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

Comparing libev/ev.pod (file contents):
Revision 1.46 by root, Mon Nov 26 10:20:43 2007 UTC vs.
Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC

…		…
3	libev - a high performance full-featured event loop written in C	3	libev - a high performance full-featured event loop written in C
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
		8
		9	=head1 EXAMPLE PROGRAM
		10
		11	#include <ev.h>
		12
		13	ev_io stdin_watcher;
		14	ev_timer timeout_watcher;
		15
		16	/* called when data readable on stdin */
		17	static void
		18	stdin_cb (EV_P_ struct ev_io *w, int revents)
		19	{
		20	/* puts ("stdin ready"); */
		21	ev_io_stop (EV_A_ w); /* just a syntax example */
		22	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
		23	}
		24
		25	static void
		26	timeout_cb (EV_P_ struct ev_timer *w, int revents)
		27	{
		28	/* puts ("timeout"); */
		29	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
		30	}
		31
		32	int
		33	main (void)
		34	{
		35	struct ev_loop *loop = ev_default_loop (0);
		36
		37	/* initialise an io watcher, then start it */
		38	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);
		39	ev_io_start (loop, &stdin_watcher);
		40
		41	/* simple non-repeating 5.5 second timeout */
		42	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		43	ev_timer_start (loop, &timeout_watcher);
		44
		45	/* loop till timeout or data ready */
		46	ev_loop (loop, 0);
		47
		48	return 0;
		49	}
8		50
9	=head1 DESCRIPTION	51	=head1 DESCRIPTION
10		52
11	Libev is an event loop: you register interest in certain events (such as a	53	Libev is an event loop: you register interest in certain events (such as a
12	file descriptor being readable or a timeout occuring), and it will manage	54	file descriptor being readable or a timeout occuring), and it will manage
…		…
21	details of the event, and then hand it over to libev by I<starting> the	63	details of the event, and then hand it over to libev by I<starting> the
22	watcher.	64	watcher.
23		65
24	=head1 FEATURES	66	=head1 FEATURES
25		67
26	Libev supports select, poll, the linux-specific epoll and the bsd-specific	68	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
27	kqueue mechanisms for file descriptor events, relative timers, absolute	69	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
28	timers with customised rescheduling, signal events, process status change	70	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
29	events (related to SIGCHLD), and event watchers dealing with the event	71	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
30	loop mechanism itself (idle, prepare and check watchers). It also is quite	72	with customised rescheduling (C<ev_periodic>), synchronous signals
		73	(C<ev_signal>), process status change events (C<ev_child>), and event
		74	watchers dealing with the event loop mechanism itself (C<ev_idle>,
		75	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
		76	file watchers (C<ev_stat>) and even limited support for fork events
		77	(C<ev_fork>).
		78
		79	It also is quite fast (see this
31	fast (see this L<benchmark\|http://libev.schmorp.de/bench.html> comparing	80	L<benchmark\|http://libev.schmorp.de/bench.html> comparing it to libevent
32	it to libevent for example).	81	for example).
33		82
34	=head1 CONVENTIONS	83	=head1 CONVENTIONS
35		84
36	Libev is very configurable. In this manual the default configuration	85	Libev is very configurable. In this manual the default configuration will
37	will be described, which supports multiple event loops. For more info	86	be described, which supports multiple event loops. For more info about
38	about various configuration options please have a look at the file	87	various configuration options please have a look at B<EMBED> section in
39	F<README.embed> in the libev distribution. If libev was configured without	88	this manual. If libev was configured without support for multiple event
40	support for multiple event loops, then all functions taking an initial	89	loops, then all functions taking an initial argument of name C<loop>
41	argument of name C<loop> (which is always of type C<struct ev_loop *>)	90	(which is always of type C<struct ev_loop *>) will not have this argument.
42	will not have this argument.
43		91
44	=head1 TIME REPRESENTATION	92	=head1 TIME REPRESENTATION
45		93
46	Libev represents time as a single floating point number, representing the	94	Libev represents time as a single floating point number, representing the
47	(fractional) number of seconds since the (POSIX) epoch (somewhere near	95	(fractional) number of seconds since the (POSIX) epoch (somewhere near
48	the beginning of 1970, details are complicated, don't ask). This type is	96	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	97	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	98	to the C<double> type in C, and when you need to do any calculations on
51	it, you should treat it as such.	99	it, you should treat it as such.
