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

Comparing libev/ev.pod (file contents):
Revision 1.52 by root, Tue Nov 27 19:41:52 2007 UTC vs.
Revision 1.83 by root, Wed Dec 12 17:55:31 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
…		…
65		117
66	=item int ev_version_major ()	118	=item int ev_version_major ()
67		119
68	=item int ev_version_minor ()	120	=item int ev_version_minor ()
69		121
70	You can find out the major and minor version numbers of the library	122	You can find out the major and minor ABI version numbers of the library
71	you linked against by calling the functions C<ev_version_major> and	123	you linked against by calling the functions C<ev_version_major> and
72	C<ev_version_minor>. If you want, you can compare against the global	124	C<ev_version_minor>. If you want, you can compare against the global
73	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the	125	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
74	version of the library your program was compiled against.	126	version of the library your program was compiled against.
75		127
		128	These version numbers refer to the ABI version of the library, not the
		129	release version.
		130
76	Usually, it's a good idea to terminate if the major versions mismatch,	131	Usually, it's a good idea to terminate if the major versions mismatch,
77	as this indicates an incompatible change. Minor versions are usually	132	as this indicates an incompatible change. Minor versions are usually
78	compatible to older versions, so a larger minor version alone is usually	133	compatible to older versions, so a larger minor version alone is usually
79	not a problem.	134	not a problem.
80		135
81	Example: make sure we haven't accidentally been linked against the wrong	136	Example: Make sure we haven't accidentally been linked against the wrong
82	version:	137	version.
83		138
84	assert (("libev version mismatch",	139	assert (("libev version mismatch",
85	ev_version_major () == EV_VERSION_MAJOR	140	ev_version_major () == EV_VERSION_MAJOR
86	&& ev_version_minor () >= EV_VERSION_MINOR));	141	&& ev_version_minor () >= EV_VERSION_MINOR));
87		142
…		…
115	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	170	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
116	recommended ones.	171	recommended ones.
117		172
118	See the description of C<ev_embed> watchers for more info.	173	See the description of C<ev_embed> watchers for more info.
119		174
120	=item ev_set_allocator (void (cb)(void *ptr, size_t size))	175	=item ev_set_allocator (void (cb)(void *ptr, long size))
121		176
122	Sets the allocation function to use (the prototype and semantics are	177	Sets the allocation function to use (the prototype is similar - the
123	identical to the realloc C function). It is used to allocate and free	178	semantics is identical - to the realloc C function). It is used to
124	memory (no surprises here). If it returns zero when memory needs to be	179	allocate and free memory (no surprises here). If it returns zero when
125	allocated, the library might abort or take some potentially destructive	180	memory needs to be allocated, the library might abort or take some
126	action. The default is your system realloc function.	181	potentially destructive action. The default is your system realloc
		182	function.
127		183
128	You could override this function in high-availability programs to, say,	184	You could override this function in high-availability programs to, say,
129	free some memory if it cannot allocate memory, to use a special allocator,	185	free some memory if it cannot allocate memory, to use a special allocator,
130	or even to sleep a while and retry until some memory is available.	186	or even to sleep a while and retry until some memory is available.
131		187
132	Example: replace the libev allocator with one that waits a bit and then	188	Example: Replace the libev allocator with one that waits a bit and then
133	retries: better than mine).	189	retries).
134		190
135	static void *	191	static void *
136	persistent_realloc (void *ptr, size_t size)	192	persistent_realloc (void *ptr, size_t size)
137	{	193	{
138	for (;;)	194	for (;;)
…		…
157	callback is set, then libev will expect it to remedy the sitution, no	213	callback is set, then libev will expect it to remedy the sitution, no
158	matter what, when it returns. That is, libev will generally retry the	214	matter what, when it returns. That is, libev will generally retry the
159	requested operation, or, if the condition doesn't go away, do bad stuff	215	requested operation, or, if the condition doesn't go away, do bad stuff
160	(such as abort).	216	(such as abort).
161		217
162	Example: do the same thing as libev does internally:	218	Example: This is basically the same thing that libev does internally, too.
163		219
164	static void	220	static void
165	fatal_error (const char *msg)	221	fatal_error (const char *msg)
166	{	222	{
167	perror (msg);	223	perror (msg);
…		…
217	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	273	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
218	override the flags completely if it is found in the environment. This is	274	override the flags completely if it is found in the environment. This is
219	useful to try out specific backends to test their performance, or to work	275	useful to try out specific backends to test their performance, or to work
220	around bugs.	276	around bugs.
