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

Comparing libev/ev.pod (file contents):
Revision 1.37 by root, Sat Nov 24 07:20:43 2007 UTC vs.
Revision 1.50 by root, Tue Nov 27 10:59:11 2007 UTC

…		…
47	(fractional) number of seconds since the (POSIX) epoch (somewhere near	47	(fractional) number of seconds since the (POSIX) epoch (somewhere near
48	the beginning of 1970, details are complicated, don't ask). This type is	48	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	49	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	50	to the C<double> type in C, and when you need to do any calculations on
51	it, you should treat it as such.	51	it, you should treat it as such.
52
53		52
54	=head1 GLOBAL FUNCTIONS	53	=head1 GLOBAL FUNCTIONS
55		54
56	These functions can be called anytime, even before initialising the	55	These functions can be called anytime, even before initialising the
57	library in any way.	56	library in any way.
…		…
468	ev_ref (myloop);	467	ev_ref (myloop);
469	ev_signal_stop (myloop, &exitsig);	468	ev_signal_stop (myloop, &exitsig);
470		469
471	=back	470	=back
472		471
		472
473	=head1 ANATOMY OF A WATCHER	473	=head1 ANATOMY OF A WATCHER
474		474
475	A watcher is a structure that you create and register to record your	475	A watcher is a structure that you create and register to record your
476	interest in some event. For instance, if you want to wait for STDIN to	476	interest in some event. For instance, if you want to wait for STDIN to
477	become readable, you would create an C<ev_io> watcher for that:	477	become readable, you would create an C<ev_io> watcher for that:
…		…
543	The signal specified in the C<ev_signal> watcher has been received by a thread.	543	The signal specified in the C<ev_signal> watcher has been received by a thread.
544		544
545	=item C<EV_CHILD>	545	=item C<EV_CHILD>
546		546
547	The pid specified in the C<ev_child> watcher has received a status change.	547	The pid specified in the C<ev_child> watcher has received a status change.
		548
		549	=item C<EV_STAT>
		550
		551	The path specified in the C<ev_stat> watcher changed its attributes somehow.
548		552
549	=item C<EV_IDLE>	553	=item C<EV_IDLE>
550		554
551	The C<ev_idle> watcher has determined that you have nothing better to do.	555	The C<ev_idle> watcher has determined that you have nothing better to do.
552		556
…		…
560	received events. Callbacks of both watcher types can start and stop as	564	received events. Callbacks of both watcher types can start and stop as
561	many watchers as they want, and all of them will be taken into account	565	many watchers as they want, and all of them will be taken into account
562	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	566	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
563	C<ev_loop> from blocking).	567	C<ev_loop> from blocking).
564		568
		569	=item C<EV_EMBED>
		570
		571	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		572
		573	=item C<EV_FORK>
		574
		575	The event loop has been resumed in the child process after fork (see
		576	C<ev_fork>).
		577
565	=item C<EV_ERROR>	578	=item C<EV_ERROR>
566		579
567	An unspecified error has occured, the watcher has been stopped. This might	580	An unspecified error has occured, the watcher has been stopped. This might
568	happen because the watcher could not be properly started because libev	581	happen because the watcher could not be properly started because libev
569	ran out of memory, a file descriptor was found to be closed or any other	582	ran out of memory, a file descriptor was found to be closed or any other
…		…
576	with the error from read() or write(). This will not work in multithreaded	589	with the error from read() or write(). This will not work in multithreaded
577	programs, though, so beware.	590	programs, though, so beware.
578		591
579	=back	592	=back
580		593
581	=head2 SUMMARY OF GENERIC WATCHER FUNCTIONS	594	=head2 GENERIC WATCHER FUNCTIONS
582		595
583	In the following description, C<TYPE> stands for the watcher type,	596	In the following description, C<TYPE> stands for the watcher type,
584	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.	597	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.
585		598
586	=over 4	599	=over 4
…		…
595	which rolls both calls into one.	608	which rolls both calls into one.
596		609
597	You can reinitialise a watcher at any time as long as it has been stopped	610	You can reinitialise a watcher at any time as long as it has been stopped
598	(or never started) and there are no pending events outstanding.	611	(or never started) and there are no pending events outstanding.
599		612
600	The callbakc is always of type C<void ()(ev_loop loop, ev_TYPE *watcher,	613	The callback is always of type C<void ()(ev_loop loop, ev_TYPE *watcher,
601	int revents)>.	614	int revents)>.
602		615
603	=item C<ev_TYPE_set> (ev_TYPE *, [args])	616	=item C<ev_TYPE_set> (ev_TYPE *, [args])
604		617
605	This macro initialises the type-specific parts of a watcher. You need to	618	This macro initialises the type-specific parts of a watcher. You need to
…		…
688		701
689		702
690	=head1 WATCHER TYPES	703	=head1 WATCHER TYPES
691		704
692	This section describes each watcher in detail, but will not repeat	705	This section describes each watcher in detail, but will not repeat
693	information given in the last section.	706	information given in the last section. Any initialisation/set macros,
		707	functions and members specific to the watcher type are explained.
694		708
		709	Members are additionally marked with either I<[read-only]>, meaning that,
		710	while the watcher is active, you can look at the member and expect some
		711	sensible content, but you must not modify it (you can modify it while the
		712	watcher is stopped to your hearts content), or I<[read-write]>, which
		713	means you can expect it to have some sensible content while the watcher
		714	is active, but you can also modify it. Modifying it may not do something
		715	sensible or take immediate effect (or do anything at all), but libev will
		716	not crash or malfunction in any way.
695		717
		718
696	=head2 C<ev_io> - is this file descriptor readable or writable	719	=head2 C<ev_io> - is this file descriptor readable or writable?