52		100
53
54	=head1 GLOBAL FUNCTIONS	101	=head1 GLOBAL FUNCTIONS
55		102
56	These functions can be called anytime, even before initialising the	103	These functions can be called anytime, even before initialising the
57	library in any way.	104	library in any way.
58		105
…		…
77	Usually, it's a good idea to terminate if the major versions mismatch,	124	Usually, it's a good idea to terminate if the major versions mismatch,
78	as this indicates an incompatible change. Minor versions are usually	125	as this indicates an incompatible change. Minor versions are usually
79	compatible to older versions, so a larger minor version alone is usually	126	compatible to older versions, so a larger minor version alone is usually
80	not a problem.	127	not a problem.
81		128
82	Example: make sure we haven't accidentally been linked against the wrong	129	Example: Make sure we haven't accidentally been linked against the wrong
83	version:	130	version.
84		131
85	assert (("libev version mismatch",	132	assert (("libev version mismatch",
86	ev_version_major () == EV_VERSION_MAJOR	133	ev_version_major () == EV_VERSION_MAJOR
87	&& ev_version_minor () >= EV_VERSION_MINOR));	134	&& ev_version_minor () >= EV_VERSION_MINOR));
88		135
…		…
116	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	163	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
117	recommended ones.	164	recommended ones.
118		165
119	See the description of C<ev_embed> watchers for more info.	166	See the description of C<ev_embed> watchers for more info.
120		167
121	=item ev_set_allocator (void (cb)(void *ptr, long size))	168	=item ev_set_allocator (void (cb)(void *ptr, size_t size))
122		169
123	Sets the allocation function to use (the prototype is similar to the	170	Sets the allocation function to use (the prototype and semantics are
124	realloc C function, the semantics are identical). It is used to allocate	171	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	172	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	173	allocated, the library might abort or take some potentially destructive
127	destructive action. The default is your system realloc function.	174	action. The default is your system realloc function.
128		175
129	You could override this function in high-availability programs to, say,	176	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,	177	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.	178	or even to sleep a while and retry until some memory is available.
132		179
133	Example: replace the libev allocator with one that waits a bit and then	180	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	181	retries).
135		182
136	static void *	183	static void *
137	persistent_realloc (void *ptr, long size)	184	persistent_realloc (void *ptr, size_t size)
138	{	185	{
139	for (;;)	186	for (;;)
140	{	187	{
141	void *newptr = realloc (ptr, size);	188	void *newptr = realloc (ptr, size);
142		189
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	205	callback is set, then libev will expect it to remedy the sitution, no
159	matter what, when it returns. That is, libev will generally retry the	206	matter what, when it returns. That is, libev will generally retry the
160	requested operation, or, if the condition doesn't go away, do bad stuff	207	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	208	(such as abort).
162		209
163	Example: do the same thing as libev does internally:	210	Example: This is basically the same thing that libev does internally, too.
164		211
165	static void	212	static void
166	fatal_error (const char *msg)	213	fatal_error (const char *msg)
167	{	214	{
168	perror (msg);	215	perror (msg);
…		…
314	Similar to C<ev_default_loop>, but always creates a new event loop that is	361	Similar to C<ev_default_loop>, but always creates a new event loop that is
315	always distinct from the default loop. Unlike the default loop, it cannot	362	always distinct from the default loop. Unlike the default loop, it cannot
316	handle signal and child watchers, and attempts to do so will be greeted by	363	handle signal and child watchers, and attempts to do so will be greeted by
317	undefined behaviour (or a failed assertion if assertions are enabled).	364	undefined behaviour (or a failed assertion if assertions are enabled).
318		365
319	Example: try to create a event loop that uses epoll and nothing else.	366	Example: Try to create a event loop that uses epoll and nothing else.
320		367
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	368	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
322	if (!epoller)	369	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	370	fatal ("no epoll found here, maybe it hides under your chair");
324		371
…		…
423	Signals and child watchers are implemented as I/O watchers, and will	470	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	471	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	472	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	473	were used, return, otherwise continue with step *.
427		474
428	Example: queue some jobs and then loop until no events are outsanding	475	Example: Queue some jobs and then loop until no events are outsanding
429	anymore.	476	anymore.
430		477
431	... queue jobs here, make sure they register event watchers as long	478	... queue jobs here, make sure they register event watchers as long
432	... as they still have work to do (even an idle watcher will do..)	479	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	480	ev_loop (my_loop, 0);
…		…
453	visible to the libev user and should not keep C<ev_loop> from exiting if	500	visible to the libev user and should not keep C<ev_loop> from exiting if
454	no event watchers registered by it are active. It is also an excellent	501	no event watchers registered by it are active. It is also an excellent
455	way to do this for generic recurring timers or from within third-party	502	way to do this for generic recurring timers or from within third-party
456	libraries. Just remember to I<unref after start> and I<ref before stop>.	503	libraries. Just remember to I<unref after start> and I<ref before stop>.
