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

Comparing libev/ev.pod (file contents):
Revision 1.41 by root, Sat Nov 24 10:19:14 2007 UTC vs.
Revision 1.72 by root, Fri Dec 7 20:19:16 2007 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		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	}
		50
9	=head1 DESCRIPTION	51	=head1 DESCRIPTION
		52
		53	The newest version of this document is also available as a html-formatted
		54	web page you might find easier to navigate when reading it for the first
		55	time: L<http://cvs.schmorp.de/libev/ev.html>.
10		56
11	Libev is an event loop: you register interest in certain events (such as a	57	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	58	file descriptor being readable or a timeout occuring), and it will manage
13	these event sources and provide your program with events.	59	these event sources and provide your program with events.
14		60
…		…
21	details of the event, and then hand it over to libev by I<starting> the	67	details of the event, and then hand it over to libev by I<starting> the
22	watcher.	68	watcher.
23		69
24	=head1 FEATURES	70	=head1 FEATURES
25		71
26	Libev supports select, poll, the linux-specific epoll and the bsd-specific	72	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
27	kqueue mechanisms for file descriptor events, relative timers, absolute	73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
28	timers with customised rescheduling, signal events, process status change	74	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
29	events (related to SIGCHLD), and event watchers dealing with the event	75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
30	loop mechanism itself (idle, prepare and check watchers). It also is quite	76	with customised rescheduling (C<ev_periodic>), synchronous signals
		77	(C<ev_signal>), process status change events (C<ev_child>), and event
		78	watchers dealing with the event loop mechanism itself (C<ev_idle>,
		79	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
		80	file watchers (C<ev_stat>) and even limited support for fork events
		81	(C<ev_fork>).
		82
		83	It also is quite fast (see this
31	fast (see this L<benchmark\|http://libev.schmorp.de/bench.html> comparing	84	L<benchmark\|http://libev.schmorp.de/bench.html> comparing it to libevent
32	it to libevent for example).	85	for example).
33		86
34	=head1 CONVENTIONS	87	=head1 CONVENTIONS
35		88
36	Libev is very configurable. In this manual the default configuration	89	Libev is very configurable. In this manual the default configuration will
37	will be described, which supports multiple event loops. For more info	90	be described, which supports multiple event loops. For more info about
38	about various configuration options please have a look at the file	91	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	92	this manual. If libev was configured without support for multiple event
40	support for multiple event loops, then all functions taking an initial	93	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 *>)	94	(which is always of type C<struct ev_loop *>) will not have this argument.
42	will not have this argument.
43		95
44	=head1 TIME REPRESENTATION	96	=head1 TIME REPRESENTATION
45		97
46	Libev represents time as a single floating point number, representing the	98	Libev represents time as a single floating point number, representing the
47	(fractional) number of seconds since the (POSIX) epoch (somewhere near	99	(fractional) number of seconds since the (POSIX) epoch (somewhere near
48	the beginning of 1970, details are complicated, don't ask). This type is	100	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	101	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	102	to the C<double> type in C, and when you need to do any calculations on
51	it, you should treat it as such.	103	it, you should treat it as such.
52		104
53
54	=head1 GLOBAL FUNCTIONS	105	=head1 GLOBAL FUNCTIONS
55		106
56	These functions can be called anytime, even before initialising the	107	These functions can be called anytime, even before initialising the
57	library in any way.	108	library in any way.
58		109
…		…
77	Usually, it's a good idea to terminate if the major versions mismatch,	128	Usually, it's a good idea to terminate if the major versions mismatch,
78	as this indicates an incompatible change. Minor versions are usually	129	as this indicates an incompatible change. Minor versions are usually
79	compatible to older versions, so a larger minor version alone is usually	130	compatible to older versions, so a larger minor version alone is usually
80	not a problem.	131	not a problem.
81		132
82	Example: make sure we haven't accidentally been linked against the wrong	133	Example: Make sure we haven't accidentally been linked against the wrong
83	version:	134	version.
84		135
85	assert (("libev version mismatch",	136	assert (("libev version mismatch",
86	ev_version_major () == EV_VERSION_MAJOR	137	ev_version_major () == EV_VERSION_MAJOR
87	&& ev_version_minor () >= EV_VERSION_MINOR));	138	&& ev_version_minor () >= EV_VERSION_MINOR));
88		139
…		…
118		169
119	See the description of C<ev_embed> watchers for more info.	170	See the description of C<ev_embed> watchers for more info.
120		171
121	=item ev_set_allocator (void (cb)(void *ptr, long size))	172	=item ev_set_allocator (void (cb)(void *ptr, long size))
122		173
123	Sets the allocation function to use (the prototype is similar to the	174	Sets the allocation function to use (the prototype is similar - the
124	realloc C function, the semantics are identical). It is used to allocate	175	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	176	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	177	memory needs to be allocated, the library might abort or take some
127	destructive action. The default is your system realloc function.	178	potentially destructive action. The default is your system realloc
		179	function.
128		180
129	You could override this function in high-availability programs to, say,	181	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,	182	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.	183	or even to sleep a while and retry until some memory is available.
132		184
133	Example: replace the libev allocator with one that waits a bit and then	185	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	186	retries).
135		187
136	static void *	188	static void *
137	persistent_realloc (void *ptr, long size)	189	persistent_realloc (void *ptr, size_t size)
138	{	190	{
139	for (;;)	191	for (;;)
140	{	192	{
141	void *newptr = realloc (ptr, size);	193	void *newptr = realloc (ptr, size);
142		194
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	210	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	211	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	212	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	213	(such as abort).
162		214
163	Example: do the same thing as libev does internally:	215	Example: This is basically the same thing that libev does internally, too.
164		216
165	static void	217	static void
166	fatal_error (const char *msg)	218	fatal_error (const char *msg)
167	{	219	{
168	perror (msg);	220	perror (msg);
…		…
218	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	270	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
219	override the flags completely if it is found in the environment. This is	271	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	272	useful to try out specific backends to test their performance, or to work
221	around bugs.	273	around bugs.
222		274
		275	=item C<EVFLAG_FORKCHECK>
		276
		277	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		278	a fork, you can also make libev check for a fork in each iteration by
		279	enabling this flag.
		280
		281	This works by calling C<getpid ()> on every iteration of the loop,
		282	and thus this might slow down your event loop if you do a lot of loop
		283	iterations and little real work, but is usually not noticeable (on my
		284	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		285	without a syscall and thus I<very> fast, but my Linux system also has
		286	C<pthread_atfork> which is even faster).
		287
		288	The big advantage of this flag is that you can forget about fork (and
		289	forget about forgetting to tell libev about forking) when you use this
		290	flag.
		291
		292	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		293	environment variable.
		294
223	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	295	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
224		296
225	This is your standard select(2) backend. Not I<completely> standard, as	297	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,	298	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	299	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	386	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	387	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	388	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).	389	undefined behaviour (or a failed assertion if assertions are enabled).
318		390
319	Example: try to create a event loop that uses epoll and nothing else.	391	Example: Try to create a event loop that uses epoll and nothing else.
320		392
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	393	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
322	if (!epoller)	394	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	395	fatal ("no epoll found here, maybe it hides under your chair");
324		396
…		…
361	=item ev_loop_fork (loop)	433	=item ev_loop_fork (loop)
362		434
363	Like C<ev_default_fork>, but acts on an event loop created by	435	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	436	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.	437	after fork, and how you do this is entirely your own problem.
		438
		439	=item unsigned int ev_loop_count (loop)
		440
		441	Returns the count of loop iterations for the loop, which is identical to
		442	the number of times libev did poll for new events. It starts at C<0> and
		443	happily wraps around with enough iterations.
		444
		445	This value can sometimes be useful as a generation counter of sorts (it
		446	"ticks" the number of loop iterations), as it roughly corresponds with
		447	C<ev_prepare> and C<ev_check> calls.
366		448
367	=item unsigned int ev_backend (loop)	449	=item unsigned int ev_backend (loop)
368		450
369	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	451	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
370	use.	452	use.