221		277
		278	=item C<EVFLAG_FORKCHECK>
		279
		280	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		281	a fork, you can also make libev check for a fork in each iteration by
		282	enabling this flag.
		283
		284	This works by calling C<getpid ()> on every iteration of the loop,
		285	and thus this might slow down your event loop if you do a lot of loop
		286	iterations and little real work, but is usually not noticeable (on my
		287	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		288	without a syscall and thus I<very> fast, but my Linux system also has
		289	C<pthread_atfork> which is even faster).
		290
		291	The big advantage of this flag is that you can forget about fork (and
		292	forget about forgetting to tell libev about forking) when you use this
		293	flag.
		294
		295	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		296	environment variable.
		297
222	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	298	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
223		299
224	This is your standard select(2) backend. Not I<completely> standard, as	300	This is your standard select(2) backend. Not I<completely> standard, as
225	libev tries to roll its own fd_set with no limits on the number of fds,	301	libev tries to roll its own fd_set with no limits on the number of fds,
226	but if that fails, expect a fairly low limit on the number of fds when	302	but if that fails, expect a fairly low limit on the number of fds when
…		…
313	Similar to C<ev_default_loop>, but always creates a new event loop that is	389	Similar to C<ev_default_loop>, but always creates a new event loop that is
314	always distinct from the default loop. Unlike the default loop, it cannot	390	always distinct from the default loop. Unlike the default loop, it cannot
315	handle signal and child watchers, and attempts to do so will be greeted by	391	handle signal and child watchers, and attempts to do so will be greeted by
316	undefined behaviour (or a failed assertion if assertions are enabled).	392	undefined behaviour (or a failed assertion if assertions are enabled).
317		393
318	Example: try to create a event loop that uses epoll and nothing else.	394	Example: Try to create a event loop that uses epoll and nothing else.
319		395
320	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	396	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
321	if (!epoller)	397	if (!epoller)
322	fatal ("no epoll found here, maybe it hides under your chair");	398	fatal ("no epoll found here, maybe it hides under your chair");
323		399
…		…
361		437
362	Like C<ev_default_fork>, but acts on an event loop created by	438	Like C<ev_default_fork>, but acts on an event loop created by
363	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	439	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
364	after fork, and how you do this is entirely your own problem.	440	after fork, and how you do this is entirely your own problem.
365		441
		442	=item unsigned int ev_loop_count (loop)
		443
		444	Returns the count of loop iterations for the loop, which is identical to
		445	the number of times libev did poll for new events. It starts at C<0> and
		446	happily wraps around with enough iterations.
		447
		448	This value can sometimes be useful as a generation counter of sorts (it
		449	"ticks" the number of loop iterations), as it roughly corresponds with
		450	C<ev_prepare> and C<ev_check> calls.
		451
366	=item unsigned int ev_backend (loop)	452	=item unsigned int ev_backend (loop)
367		453
368	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	454	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
369	use.	455	use.
370		456
…		…
403	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	489	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
404	usually a better approach for this kind of thing.	490	usually a better approach for this kind of thing.
405		491
406	Here are the gory details of what C<ev_loop> does:	492	Here are the gory details of what C<ev_loop> does:
407		493
		494	- Before the first iteration, call any pending watchers.
408	* If there are no active watchers (reference count is zero), return.	495	* If there are no active watchers (reference count is zero), return.
409	- Queue prepare watchers and then call all outstanding watchers.	496	- Queue all prepare watchers and then call all outstanding watchers.
410	- If we have been forked, recreate the kernel state.	497	- If we have been forked, recreate the kernel state.
411	- Update the kernel state with all outstanding changes.	498	- Update the kernel state with all outstanding changes.
412	- Update the "event loop time".	499	- Update the "event loop time".
413	- Calculate for how long to block.	500	- Calculate for how long to block.
414	- Block the process, waiting for any events.	501	- Block the process, waiting for any events.
…		…
422	Signals and child watchers are implemented as I/O watchers, and will	509	Signals and child watchers are implemented as I/O watchers, and will
423	be handled here by queueing them when their watcher gets executed.	510	be handled here by queueing them when their watcher gets executed.
