[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 1.57 by root, Wed Nov 28 11:27:29 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
…		…
644	events but its callback has not yet been invoked). As long as a watcher	703	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	704	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	705	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).	706	libev (e.g. you cnanot C<free ()> it).
648		707
649	=item callback = ev_cb (ev_TYPE *watcher)	708	=item callback ev_cb (ev_TYPE *watcher)
650		709
651	Returns the callback currently set on the watcher.	710	Returns the callback currently set on the watcher.
652		711
653	=item ev_cb_set (ev_TYPE *watcher, callback)	712	=item ev_cb_set (ev_TYPE *watcher, callback)
654		713
…		…
682	{	741	{
683	struct my_io w = (struct my_io )w_;	742	struct my_io w = (struct my_io )w_;
684	...	743	...
685	}	744	}
686		745
687	More interesting and less C-conformant ways of catsing your callback type	746	More interesting and less C-conformant ways of casting your callback type
688	have been omitted....	747	instead have been omitted.
		748
		749	Another common scenario is having some data structure with multiple
		750	watchers:
		751
		752	struct my_biggy
		753	{
		754	int some_data;
		755	ev_timer t1;
		756	ev_timer t2;
		757	}
		758
		759	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		760	you need to use C<offsetof>:
		761
		762	#include <stddef.h>
		763
		764	static void
		765	t1_cb (EV_P_ struct ev_timer *w, int revents)
		766	{
		767	struct my_biggy big = (struct my_biggy *
		768	(((char *)w) - offsetof (struct my_biggy, t1));
		769	}
		770
		771	static void
		772	t2_cb (EV_P_ struct ev_timer *w, int revents)
		773	{
		774	struct my_biggy big = (struct my_biggy *
		775	(((char *)w) - offsetof (struct my_biggy, t2));
		776	}
689		777
690		778
691	=head1 WATCHER TYPES	779	=head1 WATCHER TYPES
692		780
693	This section describes each watcher in detail, but will not repeat	781	This section describes each watcher in detail, but will not repeat
694	information given in the last section.	782	information given in the last section. Any initialisation/set macros,
		783	functions and members specific to the watcher type are explained.
		784
		785	Members are additionally marked with either I<[read-only]>, meaning that,
		786	while the watcher is active, you can look at the member and expect some
		787	sensible content, but you must not modify it (you can modify it while the
		788	watcher is stopped to your hearts content), or I<[read-write]>, which
		789	means you can expect it to have some sensible content while the watcher
		790	is active, but you can also modify it. Modifying it may not do something
		791	sensible or take immediate effect (or do anything at all), but libev will
		792	not crash or malfunction in any way.
695		793
696		794
697	=head2 C<ev_io> - is this file descriptor readable or writable?	795	=head2 C<ev_io> - is this file descriptor readable or writable?
698		796
699	I/O watchers check whether a file descriptor is readable or writable	797	I/O watchers check whether a file descriptor is readable or writable
…		…
742		840
743	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	841	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	842	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.	843	C<EV_READ \| EV_WRITE> to receive the given events.
746		844
		845	=item int fd [read-only]
		846
		847	The file descriptor being watched.
		848
		849	=item int events [read-only]
		850
		851	The events being watched.
		852
747	=back	853	=back
748		854
749	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	855	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	856	readable, but only once. Since it is likely line-buffered, you could
751	attempt to read a whole line in the callback:	857	attempt to read a whole line in the callback.
752		858
753	static void	859	static void
754	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	860	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
755	{	861	{
756	ev_io_stop (loop, w);	862	ev_io_stop (loop, w);
…		…
814		920
815	If the timer is repeating, either start it if necessary (with the repeat	921	If the timer is repeating, either start it if necessary (with the repeat
816	value), or reset the running timer to the repeat value.	922	value), or reset the running timer to the repeat value.
817		923
818	This sounds a bit complicated, but here is a useful and typical	924	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	925	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	926	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	927	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	928	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	929	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	930	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.	931	socket, you can stop the timer, and again will automatically restart it if
		932	need be.
		933
		934	You can also ignore the C<after> value and C<ev_timer_start> altogether
		935	and only ever use the C<repeat> value:
		936
		937	ev_timer_init (timer, callback, 0., 5.);
		938	ev_timer_again (loop, timer);
		939	...
		940	timer->again = 17.;
		941	ev_timer_again (loop, timer);
		942	...
		943	timer->again = 10.;
		944	ev_timer_again (loop, timer);
		945
		946	This is more efficient then stopping/starting the timer eahc time you want
		947	to modify its timeout value.