457		504
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	505	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	506	running when nothing else is active.
460		507
461	struct dv_signal exitsig;	508	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	509	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	510	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	511	evf_unref (loop);
465		512
466	Example: for some weird reason, unregister the above signal handler again.	513	Example: For some weird reason, unregister the above signal handler again.
467		514
468	ev_ref (myloop);	515	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	516	ev_signal_stop (loop, &exitsig);
470		517
471	=back	518	=back
472		519
473		520
474	=head1 ANATOMY OF A WATCHER	521	=head1 ANATOMY OF A WATCHER
…		…
544	The signal specified in the C<ev_signal> watcher has been received by a thread.	591	The signal specified in the C<ev_signal> watcher has been received by a thread.
545		592
546	=item C<EV_CHILD>	593	=item C<EV_CHILD>
547		594
548	The pid specified in the C<ev_child> watcher has received a status change.	595	The pid specified in the C<ev_child> watcher has received a status change.
		596
		597	=item C<EV_STAT>
		598
		599	The path specified in the C<ev_stat> watcher changed its attributes somehow.
549		600
550	=item C<EV_IDLE>	601	=item C<EV_IDLE>
551		602
552	The C<ev_idle> watcher has determined that you have nothing better to do.	603	The C<ev_idle> watcher has determined that you have nothing better to do.
553		604
…		…
561	received events. Callbacks of both watcher types can start and stop as	612	received events. Callbacks of both watcher types can start and stop as
562	many watchers as they want, and all of them will be taken into account	613	many watchers as they want, and all of them will be taken into account
563	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	614	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
564	C<ev_loop> from blocking).	615	C<ev_loop> from blocking).
565		616
		617	=item C<EV_EMBED>
		618
		619	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		620
		621	=item C<EV_FORK>
		622
		623	The event loop has been resumed in the child process after fork (see
		624	C<ev_fork>).
		625
566	=item C<EV_ERROR>	626	=item C<EV_ERROR>
567		627
568	An unspecified error has occured, the watcher has been stopped. This might	628	An unspecified error has occured, the watcher has been stopped. This might
569	happen because the watcher could not be properly started because libev	629	happen because the watcher could not be properly started because libev
570	ran out of memory, a file descriptor was found to be closed or any other	630	ran out of memory, a file descriptor was found to be closed or any other
…		…
644	events but its callback has not yet been invoked). As long as a watcher	704	events but its callback has not yet been invoked). As long as a watcher
645	is pending (but not active) you must not call an init function on it (but	705	is pending (but not active) you must not call an init function on it (but
646	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	706	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to
647	libev (e.g. you cnanot C<free ()> it).	707	libev (e.g. you cnanot C<free ()> it).
648		708
649	=item callback = ev_cb (ev_TYPE *watcher)	709	=item callback ev_cb (ev_TYPE *watcher)
650		710
651	Returns the callback currently set on the watcher.	711	Returns the callback currently set on the watcher.
652		712
653	=item ev_cb_set (ev_TYPE *watcher, callback)	713	=item ev_cb_set (ev_TYPE *watcher, callback)
654		714
…		…
682	{	742	{
683	struct my_io w = (struct my_io )w_;	743	struct my_io w = (struct my_io )w_;
684	...	744	...
685	}	745	}
686		746
687	More interesting and less C-conformant ways of catsing your callback type	747	More interesting and less C-conformant ways of casting your callback type
688	have been omitted....	748	instead have been omitted.
		749
		750	Another common scenario is having some data structure with multiple
		751	watchers:
		752
		753	struct my_biggy
		754	{
		755	int some_data;
		756	ev_timer t1;
		757	ev_timer t2;
		758	}
		759
		760	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		761	you need to use C<offsetof>:
		762
		763	#include <stddef.h>
		764
		765	static void
		766	t1_cb (EV_P_ struct ev_timer *w, int revents)
		767	{
		768	struct my_biggy big = (struct my_biggy *
		769	(((char *)w) - offsetof (struct my_biggy, t1));
		770	}
		771
		772	static void
		773	t2_cb (EV_P_ struct ev_timer *w, int revents)
		774	{
		775	struct my_biggy big = (struct my_biggy *
		776	(((char *)w) - offsetof (struct my_biggy, t2));
		777	}
689		778
690		779
691	=head1 WATCHER TYPES	780	=head1 WATCHER TYPES
692		781
693	This section describes each watcher in detail, but will not repeat	782	This section describes each watcher in detail, but will not repeat
694	information given in the last section.	783	information given in the last section. Any initialisation/set macros,
		784	functions and members specific to the watcher type are explained.
