[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 1.60 by root, Wed Nov 28 18:29:30 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
…		…
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, long 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 is similar - the
124	realloc C function, the semantics are identical). It is used to allocate	171	semantics is identical - to the realloc C function). It is used to
125	and free memory (no surprises here). If it returns zero when memory	172	allocate and free memory (no surprises here). If it returns zero when
126	needs to be allocated, the library might abort or take some potentially	173	memory needs to be allocated, the library might abort or take some
127	destructive action. The default is your system realloc function.	174	potentially destructive action. The default is your system realloc
		175	function.
128		176
129	You could override this function in high-availability programs to, say,	177	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,	178	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.	179	or even to sleep a while and retry until some memory is available.
132		180
133	Example: replace the libev allocator with one that waits a bit and then	181	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	182	retries).
135		183
136	static void *	184	static void *
137	persistent_realloc (void *ptr, long size)	185	persistent_realloc (void *ptr, size_t size)
138	{	186	{
139	for (;;)	187	for (;;)
140	{	188	{
141	void *newptr = realloc (ptr, size);	189	void *newptr = realloc (ptr, size);
142		190
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	206	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	207	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	208	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	209	(such as abort).
162		210
163	Example: do the same thing as libev does internally:	211	Example: This is basically the same thing that libev does internally, too.
164		212
165	static void	213	static void
166	fatal_error (const char *msg)	214	fatal_error (const char *msg)
167	{	215	{
168	perror (msg);	216	perror (msg);
…		…
314	Similar to C<ev_default_loop>, but always creates a new event loop that is	362	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	363	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	364	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).	365	undefined behaviour (or a failed assertion if assertions are enabled).
318		366
319	Example: try to create a event loop that uses epoll and nothing else.	367	Example: Try to create a event loop that uses epoll and nothing else.
320		368
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	369	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
322	if (!epoller)	370	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	371	fatal ("no epoll found here, maybe it hides under your chair");
324		372
…		…
423	Signals and child watchers are implemented as I/O watchers, and will	471	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	472	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	473	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	474	were used, return, otherwise continue with step *.
427		475
428	Example: queue some jobs and then loop until no events are outsanding	476	Example: Queue some jobs and then loop until no events are outsanding
429	anymore.	477	anymore.
430		478
431	... queue jobs here, make sure they register event watchers as long	479	... 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..)	480	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	481	ev_loop (my_loop, 0);
…		…
453	visible to the libev user and should not keep C<ev_loop> from exiting if	501	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	502	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	503	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>.	504	libraries. Just remember to I<unref after start> and I<ref before stop>.
457		505
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	506	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	507	running when nothing else is active.
460		508
461	struct dv_signal exitsig;	509	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	510	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	511	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	512	evf_unref (loop);
465		513
466	Example: for some weird reason, unregister the above signal handler again.	514	Example: For some weird reason, unregister the above signal handler again.
467		515
468	ev_ref (myloop);	516	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	517	ev_signal_stop (loop, &exitsig);
470		518
471	=back	519	=back
472		520
473		521
474	=head1 ANATOMY OF A WATCHER	522	=head1 ANATOMY OF A WATCHER
…		…
544	The signal specified in the C<ev_signal> watcher has been received by a thread.	592	The signal specified in the C<ev_signal> watcher has been received by a thread.
545		593
546	=item C<EV_CHILD>	594	=item C<EV_CHILD>
547		595
548	The pid specified in the C<ev_child> watcher has received a status change.	596	The pid specified in the C<ev_child> watcher has received a status change.
		597
		598	=item C<EV_STAT>
		599
		600	The path specified in the C<ev_stat> watcher changed its attributes somehow.
549		601
550	=item C<EV_IDLE>	602	=item C<EV_IDLE>
551		603
552	The C<ev_idle> watcher has determined that you have nothing better to do.	604	The C<ev_idle> watcher has determined that you have nothing better to do.
