepare watcher.
2014		2083
2015	static void	2084	static void
2016	timer_cb (EV_P_ ev_timer *w, int revents)	2085	timer_cb (EV_P_ ev_timer *w, int revents)
2017	{	2086	{
2018	adns_state ads = (adns_state)w->data;	2087	adns_state ads = (adns_state)w->data;
2019	update_now (EV_A);	2088	update_now (EV_A);
2020		2089
2021	adns_processtimeouts (ads, &tv_now);	2090	adns_processtimeouts (ads, &tv_now);
2022	}	2091	}
2023		2092
2024	static void	2093	static void
2025	io_cb (EV_P_ ev_io *w, int revents)	2094	io_cb (EV_P_ ev_io *w, int revents)
2026	{	2095	{
2027	adns_state ads = (adns_state)w->data;	2096	adns_state ads = (adns_state)w->data;
2028	update_now (EV_A);	2097	update_now (EV_A);
2029		2098
2030	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2099	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
2031	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2100	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
2032	}	2101	}
2033		2102
2034	// do not ever call adns_afterpoll	2103	// do not ever call adns_afterpoll
2035		2104
2036	Method 4: Do not use a prepare or check watcher because the module you	2105	Method 4: Do not use a prepare or check watcher because the module you
2037	want to embed is too inflexible to support it. Instead, you can override	2106	want to embed is too inflexible to support it. Instead, you can override
2038	their poll function. The drawback with this solution is that the main	2107	their poll function. The drawback with this solution is that the main
2039	loop is now no longer controllable by EV. The C<Glib::EV> module does	2108	loop is now no longer controllable by EV. The C<Glib::EV> module does
2040	this.	2109	this.
2041		2110
2042	static gint	2111	static gint
2043	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2112	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
2044	{	2113	{
2045	int got_events = 0;	2114	int got_events = 0;
2046		2115
2047	for (n = 0; n < nfds; ++n)	2116	for (n = 0; n < nfds; ++n)
2048	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2117	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
2049		2118
2050	if (timeout >= 0)	2119	if (timeout >= 0)
2051	// create/start timer	2120	// create/start timer
2052		2121
2053	// poll	2122	// poll
2054	ev_loop (EV_A_ 0);	2123	ev_loop (EV_A_ 0);
2055		2124
2056	// stop timer again	2125	// stop timer again
2057	if (timeout >= 0)	2126	if (timeout >= 0)
2058	ev_timer_stop (EV_A_ &to);	2127	ev_timer_stop (EV_A_ &to);
2059		2128
2060	// stop io watchers again - their callbacks should have set	2129	// stop io watchers again - their callbacks should have set
2061	for (n = 0; n < nfds; ++n)	2130	for (n = 0; n < nfds; ++n)
2062	ev_io_stop (EV_A_ iow [n]);	2131	ev_io_stop (EV_A_ iow [n]);
2063		2132
2064	return got_events;	2133	return got_events;
2065	}	2134	}
2066		2135
2067		2136
2068	=head2 C<ev_embed> - when one backend isn't enough...	2137	=head2 C<ev_embed> - when one backend isn't enough...
2069		2138
2070	This is a rather advanced watcher type that lets you embed one event loop	2139	This is a rather advanced watcher type that lets you embed one event loop
…		…
2148	event loop. If that is not possible, use the default loop. The default	2217	event loop. If that is not possible, use the default loop. The default
2149	loop is stored in C<loop_hi>, while the embeddable loop is stored in	2218	loop is stored in C<loop_hi>, while the embeddable loop is stored in
2150	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be	2219	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2151	used).	2220	used).
