[ViewVC] Diff of: cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.36 by root, Sat Nov 24 07:14:26 2007 UTC vs.
Revision 1.53 by root, Tue Nov 27 20:15:02 2007 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	/* this is the only header you need */
7	#include <ev.h>	8	#include <ev.h>
		9
		10	/* what follows is a fully working example program */
		11	ev_io stdin_watcher;
		12	ev_timer timeout_watcher;
		13
		14	/* called when data readable on stdin */
		15	static void
		16	stdin_cb (EV_P_ struct ev_io *w, int revents)
		17	{
		18	/* puts ("stdin ready"); */
		19	ev_io_stop (EV_A_ w); /* just a syntax example */
		20	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
		21	}
		22
		23	static void
		24	timeout_cb (EV_P_ struct ev_timer *w, int revents)
		25	{
		26	/* puts ("timeout"); */
		27	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
		28	}
		29
		30	int
		31	main (void)
		32	{
		33	struct ev_loop *loop = ev_default_loop (0);
		34
		35	/* initialise an io watcher, then start it */
		36	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);
		37	ev_io_start (loop, &stdin_watcher);
		38
		39	/* simple non-repeating 5.5 second timeout */
		40	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		41	ev_timer_start (loop, &timeout_watcher);
		42
		43	/* loop till timeout or data ready */
		44	ev_loop (loop, 0);
		45
		46	return 0;
		47	}
8		48
9	=head1 DESCRIPTION	49	=head1 DESCRIPTION
10		50
11	Libev is an event loop: you register interest in certain events (such as a	51	Libev is an event loop: you register interest in certain events (such as a
12	file descriptor being readable or a timeout occuring), and it will manage	52	file descriptor being readable or a timeout occuring), and it will manage
…		…
48	the beginning of 1970, details are complicated, don't ask). This type is	88	the beginning of 1970, details are complicated, don't ask). This type is
49	called C<ev_tstamp>, which is what you should use too. It usually aliases	89	called C<ev_tstamp>, which is what you should use too. It usually aliases
50	to the C<double> type in C, and when you need to do any calculations on	90	to the C<double> type in C, and when you need to do any calculations on
51	it, you should treat it as such.	91	it, you should treat it as such.
52		92
53
54	=head1 GLOBAL FUNCTIONS	93	=head1 GLOBAL FUNCTIONS
55		94
56	These functions can be called anytime, even before initialising the	95	These functions can be called anytime, even before initialising the
57	library in any way.	96	library in any way.
58		97
…		…
116	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	155	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
117	recommended ones.	156	recommended ones.
118		157
119	See the description of C<ev_embed> watchers for more info.	158	See the description of C<ev_embed> watchers for more info.
120		159
121	=item ev_set_allocator (void (cb)(void *ptr, long size))	160	=item ev_set_allocator (void (cb)(void *ptr, size_t size))
122		161
123	Sets the allocation function to use (the prototype is similar to the	162	Sets the allocation function to use (the prototype and semantics are
124	realloc C function, the semantics are identical). It is used to allocate	163	identical to the realloc C function). It is used to allocate and free
125	and free memory (no surprises here). If it returns zero when memory	164	memory (no surprises here). If it returns zero when memory needs to be
126	needs to be allocated, the library might abort or take some potentially	165	allocated, the library might abort or take some potentially destructive
127	destructive action. The default is your system realloc function.	166	action. The default is your system realloc function.
128		167
129	You could override this function in high-availability programs to, say,	168	You could override this function in high-availability programs to, say,
130	free some memory if it cannot allocate memory, to use a special allocator,	169	free some memory if it cannot allocate memory, to use a special allocator,
131	or even to sleep a while and retry until some memory is available.	170	or even to sleep a while and retry until some memory is available.
132		171
133	Example: replace the libev allocator with one that waits a bit and then	172	Example: replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	173	retries: better than mine).
135		174
136	static void *	175	static void *
137	persistent_realloc (void *ptr, long size)	176	persistent_realloc (void *ptr, size_t size)
138	{	177	{
139	for (;;)	178	for (;;)
140	{	179	{
141	void *newptr = realloc (ptr, size);	180	void *newptr = realloc (ptr, size);
142		181
…		…
323	fatal ("no epoll found here, maybe it hides under your chair");	362	fatal ("no epoll found here, maybe it hides under your chair");
324		363
325	=item ev_default_destroy ()	364	=item ev_default_destroy ()
326		365
327	Destroys the default loop again (frees all memory and kernel state	366	Destroys the default loop again (frees all memory and kernel state
328	etc.). This stops all registered event watchers (by not touching them in	367	etc.). None of the active event watchers will be stopped in the normal
329	any way whatsoever, although you cannot rely on this :).	368	sense, so e.g. C<ev_is_active> might still return true. It is your
		369	responsibility to either stop all watchers cleanly yoursef I<before>
		370	calling this function, or cope with the fact afterwards (which is usually
		371	the easiest thing, youc na just ignore the watchers and/or C<free ()> them
		372	for example).
330		373
331	=item ev_loop_destroy (loop)	374	=item ev_loop_destroy (loop)
332		375
333	Like C<ev_default_destroy>, but destroys an event loop created by an	376	Like C<ev_default_destroy>, but destroys an event loop created by an
334	earlier call to C<ev_loop_new>.	377	earlier call to C<ev_loop_new>.
…		…
464	ev_ref (myloop);	507	ev_ref (myloop);
465	ev_signal_stop (myloop, &exitsig);	508	ev_signal_stop (myloop, &exitsig);
466		509
467	=back	510	=back
468		511
		512
469	=head1 ANATOMY OF A WATCHER	513	=head1 ANATOMY OF A WATCHER
470		514
471	A watcher is a structure that you create and register to record your	515	A watcher is a structure that you create and register to record your
472	interest in some event. For instance, if you want to wait for STDIN to	516	interest in some event. For instance, if you want to wait for STDIN to
473	become readable, you would create an C<ev_io> watcher for that:	517	become readable, you would create an C<ev_io> watcher for that:
…		…
539	The signal specified in the C<ev_signal> watcher has been received by a thread.	583	The signal specified in the C<ev_signal> watcher has been received by a thread.
540		584
541	=item C<EV_CHILD>	585	=item C<EV_CHILD>
542		586
543	The pid specified in the C<ev_child> watcher has received a status change.	587	The pid specified in the C<ev_child> watcher has received a status change.