697		720
698	I/O watchers check whether a file descriptor is readable or writable	721	I/O watchers check whether a file descriptor is readable or writable
699	in each iteration of the event loop (This behaviour is called	722	in each iteration of the event loop, or, more precisely, when reading
700	level-triggering because you keep receiving events as long as the	723	would not block the process and writing would at least be able to write
701	condition persists. Remember you can stop the watcher if you don't want to	724	some data. This behaviour is called level-triggering because you keep
702	act on the event and neither want to receive future events).	725	receiving events as long as the condition persists. Remember you can stop
		726	the watcher if you don't want to act on the event and neither want to
		727	receive future events.
703		728
704	In general you can register as many read and/or write event watchers per	729	In general you can register as many read and/or write event watchers per
705	fd as you want (as long as you don't confuse yourself). Setting all file	730	fd as you want (as long as you don't confuse yourself). Setting all file
706	descriptors to non-blocking mode is also usually a good idea (but not	731	descriptors to non-blocking mode is also usually a good idea (but not
707	required if you know what you are doing).	732	required if you know what you are doing).
708		733
709	You have to be careful with dup'ed file descriptors, though. Some backends	734	You have to be careful with dup'ed file descriptors, though. Some backends
710	(the linux epoll backend is a notable example) cannot handle dup'ed file	735	(the linux epoll backend is a notable example) cannot handle dup'ed file
711	descriptors correctly if you register interest in two or more fds pointing	736	descriptors correctly if you register interest in two or more fds pointing
712	to the same underlying file/socket etc. description (that is, they share	737	to the same underlying file/socket/etc. description (that is, they share
713	the same underlying "file open").	738	the same underlying "file open").
714		739
715	If you must do this, then force the use of a known-to-be-good backend	740	If you must do this, then force the use of a known-to-be-good backend
716	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	741	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
717	C<EVBACKEND_POLL>).	742	C<EVBACKEND_POLL>).
718		743
		744	Another thing you have to watch out for is that it is quite easy to
		745	receive "spurious" readyness notifications, that is your callback might
		746	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
		747	because there is no data. Not only are some backends known to create a
		748	lot of those (for example solaris ports), it is very easy to get into
		749	this situation even with a relatively standard program structure. Thus
		750	it is best to always use non-blocking I/O: An extra C<read>(2) returning
		751	C<EAGAIN> is far preferable to a program hanging until some data arrives.
		752
		753	If you cannot run the fd in non-blocking mode (for example you should not
		754	play around with an Xlib connection), then you have to seperately re-test
		755	wether a file descriptor is really ready with a known-to-be good interface
		756	such as poll (fortunately in our Xlib example, Xlib already does this on
		757	its own, so its quite safe to use).
		758
719	=over 4	759	=over 4
720		760
721	=item ev_io_init (ev_io *, callback, int fd, int events)	761	=item ev_io_init (ev_io *, callback, int fd, int events)
722		762
723	=item ev_io_set (ev_io *, int fd, int events)	763	=item ev_io_set (ev_io *, int fd, int events)
724		764
725	Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive	765	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
726	events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ \|	766	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
727	EV_WRITE> to receive the given events.	767	C<EV_READ \| EV_WRITE> to receive the given events.
728		768
729	Please note that most of the more scalable backend mechanisms (for example	769	=item int fd [read-only]
730	epoll and solaris ports) can result in spurious readyness notifications	770
731	for file descriptors, so you practically need to use non-blocking I/O (and	771	The file descriptor being watched.
732	treat callback invocation as hint only), or retest separately with a safe	772
733	interface before doing I/O (XLib can do this), or force the use of either	773	=item int events [read-only]
734	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this	774
735	problem. Also note that it is quite easy to have your callback invoked	775	The events being watched.
736	when the readyness condition is no longer valid even when employing
737	typical ways of handling events, so its a good idea to use non-blocking
738	I/O unconditionally.
739		776
740	=back	777	=back
741		778
742	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	779	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well
743	readable, but only once. Since it is likely line-buffered, you could	780	readable, but only once. Since it is likely line-buffered, you could
…		…
756	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	793	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
757	ev_io_start (loop, &stdin_readable);	794	ev_io_start (loop, &stdin_readable);
758	ev_loop (loop, 0);	795	ev_loop (loop, 0);
759		796
760		797
761	=head2 C<ev_timer> - relative and optionally recurring timeouts	798	=head2 C<ev_timer> - relative and optionally repeating timeouts
762		799
763	Timer watchers are simple relative timers that generate an event after a	800	Timer watchers are simple relative timers that generate an event after a
764	given time, and optionally repeating in regular intervals after that.	801	given time, and optionally repeating in regular intervals after that.
765		802
766	The timers are based on real time, that is, if you register an event that	803	The timers are based on real time, that is, if you register an event that
…		…
807		844
808	If the timer is repeating, either start it if necessary (with the repeat	845	If the timer is repeating, either start it if necessary (with the repeat
809	value), or reset the running timer to the repeat value.	846	value), or reset the running timer to the repeat value.
810		847
811	This sounds a bit complicated, but here is a useful and typical	848	This sounds a bit complicated, but here is a useful and typical
812	example: Imagine you have a tcp connection and you want a so-called idle	849	example: Imagine you have a tcp connection and you want a so-called
813	timeout, that is, you want to be called when there have been, say, 60	850	idle timeout, that is, you want to be called when there have been,
814	seconds of inactivity on the socket. The easiest way to do this is to	851	say, 60 seconds of inactivity on the socket. The easiest way to do
815	configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each	852	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling
816	time you successfully read or write some data. If you go into an idle	853	C<ev_timer_again> each time you successfully read or write some data. If
817	state where you do not expect data to travel on the socket, you can stop	854	you go into an idle state where you do not expect data to travel on the
818	the timer, and again will automatically restart it if need be.	855	socket, you can stop the timer, and again will automatically restart it if
		856	need be.
		857
		858	You can also ignore the C<after> value and C<ev_timer_start> altogether
		859	and only ever use the C<repeat> value:
		860
		861	ev_timer_init (timer, callback, 0., 5.);
		862	ev_timer_again (loop, timer);
		863	...