		785
		786	Members are additionally marked with either I<[read-only]>, meaning that,
		787	while the watcher is active, you can look at the member and expect some
		788	sensible content, but you must not modify it (you can modify it while the
		789	watcher is stopped to your hearts content), or I<[read-write]>, which
		790	means you can expect it to have some sensible content while the watcher
		791	is active, but you can also modify it. Modifying it may not do something
		792	sensible or take immediate effect (or do anything at all), but libev will
		793	not crash or malfunction in any way.
695		794
696		795
697	=head2 C<ev_io> - is this file descriptor readable or writable?	796	=head2 C<ev_io> - is this file descriptor readable or writable?
698		797
699	I/O watchers check whether a file descriptor is readable or writable	798	I/O watchers check whether a file descriptor is readable or writable
…		…
742		841
743	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	842	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
744	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	843	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
745	C<EV_READ \| EV_WRITE> to receive the given events.	844	C<EV_READ \| EV_WRITE> to receive the given events.
746		845
		846	=item int fd [read-only]
		847
		848	The file descriptor being watched.
		849
		850	=item int events [read-only]
		851
		852	The events being watched.
		853
747	=back	854	=back
748		855
749	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	856	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
750	readable, but only once. Since it is likely line-buffered, you could	857	readable, but only once. Since it is likely line-buffered, you could
751	attempt to read a whole line in the callback:	858	attempt to read a whole line in the callback.
752		859
753	static void	860	static void
754	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	861	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
755	{	862	{
756	ev_io_stop (loop, w);	863	ev_io_stop (loop, w);
…		…
814		921
815	If the timer is repeating, either start it if necessary (with the repeat	922	If the timer is repeating, either start it if necessary (with the repeat
816	value), or reset the running timer to the repeat value.	923	value), or reset the running timer to the repeat value.
817		924
818	This sounds a bit complicated, but here is a useful and typical	925	This sounds a bit complicated, but here is a useful and typical
819	example: Imagine you have a tcp connection and you want a so-called idle	926	example: Imagine you have a tcp connection and you want a so-called
820	timeout, that is, you want to be called when there have been, say, 60	927	idle timeout, that is, you want to be called when there have been,
821	seconds of inactivity on the socket. The easiest way to do this is to	928	say, 60 seconds of inactivity on the socket. The easiest way to do
822	configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each	929	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling
823	time you successfully read or write some data. If you go into an idle	930	C<ev_timer_again> each time you successfully read or write some data. If
824	state where you do not expect data to travel on the socket, you can stop	931	you go into an idle state where you do not expect data to travel on the
825	the timer, and again will automatically restart it if need be.	932	socket, you can stop the timer, and again will automatically restart it if
		933	need be.
		934
		935	You can also ignore the C<after> value and C<ev_timer_start> altogether
		936	and only ever use the C<repeat> value:
		937
		938	ev_timer_init (timer, callback, 0., 5.);
		939	ev_timer_again (loop, timer);
		940	...
		941	timer->again = 17.;
		942	ev_timer_again (loop, timer);
		943	...
		944	timer->again = 10.;
		945	ev_timer_again (loop, timer);
		946
		947	This is more efficient then stopping/starting the timer eahc time you want
		948	to modify its timeout value.
		949
		950	=item ev_tstamp repeat [read-write]
		951
		952	The current C<repeat> value. Will be used each time the watcher times out
		953	or C<ev_timer_again> is called and determines the next timeout (if any),
		954	which is also when any modifications are taken into account.
826		955
827	=back	956	=back
828		957
829	Example: create a timer that fires after 60 seconds.	958	Example: Create a timer that fires after 60 seconds.
830		959
831	static void	960	static void
832	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	961	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
833	{	962	{
834	.. one minute over, w is actually stopped right here	963	.. one minute over, w is actually stopped right here
…		…
836		965
837	struct ev_timer mytimer;	966	struct ev_timer mytimer;
838	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	967	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
839	ev_timer_start (loop, &mytimer);	968	ev_timer_start (loop, &mytimer);
840		969
841	Example: create a timeout timer that times out after 10 seconds of	970	Example: Create a timeout timer that times out after 10 seconds of
842	inactivity.	971	inactivity.