		948
		949	=item ev_tstamp repeat [read-write]
		950
		951	The current C<repeat> value. Will be used each time the watcher times out
		952	or C<ev_timer_again> is called and determines the next timeout (if any),
		953	which is also when any modifications are taken into account.
826		954
827	=back	955	=back
828		956
829	Example: create a timer that fires after 60 seconds.	957	Example: Create a timer that fires after 60 seconds.
830		958
831	static void	959	static void
832	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	960	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
833	{	961	{
834	.. one minute over, w is actually stopped right here	962	.. one minute over, w is actually stopped right here
…		…
836		964
837	struct ev_timer mytimer;	965	struct ev_timer mytimer;
838	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	966	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
839	ev_timer_start (loop, &mytimer);	967	ev_timer_start (loop, &mytimer);
840		968
841	Example: create a timeout timer that times out after 10 seconds of	969	Example: Create a timeout timer that times out after 10 seconds of
842	inactivity.	970	inactivity.
843		971
844	static void	972	static void
845	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	973	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
846	{	974	{
…		…
957	Simply stops and restarts the periodic watcher again. This is only useful	1085	Simply stops and restarts the periodic watcher again. This is only useful
958	when you changed some parameters or the reschedule callback would return	1086	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	1087	a different time than the last time it was called (e.g. in a crond like
960	program when the crontabs have changed).	1088	program when the crontabs have changed).
961		1089
		1090	=item ev_tstamp interval [read-write]
		1091
		1092	The current interval value. Can be modified any time, but changes only
		1093	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1094	called.
		1095
		1096	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
		1097
		1098	The current reschedule callback, or C<0>, if this functionality is
		1099	switched off. Can be changed any time, but changes only take effect when
		1100	the periodic timer fires or C<ev_periodic_again> is being called.
		1101
962	=back	1102	=back
963		1103
964	Example: call a callback every hour, or, more precisely, whenever the	1104	Example: Call a callback every hour, or, more precisely, whenever the
965	system clock is divisible by 3600. The callback invocation times have	1105	system clock is divisible by 3600. The callback invocation times have
966	potentially a lot of jittering, but good long-term stability.	1106	potentially a lot of jittering, but good long-term stability.
967		1107
968	static void	1108	static void
969	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1109	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
973		1113
974	struct ev_periodic hourly_tick;	1114	struct ev_periodic hourly_tick;
975	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1115	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
976	ev_periodic_start (loop, &hourly_tick);	1116	ev_periodic_start (loop, &hourly_tick);
977		1117
978	Example: the same as above, but use a reschedule callback to do it:	1118	Example: The same as above, but use a reschedule callback to do it:
979		1119
980	#include <math.h>	1120	#include <math.h>
981		1121
982	static ev_tstamp	1122	static ev_tstamp
983	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1123	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
985	return fmod (now, 3600.) + 3600.;	1125	return fmod (now, 3600.) + 3600.;
986	}	1126	}
987		1127
988	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1128	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
989		1129
990	Example: call a callback every hour, starting now:	1130	Example: Call a callback every hour, starting now:
991		1131
992	struct ev_periodic hourly_tick;	1132	struct ev_periodic hourly_tick;
993	ev_periodic_init (&hourly_tick, clock_cb,	1133	ev_periodic_init (&hourly_tick, clock_cb,
994	fmod (ev_now (loop), 3600.), 3600., 0);	1134	fmod (ev_now (loop), 3600.), 3600., 0);
995	ev_periodic_start (loop, &hourly_tick);	1135	ev_periodic_start (loop, &hourly_tick);
…		…
1016	=item ev_signal_set (ev_signal *, int signum)	1156	=item ev_signal_set (ev_signal *, int signum)
1017		1157
1018	Configures the watcher to trigger on the given signal number (usually one	1158	Configures the watcher to trigger on the given signal number (usually one
1019	of the C<SIGxxx> constants).	1159	of the C<SIGxxx> constants).
1020		1160
		1161	=item int signum [read-only]
		1162
		1163	The signal the watcher watches out for.
		1164
1021	=back	1165	=back
1022		1166
1023		1167
1024	=head2 C<ev_child> - watch out for process status changes	1168	=head2 C<ev_child> - watch out for process status changes
1025		1169
…		…
1037	at the C<rstatus> member of the C<ev_child> watcher structure to see	1181	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	1182	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	1183	C<waitpid> documentation). The C<rpid> member contains the pid of the
1040	process causing the status change.	1184	process causing the status change.