553		605
…		…
561	received events. Callbacks of both watcher types can start and stop as	613	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	614	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	615	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
564	C<ev_loop> from blocking).	616	C<ev_loop> from blocking).
565		617
		618	=item C<EV_EMBED>
		619
		620	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		621
		622	=item C<EV_FORK>
		623
		624	The event loop has been resumed in the child process after fork (see
		625	C<ev_fork>).
		626
566	=item C<EV_ERROR>	627	=item C<EV_ERROR>
567		628
568	An unspecified error has occured, the watcher has been stopped. This might	629	An unspecified error has occured, the watcher has been stopped. This might
569	happen because the watcher could not be properly started because libev	630	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	631	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	705	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	706	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	707	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).	708	libev (e.g. you cnanot C<free ()> it).
648		709
649	=item callback = ev_cb (ev_TYPE *watcher)	710	=item callback ev_cb (ev_TYPE *watcher)
650		711
651	Returns the callback currently set on the watcher.	712	Returns the callback currently set on the watcher.
652		713
653	=item ev_cb_set (ev_TYPE *watcher, callback)	714	=item ev_cb_set (ev_TYPE *watcher, callback)
654		715
…		…
682	{	743	{
683	struct my_io w = (struct my_io )w_;	744	struct my_io w = (struct my_io )w_;
684	...	745	...
685	}	746	}
686		747
687	More interesting and less C-conformant ways of catsing your callback type	748	More interesting and less C-conformant ways of casting your callback type
688	have been omitted....	749	instead have been omitted.
		750
		751	Another common scenario is having some data structure with multiple
		752	watchers:
		753
		754	struct my_biggy
		755	{
		756	int some_data;
		757	ev_timer t1;
		758	ev_timer t2;
		759	}
		760
		761	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		762	you need to use C<offsetof>:
		763
		764	#include <stddef.h>
		765
		766	static void
		767	t1_cb (EV_P_ struct ev_timer *w, int revents)
		768	{
		769	struct my_biggy big = (struct my_biggy *
		770	(((char *)w) - offsetof (struct my_biggy, t1));
		771	}
		772
		773	static void
		774	t2_cb (EV_P_ struct ev_timer *w, int revents)
		775	{
		776	struct my_biggy big = (struct my_biggy *
		777	(((char *)w) - offsetof (struct my_biggy, t2));
		778	}
689		779
690		780
691	=head1 WATCHER TYPES	781	=head1 WATCHER TYPES
692		782
693	This section describes each watcher in detail, but will not repeat	783	This section describes each watcher in detail, but will not repeat
694	information given in the last section.	784	information given in the last section. Any initialisation/set macros,
		785	functions and members specific to the watcher type are explained.
		786
		787	Members are additionally marked with either I<[read-only]>, meaning that,
		788	while the watcher is active, you can look at the member and expect some
		789	sensible content, but you must not modify it (you can modify it while the
		790	watcher is stopped to your hearts content), or I<[read-write]>, which
		791	means you can expect it to have some sensible content while the watcher
		792	is active, but you can also modify it. Modifying it may not do something
		793	sensible or take immediate effect (or do anything at all), but libev will
		794	not crash or malfunction in any way.
695		795
696		796
697	=head2 C<ev_io> - is this file descriptor readable or writable?	797	=head2 C<ev_io> - is this file descriptor readable or writable?
698		798
699	I/O watchers check whether a file descriptor is readable or writable	799	I/O watchers check whether a file descriptor is readable or writable
…		…
742		842
743	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	843	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	844	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.	845	C<EV_READ \| EV_WRITE> to receive the given events.
746		846
		847	=item int fd [read-only]
		848
		849	The file descriptor being watched.
		850
		851	=item int events [read-only]
		852
		853	The events being watched.
		854
747	=back	855	=back
748		856
749	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	857	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	858	readable, but only once. Since it is likely line-buffered, you could
751	attempt to read a whole line in the callback:	859	attempt to read a whole line in the callback.