		864	timer->again = 17.;
		865	ev_timer_again (loop, timer);
		866	...
		867	timer->again = 10.;
		868	ev_timer_again (loop, timer);
		869
		870	This is more efficient then stopping/starting the timer eahc time you want
		871	to modify its timeout value.
		872
		873	=item ev_tstamp repeat [read-write]
		874
		875	The current C<repeat> value. Will be used each time the watcher times out
		876	or C<ev_timer_again> is called and determines the next timeout (if any),
		877	which is also when any modifications are taken into account.
819		878
820	=back	879	=back
821		880
822	Example: create a timer that fires after 60 seconds.	881	Example: create a timer that fires after 60 seconds.
823		882
…		…
848	// and in some piece of code that gets executed on any "activity":	907	// and in some piece of code that gets executed on any "activity":
849	// reset the timeout to start ticking again at 10 seconds	908	// reset the timeout to start ticking again at 10 seconds
850	ev_timer_again (&mytimer);	909	ev_timer_again (&mytimer);
851		910
852		911
853	=head2 C<ev_periodic> - to cron or not to cron	912	=head2 C<ev_periodic> - to cron or not to cron?
854		913
855	Periodic watchers are also timers of a kind, but they are very versatile	914	Periodic watchers are also timers of a kind, but they are very versatile
856	(and unfortunately a bit complex).	915	(and unfortunately a bit complex).
857		916
858	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	917	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
859	but on wallclock time (absolute time). You can tell a periodic watcher	918	but on wallclock time (absolute time). You can tell a periodic watcher
860	to trigger "at" some specific point in time. For example, if you tell a	919	to trigger "at" some specific point in time. For example, if you tell a
861	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	920	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
862	+ 10.>) and then reset your system clock to the last year, then it will	921	+ 10.>) and then reset your system clock to the last year, then it will
863	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	922	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
864	roughly 10 seconds later and of course not if you reset your system time	923	roughly 10 seconds later and of course not if you reset your system time
865	again).	924	again).
866		925
…		…
950	Simply stops and restarts the periodic watcher again. This is only useful	1009	Simply stops and restarts the periodic watcher again. This is only useful
951	when you changed some parameters or the reschedule callback would return	1010	when you changed some parameters or the reschedule callback would return
952	a different time than the last time it was called (e.g. in a crond like	1011	a different time than the last time it was called (e.g. in a crond like
953	program when the crontabs have changed).	1012	program when the crontabs have changed).
954		1013
		1014	=item ev_tstamp interval [read-write]
		1015
		1016	The current interval value. Can be modified any time, but changes only
		1017	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1018	called.
		1019
		1020	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
		1021
		1022	The current reschedule callback, or C<0>, if this functionality is
		1023	switched off. Can be changed any time, but changes only take effect when
		1024	the periodic timer fires or C<ev_periodic_again> is being called.
		1025
955	=back	1026	=back
956		1027
957	Example: call a callback every hour, or, more precisely, whenever the	1028	Example: call a callback every hour, or, more precisely, whenever the
958	system clock is divisible by 3600. The callback invocation times have	1029	system clock is divisible by 3600. The callback invocation times have
959	potentially a lot of jittering, but good long-term stability.	1030	potentially a lot of jittering, but good long-term stability.
…		…
986	ev_periodic_init (&hourly_tick, clock_cb,	1057	ev_periodic_init (&hourly_tick, clock_cb,
987	fmod (ev_now (loop), 3600.), 3600., 0);	1058	fmod (ev_now (loop), 3600.), 3600., 0);
988	ev_periodic_start (loop, &hourly_tick);	1059	ev_periodic_start (loop, &hourly_tick);
989		1060
990		1061
991	=head2 C<ev_signal> - signal me when a signal gets signalled	1062	=head2 C<ev_signal> - signal me when a signal gets signalled!
992		1063
993	Signal watchers will trigger an event when the process receives a specific	1064	Signal watchers will trigger an event when the process receives a specific
994	signal one or more times. Even though signals are very asynchronous, libev	1065	signal one or more times. Even though signals are very asynchronous, libev
995	will try it's best to deliver signals synchronously, i.e. as part of the	1066	will try it's best to deliver signals synchronously, i.e. as part of the
996	normal event processing, like any other event.	1067	normal event processing, like any other event.
…		…
1009	=item ev_signal_set (ev_signal *, int signum)	1080	=item ev_signal_set (ev_signal *, int signum)
1010		1081
1011	Configures the watcher to trigger on the given signal number (usually one	1082	Configures the watcher to trigger on the given signal number (usually one
1012	of the C<SIGxxx> constants).	1083	of the C<SIGxxx> constants).
1013		1084
1014	=back	1085	=item int signum [read-only]
1015		1086
		1087	The signal the watcher watches out for.
1016		1088
		1089	=back
		1090
		1091
1017	=head2 C<ev_child> - wait for pid status changes	1092	=head2 C<ev_child> - watch out for process status changes
1018		1093
1019	Child watchers trigger when your process receives a SIGCHLD in response to	1094	Child watchers trigger when your process receives a SIGCHLD in response to
1020	some child status changes (most typically when a child of yours dies).	1095	some child status changes (most typically when a child of yours dies).
1021		1096
1022	=over 4	1097	=over 4
…		…
1030	at the C<rstatus> member of the C<ev_child> watcher structure to see	1105	at the C<rstatus> member of the C<ev_child> watcher structure to see
1031	the status word (use the macros from C<sys/wait.h> and see your systems	1106	the status word (use the macros from C<sys/wait.h> and see your systems
1032	C<waitpid> documentation). The C<rpid> member contains the pid of the	1107	C<waitpid> documentation). The C<rpid> member contains the pid of the
1033	process causing the status change.	1108	process causing the status change.