…		…
423	Signals and child watchers are implemented as I/O watchers, and will	505	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	506	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	507	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	508	were used, return, otherwise continue with step *.
427		509
428	Example: queue some jobs and then loop until no events are outsanding	510	Example: Queue some jobs and then loop until no events are outsanding
429	anymore.	511	anymore.
430		512
431	... queue jobs here, make sure they register event watchers as long	513	... 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..)	514	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	515	ev_loop (my_loop, 0);
…		…
453	visible to the libev user and should not keep C<ev_loop> from exiting if	535	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	536	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	537	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>.	538	libraries. Just remember to I<unref after start> and I<ref before stop>.
457		539
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	540	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	541	running when nothing else is active.
460		542
461	struct dv_signal exitsig;	543	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	544	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	545	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	546	evf_unref (loop);
465		547
466	Example: for some weird reason, unregister the above signal handler again.	548	Example: For some weird reason, unregister the above signal handler again.
467		549
468	ev_ref (myloop);	550	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	551	ev_signal_stop (loop, &exitsig);
470		552
471	=back	553	=back
		554
472		555
473	=head1 ANATOMY OF A WATCHER	556	=head1 ANATOMY OF A WATCHER
474		557
475	A watcher is a structure that you create and register to record your	558	A watcher is a structure that you create and register to record your
476	interest in some event. For instance, if you want to wait for STDIN to	559	interest in some event. For instance, if you want to wait for STDIN to
…		…
543	The signal specified in the C<ev_signal> watcher has been received by a thread.	626	The signal specified in the C<ev_signal> watcher has been received by a thread.
544		627
545	=item C<EV_CHILD>	628	=item C<EV_CHILD>
546		629
547	The pid specified in the C<ev_child> watcher has received a status change.	630	The pid specified in the C<ev_child> watcher has received a status change.
		631
		632	=item C<EV_STAT>
		633
		634	The path specified in the C<ev_stat> watcher changed its attributes somehow.
548		635
549	=item C<EV_IDLE>	636	=item C<EV_IDLE>
550		637
551	The C<ev_idle> watcher has determined that you have nothing better to do.	638	The C<ev_idle> watcher has determined that you have nothing better to do.
552		639
…		…
560	received events. Callbacks of both watcher types can start and stop as	647	received events. Callbacks of both watcher types can start and stop as
561	many watchers as they want, and all of them will be taken into account	648	many watchers as they want, and all of them will be taken into account
562	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	649	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
563	C<ev_loop> from blocking).	650	C<ev_loop> from blocking).
564		651
		652	=item C<EV_EMBED>
		653
		654	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		655
		656	=item C<EV_FORK>
		657
		658	The event loop has been resumed in the child process after fork (see
		659	C<ev_fork>).
		660
565	=item C<EV_ERROR>	661	=item C<EV_ERROR>
566		662
567	An unspecified error has occured, the watcher has been stopped. This might	663	An unspecified error has occured, the watcher has been stopped. This might
568	happen because the watcher could not be properly started because libev	664	happen because the watcher could not be properly started because libev
569	ran out of memory, a file descriptor was found to be closed or any other	665	ran out of memory, a file descriptor was found to be closed or any other
…		…
576	with the error from read() or write(). This will not work in multithreaded	672	with the error from read() or write(). This will not work in multithreaded
577	programs, though, so beware.	673	programs, though, so beware.
578		674
579	=back	675	=back
580		676
581	=head2 SUMMARY OF GENERIC WATCHER FUNCTIONS	677	=head2 GENERIC WATCHER FUNCTIONS
582		678
583	In the following description, C<TYPE> stands for the watcher type,	679	In the following description, C<TYPE> stands for the watcher type,
584	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.	680	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.
585		681
586	=over 4	682	=over 4
…		…
595	which rolls both calls into one.	691	which rolls both calls into one.
596		692
597	You can reinitialise a watcher at any time as long as it has been stopped	693	You can reinitialise a watcher at any time as long as it has been stopped
598	(or never started) and there are no pending events outstanding.	694	(or never started) and there are no pending events outstanding.
599		695
600	The callbakc is always of type C<void ()(ev_loop loop, ev_TYPE *watcher,	696	The callback is always of type C<void ()(ev_loop loop, ev_TYPE *watcher,
601	int revents)>.	697	int revents)>.
602		698
603	=item C<ev_TYPE_set> (ev_TYPE *, [args])	699	=item C<ev_TYPE_set> (ev_TYPE *, [args])
604		700
605	This macro initialises the type-specific parts of a watcher. You need to	701	This macro initialises the type-specific parts of a watcher. You need to
…		…
643	events but its callback has not yet been invoked). As long as a watcher	739	events but its callback has not yet been invoked). As long as a watcher
644	is pending (but not active) you must not call an init function on it (but	740	is pending (but not active) you must not call an init function on it (but
645	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	741	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to
646	libev (e.g. you cnanot C<free ()> it).	742	libev (e.g. you cnanot C<free ()> it).
647		743
648	=item callback = ev_cb (ev_TYPE *watcher)	744	=item callback ev_cb (ev_TYPE *watcher)
649		745
650	Returns the callback currently set on the watcher.	746	Returns the callback currently set on the watcher.
651		747
652	=item ev_cb_set (ev_TYPE *watcher, callback)	748	=item ev_cb_set (ev_TYPE *watcher, callback)
653		749
654	Change the callback. You can change the callback at virtually any time	750	Change the callback. You can change the callback at virtually any time
655	(modulo threads).	751	(modulo threads).
		752
		753	=item ev_set_priority (ev_TYPE *watcher, priority)
		754
		755	=item int ev_priority (ev_TYPE *watcher)
		756
		757	Set and query the priority of the watcher. The priority is a small
		758	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		759	(default: C<-2>). Pending watchers with higher priority will be invoked
		760	before watchers with lower priority, but priority will not keep watchers
		761	from being executed (except for C<ev_idle> watchers).
		762
		763	This means that priorities are I<only> used for ordering callback
		764	invocation after new events have been received. This is useful, for
		765	example, to reduce latency after idling, or more often, to bind two
		766	watchers on the same event and make sure one is called first.
		767
		768	If you need to suppress invocation when higher priority events are pending
		769	you need to look at C<ev_idle> watchers, which provide this functionality.
		770
		771	The default priority used by watchers when no priority has been set is
		772	always C<0>, which is supposed to not be too high and not be too low :).
		773
		774	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		775	fine, as long as you do not mind that the priority value you query might
		776	or might not have been adjusted to be within valid range.
656		777
657	=back	778	=back
658		779
659		780
660	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	781	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
681	{	802	{
682	struct my_io w = (struct my_io )w_;	803	struct my_io w = (struct my_io )w_;
683	...	804	...
684	}	805	}
685		806
686	More interesting and less C-conformant ways of catsing your callback type	807	More interesting and less C-conformant ways of casting your callback type
687	have been omitted....	808	instead have been omitted.
		809
		810	Another common scenario is having some data structure with multiple
		811	watchers:
		812
		813	struct my_biggy
		814	{
		815	int some_data;
		816	ev_timer t1;
		817	ev_timer t2;
		818	}
		819
		820	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		821	you need to use C<offsetof>:
		822
		823	#include <stddef.h>
		824
		825	static void
		826	t1_cb (EV_P_ struct ev_timer *w, int revents)
		827	{
		828	struct my_biggy big = (struct my_biggy *
		829	(((char *)w) - offsetof (struct my_biggy, t1));
		830	}
		831
		832	static void
		833	t2_cb (EV_P_ struct ev_timer *w, int revents)
		834	{
		835	struct my_biggy big = (struct my_biggy *
		836	(((char *)w) - offsetof (struct my_biggy, t2));
		837	}
688		838
689		839
690	=head1 WATCHER TYPES	840	=head1 WATCHER TYPES
691		841
692	This section describes each watcher in detail, but will not repeat	842	This section describes each watcher in detail, but will not repeat
693	information given in the last section.	843	information given in the last section. Any initialisation/set macros,
		844	functions and members specific to the watcher type are explained.