752		860
753	static void	861	static void
754	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	862	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
755	{	863	{
756	ev_io_stop (loop, w);	864	ev_io_stop (loop, w);
…		…
814		922
815	If the timer is repeating, either start it if necessary (with the repeat	923	If the timer is repeating, either start it if necessary (with the repeat
816	value), or reset the running timer to the repeat value.	924	value), or reset the running timer to the repeat value.
817		925
818	This sounds a bit complicated, but here is a useful and typical	926	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	927	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	928	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	929	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	930	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	931	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	932	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.	933	socket, you can stop the timer, and again will automatically restart it if
		934	need be.
		935
		936	You can also ignore the C<after> value and C<ev_timer_start> altogether
		937	and only ever use the C<repeat> value:
		938
		939	ev_timer_init (timer, callback, 0., 5.);
		940	ev_timer_again (loop, timer);
		941	...
		942	timer->again = 17.;
		943	ev_timer_again (loop, timer);
		944	...
		945	timer->again = 10.;
		946	ev_timer_again (loop, timer);
		947
		948	This is more efficient then stopping/starting the timer eahc time you want
		949	to modify its timeout value.
		950
		951	=item ev_tstamp repeat [read-write]
		952
		953	The current C<repeat> value. Will be used each time the watcher times out
		954	or C<ev_timer_again> is called and determines the next timeout (if any),
		955	which is also when any modifications are taken into account.
826		956
827	=back	957	=back
828		958
829	Example: create a timer that fires after 60 seconds.	959	Example: Create a timer that fires after 60 seconds.
830		960
831	static void	961	static void
832	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	962	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
833	{	963	{
834	.. one minute over, w is actually stopped right here	964	.. one minute over, w is actually stopped right here
…		…
836		966
837	struct ev_timer mytimer;	967	struct ev_timer mytimer;
838	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	968	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
839	ev_timer_start (loop, &mytimer);	969	ev_timer_start (loop, &mytimer);
840		970
841	Example: create a timeout timer that times out after 10 seconds of	971	Example: Create a timeout timer that times out after 10 seconds of
842	inactivity.	972	inactivity.
843		973
844	static void	974	static void
845	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	975	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
846	{	976	{
…		…
957	Simply stops and restarts the periodic watcher again. This is only useful	1087	Simply stops and restarts the periodic watcher again. This is only useful
958	when you changed some parameters or the reschedule callback would return	1088	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	1089	a different time than the last time it was called (e.g. in a crond like
960	program when the crontabs have changed).	1090	program when the crontabs have changed).
961		1091
		1092	=item ev_tstamp interval [read-write]
		1093
		1094	The current interval value. Can be modified any time, but changes only
		1095	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1096	called.
		1097
		1098	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
		1099
		1100	The current reschedule callback, or C<0>, if this functionality is
		1101	switched off. Can be changed any time, but changes only take effect when
		1102	the periodic timer fires or C<ev_periodic_again> is being called.
		1103
962	=back	1104	=back
963		1105
964	Example: call a callback every hour, or, more precisely, whenever the	1106	Example: Call a callback every hour, or, more precisely, whenever the
965	system clock is divisible by 3600. The callback invocation times have	1107	system clock is divisible by 3600. The callback invocation times have
966	potentially a lot of jittering, but good long-term stability.	1108	potentially a lot of jittering, but good long-term stability.
