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

Comparing libev/ev.pod (file contents):
Revision 1.53 by root, Tue Nov 27 20:15:02 2007 UTC vs.
Revision 1.67 by root, Fri Dec 7 16:44:12 2007 UTC

…		…
2		2
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	/* this is the only header you need */
8	#include <ev.h>	7	#include <ev.h>
9		8
10	/* what follows is a fully working example program */	9	=head1 EXAMPLE PROGRAM
		10
		11	#include <ev.h>
		12
11	ev_io stdin_watcher;	13	ev_io stdin_watcher;
12	ev_timer timeout_watcher;	14	ev_timer timeout_watcher;
13		15
14	/* called when data readable on stdin */	16	/* called when data readable on stdin */
15	static void	17	static void
…		…
61	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
62	watcher.	64	watcher.
63		65
64	=head1 FEATURES	66	=head1 FEATURES
65		67
66	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
67	kqueue mechanisms for file descriptor events, relative timers, absolute	69	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
68	timers with customised rescheduling, signal events, process status change	70	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
69	events (related to SIGCHLD), and event watchers dealing with the event	71	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
70	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
71	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
72	it to libevent for example).	81	for example).
73		82
74	=head1 CONVENTIONS	83	=head1 CONVENTIONS
75		84
76	Libev is very configurable. In this manual the default configuration	85	Libev is very configurable. In this manual the default configuration will
77	will be described, which supports multiple event loops. For more info	86	be described, which supports multiple event loops. For more info about
78	about various configuration options please have a look at the file	87	various configuration options please have a look at B<EMBED> section in
79	F<README.embed> in the libev distribution. If libev was configured without	88	this manual. If libev was configured without support for multiple event
80	support for multiple event loops, then all functions taking an initial	89	loops, then all functions taking an initial argument of name C<loop>
81	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.
82	will not have this argument.
83		91
84	=head1 TIME REPRESENTATION	92	=head1 TIME REPRESENTATION
85		93
86	Libev represents time as a single floating point number, representing the	94	Libev represents time as a single floating point number, representing the
87	(fractional) number of seconds since the (POSIX) epoch (somewhere near	95	(fractional) number of seconds since the (POSIX) epoch (somewhere near
…		…
116	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,
117	as this indicates an incompatible change. Minor versions are usually	125	as this indicates an incompatible change. Minor versions are usually
118	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
119	not a problem.	127	not a problem.
120		128
121	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
122	version:	130	version.
123		131
124	assert (("libev version mismatch",	132	assert (("libev version mismatch",
125	ev_version_major () == EV_VERSION_MAJOR	133	ev_version_major () == EV_VERSION_MAJOR
126	&& ev_version_minor () >= EV_VERSION_MINOR));	134	&& ev_version_minor () >= EV_VERSION_MINOR));
127		135
…		…
155	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	163	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
156	recommended ones.	164	recommended ones.
157		165
158	See the description of C<ev_embed> watchers for more info.	166	See the description of C<ev_embed> watchers for more info.
159		167
160	=item ev_set_allocator (void (cb)(void *ptr, size_t size))	168	=item ev_set_allocator (void (cb)(void *ptr, long size))
161		169
162	Sets the allocation function to use (the prototype and semantics are	170	Sets the allocation function to use (the prototype is similar - the
163	identical to the realloc C function). It is used to allocate and free	171	semantics is identical - to the realloc C function). It is used to
164	memory (no surprises here). If it returns zero when memory needs to be	172	allocate and free memory (no surprises here). If it returns zero when
165	allocated, the library might abort or take some potentially destructive	173	memory needs to be allocated, the library might abort or take some
166	action. The default is your system realloc function.	174	potentially destructive action. The default is your system realloc
		175	function.
167		176
168	You could override this function in high-availability programs to, say,	177	You could override this function in high-availability programs to, say,
169	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,
170	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.
171		180
172	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
173	retries: better than mine).	182	retries).
174		183
175	static void *	184	static void *
176	persistent_realloc (void *ptr, size_t size)	185	persistent_realloc (void *ptr, size_t size)
177	{	186	{
178	for (;;)	187	for (;;)
…		…
197	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
198	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
199	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
200	(such as abort).	209	(such as abort).