694		845
		846	Members are additionally marked with either I<[read-only]>, meaning that,
		847	while the watcher is active, you can look at the member and expect some
		848	sensible content, but you must not modify it (you can modify it while the
		849	watcher is stopped to your hearts content), or I<[read-write]>, which
		850	means you can expect it to have some sensible content while the watcher
		851	is active, but you can also modify it. Modifying it may not do something
		852	sensible or take immediate effect (or do anything at all), but libev will
		853	not crash or malfunction in any way.
695		854
		855
696	=head2 C<ev_io> - is this file descriptor readable or writable	856	=head2 C<ev_io> - is this file descriptor readable or writable?
697		857
698	I/O watchers check whether a file descriptor is readable or writable	858	I/O watchers check whether a file descriptor is readable or writable
699	in each iteration of the event loop (This behaviour is called	859	in each iteration of the event loop, or, more precisely, when reading
700	level-triggering because you keep receiving events as long as the	860	would not block the process and writing would at least be able to write
701	condition persists. Remember you can stop the watcher if you don't want to	861	some data. This behaviour is called level-triggering because you keep
702	act on the event and neither want to receive future events).	862	receiving events as long as the condition persists. Remember you can stop
		863	the watcher if you don't want to act on the event and neither want to
		864	receive future events.
703		865
704	In general you can register as many read and/or write event watchers per	866	In general you can register as many read and/or write event watchers per
705	fd as you want (as long as you don't confuse yourself). Setting all file	867	fd as you want (as long as you don't confuse yourself). Setting all file
706	descriptors to non-blocking mode is also usually a good idea (but not	868	descriptors to non-blocking mode is also usually a good idea (but not
707	required if you know what you are doing).	869	required if you know what you are doing).
708		870
709	You have to be careful with dup'ed file descriptors, though. Some backends	871	You have to be careful with dup'ed file descriptors, though. Some backends
710	(the linux epoll backend is a notable example) cannot handle dup'ed file	872	(the linux epoll backend is a notable example) cannot handle dup'ed file
711	descriptors correctly if you register interest in two or more fds pointing	873	descriptors correctly if you register interest in two or more fds pointing
712	to the same underlying file/socket etc. description (that is, they share	874	to the same underlying file/socket/etc. description (that is, they share
713	the same underlying "file open").	875	the same underlying "file open").
714		876
715	If you must do this, then force the use of a known-to-be-good backend	877	If you must do this, then force the use of a known-to-be-good backend
716	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	878	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
717	C<EVBACKEND_POLL>).	879	C<EVBACKEND_POLL>).
718		880
		881	Another thing you have to watch out for is that it is quite easy to
		882	receive "spurious" readyness notifications, that is your callback might
		883	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
		884	because there is no data. Not only are some backends known to create a
		885	lot of those (for example solaris ports), it is very easy to get into
		886	this situation even with a relatively standard program structure. Thus
		887	it is best to always use non-blocking I/O: An extra C<read>(2) returning
		888	C<EAGAIN> is far preferable to a program hanging until some data arrives.
		889
		890	If you cannot run the fd in non-blocking mode (for example you should not
		891	play around with an Xlib connection), then you have to seperately re-test
		892	whether a file descriptor is really ready with a known-to-be good interface
		893	such as poll (fortunately in our Xlib example, Xlib already does this on
		894	its own, so its quite safe to use).
		895
719	=over 4	896	=over 4
720		897
721	=item ev_io_init (ev_io *, callback, int fd, int events)	898	=item ev_io_init (ev_io *, callback, int fd, int events)
722		899
723	=item ev_io_set (ev_io *, int fd, int events)	900	=item ev_io_set (ev_io *, int fd, int events)
724		901
725	Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive	902	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
726	events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ \|	903	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
727	EV_WRITE> to receive the given events.	904	C<EV_READ \| EV_WRITE> to receive the given events.
728		905
729	Please note that most of the more scalable backend mechanisms (for example	906	=item int fd [read-only]
730	epoll and solaris ports) can result in spurious readyness notifications	907
731	for file descriptors, so you practically need to use non-blocking I/O (and	908	The file descriptor being watched.
732	treat callback invocation as hint only), or retest separately with a safe	909
733	interface before doing I/O (XLib can do this), or force the use of either	910	=item int events [read-only]
734	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this	911
735	problem. Also note that it is quite easy to have your callback invoked	912	The events being watched.
736	when the readyness condition is no longer valid even when employing
737	typical ways of handling events, so its a good idea to use non-blocking
738	I/O unconditionally.
739		913
740	=back	914	=back
741		915
742	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	916	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
743	readable, but only once. Since it is likely line-buffered, you could	917	readable, but only once. Since it is likely line-buffered, you could
744	attempt to read a whole line in the callback:	918	attempt to read a whole line in the callback.
745		919
746	static void	920	static void
747	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	921	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
748	{	922	{
749	ev_io_stop (loop, w);	923	ev_io_stop (loop, w);
…		…
756	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	930	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
757	ev_io_start (loop, &stdin_readable);	931	ev_io_start (loop, &stdin_readable);
758	ev_loop (loop, 0);	932	ev_loop (loop, 0);
759		933
760		934
761	=head2 C<ev_timer> - relative and optionally recurring timeouts	935	=head2 C<ev_timer> - relative and optionally repeating timeouts
762		936
763	Timer watchers are simple relative timers that generate an event after a	937	Timer watchers are simple relative timers that generate an event after a
764	given time, and optionally repeating in regular intervals after that.	938	given time, and optionally repeating in regular intervals after that.
765		939
766	The timers are based on real time, that is, if you register an event that	940	The timers are based on real time, that is, if you register an event that
…		…
801	=item ev_timer_again (loop)	975	=item ev_timer_again (loop)
802		976
803	This will act as if the timer timed out and restart it again if it is	977	This will act as if the timer timed out and restart it again if it is
804	repeating. The exact semantics are:	978	repeating. The exact semantics are:
805		979
		980	If the timer is pending, its pending status is cleared.
		981
806	If the timer is started but nonrepeating, stop it.	982	If the timer is started but nonrepeating, stop it (as if it timed out).
807		983
808	If the timer is repeating, either start it if necessary (with the repeat	984	If the timer is repeating, either start it if necessary (with the
809	value), or reset the running timer to the repeat value.	985	C<repeat> value), or reset the running timer to the C<repeat> value.
810		986
811	This sounds a bit complicated, but here is a useful and typical	987	This sounds a bit complicated, but here is a useful and typical
812	example: Imagine you have a tcp connection and you want a so-called idle	988	example: Imagine you have a tcp connection and you want a so-called idle
813	timeout, that is, you want to be called when there have been, say, 60	989	timeout, that is, you want to be called when there have been, say, 60
814	seconds of inactivity on the socket. The easiest way to do this is to	990	seconds of inactivity on the socket. The easiest way to do this is to
815	configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each	991	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
816	time you successfully read or write some data. If you go into an idle	992	C<ev_timer_again> each time you successfully read or write some data. If
817	state where you do not expect data to travel on the socket, you can stop	993	you go into an idle state where you do not expect data to travel on the
818	the timer, and again will automatically restart it if need be.	994	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
		995	automatically restart it if need be.
		996
		997	That means you can ignore the C<after> value and C<ev_timer_start>
		998	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
		999
		1000	ev_timer_init (timer, callback, 0., 5.);
		1001	ev_timer_again (loop, timer);
		1002	...
		1003	timer->again = 17.;
		1004	ev_timer_again (loop, timer);
		1005	...
		1006	timer->again = 10.;
		1007	ev_timer_again (loop, timer);
		1008
		1009	This is more slightly efficient then stopping/starting the timer each time
		1010	you want to modify its timeout value.
