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

Comparing libev/ev.pod (file contents):
Revision 1.40 by root, Sat Nov 24 10:15:16 2007 UTC vs.
Revision 1.52 by root, Tue Nov 27 19:41:52 2007 UTC

…		…
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		52
53
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.
58		57
…		…
116	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	115	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
117	recommended ones.	116	recommended ones.
118		117
119	See the description of C<ev_embed> watchers for more info.	118	See the description of C<ev_embed> watchers for more info.
120		119
121	=item ev_set_allocator (void (cb)(void *ptr, long size))	120	=item ev_set_allocator (void (cb)(void *ptr, size_t size))
122		121
123	Sets the allocation function to use (the prototype is similar to the	122	Sets the allocation function to use (the prototype and semantics are
124	realloc C function, the semantics are identical). It is used to allocate	123	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	124	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	125	allocated, the library might abort or take some potentially destructive
127	destructive action. The default is your system realloc function.	126	action. The default is your system realloc function.
128		127
129	You could override this function in high-availability programs to, say,	128	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,	129	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.	130	or even to sleep a while and retry until some memory is available.
132		131
133	Example: replace the libev allocator with one that waits a bit and then	132	Example: replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	133	retries: better than mine).
135		134
136	static void *	135	static void *
137	persistent_realloc (void *ptr, long size)	136	persistent_realloc (void *ptr, size_t size)
138	{	137	{
139	for (;;)	138	for (;;)
140	{	139	{
141	void *newptr = realloc (ptr, size);	140	void *newptr = realloc (ptr, size);
142		141
…		…
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)
…		…
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
…		…
1392		1667
1393	=item w->sweep () C<ev::embed> only	1668	=item w->sweep () C<ev::embed> only
1394		1669
1395	Invokes C<ev_embed_sweep>.	1670	Invokes C<ev_embed_sweep>.
1396		1671
		1672	=item w->update () C<ev::stat> only
		1673
		1674	Invokes C<ev_stat_stat>.
		1675
1397	=back	1676	=back
1398		1677
1399	=back	1678	=back
1400		1679
1401	Example: Define a class with an IO and idle watcher, start one of them in	1680	Example: Define a class with an IO and idle watcher, start one of them in
…		…
1414	idle (this, &myclass::idle_cb)	1693	idle (this, &myclass::idle_cb)
1415	{	1694	{
1416	io.start (fd, ev::READ);	1695	io.start (fd, ev::READ);
1417	}	1696	}
1418		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
1419	=head1 EMBEDDING	1760	=head1 EMBEDDING
1420		1761
1421	Libev can (and often is) directly embedded into host	1762	Libev can (and often is) directly embedded into host
1422	applications. Examples of applications that embed it include the Deliantra	1763	applications. Examples of applications that embed it include the Deliantra
1423	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	1764	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
…		…
1462	ev_vars.h	1803	ev_vars.h
1463	ev_wrap.h	1804	ev_wrap.h
1464		1805
1465	ev_win32.c required on win32 platforms only	1806	ev_win32.c required on win32 platforms only
1466		1807
1467	ev_select.c only when select backend is enabled (which is is by default)	1808	ev_select.c only when select backend is enabled (which is by default)
1468	ev_poll.c only when poll backend is enabled (disabled by default)	1809	ev_poll.c only when poll backend is enabled (disabled by default)
1469	ev_epoll.c only when the epoll backend is enabled (disabled by default)	1810	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1470	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	1811	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1471	ev_port.c only when the solaris port backend is enabled (disabled by default)	1812	ev_port.c only when the solaris port backend is enabled (disabled by default)
1472		1813
1473	F<ev.c> includes the backend files directly when enabled, so you only need	1814	F<ev.c> includes the backend files directly when enabled, so you only need
1474	to compile a single file.	1815	to compile this single file.
1475		1816
1476	=head3 LIBEVENT COMPATIBILITY API	1817	=head3 LIBEVENT COMPATIBILITY API
1477		1818
1478	To include the libevent compatibility API, also include:	1819	To include the libevent compatibility API, also include:
1479		1820
…		…
1492		1833
1493	=head3 AUTOCONF SUPPORT	1834	=head3 AUTOCONF SUPPORT
1494		1835
1495	Instead of using C<EV_STANDALONE=1> and providing your config in	1836	Instead of using C<EV_STANDALONE=1> and providing your config in
1496	whatever way you want, you can also C<m4_include([libev.m4])> in your	1837	whatever way you want, you can also C<m4_include([libev.m4])> in your
1497	F<configure.ac> and leave C<EV_STANDALONE> off. F<ev.c> will then include	1838	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
1498	F<config.h> and configure itself accordingly.	1839	include F<config.h> and configure itself accordingly.
1499		1840
1500	For this of course you need the m4 file:	1841	For this of course you need the m4 file:
1501		1842
1502	libev.m4	1843	libev.m4
1503		1844
…		…
1583	otherwise another method will be used as fallback. This is the preferred	1924	otherwise another method will be used as fallback. This is the preferred