843		972
844	static void	973	static void
845	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	974	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
846	{	975	{
…		…
957	Simply stops and restarts the periodic watcher again. This is only useful	1086	Simply stops and restarts the periodic watcher again. This is only useful
958	when you changed some parameters or the reschedule callback would return	1087	when you changed some parameters or the reschedule callback would return
959	a different time than the last time it was called (e.g. in a crond like	1088	a different time than the last time it was called (e.g. in a crond like
960	program when the crontabs have changed).	1089	program when the crontabs have changed).
961		1090
		1091	=item ev_tstamp interval [read-write]
		1092
		1093	The current interval value. Can be modified any time, but changes only
		1094	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1095	called.
		1096
		1097	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
		1098
		1099	The current reschedule callback, or C<0>, if this functionality is
		1100	switched off. Can be changed any time, but changes only take effect when
		1101	the periodic timer fires or C<ev_periodic_again> is being called.
		1102
962	=back	1103	=back
963		1104
964	Example: call a callback every hour, or, more precisely, whenever the	1105	Example: Call a callback every hour, or, more precisely, whenever the
965	system clock is divisible by 3600. The callback invocation times have	1106	system clock is divisible by 3600. The callback invocation times have
966	potentially a lot of jittering, but good long-term stability.	1107	potentially a lot of jittering, but good long-term stability.
967		1108
968	static void	1109	static void
969	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1110	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
973		1114
974	struct ev_periodic hourly_tick;	1115	struct ev_periodic hourly_tick;
975	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1116	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
976	ev_periodic_start (loop, &hourly_tick);	1117	ev_periodic_start (loop, &hourly_tick);
977		1118
978	Example: the same as above, but use a reschedule callback to do it:	1119	Example: The same as above, but use a reschedule callback to do it:
979		1120
980	#include <math.h>	1121	#include <math.h>
981		1122
982	static ev_tstamp	1123	static ev_tstamp
983	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1124	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
985	return fmod (now, 3600.) + 3600.;	1126	return fmod (now, 3600.) + 3600.;
986	}	1127	}
987		1128
988	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1129	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
989		1130
990	Example: call a callback every hour, starting now:	1131	Example: Call a callback every hour, starting now:
991		1132
992	struct ev_periodic hourly_tick;	1133	struct ev_periodic hourly_tick;
993	ev_periodic_init (&hourly_tick, clock_cb,	1134	ev_periodic_init (&hourly_tick, clock_cb,
994	fmod (ev_now (loop), 3600.), 3600., 0);	1135	fmod (ev_now (loop), 3600.), 3600., 0);
995	ev_periodic_start (loop, &hourly_tick);	1136	ev_periodic_start (loop, &hourly_tick);
…		…
1016	=item ev_signal_set (ev_signal *, int signum)	1157	=item ev_signal_set (ev_signal *, int signum)
1017		1158
1018	Configures the watcher to trigger on the given signal number (usually one	1159	Configures the watcher to trigger on the given signal number (usually one
1019	of the C<SIGxxx> constants).	1160	of the C<SIGxxx> constants).
1020		1161
		1162	=item int signum [read-only]
		1163
		1164	The signal the watcher watches out for.
		1165
1021	=back	1166	=back
1022		1167
1023		1168
1024	=head2 C<ev_child> - watch out for process status changes	1169	=head2 C<ev_child> - watch out for process status changes
1025		1170
…		…
1037	at the C<rstatus> member of the C<ev_child> watcher structure to see	1182	at the C<rstatus> member of the C<ev_child> watcher structure to see
1038	the status word (use the macros from C<sys/wait.h> and see your systems	1183	the status word (use the macros from C<sys/wait.h> and see your systems
1039	C<waitpid> documentation). The C<rpid> member contains the pid of the	1184	C<waitpid> documentation). The C<rpid> member contains the pid of the
1040	process causing the status change.	1185	process causing the status change.