1041		1185
		1186	=item int pid [read-only]
		1187
		1188	The process id this watcher watches out for, or C<0>, meaning any process id.
		1189
		1190	=item int rpid [read-write]
		1191
		1192	The process id that detected a status change.
		1193
		1194	=item int rstatus [read-write]
		1195
		1196	The process exit/trace status caused by C<rpid> (see your systems
		1197	C<waitpid> and C<sys/wait.h> documentation for details).
		1198
1042	=back	1199	=back
1043		1200
1044	Example: try to exit cleanly on SIGINT and SIGTERM.	1201	Example: Try to exit cleanly on SIGINT and SIGTERM.
1045		1202
1046	static void	1203	static void
1047	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1204	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1048	{	1205	{
1049	ev_unloop (loop, EVUNLOOP_ALL);	1206	ev_unloop (loop, EVUNLOOP_ALL);
1050	}	1207	}
1051		1208
1052	struct ev_signal signal_watcher;	1209	struct ev_signal signal_watcher;
1053	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1210	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1054	ev_signal_start (loop, &sigint_cb);	1211	ev_signal_start (loop, &sigint_cb);
		1212
		1213
		1214	=head2 C<ev_stat> - did the file attributes just change?
		1215
		1216	This watches a filesystem path for attribute changes. That is, it calls
		1217	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1218	compared to the last time, invoking the callback if it did.
		1219
		1220	The path does not need to exist: changing from "path exists" to "path does
		1221	not exist" is a status change like any other. The condition "path does
		1222	not exist" is signified by the C<st_nlink> field being zero (which is
		1223	otherwise always forced to be at least one) and all the other fields of
		1224	the stat buffer having unspecified contents.
		1225
		1226	Since there is no standard to do this, the portable implementation simply
		1227	calls C<stat (2)> regularly on the path to see if it changed somehow. You
		1228	can specify a recommended polling interval for this case. If you specify
		1229	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1230	unspecified default> value will be used (which you can expect to be around
		1231	five seconds, although this might change dynamically). Libev will also
		1232	impose a minimum interval which is currently around C<0.1>, but thats
		1233	usually overkill.
		1234
		1235	This watcher type is not meant for massive numbers of stat watchers,
		1236	as even with OS-supported change notifications, this can be
		1237	resource-intensive.
		1238
		1239	At the time of this writing, only the Linux inotify interface is
		1240	implemented (implementing kqueue support is left as an exercise for the
		1241	reader). Inotify will be used to give hints only and should not change the
		1242	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1243	to fall back to regular polling again even with inotify, but changes are
		1244	usually detected immediately, and if the file exists there will be no
		1245	polling.
		1246
		1247	=over 4
		1248
		1249	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
		1250
		1251	=item ev_stat_set (ev_stat , const char path, ev_tstamp interval)
		1252
		1253	Configures the watcher to wait for status changes of the given
		1254	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1255	be detected and should normally be specified as C<0> to let libev choose
		1256	a suitable value. The memory pointed to by C<path> must point to the same
		1257	path for as long as the watcher is active.
		1258
		1259	The callback will be receive C<EV_STAT> when a change was detected,
		1260	relative to the attributes at the time the watcher was started (or the
		1261	last change was detected).
		1262
		1263	=item ev_stat_stat (ev_stat *)
		1264
		1265	Updates the stat buffer immediately with new values. If you change the
		1266	watched path in your callback, you could call this fucntion to avoid
		1267	detecting this change (while introducing a race condition). Can also be
		1268	useful simply to find out the new values.
		1269
		1270	=item ev_statdata attr [read-only]
		1271
		1272	The most-recently detected attributes of the file. Although the type is of
		1273	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1274	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1275	was some error while C<stat>ing the file.
		1276
		1277	=item ev_statdata prev [read-only]
		1278
		1279	The previous attributes of the file. The callback gets invoked whenever
		1280	C<prev> != C<attr>.
		1281
		1282	=item ev_tstamp interval [read-only]
		1283
		1284	The specified interval.
		1285
		1286	=item const char *path [read-only]
		1287
		1288	The filesystem path that is being watched.
		1289
		1290	=back
		1291
		1292	Example: Watch C</etc/passwd> for attribute changes.
		1293
		1294	static void
		1295	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1296	{
		1297	/* /etc/passwd changed in some way */
		1298	if (w->attr.st_nlink)
		1299	{
		1300	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1301	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1302	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1303	}
		1304	else
		1305	/* you shalt not abuse printf for puts */
		1306	puts ("wow, /etc/passwd is not there, expect problems. "
		1307	"if this is windows, they already arrived\n");
		1308	}
		1309
		1310	...