967		1109
968	static void	1110	static void
969	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1111	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
973		1115
974	struct ev_periodic hourly_tick;	1116	struct ev_periodic hourly_tick;
975	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1117	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
976	ev_periodic_start (loop, &hourly_tick);	1118	ev_periodic_start (loop, &hourly_tick);
977		1119
978	Example: the same as above, but use a reschedule callback to do it:	1120	Example: The same as above, but use a reschedule callback to do it:
979		1121
980	#include <math.h>	1122	#include <math.h>
981		1123
982	static ev_tstamp	1124	static ev_tstamp
983	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1125	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
985	return fmod (now, 3600.) + 3600.;	1127	return fmod (now, 3600.) + 3600.;
986	}	1128	}
987		1129
988	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1130	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
989		1131
990	Example: call a callback every hour, starting now:	1132	Example: Call a callback every hour, starting now:
991		1133
992	struct ev_periodic hourly_tick;	1134	struct ev_periodic hourly_tick;
993	ev_periodic_init (&hourly_tick, clock_cb,	1135	ev_periodic_init (&hourly_tick, clock_cb,
994	fmod (ev_now (loop), 3600.), 3600., 0);	1136	fmod (ev_now (loop), 3600.), 3600., 0);
995	ev_periodic_start (loop, &hourly_tick);	1137	ev_periodic_start (loop, &hourly_tick);
…		…
1016	=item ev_signal_set (ev_signal *, int signum)	1158	=item ev_signal_set (ev_signal *, int signum)
1017		1159
1018	Configures the watcher to trigger on the given signal number (usually one	1160	Configures the watcher to trigger on the given signal number (usually one
1019	of the C<SIGxxx> constants).	1161	of the C<SIGxxx> constants).
1020		1162
		1163	=item int signum [read-only]
		1164
		1165	The signal the watcher watches out for.
		1166
1021	=back	1167	=back
1022		1168
1023		1169
1024	=head2 C<ev_child> - watch out for process status changes	1170	=head2 C<ev_child> - watch out for process status changes
1025		1171
…		…
1037	at the C<rstatus> member of the C<ev_child> watcher structure to see	1183	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	1184	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	1185	C<waitpid> documentation). The C<rpid> member contains the pid of the
1040	process causing the status change.	1186	process causing the status change.
1041		1187
		1188	=item int pid [read-only]
		1189
		1190	The process id this watcher watches out for, or C<0>, meaning any process id.
		1191
		1192	=item int rpid [read-write]
		1193
		1194	The process id that detected a status change.
		1195
		1196	=item int rstatus [read-write]
		1197
		1198	The process exit/trace status caused by C<rpid> (see your systems
		1199	C<waitpid> and C<sys/wait.h> documentation for details).
		1200
1042	=back	1201	=back
1043		1202
1044	Example: try to exit cleanly on SIGINT and SIGTERM.	1203	Example: Try to exit cleanly on SIGINT and SIGTERM.
1045		1204
1046	static void	1205	static void
1047	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1206	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1048	{	1207	{
1049	ev_unloop (loop, EVUNLOOP_ALL);	1208	ev_unloop (loop, EVUNLOOP_ALL);
1050	}	1209	}
1051		1210
1052	struct ev_signal signal_watcher;	1211	struct ev_signal signal_watcher;
1053	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1212	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1054	ev_signal_start (loop, &sigint_cb);	1213	ev_signal_start (loop, &sigint_cb);
		1214
		1215
		1216	=head2 C<ev_stat> - did the file attributes just change?
		1217
		1218	This watches a filesystem path for attribute changes. That is, it calls
		1219	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1220	compared to the last time, invoking the callback if it did.
		1221
		1222	The path does not need to exist: changing from "path exists" to "path does
		1223	not exist" is a status change like any other. The condition "path does
		1224	not exist" is signified by the C<st_nlink> field being zero (which is
		1225	otherwise always forced to be at least one) and all the other fields of
		1226	the stat buffer having unspecified contents.
		1227
		1228	The path I<should> be absolute and I<must not> end in a slash. If it is
		1229	relative and your working directory changes, the behaviour is undefined.
		1230
		1231	Since there is no standard to do this, the portable implementation simply
		1232	calls C<stat (2)> regularly on the path to see if it changed somehow. You
		1233	can specify a recommended polling interval for this case. If you specify
		1234	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1235	unspecified default> value will be used (which you can expect to be around
		1236	five seconds, although this might change dynamically). Libev will also
		1237	impose a minimum interval which is currently around C<0.1>, but thats
		1238	usually overkill.