201		210
202	Example: do the same thing as libev does internally:	211	Example: This is basically the same thing that libev does internally, too.
203		212
204	static void	213	static void
205	fatal_error (const char *msg)	214	fatal_error (const char *msg)
206	{	215	{
207	perror (msg);	216	perror (msg);
…		…
257	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	266	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
258	override the flags completely if it is found in the environment. This is	267	override the flags completely if it is found in the environment. This is
259	useful to try out specific backends to test their performance, or to work	268	useful to try out specific backends to test their performance, or to work
260	around bugs.	269	around bugs.
261		270
		271	=item C<EVFLAG_FORKCHECK>
		272
		273	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		274	a fork, you can also make libev check for a fork in each iteration by
		275	enabling this flag.
		276
		277	This works by calling C<getpid ()> on every iteration of the loop,
		278	and thus this might slow down your event loop if you do a lot of loop
		279	iterations and little real work, but is usually not noticeable (on my
		280	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		281	without a syscall and thus I<very> fast, but my Linux system also has
		282	C<pthread_atfork> which is even faster).
		283
		284	The big advantage of this flag is that you can forget about fork (and
		285	forget about forgetting to tell libev about forking) when you use this
		286	flag.
		287
		288	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		289	environment variable.
		290
262	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	291	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
263		292
264	This is your standard select(2) backend. Not I<completely> standard, as	293	This is your standard select(2) backend. Not I<completely> standard, as
265	libev tries to roll its own fd_set with no limits on the number of fds,	294	libev tries to roll its own fd_set with no limits on the number of fds,
266	but if that fails, expect a fairly low limit on the number of fds when	295	but if that fails, expect a fairly low limit on the number of fds when
…		…
353	Similar to C<ev_default_loop>, but always creates a new event loop that is	382	Similar to C<ev_default_loop>, but always creates a new event loop that is
354	always distinct from the default loop. Unlike the default loop, it cannot	383	always distinct from the default loop. Unlike the default loop, it cannot
355	handle signal and child watchers, and attempts to do so will be greeted by	384	handle signal and child watchers, and attempts to do so will be greeted by
356	undefined behaviour (or a failed assertion if assertions are enabled).	385	undefined behaviour (or a failed assertion if assertions are enabled).
357		386
358	Example: try to create a event loop that uses epoll and nothing else.	387	Example: Try to create a event loop that uses epoll and nothing else.
359		388
360	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	389	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
361	if (!epoller)	390	if (!epoller)
362	fatal ("no epoll found here, maybe it hides under your chair");	391	fatal ("no epoll found here, maybe it hides under your chair");
363		392
…		…
400	=item ev_loop_fork (loop)	429	=item ev_loop_fork (loop)
401		430
402	Like C<ev_default_fork>, but acts on an event loop created by	431	Like C<ev_default_fork>, but acts on an event loop created by
403	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	432	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
404	after fork, and how you do this is entirely your own problem.	433	after fork, and how you do this is entirely your own problem.
		434
		435	=item unsigned int ev_loop_count (loop)
		436
		437	Returns the count of loop iterations for the loop, which is identical to
		438	the number of times libev did poll for new events. It starts at C<0> and
		439	happily wraps around with enough iterations.
		440
		441	This value can sometimes be useful as a generation counter of sorts (it
		442	"ticks" the number of loop iterations), as it roughly corresponds with
		443	C<ev_prepare> and C<ev_check> calls.
405		444
406	=item unsigned int ev_backend (loop)	445	=item unsigned int ev_backend (loop)
407		446
408	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	447	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
409	use.	448	use.
…		…
462	Signals and child watchers are implemented as I/O watchers, and will	501	Signals and child watchers are implemented as I/O watchers, and will
463	be handled here by queueing them when their watcher gets executed.	502	be handled here by queueing them when their watcher gets executed.
464	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	503	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
465	were used, return, otherwise continue with step *.	504	were used, return, otherwise continue with step *.
466		505
467	Example: queue some jobs and then loop until no events are outsanding	506	Example: Queue some jobs and then loop until no events are outsanding
468	anymore.	507	anymore.
469		508
470	... queue jobs here, make sure they register event watchers as long	509	... queue jobs here, make sure they register event watchers as long
471	... as they still have work to do (even an idle watcher will do..)	510	... as they still have work to do (even an idle watcher will do..)
472	ev_loop (my_loop, 0);	511	ev_loop (my_loop, 0);
…		…
492	visible to the libev user and should not keep C<ev_loop> from exiting if	531	visible to the libev user and should not keep C<ev_loop> from exiting if
493	no event watchers registered by it are active. It is also an excellent	532	no event watchers registered by it are active. It is also an excellent
494	way to do this for generic recurring timers or from within third-party	533	way to do this for generic recurring timers or from within third-party
495	libraries. Just remember to I<unref after start> and I<ref before stop>.	534	libraries. Just remember to I<unref after start> and I<ref before stop>.
496		535
497	Example: create a signal watcher, but keep it from keeping C<ev_loop>	536	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
498	running when nothing else is active.	537	running when nothing else is active.
499		538
500	struct dv_signal exitsig;	539	struct ev_signal exitsig;
501	ev_signal_init (&exitsig, sig_cb, SIGINT);	540	ev_signal_init (&exitsig, sig_cb, SIGINT);
502	ev_signal_start (myloop, &exitsig);	541	ev_signal_start (loop, &exitsig);
503	evf_unref (myloop);	542	evf_unref (loop);
504		543
505	Example: for some weird reason, unregister the above signal handler again.	544	Example: For some weird reason, unregister the above signal handler again.
506		545
507	ev_ref (myloop);	546	ev_ref (loop);
508	ev_signal_stop (myloop, &exitsig);	547	ev_signal_stop (loop, &exitsig);
509		548
510	=back	549	=back
511		550
512		551
513	=head1 ANATOMY OF A WATCHER	552	=head1 ANATOMY OF A WATCHER
…		…
696	events but its callback has not yet been invoked). As long as a watcher	735	events but its callback has not yet been invoked). As long as a watcher
697	is pending (but not active) you must not call an init function on it (but	736	is pending (but not active) you must not call an init function on it (but
698	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	737	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to
699	libev (e.g. you cnanot C<free ()> it).	738	libev (e.g. you cnanot C<free ()> it).
700		739
701	=item callback = ev_cb (ev_TYPE *watcher)	740	=item callback ev_cb (ev_TYPE *watcher)
702		741
703	Returns the callback currently set on the watcher.	742	Returns the callback currently set on the watcher.
704		743
705	=item ev_cb_set (ev_TYPE *watcher, callback)	744	=item ev_cb_set (ev_TYPE *watcher, callback)
706		745
707	Change the callback. You can change the callback at virtually any time	746	Change the callback. You can change the callback at virtually any time
708	(modulo threads).	747	(modulo threads).
		748
		749	=item ev_set_priority (ev_TYPE *watcher, priority)
		750
		751	=item int ev_priority (ev_TYPE *watcher)
		752
		753	Set and query the priority of the watcher. The priority is a small
		754	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		755	(default: C<-2>). Pending watchers with higher priority will be invoked
		756	before watchers with lower priority, but priority will not keep watchers
		757	from being executed (except for C<ev_idle> watchers).
		758
		759	This means that priorities are I<only> used for ordering callback
		760	invocation after new events have been received. This is useful, for
		761	example, to reduce latency after idling, or more often, to bind two
		762	watchers on the same event and make sure one is called first.
		763
		764	If you need to suppress invocation when higher priority events are pending
		765	you need to look at C<ev_idle> watchers, which provide this functionality.
		766
		767	The default priority used by watchers when no priority has been set is
		768	always C<0>, which is supposed to not be too high and not be too low :).
		769
		770	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		771	fine, as long as you do not mind that the priority value you query might
		772	or might not have been adjusted to be within valid range.
709		773
710	=back	774	=back
711		775
712		776
713	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	777	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
734	{	798	{
735	struct my_io w = (struct my_io )w_;	799	struct my_io w = (struct my_io )w_;
736	...	800	...