2152		2221
2153	struct ev_loop *loop_hi = ev_default_init (0);	2222	struct ev_loop *loop_hi = ev_default_init (0);
2154	struct ev_loop *loop_lo = 0;	2223	struct ev_loop *loop_lo = 0;
2155	struct ev_embed embed;	2224	struct ev_embed embed;
2156		2225
2157	// see if there is a chance of getting one that works	2226	// see if there is a chance of getting one that works
2158	// (remember that a flags value of 0 means autodetection)	2227	// (remember that a flags value of 0 means autodetection)
2159	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2228	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2160	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2229	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2161	: 0;	2230	: 0;
2162		2231
2163	// if we got one, then embed it, otherwise default to loop_hi	2232	// if we got one, then embed it, otherwise default to loop_hi
2164	if (loop_lo)	2233	if (loop_lo)
2165	{	2234	{
2166	ev_embed_init (&embed, 0, loop_lo);	2235	ev_embed_init (&embed, 0, loop_lo);
2167	ev_embed_start (loop_hi, &embed);	2236	ev_embed_start (loop_hi, &embed);
2168	}	2237	}
2169	else	2238	else
2170	loop_lo = loop_hi;	2239	loop_lo = loop_hi;
2171		2240
2172	Example: Check if kqueue is available but not recommended and create	2241	Example: Check if kqueue is available but not recommended and create
2173	a kqueue backend for use with sockets (which usually work with any	2242	a kqueue backend for use with sockets (which usually work with any
2174	kqueue implementation). Store the kqueue/socket-only event loop in	2243	kqueue implementation). Store the kqueue/socket-only event loop in
2175	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2244	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2176		2245
2177	struct ev_loop *loop = ev_default_init (0);	2246	struct ev_loop *loop = ev_default_init (0);
2178	struct ev_loop *loop_socket = 0;	2247	struct ev_loop *loop_socket = 0;
2179	struct ev_embed embed;	2248	struct ev_embed embed;
2180		2249
2181	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2250	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2182	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2251	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2183	{	2252	{
2184	ev_embed_init (&embed, 0, loop_socket);	2253	ev_embed_init (&embed, 0, loop_socket);
2185	ev_embed_start (loop, &embed);	2254	ev_embed_start (loop, &embed);
2186	}	2255	}
2187		2256
2188	if (!loop_socket)	2257	if (!loop_socket)
2189	loop_socket = loop;	2258	loop_socket = loop;
2190		2259
2191	// now use loop_socket for all sockets, and loop for everything else	2260	// now use loop_socket for all sockets, and loop for everything else
2192		2261
2193		2262
2194	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2263	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2195		2264
2196	Fork watchers are called when a C<fork ()> was detected (usually because	2265	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2385	The callback has the type C<void (cb)(int revents, void arg)> and gets	2454	The callback has the type C<void (cb)(int revents, void arg)> and gets
2386	passed an C<revents> set like normal event callbacks (a combination of	2455	passed an C<revents> set like normal event callbacks (a combination of
2387	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2456	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2388	value passed to C<ev_once>:	2457	value passed to C<ev_once>:
2389		2458
2390	static void stdin_ready (int revents, void *arg)	2459	static void stdin_ready (int revents, void *arg)
2391	{	2460	{
2392	if (revents & EV_TIMEOUT)	2461	if (revents & EV_TIMEOUT)
2393	/* doh, nothing entered */;	2462	/* doh, nothing entered */;
2394	else if (revents & EV_READ)	2463	else if (revents & EV_READ)
2395	/* stdin might have data for us, joy! */;	2464	/* stdin might have data for us, joy! */;
2396	}	2465	}
2397		2466
2398	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2467	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2399		2468
2400	=item ev_feed_event (ev_loop , watcher , int revents)	2469	=item ev_feed_event (ev_loop , watcher , int revents)
2401		2470
2402	Feeds the given event set into the event loop, as if the specified event	2471	Feeds the given event set into the event loop, as if the specified event
2403	had happened for the specified watcher (which must be a pointer to an	2472	had happened for the specified watcher (which must be a pointer to an
…		…
2452	you to use some convenience methods to start/stop watchers and also change	2521	you to use some convenience methods to start/stop watchers and also change
2453	the callback model to a model using method callbacks on objects.	2522	the callback model to a model using method callbacks on objects.
2454		2523
2455	To use it,	2524	To use it,
2456		2525
2457	#include <ev++.h>	2526	#include <ev++.h>
2458		2527
2459	This automatically includes F<ev.h> and puts all of its definitions (many	2528	This automatically includes F<ev.h> and puts all of its definitions (many
2460	of them macros) into the global namespace. All C++ specific things are	2529	of them macros) into the global namespace. All C++ specific things are
2461	put into the C<ev> namespace. It should support all the same embedding	2530	put into the C<ev> namespace. It should support all the same embedding
2462	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2531	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2529	your compiler is good :), then the method will be fully inlined into the	2598	your compiler is good :), then the method will be fully inlined into the
2530	thunking function, making it as fast as a direct C callback.	2599	thunking function, making it as fast as a direct C callback.