		588
		589	=item C<EV_STAT>
		590
		591	The path specified in the C<ev_stat> watcher changed its attributes somehow.
544		592
545	=item C<EV_IDLE>	593	=item C<EV_IDLE>
546		594
547	The C<ev_idle> watcher has determined that you have nothing better to do.	595	The C<ev_idle> watcher has determined that you have nothing better to do.
548		596
…		…
556	received events. Callbacks of both watcher types can start and stop as	604	received events. Callbacks of both watcher types can start and stop as
557	many watchers as they want, and all of them will be taken into account	605	many watchers as they want, and all of them will be taken into account
558	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	606	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
559	C<ev_loop> from blocking).	607	C<ev_loop> from blocking).
560		608
		609	=item C<EV_EMBED>
		610
		611	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		612
		613	=item C<EV_FORK>
		614
		615	The event loop has been resumed in the child process after fork (see
		616	C<ev_fork>).
		617
561	=item C<EV_ERROR>	618	=item C<EV_ERROR>
562		619
563	An unspecified error has occured, the watcher has been stopped. This might	620	An unspecified error has occured, the watcher has been stopped. This might
564	happen because the watcher could not be properly started because libev	621	happen because the watcher could not be properly started because libev
565	ran out of memory, a file descriptor was found to be closed or any other	622	ran out of memory, a file descriptor was found to be closed or any other
…		…
572	with the error from read() or write(). This will not work in multithreaded	629	with the error from read() or write(). This will not work in multithreaded
573	programs, though, so beware.	630	programs, though, so beware.
574		631
575	=back	632	=back
576		633
577	=head2 SUMMARY OF GENERIC WATCHER FUNCTIONS	634	=head2 GENERIC WATCHER FUNCTIONS
578		635
579	In the following description, C<TYPE> stands for the watcher type,	636	In the following description, C<TYPE> stands for the watcher type,
580	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.	637	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.
581		638
582	=over 4	639	=over 4
…		…
591	which rolls both calls into one.	648	which rolls both calls into one.
592		649
593	You can reinitialise a watcher at any time as long as it has been stopped	650	You can reinitialise a watcher at any time as long as it has been stopped
594	(or never started) and there are no pending events outstanding.	651	(or never started) and there are no pending events outstanding.
595		652
596	The callbakc is always of type C<void ()(ev_loop loop, ev_TYPE *watcher,	653	The callback is always of type C<void ()(ev_loop loop, ev_TYPE *watcher,
597	int revents)>.	654	int revents)>.
598		655
599	=item C<ev_TYPE_set> (ev_TYPE *, [args])	656	=item C<ev_TYPE_set> (ev_TYPE *, [args])
600		657
601	This macro initialises the type-specific parts of a watcher. You need to	658	This macro initialises the type-specific parts of a watcher. You need to
…		…
684		741
685		742
686	=head1 WATCHER TYPES	743	=head1 WATCHER TYPES
687		744
688	This section describes each watcher in detail, but will not repeat	745	This section describes each watcher in detail, but will not repeat
689	information given in the last section.	746	information given in the last section. Any initialisation/set macros,
		747	functions and members specific to the watcher type are explained.
690		748
		749	Members are additionally marked with either I<[read-only]>, meaning that,
		750	while the watcher is active, you can look at the member and expect some
		751	sensible content, but you must not modify it (you can modify it while the
		752	watcher is stopped to your hearts content), or I<[read-write]>, which
		753	means you can expect it to have some sensible content while the watcher
		754	is active, but you can also modify it. Modifying it may not do something
		755	sensible or take immediate effect (or do anything at all), but libev will
		756	not crash or malfunction in any way.
691		757
		758
692	=head2 C<ev_io> - is this file descriptor readable or writable	759	=head2 C<ev_io> - is this file descriptor readable or writable?
693		760
694	I/O watchers check whether a file descriptor is readable or writable	761	I/O watchers check whether a file descriptor is readable or writable
695	in each iteration of the event loop (This behaviour is called	762	in each iteration of the event loop, or, more precisely, when reading
696	level-triggering because you keep receiving events as long as the	763	would not block the process and writing would at least be able to write
697	condition persists. Remember you can stop the watcher if you don't want to	764	some data. This behaviour is called level-triggering because you keep
698	act on the event and neither want to receive future events).	765	receiving events as long as the condition persists. Remember you can stop
		766	the watcher if you don't want to act on the event and neither want to
		767	receive future events.
699		768
700	In general you can register as many read and/or write event watchers per	769	In general you can register as many read and/or write event watchers per
701	fd as you want (as long as you don't confuse yourself). Setting all file	770	fd as you want (as long as you don't confuse yourself). Setting all file
702	descriptors to non-blocking mode is also usually a good idea (but not	771	descriptors to non-blocking mode is also usually a good idea (but not
703	required if you know what you are doing).	772	required if you know what you are doing).
704		773
705	You have to be careful with dup'ed file descriptors, though. Some backends	774	You have to be careful with dup'ed file descriptors, though. Some backends
706	(the linux epoll backend is a notable example) cannot handle dup'ed file	775	(the linux epoll backend is a notable example) cannot handle dup'ed file
707	descriptors correctly if you register interest in two or more fds pointing	776	descriptors correctly if you register interest in two or more fds pointing
708	to the same underlying file/socket etc. description (that is, they share	777	to the same underlying file/socket/etc. description (that is, they share
709	the same underlying "file open").	778	the same underlying "file open").
710		779
711	If you must do this, then force the use of a known-to-be-good backend	780	If you must do this, then force the use of a known-to-be-good backend
712	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	781	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
713	C<EVBACKEND_POLL>).	782	C<EVBACKEND_POLL>).
714		783
		784	Another thing you have to watch out for is that it is quite easy to
		785	receive "spurious" readyness notifications, that is your callback might
		786	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
		787	because there is no data. Not only are some backends known to create a
		788	lot of those (for example solaris ports), it is very easy to get into
		789	this situation even with a relatively standard program structure. Thus
		790	it is best to always use non-blocking I/O: An extra C<read>(2) returning
		791	C<EAGAIN> is far preferable to a program hanging until some data arrives.
		792
		793	If you cannot run the fd in non-blocking mode (for example you should not
		794	play around with an Xlib connection), then you have to seperately re-test
		795	wether a file descriptor is really ready with a known-to-be good interface
		796	such as poll (fortunately in our Xlib example, Xlib already does this on
		797	its own, so its quite safe to use).