424	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	511	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
425	were used, return, otherwise continue with step *.	512	were used, return, otherwise continue with step *.
426		513
427	Example: queue some jobs and then loop until no events are outsanding	514	Example: Queue some jobs and then loop until no events are outsanding
428	anymore.	515	anymore.
429		516
430	... queue jobs here, make sure they register event watchers as long	517	... queue jobs here, make sure they register event watchers as long
431	... as they still have work to do (even an idle watcher will do..)	518	... as they still have work to do (even an idle watcher will do..)
432	ev_loop (my_loop, 0);	519	ev_loop (my_loop, 0);
…		…
452	visible to the libev user and should not keep C<ev_loop> from exiting if	539	visible to the libev user and should not keep C<ev_loop> from exiting if
453	no event watchers registered by it are active. It is also an excellent	540	no event watchers registered by it are active. It is also an excellent
454	way to do this for generic recurring timers or from within third-party	541	way to do this for generic recurring timers or from within third-party
455	libraries. Just remember to I<unref after start> and I<ref before stop>.	542	libraries. Just remember to I<unref after start> and I<ref before stop>.
456		543
457	Example: create a signal watcher, but keep it from keeping C<ev_loop>	544	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
458	running when nothing else is active.	545	running when nothing else is active.
459		546
460	struct dv_signal exitsig;	547	struct ev_signal exitsig;
461	ev_signal_init (&exitsig, sig_cb, SIGINT);	548	ev_signal_init (&exitsig, sig_cb, SIGINT);
462	ev_signal_start (myloop, &exitsig);	549	ev_signal_start (loop, &exitsig);
463	evf_unref (myloop);	550	evf_unref (loop);
464		551
465	Example: for some weird reason, unregister the above signal handler again.	552	Example: For some weird reason, unregister the above signal handler again.
466		553
467	ev_ref (myloop);	554	ev_ref (loop);
468	ev_signal_stop (myloop, &exitsig);	555	ev_signal_stop (loop, &exitsig);
469		556
470	=back	557	=back
471		558
472		559
473	=head1 ANATOMY OF A WATCHER	560	=head1 ANATOMY OF A WATCHER
…		…
653	=item bool ev_is_pending (ev_TYPE *watcher)	740	=item bool ev_is_pending (ev_TYPE *watcher)
654		741
655	Returns a true value iff the watcher is pending, (i.e. it has outstanding	742	Returns a true value iff the watcher is pending, (i.e. it has outstanding
656	events but its callback has not yet been invoked). As long as a watcher	743	events but its callback has not yet been invoked). As long as a watcher
657	is pending (but not active) you must not call an init function on it (but	744	is pending (but not active) you must not call an init function on it (but
658	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	745	C<ev_TYPE_set> is safe), you must not change its priority, and you must
659	libev (e.g. you cnanot C<free ()> it).	746	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		747	it).
660		748
661	=item callback = ev_cb (ev_TYPE *watcher)	749	=item callback ev_cb (ev_TYPE *watcher)
662		750
663	Returns the callback currently set on the watcher.	751	Returns the callback currently set on the watcher.
664		752
665	=item ev_cb_set (ev_TYPE *watcher, callback)	753	=item ev_cb_set (ev_TYPE *watcher, callback)
666		754
667	Change the callback. You can change the callback at virtually any time	755	Change the callback. You can change the callback at virtually any time
668	(modulo threads).	756	(modulo threads).
		757
		758	=item ev_set_priority (ev_TYPE *watcher, priority)
		759
		760	=item int ev_priority (ev_TYPE *watcher)
		761
		762	Set and query the priority of the watcher. The priority is a small
		763	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		764	(default: C<-2>). Pending watchers with higher priority will be invoked
		765	before watchers with lower priority, but priority will not keep watchers
		766	from being executed (except for C<ev_idle> watchers).
		767
		768	This means that priorities are I<only> used for ordering callback
		769	invocation after new events have been received. This is useful, for
		770	example, to reduce latency after idling, or more often, to bind two
		771	watchers on the same event and make sure one is called first.
		772
		773	If you need to suppress invocation when higher priority events are pending
		774	you need to look at C<ev_idle> watchers, which provide this functionality.
		775
		776	You I<must not> change the priority of a watcher as long as it is active or
		777	pending.
		778
		779	The default priority used by watchers when no priority has been set is
		780	always C<0>, which is supposed to not be too high and not be too low :).
		781
		782	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		783	fine, as long as you do not mind that the priority value you query might
		784	or might not have been adjusted to be within valid range.
		785
		786	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		787
		788	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		789	C<loop> nor C<revents> need to be valid as long as the watcher callback
		790	can deal with that fact.
		791
		792	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		793
		794	If the watcher is pending, this function returns clears its pending status
		795	and returns its C<revents> bitset (as if its callback was invoked). If the
		796	watcher isn't pending it does nothing and returns C<0>.
669		797
670	=back	798	=back
671		799
672		800
673	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	801	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
694	{	822	{
695	struct my_io w = (struct my_io )w_;	823	struct my_io w = (struct my_io )w_;
696	...	824	...
697	}	825	}
698		826
699	More interesting and less C-conformant ways of catsing your callback type	827	More interesting and less C-conformant ways of casting your callback type
700	have been omitted....	828	instead have been omitted.
		829
		830	Another common scenario is having some data structure with multiple
		831	watchers:
		832
		833	struct my_biggy
		834	{
		835	int some_data;
		836	ev_timer t1;
		837	ev_timer t2;
		838	}
		839
		840	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		841	you need to use C<offsetof>:
		842
		843	#include <stddef.h>
		844
		845	static void
		846	t1_cb (EV_P_ struct ev_timer *w, int revents)
		847	{
		848	struct my_biggy big = (struct my_biggy *
		849	(((char *)w) - offsetof (struct my_biggy, t1));
		850	}
		851
		852	static void
		853	t2_cb (EV_P_ struct ev_timer *w, int revents)
		854	{
		855	struct my_biggy big = (struct my_biggy *
		856	(((char *)w) - offsetof (struct my_biggy, t2));
		857	}
701		858
702		859
703	=head1 WATCHER TYPES	860	=head1 WATCHER TYPES
704		861
705	This section describes each watcher in detail, but will not repeat	862	This section describes each watcher in detail, but will not repeat
…		…
750	it is best to always use non-blocking I/O: An extra C<read>(2) returning	907	it is best to always use non-blocking I/O: An extra C<read>(2) returning
751	C<EAGAIN> is far preferable to a program hanging until some data arrives.	908	C<EAGAIN> is far preferable to a program hanging until some data arrives.
752		909
753	If you cannot run the fd in non-blocking mode (for example you should not	910	If you cannot run the fd in non-blocking mode (for example you should not
754	play around with an Xlib connection), then you have to seperately re-test	911	play around with an Xlib connection), then you have to seperately re-test
755	wether a file descriptor is really ready with a known-to-be good interface	912	whether a file descriptor is really ready with a known-to-be good interface
756	such as poll (fortunately in our Xlib example, Xlib already does this on	913	such as poll (fortunately in our Xlib example, Xlib already does this on
757	its own, so its quite safe to use).	914	its own, so its quite safe to use).
		915
		916	=head3 The special problem of disappearing file descriptors
		917
		918	Some backends (e.g kqueue, epoll) need to be told about closing a file
		919	descriptor (either by calling C<close> explicitly or by any other means,
		920	such as C<dup>). The reason is that you register interest in some file
		921	descriptor, but when it goes away, the operating system will silently drop
		922	this interest. If another file descriptor with the same number then is
		923	registered with libev, there is no efficient way to see that this is, in
		924	fact, a different file descriptor.
		925
		926	To avoid having to explicitly tell libev about such cases, libev follows
		927	the following policy: Each time C<ev_io_set> is being called, libev
		928	will assume that this is potentially a new file descriptor, otherwise
		929	it is assumed that the file descriptor stays the same. That means that
		930	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		931	descriptor even if the file descriptor number itself did not change.
		932
		933	This is how one would do it normally anyway, the important point is that
		934	the libev application should not optimise around libev but should leave
		935	optimisations to libev.
		936
		937
		938	=head3 Watcher-Specific Functions
758		939
759	=over 4	940	=over 4
760		941
761	=item ev_io_init (ev_io *, callback, int fd, int events)	942	=item ev_io_init (ev_io *, callback, int fd, int events)
762		943
…		…
774		955
775	The events being watched.	956	The events being watched.
776		957
777	=back	958	=back
778		959
779	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	960	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
780	readable, but only once. Since it is likely line-buffered, you could	961	readable, but only once. Since it is likely line-buffered, you could
781	attempt to read a whole line in the callback:	962	attempt to read a whole line in the callback.