2531		2600
2532	Example: simple class declaration and watcher initialisation	2601	Example: simple class declaration and watcher initialisation
2533		2602
2534	struct myclass	2603	struct myclass
2535	{	2604	{
2536	void io_cb (ev::io &w, int revents) { }	2605	void io_cb (ev::io &w, int revents) { }
2537	}	2606	}
2538		2607
2539	myclass obj;	2608	myclass obj;
2540	ev::io iow;	2609	ev::io iow;
2541	iow.set <myclass, &myclass::io_cb> (&obj);	2610	iow.set <myclass, &myclass::io_cb> (&obj);
2542		2611
2543	=item w->set<function> (void *data = 0)	2612	=item w->set<function> (void *data = 0)
2544		2613
2545	Also sets a callback, but uses a static method or plain function as	2614	Also sets a callback, but uses a static method or plain function as
2546	callback. The optional C<data> argument will be stored in the watcher's	2615	callback. The optional C<data> argument will be stored in the watcher's
…		…
2550		2619
2551	See the method-C<set> above for more details.	2620	See the method-C<set> above for more details.
2552		2621
2553	Example:	2622	Example:
2554		2623
2555	static void io_cb (ev::io &w, int revents) { }	2624	static void io_cb (ev::io &w, int revents) { }
2556	iow.set <io_cb> ();	2625	iow.set <io_cb> ();
2557		2626
2558	=item w->set (struct ev_loop *)	2627	=item w->set (struct ev_loop *)
2559		2628
2560	Associates a different C<struct ev_loop> with this watcher. You can only	2629	Associates a different C<struct ev_loop> with this watcher. You can only
2561	do this when the watcher is inactive (and not pending either).	2630	do this when the watcher is inactive (and not pending either).
…		…
2594	=back	2663	=back
2595		2664
2596	Example: Define a class with an IO and idle watcher, start one of them in	2665	Example: Define a class with an IO and idle watcher, start one of them in
2597	the constructor.	2666	the constructor.
2598		2667
2599	class myclass	2668	class myclass
2600	{	2669	{
2601	ev::io io; void io_cb (ev::io &w, int revents);	2670	ev::io io; void io_cb (ev::io &w, int revents);
2602	ev:idle idle void idle_cb (ev::idle &w, int revents);	2671	ev:idle idle void idle_cb (ev::idle &w, int revents);
2603		2672
2604	myclass (int fd)	2673	myclass (int fd)
2605	{	2674	{
2606	io .set <myclass, &myclass::io_cb > (this);	2675	io .set <myclass, &myclass::io_cb > (this);
2607	idle.set <myclass, &myclass::idle_cb> (this);	2676	idle.set <myclass, &myclass::idle_cb> (this);
2608		2677
2609	io.start (fd, ev::READ);	2678	io.start (fd, ev::READ);
2610	}	2679	}
2611	};	2680	};
2612		2681
2613		2682
2614	=head1 OTHER LANGUAGE BINDINGS	2683	=head1 OTHER LANGUAGE BINDINGS
2615		2684
2616	Libev does not offer other language bindings itself, but bindings for a	2685	Libev does not offer other language bindings itself, but bindings for a
…		…
2626	libev. EV is developed together with libev. Apart from the EV core module,	2695	libev. EV is developed together with libev. Apart from the EV core module,
2627	there are additional modules that implement libev-compatible interfaces	2696	there are additional modules that implement libev-compatible interfaces
2628	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the	2697	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
2629	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).	2698	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2630		2699
2631	It can be found and installed via CPAN, its homepage is found at	2700	It can be found and installed via CPAN, its homepage is at
2632	L<http://software.schmorp.de/pkg/EV>.	2701	L<http://software.schmorp.de/pkg/EV>.
		2702
		2703	=item Python
		2704
		2705	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2706	seems to be quite complete and well-documented. Note, however, that the
		2707	patch they require for libev is outright dangerous as it breaks the ABI
		2708	for everybody else, and therefore, should never be applied in an installed
		2709	libev (if python requires an incompatible ABI then it needs to embed
		2710	libev).