1034		1109
		1110	=item int pid [read-only]
		1111
		1112	The process id this watcher watches out for, or C<0>, meaning any process id.
		1113
		1114	=item int rpid [read-write]
		1115
		1116	The process id that detected a status change.
		1117
		1118	=item int rstatus [read-write]
		1119
		1120	The process exit/trace status caused by C<rpid> (see your systems
		1121	C<waitpid> and C<sys/wait.h> documentation for details).
		1122
1035	=back	1123	=back
1036		1124
1037	Example: try to exit cleanly on SIGINT and SIGTERM.	1125	Example: try to exit cleanly on SIGINT and SIGTERM.
1038		1126
1039	static void	1127	static void
…		…
1045	struct ev_signal signal_watcher;	1133	struct ev_signal signal_watcher;
1046	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1134	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1047	ev_signal_start (loop, &sigint_cb);	1135	ev_signal_start (loop, &sigint_cb);
1048		1136
1049		1137
		1138	=head2 C<ev_stat> - did the file attributes just change?
		1139
		1140	This watches a filesystem path for attribute changes. That is, it calls
		1141	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1142	compared to the last time, invoking the callback if it did.
		1143
		1144	The path does not need to exist: changing from "path exists" to "path does
		1145	not exist" is a status change like any other. The condition "path does
		1146	not exist" is signified by the C<st_nlink> field being zero (which is
		1147	otherwise always forced to be at least one) and all the other fields of
		1148	the stat buffer having unspecified contents.
		1149
		1150	Since there is no standard to do this, the portable implementation simply
		1151	calls C<stat (2)> regulalry on the path to see if it changed somehow. You
		1152	can specify a recommended polling interval for this case. If you specify
		1153	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1154	unspecified default> value will be used (which you can expect to be around
		1155	five seconds, although this might change dynamically). Libev will also
		1156	impose a minimum interval which is currently around C<0.1>, but thats
		1157	usually overkill.
		1158
		1159	This watcher type is not meant for massive numbers of stat watchers,
		1160	as even with OS-supported change notifications, this can be
		1161	resource-intensive.
		1162
		1163	At the time of this writing, no specific OS backends are implemented, but
		1164	if demand increases, at least a kqueue and inotify backend will be added.
		1165
		1166	=over 4
		1167
		1168	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
		1169
		1170	=item ev_stat_set (ev_stat , const char path, ev_tstamp interval)
		1171
		1172	Configures the watcher to wait for status changes of the given
		1173	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1174	be detected and should normally be specified as C<0> to let libev choose
		1175	a suitable value. The memory pointed to by C<path> must point to the same
		1176	path for as long as the watcher is active.
		1177
		1178	The callback will be receive C<EV_STAT> when a change was detected,
		1179	relative to the attributes at the time the watcher was started (or the
		1180	last change was detected).
		1181
		1182	=item ev_stat_stat (ev_stat *)
		1183
		1184	Updates the stat buffer immediately with new values. If you change the
		1185	watched path in your callback, you could call this fucntion to avoid
		1186	detecting this change (while introducing a race condition). Can also be
		1187	useful simply to find out the new values.
		1188
		1189	=item ev_statdata attr [read-only]
		1190
		1191	The most-recently detected attributes of the file. Although the type is of
		1192	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1193	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1194	was some error while C<stat>ing the file.
		1195
		1196	=item ev_statdata prev [read-only]
		1197
		1198	The previous attributes of the file. The callback gets invoked whenever
		1199	C<prev> != C<attr>.
		1200
		1201	=item ev_tstamp interval [read-only]
		1202
		1203	The specified interval.
		1204
		1205	=item const char *path [read-only]
		1206
		1207	The filesystem path that is being watched.
		1208
		1209	=back
		1210
		1211	Example: Watch C</etc/passwd> for attribute changes.
		1212
		1213	static void
		1214	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1215	{
		1216	/* /etc/passwd changed in some way */
		1217	if (w->attr.st_nlink)
		1218	{
		1219	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1220	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1221	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1222	}
		1223	else
		1224	/* you shalt not abuse printf for puts */
		1225	puts ("wow, /etc/passwd is not there, expect problems. "
		1226	"if this is windows, they already arrived\n");
		1227	}
		1228
		1229	...
		1230	ev_stat passwd;
		1231
		1232	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1233	ev_stat_start (loop, &passwd);
		1234
		1235
1050	=head2 C<ev_idle> - when you've got nothing better to do	1236	=head2 C<ev_idle> - when you've got nothing better to do...
1051		1237
1052	Idle watchers trigger events when there are no other events are pending	1238	Idle watchers trigger events when there are no other events are pending
1053	(prepare, check and other idle watchers do not count). That is, as long	1239	(prepare, check and other idle watchers do not count). That is, as long
1054	as your process is busy handling sockets or timeouts (or even signals,	1240	as your process is busy handling sockets or timeouts (or even signals,
1055	imagine) it will not be triggered. But when your process is idle all idle	1241	imagine) it will not be triggered. But when your process is idle all idle
…		…
1089	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1275	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1090	ev_idle_init (idle_watcher, idle_cb);	1276	ev_idle_init (idle_watcher, idle_cb);
1091	ev_idle_start (loop, idle_cb);	1277	ev_idle_start (loop, idle_cb);
1092		1278
1093		1279
1094	=head2 C<ev_prepare> and C<ev_check> - customise your event loop	1280	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1095		1281
1096	Prepare and check watchers are usually (but not always) used in tandem:	1282	Prepare and check watchers are usually (but not always) used in tandem:
1097	prepare watchers get invoked before the process blocks and check watchers	1283	prepare watchers get invoked before the process blocks and check watchers
1098	afterwards.	1284	afterwards.
1099		1285
		1286	You I<must not> call C<ev_loop> or similar functions that enter
		1287	the current event loop from either C<ev_prepare> or C<ev_check>
		1288	watchers. Other loops than the current one are fine, however. The
		1289	rationale behind this is that you do not need to check for recursion in
		1290	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
		1291	C<ev_check> so if you have one watcher of each kind they will always be
		1292	called in pairs bracketing the blocking call.