782		963
783	static void	964	static void
784	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	965	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
785	{	966	{
786	ev_io_stop (loop, w);	967	ev_io_stop (loop, w);
…		…
816		997
817	The callback is guarenteed to be invoked only when its timeout has passed,	998	The callback is guarenteed to be invoked only when its timeout has passed,
818	but if multiple timers become ready during the same loop iteration then	999	but if multiple timers become ready during the same loop iteration then
819	order of execution is undefined.	1000	order of execution is undefined.
820		1001
		1002	=head3 Watcher-Specific Functions and Data Members
		1003
821	=over 4	1004	=over 4
822		1005
823	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1006	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
824		1007
825	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1008	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
838	=item ev_timer_again (loop)	1021	=item ev_timer_again (loop)
839		1022
840	This will act as if the timer timed out and restart it again if it is	1023	This will act as if the timer timed out and restart it again if it is
841	repeating. The exact semantics are:	1024	repeating. The exact semantics are:
842		1025
		1026	If the timer is pending, its pending status is cleared.
		1027
843	If the timer is started but nonrepeating, stop it.	1028	If the timer is started but nonrepeating, stop it (as if it timed out).
844		1029
845	If the timer is repeating, either start it if necessary (with the repeat	1030	If the timer is repeating, either start it if necessary (with the
846	value), or reset the running timer to the repeat value.	1031	C<repeat> value), or reset the running timer to the C<repeat> value.
847		1032
848	This sounds a bit complicated, but here is a useful and typical	1033	This sounds a bit complicated, but here is a useful and typical
849	example: Imagine you have a tcp connection and you want a so-called	1034	example: Imagine you have a tcp connection and you want a so-called idle
850	idle timeout, that is, you want to be called when there have been,	1035	timeout, that is, you want to be called when there have been, say, 60
851	say, 60 seconds of inactivity on the socket. The easiest way to do	1036	seconds of inactivity on the socket. The easiest way to do this is to
852	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling	1037	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
853	C<ev_timer_again> each time you successfully read or write some data. If	1038	C<ev_timer_again> each time you successfully read or write some data. If
854	you go into an idle state where you do not expect data to travel on the	1039	you go into an idle state where you do not expect data to travel on the
855	socket, you can stop the timer, and again will automatically restart it if	1040	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
856	need be.	1041	automatically restart it if need be.
857		1042
858	You can also ignore the C<after> value and C<ev_timer_start> altogether	1043	That means you can ignore the C<after> value and C<ev_timer_start>
859	and only ever use the C<repeat> value:	1044	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
860		1045
861	ev_timer_init (timer, callback, 0., 5.);	1046	ev_timer_init (timer, callback, 0., 5.);
862	ev_timer_again (loop, timer);	1047	ev_timer_again (loop, timer);
863	...	1048	...
864	timer->again = 17.;	1049	timer->again = 17.;
865	ev_timer_again (loop, timer);	1050	ev_timer_again (loop, timer);
866	...	1051	...
867	timer->again = 10.;	1052	timer->again = 10.;
868	ev_timer_again (loop, timer);	1053	ev_timer_again (loop, timer);
869		1054
870	This is more efficient then stopping/starting the timer eahc time you want	1055	This is more slightly efficient then stopping/starting the timer each time
871	to modify its timeout value.	1056	you want to modify its timeout value.
872		1057
873	=item ev_tstamp repeat [read-write]	1058	=item ev_tstamp repeat [read-write]
874		1059
875	The current C<repeat> value. Will be used each time the watcher times out	1060	The current C<repeat> value. Will be used each time the watcher times out
876	or C<ev_timer_again> is called and determines the next timeout (if any),	1061	or C<ev_timer_again> is called and determines the next timeout (if any),
877	which is also when any modifications are taken into account.	1062	which is also when any modifications are taken into account.
878		1063
879	=back	1064	=back
880		1065
881	Example: create a timer that fires after 60 seconds.	1066	Example: Create a timer that fires after 60 seconds.
882		1067
883	static void	1068	static void
884	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	1069	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
885	{	1070	{
886	.. one minute over, w is actually stopped right here	1071	.. one minute over, w is actually stopped right here
…		…
888		1073
889	struct ev_timer mytimer;	1074	struct ev_timer mytimer;
890	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1075	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
891	ev_timer_start (loop, &mytimer);	1076	ev_timer_start (loop, &mytimer);
892		1077
893	Example: create a timeout timer that times out after 10 seconds of	1078	Example: Create a timeout timer that times out after 10 seconds of
894	inactivity.	1079	inactivity.
895		1080
896	static void	1081	static void
897	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1082	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
898	{	1083	{
…		…
918	but on wallclock time (absolute time). You can tell a periodic watcher	1103	but on wallclock time (absolute time). You can tell a periodic watcher
919	to trigger "at" some specific point in time. For example, if you tell a	1104	to trigger "at" some specific point in time. For example, if you tell a
920	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1105	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
921	+ 10.>) and then reset your system clock to the last year, then it will	1106	+ 10.>) and then reset your system clock to the last year, then it will
922	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1107	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
923	roughly 10 seconds later and of course not if you reset your system time	1108	roughly 10 seconds later).
924	again).
925		1109
926	They can also be used to implement vastly more complex timers, such as	1110	They can also be used to implement vastly more complex timers, such as
927	triggering an event on eahc midnight, local time.	1111	triggering an event on each midnight, local time or other, complicated,
		1112	rules.
928		1113
929	As with timers, the callback is guarenteed to be invoked only when the	1114	As with timers, the callback is guarenteed to be invoked only when the
930	time (C<at>) has been passed, but if multiple periodic timers become ready	1115	time (C<at>) has been passed, but if multiple periodic timers become ready
931	during the same loop iteration then order of execution is undefined.	1116	during the same loop iteration then order of execution is undefined.
932		1117
		1118	=head3 Watcher-Specific Functions and Data Members
		1119
933	=over 4	1120	=over 4
934		1121
935	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1122	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
936		1123
937	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1124	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
939	Lots of arguments, lets sort it out... There are basically three modes of	1126	Lots of arguments, lets sort it out... There are basically three modes of
940	operation, and we will explain them from simplest to complex:	1127	operation, and we will explain them from simplest to complex:
941		1128
942	=over 4	1129	=over 4
943		1130
944	=item * absolute timer (interval = reschedule_cb = 0)	1131	=item * absolute timer (at = time, interval = reschedule_cb = 0)
945		1132
946	In this configuration the watcher triggers an event at the wallclock time	1133	In this configuration the watcher triggers an event at the wallclock time
947	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1134	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
948	that is, if it is to be run at January 1st 2011 then it will run when the	1135	that is, if it is to be run at January 1st 2011 then it will run when the
949	system time reaches or surpasses this time.	1136	system time reaches or surpasses this time.
950		1137
951	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1138	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
952		1139
953	In this mode the watcher will always be scheduled to time out at the next	1140	In this mode the watcher will always be scheduled to time out at the next
954	C<at + N * interval> time (for some integer N) and then repeat, regardless	1141	C<at + N * interval> time (for some integer N, which can also be negative)
955	of any time jumps.	1142	and then repeat, regardless of any time jumps.
956		1143
957	This can be used to create timers that do not drift with respect to system	1144	This can be used to create timers that do not drift with respect to system
958	time:	1145	time:
959		1146
960	ev_periodic_set (&periodic, 0., 3600., 0);	1147	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
966		1153
967	Another way to think about it (for the mathematically inclined) is that	1154	Another way to think about it (for the mathematically inclined) is that
968	C<ev_periodic> will try to run the callback in this mode at the next possible	1155	C<ev_periodic> will try to run the callback in this mode at the next possible
969	time where C<time = at (mod interval)>, regardless of any time jumps.	1156	time where C<time = at (mod interval)>, regardless of any time jumps.
970		1157
		1158	For numerical stability it is preferable that the C<at> value is near
		1159	C<ev_now ()> (the current time), but there is no range requirement for
		1160	this value.
		1161
971	=item * manual reschedule mode (reschedule_cb = callback)	1162	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
972		1163
973	In this mode the values for C<interval> and C<at> are both being	1164	In this mode the values for C<interval> and C<at> are both being
974	ignored. Instead, each time the periodic watcher gets scheduled, the	1165	ignored. Instead, each time the periodic watcher gets scheduled, the
975	reschedule callback will be called with the watcher as first, and the	1166	reschedule callback will be called with the watcher as first, and the
976	current time as second argument.	1167	current time as second argument.
977		1168
978	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1169	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
979	ever, or make any event loop modifications>. If you need to stop it,	1170	ever, or make any event loop modifications>. If you need to stop it,
980	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1171	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
981	starting a prepare watcher).	1172	starting an C<ev_prepare> watcher, which is legal).
982		1173
983	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	1174	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
984	ev_tstamp now)>, e.g.:	1175	ev_tstamp now)>, e.g.:
985		1176
986	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1177	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
1009	Simply stops and restarts the periodic watcher again. This is only useful	1200	Simply stops and restarts the periodic watcher again. This is only useful
1010	when you changed some parameters or the reschedule callback would return	1201	when you changed some parameters or the reschedule callback would return
1011	a different time than the last time it was called (e.g. in a crond like	1202	a different time than the last time it was called (e.g. in a crond like
1012	program when the crontabs have changed).	1203	program when the crontabs have changed).
1013		1204
		1205	=item ev_tstamp offset [read-write]
		1206
		1207	When repeating, this contains the offset value, otherwise this is the
		1208	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1209
		1210	Can be modified any time, but changes only take effect when the periodic
		1211	timer fires or C<ev_periodic_again> is being called.
		1212
1014	=item ev_tstamp interval [read-write]	1213	=item ev_tstamp interval [read-write]
1015		1214
1016	The current interval value. Can be modified any time, but changes only	1215	The current interval value. Can be modified any time, but changes only
1017	take effect when the periodic timer fires or C<ev_periodic_again> is being	1216	take effect when the periodic timer fires or C<ev_periodic_again> is being
1018	called.	1217	called.
…		…
1023	switched off. Can be changed any time, but changes only take effect when	1222	switched off. Can be changed any time, but changes only take effect when
1024	the periodic timer fires or C<ev_periodic_again> is being called.	1223	the periodic timer fires or C<ev_periodic_again> is being called.
1025		1224
1026	=back	1225	=back
1027		1226
1028	Example: call a callback every hour, or, more precisely, whenever the	1227	Example: Call a callback every hour, or, more precisely, whenever the
1029	system clock is divisible by 3600. The callback invocation times have	1228	system clock is divisible by 3600. The callback invocation times have
1030	potentially a lot of jittering, but good long-term stability.	1229	potentially a lot of jittering, but good long-term stability.
1031		1230
1032	static void	1231	static void
1033	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1232	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
1037		1236
1038	struct ev_periodic hourly_tick;	1237	struct ev_periodic hourly_tick;
1039	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1238	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1040	ev_periodic_start (loop, &hourly_tick);	1239	ev_periodic_start (loop, &hourly_tick);
1041		1240
1042	Example: the same as above, but use a reschedule callback to do it:	1241	Example: The same as above, but use a reschedule callback to do it:
1043		1242
1044	#include <math.h>	1243	#include <math.h>
1045		1244
1046	static ev_tstamp	1245	static ev_tstamp
1047	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1246	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
1049	return fmod (now, 3600.) + 3600.;	1248	return fmod (now, 3600.) + 3600.;
1050	}	1249	}
1051		1250
1052	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1251	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1053		1252
1054	Example: call a callback every hour, starting now:	1253	Example: Call a callback every hour, starting now:
1055		1254
1056	struct ev_periodic hourly_tick;	1255	struct ev_periodic hourly_tick;
1057	ev_periodic_init (&hourly_tick, clock_cb,	1256	ev_periodic_init (&hourly_tick, clock_cb,
1058	fmod (ev_now (loop), 3600.), 3600., 0);	1257	fmod (ev_now (loop), 3600.), 3600., 0);
1059	ev_periodic_start (loop, &hourly_tick);	1258	ev_periodic_start (loop, &hourly_tick);
…		…
1071	with the kernel (thus it coexists with your own signal handlers as long	1270	with the kernel (thus it coexists with your own signal handlers as long
1072	as you don't register any with libev). Similarly, when the last signal	1271	as you don't register any with libev). Similarly, when the last signal
1073	watcher for a signal is stopped libev will reset the signal handler to	1272	watcher for a signal is stopped libev will reset the signal handler to