737	}	801	}
738		802
739	More interesting and less C-conformant ways of catsing your callback type	803	More interesting and less C-conformant ways of casting your callback type
740	have been omitted....	804	instead have been omitted.
		805
		806	Another common scenario is having some data structure with multiple
		807	watchers:
		808
		809	struct my_biggy
		810	{
		811	int some_data;
		812	ev_timer t1;
		813	ev_timer t2;
		814	}
		815
		816	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		817	you need to use C<offsetof>:
		818
		819	#include <stddef.h>
		820
		821	static void
		822	t1_cb (EV_P_ struct ev_timer *w, int revents)
		823	{
		824	struct my_biggy big = (struct my_biggy *
		825	(((char *)w) - offsetof (struct my_biggy, t1));
		826	}
		827
		828	static void
		829	t2_cb (EV_P_ struct ev_timer *w, int revents)
		830	{
		831	struct my_biggy big = (struct my_biggy *
		832	(((char *)w) - offsetof (struct my_biggy, t2));
		833	}
741		834
742		835
743	=head1 WATCHER TYPES	836	=head1 WATCHER TYPES
744		837
745	This section describes each watcher in detail, but will not repeat	838	This section describes each watcher in detail, but will not repeat
…		…
814		907
815	The events being watched.	908	The events being watched.
816		909
817	=back	910	=back
818		911
819	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	912	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
820	readable, but only once. Since it is likely line-buffered, you could	913	readable, but only once. Since it is likely line-buffered, you could
821	attempt to read a whole line in the callback:	914	attempt to read a whole line in the callback.
822		915
823	static void	916	static void
824	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	917	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
825	{	918	{
826	ev_io_stop (loop, w);	919	ev_io_stop (loop, w);
…		…
878	=item ev_timer_again (loop)	971	=item ev_timer_again (loop)
879		972
880	This will act as if the timer timed out and restart it again if it is	973	This will act as if the timer timed out and restart it again if it is
881	repeating. The exact semantics are:	974	repeating. The exact semantics are:
882		975
		976	If the timer is pending, its pending status is cleared.
		977
883	If the timer is started but nonrepeating, stop it.	978	If the timer is started but nonrepeating, stop it (as if it timed out).
884		979
885	If the timer is repeating, either start it if necessary (with the repeat	980	If the timer is repeating, either start it if necessary (with the
886	value), or reset the running timer to the repeat value.	981	C<repeat> value), or reset the running timer to the C<repeat> value.
887		982
888	This sounds a bit complicated, but here is a useful and typical	983	This sounds a bit complicated, but here is a useful and typical
889	example: Imagine you have a tcp connection and you want a so-called	984	example: Imagine you have a tcp connection and you want a so-called idle
890	idle timeout, that is, you want to be called when there have been,	985	timeout, that is, you want to be called when there have been, say, 60
891	say, 60 seconds of inactivity on the socket. The easiest way to do	986	seconds of inactivity on the socket. The easiest way to do this is to
892	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling	987	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
893	C<ev_timer_again> each time you successfully read or write some data. If	988	C<ev_timer_again> each time you successfully read or write some data. If
894	you go into an idle state where you do not expect data to travel on the	989	you go into an idle state where you do not expect data to travel on the
895	socket, you can stop the timer, and again will automatically restart it if	990	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
896	need be.	991	automatically restart it if need be.
897		992
898	You can also ignore the C<after> value and C<ev_timer_start> altogether	993	That means you can ignore the C<after> value and C<ev_timer_start>
899	and only ever use the C<repeat> value:	994	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
900		995
901	ev_timer_init (timer, callback, 0., 5.);	996	ev_timer_init (timer, callback, 0., 5.);
902	ev_timer_again (loop, timer);	997	ev_timer_again (loop, timer);
903	...	998	...
904	timer->again = 17.;	999	timer->again = 17.;
905	ev_timer_again (loop, timer);	1000	ev_timer_again (loop, timer);
906	...	1001	...