		1239
		1240	This watcher type is not meant for massive numbers of stat watchers,
		1241	as even with OS-supported change notifications, this can be
		1242	resource-intensive.
		1243
		1244	At the time of this writing, only the Linux inotify interface is
		1245	implemented (implementing kqueue support is left as an exercise for the
		1246	reader). Inotify will be used to give hints only and should not change the
		1247	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1248	to fall back to regular polling again even with inotify, but changes are
		1249	usually detected immediately, and if the file exists there will be no
		1250	polling.
		1251
		1252	=over 4
		1253
		1254	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
		1255
		1256	=item ev_stat_set (ev_stat , const char path, ev_tstamp interval)
		1257
		1258	Configures the watcher to wait for status changes of the given
		1259	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1260	be detected and should normally be specified as C<0> to let libev choose
		1261	a suitable value. The memory pointed to by C<path> must point to the same
		1262	path for as long as the watcher is active.
		1263
		1264	The callback will be receive C<EV_STAT> when a change was detected,
		1265	relative to the attributes at the time the watcher was started (or the
		1266	last change was detected).
		1267
		1268	=item ev_stat_stat (ev_stat *)
		1269
		1270	Updates the stat buffer immediately with new values. If you change the
		1271	watched path in your callback, you could call this fucntion to avoid
		1272	detecting this change (while introducing a race condition). Can also be
		1273	useful simply to find out the new values.
		1274
		1275	=item ev_statdata attr [read-only]
		1276
		1277	The most-recently detected attributes of the file. Although the type is of
		1278	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1279	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1280	was some error while C<stat>ing the file.
		1281
		1282	=item ev_statdata prev [read-only]
		1283
		1284	The previous attributes of the file. The callback gets invoked whenever
		1285	C<prev> != C<attr>.
		1286
		1287	=item ev_tstamp interval [read-only]
		1288
		1289	The specified interval.
		1290
		1291	=item const char *path [read-only]
		1292
		1293	The filesystem path that is being watched.
		1294
		1295	=back
		1296
		1297	Example: Watch C</etc/passwd> for attribute changes.
		1298
		1299	static void
		1300	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1301	{
		1302	/* /etc/passwd changed in some way */
		1303	if (w->attr.st_nlink)
		1304	{
		1305	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1306	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1307	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1308	}
		1309	else
		1310	/* you shalt not abuse printf for puts */
		1311	puts ("wow, /etc/passwd is not there, expect problems. "
		1312	"if this is windows, they already arrived\n");
		1313	}
		1314
		1315	...
		1316	ev_stat passwd;
		1317
		1318	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1319	ev_stat_start (loop, &passwd);
1055		1320
1056		1321
1057	=head2 C<ev_idle> - when you've got nothing better to do...	1322	=head2 C<ev_idle> - when you've got nothing better to do...
1058		1323
1059	Idle watchers trigger events when there are no other events are pending	1324	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,	1345	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1081	believe me.	1346	believe me.
1082		1347
1083	=back	1348	=back
1084		1349
1085	Example: dynamically allocate an C<ev_idle>, start it, and in the	1350	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1086	callback, free it. Alos, use no error checking, as usual.	1351	callback, free it. Also, use no error checking, as usual.
1087		1352
1088	static void	1353	static void
1089	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1354	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1090	{	1355	{
1091	free (w);	1356	free (w);
…		…
1292		1557
1293	Make a single, non-blocking sweep over the embedded loop. This works	1558	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	1559	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1295	apropriate way for embedded loops.	1560	apropriate way for embedded loops.
