[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 1.54 by root, Tue Nov 27 20:26:51 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>), relative timers (C<ev_timer>),
29	events (related to SIGCHLD), and event watchers dealing with the event	71	absolute timers with customised rescheduling (C<ev_periodic>), synchronous
30	loop mechanism itself (idle, prepare and check watchers). It also is quite	72	signals (C<ev_signal>), process status change events (C<ev_child>), and
		73	event watchers dealing with the event loop mechanism itself (C<ev_idle>,
		74	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
		75	file watchers (C<ev_stat>) and even limited support for fork events
		76	(C<ev_fork>).
		77
		78	It also is quite fast (see this
31	fast (see this L<benchmark\|http://libev.schmorp.de/bench.html> comparing	79	L<benchmark\|http://libev.schmorp.de/bench.html> comparing it to libevent
32	it to libevent for example).	80	for example).
33		81
34	=head1 CONVENTIONS	82	=head1 CONVENTIONS
35		83
36	Libev is very configurable. In this manual the default configuration	84	Libev is very configurable. In this manual the default configuration will
37	will be described, which supports multiple event loops. For more info	85	be described, which supports multiple event loops. For more info about
38	about various configuration options please have a look at the file	86	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	87	this manual. If libev was configured without support for multiple event
40	support for multiple event loops, then all functions taking an initial	88	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 *>)	89	(which is always of type C<struct ev_loop *>) will not have this argument.
42	will not have this argument.
43		90
44	=head1 TIME REPRESENTATION	91	=head1 TIME REPRESENTATION
45		92
46	Libev represents time as a single floating point number, representing the	93	Libev represents time as a single floating point number, representing the
47	(fractional) number of seconds since the (POSIX) epoch (somewhere near	94	(fractional) number of seconds since the (POSIX) epoch (somewhere near
48	the beginning of 1970, details are complicated, don't ask). This type is	95	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	96	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	97	to the C<double> type in C, and when you need to do any calculations on
51	it, you should treat it as such.	98	it, you should treat it as such.
52		99
53
54	=head1 GLOBAL FUNCTIONS	100	=head1 GLOBAL FUNCTIONS
55		101
56	These functions can be called anytime, even before initialising the	102	These functions can be called anytime, even before initialising the
57	library in any way.	103	library in any way.
58		104
…		…
77	Usually, it's a good idea to terminate if the major versions mismatch,	123	Usually, it's a good idea to terminate if the major versions mismatch,
78	as this indicates an incompatible change. Minor versions are usually	124	as this indicates an incompatible change. Minor versions are usually
79	compatible to older versions, so a larger minor version alone is usually	125	compatible to older versions, so a larger minor version alone is usually
80	not a problem.	126	not a problem.
81		127
82	Example: make sure we haven't accidentally been linked against the wrong	128	Example: Make sure we haven't accidentally been linked against the wrong
83	version:	129	version.
84		130
85	assert (("libev version mismatch",	131	assert (("libev version mismatch",
86	ev_version_major () == EV_VERSION_MAJOR	132	ev_version_major () == EV_VERSION_MAJOR
87	&& ev_version_minor () >= EV_VERSION_MINOR));	133	&& ev_version_minor () >= EV_VERSION_MINOR));
88		134
…		…
116	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	162	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
117	recommended ones.	163	recommended ones.
118		164
119	See the description of C<ev_embed> watchers for more info.	165	See the description of C<ev_embed> watchers for more info.
120		166
121	=item ev_set_allocator (void (cb)(void *ptr, long size))	167	=item ev_set_allocator (void (cb)(void *ptr, size_t size))
122		168
123	Sets the allocation function to use (the prototype is similar to the	169	Sets the allocation function to use (the prototype and semantics are
124	realloc C function, the semantics are identical). It is used to allocate	170	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	171	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	172	allocated, the library might abort or take some potentially destructive
127	destructive action. The default is your system realloc function.	173	action. The default is your system realloc function.