1041		1186
		1187	=item int pid [read-only]
		1188
		1189	The process id this watcher watches out for, or C<0>, meaning any process id.
		1190
		1191	=item int rpid [read-write]
		1192
		1193	The process id that detected a status change.
		1194
		1195	=item int rstatus [read-write]
		1196
		1197	The process exit/trace status caused by C<rpid> (see your systems
		1198	C<waitpid> and C<sys/wait.h> documentation for details).
		1199
1042	=back	1200	=back
1043		1201
1044	Example: try to exit cleanly on SIGINT and SIGTERM.	1202	Example: Try to exit cleanly on SIGINT and SIGTERM.
1045		1203
1046	static void	1204	static void
1047	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1205	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1048	{	1206	{
1049	ev_unloop (loop, EVUNLOOP_ALL);	1207	ev_unloop (loop, EVUNLOOP_ALL);
1050	}	1208	}
1051		1209
1052	struct ev_signal signal_watcher;	1210	struct ev_signal signal_watcher;
1053	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1211	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1054	ev_signal_start (loop, &sigint_cb);	1212	ev_signal_start (loop, &sigint_cb);
		1213
		1214
		1215	=head2 C<ev_stat> - did the file attributes just change?
		1216
		1217	This watches a filesystem path for attribute changes. That is, it calls
		1218	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1219	compared to the last time, invoking the callback if it did.
		1220
		1221	The path does not need to exist: changing from "path exists" to "path does
		1222	not exist" is a status change like any other. The condition "path does
		1223	not exist" is signified by the C<st_nlink> field being zero (which is
		1224	otherwise always forced to be at least one) and all the other fields of
		1225	the stat buffer having unspecified contents.
		1226
		1227	Since there is no standard to do this, the portable implementation simply
		1228	calls C<stat (2)> regularly on the path to see if it changed somehow. You
		1229	can specify a recommended polling interval for this case. If you specify
		1230	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1231	unspecified default> value will be used (which you can expect to be around
		1232	five seconds, although this might change dynamically). Libev will also
		1233	impose a minimum interval which is currently around C<0.1>, but thats
		1234	usually overkill.
		1235
		1236	This watcher type is not meant for massive numbers of stat watchers,
		1237	as even with OS-supported change notifications, this can be
		1238	resource-intensive.
		1239
		1240	At the time of this writing, only the Linux inotify interface is
		1241	implemented (implementing kqueue support is left as an exercise for the
		1242	reader). Inotify will be used to give hints only and should not change the
		1243	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1244	to fall back to regular polling again even with inotify, but changes are
		1245	usually detected immediately, and if the file exists there will be no
		1246	polling.
		1247
		1248	=over 4
		1249
		1250	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
		1251
		1252	=item ev_stat_set (ev_stat , const char path, ev_tstamp interval)
		1253
		1254	Configures the watcher to wait for status changes of the given
		1255	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1256	be detected and should normally be specified as C<0> to let libev choose
		1257	a suitable value. The memory pointed to by C<path> must point to the same
		1258	path for as long as the watcher is active.
		1259
		1260	The callback will be receive C<EV_STAT> when a change was detected,
		1261	relative to the attributes at the time the watcher was started (or the
		1262	last change was detected).
		1263
		1264	=item ev_stat_stat (ev_stat *)
		1265
		1266	Updates the stat buffer immediately with new values. If you change the
		1267	watched path in your callback, you could call this fucntion to avoid
		1268	detecting this change (while introducing a race condition). Can also be
		1269	useful simply to find out the new values.
		1270
		1271	=item ev_statdata attr [read-only]
		1272
		1273	The most-recently detected attributes of the file. Although the type is of
		1274	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1275	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1276	was some error while C<stat>ing the file.
		1277
		1278	=item ev_statdata prev [read-only]
		1279
		1280	The previous attributes of the file. The callback gets invoked whenever
		1281	C<prev> != C<attr>.
		1282
		1283	=item ev_tstamp interval [read-only]
		1284
		1285	The specified interval.
		1286
		1287	=item const char *path [read-only]
		1288
		1289	The filesystem path that is being watched.
		1290
		1291	=back
		1292
		1293	Example: Watch C</etc/passwd> for attribute changes.
		1294
		1295	static void
		1296	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1297	{
		1298	/* /etc/passwd changed in some way */
		1299	if (w->attr.st_nlink)
		1300	{
		1301	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1302	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1303	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1304	}
		1305	else
		1306	/* you shalt not abuse printf for puts */
		1307	puts ("wow, /etc/passwd is not there, expect problems. "
		1308	"if this is windows, they already arrived\n");
		1309	}
		1310
		1311	...
		1312	ev_stat passwd;
		1313
		1314	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1315	ev_stat_start (loop, &passwd);
1055		1316
1056		1317
1057	=head2 C<ev_idle> - when you've got nothing better to do...	1318	=head2 C<ev_idle> - when you've got nothing better to do...
1058		1319
1059	Idle watchers trigger events when there are no other events are pending	1320	Idle watchers trigger events when there are no other events are pending
…		…
1080	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1341	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1081	believe me.	1342	believe me.