907	timer->again = 10.;	1002	timer->again = 10.;
908	ev_timer_again (loop, timer);	1003	ev_timer_again (loop, timer);
909		1004
910	This is more efficient then stopping/starting the timer eahc time you want	1005	This is more slightly efficient then stopping/starting the timer each time
911	to modify its timeout value.	1006	you want to modify its timeout value.
912		1007
913	=item ev_tstamp repeat [read-write]	1008	=item ev_tstamp repeat [read-write]
914		1009
915	The current C<repeat> value. Will be used each time the watcher times out	1010	The current C<repeat> value. Will be used each time the watcher times out
916	or C<ev_timer_again> is called and determines the next timeout (if any),	1011	or C<ev_timer_again> is called and determines the next timeout (if any),
917	which is also when any modifications are taken into account.	1012	which is also when any modifications are taken into account.
918		1013
919	=back	1014	=back
920		1015
921	Example: create a timer that fires after 60 seconds.	1016	Example: Create a timer that fires after 60 seconds.
922		1017
923	static void	1018	static void
924	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	1019	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
925	{	1020	{
926	.. one minute over, w is actually stopped right here	1021	.. one minute over, w is actually stopped right here
…		…
928		1023
929	struct ev_timer mytimer;	1024	struct ev_timer mytimer;
930	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1025	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
931	ev_timer_start (loop, &mytimer);	1026	ev_timer_start (loop, &mytimer);
932		1027
933	Example: create a timeout timer that times out after 10 seconds of	1028	Example: Create a timeout timer that times out after 10 seconds of
934	inactivity.	1029	inactivity.
935		1030
936	static void	1031	static void
937	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1032	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
938	{	1033	{
…		…
1063	switched off. Can be changed any time, but changes only take effect when	1158	switched off. Can be changed any time, but changes only take effect when
1064	the periodic timer fires or C<ev_periodic_again> is being called.	1159	the periodic timer fires or C<ev_periodic_again> is being called.
1065		1160
1066	=back	1161	=back
1067		1162
1068	Example: call a callback every hour, or, more precisely, whenever the	1163	Example: Call a callback every hour, or, more precisely, whenever the
1069	system clock is divisible by 3600. The callback invocation times have	1164	system clock is divisible by 3600. The callback invocation times have
1070	potentially a lot of jittering, but good long-term stability.	1165	potentially a lot of jittering, but good long-term stability.
1071		1166
1072	static void	1167	static void
1073	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1168	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
1077		1172
1078	struct ev_periodic hourly_tick;	1173	struct ev_periodic hourly_tick;
1079	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1174	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1080	ev_periodic_start (loop, &hourly_tick);	1175	ev_periodic_start (loop, &hourly_tick);
1081		1176
1082	Example: the same as above, but use a reschedule callback to do it:	1177	Example: The same as above, but use a reschedule callback to do it:
1083		1178
1084	#include <math.h>	1179	#include <math.h>
1085		1180
1086	static ev_tstamp	1181	static ev_tstamp
1087	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1182	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
1089	return fmod (now, 3600.) + 3600.;	1184	return fmod (now, 3600.) + 3600.;
1090	}	1185	}
1091		1186
1092	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1187	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1093		1188
1094	Example: call a callback every hour, starting now:	1189	Example: Call a callback every hour, starting now:
1095		1190
1096	struct ev_periodic hourly_tick;	1191	struct ev_periodic hourly_tick;
1097	ev_periodic_init (&hourly_tick, clock_cb,	1192	ev_periodic_init (&hourly_tick, clock_cb,
1098	fmod (ev_now (loop), 3600.), 3600., 0);	1193	fmod (ev_now (loop), 3600.), 3600., 0);
1099	ev_periodic_start (loop, &hourly_tick);	1194	ev_periodic_start (loop, &hourly_tick);
…		…
1160	The process exit/trace status caused by C<rpid> (see your systems	1255	The process exit/trace status caused by C<rpid> (see your systems
1161	C<waitpid> and C<sys/wait.h> documentation for details).	1256	C<waitpid> and C<sys/wait.h> documentation for details).
1162		1257
1163	=back	1258	=back
1164		1259
1165	Example: try to exit cleanly on SIGINT and SIGTERM.	1260	Example: Try to exit cleanly on SIGINT and SIGTERM.
1166		1261
1167	static void	1262	static void
1168	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1263	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1169	{	1264	{
1170	ev_unloop (loop, EVUNLOOP_ALL);	1265	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1185	not exist" is a status change like any other. The condition "path does	1280	not exist" is a status change like any other. The condition "path does
1186	not exist" is signified by the C<st_nlink> field being zero (which is	1281	not exist" is signified by the C<st_nlink> field being zero (which is
1187	otherwise always forced to be at least one) and all the other fields of	1282	otherwise always forced to be at least one) and all the other fields of
1188	the stat buffer having unspecified contents.	1283	the stat buffer having unspecified contents.
1189		1284
		1285	The path I<should> be absolute and I<must not> end in a slash. If it is
		1286	relative and your working directory changes, the behaviour is undefined.
		1287
1190	Since there is no standard to do this, the portable implementation simply	1288	Since there is no standard to do this, the portable implementation simply
1191	calls C<stat (2)> regulalry on the path to see if it changed somehow. You	1289	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1192	can specify a recommended polling interval for this case. If you specify	1290	can specify a recommended polling interval for this case. If you specify
1193	a polling interval of C<0> (highly recommended!) then a I<suitable,	1291	a polling interval of C<0> (highly recommended!) then a I<suitable,
1194	unspecified default> value will be used (which you can expect to be around	1292	unspecified default> value will be used (which you can expect to be around
1195	five seconds, although this might change dynamically). Libev will also	1293	five seconds, although this might change dynamically). Libev will also
1196	impose a minimum interval which is currently around C<0.1>, but thats	1294	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1198		1296
1199	This watcher type is not meant for massive numbers of stat watchers,	1297	This watcher type is not meant for massive numbers of stat watchers,
1200	as even with OS-supported change notifications, this can be	1298	as even with OS-supported change notifications, this can be
1201	resource-intensive.	1299	resource-intensive.
1202		1300
1203	At the time of this writing, no specific OS backends are implemented, but	1301	At the time of this writing, only the Linux inotify interface is
1204	if demand increases, at least a kqueue and inotify backend will be added.	1302	implemented (implementing kqueue support is left as an exercise for the
		1303	reader). Inotify will be used to give hints only and should not change the
		1304	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1305	to fall back to regular polling again even with inotify, but changes are
		1306	usually detected immediately, and if the file exists there will be no
		1307	polling.
1205		1308
1206	=over 4	1309	=over 4
1207		1310
1208	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1311	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1209		1312
…		…
1273	ev_stat_start (loop, &passwd);	1376	ev_stat_start (loop, &passwd);
1274		1377
1275		1378
1276	=head2 C<ev_idle> - when you've got nothing better to do...	1379	=head2 C<ev_idle> - when you've got nothing better to do...
1277		1380
1278	Idle watchers trigger events when there are no other events are pending	1381	Idle watchers trigger events when no other events of the same or higher
1279	(prepare, check and other idle watchers do not count). That is, as long	1382	priority are pending (prepare, check and other idle watchers do not
1280	as your process is busy handling sockets or timeouts (or even signals,	1383	count).
1281	imagine) it will not be triggered. But when your process is idle all idle	1384
1282	watchers are being called again and again, once per event loop iteration -	1385	That is, as long as your process is busy handling sockets or timeouts
		1386	(or even signals, imagine) of the same or higher priority it will not be
		1387	triggered. But when your process is idle (or only lower-priority watchers
		1388	are pending), the idle watchers are being called once per event loop
1283	until stopped, that is, or your process receives more events and becomes	1389	iteration - until stopped, that is, or your process receives more events
1284	busy.	1390	and becomes busy again with higher priority stuff.
1285		1391
1286	The most noteworthy effect is that as long as any idle watchers are	1392	The most noteworthy effect is that as long as any idle watchers are
1287	active, the process will not block when waiting for new events.	1393	active, the process will not block when waiting for new events.
1288		1394
1289	Apart from keeping your process non-blocking (which is a useful	1395	Apart from keeping your process non-blocking (which is a useful
…		…
1299	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1405	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1300	believe me.	1406	believe me.
1301		1407
1302	=back	1408	=back
1303		1409
1304	Example: dynamically allocate an C<ev_idle>, start it, and in the	1410	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1305	callback, free it. Alos, use no error checking, as usual.	1411	callback, free it. Also, use no error checking, as usual.
1306		1412
1307	static void	1413	static void
1308	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1414	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1309	{	1415	{
1310	free (w);	1416	free (w);
…		…
1389		1495
1390	// create io watchers for each fd and a timer before blocking	1496	// create io watchers for each fd and a timer before blocking
1391	static void	1497	static void
1392	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1498	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1393	{	1499	{
1394	int timeout = 3600000;truct pollfd fds [nfd];	1500	int timeout = 3600000;
		1501	struct pollfd fds [nfd];
1395	// actual code will need to loop here and realloc etc.	1502	// actual code will need to loop here and realloc etc.
1396	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1503	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1397		1504
1398	/* the callback is illegal, but won't be called as we stop during check */	1505	/* the callback is illegal, but won't be called as we stop during check */
1399	ev_timer_init (&tw, 0, timeout * 1e-3);	1506	ev_timer_init (&tw, 0, timeout * 1e-3);
…		…
1780	Similar to the other two macros, this gives you the value of the default	1887	Similar to the other two macros, this gives you the value of the default
1781	loop, if multiple loops are supported ("ev loop default").	1888	loop, if multiple loops are supported ("ev loop default").
1782		1889
1783	=back	1890	=back
1784		1891
1785	Example: Declare and initialise a check watcher, working regardless of	1892	Example: Declare and initialise a check watcher, utilising the above
1786	wether multiple loops are supported or not.	1893	macros so it will work regardless of wether multiple loops are supported
		1894	or not.
1787		1895
1788	static void	1896	static void
1789	check_cb (EV_P_ ev_timer *w, int revents)	1897	check_cb (EV_P_ ev_timer *w, int revents)
1790	{	1898	{
1791	ev_check_stop (EV_A_ w);	1899	ev_check_stop (EV_A_ w);
…		…
1793		1901
1794	ev_check check;	1902	ev_check check;
1795	ev_check_init (&check, check_cb);	1903	ev_check_init (&check, check_cb);
1796	ev_check_start (EV_DEFAULT_ &check);	1904	ev_check_start (EV_DEFAULT_ &check);
1797	ev_loop (EV_DEFAULT_ 0);	1905	ev_loop (EV_DEFAULT_ 0);
1798
1799		1906
1800	=head1 EMBEDDING	1907	=head1 EMBEDDING
1801		1908
1802	Libev can (and often is) directly embedded into host	1909	Libev can (and often is) directly embedded into host
1803	applications. Examples of applications that embed it include the Deliantra	1910	applications. Examples of applications that embed it include the Deliantra
…		…
1843	ev_vars.h	1950	ev_vars.h
1844	ev_wrap.h	1951	ev_wrap.h
1845		1952
1846	ev_win32.c required on win32 platforms only	1953	ev_win32.c required on win32 platforms only
1847		1954
1848	ev_select.c only when select backend is enabled (which is by default)	1955	ev_select.c only when select backend is enabled (which is enabled by default)
1849	ev_poll.c only when poll backend is enabled (disabled by default)	1956	ev_poll.c only when poll backend is enabled (disabled by default)
1850	ev_epoll.c only when the epoll backend is enabled (disabled by default)	1957	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1851	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	1958	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1852	ev_port.c only when the solaris port backend is enabled (disabled by default)	1959	ev_port.c only when the solaris port backend is enabled (disabled by default)
1853		1960
…		…
1978		2085
1979	=item EV_USE_DEVPOLL	2086	=item EV_USE_DEVPOLL
1980		2087
1981	reserved for future expansion, works like the USE symbols above.	2088	reserved for future expansion, works like the USE symbols above.
1982		2089
		2090	=item EV_USE_INOTIFY
		2091
		2092	If defined to be C<1>, libev will compile in support for the Linux inotify
		2093	interface to speed up C<ev_stat> watchers. Its actual availability will
		2094	be detected at runtime.
		2095
1983	=item EV_H	2096	=item EV_H
1984		2097
1985	The name of the F<ev.h> header file used to include it. The default if	2098	The name of the F<ev.h> header file used to include it. The default if
1986	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2099	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
1987	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2100	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
2016		2129
2017	If undefined or defined to be C<1>, then periodic timers are supported. If	2130	If undefined or defined to be C<1>, then periodic timers are supported. If
2018	defined to be C<0>, then they are not. Disabling them saves a few kB of	2131	defined to be C<0>, then they are not. Disabling them saves a few kB of
2019	code.	2132	code.
2020		2133
		2134	=item EV_IDLE_ENABLE
		2135
		2136	If undefined or defined to be C<1>, then idle watchers are supported. If
		2137	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2138	code.
		2139
2021	=item EV_EMBED_ENABLE	2140	=item EV_EMBED_ENABLE
2022		2141
2023	If undefined or defined to be C<1>, then embed watchers are supported. If	2142	If undefined or defined to be C<1>, then embed watchers are supported. If
2024	defined to be C<0>, then they are not.	2143	defined to be C<0>, then they are not.
2025		2144
…		…
2042	=item EV_PID_HASHSIZE	2161	=item EV_PID_HASHSIZE
2043		2162
2044	C<ev_child> watchers use a small hash table to distribute workload by	2163	C<ev_child> watchers use a small hash table to distribute workload by
2045	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	2164	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
2046	than enough. If you need to manage thousands of children you might want to	2165	than enough. If you need to manage thousands of children you might want to
2047	increase this value.	2166	increase this value (I<must> be a power of two).
		2167
		2168	=item EV_INOTIFY_HASHSIZE
		2169
		2170	C<ev_staz> watchers use a small hash table to distribute workload by
		2171	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2172	usually more than enough. If you need to manage thousands of C<ev_stat>
		2173	watchers you might want to increase this value (I<must> be a power of
		2174	two).
2048		2175
2049	=item EV_COMMON	2176	=item EV_COMMON
2050		2177
2051	By default, all watchers have a C<void *data> member. By redefining	2178	By default, all watchers have a C<void *data> member. By redefining
2052	this macro to a something else you can include more and other types of	2179	this macro to a something else you can include more and other types of
…		…
2081	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2208	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2082	will be compiled. It is pretty complex because it provides its own header	2209	will be compiled. It is pretty complex because it provides its own header
2083	file.	2210	file.
2084		2211
2085	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2212	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2086	that everybody includes and which overrides some autoconf choices:	2213	that everybody includes and which overrides some configure choices:
2087		2214
		2215	#define EV_MINIMAL 1
2088	#define EV_USE_POLL 0	2216	#define EV_USE_POLL 0
2089	#define EV_MULTIPLICITY 0	2217	#define EV_MULTIPLICITY 0
2090	#define EV_PERIODICS 0	2218	#define EV_PERIODIC_ENABLE 0
		2219	#define EV_STAT_ENABLE 0
		2220	#define EV_FORK_ENABLE 0
2091	#define EV_CONFIG_H <config.h>	2221	#define EV_CONFIG_H <config.h>
		2222	#define EV_MINPRI 0
		2223	#define EV_MAXPRI 0
2092		2224
2093	#include "ev++.h"	2225	#include "ev++.h"
2094		2226
2095	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2227	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2096		2228
…		…
2112		2244
2113	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2245	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2114		2246
2115	=item Stopping check/prepare/idle watchers: O(1)	2247	=item Stopping check/prepare/idle watchers: O(1)
2116		2248
2117	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2249	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2118		2250
2119	=item Finding the next timer per loop iteration: O(1)	2251	=item Finding the next timer per loop iteration: O(1)
2120		2252
2121	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2253	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2122		2254

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Comparing libev/ev.pod (file contents): Revision 1.53 by root, Tue Nov 27 20:15:02 2007 UTC vs. Revision 1.67 by root, Fri Dec 7 16:44:12 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.53 by root, Tue Nov 27 20:15:02 2007 UTC vs.
Revision 1.67 by root, Fri Dec 7 16:44:12 2007 UTC