2633		2711
2634	=item Ruby	2712	=item Ruby
2635		2713
2636	Tony Arcieri has written a ruby extension that offers access to a subset	2714	Tony Arcieri has written a ruby extension that offers access to a subset
2637	of the libev API and adds file handle abstractions, asynchronous DNS and	2715	of the libev API and adds file handle abstractions, asynchronous DNS and
…		…
2639	L<http://rev.rubyforge.org/>.	2717	L<http://rev.rubyforge.org/>.
2640		2718
2641	=item D	2719	=item D
2642		2720
2643	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	2721	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
2644	be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.	2722	be found at L<http://proj.llucax.com.ar/wiki/evd>.
2645		2723
2646	=back	2724	=back
2647		2725
2648		2726
2649	=head1 MACRO MAGIC	2727	=head1 MACRO MAGIC
…		…
2661		2739
2662	This provides the loop I<argument> for functions, if one is required ("ev	2740	This provides the loop I<argument> for functions, if one is required ("ev
2663	loop argument"). The C<EV_A> form is used when this is the sole argument,	2741	loop argument"). The C<EV_A> form is used when this is the sole argument,
2664	C<EV_A_> is used when other arguments are following. Example:	2742	C<EV_A_> is used when other arguments are following. Example:
2665		2743
2666	ev_unref (EV_A);	2744	ev_unref (EV_A);
2667	ev_timer_add (EV_A_ watcher);	2745	ev_timer_add (EV_A_ watcher);
2668	ev_loop (EV_A_ 0);	2746	ev_loop (EV_A_ 0);
2669		2747
2670	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2748	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2671	which is often provided by the following macro.	2749	which is often provided by the following macro.
2672		2750
2673	=item C<EV_P>, C<EV_P_>	2751	=item C<EV_P>, C<EV_P_>
2674		2752
2675	This provides the loop I<parameter> for functions, if one is required ("ev	2753	This provides the loop I<parameter> for functions, if one is required ("ev
2676	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2754	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2677	C<EV_P_> is used when other parameters are following. Example:	2755	C<EV_P_> is used when other parameters are following. Example:
2678		2756
2679	// this is how ev_unref is being declared	2757	// this is how ev_unref is being declared
2680	static void ev_unref (EV_P);	2758	static void ev_unref (EV_P);
2681		2759
2682	// this is how you can declare your typical callback	2760	// this is how you can declare your typical callback
2683	static void cb (EV_P_ ev_timer *w, int revents)	2761	static void cb (EV_P_ ev_timer *w, int revents)
2684		2762
2685	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2763	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2686	suitable for use with C<EV_A>.	2764	suitable for use with C<EV_A>.
2687		2765
2688	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2766	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
…		…
2704		2782
2705	Example: Declare and initialise a check watcher, utilising the above	2783	Example: Declare and initialise a check watcher, utilising the above
2706	macros so it will work regardless of whether multiple loops are supported	2784	macros so it will work regardless of whether multiple loops are supported
2707	or not.	2785	or not.
2708		2786
2709	static void	2787	static void
2710	check_cb (EV_P_ ev_timer *w, int revents)	2788	check_cb (EV_P_ ev_timer *w, int revents)
2711	{	2789	{
2712	ev_check_stop (EV_A_ w);	2790	ev_check_stop (EV_A_ w);
2713	}	2791	}
2714		2792
2715	ev_check check;	2793	ev_check check;
2716	ev_check_init (&check, check_cb);	2794	ev_check_init (&check, check_cb);
2717	ev_check_start (EV_DEFAULT_ &check);	2795	ev_check_start (EV_DEFAULT_ &check);
2718	ev_loop (EV_DEFAULT_ 0);	2796	ev_loop (EV_DEFAULT_ 0);
2719		2797
2720	=head1 EMBEDDING	2798	=head1 EMBEDDING
2721		2799
2722	Libev can (and often is) directly embedded into host	2800	Libev can (and often is) directly embedded into host
2723	applications. Examples of applications that embed it include the Deliantra	2801	applications. Examples of applications that embed it include the Deliantra
…		…
2737	=head3 CORE EVENT LOOP	2815	=head3 CORE EVENT LOOP
2738		2816
2739	To include only the libev core (all the C<ev_*> functions), with manual	2817	To include only the libev core (all the C<ev_*> functions), with manual
2740	configuration (no autoconf):	2818	configuration (no autoconf):
2741		2819
2742	#define EV_STANDALONE 1	2820	#define EV_STANDALONE 1
2743	#include "ev.c"	2821	#include "ev.c"
2744		2822
2745	This will automatically include F<ev.h>, too, and should be done in a	2823	This will automatically include F<ev.h>, too, and should be done in a
2746	single C source file only to provide the function implementations. To use	2824	single C source file only to provide the function implementations. To use
2747	it, do the same for F<ev.h> in all files wishing to use this API (best	2825	it, do the same for F<ev.h> in all files wishing to use this API (best
2748	done by writing a wrapper around F<ev.h> that you can include instead and	2826	done by writing a wrapper around F<ev.h> that you can include instead and
2749	where you can put other configuration options):	2827	where you can put other configuration options):
2750		2828
2751	#define EV_STANDALONE 1	2829	#define EV_STANDALONE 1
2752	#include "ev.h"	2830	#include "ev.h"
2753		2831
2754	Both header files and implementation files can be compiled with a C++	2832	Both header files and implementation files can be compiled with a C++
2755	compiler (at least, thats a stated goal, and breakage will be treated	2833	compiler (at least, thats a stated goal, and breakage will be treated
2756	as a bug).	2834	as a bug).
2757		2835
2758	You need the following files in your source tree, or in a directory	2836	You need the following files in your source tree, or in a directory
2759	in your include path (e.g. in libev/ when using -Ilibev):	2837	in your include path (e.g. in libev/ when using -Ilibev):
2760		2838
2761	ev.h	2839	ev.h
2762	ev.c	2840	ev.c
2763	ev_vars.h	2841	ev_vars.h
2764	ev_wrap.h	2842	ev_wrap.h
2765		2843
2766	ev_win32.c required on win32 platforms only	2844	ev_win32.c required on win32 platforms only
2767		2845
2768	ev_select.c only when select backend is enabled (which is enabled by default)	2846	ev_select.c only when select backend is enabled (which is enabled by default)
2769	ev_poll.c only when poll backend is enabled (disabled by default)	2847	ev_poll.c only when poll backend is enabled (disabled by default)
2770	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2848	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2771	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2849	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2772	ev_port.c only when the solaris port backend is enabled (disabled by default)	2850	ev_port.c only when the solaris port backend is enabled (disabled by default)
2773		2851
2774	F<ev.c> includes the backend files directly when enabled, so you only need	2852	F<ev.c> includes the backend files directly when enabled, so you only need
2775	to compile this single file.	2853	to compile this single file.
2776		2854
2777	=head3 LIBEVENT COMPATIBILITY API	2855	=head3 LIBEVENT COMPATIBILITY API
2778		2856
2779	To include the libevent compatibility API, also include:	2857	To include the libevent compatibility API, also include:
2780		2858
2781	#include "event.c"	2859	#include "event.c"
2782		2860
2783	in the file including F<ev.c>, and:	2861	in the file including F<ev.c>, and:
2784		2862
2785	#include "event.h"	2863	#include "event.h"
2786		2864
2787	in the files that want to use the libevent API. This also includes F<ev.h>.	2865	in the files that want to use the libevent API. This also includes F<ev.h>.
2788		2866
2789	You need the following additional files for this:	2867	You need the following additional files for this:
2790		2868
2791	event.h	2869	event.h
2792	event.c	2870	event.c
2793		2871
2794	=head3 AUTOCONF SUPPORT	2872	=head3 AUTOCONF SUPPORT
2795		2873
2796	Instead of using C<EV_STANDALONE=1> and providing your configuration in	2874	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2797	whatever way you want, you can also C<m4_include([libev.m4])> in your	2875	whatever way you want, you can also C<m4_include([libev.m4])> in your
2798	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2876	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2799	include F<config.h> and configure itself accordingly.	2877	include F<config.h> and configure itself accordingly.