		798
715	=over 4	799	=over 4
716		800
717	=item ev_io_init (ev_io *, callback, int fd, int events)	801	=item ev_io_init (ev_io *, callback, int fd, int events)
718		802
719	=item ev_io_set (ev_io *, int fd, int events)	803	=item ev_io_set (ev_io *, int fd, int events)
720		804
721	Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive	805	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
722	events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ \|	806	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
723	EV_WRITE> to receive the given events.	807	C<EV_READ \| EV_WRITE> to receive the given events.
724		808
725	Please note that most of the more scalable backend mechanisms (for example	809	=item int fd [read-only]
726	epoll and solaris ports) can result in spurious readyness notifications	810
727	for file descriptors, so you practically need to use non-blocking I/O (and	811	The file descriptor being watched.
728	treat callback invocation as hint only), or retest separately with a safe	812
729	interface before doing I/O (XLib can do this), or force the use of either	813	=item int events [read-only]
730	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this	814
731	problem. Also note that it is quite easy to have your callback invoked	815	The events being watched.
732	when the readyness condition is no longer valid even when employing
733	typical ways of handling events, so its a good idea to use non-blocking
734	I/O unconditionally.
735		816
736	=back	817	=back
737		818
738	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	819	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well
739	readable, but only once. Since it is likely line-buffered, you could	820	readable, but only once. Since it is likely line-buffered, you could
…		…
752	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	833	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
753	ev_io_start (loop, &stdin_readable);	834	ev_io_start (loop, &stdin_readable);
754	ev_loop (loop, 0);	835	ev_loop (loop, 0);
755		836
756		837
757	=head2 C<ev_timer> - relative and optionally recurring timeouts	838	=head2 C<ev_timer> - relative and optionally repeating timeouts
758		839
759	Timer watchers are simple relative timers that generate an event after a	840	Timer watchers are simple relative timers that generate an event after a
760	given time, and optionally repeating in regular intervals after that.	841	given time, and optionally repeating in regular intervals after that.
761		842
762	The timers are based on real time, that is, if you register an event that	843	The timers are based on real time, that is, if you register an event that
…		…
803		884
804	If the timer is repeating, either start it if necessary (with the repeat	885	If the timer is repeating, either start it if necessary (with the repeat
805	value), or reset the running timer to the repeat value.	886	value), or reset the running timer to the repeat value.
806		887
807	This sounds a bit complicated, but here is a useful and typical	888	This sounds a bit complicated, but here is a useful and typical
808	example: Imagine you have a tcp connection and you want a so-called idle	889	example: Imagine you have a tcp connection and you want a so-called
809	timeout, that is, you want to be called when there have been, say, 60	890	idle timeout, that is, you want to be called when there have been,
810	seconds of inactivity on the socket. The easiest way to do this is to	891	say, 60 seconds of inactivity on the socket. The easiest way to do
811	configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each	892	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling
812	time you successfully read or write some data. If you go into an idle	893	C<ev_timer_again> each time you successfully read or write some data. If
813	state where you do not expect data to travel on the socket, you can stop	894	you go into an idle state where you do not expect data to travel on the
814	the timer, and again will automatically restart it if need be.	895	socket, you can stop the timer, and again will automatically restart it if
		896	need be.
		897
		898	You can also ignore the C<after> value and C<ev_timer_start> altogether
		899	and only ever use the C<repeat> value:
		900
		901	ev_timer_init (timer, callback, 0., 5.);
		902	ev_timer_again (loop, timer);
		903	...
		904	timer->again = 17.;
		905	ev_timer_again (loop, timer);
		906	...
		907	timer->again = 10.;
		908	ev_timer_again (loop, timer);
		909
		910	This is more efficient then stopping/starting the timer eahc time you want
		911	to modify its timeout value.
		912
		913	=item ev_tstamp repeat [read-write]
		914
		915	The current C<repeat> value. Will be used each time the watcher times out
		916	or C<ev_timer_again> is called and determines the next timeout (if any),
		917	which is also when any modifications are taken into account.
815		918
816	=back	919	=back
817		920
818	Example: create a timer that fires after 60 seconds.	921	Example: create a timer that fires after 60 seconds.
819		922
…		…
844	// and in some piece of code that gets executed on any "activity":	947	// and in some piece of code that gets executed on any "activity":
845	// reset the timeout to start ticking again at 10 seconds	948	// reset the timeout to start ticking again at 10 seconds
846	ev_timer_again (&mytimer);	949	ev_timer_again (&mytimer);
847		950
848		951
849	=head2 C<ev_periodic> - to cron or not to cron	952	=head2 C<ev_periodic> - to cron or not to cron?
850		953
851	Periodic watchers are also timers of a kind, but they are very versatile	954	Periodic watchers are also timers of a kind, but they are very versatile
852	(and unfortunately a bit complex).	955	(and unfortunately a bit complex).
853		956
854	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	957	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
855	but on wallclock time (absolute time). You can tell a periodic watcher	958	but on wallclock time (absolute time). You can tell a periodic watcher
856	to trigger "at" some specific point in time. For example, if you tell a	959	to trigger "at" some specific point in time. For example, if you tell a
857	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	960	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
858	+ 10.>) and then reset your system clock to the last year, then it will	961	+ 10.>) and then reset your system clock to the last year, then it will
859	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	962	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
860	roughly 10 seconds later and of course not if you reset your system time	963	roughly 10 seconds later and of course not if you reset your system time
861	again).	964	again).
862		965
…		…
946	Simply stops and restarts the periodic watcher again. This is only useful	1049	Simply stops and restarts the periodic watcher again. This is only useful
947	when you changed some parameters or the reschedule callback would return	1050	when you changed some parameters or the reschedule callback would return
948	a different time than the last time it was called (e.g. in a crond like	1051	a different time than the last time it was called (e.g. in a crond like
949	program when the crontabs have changed).	1052	program when the crontabs have changed).
950		1053
		1054	=item ev_tstamp interval [read-write]
		1055
		1056	The current interval value. Can be modified any time, but changes only
		1057	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1058	called.
		1059
		1060	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
		1061
		1062	The current reschedule callback, or C<0>, if this functionality is
		1063	switched off. Can be changed any time, but changes only take effect when
		1064	the periodic timer fires or C<ev_periodic_again> is being called.
		1065
951	=back	1066	=back
952		1067
953	Example: call a callback every hour, or, more precisely, whenever the	1068	Example: call a callback every hour, or, more precisely, whenever the
954	system clock is divisible by 3600. The callback invocation times have	1069	system clock is divisible by 3600. The callback invocation times have
955	potentially a lot of jittering, but good long-term stability.	1070	potentially a lot of jittering, but good long-term stability.