1082		1343
1083	=back	1344	=back
1084		1345
1085	Example: dynamically allocate an C<ev_idle>, start it, and in the	1346	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1086	callback, free it. Alos, use no error checking, as usual.	1347	callback, free it. Also, use no error checking, as usual.
1087		1348
1088	static void	1349	static void
1089	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1350	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1090	{	1351	{
1091	free (w);	1352	free (w);
…		…
1292		1553
1293	Make a single, non-blocking sweep over the embedded loop. This works	1554	Make a single, non-blocking sweep over the embedded loop. This works
1294	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1555	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1295	apropriate way for embedded loops.	1556	apropriate way for embedded loops.
1296		1557
		1558	=item struct ev_loop *loop [read-only]
		1559
		1560	The embedded event loop.
		1561
		1562	=back
		1563
		1564
		1565	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1566
		1567	Fork watchers are called when a C<fork ()> was detected (usually because
		1568	whoever is a good citizen cared to tell libev about it by calling
		1569	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1570	event loop blocks next and before C<ev_check> watchers are being called,
		1571	and only in the child after the fork. If whoever good citizen calling
		1572	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1573	handlers will be invoked, too, of course.
		1574
		1575	=over 4
		1576
		1577	=item ev_fork_init (ev_signal *, callback)
		1578
		1579	Initialises and configures the fork watcher - it has no parameters of any
		1580	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1581	believe me.
		1582
1297	=back	1583	=back
1298		1584
1299		1585
1300	=head1 OTHER FUNCTIONS	1586	=head1 OTHER FUNCTIONS
1301		1587
…		…
1463		1749
1464	=item w->sweep () C<ev::embed> only	1750	=item w->sweep () C<ev::embed> only
1465		1751
1466	Invokes C<ev_embed_sweep>.	1752	Invokes C<ev_embed_sweep>.
1467		1753
		1754	=item w->update () C<ev::stat> only
		1755
		1756	Invokes C<ev_stat_stat>.
		1757
1468	=back	1758	=back
1469		1759
1470	=back	1760	=back
1471		1761
1472	Example: Define a class with an IO and idle watcher, start one of them in	1762	Example: Define a class with an IO and idle watcher, start one of them in
…		…
1484	: io (this, &myclass::io_cb),	1774	: io (this, &myclass::io_cb),
1485	idle (this, &myclass::idle_cb)	1775	idle (this, &myclass::idle_cb)
1486	{	1776	{
1487	io.start (fd, ev::READ);	1777	io.start (fd, ev::READ);
1488	}	1778	}
		1779
		1780
		1781	=head1 MACRO MAGIC
		1782
		1783	Libev can be compiled with a variety of options, the most fundemantal is
		1784	C<EV_MULTIPLICITY>. This option determines wether (most) functions and
		1785	callbacks have an initial C<struct ev_loop *> argument.
		1786
		1787	To make it easier to write programs that cope with either variant, the
		1788	following macros are defined:
		1789
		1790	=over 4
		1791
		1792	=item C<EV_A>, C<EV_A_>
		1793
		1794	This provides the loop I<argument> for functions, if one is required ("ev
		1795	loop argument"). The C<EV_A> form is used when this is the sole argument,
		1796	C<EV_A_> is used when other arguments are following. Example:
		1797
		1798	ev_unref (EV_A);
		1799	ev_timer_add (EV_A_ watcher);
		1800	ev_loop (EV_A_ 0);
		1801
		1802	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		1803	which is often provided by the following macro.
		1804
		1805	=item C<EV_P>, C<EV_P_>
		1806
		1807	This provides the loop I<parameter> for functions, if one is required ("ev
		1808	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		1809	C<EV_P_> is used when other parameters are following. Example:
		1810
		1811	// this is how ev_unref is being declared
		1812	static void ev_unref (EV_P);
		1813
		1814	// this is how you can declare your typical callback
		1815	static void cb (EV_P_ ev_timer *w, int revents)
		1816
		1817	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		1818	suitable for use with C<EV_A>.
		1819
		1820	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		1821
		1822	Similar to the other two macros, this gives you the value of the default
		1823	loop, if multiple loops are supported ("ev loop default").
		1824
		1825	=back
		1826
		1827	Example: Declare and initialise a check watcher, working regardless of
		1828	wether multiple loops are supported or not.