128		174
129	You could override this function in high-availability programs to, say,	175	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,	176	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.	177	or even to sleep a while and retry until some memory is available.
132		178
133	Example: replace the libev allocator with one that waits a bit and then	179	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	180	retries).
135		181
136	static void *	182	static void *
137	persistent_realloc (void *ptr, long size)	183	persistent_realloc (void *ptr, size_t size)
138	{	184	{
139	for (;;)	185	for (;;)
140	{	186	{
141	void *newptr = realloc (ptr, size);	187	void *newptr = realloc (ptr, size);
142		188
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	204	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	205	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	206	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	207	(such as abort).
162		208
163	Example: do the same thing as libev does internally:	209	Example: This is basically the same thing that libev does internally, too.
164		210
165	static void	211	static void
166	fatal_error (const char *msg)	212	fatal_error (const char *msg)
167	{	213	{
168	perror (msg);	214	perror (msg);
…		…
314	Similar to C<ev_default_loop>, but always creates a new event loop that is	360	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	361	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	362	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).	363	undefined behaviour (or a failed assertion if assertions are enabled).
318		364
319	Example: try to create a event loop that uses epoll and nothing else.	365	Example: Try to create a event loop that uses epoll and nothing else.
320		366
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	367	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
322	if (!epoller)	368	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	369	fatal ("no epoll found here, maybe it hides under your chair");
324		370
…		…
423	Signals and child watchers are implemented as I/O watchers, and will	469	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	470	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	471	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	472	were used, return, otherwise continue with step *.
427		473
428	Example: queue some jobs and then loop until no events are outsanding	474	Example: Queue some jobs and then loop until no events are outsanding
429	anymore.	475	anymore.
430		476
431	... queue jobs here, make sure they register event watchers as long	477	... 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..)	478	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	479	ev_loop (my_loop, 0);
…		…
453	visible to the libev user and should not keep C<ev_loop> from exiting if	499	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	500	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	501	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>.	502	libraries. Just remember to I<unref after start> and I<ref before stop>.
457		503
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	504	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	505	running when nothing else is active.
460		506
461	struct dv_signal exitsig;	507	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	508	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	509	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	510	evf_unref (loop);
465		511
466	Example: for some weird reason, unregister the above signal handler again.	512	Example: For some weird reason, unregister the above signal handler again.
467		513
468	ev_ref (myloop);	514	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	515	ev_signal_stop (loop, &exitsig);
470		516
471	=back	517	=back
472		518
473		519
474	=head1 ANATOMY OF A WATCHER	520	=head1 ANATOMY OF A WATCHER
…		…
544	The signal specified in the C<ev_signal> watcher has been received by a thread.	590	The signal specified in the C<ev_signal> watcher has been received by a thread.
545		591
546	=item C<EV_CHILD>	592	=item C<EV_CHILD>
547		593
548	The pid specified in the C<ev_child> watcher has received a status change.	594	The pid specified in the C<ev_child> watcher has received a status change.
		595
		596	=item C<EV_STAT>
		597
		598	The path specified in the C<ev_stat> watcher changed its attributes somehow.
549		599
550	=item C<EV_IDLE>	600	=item C<EV_IDLE>
551		601
552	The C<ev_idle> watcher has determined that you have nothing better to do.	602	The C<ev_idle> watcher has determined that you have nothing better to do.