…		…
982	ev_periodic_init (&hourly_tick, clock_cb,	1097	ev_periodic_init (&hourly_tick, clock_cb,
983	fmod (ev_now (loop), 3600.), 3600., 0);	1098	fmod (ev_now (loop), 3600.), 3600., 0);
984	ev_periodic_start (loop, &hourly_tick);	1099	ev_periodic_start (loop, &hourly_tick);
985		1100
986		1101
987	=head2 C<ev_signal> - signal me when a signal gets signalled	1102	=head2 C<ev_signal> - signal me when a signal gets signalled!
988		1103
989	Signal watchers will trigger an event when the process receives a specific	1104	Signal watchers will trigger an event when the process receives a specific
990	signal one or more times. Even though signals are very asynchronous, libev	1105	signal one or more times. Even though signals are very asynchronous, libev
991	will try it's best to deliver signals synchronously, i.e. as part of the	1106	will try it's best to deliver signals synchronously, i.e. as part of the
992	normal event processing, like any other event.	1107	normal event processing, like any other event.
…		…
1005	=item ev_signal_set (ev_signal *, int signum)	1120	=item ev_signal_set (ev_signal *, int signum)
1006		1121
1007	Configures the watcher to trigger on the given signal number (usually one	1122	Configures the watcher to trigger on the given signal number (usually one
1008	of the C<SIGxxx> constants).	1123	of the C<SIGxxx> constants).
1009		1124
		1125	=item int signum [read-only]
		1126
		1127	The signal the watcher watches out for.
		1128
1010	=back	1129	=back
1011		1130
1012		1131
1013	=head2 C<ev_child> - wait for pid status changes	1132	=head2 C<ev_child> - watch out for process status changes
1014		1133
1015	Child watchers trigger when your process receives a SIGCHLD in response to	1134	Child watchers trigger when your process receives a SIGCHLD in response to
1016	some child status changes (most typically when a child of yours dies).	1135	some child status changes (most typically when a child of yours dies).
1017		1136
1018	=over 4	1137	=over 4
…		…
1026	at the C<rstatus> member of the C<ev_child> watcher structure to see	1145	at the C<rstatus> member of the C<ev_child> watcher structure to see
1027	the status word (use the macros from C<sys/wait.h> and see your systems	1146	the status word (use the macros from C<sys/wait.h> and see your systems
1028	C<waitpid> documentation). The C<rpid> member contains the pid of the	1147	C<waitpid> documentation). The C<rpid> member contains the pid of the
1029	process causing the status change.	1148	process causing the status change.
1030		1149
		1150	=item int pid [read-only]
		1151
		1152	The process id this watcher watches out for, or C<0>, meaning any process id.
		1153
		1154	=item int rpid [read-write]
		1155
		1156	The process id that detected a status change.
		1157
		1158	=item int rstatus [read-write]
		1159
		1160	The process exit/trace status caused by C<rpid> (see your systems
		1161	C<waitpid> and C<sys/wait.h> documentation for details).
		1162
1031	=back	1163	=back
1032		1164
1033	Example: try to exit cleanly on SIGINT and SIGTERM.	1165	Example: try to exit cleanly on SIGINT and SIGTERM.
1034		1166
1035	static void	1167	static void
…		…
1041	struct ev_signal signal_watcher;	1173	struct ev_signal signal_watcher;
1042	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1174	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1043	ev_signal_start (loop, &sigint_cb);	1175	ev_signal_start (loop, &sigint_cb);
1044		1176
1045		1177
		1178	=head2 C<ev_stat> - did the file attributes just change?
		1179
		1180	This watches a filesystem path for attribute changes. That is, it calls
		1181	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1182	compared to the last time, invoking the callback if it did.
		1183
		1184	The path does not need to exist: changing from "path exists" to "path does
		1185	not exist" is a status change like any other. The condition "path does
		1186	not exist" is signified by the C<st_nlink> field being zero (which is
		1187	otherwise always forced to be at least one) and all the other fields of
		1188	the stat buffer having unspecified contents.
		1189
		1190	Since there is no standard to do this, the portable implementation simply
		1191	calls C<stat (2)> regulalry on the path to see if it changed somehow. You
		1192	can specify a recommended polling interval for this case. If you specify
		1193	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1194	unspecified default> value will be used (which you can expect to be around
		1195	five seconds, although this might change dynamically). Libev will also
		1196	impose a minimum interval which is currently around C<0.1>, but thats
		1197	usually overkill.
		1198
		1199	This watcher type is not meant for massive numbers of stat watchers,
		1200	as even with OS-supported change notifications, this can be
		1201	resource-intensive.
		1202
		1203	At the time of this writing, no specific OS backends are implemented, but
		1204	if demand increases, at least a kqueue and inotify backend will be added.
		1205
		1206	=over 4
		1207
		1208	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
		1209
		1210	=item ev_stat_set (ev_stat , const char path, ev_tstamp interval)
		1211
		1212	Configures the watcher to wait for status changes of the given
		1213	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1214	be detected and should normally be specified as C<0> to let libev choose
		1215	a suitable value. The memory pointed to by C<path> must point to the same
		1216	path for as long as the watcher is active.
		1217
		1218	The callback will be receive C<EV_STAT> when a change was detected,
		1219	relative to the attributes at the time the watcher was started (or the
		1220	last change was detected).
		1221
		1222	=item ev_stat_stat (ev_stat *)
		1223
		1224	Updates the stat buffer immediately with new values. If you change the
		1225	watched path in your callback, you could call this fucntion to avoid
		1226	detecting this change (while introducing a race condition). Can also be
		1227	useful simply to find out the new values.
		1228
		1229	=item ev_statdata attr [read-only]
		1230
		1231	The most-recently detected attributes of the file. Although the type is of
		1232	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1233	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1234	was some error while C<stat>ing the file.
		1235
		1236	=item ev_statdata prev [read-only]
		1237
		1238	The previous attributes of the file. The callback gets invoked whenever
		1239	C<prev> != C<attr>.
		1240
		1241	=item ev_tstamp interval [read-only]
		1242
		1243	The specified interval.
		1244
		1245	=item const char *path [read-only]
		1246
		1247	The filesystem path that is being watched.
		1248
		1249	=back
		1250
		1251	Example: Watch C</etc/passwd> for attribute changes.
		1252
		1253	static void
		1254	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1255	{
		1256	/* /etc/passwd changed in some way */
		1257	if (w->attr.st_nlink)
		1258	{
		1259	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1260	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1261	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1262	}
		1263	else
		1264	/* you shalt not abuse printf for puts */
		1265	puts ("wow, /etc/passwd is not there, expect problems. "
		1266	"if this is windows, they already arrived\n");
		1267	}
		1268
		1269	...