		1311	ev_stat passwd;
		1312
		1313	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1314	ev_stat_start (loop, &passwd);
1055		1315
1056		1316
1057	=head2 C<ev_idle> - when you've got nothing better to do...	1317	=head2 C<ev_idle> - when you've got nothing better to do...
1058		1318
1059	Idle watchers trigger events when there are no other events are pending	1319	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,	1340	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1081	believe me.	1341	believe me.
1082		1342
1083	=back	1343	=back
1084		1344
1085	Example: dynamically allocate an C<ev_idle>, start it, and in the	1345	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1086	callback, free it. Alos, use no error checking, as usual.	1346	callback, free it. Also, use no error checking, as usual.
1087		1347
1088	static void	1348	static void
1089	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1349	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1090	{	1350	{
1091	free (w);	1351	free (w);
…		…
1292		1552
1293	Make a single, non-blocking sweep over the embedded loop. This works	1553	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	1554	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1295	apropriate way for embedded loops.	1555	apropriate way for embedded loops.
1296		1556
		1557	=item struct ev_loop *loop [read-only]
		1558
		1559	The embedded event loop.
		1560
		1561	=back
		1562
		1563
		1564	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1565
		1566	Fork watchers are called when a C<fork ()> was detected (usually because
		1567	whoever is a good citizen cared to tell libev about it by calling
		1568	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1569	event loop blocks next and before C<ev_check> watchers are being called,
		1570	and only in the child after the fork. If whoever good citizen calling
		1571	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1572	handlers will be invoked, too, of course.
		1573
		1574	=over 4
		1575
		1576	=item ev_fork_init (ev_signal *, callback)
		1577
		1578	Initialises and configures the fork watcher - it has no parameters of any
		1579	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1580	believe me.
		1581
1297	=back	1582	=back
1298		1583
1299		1584
1300	=head1 OTHER FUNCTIONS	1585	=head1 OTHER FUNCTIONS
1301		1586
…		…
1463		1748
1464	=item w->sweep () C<ev::embed> only	1749	=item w->sweep () C<ev::embed> only
1465		1750
1466	Invokes C<ev_embed_sweep>.	1751	Invokes C<ev_embed_sweep>.
1467		1752
		1753	=item w->update () C<ev::stat> only
		1754
		1755	Invokes C<ev_stat_stat>.
		1756
1468	=back	1757	=back
1469		1758
1470	=back	1759	=back
1471		1760
1472	Example: Define a class with an IO and idle watcher, start one of them in	1761	Example: Define a class with an IO and idle watcher, start one of them in
…		…
1484	: io (this, &myclass::io_cb),	1773	: io (this, &myclass::io_cb),
1485	idle (this, &myclass::idle_cb)	1774	idle (this, &myclass::idle_cb)
1486	{	1775	{
1487	io.start (fd, ev::READ);	1776	io.start (fd, ev::READ);
1488	}	1777	}
		1778
		1779
		1780	=head1 MACRO MAGIC
		1781
		1782	Libev can be compiled with a variety of options, the most fundemantal is
		1783	C<EV_MULTIPLICITY>. This option determines wether (most) functions and
		1784	callbacks have an initial C<struct ev_loop *> argument.
		1785
		1786	To make it easier to write programs that cope with either variant, the
		1787	following macros are defined:
		1788
		1789	=over 4
		1790
		1791	=item C<EV_A>, C<EV_A_>
		1792
		1793	This provides the loop I<argument> for functions, if one is required ("ev
		1794	loop argument"). The C<EV_A> form is used when this is the sole argument,
		1795	C<EV_A_> is used when other arguments are following. Example:
		1796
		1797	ev_unref (EV_A);
		1798	ev_timer_add (EV_A_ watcher);
		1799	ev_loop (EV_A_ 0);
		1800
		1801	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		1802	which is often provided by the following macro.
		1803
		1804	=item C<EV_P>, C<EV_P_>
		1805
		1806	This provides the loop I<parameter> for functions, if one is required ("ev
		1807	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		1808	C<EV_P_> is used when other parameters are following. Example:
		1809
		1810	// this is how ev_unref is being declared
		1811	static void ev_unref (EV_P);
		1812
		1813	// this is how you can declare your typical callback
		1814	static void cb (EV_P_ ev_timer *w, int revents)
		1815
		1816	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		1817	suitable for use with C<EV_A>.