		1829
		1830	static void
		1831	check_cb (EV_P_ ev_timer *w, int revents)
		1832	{
		1833	ev_check_stop (EV_A_ w);
		1834	}
		1835
		1836	ev_check check;
		1837	ev_check_init (&check, check_cb);
		1838	ev_check_start (EV_DEFAULT_ &check);
		1839	ev_loop (EV_DEFAULT_ 0);
		1840
1489		1841
1490	=head1 EMBEDDING	1842	=head1 EMBEDDING
1491		1843
1492	Libev can (and often is) directly embedded into host	1844	Libev can (and often is) directly embedded into host
1493	applications. Examples of applications that embed it include the Deliantra	1845	applications. Examples of applications that embed it include the Deliantra
…		…
1668		2020
1669	=item EV_USE_DEVPOLL	2021	=item EV_USE_DEVPOLL
1670		2022
1671	reserved for future expansion, works like the USE symbols above.	2023	reserved for future expansion, works like the USE symbols above.
1672		2024
		2025	=item EV_USE_INOTIFY
		2026
		2027	If defined to be C<1>, libev will compile in support for the Linux inotify
		2028	interface to speed up C<ev_stat> watchers. Its actual availability will
		2029	be detected at runtime.
		2030
1673	=item EV_H	2031	=item EV_H
1674		2032
1675	The name of the F<ev.h> header file used to include it. The default if	2033	The name of the F<ev.h> header file used to include it. The default if
1676	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2034	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
1677	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2035	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
1700	will have the C<struct ev_loop *> as first argument, and you can create	2058	will have the C<struct ev_loop *> as first argument, and you can create
1701	additional independent event loops. Otherwise there will be no support	2059	additional independent event loops. Otherwise there will be no support
1702	for multiple event loops and there is no first event loop pointer	2060	for multiple event loops and there is no first event loop pointer
1703	argument. Instead, all functions act on the single default loop.	2061	argument. Instead, all functions act on the single default loop.
1704		2062
1705	=item EV_PERIODICS	2063	=item EV_PERIODIC_ENABLE
1706		2064
1707	If undefined or defined to be C<1>, then periodic timers are supported,	2065	If undefined or defined to be C<1>, then periodic timers are supported. If
1708	otherwise not. This saves a few kb of code.	2066	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2067	code.
		2068
		2069	=item EV_EMBED_ENABLE
		2070
		2071	If undefined or defined to be C<1>, then embed watchers are supported. If
		2072	defined to be C<0>, then they are not.
		2073
		2074	=item EV_STAT_ENABLE
		2075
		2076	If undefined or defined to be C<1>, then stat watchers are supported. If
		2077	defined to be C<0>, then they are not.
		2078
		2079	=item EV_FORK_ENABLE
		2080
		2081	If undefined or defined to be C<1>, then fork watchers are supported. If
		2082	defined to be C<0>, then they are not.
		2083
		2084	=item EV_MINIMAL
		2085
		2086	If you need to shave off some kilobytes of code at the expense of some
		2087	speed, define this symbol to C<1>. Currently only used for gcc to override
		2088	some inlining decisions, saves roughly 30% codesize of amd64.
		2089
		2090	=item EV_PID_HASHSIZE
		2091
		2092	C<ev_child> watchers use a small hash table to distribute workload by
		2093	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2094	than enough. If you need to manage thousands of children you might want to
		2095	increase this value (I<must> be a power of two).
		2096
		2097	=item EV_INOTIFY_HASHSIZE
		2098
		2099	C<ev_staz> watchers use a small hash table to distribute workload by
		2100	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2101	usually more than enough. If you need to manage thousands of C<ev_stat>
		2102	watchers you might want to increase this value (I<must> be a power of
		2103	two).
1709		2104
1710	=item EV_COMMON	2105	=item EV_COMMON
1711		2106
1712	By default, all watchers have a C<void *data> member. By redefining	2107	By default, all watchers have a C<void *data> member. By redefining
1713	this macro to a something else you can include more and other types of	2108	this macro to a something else you can include more and other types of
…		…
1773		2168
1774	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2169	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
1775		2170
1776	=item Stopping check/prepare/idle watchers: O(1)	2171	=item Stopping check/prepare/idle watchers: O(1)
1777		2172
1778	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2173	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
1779		2174
1780	=item Finding the next timer per loop iteration: O(1)	2175	=item Finding the next timer per loop iteration: O(1)
1781		2176
1782	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2177	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
1783		2178

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Comparing libev/ev.pod (file contents): Revision 1.46 by root, Mon Nov 26 10:20:43 2007 UTC vs. Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.46 by root, Mon Nov 26 10:20:43 2007 UTC vs.
Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC