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

Comparing libev/ev.pod (file contents):
Revision 1.48 by root, Tue Nov 27 08:11:52 2007 UTC vs.
Revision 1.68 by root, Fri Dec 7 18:09:43 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);
…		…
218	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	266	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
219	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
220	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
221	around bugs.	269	around bugs.
222		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
223	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	291	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
224		292
225	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
226	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,
227	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
…		…
314	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
315	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
316	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
317	undefined behaviour (or a failed assertion if assertions are enabled).	385	undefined behaviour (or a failed assertion if assertions are enabled).
318		386
319	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.
320		388
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	389	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
322	if (!epoller)	390	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	391	fatal ("no epoll found here, maybe it hides under your chair");
324		392
…		…
361	=item ev_loop_fork (loop)	429	=item ev_loop_fork (loop)
362		430
363	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
364	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
365	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.
366		444
367	=item unsigned int ev_backend (loop)	445	=item unsigned int ev_backend (loop)
368		446
369	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
370	use.	448	use.
…		…
423	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
424	be handled here by queueing them when their watcher gets executed.	502	be handled here by queueing them when their watcher gets executed.
425	- 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
426	were used, return, otherwise continue with step *.	504	were used, return, otherwise continue with step *.
427		505
428	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
429	anymore.	507	anymore.
430		508
431	... queue jobs here, make sure they register event watchers as long	509	... 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..)	510	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	511	ev_loop (my_loop, 0);
…		…
453	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
454	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
455	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
456	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>.
457		535
458	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>
459	running when nothing else is active.	537	running when nothing else is active.
460		538
461	struct dv_signal exitsig;	539	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	540	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	541	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	542	evf_unref (loop);
465		543
466	Example: for some weird reason, unregister the above signal handler again.	544	Example: For some weird reason, unregister the above signal handler again.
467		545
468	ev_ref (myloop);	546	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	547	ev_signal_stop (loop, &exitsig);
470		548
471	=back	549	=back
472		550
473		551
474	=head1 ANATOMY OF A WATCHER	552	=head1 ANATOMY OF A WATCHER
…		…
565	received events. Callbacks of both watcher types can start and stop as	643	received events. Callbacks of both watcher types can start and stop as
566	many watchers as they want, and all of them will be taken into account	644	many watchers as they want, and all of them will be taken into account
567	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	645	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
568	C<ev_loop> from blocking).	646	C<ev_loop> from blocking).
569		647
		648	=item C<EV_EMBED>
		649
		650	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		651
		652	=item C<EV_FORK>
		653
		654	The event loop has been resumed in the child process after fork (see
		655	C<ev_fork>).
		656
570	=item C<EV_ERROR>	657	=item C<EV_ERROR>
571		658
572	An unspecified error has occured, the watcher has been stopped. This might	659	An unspecified error has occured, the watcher has been stopped. This might
573	happen because the watcher could not be properly started because libev	660	happen because the watcher could not be properly started because libev
574	ran out of memory, a file descriptor was found to be closed or any other	661	ran out of memory, a file descriptor was found to be closed or any other
…		…
648	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
649	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
650	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
651	libev (e.g. you cnanot C<free ()> it).	738	libev (e.g. you cnanot C<free ()> it).
652		739
653	=item callback = ev_cb (ev_TYPE *watcher)	740	=item callback ev_cb (ev_TYPE *watcher)
654		741
655	Returns the callback currently set on the watcher.	742	Returns the callback currently set on the watcher.
656		743
657	=item ev_cb_set (ev_TYPE *watcher, callback)	744	=item ev_cb_set (ev_TYPE *watcher, callback)
658		745
659	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
660	(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.
661		773
662	=back	774	=back
663		775
664		776
665	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	777	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
686	{	798	{
687	struct my_io w = (struct my_io )w_;	799	struct my_io w = (struct my_io )w_;
688	...	800	...
689	}	801	}
690		802
691	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
692	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	}
693		834
694		835
695	=head1 WATCHER TYPES	836	=head1 WATCHER TYPES
696		837
697	This section describes each watcher in detail, but will not repeat	838	This section describes each watcher in detail, but will not repeat
…		…
742	it is best to always use non-blocking I/O: An extra C<read>(2) returning	883	it is best to always use non-blocking I/O: An extra C<read>(2) returning
743	C<EAGAIN> is far preferable to a program hanging until some data arrives.	884	C<EAGAIN> is far preferable to a program hanging until some data arrives.