2800		2878
2801	For this of course you need the m4 file:	2879	For this of course you need the m4 file:
2802		2880
2803	libev.m4	2881	libev.m4
2804		2882
2805	=head2 PREPROCESSOR SYMBOLS/MACROS	2883	=head2 PREPROCESSOR SYMBOLS/MACROS
2806		2884
2807	Libev can be configured via a variety of preprocessor symbols you have to	2885	Libev can be configured via a variety of preprocessor symbols you have to
2808	define before including any of its files. The default in the absence of	2886	define before including any of its files. The default in the absence of
…		…
3085	members. You have to define it each time you include one of the files,	3163	members. You have to define it each time you include one of the files,
3086	though, and it must be identical each time.	3164	though, and it must be identical each time.
3087		3165
3088	For example, the perl EV module uses something like this:	3166	For example, the perl EV module uses something like this:
3089		3167
3090	#define EV_COMMON \	3168	#define EV_COMMON \
3091	SV self; / contains this struct */ \	3169	SV self; / contains this struct */ \
3092	SV cb_sv, fh /* note no trailing ";" */	3170	SV cb_sv, fh /* note no trailing ";" */
3093		3171
3094	=item EV_CB_DECLARE (type)	3172	=item EV_CB_DECLARE (type)
3095		3173
3096	=item EV_CB_INVOKE (watcher, revents)	3174	=item EV_CB_INVOKE (watcher, revents)
3097		3175
…		…
3108		3186
3109	If you need to re-export the API (e.g. via a DLL) and you need a list of	3187	If you need to re-export the API (e.g. via a DLL) and you need a list of
3110	exported symbols, you can use the provided F<Symbol.*> files which list	3188	exported symbols, you can use the provided F<Symbol.*> files which list
3111	all public symbols, one per line:	3189	all public symbols, one per line:
3112		3190
3113	Symbols.ev for libev proper	3191	Symbols.ev for libev proper
3114	Symbols.event for the libevent emulation	3192	Symbols.event for the libevent emulation
3115		3193
3116	This can also be used to rename all public symbols to avoid clashes with	3194	This can also be used to rename all public symbols to avoid clashes with
3117	multiple versions of libev linked together (which is obviously bad in	3195	multiple versions of libev linked together (which is obviously bad in
3118	itself, but sometimes it is inconvenient to avoid this).	3196	itself, but sometimes it is inconvenient to avoid this).
3119		3197
…		…
3140	file.	3218	file.
3141		3219
3142	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3220	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3143	that everybody includes and which overrides some configure choices:	3221	that everybody includes and which overrides some configure choices:
3144		3222
3145	#define EV_MINIMAL 1	3223	#define EV_MINIMAL 1
3146	#define EV_USE_POLL 0	3224	#define EV_USE_POLL 0
3147	#define EV_MULTIPLICITY 0	3225	#define EV_MULTIPLICITY 0
3148	#define EV_PERIODIC_ENABLE 0	3226	#define EV_PERIODIC_ENABLE 0
3149	#define EV_STAT_ENABLE 0	3227	#define EV_STAT_ENABLE 0
3150	#define EV_FORK_ENABLE 0	3228	#define EV_FORK_ENABLE 0
3151	#define EV_CONFIG_H <config.h>	3229	#define EV_CONFIG_H <config.h>
3152	#define EV_MINPRI 0	3230	#define EV_MINPRI 0
3153	#define EV_MAXPRI 0	3231	#define EV_MAXPRI 0
3154		3232
3155	#include "ev++.h"	3233	#include "ev++.h"
3156		3234
3157	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3235	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3158		3236
3159	#include "ev_cpp.h"	3237	#include "ev_cpp.h"
3160	#include "ev.c"	3238	#include "ev.c"
3161		3239
3162		3240
3163	=head1 THREADS AND COROUTINES	3241	=head1 THREADS AND COROUTINES
3164		3242
3165	=head2 THREADS	3243	=head2 THREADS
…		…
3173	parallel from multiple threads, calls with the same loop parameter must be	3251	parallel from multiple threads, calls with the same loop parameter must be
3174	done serially (but can be done from different threads, as long as only one	3252	done serially (but can be done from different threads, as long as only one
3175	thread ever is inside a call at any point in time, e.g. by using a mutex	3253	thread ever is inside a call at any point in time, e.g. by using a mutex
3176	per loop).	3254	per loop).