		1293
1100	Their main purpose is to integrate other event mechanisms into libev and	1294	Their main purpose is to integrate other event mechanisms into libev and
1101	their use is somewhat advanced. This could be used, for example, to track	1295	their use is somewhat advanced. This could be used, for example, to track
1102	variable changes, implement your own watchers, integrate net-snmp or a	1296	variable changes, implement your own watchers, integrate net-snmp or a
1103	coroutine library and lots more.	1297	coroutine library and lots more. They are also occasionally useful if
		1298	you cache some data and want to flush it before blocking (for example,
		1299	in X programs you might want to do an C<XFlush ()> in an C<ev_prepare>
		1300	watcher).
1104		1301
1105	This is done by examining in each prepare call which file descriptors need	1302	This is done by examining in each prepare call which file descriptors need
1106	to be watched by the other library, registering C<ev_io> watchers for	1303	to be watched by the other library, registering C<ev_io> watchers for
1107	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1304	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1108	provide just this functionality). Then, in the check watcher you check for	1305	provide just this functionality). Then, in the check watcher you check for
…		…
1130	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1327	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1131	macros, but using them is utterly, utterly and completely pointless.	1328	macros, but using them is utterly, utterly and completely pointless.
1132		1329
1133	=back	1330	=back
1134		1331
1135	Example: TODO.	1332	Example: To include a library such as adns, you would add IO watchers
		1333	and a timeout watcher in a prepare handler, as required by libadns, and
		1334	in a check watcher, destroy them and call into libadns. What follows is
		1335	pseudo-code only of course:
1136		1336
		1337	static ev_io iow [nfd];
		1338	static ev_timer tw;
1137		1339
		1340	static void
		1341	io_cb (ev_loop loop, ev_io w, int revents)
		1342	{
		1343	// set the relevant poll flags
		1344	// could also call adns_processreadable etc. here
		1345	struct pollfd fd = (struct pollfd )w->data;
		1346	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1347	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1348	}
		1349
		1350	// create io watchers for each fd and a timer before blocking
		1351	static void
		1352	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1353	{
		1354	int timeout = 3600000;truct pollfd fds [nfd];
		1355	// actual code will need to loop here and realloc etc.
		1356	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1357
		1358	/* the callback is illegal, but won't be called as we stop during check */
		1359	ev_timer_init (&tw, 0, timeout * 1e-3);
		1360	ev_timer_start (loop, &tw);
		1361
		1362	// create on ev_io per pollfd
		1363	for (int i = 0; i < nfd; ++i)
		1364	{
		1365	ev_io_init (iow + i, io_cb, fds [i].fd,
		1366	((fds [i].events & POLLIN ? EV_READ : 0)
		1367	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1368
		1369	fds [i].revents = 0;
		1370	iow [i].data = fds + i;
		1371	ev_io_start (loop, iow + i);
		1372	}
		1373	}
		1374
		1375	// stop all watchers after blocking
		1376	static void
		1377	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1378	{
		1379	ev_timer_stop (loop, &tw);
		1380
		1381	for (int i = 0; i < nfd; ++i)
		1382	ev_io_stop (loop, iow + i);
		1383
		1384	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1385	}
		1386
		1387
1138	=head2 C<ev_embed> - when one backend isn't enough	1388	=head2 C<ev_embed> - when one backend isn't enough...
1139		1389
1140	This is a rather advanced watcher type that lets you embed one event loop	1390	This is a rather advanced watcher type that lets you embed one event loop
1141	into another (currently only C<ev_io> events are supported in the embedded	1391	into another (currently only C<ev_io> events are supported in the embedded
1142	loop, other types of watchers might be handled in a delayed or incorrect	1392	loop, other types of watchers might be handled in a delayed or incorrect
1143	fashion and must not be used).	1393	fashion and must not be used).
…		…
1221		1471
1222	Make a single, non-blocking sweep over the embedded loop. This works	1472	Make a single, non-blocking sweep over the embedded loop. This works
1223	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1473	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1224	apropriate way for embedded loops.	1474	apropriate way for embedded loops.
1225		1475
		1476	=item struct ev_loop *loop [read-only]
		1477
		1478	The embedded event loop.
		1479
		1480	=back
		1481
		1482
		1483	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1484
		1485	Fork watchers are called when a C<fork ()> was detected (usually because
		1486	whoever is a good citizen cared to tell libev about it by calling
		1487	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1488	event loop blocks next and before C<ev_check> watchers are being called,
		1489	and only in the child after the fork. If whoever good citizen calling
		1490	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1491	handlers will be invoked, too, of course.
		1492
		1493	=over 4
		1494
		1495	=item ev_fork_init (ev_signal *, callback)
		1496
		1497	Initialises and configures the fork watcher - it has no parameters of any
		1498	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1499	believe me.
		1500
1226	=back	1501	=back
1227		1502
1228		1503
1229	=head1 OTHER FUNCTIONS	1504	=head1 OTHER FUNCTIONS
1230		1505
…		…
1310		1585
1311	=back	1586	=back
1312		1587
1313	=head1 C++ SUPPORT	1588	=head1 C++ SUPPORT
1314		1589
1315	TBD.	1590	Libev comes with some simplistic wrapper classes for C++ that mainly allow
		1591	you to use some convinience methods to start/stop watchers and also change
		1592	the callback model to a model using method callbacks on objects.
		1593
		1594	To use it,
		1595
		1596	#include <ev++.h>
		1597
		1598	(it is not installed by default). This automatically includes F<ev.h>
		1599	and puts all of its definitions (many of them macros) into the global
		1600	namespace. All C++ specific things are put into the C<ev> namespace.
		1601
		1602	It should support all the same embedding options as F<ev.h>, most notably
		1603	C<EV_MULTIPLICITY>.
		1604
		1605	Here is a list of things available in the C<ev> namespace:
		1606
		1607	=over 4
		1608
		1609	=item C<ev::READ>, C<ev::WRITE> etc.