553		603
…		…
561	received events. Callbacks of both watcher types can start and stop as	611	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	612	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	613	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
564	C<ev_loop> from blocking).	614	C<ev_loop> from blocking).
565		615
		616	=item C<EV_EMBED>
		617
		618	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		619
		620	=item C<EV_FORK>
		621
		622	The event loop has been resumed in the child process after fork (see
		623	C<ev_fork>).
		624
566	=item C<EV_ERROR>	625	=item C<EV_ERROR>
567		626
568	An unspecified error has occured, the watcher has been stopped. This might	627	An unspecified error has occured, the watcher has been stopped. This might
569	happen because the watcher could not be properly started because libev	628	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	629	ran out of memory, a file descriptor was found to be closed or any other
…		…
689		748
690		749
691	=head1 WATCHER TYPES	750	=head1 WATCHER TYPES
692		751
693	This section describes each watcher in detail, but will not repeat	752	This section describes each watcher in detail, but will not repeat
694	information given in the last section.	753	information given in the last section. Any initialisation/set macros,
		754	functions and members specific to the watcher type are explained.
		755
		756	Members are additionally marked with either I<[read-only]>, meaning that,
		757	while the watcher is active, you can look at the member and expect some
		758	sensible content, but you must not modify it (you can modify it while the
		759	watcher is stopped to your hearts content), or I<[read-write]>, which
		760	means you can expect it to have some sensible content while the watcher
		761	is active, but you can also modify it. Modifying it may not do something
		762	sensible or take immediate effect (or do anything at all), but libev will
		763	not crash or malfunction in any way.
695		764
696		765
697	=head2 C<ev_io> - is this file descriptor readable or writable?	766	=head2 C<ev_io> - is this file descriptor readable or writable?
698		767
699	I/O watchers check whether a file descriptor is readable or writable	768	I/O watchers check whether a file descriptor is readable or writable
…		…
742		811
743	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	812	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	813	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.	814	C<EV_READ \| EV_WRITE> to receive the given events.
746		815
		816	=item int fd [read-only]
		817
		818	The file descriptor being watched.
		819
		820	=item int events [read-only]
		821
		822	The events being watched.
		823
747	=back	824	=back
748		825
749	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	826	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	827	readable, but only once. Since it is likely line-buffered, you could
751	attempt to read a whole line in the callback:	828	attempt to read a whole line in the callback.
752		829
753	static void	830	static void
754	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	831	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
755	{	832	{
756	ev_io_stop (loop, w);	833	ev_io_stop (loop, w);
…		…
814		891
815	If the timer is repeating, either start it if necessary (with the repeat	892	If the timer is repeating, either start it if necessary (with the repeat
816	value), or reset the running timer to the repeat value.	893	value), or reset the running timer to the repeat value.
817		894
818	This sounds a bit complicated, but here is a useful and typical	895	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	896	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	897	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	898	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	899	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	900	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	901	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.	902	socket, you can stop the timer, and again will automatically restart it if
		903	need be.
		904
		905	You can also ignore the C<after> value and C<ev_timer_start> altogether
		906	and only ever use the C<repeat> value:
		907
		908	ev_timer_init (timer, callback, 0., 5.);
		909	ev_timer_again (loop, timer);
		910	...
		911	timer->again = 17.;
		912	ev_timer_again (loop, timer);
		913	...
		914	timer->again = 10.;
		915	ev_timer_again (loop, timer);
		916
		917	This is more efficient then stopping/starting the timer eahc time you want
		918	to modify its timeout value.
		919
		920	=item ev_tstamp repeat [read-write]
		921
		922	The current C<repeat> value. Will be used each time the watcher times out
		923	or C<ev_timer_again> is called and determines the next timeout (if any),
		924	which is also when any modifications are taken into account.
826		925
827	=back	926	=back
828		927
829	Example: create a timer that fires after 60 seconds.	928	Example: Create a timer that fires after 60 seconds.
830		929
831	static void	930	static void
832	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	931	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
833	{	932	{
834	.. one minute over, w is actually stopped right here	933	.. one minute over, w is actually stopped right here
…		…
836		935
837	struct ev_timer mytimer;	936	struct ev_timer mytimer;
838	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	937	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
839	ev_timer_start (loop, &mytimer);	938	ev_timer_start (loop, &mytimer);
840		939
841	Example: create a timeout timer that times out after 10 seconds of	940	Example: Create a timeout timer that times out after 10 seconds of
842	inactivity.	941	inactivity.