3177		3255
3178	If you want to know which design is best for your problem, then I cannot	3256	If you want to know which design (one loop, locking, or multiple loops
3179	help you but by giving some generic advice:	3257	without or something else still) is best for your problem, then I cannot
		3258	help you. I can give some generic advice however:
3180		3259
3181	=over 4	3260	=over 4
3182		3261
3183	=item * most applications have a main thread: use the default libev loop	3262	=item * most applications have a main thread: use the default libev loop
3184	in that thread, or create a separate thread running only the default loop.	3263	in that thread, or create a separate thread running only the default loop.
…		…
3317	more than a hundred or so sockets, then likely it needs to use a totally	3396	more than a hundred or so sockets, then likely it needs to use a totally
3318	different implementation for windows, as libev offers the POSIX readiness	3397	different implementation for windows, as libev offers the POSIX readiness
3319	notification model, which cannot be implemented efficiently on windows	3398	notification model, which cannot be implemented efficiently on windows
3320	(Microsoft monopoly games).	3399	(Microsoft monopoly games).
3321		3400
		3401	A typical way to use libev under windows is to embed it (see the embedding
		3402	section for details) and use the following F<evwrap.h> header file instead
		3403	of F<ev.h>:
		3404
		3405	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3406	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3407
		3408	#include "ev.h"
		3409
		3410	And compile the following F<evwrap.c> file into your project (make sure
		3411	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3412
		3413	#include "evwrap.h"
		3414	#include "ev.c"
		3415
3322	=over 4	3416	=over 4
3323		3417
3324	=item The winsocket select function	3418	=item The winsocket select function
3325		3419
3326	The winsocket C<select> function doesn't follow POSIX in that it	3420	The winsocket C<select> function doesn't follow POSIX in that it
3327	requires socket I<handles> and not socket I<file descriptors> (it is	3421	requires socket I<handles> and not socket I<file descriptors> (it is
3328	also extremely buggy). This makes select very inefficient, and also	3422	also extremely buggy). This makes select very inefficient, and also
3329	requires a mapping from file descriptors to socket handles. See the	3423	requires a mapping from file descriptors to socket handles (the Microsoft
		3424	C runtime provides the function C<_open_osfhandle> for this). See the
3330	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and	3425	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
3331	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.	3426	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3332		3427
3333	The configuration for a "naked" win32 using the Microsoft runtime	3428	The configuration for a "naked" win32 using the Microsoft runtime
3334	libraries and raw winsocket select is:	3429	libraries and raw winsocket select is:
3335		3430
3336	#define EV_USE_SELECT 1	3431	#define EV_USE_SELECT 1
3337	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3432	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3338		3433
3339	Note that winsockets handling of fd sets is O(n), so you can easily get a	3434	Note that winsockets handling of fd sets is O(n), so you can easily get a
3340	complexity in the O(n²) range when using win32.	3435	complexity in the O(n²) range when using win32.
3341		3436
3342	=item Limited number of file descriptors	3437	=item Limited number of file descriptors
…		…
3374	In addition to a working ISO-C implementation, libev relies on a few	3469	In addition to a working ISO-C implementation, libev relies on a few
3375	additional extensions:	3470	additional extensions:
3376		3471
3377	=over 4	3472	=over 4
3378		3473
		3474	=item C<void ()(ev_watcher_type , int revents)> must have compatible
		3475	calling conventions regardless of C<ev_watcher_type *>.
		3476
		3477	Libev assumes not only that all watcher pointers have the same internal
		3478	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3479	assumes that the same (machine) code can be used to call any watcher
		3480	callback: The watcher callbacks have different type signatures, but libev
		3481	calls them using an C<ev_watcher *> internally.
		3482
3379	=item C<sig_atomic_t volatile> must be thread-atomic as well	3483	=item C<sig_atomic_t volatile> must be thread-atomic as well
3380		3484
3381	The type C<sig_atomic_t volatile> (or whatever is defined as	3485	The type C<sig_atomic_t volatile> (or whatever is defined as
3382	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different	3486	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
3383	threads. This is not part of the specification for C<sig_atomic_t>, but is	3487	threads. This is not part of the specification for C<sig_atomic_t>, but is

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