		1610
		1611	These are just enum values with the same values as the C<EV_READ> etc.
		1612	macros from F<ev.h>.
		1613
		1614	=item C<ev::tstamp>, C<ev::now>
		1615
		1616	Aliases to the same types/functions as with the C<ev_> prefix.
		1617
		1618	=item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc.
		1619
		1620	For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of
		1621	the same name in the C<ev> namespace, with the exception of C<ev_signal>
		1622	which is called C<ev::sig> to avoid clashes with the C<signal> macro
		1623	defines by many implementations.
		1624
		1625	All of those classes have these methods:
		1626
		1627	=over 4
		1628
		1629	=item ev::TYPE::TYPE (object , object::method )
		1630
		1631	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)
		1632
		1633	=item ev::TYPE::~TYPE
		1634
		1635	The constructor takes a pointer to an object and a method pointer to
		1636	the event handler callback to call in this class. The constructor calls
		1637	C<ev_init> for you, which means you have to call the C<set> method
		1638	before starting it. If you do not specify a loop then the constructor
		1639	automatically associates the default loop with this watcher.
		1640
		1641	The destructor automatically stops the watcher if it is active.
		1642
		1643	=item w->set (struct ev_loop *)
		1644
		1645	Associates a different C<struct ev_loop> with this watcher. You can only
		1646	do this when the watcher is inactive (and not pending either).
		1647
		1648	=item w->set ([args])
		1649
		1650	Basically the same as C<ev_TYPE_set>, with the same args. Must be
		1651	called at least once. Unlike the C counterpart, an active watcher gets
		1652	automatically stopped and restarted.
		1653
		1654	=item w->start ()
		1655
		1656	Starts the watcher. Note that there is no C<loop> argument as the
		1657	constructor already takes the loop.
		1658
		1659	=item w->stop ()
		1660
		1661	Stops the watcher if it is active. Again, no C<loop> argument.
		1662
		1663	=item w->again () C<ev::timer>, C<ev::periodic> only
		1664
		1665	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
		1666	C<ev_TYPE_again> function.
		1667
		1668	=item w->sweep () C<ev::embed> only
		1669
		1670	Invokes C<ev_embed_sweep>.
		1671
		1672	=item w->update () C<ev::stat> only
		1673
		1674	Invokes C<ev_stat_stat>.
		1675
		1676	=back
		1677
		1678	=back
		1679
		1680	Example: Define a class with an IO and idle watcher, start one of them in
		1681	the constructor.
		1682
		1683	class myclass
		1684	{
		1685	ev_io io; void io_cb (ev::io &w, int revents);
		1686	ev_idle idle void idle_cb (ev::idle &w, int revents);
		1687
		1688	myclass ();
		1689	}
		1690
		1691	myclass::myclass (int fd)
		1692	: io (this, &myclass::io_cb),
		1693	idle (this, &myclass::idle_cb)
		1694	{
		1695	io.start (fd, ev::READ);
		1696	}
		1697
		1698
		1699	=head1 MACRO MAGIC
		1700
		1701	Libev can be compiled with a variety of options, the most fundemantal is
		1702	C<EV_MULTIPLICITY>. This option determines wether (most) functions and
		1703	callbacks have an initial C<struct ev_loop *> argument.
		1704
		1705	To make it easier to write programs that cope with either variant, the
		1706	following macros are defined:
		1707
		1708	=over 4
		1709
		1710	=item C<EV_A>, C<EV_A_>
		1711
		1712	This provides the loop I<argument> for functions, if one is required ("ev
		1713	loop argument"). The C<EV_A> form is used when this is the sole argument,
		1714	C<EV_A_> is used when other arguments are following. Example:
		1715
		1716	ev_unref (EV_A);
		1717	ev_timer_add (EV_A_ watcher);
		1718	ev_loop (EV_A_ 0);
		1719
		1720	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		1721	which is often provided by the following macro.
		1722
		1723	=item C<EV_P>, C<EV_P_>
		1724
		1725	This provides the loop I<parameter> for functions, if one is required ("ev
		1726	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		1727	C<EV_P_> is used when other parameters are following. Example:
		1728
		1729	// this is how ev_unref is being declared
		1730	static void ev_unref (EV_P);
		1731
		1732	// this is how you can declare your typical callback
		1733	static void cb (EV_P_ ev_timer *w, int revents)
		1734
		1735	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		1736	suitable for use with C<EV_A>.
		1737
		1738	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		1739
		1740	Similar to the other two macros, this gives you the value of the default
		1741	loop, if multiple loops are supported ("ev loop default").
		1742
		1743	=back
		1744
		1745	Example: Declare and initialise a check watcher, working regardless of
		1746	wether multiple loops are supported or not.
		1747
		1748	static void
		1749	check_cb (EV_P_ ev_timer *w, int revents)
		1750	{
		1751	ev_check_stop (EV_A_ w);
		1752	}
		1753
		1754	ev_check check;
		1755	ev_check_init (&check, check_cb);
		1756	ev_check_start (EV_DEFAULT_ &check);
		1757	ev_loop (EV_DEFAULT_ 0);
		1758
		1759
		1760	=head1 EMBEDDING
		1761
		1762	Libev can (and often is) directly embedded into host
		1763	applications. Examples of applications that embed it include the Deliantra
		1764	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
		1765	and rxvt-unicode.
		1766
		1767	The goal is to enable you to just copy the neecssary files into your
		1768	source directory without having to change even a single line in them, so
		1769	you can easily upgrade by simply copying (or having a checked-out copy of
		1770	libev somewhere in your source tree).
		1771
		1772	=head2 FILESETS
		1773
		1774	Depending on what features you need you need to include one or more sets of files
		1775	in your app.
		1776
		1777	=head3 CORE EVENT LOOP
		1778
		1779	To include only the libev core (all the C<ev_*> functions), with manual
		1780	configuration (no autoconf):
		1781
		1782	#define EV_STANDALONE 1
		1783	#include "ev.c"
		1784
		1785	This will automatically include F<ev.h>, too, and should be done in a
		1786	single C source file only to provide the function implementations. To use
		1787	it, do the same for F<ev.h> in all files wishing to use this API (best
		1788	done by writing a wrapper around F<ev.h> that you can include instead and
		1789	where you can put other configuration options):
		1790
		1791	#define EV_STANDALONE 1
		1792	#include "ev.h"
		1793
		1794	Both header files and implementation files can be compiled with a C++
		1795	compiler (at least, thats a stated goal, and breakage will be treated
		1796	as a bug).
		1797
		1798	You need the following files in your source tree, or in a directory
		1799	in your include path (e.g. in libev/ when using -Ilibev):
		1800
		1801	ev.h
		1802	ev.c
		1803	ev_vars.h
		1804	ev_wrap.h
		1805
		1806	ev_win32.c required on win32 platforms only
		1807
		1808	ev_select.c only when select backend is enabled (which is by default)
		1809	ev_poll.c only when poll backend is enabled (disabled by default)
		1810	ev_epoll.c only when the epoll backend is enabled (disabled by default)
		1811	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		1812	ev_port.c only when the solaris port backend is enabled (disabled by default)
		1813
		1814	F<ev.c> includes the backend files directly when enabled, so you only need
		1815	to compile this single file.
		1816
		1817	=head3 LIBEVENT COMPATIBILITY API
		1818
		1819	To include the libevent compatibility API, also include:
		1820
		1821	#include "event.c"
		1822
		1823	in the file including F<ev.c>, and:
		1824
		1825	#include "event.h"
		1826
		1827	in the files that want to use the libevent API. This also includes F<ev.h>.
		1828
		1829	You need the following additional files for this:
		1830
		1831	event.h
		1832	event.c
		1833
		1834	=head3 AUTOCONF SUPPORT
		1835
		1836	Instead of using C<EV_STANDALONE=1> and providing your config in
		1837	whatever way you want, you can also C<m4_include([libev.m4])> in your
		1838	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
		1839	include F<config.h> and configure itself accordingly.
		1840
		1841	For this of course you need the m4 file:
		1842
		1843	libev.m4
		1844
		1845	=head2 PREPROCESSOR SYMBOLS/MACROS
		1846
		1847	Libev can be configured via a variety of preprocessor symbols you have to define
		1848	before including any of its files. The default is not to build for multiplicity
		1849	and only include the select backend.
		1850
		1851	=over 4
		1852
		1853	=item EV_STANDALONE
		1854
		1855	Must always be C<1> if you do not use autoconf configuration, which
		1856	keeps libev from including F<config.h>, and it also defines dummy
		1857	implementations for some libevent functions (such as logging, which is not
		1858	supported). It will also not define any of the structs usually found in
		1859	F<event.h> that are not directly supported by the libev core alone.
		1860
		1861	=item EV_USE_MONOTONIC
		1862
		1863	If defined to be C<1>, libev will try to detect the availability of the
		1864	monotonic clock option at both compiletime and runtime. Otherwise no use
		1865	of the monotonic clock option will be attempted. If you enable this, you
		1866	usually have to link against librt or something similar. Enabling it when
		1867	the functionality isn't available is safe, though, althoguh you have
		1868	to make sure you link against any libraries where the C<clock_gettime>
		1869	function is hiding in (often F<-lrt>).
		1870
		1871	=item EV_USE_REALTIME
		1872
		1873	If defined to be C<1>, libev will try to detect the availability of the
		1874	realtime clock option at compiletime (and assume its availability at
		1875	runtime if successful). Otherwise no use of the realtime clock option will
		1876	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
		1877	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries
		1878	in the description of C<EV_USE_MONOTONIC>, though.
		1879
		1880	=item EV_USE_SELECT
		1881
		1882	If undefined or defined to be C<1>, libev will compile in support for the
		1883	C<select>(2) backend. No attempt at autodetection will be done: if no
		1884	other method takes over, select will be it. Otherwise the select backend
		1885	will not be compiled in.
		1886
		1887	=item EV_SELECT_USE_FD_SET
		1888
		1889	If defined to C<1>, then the select backend will use the system C<fd_set>
		1890	structure. This is useful if libev doesn't compile due to a missing
		1891	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on
		1892	exotic systems. This usually limits the range of file descriptors to some
		1893	low limit such as 1024 or might have other limitations (winsocket only
		1894	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
		1895	influence the size of the C<fd_set> used.
		1896
		1897	=item EV_SELECT_IS_WINSOCKET
		1898
		1899	When defined to C<1>, the select backend will assume that
		1900	select/socket/connect etc. don't understand file descriptors but
		1901	wants osf handles on win32 (this is the case when the select to
		1902	be used is the winsock select). This means that it will call
		1903	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
		1904	it is assumed that all these functions actually work on fds, even
		1905	on win32. Should not be defined on non-win32 platforms.
		1906
		1907	=item EV_USE_POLL
		1908
		1909	If defined to be C<1>, libev will compile in support for the C<poll>(2)
		1910	backend. Otherwise it will be enabled on non-win32 platforms. It
		1911	takes precedence over select.
		1912
		1913	=item EV_USE_EPOLL
		1914
		1915	If defined to be C<1>, libev will compile in support for the Linux
		1916	C<epoll>(7) backend. Its availability will be detected at runtime,
		1917	otherwise another method will be used as fallback. This is the
		1918	preferred backend for GNU/Linux systems.
		1919
		1920	=item EV_USE_KQUEUE
		1921
		1922	If defined to be C<1>, libev will compile in support for the BSD style
		1923	C<kqueue>(2) backend. Its actual availability will be detected at runtime,
		1924	otherwise another method will be used as fallback. This is the preferred
		1925	backend for BSD and BSD-like systems, although on most BSDs kqueue only
		1926	supports some types of fds correctly (the only platform we found that
		1927	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		1928	not be used unless explicitly requested. The best way to use it is to find
		1929	out whether kqueue supports your type of fd properly and use an embedded
		1930	kqueue loop.