		1270	ev_stat passwd;
		1271
		1272	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1273	ev_stat_start (loop, &passwd);
		1274
		1275
1046	=head2 C<ev_idle> - when you've got nothing better to do	1276	=head2 C<ev_idle> - when you've got nothing better to do...
1047		1277
1048	Idle watchers trigger events when there are no other events are pending	1278	Idle watchers trigger events when there are no other events are pending
1049	(prepare, check and other idle watchers do not count). That is, as long	1279	(prepare, check and other idle watchers do not count). That is, as long
1050	as your process is busy handling sockets or timeouts (or even signals,	1280	as your process is busy handling sockets or timeouts (or even signals,
1051	imagine) it will not be triggered. But when your process is idle all idle	1281	imagine) it will not be triggered. But when your process is idle all idle
…		…
1085	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1315	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1086	ev_idle_init (idle_watcher, idle_cb);	1316	ev_idle_init (idle_watcher, idle_cb);
1087	ev_idle_start (loop, idle_cb);	1317	ev_idle_start (loop, idle_cb);
1088		1318
1089		1319
1090	=head2 C<ev_prepare> and C<ev_check> - customise your event loop	1320	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1091		1321
1092	Prepare and check watchers are usually (but not always) used in tandem:	1322	Prepare and check watchers are usually (but not always) used in tandem:
1093	prepare watchers get invoked before the process blocks and check watchers	1323	prepare watchers get invoked before the process blocks and check watchers
1094	afterwards.	1324	afterwards.
1095		1325
		1326	You I<must not> call C<ev_loop> or similar functions that enter
		1327	the current event loop from either C<ev_prepare> or C<ev_check>
		1328	watchers. Other loops than the current one are fine, however. The
		1329	rationale behind this is that you do not need to check for recursion in
		1330	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
		1331	C<ev_check> so if you have one watcher of each kind they will always be
		1332	called in pairs bracketing the blocking call.
		1333
1096	Their main purpose is to integrate other event mechanisms into libev and	1334	Their main purpose is to integrate other event mechanisms into libev and
1097	their use is somewhat advanced. This could be used, for example, to track	1335	their use is somewhat advanced. This could be used, for example, to track
1098	variable changes, implement your own watchers, integrate net-snmp or a	1336	variable changes, implement your own watchers, integrate net-snmp or a
1099	coroutine library and lots more.	1337	coroutine library and lots more. They are also occasionally useful if
		1338	you cache some data and want to flush it before blocking (for example,
		1339	in X programs you might want to do an C<XFlush ()> in an C<ev_prepare>
		1340	watcher).
1100		1341
1101	This is done by examining in each prepare call which file descriptors need	1342	This is done by examining in each prepare call which file descriptors need
1102	to be watched by the other library, registering C<ev_io> watchers for	1343	to be watched by the other library, registering C<ev_io> watchers for
1103	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1344	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1104	provide just this functionality). Then, in the check watcher you check for	1345	provide just this functionality). Then, in the check watcher you check for
…		…
1126	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1367	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1127	macros, but using them is utterly, utterly and completely pointless.	1368	macros, but using them is utterly, utterly and completely pointless.
1128		1369
1129	=back	1370	=back
1130		1371
1131	Example: TODO.	1372	Example: To include a library such as adns, you would add IO watchers
		1373	and a timeout watcher in a prepare handler, as required by libadns, and
		1374	in a check watcher, destroy them and call into libadns. What follows is
		1375	pseudo-code only of course:
1132		1376
		1377	static ev_io iow [nfd];
		1378	static ev_timer tw;
1133		1379
		1380	static void
		1381	io_cb (ev_loop loop, ev_io w, int revents)
		1382	{
		1383	// set the relevant poll flags
		1384	// could also call adns_processreadable etc. here
		1385	struct pollfd fd = (struct pollfd )w->data;
		1386	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1387	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1388	}
		1389
		1390	// create io watchers for each fd and a timer before blocking
		1391	static void
		1392	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1393	{
		1394	int timeout = 3600000;truct pollfd fds [nfd];
		1395	// actual code will need to loop here and realloc etc.
		1396	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1397
		1398	/* the callback is illegal, but won't be called as we stop during check */
		1399	ev_timer_init (&tw, 0, timeout * 1e-3);
		1400	ev_timer_start (loop, &tw);
		1401
		1402	// create on ev_io per pollfd
		1403	for (int i = 0; i < nfd; ++i)
		1404	{
		1405	ev_io_init (iow + i, io_cb, fds [i].fd,
		1406	((fds [i].events & POLLIN ? EV_READ : 0)
		1407	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1408
		1409	fds [i].revents = 0;
		1410	iow [i].data = fds + i;
		1411	ev_io_start (loop, iow + i);
		1412	}
		1413	}
		1414
		1415	// stop all watchers after blocking
		1416	static void
		1417	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1418	{
		1419	ev_timer_stop (loop, &tw);
		1420
		1421	for (int i = 0; i < nfd; ++i)
		1422	ev_io_stop (loop, iow + i);
		1423
		1424	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1425	}
		1426
		1427
1134	=head2 C<ev_embed> - when one backend isn't enough	1428	=head2 C<ev_embed> - when one backend isn't enough...
1135		1429
1136	This is a rather advanced watcher type that lets you embed one event loop	1430	This is a rather advanced watcher type that lets you embed one event loop
1137	into another (currently only C<ev_io> events are supported in the embedded	1431	into another (currently only C<ev_io> events are supported in the embedded
1138	loop, other types of watchers might be handled in a delayed or incorrect	1432	loop, other types of watchers might be handled in a delayed or incorrect
1139	fashion and must not be used).	1433	fashion and must not be used).
…		…
1217		1511
1218	Make a single, non-blocking sweep over the embedded loop. This works	1512	Make a single, non-blocking sweep over the embedded loop. This works
1219	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1513	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1220	apropriate way for embedded loops.	1514	apropriate way for embedded loops.
1221		1515
		1516	=item struct ev_loop *loop [read-only]
		1517
		1518	The embedded event loop.
		1519
		1520	=back
		1521
		1522
		1523	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1524
		1525	Fork watchers are called when a C<fork ()> was detected (usually because
		1526	whoever is a good citizen cared to tell libev about it by calling
		1527	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1528	event loop blocks next and before C<ev_check> watchers are being called,
		1529	and only in the child after the fork. If whoever good citizen calling
		1530	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1531	handlers will be invoked, too, of course.
		1532
		1533	=over 4
		1534
		1535	=item ev_fork_init (ev_signal *, callback)
		1536
		1537	Initialises and configures the fork watcher - it has no parameters of any
		1538	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1539	believe me.
		1540
1222	=back	1541	=back
1223		1542
1224		1543
1225	=head1 OTHER FUNCTIONS	1544	=head1 OTHER FUNCTIONS
1226		1545
…		…
1306		1625
1307	=back	1626	=back
1308		1627
1309	=head1 C++ SUPPORT	1628	=head1 C++ SUPPORT
1310		1629
1311	TBD.	1630	Libev comes with some simplistic wrapper classes for C++ that mainly allow
		1631	you to use some convinience methods to start/stop watchers and also change
		1632	the callback model to a model using method callbacks on objects.
		1633
		1634	To use it,
		1635
		1636	#include <ev++.h>
		1637
		1638	(it is not installed by default). This automatically includes F<ev.h>
		1639	and puts all of its definitions (many of them macros) into the global
		1640	namespace. All C++ specific things are put into the C<ev> namespace.
		1641
		1642	It should support all the same embedding options as F<ev.h>, most notably
		1643	C<EV_MULTIPLICITY>.
		1644
		1645	Here is a list of things available in the C<ev> namespace:
		1646
		1647	=over 4
		1648
		1649	=item C<ev::READ>, C<ev::WRITE> etc.
		1650
		1651	These are just enum values with the same values as the C<EV_READ> etc.
		1652	macros from F<ev.h>.
		1653
		1654	=item C<ev::tstamp>, C<ev::now>
		1655
		1656	Aliases to the same types/functions as with the C<ev_> prefix.
		1657
		1658	=item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc.
		1659
		1660	For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of
		1661	the same name in the C<ev> namespace, with the exception of C<ev_signal>
		1662	which is called C<ev::sig> to avoid clashes with the C<signal> macro
		1663	defines by many implementations.
		1664
		1665	All of those classes have these methods:
		1666
		1667	=over 4
		1668
		1669	=item ev::TYPE::TYPE (object , object::method )
		1670
		1671	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)
		1672
		1673	=item ev::TYPE::~TYPE
		1674
		1675	The constructor takes a pointer to an object and a method pointer to
		1676	the event handler callback to call in this class. The constructor calls
		1677	C<ev_init> for you, which means you have to call the C<set> method
		1678	before starting it. If you do not specify a loop then the constructor
		1679	automatically associates the default loop with this watcher.
		1680
		1681	The destructor automatically stops the watcher if it is active.
		1682
		1683	=item w->set (struct ev_loop *)
		1684
		1685	Associates a different C<struct ev_loop> with this watcher. You can only
		1686	do this when the watcher is inactive (and not pending either).
		1687
		1688	=item w->set ([args])
		1689
		1690	Basically the same as C<ev_TYPE_set>, with the same args. Must be
		1691	called at least once. Unlike the C counterpart, an active watcher gets
		1692	automatically stopped and restarted.
		1693
		1694	=item w->start ()
		1695
		1696	Starts the watcher. Note that there is no C<loop> argument as the
		1697	constructor already takes the loop.
		1698
		1699	=item w->stop ()
		1700
		1701	Stops the watcher if it is active. Again, no C<loop> argument.
		1702
		1703	=item w->again () C<ev::timer>, C<ev::periodic> only
		1704
		1705	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
		1706	C<ev_TYPE_again> function.
		1707
		1708	=item w->sweep () C<ev::embed> only
		1709
		1710	Invokes C<ev_embed_sweep>.
		1711
		1712	=item w->update () C<ev::stat> only
		1713
		1714	Invokes C<ev_stat_stat>.
		1715
		1716	=back
		1717
		1718	=back
		1719
		1720	Example: Define a class with an IO and idle watcher, start one of them in
		1721	the constructor.
		1722
		1723	class myclass
		1724	{
		1725	ev_io io; void io_cb (ev::io &w, int revents);
		1726	ev_idle idle void idle_cb (ev::idle &w, int revents);
		1727
		1728	myclass ();
		1729	}
		1730
		1731	myclass::myclass (int fd)
		1732	: io (this, &myclass::io_cb),
		1733	idle (this, &myclass::idle_cb)
		1734	{
		1735	io.start (fd, ev::READ);
		1736	}
		1737
		1738
		1739	=head1 MACRO MAGIC
		1740
		1741	Libev can be compiled with a variety of options, the most fundemantal is
		1742	C<EV_MULTIPLICITY>. This option determines wether (most) functions and
		1743	callbacks have an initial C<struct ev_loop *> argument.
		1744
		1745	To make it easier to write programs that cope with either variant, the
		1746	following macros are defined:
		1747
		1748	=over 4
		1749
		1750	=item C<EV_A>, C<EV_A_>
		1751
		1752	This provides the loop I<argument> for functions, if one is required ("ev
		1753	loop argument"). The C<EV_A> form is used when this is the sole argument,
		1754	C<EV_A_> is used when other arguments are following. Example:
		1755
		1756	ev_unref (EV_A);
		1757	ev_timer_add (EV_A_ watcher);
		1758	ev_loop (EV_A_ 0);
		1759
		1760	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		1761	which is often provided by the following macro.
		1762
		1763	=item C<EV_P>, C<EV_P_>
		1764
		1765	This provides the loop I<parameter> for functions, if one is required ("ev
		1766	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		1767	C<EV_P_> is used when other parameters are following. Example:
		1768
		1769	// this is how ev_unref is being declared
		1770	static void ev_unref (EV_P);
		1771
		1772	// this is how you can declare your typical callback
		1773	static void cb (EV_P_ ev_timer *w, int revents)
		1774
		1775	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		1776	suitable for use with C<EV_A>.
		1777
		1778	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		1779
		1780	Similar to the other two macros, this gives you the value of the default
		1781	loop, if multiple loops are supported ("ev loop default").
		1782
		1783	=back
		1784
		1785	Example: Declare and initialise a check watcher, working regardless of
		1786	wether multiple loops are supported or not.
		1787
		1788	static void
		1789	check_cb (EV_P_ ev_timer *w, int revents)
		1790	{
		1791	ev_check_stop (EV_A_ w);
		1792	}
		1793
		1794	ev_check check;
		1795	ev_check_init (&check, check_cb);
		1796	ev_check_start (EV_DEFAULT_ &check);
		1797	ev_loop (EV_DEFAULT_ 0);
		1798
		1799
		1800	=head1 EMBEDDING
		1801
		1802	Libev can (and often is) directly embedded into host
		1803	applications. Examples of applications that embed it include the Deliantra
		1804	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
		1805	and rxvt-unicode.
		1806
		1807	The goal is to enable you to just copy the neecssary files into your
		1808	source directory without having to change even a single line in them, so
		1809	you can easily upgrade by simply copying (or having a checked-out copy of
		1810	libev somewhere in your source tree).
		1811
		1812	=head2 FILESETS
		1813
		1814	Depending on what features you need you need to include one or more sets of files
		1815	in your app.
		1816
		1817	=head3 CORE EVENT LOOP
		1818
		1819	To include only the libev core (all the C<ev_*> functions), with manual
		1820	configuration (no autoconf):
		1821
		1822	#define EV_STANDALONE 1
		1823	#include "ev.c"
		1824
		1825	This will automatically include F<ev.h>, too, and should be done in a
		1826	single C source file only to provide the function implementations. To use
		1827	it, do the same for F<ev.h> in all files wishing to use this API (best
		1828	done by writing a wrapper around F<ev.h> that you can include instead and
		1829	where you can put other configuration options):
		1830
		1831	#define EV_STANDALONE 1
		1832	#include "ev.h"
		1833
		1834	Both header files and implementation files can be compiled with a C++
		1835	compiler (at least, thats a stated goal, and breakage will be treated
		1836	as a bug).
		1837
		1838	You need the following files in your source tree, or in a directory
		1839	in your include path (e.g. in libev/ when using -Ilibev):
		1840
		1841	ev.h
		1842	ev.c
		1843	ev_vars.h
		1844	ev_wrap.h
		1845
		1846	ev_win32.c required on win32 platforms only
		1847
		1848	ev_select.c only when select backend is enabled (which is by default)
		1849	ev_poll.c only when poll backend is enabled (disabled by default)
		1850	ev_epoll.c only when the epoll backend is enabled (disabled by default)
		1851	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		1852	ev_port.c only when the solaris port backend is enabled (disabled by default)
		1853
		1854	F<ev.c> includes the backend files directly when enabled, so you only need
		1855	to compile this single file.
		1856
		1857	=head3 LIBEVENT COMPATIBILITY API
		1858
		1859	To include the libevent compatibility API, also include:
		1860
		1861	#include "event.c"
		1862
		1863	in the file including F<ev.c>, and:
		1864
		1865	#include "event.h"
		1866
		1867	in the files that want to use the libevent API. This also includes F<ev.h>.
		1868
		1869	You need the following additional files for this:
		1870
		1871	event.h
		1872	event.c
		1873
		1874	=head3 AUTOCONF SUPPORT
		1875
		1876	Instead of using C<EV_STANDALONE=1> and providing your config in
		1877	whatever way you want, you can also C<m4_include([libev.m4])> in your
		1878	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
		1879	include F<config.h> and configure itself accordingly.
		1880
		1881	For this of course you need the m4 file:
		1882
		1883	libev.m4
		1884
		1885	=head2 PREPROCESSOR SYMBOLS/MACROS
		1886
		1887	Libev can be configured via a variety of preprocessor symbols you have to define
		1888	before including any of its files. The default is not to build for multiplicity
		1889	and only include the select backend.
		1890
		1891	=over 4
		1892
		1893	=item EV_STANDALONE
		1894
		1895	Must always be C<1> if you do not use autoconf configuration, which
		1896	keeps libev from including F<config.h>, and it also defines dummy
		1897	implementations for some libevent functions (such as logging, which is not
		1898	supported). It will also not define any of the structs usually found in
		1899	F<event.h> that are not directly supported by the libev core alone.
		1900
		1901	=item EV_USE_MONOTONIC
		1902
		1903	If defined to be C<1>, libev will try to detect the availability of the
		1904	monotonic clock option at both compiletime and runtime. Otherwise no use
		1905	of the monotonic clock option will be attempted. If you enable this, you
		1906	usually have to link against librt or something similar. Enabling it when
		1907	the functionality isn't available is safe, though, althoguh you have
		1908	to make sure you link against any libraries where the C<clock_gettime>
		1909	function is hiding in (often F<-lrt>).
		1910
		1911	=item EV_USE_REALTIME
		1912
		1913	If defined to be C<1>, libev will try to detect the availability of the
		1914	realtime clock option at compiletime (and assume its availability at
		1915	runtime if successful). Otherwise no use of the realtime clock option will
		1916	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
		1917	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries
		1918	in the description of C<EV_USE_MONOTONIC>, though.
		1919
		1920	=item EV_USE_SELECT
		1921
		1922	If undefined or defined to be C<1>, libev will compile in support for the
		1923	C<select>(2) backend. No attempt at autodetection will be done: if no
		1924	other method takes over, select will be it. Otherwise the select backend
		1925	will not be compiled in.
		1926
		1927	=item EV_SELECT_USE_FD_SET
		1928
		1929	If defined to C<1>, then the select backend will use the system C<fd_set>
		1930	structure. This is useful if libev doesn't compile due to a missing
		1931	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on
		1932	exotic systems. This usually limits the range of file descriptors to some
		1933	low limit such as 1024 or might have other limitations (winsocket only
		1934	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
		1935	influence the size of the C<fd_set> used.
		1936
		1937	=item EV_SELECT_IS_WINSOCKET
		1938
		1939	When defined to C<1>, the select backend will assume that
		1940	select/socket/connect etc. don't understand file descriptors but
		1941	wants osf handles on win32 (this is the case when the select to
		1942	be used is the winsock select). This means that it will call
		1943	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
		1944	it is assumed that all these functions actually work on fds, even
		1945	on win32. Should not be defined on non-win32 platforms.
		1946
		1947	=item EV_USE_POLL
		1948
		1949	If defined to be C<1>, libev will compile in support for the C<poll>(2)
		1950	backend. Otherwise it will be enabled on non-win32 platforms. It
		1951	takes precedence over select.
		1952
		1953	=item EV_USE_EPOLL
		1954
		1955	If defined to be C<1>, libev will compile in support for the Linux
		1956	C<epoll>(7) backend. Its availability will be detected at runtime,
		1957	otherwise another method will be used as fallback. This is the
		1958	preferred backend for GNU/Linux systems.
		1959
		1960	=item EV_USE_KQUEUE
		1961
		1962	If defined to be C<1>, libev will compile in support for the BSD style
		1963	C<kqueue>(2) backend. Its actual availability will be detected at runtime,
		1964	otherwise another method will be used as fallback. This is the preferred
		1965	backend for BSD and BSD-like systems, although on most BSDs kqueue only
		1966	supports some types of fds correctly (the only platform we found that
		1967	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		1968	not be used unless explicitly requested. The best way to use it is to find
		1969	out whether kqueue supports your type of fd properly and use an embedded
		1970	kqueue loop.
		1971
		1972	=item EV_USE_PORT
		1973
		1974	If defined to be C<1>, libev will compile in support for the Solaris
		1975	10 port style backend. Its availability will be detected at runtime,
		1976	otherwise another method will be used as fallback. This is the preferred
		1977	backend for Solaris 10 systems.
		1978
		1979	=item EV_USE_DEVPOLL
		1980
		1981	reserved for future expansion, works like the USE symbols above.
		1982
		1983	=item EV_H
		1984
		1985	The name of the F<ev.h> header file used to include it. The default if
		1986	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
		1987	can be used to virtually rename the F<ev.h> header file in case of conflicts.
		1988
		1989	=item EV_CONFIG_H
		1990
		1991	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
		1992	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
		1993	C<EV_H>, above.
		1994
		1995	=item EV_EVENT_H
		1996
		1997	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
		1998	of how the F<event.h> header can be found.
		1999
		2000	=item EV_PROTOTYPES
		2001
		2002	If defined to be C<0>, then F<ev.h> will not define any function
		2003	prototypes, but still define all the structs and other symbols. This is
		2004	occasionally useful if you want to provide your own wrapper functions
		2005	around libev functions.
		2006
		2007	=item EV_MULTIPLICITY
		2008
		2009	If undefined or defined to C<1>, then all event-loop-specific functions
		2010	will have the C<struct ev_loop *> as first argument, and you can create
		2011	additional independent event loops. Otherwise there will be no support
		2012	for multiple event loops and there is no first event loop pointer
		2013	argument. Instead, all functions act on the single default loop.
		2014
		2015	=item EV_PERIODIC_ENABLE
		2016
		2017	If undefined or defined to be C<1>, then periodic timers are supported. If
		2018	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2019	code.
		2020
		2021	=item EV_EMBED_ENABLE
		2022
		2023	If undefined or defined to be C<1>, then embed watchers are supported. If
		2024	defined to be C<0>, then they are not.
		2025
		2026	=item EV_STAT_ENABLE
		2027
		2028	If undefined or defined to be C<1>, then stat watchers are supported. If
		2029	defined to be C<0>, then they are not.
		2030
		2031	=item EV_FORK_ENABLE
		2032
		2033	If undefined or defined to be C<1>, then fork watchers are supported. If
		2034	defined to be C<0>, then they are not.
		2035
		2036	=item EV_MINIMAL
		2037
		2038	If you need to shave off some kilobytes of code at the expense of some
		2039	speed, define this symbol to C<1>. Currently only used for gcc to override
		2040	some inlining decisions, saves roughly 30% codesize of amd64.
		2041
		2042	=item EV_PID_HASHSIZE
		2043
		2044	C<ev_child> watchers use a small hash table to distribute workload by
		2045	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2046	than enough. If you need to manage thousands of children you might want to
		2047	increase this value.
		2048
		2049	=item EV_COMMON
		2050
		2051	By default, all watchers have a C<void *data> member. By redefining
		2052	this macro to a something else you can include more and other types of
		2053	members. You have to define it each time you include one of the files,
		2054	though, and it must be identical each time.
		2055
		2056	For example, the perl EV module uses something like this:
		2057
		2058	#define EV_COMMON \
		2059	SV self; / contains this struct */ \
		2060	SV cb_sv, fh /* note no trailing ";" */
		2061
		2062	=item EV_CB_DECLARE (type)
		2063
		2064	=item EV_CB_INVOKE (watcher, revents)
		2065
		2066	=item ev_set_cb (ev, cb)
		2067
		2068	Can be used to change the callback member declaration in each watcher,
		2069	and the way callbacks are invoked and set. Must expand to a struct member
		2070	definition and a statement, respectively. See the F<ev.v> header file for
		2071	their default definitions. One possible use for overriding these is to
		2072	avoid the C<struct ev_loop *> as first argument in all cases, or to use
		2073	method calls instead of plain function calls in C++.
		2074
		2075	=head2 EXAMPLES
		2076
		2077	For a real-world example of a program the includes libev
		2078	verbatim, you can have a look at the EV perl module
		2079	(L<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
		2080	the F<libev/> subdirectory and includes them in the F<EV/EVAPI.h> (public
		2081	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
		2082	will be compiled. It is pretty complex because it provides its own header
		2083	file.
		2084
		2085	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
		2086	that everybody includes and which overrides some autoconf choices:
		2087
		2088	#define EV_USE_POLL 0
		2089	#define EV_MULTIPLICITY 0
		2090	#define EV_PERIODICS 0
		2091	#define EV_CONFIG_H <config.h>
		2092
		2093	#include "ev++.h"
		2094
		2095	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
		2096
		2097	#include "ev_cpp.h"
		2098	#include "ev.c"
		2099
		2100
		2101	=head1 COMPLEXITIES
		2102
		2103	In this section the complexities of (many of) the algorithms used inside
		2104	libev will be explained. For complexity discussions about backends see the
		2105	documentation for C<ev_default_init>.
		2106
		2107	=over 4
		2108
		2109	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
		2110
		2111	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
		2112
		2113	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
		2114
		2115	=item Stopping check/prepare/idle watchers: O(1)
		2116
		2117	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))
		2118
		2119	=item Finding the next timer per loop iteration: O(1)
		2120
		2121	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
		2122
		2123	=item Activating one watcher: O(1)
		2124
		2125	=back
		2126
1312		2127
1313	=head1 AUTHOR	2128	=head1 AUTHOR
1314		2129
1315	Marc Lehmann <libev@schmorp.de>.	2130	Marc Lehmann <libev@schmorp.de>.
1316		2131

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Comparing libev/ev.pod (file contents): Revision 1.36 by root, Sat Nov 24 07:14:26 2007 UTC vs. Revision 1.53 by root, Tue Nov 27 20:15:02 2007 UTC

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Revision 1.36 by root, Sat Nov 24 07:14:26 2007 UTC vs.
Revision 1.53 by root, Tue Nov 27 20:15:02 2007 UTC