		1818
		1819	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		1820
		1821	Similar to the other two macros, this gives you the value of the default
		1822	loop, if multiple loops are supported ("ev loop default").
		1823
		1824	=back
		1825
		1826	Example: Declare and initialise a check watcher, working regardless of
		1827	wether multiple loops are supported or not.
		1828
		1829	static void
		1830	check_cb (EV_P_ ev_timer *w, int revents)
		1831	{
		1832	ev_check_stop (EV_A_ w);
		1833	}
		1834
		1835	ev_check check;
		1836	ev_check_init (&check, check_cb);
		1837	ev_check_start (EV_DEFAULT_ &check);
		1838	ev_loop (EV_DEFAULT_ 0);
		1839
1489		1840
1490	=head1 EMBEDDING	1841	=head1 EMBEDDING
1491		1842
1492	Libev can (and often is) directly embedded into host	1843	Libev can (and often is) directly embedded into host
1493	applications. Examples of applications that embed it include the Deliantra	1844	applications. Examples of applications that embed it include the Deliantra
…		…
1668		2019
1669	=item EV_USE_DEVPOLL	2020	=item EV_USE_DEVPOLL
1670		2021
1671	reserved for future expansion, works like the USE symbols above.	2022	reserved for future expansion, works like the USE symbols above.
1672		2023
		2024	=item EV_USE_INOTIFY
		2025
		2026	If defined to be C<1>, libev will compile in support for the Linux inotify
		2027	interface to speed up C<ev_stat> watchers. Its actual availability will
		2028	be detected at runtime.
		2029
1673	=item EV_H	2030	=item EV_H
1674		2031
1675	The name of the F<ev.h> header file used to include it. The default if	2032	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	2033	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.	2034	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	2057	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	2058	additional independent event loops. Otherwise there will be no support
1702	for multiple event loops and there is no first event loop pointer	2059	for multiple event loops and there is no first event loop pointer
1703	argument. Instead, all functions act on the single default loop.	2060	argument. Instead, all functions act on the single default loop.
1704		2061
1705	=item EV_PERIODICS	2062	=item EV_PERIODIC_ENABLE
1706		2063
1707	If undefined or defined to be C<1>, then periodic timers are supported,	2064	If undefined or defined to be C<1>, then periodic timers are supported. If
1708	otherwise not. This saves a few kb of code.	2065	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2066	code.
		2067
		2068	=item EV_EMBED_ENABLE
		2069
		2070	If undefined or defined to be C<1>, then embed watchers are supported. If
		2071	defined to be C<0>, then they are not.
		2072
		2073	=item EV_STAT_ENABLE
		2074
		2075	If undefined or defined to be C<1>, then stat watchers are supported. If
		2076	defined to be C<0>, then they are not.
		2077
		2078	=item EV_FORK_ENABLE
		2079
		2080	If undefined or defined to be C<1>, then fork watchers are supported. If
		2081	defined to be C<0>, then they are not.
		2082
		2083	=item EV_MINIMAL
		2084
		2085	If you need to shave off some kilobytes of code at the expense of some
		2086	speed, define this symbol to C<1>. Currently only used for gcc to override
		2087	some inlining decisions, saves roughly 30% codesize of amd64.
		2088
		2089	=item EV_PID_HASHSIZE
		2090
		2091	C<ev_child> watchers use a small hash table to distribute workload by
		2092	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2093	than enough. If you need to manage thousands of children you might want to
		2094	increase this value (I<must> be a power of two).
		2095
		2096	=item EV_INOTIFY_HASHSIZE
		2097
		2098	C<ev_staz> watchers use a small hash table to distribute workload by
		2099	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2100	usually more than enough. If you need to manage thousands of C<ev_stat>
		2101	watchers you might want to increase this value (I<must> be a power of
		2102	two).
1709		2103
1710	=item EV_COMMON	2104	=item EV_COMMON
1711		2105
1712	By default, all watchers have a C<void *data> member. By redefining	2106	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	2107	this macro to a something else you can include more and other types of
…		…
1773		2167
1774	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2168	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
1775		2169
1776	=item Stopping check/prepare/idle watchers: O(1)	2170	=item Stopping check/prepare/idle watchers: O(1)
1777		2171
1778	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2172	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
1779		2173
1780	=item Finding the next timer per loop iteration: O(1)	2174	=item Finding the next timer per loop iteration: O(1)
1781		2175
1782	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2176	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
1783		2177

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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 1.57 by root, Wed Nov 28 11:27:29 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 1.57 by root, Wed Nov 28 11:27:29 2007 UTC