744		885
745	If you cannot run the fd in non-blocking mode (for example you should not	886	If you cannot run the fd in non-blocking mode (for example you should not
746	play around with an Xlib connection), then you have to seperately re-test	887	play around with an Xlib connection), then you have to seperately re-test
747	wether a file descriptor is really ready with a known-to-be good interface	888	whether a file descriptor is really ready with a known-to-be good interface
748	such as poll (fortunately in our Xlib example, Xlib already does this on	889	such as poll (fortunately in our Xlib example, Xlib already does this on
749	its own, so its quite safe to use).	890	its own, so its quite safe to use).
750		891
751	=over 4	892	=over 4
752		893
…		…
766		907
767	The events being watched.	908	The events being watched.
768		909
769	=back	910	=back
770		911
771	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
772	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
773	attempt to read a whole line in the callback:	914	attempt to read a whole line in the callback.
774		915
775	static void	916	static void
776	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)
777	{	918	{
778	ev_io_stop (loop, w);	919	ev_io_stop (loop, w);
…		…
830	=item ev_timer_again (loop)	971	=item ev_timer_again (loop)
831		972
832	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
833	repeating. The exact semantics are:	974	repeating. The exact semantics are:
834		975
		976	If the timer is pending, its pending status is cleared.
		977
835	If the timer is started but nonrepeating, stop it.	978	If the timer is started but nonrepeating, stop it (as if it timed out).
836		979
837	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
838	value), or reset the running timer to the repeat value.	981	C<repeat> value), or reset the running timer to the C<repeat> value.
839		982
840	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
841	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
842	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
843	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
844	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
845	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
846	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
847	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
848	need be.	991	automatically restart it if need be.
849		992
850	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>
851	and only ever use the C<repeat> value:	994	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
852		995
853	ev_timer_init (timer, callback, 0., 5.);	996	ev_timer_init (timer, callback, 0., 5.);
854	ev_timer_again (loop, timer);	997	ev_timer_again (loop, timer);
855	...	998	...
856	timer->again = 17.;	999	timer->again = 17.;
857	ev_timer_again (loop, timer);	1000	ev_timer_again (loop, timer);
858	...	1001	...
859	timer->again = 10.;	1002	timer->again = 10.;
860	ev_timer_again (loop, timer);	1003	ev_timer_again (loop, timer);
861		1004
862	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
863	to modify its timeout value.	1006	you want to modify its timeout value.
864		1007
865	=item ev_tstamp repeat [read-write]	1008	=item ev_tstamp repeat [read-write]
866		1009
867	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
868	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),
869	which is also when any modifications are taken into account.	1012	which is also when any modifications are taken into account.
870		1013
871	=back	1014	=back
872		1015
873	Example: create a timer that fires after 60 seconds.	1016	Example: Create a timer that fires after 60 seconds.
874		1017
875	static void	1018	static void
876	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)
877	{	1020	{
878	.. one minute over, w is actually stopped right here	1021	.. one minute over, w is actually stopped right here
…		…
880		1023
881	struct ev_timer mytimer;	1024	struct ev_timer mytimer;
882	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1025	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
883	ev_timer_start (loop, &mytimer);	1026	ev_timer_start (loop, &mytimer);
884		1027
885	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
886	inactivity.	1029	inactivity.
887		1030
888	static void	1031	static void
889	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)
890	{	1033	{
…		…
1015	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
1016	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.
1017		1160
1018	=back	1161	=back
1019		1162
1020	Example: call a callback every hour, or, more precisely, whenever the	1163	Example: Call a callback every hour, or, more precisely, whenever the
1021	system clock is divisible by 3600. The callback invocation times have	1164	system clock is divisible by 3600. The callback invocation times have
1022	potentially a lot of jittering, but good long-term stability.	1165	potentially a lot of jittering, but good long-term stability.