		1931
		1932	=item EV_USE_PORT
		1933
		1934	If defined to be C<1>, libev will compile in support for the Solaris
		1935	10 port style backend. Its availability will be detected at runtime,
		1936	otherwise another method will be used as fallback. This is the preferred
		1937	backend for Solaris 10 systems.
		1938
		1939	=item EV_USE_DEVPOLL
		1940
		1941	reserved for future expansion, works like the USE symbols above.
		1942
		1943	=item EV_H
		1944
		1945	The name of the F<ev.h> header file used to include it. The default if
		1946	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
		1947	can be used to virtually rename the F<ev.h> header file in case of conflicts.
		1948
		1949	=item EV_CONFIG_H
		1950
		1951	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
		1952	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
		1953	C<EV_H>, above.
		1954
		1955	=item EV_EVENT_H
		1956
		1957	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
		1958	of how the F<event.h> header can be found.
		1959
		1960	=item EV_PROTOTYPES
		1961
		1962	If defined to be C<0>, then F<ev.h> will not define any function
		1963	prototypes, but still define all the structs and other symbols. This is
		1964	occasionally useful if you want to provide your own wrapper functions
		1965	around libev functions.
		1966
		1967	=item EV_MULTIPLICITY
		1968
		1969	If undefined or defined to C<1>, then all event-loop-specific functions
		1970	will have the C<struct ev_loop *> as first argument, and you can create
		1971	additional independent event loops. Otherwise there will be no support
		1972	for multiple event loops and there is no first event loop pointer
		1973	argument. Instead, all functions act on the single default loop.
		1974
		1975	=item EV_PERIODIC_ENABLE
		1976
		1977	If undefined or defined to be C<1>, then periodic timers are supported. If
		1978	defined to be C<0>, then they are not. Disabling them saves a few kB of
		1979	code.
		1980
		1981	=item EV_EMBED_ENABLE
		1982
		1983	If undefined or defined to be C<1>, then embed watchers are supported. If
		1984	defined to be C<0>, then they are not.
		1985
		1986	=item EV_STAT_ENABLE
		1987
		1988	If undefined or defined to be C<1>, then stat watchers are supported. If
		1989	defined to be C<0>, then they are not.
		1990
		1991	=item EV_FORK_ENABLE
		1992
		1993	If undefined or defined to be C<1>, then fork watchers are supported. If
		1994	defined to be C<0>, then they are not.
		1995
		1996	=item EV_MINIMAL
		1997
		1998	If you need to shave off some kilobytes of code at the expense of some
		1999	speed, define this symbol to C<1>. Currently only used for gcc to override
		2000	some inlining decisions, saves roughly 30% codesize of amd64.
		2001
		2002	=item EV_COMMON
		2003
		2004	By default, all watchers have a C<void *data> member. By redefining
		2005	this macro to a something else you can include more and other types of
		2006	members. You have to define it each time you include one of the files,
		2007	though, and it must be identical each time.
		2008
		2009	For example, the perl EV module uses something like this:
		2010
		2011	#define EV_COMMON \
		2012	SV self; / contains this struct */ \
		2013	SV cb_sv, fh /* note no trailing ";" */
		2014
		2015	=item EV_CB_DECLARE (type)
		2016
		2017	=item EV_CB_INVOKE (watcher, revents)
		2018
		2019	=item ev_set_cb (ev, cb)
		2020
		2021	Can be used to change the callback member declaration in each watcher,
		2022	and the way callbacks are invoked and set. Must expand to a struct member
		2023	definition and a statement, respectively. See the F<ev.v> header file for
		2024	their default definitions. One possible use for overriding these is to
		2025	avoid the C<struct ev_loop *> as first argument in all cases, or to use
		2026	method calls instead of plain function calls in C++.
		2027
		2028	=head2 EXAMPLES
		2029
		2030	For a real-world example of a program the includes libev
		2031	verbatim, you can have a look at the EV perl module
		2032	(L<http://software.schmorp.de/pkg/EV.html>). It has the libev files in
		2033	the F<libev/> subdirectory and includes them in the F<EV/EVAPI.h> (public
		2034	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
		2035	will be compiled. It is pretty complex because it provides its own header
		2036	file.
		2037
		2038	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
		2039	that everybody includes and which overrides some autoconf choices:
		2040
		2041	#define EV_USE_POLL 0
		2042	#define EV_MULTIPLICITY 0
		2043	#define EV_PERIODICS 0
		2044	#define EV_CONFIG_H <config.h>
		2045
		2046	#include "ev++.h"
		2047
		2048	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
		2049
		2050	#include "ev_cpp.h"
		2051	#include "ev.c"
		2052
		2053
		2054	=head1 COMPLEXITIES
		2055
		2056	In this section the complexities of (many of) the algorithms used inside
		2057	libev will be explained. For complexity discussions about backends see the
		2058	documentation for C<ev_default_init>.
		2059
		2060	=over 4
		2061
		2062	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
		2063
		2064	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
		2065
		2066	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
		2067
		2068	=item Stopping check/prepare/idle watchers: O(1)
		2069
		2070	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))
		2071
		2072	=item Finding the next timer per loop iteration: O(1)
		2073
		2074	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
		2075
		2076	=item Activating one watcher: O(1)
		2077
		2078	=back
		2079
1316		2080
1317	=head1 AUTHOR	2081	=head1 AUTHOR
1318		2082
1319	Marc Lehmann <libev@schmorp.de>.	2083	Marc Lehmann <libev@schmorp.de>.
1320		2084

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Comparing libev/ev.pod (file contents): Revision 1.37 by root, Sat Nov 24 07:20:43 2007 UTC vs. Revision 1.50 by root, Tue Nov 27 10:59:11 2007 UTC

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Revision 1.37 by root, Sat Nov 24 07:20:43 2007 UTC vs.
Revision 1.50 by root, Tue Nov 27 10:59:11 2007 UTC