843		942
844	static void	943	static void
845	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	944	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
846	{	945	{
…		…
957	Simply stops and restarts the periodic watcher again. This is only useful	1056	Simply stops and restarts the periodic watcher again. This is only useful
958	when you changed some parameters or the reschedule callback would return	1057	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	1058	a different time than the last time it was called (e.g. in a crond like
960	program when the crontabs have changed).	1059	program when the crontabs have changed).
961		1060
		1061	=item ev_tstamp interval [read-write]
		1062
		1063	The current interval value. Can be modified any time, but changes only
		1064	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1065	called.
		1066
		1067	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
		1068
		1069	The current reschedule callback, or C<0>, if this functionality is
		1070	switched off. Can be changed any time, but changes only take effect when
		1071	the periodic timer fires or C<ev_periodic_again> is being called.
		1072
962	=back	1073	=back
963		1074
964	Example: call a callback every hour, or, more precisely, whenever the	1075	Example: Call a callback every hour, or, more precisely, whenever the
965	system clock is divisible by 3600. The callback invocation times have	1076	system clock is divisible by 3600. The callback invocation times have
966	potentially a lot of jittering, but good long-term stability.	1077	potentially a lot of jittering, but good long-term stability.
967		1078
968	static void	1079	static void
969	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1080	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
973		1084
974	struct ev_periodic hourly_tick;	1085	struct ev_periodic hourly_tick;
975	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1086	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
976	ev_periodic_start (loop, &hourly_tick);	1087	ev_periodic_start (loop, &hourly_tick);
977		1088
978	Example: the same as above, but use a reschedule callback to do it:	1089	Example: The same as above, but use a reschedule callback to do it:
979		1090
980	#include <math.h>	1091	#include <math.h>
981		1092
982	static ev_tstamp	1093	static ev_tstamp
983	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1094	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
985	return fmod (now, 3600.) + 3600.;	1096	return fmod (now, 3600.) + 3600.;
986	}	1097	}
987		1098
988	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1099	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
989		1100
990	Example: call a callback every hour, starting now:	1101	Example: Call a callback every hour, starting now:
991		1102
992	struct ev_periodic hourly_tick;	1103	struct ev_periodic hourly_tick;
993	ev_periodic_init (&hourly_tick, clock_cb,	1104	ev_periodic_init (&hourly_tick, clock_cb,
994	fmod (ev_now (loop), 3600.), 3600., 0);	1105	fmod (ev_now (loop), 3600.), 3600., 0);
995	ev_periodic_start (loop, &hourly_tick);	1106	ev_periodic_start (loop, &hourly_tick);
…		…
1016	=item ev_signal_set (ev_signal *, int signum)	1127	=item ev_signal_set (ev_signal *, int signum)
1017		1128
1018	Configures the watcher to trigger on the given signal number (usually one	1129	Configures the watcher to trigger on the given signal number (usually one
1019	of the C<SIGxxx> constants).	1130	of the C<SIGxxx> constants).
1020		1131
		1132	=item int signum [read-only]
		1133
		1134	The signal the watcher watches out for.
		1135
1021	=back	1136	=back
1022		1137
1023		1138
1024	=head2 C<ev_child> - watch out for process status changes	1139	=head2 C<ev_child> - watch out for process status changes
1025		1140
…		…
1037	at the C<rstatus> member of the C<ev_child> watcher structure to see	1152	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	1153	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	1154	C<waitpid> documentation). The C<rpid> member contains the pid of the
1040	process causing the status change.	1155	process causing the status change.