		1011
		1012	=item ev_tstamp repeat [read-write]
		1013
		1014	The current C<repeat> value. Will be used each time the watcher times out
		1015	or C<ev_timer_again> is called and determines the next timeout (if any),
		1016	which is also when any modifications are taken into account.
819		1017
820	=back	1018	=back
821		1019
822	Example: create a timer that fires after 60 seconds.	1020	Example: Create a timer that fires after 60 seconds.
823		1021
824	static void	1022	static void
825	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	1023	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
826	{	1024	{
827	.. one minute over, w is actually stopped right here	1025	.. one minute over, w is actually stopped right here
…		…
829		1027
830	struct ev_timer mytimer;	1028	struct ev_timer mytimer;
831	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1029	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
832	ev_timer_start (loop, &mytimer);	1030	ev_timer_start (loop, &mytimer);
833		1031
834	Example: create a timeout timer that times out after 10 seconds of	1032	Example: Create a timeout timer that times out after 10 seconds of
835	inactivity.	1033	inactivity.
836		1034
837	static void	1035	static void
838	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1036	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
839	{	1037	{
…		…
848	// and in some piece of code that gets executed on any "activity":	1046	// and in some piece of code that gets executed on any "activity":
849	// reset the timeout to start ticking again at 10 seconds	1047	// reset the timeout to start ticking again at 10 seconds
850	ev_timer_again (&mytimer);	1048	ev_timer_again (&mytimer);
851		1049
852		1050
853	=head2 C<ev_periodic> - to cron or not to cron	1051	=head2 C<ev_periodic> - to cron or not to cron?
854		1052
855	Periodic watchers are also timers of a kind, but they are very versatile	1053	Periodic watchers are also timers of a kind, but they are very versatile
856	(and unfortunately a bit complex).	1054	(and unfortunately a bit complex).
857		1055
858	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1056	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
…		…
950	Simply stops and restarts the periodic watcher again. This is only useful	1148	Simply stops and restarts the periodic watcher again. This is only useful
951	when you changed some parameters or the reschedule callback would return	1149	when you changed some parameters or the reschedule callback would return
952	a different time than the last time it was called (e.g. in a crond like	1150	a different time than the last time it was called (e.g. in a crond like
953	program when the crontabs have changed).	1151	program when the crontabs have changed).
954		1152
		1153	=item ev_tstamp interval [read-write]
		1154
		1155	The current interval value. Can be modified any time, but changes only
		1156	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1157	called.
		1158
		1159	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
		1160
		1161	The current reschedule callback, or C<0>, if this functionality is
		1162	switched off. Can be changed any time, but changes only take effect when
		1163	the periodic timer fires or C<ev_periodic_again> is being called.
		1164
955	=back	1165	=back
956		1166
957	Example: call a callback every hour, or, more precisely, whenever the	1167	Example: Call a callback every hour, or, more precisely, whenever the
958	system clock is divisible by 3600. The callback invocation times have	1168	system clock is divisible by 3600. The callback invocation times have
959	potentially a lot of jittering, but good long-term stability.	1169	potentially a lot of jittering, but good long-term stability.
960		1170
961	static void	1171	static void
962	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1172	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
966		1176
967	struct ev_periodic hourly_tick;	1177	struct ev_periodic hourly_tick;
968	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1178	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
969	ev_periodic_start (loop, &hourly_tick);	1179	ev_periodic_start (loop, &hourly_tick);
970		1180
971	Example: the same as above, but use a reschedule callback to do it:	1181	Example: The same as above, but use a reschedule callback to do it:
972		1182
973	#include <math.h>	1183	#include <math.h>
974		1184
975	static ev_tstamp	1185	static ev_tstamp
976	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1186	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
978	return fmod (now, 3600.) + 3600.;	1188	return fmod (now, 3600.) + 3600.;
979	}	1189	}
980		1190
981	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1191	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
982		1192
983	Example: call a callback every hour, starting now:	1193	Example: Call a callback every hour, starting now:
984		1194
985	struct ev_periodic hourly_tick;	1195	struct ev_periodic hourly_tick;
986	ev_periodic_init (&hourly_tick, clock_cb,	1196	ev_periodic_init (&hourly_tick, clock_cb,
987	fmod (ev_now (loop), 3600.), 3600., 0);	1197	fmod (ev_now (loop), 3600.), 3600., 0);
988	ev_periodic_start (loop, &hourly_tick);	1198	ev_periodic_start (loop, &hourly_tick);
989		1199
990		1200
991	=head2 C<ev_signal> - signal me when a signal gets signalled	1201	=head2 C<ev_signal> - signal me when a signal gets signalled!
992		1202
993	Signal watchers will trigger an event when the process receives a specific	1203	Signal watchers will trigger an event when the process receives a specific
994	signal one or more times. Even though signals are very asynchronous, libev	1204	signal one or more times. Even though signals are very asynchronous, libev
995	will try it's best to deliver signals synchronously, i.e. as part of the	1205	will try it's best to deliver signals synchronously, i.e. as part of the
996	normal event processing, like any other event.	1206	normal event processing, like any other event.
…		…
1009	=item ev_signal_set (ev_signal *, int signum)	1219	=item ev_signal_set (ev_signal *, int signum)
1010		1220
1011	Configures the watcher to trigger on the given signal number (usually one	1221	Configures the watcher to trigger on the given signal number (usually one
1012	of the C<SIGxxx> constants).	1222	of the C<SIGxxx> constants).
1013		1223
		1224	=item int signum [read-only]
		1225
		1226	The signal the watcher watches out for.
		1227
1014	=back	1228	=back
1015		1229
1016		1230
1017	=head2 C<ev_child> - wait for pid status changes	1231	=head2 C<ev_child> - watch out for process status changes
1018		1232
1019	Child watchers trigger when your process receives a SIGCHLD in response to	1233	Child watchers trigger when your process receives a SIGCHLD in response to
1020	some child status changes (most typically when a child of yours dies).	1234	some child status changes (most typically when a child of yours dies).
1021		1235
1022	=over 4	1236	=over 4
…		…
1030	at the C<rstatus> member of the C<ev_child> watcher structure to see	1244	at the C<rstatus> member of the C<ev_child> watcher structure to see
1031	the status word (use the macros from C<sys/wait.h> and see your systems	1245	the status word (use the macros from C<sys/wait.h> and see your systems
1032	C<waitpid> documentation). The C<rpid> member contains the pid of the	1246	C<waitpid> documentation). The C<rpid> member contains the pid of the
1033	process causing the status change.	1247	process causing the status change.
1034		1248
		1249	=item int pid [read-only]
		1250
		1251	The process id this watcher watches out for, or C<0>, meaning any process id.
		1252
		1253	=item int rpid [read-write]
		1254
		1255	The process id that detected a status change.
		1256
		1257	=item int rstatus [read-write]
		1258
		1259	The process exit/trace status caused by C<rpid> (see your systems
		1260	C<waitpid> and C<sys/wait.h> documentation for details).
		1261
1035	=back	1262	=back
1036		1263
1037	Example: try to exit cleanly on SIGINT and SIGTERM.	1264	Example: Try to exit cleanly on SIGINT and SIGTERM.
1038		1265
1039	static void	1266	static void
1040	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1267	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1041	{	1268	{
1042	ev_unloop (loop, EVUNLOOP_ALL);	1269	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1045	struct ev_signal signal_watcher;	1272	struct ev_signal signal_watcher;
1046	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1273	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1047	ev_signal_start (loop, &sigint_cb);	1274	ev_signal_start (loop, &sigint_cb);
1048		1275
1049		1276
		1277	=head2 C<ev_stat> - did the file attributes just change?
		1278
		1279	This watches a filesystem path for attribute changes. That is, it calls
		1280	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1281	compared to the last time, invoking the callback if it did.