1023		1166
1024	static void	1167	static void
1025	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)
…		…
1029		1172
1030	struct ev_periodic hourly_tick;	1173	struct ev_periodic hourly_tick;
1031	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1174	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1032	ev_periodic_start (loop, &hourly_tick);	1175	ev_periodic_start (loop, &hourly_tick);
1033		1176
1034	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:
1035		1178
1036	#include <math.h>	1179	#include <math.h>
1037		1180
1038	static ev_tstamp	1181	static ev_tstamp
1039	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1182	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
1041	return fmod (now, 3600.) + 3600.;	1184	return fmod (now, 3600.) + 3600.;
1042	}	1185	}
1043		1186
1044	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);
1045		1188
1046	Example: call a callback every hour, starting now:	1189	Example: Call a callback every hour, starting now:
1047		1190
1048	struct ev_periodic hourly_tick;	1191	struct ev_periodic hourly_tick;
1049	ev_periodic_init (&hourly_tick, clock_cb,	1192	ev_periodic_init (&hourly_tick, clock_cb,
1050	fmod (ev_now (loop), 3600.), 3600., 0);	1193	fmod (ev_now (loop), 3600.), 3600., 0);
1051	ev_periodic_start (loop, &hourly_tick);	1194	ev_periodic_start (loop, &hourly_tick);
…		…
1112	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
1113	C<waitpid> and C<sys/wait.h> documentation for details).	1256	C<waitpid> and C<sys/wait.h> documentation for details).
1114		1257
1115	=back	1258	=back
1116		1259
1117	Example: try to exit cleanly on SIGINT and SIGTERM.	1260	Example: Try to exit cleanly on SIGINT and SIGTERM.
1118		1261
1119	static void	1262	static void
1120	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)
1121	{	1264	{
1122	ev_unloop (loop, EVUNLOOP_ALL);	1265	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1137	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
1138	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
1139	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
1140	the stat buffer having unspecified contents.	1283	the stat buffer having unspecified contents.
1141		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
1142	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
1143	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
1144	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
1145	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,
1146	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
1147	five seconds, although this might change dynamically). Libev will also	1293	five seconds, although this might change dynamically). Libev will also
1148	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
…		…
1150		1296
1151	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,
1152	as even with OS-supported change notifications, this can be	1298	as even with OS-supported change notifications, this can be
1153	resource-intensive.	1299	resource-intensive.
1154		1300
1155	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
1156	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.
1157		1308
1158	=over 4	1309	=over 4
1159		1310
1160	=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)
1161		1312
…		…
1225	ev_stat_start (loop, &passwd);	1376	ev_stat_start (loop, &passwd);
1226		1377
1227		1378
1228	=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...
1229		1380
1230	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
1231	(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
1232	as your process is busy handling sockets or timeouts (or even signals,	1383	count).
1233	imagine) it will not be triggered. But when your process is idle all idle	1384
1234	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
1235	until stopped, that is, or your process receives more events and becomes	1389	iteration - until stopped, that is, or your process receives more events
1236	busy.	1390	and becomes busy again with higher priority stuff.
1237		1391
1238	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
1239	active, the process will not block when waiting for new events.	1393	active, the process will not block when waiting for new events.
1240		1394
1241	Apart from keeping your process non-blocking (which is a useful	1395	Apart from keeping your process non-blocking (which is a useful
…		…
1251	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,
1252	believe me.	1406	believe me.
1253		1407
1254	=back	1408	=back
1255		1409
1256	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
1257	callback, free it. Alos, use no error checking, as usual.	1411	callback, free it. Also, use no error checking, as usual.
1258		1412
1259	static void	1413	static void
1260	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)
1261	{	1415	{
1262	free (w);	1416	free (w);
…		…
1341		1495
1342	// create io watchers for each fd and a timer before blocking	1496	// create io watchers for each fd and a timer before blocking
1343	static void	1497	static void
1344	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1498	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1345	{	1499	{
1346	int timeout = 3600000;truct pollfd fds [nfd];	1500	int timeout = 3600000;
		1501	struct pollfd fds [nfd];
1347	// actual code will need to loop here and realloc etc.	1502	// actual code will need to loop here and realloc etc.
1348	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1503	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1349		1504
1350	/* 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 */
1351	ev_timer_init (&tw, 0, timeout * 1e-3);	1506	ev_timer_init (&tw, 0, timeout * 1e-3);
…		…
1470	The embedded event loop.	1625	The embedded event loop.
1471		1626
1472	=back	1627	=back
1473		1628
1474		1629
		1630	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1631
		1632	Fork watchers are called when a C<fork ()> was detected (usually because
		1633	whoever is a good citizen cared to tell libev about it by calling
		1634	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1635	event loop blocks next and before C<ev_check> watchers are being called,
		1636	and only in the child after the fork. If whoever good citizen calling
		1637	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1638	handlers will be invoked, too, of course.
		1639
		1640	=over 4
		1641
		1642	=item ev_fork_init (ev_signal *, callback)
		1643
		1644	Initialises and configures the fork watcher - it has no parameters of any
		1645	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1646	believe me.
		1647
		1648	=back
		1649
		1650
1475	=head1 OTHER FUNCTIONS	1651	=head1 OTHER FUNCTIONS
1476		1652
1477	There are some other functions of possible interest. Described. Here. Now.	1653	There are some other functions of possible interest. Described. Here. Now.
1478		1654
1479	=over 4	1655	=over 4
…		…
1638		1814
1639	=item w->sweep () C<ev::embed> only	1815	=item w->sweep () C<ev::embed> only
1640		1816
1641	Invokes C<ev_embed_sweep>.	1817	Invokes C<ev_embed_sweep>.
1642		1818
		1819	=item w->update () C<ev::stat> only
		1820
		1821	Invokes C<ev_stat_stat>.
		1822
1643	=back	1823	=back
1644		1824
1645	=back	1825	=back
1646		1826
1647	Example: Define a class with an IO and idle watcher, start one of them in	1827	Example: Define a class with an IO and idle watcher, start one of them in
…		…
1659	: io (this, &myclass::io_cb),	1839	: io (this, &myclass::io_cb),
1660	idle (this, &myclass::idle_cb)	1840	idle (this, &myclass::idle_cb)
1661	{	1841	{
1662	io.start (fd, ev::READ);	1842	io.start (fd, ev::READ);
1663	}	1843	}
		1844
		1845
		1846	=head1 MACRO MAGIC
		1847
		1848	Libev can be compiled with a variety of options, the most fundemantal is
		1849	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
		1850	callbacks have an initial C<struct ev_loop *> argument.
		1851
		1852	To make it easier to write programs that cope with either variant, the
		1853	following macros are defined:
		1854
		1855	=over 4
		1856
		1857	=item C<EV_A>, C<EV_A_>
		1858
		1859	This provides the loop I<argument> for functions, if one is required ("ev
		1860	loop argument"). The C<EV_A> form is used when this is the sole argument,
		1861	C<EV_A_> is used when other arguments are following. Example:
		1862
		1863	ev_unref (EV_A);
		1864	ev_timer_add (EV_A_ watcher);
		1865	ev_loop (EV_A_ 0);
		1866
		1867	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		1868	which is often provided by the following macro.
		1869
		1870	=item C<EV_P>, C<EV_P_>
		1871
		1872	This provides the loop I<parameter> for functions, if one is required ("ev
		1873	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		1874	C<EV_P_> is used when other parameters are following. Example:
		1875
		1876	// this is how ev_unref is being declared
		1877	static void ev_unref (EV_P);
		1878
		1879	// this is how you can declare your typical callback
		1880	static void cb (EV_P_ ev_timer *w, int revents)
		1881
		1882	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		1883	suitable for use with C<EV_A>.
		1884
		1885	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		1886
		1887	Similar to the other two macros, this gives you the value of the default
		1888	loop, if multiple loops are supported ("ev loop default").
		1889
		1890	=back
		1891
		1892	Example: Declare and initialise a check watcher, utilising the above
		1893	macros so it will work regardless of whether multiple loops are supported
		1894	or not.