1296		1561
		1562	=item struct ev_loop *loop [read-only]
		1563
		1564	The embedded event loop.
		1565
		1566	=back
		1567
		1568
		1569	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1570
		1571	Fork watchers are called when a C<fork ()> was detected (usually because
		1572	whoever is a good citizen cared to tell libev about it by calling
		1573	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1574	event loop blocks next and before C<ev_check> watchers are being called,
		1575	and only in the child after the fork. If whoever good citizen calling
		1576	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1577	handlers will be invoked, too, of course.
		1578
		1579	=over 4
		1580
		1581	=item ev_fork_init (ev_signal *, callback)
		1582
		1583	Initialises and configures the fork watcher - it has no parameters of any
		1584	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1585	believe me.
		1586
1297	=back	1587	=back
1298		1588
1299		1589
1300	=head1 OTHER FUNCTIONS	1590	=head1 OTHER FUNCTIONS
1301		1591
…		…
1463		1753
1464	=item w->sweep () C<ev::embed> only	1754	=item w->sweep () C<ev::embed> only
1465		1755
1466	Invokes C<ev_embed_sweep>.	1756	Invokes C<ev_embed_sweep>.
1467		1757
		1758	=item w->update () C<ev::stat> only
		1759
		1760	Invokes C<ev_stat_stat>.
		1761
1468	=back	1762	=back
1469		1763
1470	=back	1764	=back
1471		1765
1472	Example: Define a class with an IO and idle watcher, start one of them in	1766	Example: Define a class with an IO and idle watcher, start one of them in
…		…
1484	: io (this, &myclass::io_cb),	1778	: io (this, &myclass::io_cb),
1485	idle (this, &myclass::idle_cb)	1779	idle (this, &myclass::idle_cb)
1486	{	1780	{
1487	io.start (fd, ev::READ);	1781	io.start (fd, ev::READ);
1488	}	1782	}
		1783
		1784
		1785	=head1 MACRO MAGIC
		1786
		1787	Libev can be compiled with a variety of options, the most fundemantal is
		1788	C<EV_MULTIPLICITY>. This option determines wether (most) functions and
		1789	callbacks have an initial C<struct ev_loop *> argument.
		1790
		1791	To make it easier to write programs that cope with either variant, the
		1792	following macros are defined:
		1793
		1794	=over 4
		1795
		1796	=item C<EV_A>, C<EV_A_>
		1797
		1798	This provides the loop I<argument> for functions, if one is required ("ev
		1799	loop argument"). The C<EV_A> form is used when this is the sole argument,
		1800	C<EV_A_> is used when other arguments are following. Example:
		1801
		1802	ev_unref (EV_A);
		1803	ev_timer_add (EV_A_ watcher);
		1804	ev_loop (EV_A_ 0);
		1805
		1806	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		1807	which is often provided by the following macro.
		1808
		1809	=item C<EV_P>, C<EV_P_>
		1810
		1811	This provides the loop I<parameter> for functions, if one is required ("ev
		1812	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		1813	C<EV_P_> is used when other parameters are following. Example:
		1814
		1815	// this is how ev_unref is being declared
		1816	static void ev_unref (EV_P);
		1817
		1818	// this is how you can declare your typical callback
		1819	static void cb (EV_P_ ev_timer *w, int revents)
		1820
		1821	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		1822	suitable for use with C<EV_A>.
		1823
		1824	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		1825
		1826	Similar to the other two macros, this gives you the value of the default
		1827	loop, if multiple loops are supported ("ev loop default").
		1828
		1829	=back
		1830
		1831	Example: Declare and initialise a check watcher, working regardless of
		1832	wether multiple loops are supported or not.