1041		1156
		1157	=item int pid [read-only]
		1158
		1159	The process id this watcher watches out for, or C<0>, meaning any process id.
		1160
		1161	=item int rpid [read-write]
		1162
		1163	The process id that detected a status change.
		1164
		1165	=item int rstatus [read-write]
		1166
		1167	The process exit/trace status caused by C<rpid> (see your systems
		1168	C<waitpid> and C<sys/wait.h> documentation for details).
		1169
1042	=back	1170	=back
1043		1171
1044	Example: try to exit cleanly on SIGINT and SIGTERM.	1172	Example: Try to exit cleanly on SIGINT and SIGTERM.
1045		1173
1046	static void	1174	static void
1047	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1175	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1048	{	1176	{
1049	ev_unloop (loop, EVUNLOOP_ALL);	1177	ev_unloop (loop, EVUNLOOP_ALL);
1050	}	1178	}
1051		1179
1052	struct ev_signal signal_watcher;	1180	struct ev_signal signal_watcher;
1053	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1181	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1054	ev_signal_start (loop, &sigint_cb);	1182	ev_signal_start (loop, &sigint_cb);
		1183
		1184
		1185	=head2 C<ev_stat> - did the file attributes just change?
		1186
		1187	This watches a filesystem path for attribute changes. That is, it calls
		1188	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1189	compared to the last time, invoking the callback if it did.
		1190
		1191	The path does not need to exist: changing from "path exists" to "path does
		1192	not exist" is a status change like any other. The condition "path does
		1193	not exist" is signified by the C<st_nlink> field being zero (which is
		1194	otherwise always forced to be at least one) and all the other fields of
		1195	the stat buffer having unspecified contents.
		1196
		1197	Since there is no standard to do this, the portable implementation simply
		1198	calls C<stat (2)> regulalry on the path to see if it changed somehow. You
		1199	can specify a recommended polling interval for this case. If you specify
		1200	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1201	unspecified default> value will be used (which you can expect to be around
		1202	five seconds, although this might change dynamically). Libev will also
		1203	impose a minimum interval which is currently around C<0.1>, but thats
		1204	usually overkill.
		1205
		1206	This watcher type is not meant for massive numbers of stat watchers,
		1207	as even with OS-supported change notifications, this can be
		1208	resource-intensive.
		1209
		1210	At the time of this writing, no specific OS backends are implemented, but
		1211	if demand increases, at least a kqueue and inotify backend will be added.
		1212
		1213	=over 4
		1214
		1215	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
		1216
		1217	=item ev_stat_set (ev_stat , const char path, ev_tstamp interval)
		1218
		1219	Configures the watcher to wait for status changes of the given
		1220	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1221	be detected and should normally be specified as C<0> to let libev choose
		1222	a suitable value. The memory pointed to by C<path> must point to the same
		1223	path for as long as the watcher is active.
		1224
		1225	The callback will be receive C<EV_STAT> when a change was detected,
		1226	relative to the attributes at the time the watcher was started (or the
		1227	last change was detected).
		1228
		1229	=item ev_stat_stat (ev_stat *)
		1230
		1231	Updates the stat buffer immediately with new values. If you change the
		1232	watched path in your callback, you could call this fucntion to avoid
		1233	detecting this change (while introducing a race condition). Can also be
		1234	useful simply to find out the new values.
		1235
		1236	=item ev_statdata attr [read-only]
		1237
		1238	The most-recently detected attributes of the file. Although the type is of
		1239	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1240	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1241	was some error while C<stat>ing the file.
		1242
		1243	=item ev_statdata prev [read-only]
		1244
		1245	The previous attributes of the file. The callback gets invoked whenever
		1246	C<prev> != C<attr>.
		1247
		1248	=item ev_tstamp interval [read-only]
		1249
		1250	The specified interval.
		1251
		1252	=item const char *path [read-only]
		1253
		1254	The filesystem path that is being watched.
		1255
		1256	=back
		1257
		1258	Example: Watch C</etc/passwd> for attribute changes.
		1259
		1260	static void
		1261	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1262	{
		1263	/* /etc/passwd changed in some way */
		1264	if (w->attr.st_nlink)
		1265	{
		1266	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1267	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1268	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1269	}
		1270	else
		1271	/* you shalt not abuse printf for puts */
		1272	puts ("wow, /etc/passwd is not there, expect problems. "
		1273	"if this is windows, they already arrived\n");
		1274	}
		1275
		1276	...
		1277	ev_stat passwd;
		1278
		1279	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1280	ev_stat_start (loop, &passwd);
1055		1281
1056		1282
1057	=head2 C<ev_idle> - when you've got nothing better to do...	1283	=head2 C<ev_idle> - when you've got nothing better to do...
1058		1284
1059	Idle watchers trigger events when there are no other events are pending	1285	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,	1306	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1081	believe me.	1307	believe me.
1082		1308
1083	=back	1309	=back
1084		1310
1085	Example: dynamically allocate an C<ev_idle>, start it, and in the	1311	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1086	callback, free it. Alos, use no error checking, as usual.	1312	callback, free it. Also, use no error checking, as usual.
1087		1313
1088	static void	1314	static void
1089	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1315	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1090	{	1316	{
1091	free (w);	1317	free (w);
…		…
1292		1518
1293	Make a single, non-blocking sweep over the embedded loop. This works	1519	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	1520	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1295	apropriate way for embedded loops.	1521	apropriate way for embedded loops.
1296		1522
		1523	=item struct ev_loop *loop [read-only]
		1524
		1525	The embedded event loop.
		1526
		1527	=back
		1528
		1529
		1530	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1531
		1532	Fork watchers are called when a C<fork ()> was detected (usually because
		1533	whoever is a good citizen cared to tell libev about it by calling
		1534	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1535	event loop blocks next and before C<ev_check> watchers are being called,
		1536	and only in the child after the fork. If whoever good citizen calling
		1537	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1538	handlers will be invoked, too, of course.
		1539
		1540	=over 4
		1541
		1542	=item ev_fork_init (ev_signal *, callback)
		1543
		1544	Initialises and configures the fork watcher - it has no parameters of any
		1545	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1546	believe me.
		1547
1297	=back	1548	=back
1298		1549
1299		1550
1300	=head1 OTHER FUNCTIONS	1551	=head1 OTHER FUNCTIONS
1301		1552
…		…
1463		1714
1464	=item w->sweep () C<ev::embed> only	1715	=item w->sweep () C<ev::embed> only
1465		1716
1466	Invokes C<ev_embed_sweep>.	1717	Invokes C<ev_embed_sweep>.
1467		1718
		1719	=item w->update () C<ev::stat> only
		1720
		1721	Invokes C<ev_stat_stat>.
		1722
1468	=back	1723	=back
1469		1724
1470	=back	1725	=back
1471		1726
1472	Example: Define a class with an IO and idle watcher, start one of them in	1727	Example: Define a class with an IO and idle watcher, start one of them in
…		…
1484	: io (this, &myclass::io_cb),	1739	: io (this, &myclass::io_cb),
1485	idle (this, &myclass::idle_cb)	1740	idle (this, &myclass::idle_cb)
1486	{	1741	{
1487	io.start (fd, ev::READ);	1742	io.start (fd, ev::READ);
1488	}	1743	}
		1744
		1745
		1746	=head1 MACRO MAGIC
		1747
		1748	Libev can be compiled with a variety of options, the most fundemantal is
		1749	C<EV_MULTIPLICITY>. This option determines wether (most) functions and
		1750	callbacks have an initial C<struct ev_loop *> argument.
		1751
		1752	To make it easier to write programs that cope with either variant, the
		1753	following macros are defined:
		1754
		1755	=over 4
		1756
		1757	=item C<EV_A>, C<EV_A_>
		1758
		1759	This provides the loop I<argument> for functions, if one is required ("ev
		1760	loop argument"). The C<EV_A> form is used when this is the sole argument,
		1761	C<EV_A_> is used when other arguments are following. Example:
		1762
		1763	ev_unref (EV_A);
		1764	ev_timer_add (EV_A_ watcher);
		1765	ev_loop (EV_A_ 0);
		1766
		1767	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		1768	which is often provided by the following macro.