		1282
		1283	The path does not need to exist: changing from "path exists" to "path does
		1284	not exist" is a status change like any other. The condition "path does
		1285	not exist" is signified by the C<st_nlink> field being zero (which is
		1286	otherwise always forced to be at least one) and all the other fields of
		1287	the stat buffer having unspecified contents.
		1288
		1289	The path I<should> be absolute and I<must not> end in a slash. If it is
		1290	relative and your working directory changes, the behaviour is undefined.
		1291
		1292	Since there is no standard to do this, the portable implementation simply
		1293	calls C<stat (2)> regularly on the path to see if it changed somehow. You
		1294	can specify a recommended polling interval for this case. If you specify
		1295	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1296	unspecified default> value will be used (which you can expect to be around
		1297	five seconds, although this might change dynamically). Libev will also
		1298	impose a minimum interval which is currently around C<0.1>, but thats
		1299	usually overkill.
		1300
		1301	This watcher type is not meant for massive numbers of stat watchers,
		1302	as even with OS-supported change notifications, this can be
		1303	resource-intensive.
		1304
		1305	At the time of this writing, only the Linux inotify interface is
		1306	implemented (implementing kqueue support is left as an exercise for the
		1307	reader). Inotify will be used to give hints only and should not change the
		1308	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1309	to fall back to regular polling again even with inotify, but changes are
		1310	usually detected immediately, and if the file exists there will be no
		1311	polling.
		1312
		1313	=over 4
		1314
		1315	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
		1316
		1317	=item ev_stat_set (ev_stat , const char path, ev_tstamp interval)
		1318
		1319	Configures the watcher to wait for status changes of the given
		1320	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1321	be detected and should normally be specified as C<0> to let libev choose
		1322	a suitable value. The memory pointed to by C<path> must point to the same
		1323	path for as long as the watcher is active.
		1324
		1325	The callback will be receive C<EV_STAT> when a change was detected,
		1326	relative to the attributes at the time the watcher was started (or the
		1327	last change was detected).
		1328
		1329	=item ev_stat_stat (ev_stat *)
		1330
		1331	Updates the stat buffer immediately with new values. If you change the
		1332	watched path in your callback, you could call this fucntion to avoid
		1333	detecting this change (while introducing a race condition). Can also be
		1334	useful simply to find out the new values.
		1335
		1336	=item ev_statdata attr [read-only]
		1337
		1338	The most-recently detected attributes of the file. Although the type is of
		1339	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1340	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1341	was some error while C<stat>ing the file.
		1342
		1343	=item ev_statdata prev [read-only]
		1344
		1345	The previous attributes of the file. The callback gets invoked whenever
		1346	C<prev> != C<attr>.
		1347
		1348	=item ev_tstamp interval [read-only]
		1349
		1350	The specified interval.
		1351
		1352	=item const char *path [read-only]
		1353
		1354	The filesystem path that is being watched.
		1355
		1356	=back
		1357
		1358	Example: Watch C</etc/passwd> for attribute changes.
		1359
		1360	static void
		1361	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1362	{
		1363	/* /etc/passwd changed in some way */
		1364	if (w->attr.st_nlink)
		1365	{
		1366	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1367	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1368	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1369	}
		1370	else
		1371	/* you shalt not abuse printf for puts */
		1372	puts ("wow, /etc/passwd is not there, expect problems. "
		1373	"if this is windows, they already arrived\n");
		1374	}
		1375
		1376	...
		1377	ev_stat passwd;
		1378
		1379	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1380	ev_stat_start (loop, &passwd);
		1381
		1382
1050	=head2 C<ev_idle> - when you've got nothing better to do	1383	=head2 C<ev_idle> - when you've got nothing better to do...
1051		1384
1052	Idle watchers trigger events when there are no other events are pending	1385	Idle watchers trigger events when no other events of the same or higher
1053	(prepare, check and other idle watchers do not count). That is, as long	1386	priority are pending (prepare, check and other idle watchers do not
1054	as your process is busy handling sockets or timeouts (or even signals,	1387	count).
1055	imagine) it will not be triggered. But when your process is idle all idle	1388
1056	watchers are being called again and again, once per event loop iteration -	1389	That is, as long as your process is busy handling sockets or timeouts
		1390	(or even signals, imagine) of the same or higher priority it will not be
		1391	triggered. But when your process is idle (or only lower-priority watchers
		1392	are pending), the idle watchers are being called once per event loop
1057	until stopped, that is, or your process receives more events and becomes	1393	iteration - until stopped, that is, or your process receives more events
1058	busy.	1394	and becomes busy again with higher priority stuff.
1059		1395
1060	The most noteworthy effect is that as long as any idle watchers are	1396	The most noteworthy effect is that as long as any idle watchers are
1061	active, the process will not block when waiting for new events.	1397	active, the process will not block when waiting for new events.
1062		1398
1063	Apart from keeping your process non-blocking (which is a useful	1399	Apart from keeping your process non-blocking (which is a useful
…		…
1073	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1409	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1074	believe me.	1410	believe me.
1075		1411
1076	=back	1412	=back
1077		1413
1078	Example: dynamically allocate an C<ev_idle>, start it, and in the	1414	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1079	callback, free it. Alos, use no error checking, as usual.	1415	callback, free it. Also, use no error checking, as usual.
1080		1416
1081	static void	1417	static void
1082	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1418	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1083	{	1419	{
1084	free (w);	1420	free (w);
…		…
1089	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1425	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1090	ev_idle_init (idle_watcher, idle_cb);	1426	ev_idle_init (idle_watcher, idle_cb);
1091	ev_idle_start (loop, idle_cb);	1427	ev_idle_start (loop, idle_cb);
1092		1428
1093		1429
1094	=head2 C<ev_prepare> and C<ev_check> - customise your event loop	1430	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1095		1431
1096	Prepare and check watchers are usually (but not always) used in tandem:	1432	Prepare and check watchers are usually (but not always) used in tandem:
1097	prepare watchers get invoked before the process blocks and check watchers	1433	prepare watchers get invoked before the process blocks and check watchers
1098	afterwards.	1434	afterwards.
1099		1435
		1436	You I<must not> call C<ev_loop> or similar functions that enter
		1437	the current event loop from either C<ev_prepare> or C<ev_check>
		1438	watchers. Other loops than the current one are fine, however. The
		1439	rationale behind this is that you do not need to check for recursion in
		1440	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
		1441	C<ev_check> so if you have one watcher of each kind they will always be
		1442	called in pairs bracketing the blocking call.
		1443
1100	Their main purpose is to integrate other event mechanisms into libev and	1444	Their main purpose is to integrate other event mechanisms into libev and
1101	their use is somewhat advanced. This could be used, for example, to track	1445	their use is somewhat advanced. This could be used, for example, to track
1102	variable changes, implement your own watchers, integrate net-snmp or a	1446	variable changes, implement your own watchers, integrate net-snmp or a
1103	coroutine library and lots more.	1447	coroutine library and lots more. They are also occasionally useful if
		1448	you cache some data and want to flush it before blocking (for example,
		1449	in X programs you might want to do an C<XFlush ()> in an C<ev_prepare>
		1450	watcher).
1104		1451
1105	This is done by examining in each prepare call which file descriptors need	1452	This is done by examining in each prepare call which file descriptors need
1106	to be watched by the other library, registering C<ev_io> watchers for	1453	to be watched by the other library, registering C<ev_io> watchers for
1107	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1454	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1108	provide just this functionality). Then, in the check watcher you check for	1455	provide just this functionality). Then, in the check watcher you check for
…		…
1130	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1477	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1131	macros, but using them is utterly, utterly and completely pointless.	1478	macros, but using them is utterly, utterly and completely pointless.
1132		1479
1133	=back	1480	=back
1134		1481
1135	Example: TODO.	1482	Example: To include a library such as adns, you would add IO watchers
		1483	and a timeout watcher in a prepare handler, as required by libadns, and
		1484	in a check watcher, destroy them and call into libadns. What follows is
		1485	pseudo-code only of course:
1136		1486
		1487	static ev_io iow [nfd];
		1488	static ev_timer tw;
1137		1489
		1490	static void
		1491	io_cb (ev_loop loop, ev_io w, int revents)
		1492	{
		1493	// set the relevant poll flags
		1494	// could also call adns_processreadable etc. here
		1495	struct pollfd fd = (struct pollfd )w->data;
		1496	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1497	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1498	}
		1499
		1500	// create io watchers for each fd and a timer before blocking
		1501	static void
		1502	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1503	{
		1504	int timeout = 3600000;
		1505	struct pollfd fds [nfd];
		1506	// actual code will need to loop here and realloc etc.
		1507	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1508
		1509	/* the callback is illegal, but won't be called as we stop during check */
		1510	ev_timer_init (&tw, 0, timeout * 1e-3);
		1511	ev_timer_start (loop, &tw);
		1512
		1513	// create on ev_io per pollfd
		1514	for (int i = 0; i < nfd; ++i)
		1515	{
		1516	ev_io_init (iow + i, io_cb, fds [i].fd,
		1517	((fds [i].events & POLLIN ? EV_READ : 0)
		1518	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1519
		1520	fds [i].revents = 0;
		1521	iow [i].data = fds + i;
		1522	ev_io_start (loop, iow + i);
		1523	}
		1524	}
		1525
		1526	// stop all watchers after blocking
		1527	static void
		1528	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1529	{
		1530	ev_timer_stop (loop, &tw);
		1531
		1532	for (int i = 0; i < nfd; ++i)
		1533	ev_io_stop (loop, iow + i);
		1534
		1535	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1536	}
		1537
		1538
1138	=head2 C<ev_embed> - when one backend isn't enough	1539	=head2 C<ev_embed> - when one backend isn't enough...
1139		1540
1140	This is a rather advanced watcher type that lets you embed one event loop	1541	This is a rather advanced watcher type that lets you embed one event loop
1141	into another (currently only C<ev_io> events are supported in the embedded	1542	into another (currently only C<ev_io> events are supported in the embedded
1142	loop, other types of watchers might be handled in a delayed or incorrect	1543	loop, other types of watchers might be handled in a delayed or incorrect
1143	fashion and must not be used).	1544	fashion and must not be used).
…		…
1221		1622
1222	Make a single, non-blocking sweep over the embedded loop. This works	1623	Make a single, non-blocking sweep over the embedded loop. This works
1223	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1624	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1224	apropriate way for embedded loops.	1625	apropriate way for embedded loops.
1225		1626
		1627	=item struct ev_loop *loop [read-only]
		1628
		1629	The embedded event loop.
		1630
		1631	=back
		1632
		1633
		1634	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1635
		1636	Fork watchers are called when a C<fork ()> was detected (usually because
		1637	whoever is a good citizen cared to tell libev about it by calling
		1638	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1639	event loop blocks next and before C<ev_check> watchers are being called,
		1640	and only in the child after the fork. If whoever good citizen calling
		1641	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1642	handlers will be invoked, too, of course.
		1643
		1644	=over 4
		1645
		1646	=item ev_fork_init (ev_signal *, callback)
		1647
		1648	Initialises and configures the fork watcher - it has no parameters of any
		1649	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1650	believe me.
		1651
1226	=back	1652	=back
1227		1653
1228		1654
1229	=head1 OTHER FUNCTIONS	1655	=head1 OTHER FUNCTIONS
1230		1656
…		…
1318		1744
1319	To use it,	1745	To use it,
1320		1746
1321	#include <ev++.h>	1747	#include <ev++.h>
1322		1748
1323	(it is not installed by default). This automatically includes F<ev.h>	1749	This automatically includes F<ev.h> and puts all of its definitions (many
1324	and puts all of its definitions (many of them macros) into the global	1750	of them macros) into the global namespace. All C++ specific things are
1325	namespace. All C++ specific things are put into the C<ev> namespace.	1751	put into the C<ev> namespace. It should support all the same embedding
		1752	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1326		1753
1327	It should support all the same embedding options as F<ev.h>, most notably	1754	Care has been taken to keep the overhead low. The only data member the C++
1328	C<EV_MULTIPLICITY>.	1755	classes add (compared to plain C-style watchers) is the event loop pointer
		1756	that the watcher is associated with (or no additional members at all if
		1757	you disable C<EV_MULTIPLICITY> when embedding libev).
		1758
		1759	Currently, functions, and static and non-static member functions can be
		1760	used as callbacks. Other types should be easy to add as long as they only
		1761	need one additional pointer for context. If you need support for other
		1762	types of functors please contact the author (preferably after implementing
		1763	it).
1329		1764
1330	Here is a list of things available in the C<ev> namespace:	1765	Here is a list of things available in the C<ev> namespace:
1331		1766
1332	=over 4	1767	=over 4
1333		1768
…		…
1349		1784
1350	All of those classes have these methods:	1785	All of those classes have these methods:
1351		1786
1352	=over 4	1787	=over 4
1353		1788
1354	=item ev::TYPE::TYPE (object , object::method )	1789	=item ev::TYPE::TYPE ()
1355		1790
1356	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1791	=item ev::TYPE::TYPE (struct ev_loop *)
1357		1792
1358	=item ev::TYPE::~TYPE	1793	=item ev::TYPE::~TYPE
1359		1794
1360	The constructor takes a pointer to an object and a method pointer to	1795	The constructor (optionally) takes an event loop to associate the watcher
1361	the event handler callback to call in this class. The constructor calls	1796	with. If it is omitted, it will use C<EV_DEFAULT>.
1362	C<ev_init> for you, which means you have to call the C<set> method	1797
1363	before starting it. If you do not specify a loop then the constructor	1798	The constructor calls C<ev_init> for you, which means you have to call the
1364	automatically associates the default loop with this watcher.	1799	C<set> method before starting it.
		1800
		1801	It will not set a callback, however: You have to call the templated C<set>
		1802	method to set a callback before you can start the watcher.
		1803
		1804	(The reason why you have to use a method is a limitation in C++ which does
		1805	not allow explicit template arguments for constructors).
1365		1806
1366	The destructor automatically stops the watcher if it is active.	1807	The destructor automatically stops the watcher if it is active.
		1808
		1809	=item w->set<class, &class::method> (object *)
		1810
		1811	This method sets the callback method to call. The method has to have a
		1812	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1813	first argument and the C<revents> as second. The object must be given as
		1814	parameter and is stored in the C<data> member of the watcher.
		1815
		1816	This method synthesizes efficient thunking code to call your method from
		1817	the C callback that libev requires. If your compiler can inline your
		1818	callback (i.e. it is visible to it at the place of the C<set> call and
		1819	your compiler is good :), then the method will be fully inlined into the
		1820	thunking function, making it as fast as a direct C callback.
		1821
		1822	Example: simple class declaration and watcher initialisation
		1823
		1824	struct myclass
		1825	{
		1826	void io_cb (ev::io &w, int revents) { }
		1827	}
		1828
		1829	myclass obj;
		1830	ev::io iow;
		1831	iow.set <myclass, &myclass::io_cb> (&obj);
		1832
		1833	=item w->set (void (function)(watcher &w, int), void data = 0)
		1834
		1835	Also sets a callback, but uses a static method or plain function as
		1836	callback. The optional C<data> argument will be stored in the watcher's
		1837	C<data> member and is free for you to use.
		1838
		1839	See the method-C<set> above for more details.
1367		1840
1368	=item w->set (struct ev_loop *)	1841	=item w->set (struct ev_loop *)
1369		1842
1370	Associates a different C<struct ev_loop> with this watcher. You can only	1843	Associates a different C<struct ev_loop> with this watcher. You can only
1371	do this when the watcher is inactive (and not pending either).	1844	do this when the watcher is inactive (and not pending either).
1372		1845
1373	=item w->set ([args])	1846	=item w->set ([args])
1374		1847
1375	Basically the same as C<ev_TYPE_set>, with the same args. Must be	1848	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1376	called at least once. Unlike the C counterpart, an active watcher gets	1849	called at least once. Unlike the C counterpart, an active watcher gets
1377	automatically stopped and restarted.	1850	automatically stopped and restarted when reconfiguring it with this
		1851	method.
1378		1852
1379	=item w->start ()	1853	=item w->start ()
1380		1854
1381	Starts the watcher. Note that there is no C<loop> argument as the	1855	Starts the watcher. Note that there is no C<loop> argument, as the
1382	constructor already takes the loop.	1856	constructor already stores the event loop.
1383		1857
1384	=item w->stop ()	1858	=item w->stop ()
1385		1859
1386	Stops the watcher if it is active. Again, no C<loop> argument.	1860	Stops the watcher if it is active. Again, no C<loop> argument.
1387		1861
…		…
1392		1866
1393	=item w->sweep () C<ev::embed> only	1867	=item w->sweep () C<ev::embed> only
1394		1868
1395	Invokes C<ev_embed_sweep>.	1869	Invokes C<ev_embed_sweep>.
1396		1870
		1871	=item w->update () C<ev::stat> only
		1872
		1873	Invokes C<ev_stat_stat>.
		1874
1397	=back	1875	=back
1398		1876
1399	=back	1877	=back
1400		1878
1401	Example: Define a class with an IO and idle watcher, start one of them in	1879	Example: Define a class with an IO and idle watcher, start one of them in
…		…
1408		1886
1409	myclass ();	1887	myclass ();
1410	}	1888	}
1411		1889
1412	myclass::myclass (int fd)	1890	myclass::myclass (int fd)
1413	: io (this, &myclass::io_cb),
1414	idle (this, &myclass::idle_cb)
1415	{	1891	{
		1892	io .set <myclass, &myclass::io_cb > (this);
		1893	idle.set <myclass, &myclass::idle_cb> (this);
		1894
1416	io.start (fd, ev::READ);	1895	io.start (fd, ev::READ);
1417	}	1896	}
		1897
		1898
		1899	=head1 MACRO MAGIC
		1900
		1901	Libev can be compiled with a variety of options, the most fundemantal is
		1902	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
		1903	callbacks have an initial C<struct ev_loop *> argument.
		1904
		1905	To make it easier to write programs that cope with either variant, the
		1906	following macros are defined:
		1907
		1908	=over 4
		1909
		1910	=item C<EV_A>, C<EV_A_>
		1911
		1912	This provides the loop I<argument> for functions, if one is required ("ev
		1913	loop argument"). The C<EV_A> form is used when this is the sole argument,
		1914	C<EV_A_> is used when other arguments are following. Example:
		1915
		1916	ev_unref (EV_A);
		1917	ev_timer_add (EV_A_ watcher);
		1918	ev_loop (EV_A_ 0);
		1919
		1920	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		1921	which is often provided by the following macro.
		1922
		1923	=item C<EV_P>, C<EV_P_>
		1924
		1925	This provides the loop I<parameter> for functions, if one is required ("ev
		1926	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		1927	C<EV_P_> is used when other parameters are following. Example:
		1928
		1929	// this is how ev_unref is being declared
		1930	static void ev_unref (EV_P);
		1931
		1932	// this is how you can declare your typical callback
		1933	static void cb (EV_P_ ev_timer *w, int revents)
		1934
		1935	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		1936	suitable for use with C<EV_A>.
		1937
		1938	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		1939
		1940	Similar to the other two macros, this gives you the value of the default
		1941	loop, if multiple loops are supported ("ev loop default").
		1942
		1943	=back
		1944
		1945	Example: Declare and initialise a check watcher, utilising the above
		1946	macros so it will work regardless of whether multiple loops are supported
		1947	or not.
		1948
		1949	static void
		1950	check_cb (EV_P_ ev_timer *w, int revents)
		1951	{
		1952	ev_check_stop (EV_A_ w);
		1953	}
		1954
		1955	ev_check check;
		1956	ev_check_init (&check, check_cb);
		1957	ev_check_start (EV_DEFAULT_ &check);
		1958	ev_loop (EV_DEFAULT_ 0);
1418		1959
1419	=head1 EMBEDDING	1960	=head1 EMBEDDING
1420		1961
1421	Libev can (and often is) directly embedded into host	1962	Libev can (and often is) directly embedded into host
1422	applications. Examples of applications that embed it include the Deliantra	1963	applications. Examples of applications that embed it include the Deliantra
…		…
1462	ev_vars.h	2003	ev_vars.h
1463	ev_wrap.h	2004	ev_wrap.h
1464		2005
1465	ev_win32.c required on win32 platforms only	2006	ev_win32.c required on win32 platforms only
1466		2007
1467	ev_select.c only when select backend is enabled (which is is by default)	2008	ev_select.c only when select backend is enabled (which is enabled by default)
1468	ev_poll.c only when poll backend is enabled (disabled by default)	2009	ev_poll.c only when poll backend is enabled (disabled by default)
1469	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2010	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1470	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2011	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1471	ev_port.c only when the solaris port backend is enabled (disabled by default)	2012	ev_port.c only when the solaris port backend is enabled (disabled by default)
1472		2013
1473	F<ev.c> includes the backend files directly when enabled, so you only need	2014	F<ev.c> includes the backend files directly when enabled, so you only need
1474	to compile a single file.	2015	to compile this single file.
1475		2016
1476	=head3 LIBEVENT COMPATIBILITY API	2017	=head3 LIBEVENT COMPATIBILITY API
1477		2018
1478	To include the libevent compatibility API, also include:	2019	To include the libevent compatibility API, also include:
1479		2020
…		…
1492		2033
1493	=head3 AUTOCONF SUPPORT	2034	=head3 AUTOCONF SUPPORT
1494		2035
1495	Instead of using C<EV_STANDALONE=1> and providing your config in	2036	Instead of using C<EV_STANDALONE=1> and providing your config in
1496	whatever way you want, you can also C<m4_include([libev.m4])> in your	2037	whatever way you want, you can also C<m4_include([libev.m4])> in your
1497	F<configure.ac> and leave C<EV_STANDALONE> off. F<ev.c> will then include	2038	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
1498	F<config.h> and configure itself accordingly.	2039	include F<config.h> and configure itself accordingly.
1499		2040
1500	For this of course you need the m4 file:	2041	For this of course you need the m4 file:
1501		2042
1502	libev.m4	2043	libev.m4
1503		2044
…		…
1597		2138
1598	=item EV_USE_DEVPOLL	2139	=item EV_USE_DEVPOLL
1599		2140
1600	reserved for future expansion, works like the USE symbols above.	2141	reserved for future expansion, works like the USE symbols above.
1601		2142
		2143	=item EV_USE_INOTIFY
		2144
		2145	If defined to be C<1>, libev will compile in support for the Linux inotify
		2146	interface to speed up C<ev_stat> watchers. Its actual availability will
		2147	be detected at runtime.
		2148
1602	=item EV_H	2149	=item EV_H
1603		2150
1604	The name of the F<ev.h> header file used to include it. The default if	2151	The name of the F<ev.h> header file used to include it. The default if
1605	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2152	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
1606	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2153	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
1629	will have the C<struct ev_loop *> as first argument, and you can create	2176	will have the C<struct ev_loop *> as first argument, and you can create
1630	additional independent event loops. Otherwise there will be no support	2177	additional independent event loops. Otherwise there will be no support
1631	for multiple event loops and there is no first event loop pointer	2178	for multiple event loops and there is no first event loop pointer
1632	argument. Instead, all functions act on the single default loop.	2179	argument. Instead, all functions act on the single default loop.
1633		2180
		2181	=item EV_MINPRI
		2182
		2183	=item EV_MAXPRI
		2184
		2185	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2186	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2187	provide for more priorities by overriding those symbols (usually defined
		2188	to be C<-2> and C<2>, respectively).