		1895
		1896	static void
		1897	check_cb (EV_P_ ev_timer *w, int revents)
		1898	{
		1899	ev_check_stop (EV_A_ w);
		1900	}
		1901
		1902	ev_check check;
		1903	ev_check_init (&check, check_cb);
		1904	ev_check_start (EV_DEFAULT_ &check);
		1905	ev_loop (EV_DEFAULT_ 0);
1664		1906
1665	=head1 EMBEDDING	1907	=head1 EMBEDDING
1666		1908
1667	Libev can (and often is) directly embedded into host	1909	Libev can (and often is) directly embedded into host
1668	applications. Examples of applications that embed it include the Deliantra	1910	applications. Examples of applications that embed it include the Deliantra
…		…
1708	ev_vars.h	1950	ev_vars.h
1709	ev_wrap.h	1951	ev_wrap.h
1710		1952
1711	ev_win32.c required on win32 platforms only	1953	ev_win32.c required on win32 platforms only
1712		1954
1713	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)
1714	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)
1715	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)
1716	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)
1717	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)
1718		1960
…		…
1843		2085
1844	=item EV_USE_DEVPOLL	2086	=item EV_USE_DEVPOLL
1845		2087
1846	reserved for future expansion, works like the USE symbols above.	2088	reserved for future expansion, works like the USE symbols above.
1847		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
1848	=item EV_H	2096	=item EV_H
1849		2097
1850	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
1851	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
1852	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.
…		…
1881		2129
1882	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
1883	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
1884	code.	2132	code.
1885		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
1886	=item EV_EMBED_ENABLE	2140	=item EV_EMBED_ENABLE
1887		2141
1888	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
1889	defined to be C<0>, then they are not.	2143	defined to be C<0>, then they are not.
1890		2144
1891	=item EV_STAT_ENABLE	2145	=item EV_STAT_ENABLE
1892		2146
1893	If undefined or defined to be C<1>, then stat watchers are supported. If	2147	If undefined or defined to be C<1>, then stat watchers are supported. If
		2148	defined to be C<0>, then they are not.
		2149
		2150	=item EV_FORK_ENABLE
		2151
		2152	If undefined or defined to be C<1>, then fork watchers are supported. If
1894	defined to be C<0>, then they are not.	2153	defined to be C<0>, then they are not.
1895		2154
1896	=item EV_MINIMAL	2155	=item EV_MINIMAL
1897		2156
1898	If you need to shave off some kilobytes of code at the expense of some	2157	If you need to shave off some kilobytes of code at the expense of some
1899	speed, define this symbol to C<1>. Currently only used for gcc to override	2158	speed, define this symbol to C<1>. Currently only used for gcc to override
1900	some inlining decisions, saves roughly 30% codesize of amd64.	2159	some inlining decisions, saves roughly 30% codesize of amd64.
		2160
		2161	=item EV_PID_HASHSIZE
		2162
		2163	C<ev_child> watchers use a small hash table to distribute workload by
		2164	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2165	than enough. If you need to manage thousands of children you might want to
		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).
1901		2175
1902	=item EV_COMMON	2176	=item EV_COMMON
1903		2177
1904	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
1905	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
…		…
1934	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
1935	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
1936	file.	2210	file.
1937		2211
1938	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
1939	that everybody includes and which overrides some autoconf choices:	2213	that everybody includes and which overrides some configure choices:
1940		2214
		2215	#define EV_MINIMAL 1
1941	#define EV_USE_POLL 0	2216	#define EV_USE_POLL 0
1942	#define EV_MULTIPLICITY 0	2217	#define EV_MULTIPLICITY 0
1943	#define EV_PERIODICS 0	2218	#define EV_PERIODIC_ENABLE 0
		2219	#define EV_STAT_ENABLE 0
		2220	#define EV_FORK_ENABLE 0
1944	#define EV_CONFIG_H <config.h>	2221	#define EV_CONFIG_H <config.h>
		2222	#define EV_MINPRI 0
		2223	#define EV_MAXPRI 0
1945		2224
1946	#include "ev++.h"	2225	#include "ev++.h"
1947		2226
1948	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:
1949		2228
…		…
1965		2244
1966	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2245	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
1967		2246
1968	=item Stopping check/prepare/idle watchers: O(1)	2247	=item Stopping check/prepare/idle watchers: O(1)
1969		2248
1970	=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))
1971		2250
1972	=item Finding the next timer per loop iteration: O(1)	2251	=item Finding the next timer per loop iteration: O(1)
1973		2252
1974	=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)
1975		2254

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Comparing libev/ev.pod (file contents): Revision 1.48 by root, Tue Nov 27 08:11:52 2007 UTC vs. Revision 1.68 by root, Fri Dec 7 18:09:43 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.48 by root, Tue Nov 27 08:11:52 2007 UTC vs.
Revision 1.68 by root, Fri Dec 7 18:09:43 2007 UTC