		1769
		1770	=item C<EV_P>, C<EV_P_>
		1771
		1772	This provides the loop I<parameter> for functions, if one is required ("ev
		1773	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		1774	C<EV_P_> is used when other parameters are following. Example:
		1775
		1776	// this is how ev_unref is being declared
		1777	static void ev_unref (EV_P);
		1778
		1779	// this is how you can declare your typical callback
		1780	static void cb (EV_P_ ev_timer *w, int revents)
		1781
		1782	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		1783	suitable for use with C<EV_A>.
		1784
		1785	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		1786
		1787	Similar to the other two macros, this gives you the value of the default
		1788	loop, if multiple loops are supported ("ev loop default").
		1789
		1790	=back
		1791
		1792	Example: Declare and initialise a check watcher, working regardless of
		1793	wether multiple loops are supported or not.
		1794
		1795	static void
		1796	check_cb (EV_P_ ev_timer *w, int revents)
		1797	{
		1798	ev_check_stop (EV_A_ w);
		1799	}
		1800
		1801	ev_check check;
		1802	ev_check_init (&check, check_cb);
		1803	ev_check_start (EV_DEFAULT_ &check);
		1804	ev_loop (EV_DEFAULT_ 0);
		1805
1489		1806
1490	=head1 EMBEDDING	1807	=head1 EMBEDDING
1491		1808
1492	Libev can (and often is) directly embedded into host	1809	Libev can (and often is) directly embedded into host
1493	applications. Examples of applications that embed it include the Deliantra	1810	applications. Examples of applications that embed it include the Deliantra
…		…
1700	will have the C<struct ev_loop *> as first argument, and you can create	2017	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	2018	additional independent event loops. Otherwise there will be no support
1702	for multiple event loops and there is no first event loop pointer	2019	for multiple event loops and there is no first event loop pointer
1703	argument. Instead, all functions act on the single default loop.	2020	argument. Instead, all functions act on the single default loop.
1704		2021
1705	=item EV_PERIODICS	2022	=item EV_PERIODIC_ENABLE
1706		2023
1707	If undefined or defined to be C<1>, then periodic timers are supported,	2024	If undefined or defined to be C<1>, then periodic timers are supported. If
1708	otherwise not. This saves a few kb of code.	2025	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2026	code.
		2027
		2028	=item EV_EMBED_ENABLE
		2029
		2030	If undefined or defined to be C<1>, then embed watchers are supported. If
		2031	defined to be C<0>, then they are not.
		2032
		2033	=item EV_STAT_ENABLE
		2034
		2035	If undefined or defined to be C<1>, then stat watchers are supported. If
		2036	defined to be C<0>, then they are not.
		2037
		2038	=item EV_FORK_ENABLE
		2039
		2040	If undefined or defined to be C<1>, then fork watchers are supported. If
		2041	defined to be C<0>, then they are not.
		2042
		2043	=item EV_MINIMAL
		2044
		2045	If you need to shave off some kilobytes of code at the expense of some
		2046	speed, define this symbol to C<1>. Currently only used for gcc to override
		2047	some inlining decisions, saves roughly 30% codesize of amd64.
		2048
		2049	=item EV_PID_HASHSIZE
		2050
		2051	C<ev_child> watchers use a small hash table to distribute workload by
		2052	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2053	than enough. If you need to manage thousands of children you might want to
		2054	increase this value.
1709		2055
1710	=item EV_COMMON	2056	=item EV_COMMON
1711		2057
1712	By default, all watchers have a C<void *data> member. By redefining	2058	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	2059	this macro to a something else you can include more and other types of

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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 1.54 by root, Tue Nov 27 20:26:51 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 1.54 by root, Tue Nov 27 20:26:51 2007 UTC