		2189
		2190	When doing priority-based operations, libev usually has to linearly search
		2191	all the priorities, so having many of them (hundreds) uses a lot of space
		2192	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2193	fine.
		2194
		2195	If your embedding app does not need any priorities, defining these both to
		2196	C<0> will save some memory and cpu.
		2197
1634	=item EV_PERIODICS	2198	=item EV_PERIODIC_ENABLE
1635		2199
1636	If undefined or defined to be C<1>, then periodic timers are supported,	2200	If undefined or defined to be C<1>, then periodic timers are supported. If
1637	otherwise not. This saves a few kb of code.	2201	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2202	code.
		2203
		2204	=item EV_IDLE_ENABLE
		2205
		2206	If undefined or defined to be C<1>, then idle watchers are supported. If
		2207	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2208	code.
		2209
		2210	=item EV_EMBED_ENABLE
		2211
		2212	If undefined or defined to be C<1>, then embed watchers are supported. If
		2213	defined to be C<0>, then they are not.
		2214
		2215	=item EV_STAT_ENABLE
		2216
		2217	If undefined or defined to be C<1>, then stat watchers are supported. If
		2218	defined to be C<0>, then they are not.
		2219
		2220	=item EV_FORK_ENABLE
		2221
		2222	If undefined or defined to be C<1>, then fork watchers are supported. If
		2223	defined to be C<0>, then they are not.
		2224
		2225	=item EV_MINIMAL
		2226
		2227	If you need to shave off some kilobytes of code at the expense of some
		2228	speed, define this symbol to C<1>. Currently only used for gcc to override
		2229	some inlining decisions, saves roughly 30% codesize of amd64.
		2230
		2231	=item EV_PID_HASHSIZE
		2232
		2233	C<ev_child> watchers use a small hash table to distribute workload by
		2234	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2235	than enough. If you need to manage thousands of children you might want to
		2236	increase this value (I<must> be a power of two).
		2237
		2238	=item EV_INOTIFY_HASHSIZE
		2239
		2240	C<ev_staz> watchers use a small hash table to distribute workload by
		2241	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2242	usually more than enough. If you need to manage thousands of C<ev_stat>
		2243	watchers you might want to increase this value (I<must> be a power of
		2244	two).
1638		2245
1639	=item EV_COMMON	2246	=item EV_COMMON
1640		2247
1641	By default, all watchers have a C<void *data> member. By redefining	2248	By default, all watchers have a C<void *data> member. By redefining
1642	this macro to a something else you can include more and other types of	2249	this macro to a something else you can include more and other types of
…		…
1647		2254
1648	#define EV_COMMON \	2255	#define EV_COMMON \
1649	SV self; / contains this struct */ \	2256	SV self; / contains this struct */ \
1650	SV cb_sv, fh /* note no trailing ";" */	2257	SV cb_sv, fh /* note no trailing ";" */
1651		2258
1652	=item EV_CB_DECLARE(type)	2259	=item EV_CB_DECLARE (type)
1653		2260
1654	=item EV_CB_INVOKE(watcher,revents)	2261	=item EV_CB_INVOKE (watcher, revents)
1655		2262
1656	=item ev_set_cb(ev,cb)	2263	=item ev_set_cb (ev, cb)
1657		2264
1658	Can be used to change the callback member declaration in each watcher,	2265	Can be used to change the callback member declaration in each watcher,
1659	and the way callbacks are invoked and set. Must expand to a struct member	2266	and the way callbacks are invoked and set. Must expand to a struct member
1660	definition and a statement, respectively. See the F<ev.v> header file for	2267	definition and a statement, respectively. See the F<ev.v> header file for
1661	their default definitions. One possible use for overriding these is to	2268	their default definitions. One possible use for overriding these is to
1662	avoid the ev_loop pointer as first argument in all cases, or to use method	2269	avoid the C<struct ev_loop *> as first argument in all cases, or to use
1663	calls instead of plain function calls in C++.	2270	method calls instead of plain function calls in C++.
1664		2271
1665	=head2 EXAMPLES	2272	=head2 EXAMPLES
1666		2273
1667	For a real-world example of a program the includes libev	2274	For a real-world example of a program the includes libev
1668	verbatim, you can have a look at the EV perl module	2275	verbatim, you can have a look at the EV perl module
…		…
1671	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2278	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
1672	will be compiled. It is pretty complex because it provides its own header	2279	will be compiled. It is pretty complex because it provides its own header
1673	file.	2280	file.
1674		2281
1675	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2282	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
1676	that everybody includes and which overrides some autoconf choices:	2283	that everybody includes and which overrides some configure choices:
1677		2284
		2285	#define EV_MINIMAL 1
1678	#define EV_USE_POLL 0	2286	#define EV_USE_POLL 0
1679	#define EV_MULTIPLICITY 0	2287	#define EV_MULTIPLICITY 0
1680	#define EV_PERIODICS 0	2288	#define EV_PERIODIC_ENABLE 0
		2289	#define EV_STAT_ENABLE 0
		2290	#define EV_FORK_ENABLE 0
1681	#define EV_CONFIG_H <config.h>	2291	#define EV_CONFIG_H <config.h>
		2292	#define EV_MINPRI 0
		2293	#define EV_MAXPRI 0
1682		2294
1683	#include "ev++.h"	2295	#include "ev++.h"
1684		2296
1685	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2297	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
1686		2298
1687	#include "ev_cpp.h"	2299	#include "ev_cpp.h"
1688	#include "ev.c"	2300	#include "ev.c"
1689		2301
		2302
		2303	=head1 COMPLEXITIES
		2304
		2305	In this section the complexities of (many of) the algorithms used inside
		2306	libev will be explained. For complexity discussions about backends see the
		2307	documentation for C<ev_default_init>.
		2308
		2309	All of the following are about amortised time: If an array needs to be
		2310	extended, libev needs to realloc and move the whole array, but this
		2311	happens asymptotically never with higher number of elements, so O(1) might
		2312	mean it might do a lengthy realloc operation in rare cases, but on average
		2313	it is much faster and asymptotically approaches constant time.
		2314
		2315	=over 4
		2316
		2317	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
		2318
		2319	This means that, when you have a watcher that triggers in one hour and
		2320	there are 100 watchers that would trigger before that then inserting will
		2321	have to skip those 100 watchers.
		2322
		2323	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
		2324
		2325	That means that for changing a timer costs less than removing/adding them
		2326	as only the relative motion in the event queue has to be paid for.
		2327
		2328	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
		2329
		2330	These just add the watcher into an array or at the head of a list.
		2331	=item Stopping check/prepare/idle watchers: O(1)
		2332
		2333	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2334
		2335	These watchers are stored in lists then need to be walked to find the
		2336	correct watcher to remove. The lists are usually short (you don't usually
		2337	have many watchers waiting for the same fd or signal).
		2338
		2339	=item Finding the next timer per loop iteration: O(1)
		2340
		2341	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
		2342
		2343	A change means an I/O watcher gets started or stopped, which requires
		2344	libev to recalculate its status (and possibly tell the kernel).
		2345
		2346	=item Activating one watcher: O(1)
		2347
		2348	=item Priority handling: O(number_of_priorities)
		2349
		2350	Priorities are implemented by allocating some space for each
		2351	priority. When doing priority-based operations, libev usually has to
		2352	linearly search all the priorities.
		2353
		2354	=back
		2355
		2356
1690	=head1 AUTHOR	2357	=head1 AUTHOR
1691		2358
1692	Marc Lehmann <libev@schmorp.de>.	2359	Marc Lehmann <libev@schmorp.de>.
1693		2360

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Comparing libev/ev.pod (file contents): Revision 1.41 by root, Sat Nov 24 10:19:14 2007 UTC vs. Revision 1.72 by root, Fri Dec 7 20:19:16 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.41 by root, Sat Nov 24 10:19:14 2007 UTC vs.
Revision 1.72 by root, Fri Dec 7 20:19:16 2007 UTC