1584	backend for BSD and BSD-like systems, although on most BSDs kqueue only	1925	backend for BSD and BSD-like systems, although on most BSDs kqueue only
1585	supports some types of fds correctly (the only platform we found that	1926	supports some types of fds correctly (the only platform we found that
1586	supports ptys for example was NetBSD), so kqueue might be compiled in, but	1927	supports ptys for example was NetBSD), so kqueue might be compiled in, but
1587	not be used unless explicitly requested. The best way to use it is to find	1928	not be used unless explicitly requested. The best way to use it is to find
1588	out wether kqueue supports your type of fd properly and use an embedded	1929	out whether kqueue supports your type of fd properly and use an embedded
1589	kqueue loop.	1930	kqueue loop.
1590		1931
1591	=item EV_USE_PORT	1932	=item EV_USE_PORT
1592		1933
1593	If defined to be C<1>, libev will compile in support for the Solaris	1934	If defined to be C<1>, libev will compile in support for the Solaris
…		…
1629	will have the C<struct ev_loop *> as first argument, and you can create	1970	will have the C<struct ev_loop *> as first argument, and you can create
1630	additional independent event loops. Otherwise there will be no support	1971	additional independent event loops. Otherwise there will be no support
1631	for multiple event loops and there is no first event loop pointer	1972	for multiple event loops and there is no first event loop pointer
1632	argument. Instead, all functions act on the single default loop.	1973	argument. Instead, all functions act on the single default loop.
1633		1974
1634	=item EV_PERIODICS	1975	=item EV_PERIODIC_ENABLE
1635		1976
1636	If undefined or defined to be C<1>, then periodic timers are supported,	1977	If undefined or defined to be C<1>, then periodic timers are supported. If
1637	otherwise not. This saves a few kb of code.	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_PID_HASHSIZE
		2003
		2004	C<ev_child> watchers use a small hash table to distribute workload by
		2005	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2006	than enough. If you need to manage thousands of children you might want to
		2007	increase this value.
1638		2008
1639	=item EV_COMMON	2009	=item EV_COMMON
1640		2010
1641	By default, all watchers have a C<void *data> member. By redefining	2011	By default, all watchers have a C<void *data> member. By redefining
1642	this macro to a something else you can include more and other types of	2012	this macro to a something else you can include more and other types of
…		…
1647		2017
1648	#define EV_COMMON \	2018	#define EV_COMMON \
1649	SV self; / contains this struct */ \	2019	SV self; / contains this struct */ \
1650	SV cb_sv, fh /* note no trailing ";" */	2020	SV cb_sv, fh /* note no trailing ";" */
1651		2021
1652	=item EV_CB_DECLARE(type)	2022	=item EV_CB_DECLARE (type)
1653		2023
1654	=item EV_CB_INVOKE(watcher,revents)	2024	=item EV_CB_INVOKE (watcher, revents)
1655		2025
1656	=item ev_set_cb(ev,cb)	2026	=item ev_set_cb (ev, cb)
1657		2027
1658	Can be used to change the callback member declaration in each watcher,	2028	Can be used to change the callback member declaration in each watcher,
1659	and the way callbacks are invoked and set. Must expand to a struct member	2029	and the way callbacks are invoked and set. Must expand to a struct member
1660	definition and a statement, respectively. See the F<ev.v> header file for	2030	definition and a statement, respectively. See the F<ev.v> header file for
1661	their default definitions. One possible use for overriding these is to	2031	their default definitions. One possible use for overriding these is to
1662	avoid the ev_loop pointer as first argument in all cases, or to use method	2032	avoid the C<struct ev_loop *> as first argument in all cases, or to use
1663	calls instead of plain function calls in C++.	2033	method calls instead of plain function calls in C++.
1664		2034
1665	=head2 EXAMPLES	2035	=head2 EXAMPLES
1666		2036
1667	For a real-world example of a program the includes libev	2037	For a real-world example of a program the includes libev
1668	verbatim, you can have a look at the EV perl module	2038	verbatim, you can have a look at the EV perl module
…		…
1685	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2055	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
1686		2056
1687	#include "ev_cpp.h"	2057	#include "ev_cpp.h"
1688	#include "ev.c"	2058	#include "ev.c"
1689		2059
		2060
		2061	=head1 COMPLEXITIES
		2062
		2063	In this section the complexities of (many of) the algorithms used inside
		2064	libev will be explained. For complexity discussions about backends see the
		2065	documentation for C<ev_default_init>.
		2066
		2067	=over 4
		2068
		2069	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
		2070
		2071	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
		2072
		2073	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
		2074
		2075	=item Stopping check/prepare/idle watchers: O(1)
		2076
		2077	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))
		2078
		2079	=item Finding the next timer per loop iteration: O(1)
		2080
		2081	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
		2082
		2083	=item Activating one watcher: O(1)
		2084
		2085	=back
		2086
		2087
1690	=head1 AUTHOR	2088	=head1 AUTHOR
1691		2089
1692	Marc Lehmann <libev@schmorp.de>.	2090	Marc Lehmann <libev@schmorp.de>.
1693		2091

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Comparing libev/ev.pod (file contents): Revision 1.40 by root, Sat Nov 24 10:15:16 2007 UTC vs. Revision 1.52 by root, Tue Nov 27 19:41:52 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.40 by root, Sat Nov 24 10:15:16 2007 UTC vs.
Revision 1.52 by root, Tue Nov 27 19:41:52 2007 UTC