		1833
		1834	static void
		1835	check_cb (EV_P_ ev_timer *w, int revents)
		1836	{
		1837	ev_check_stop (EV_A_ w);
		1838	}
		1839
		1840	ev_check check;
		1841	ev_check_init (&check, check_cb);
		1842	ev_check_start (EV_DEFAULT_ &check);
		1843	ev_loop (EV_DEFAULT_ 0);
		1844
1489		1845
1490	=head1 EMBEDDING	1846	=head1 EMBEDDING
1491		1847
1492	Libev can (and often is) directly embedded into host	1848	Libev can (and often is) directly embedded into host
1493	applications. Examples of applications that embed it include the Deliantra	1849	applications. Examples of applications that embed it include the Deliantra
…		…
1668		2024
1669	=item EV_USE_DEVPOLL	2025	=item EV_USE_DEVPOLL
1670		2026
1671	reserved for future expansion, works like the USE symbols above.	2027	reserved for future expansion, works like the USE symbols above.
1672		2028
		2029	=item EV_USE_INOTIFY
		2030
		2031	If defined to be C<1>, libev will compile in support for the Linux inotify
		2032	interface to speed up C<ev_stat> watchers. Its actual availability will
		2033	be detected at runtime.
		2034
1673	=item EV_H	2035	=item EV_H
1674		2036
1675	The name of the F<ev.h> header file used to include it. The default if	2037	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	2038	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.	2039	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	2062	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	2063	additional independent event loops. Otherwise there will be no support
1702	for multiple event loops and there is no first event loop pointer	2064	for multiple event loops and there is no first event loop pointer
1703	argument. Instead, all functions act on the single default loop.	2065	argument. Instead, all functions act on the single default loop.
1704		2066
1705	=item EV_PERIODICS	2067	=item EV_PERIODIC_ENABLE
1706		2068
1707	If undefined or defined to be C<1>, then periodic timers are supported,	2069	If undefined or defined to be C<1>, then periodic timers are supported. If
1708	otherwise not. This saves a few kb of code.	2070	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2071	code.
		2072
		2073	=item EV_EMBED_ENABLE
		2074
		2075	If undefined or defined to be C<1>, then embed watchers are supported. If
		2076	defined to be C<0>, then they are not.
		2077
		2078	=item EV_STAT_ENABLE
		2079
		2080	If undefined or defined to be C<1>, then stat watchers are supported. If
		2081	defined to be C<0>, then they are not.
		2082
		2083	=item EV_FORK_ENABLE
		2084
		2085	If undefined or defined to be C<1>, then fork watchers are supported. If
		2086	defined to be C<0>, then they are not.
		2087
		2088	=item EV_MINIMAL
		2089
		2090	If you need to shave off some kilobytes of code at the expense of some
		2091	speed, define this symbol to C<1>. Currently only used for gcc to override
		2092	some inlining decisions, saves roughly 30% codesize of amd64.
		2093
		2094	=item EV_PID_HASHSIZE
		2095
		2096	C<ev_child> watchers use a small hash table to distribute workload by
		2097	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2098	than enough. If you need to manage thousands of children you might want to
		2099	increase this value (I<must> be a power of two).
		2100
		2101	=item EV_INOTIFY_HASHSIZE
		2102
		2103	C<ev_staz> watchers use a small hash table to distribute workload by
		2104	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2105	usually more than enough. If you need to manage thousands of C<ev_stat>
		2106	watchers you might want to increase this value (I<must> be a power of
		2107	two).
1709		2108
1710	=item EV_COMMON	2109	=item EV_COMMON
1711		2110
1712	By default, all watchers have a C<void *data> member. By redefining	2111	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	2112	this macro to a something else you can include more and other types of
…		…
1773		2172
1774	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2173	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
1775		2174
1776	=item Stopping check/prepare/idle watchers: O(1)	2175	=item Stopping check/prepare/idle watchers: O(1)
1777		2176
1778	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2177	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
1779		2178
1780	=item Finding the next timer per loop iteration: O(1)	2179	=item Finding the next timer per loop iteration: O(1)
1781		2180
1782	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2181	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
1783		2182

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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 1.60 by root, Wed Nov 28 18:29:30 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 1.60 by root, Wed Nov 28 18:29:30 2007 UTC