1074	SIG_DFL (regardless of what it was set to before).	1273	SIG_DFL (regardless of what it was set to before).
1075		1274
		1275	=head3 Watcher-Specific Functions and Data Members
		1276
1076	=over 4	1277	=over 4
1077		1278
1078	=item ev_signal_init (ev_signal *, callback, int signum)	1279	=item ev_signal_init (ev_signal *, callback, int signum)
1079		1280
1080	=item ev_signal_set (ev_signal *, int signum)	1281	=item ev_signal_set (ev_signal *, int signum)
…		…
1091		1292
1092	=head2 C<ev_child> - watch out for process status changes	1293	=head2 C<ev_child> - watch out for process status changes
1093		1294
1094	Child watchers trigger when your process receives a SIGCHLD in response to	1295	Child watchers trigger when your process receives a SIGCHLD in response to
1095	some child status changes (most typically when a child of yours dies).	1296	some child status changes (most typically when a child of yours dies).
		1297
		1298	=head3 Watcher-Specific Functions and Data Members
1096		1299
1097	=over 4	1300	=over 4
1098		1301
1099	=item ev_child_init (ev_child *, callback, int pid)	1302	=item ev_child_init (ev_child *, callback, int pid)
1100		1303
…		…
1120	The process exit/trace status caused by C<rpid> (see your systems	1323	The process exit/trace status caused by C<rpid> (see your systems
1121	C<waitpid> and C<sys/wait.h> documentation for details).	1324	C<waitpid> and C<sys/wait.h> documentation for details).
1122		1325
1123	=back	1326	=back
1124		1327
1125	Example: try to exit cleanly on SIGINT and SIGTERM.	1328	Example: Try to exit cleanly on SIGINT and SIGTERM.
1126		1329
1127	static void	1330	static void
1128	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1331	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1129	{	1332	{
1130	ev_unloop (loop, EVUNLOOP_ALL);	1333	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1145	not exist" is a status change like any other. The condition "path does	1348	not exist" is a status change like any other. The condition "path does
1146	not exist" is signified by the C<st_nlink> field being zero (which is	1349	not exist" is signified by the C<st_nlink> field being zero (which is
1147	otherwise always forced to be at least one) and all the other fields of	1350	otherwise always forced to be at least one) and all the other fields of
1148	the stat buffer having unspecified contents.	1351	the stat buffer having unspecified contents.
1149		1352
		1353	The path I<should> be absolute and I<must not> end in a slash. If it is
		1354	relative and your working directory changes, the behaviour is undefined.
		1355
1150	Since there is no standard to do this, the portable implementation simply	1356	Since there is no standard to do this, the portable implementation simply
1151	calls C<stat (2)> regulalry on the path to see if it changed somehow. You	1357	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1152	can specify a recommended polling interval for this case. If you specify	1358	can specify a recommended polling interval for this case. If you specify
1153	a polling interval of C<0> (highly recommended!) then a I<suitable,	1359	a polling interval of C<0> (highly recommended!) then a I<suitable,
1154	unspecified default> value will be used (which you can expect to be around	1360	unspecified default> value will be used (which you can expect to be around
1155	five seconds, although this might change dynamically). Libev will also	1361	five seconds, although this might change dynamically). Libev will also
1156	impose a minimum interval which is currently around C<0.1>, but thats	1362	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1158		1364
1159	This watcher type is not meant for massive numbers of stat watchers,	1365	This watcher type is not meant for massive numbers of stat watchers,
1160	as even with OS-supported change notifications, this can be	1366	as even with OS-supported change notifications, this can be
1161	resource-intensive.	1367	resource-intensive.
1162		1368
1163	At the time of this writing, no specific OS backends are implemented, but	1369	At the time of this writing, only the Linux inotify interface is
1164	if demand increases, at least a kqueue and inotify backend will be added.	1370	implemented (implementing kqueue support is left as an exercise for the
		1371	reader). Inotify will be used to give hints only and should not change the
		1372	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1373	to fall back to regular polling again even with inotify, but changes are
		1374	usually detected immediately, and if the file exists there will be no
		1375	polling.
		1376
		1377	=head3 Watcher-Specific Functions and Data Members
1165		1378
1166	=over 4	1379	=over 4
1167		1380
1168	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1381	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1169		1382
…		…
1233	ev_stat_start (loop, &passwd);	1446	ev_stat_start (loop, &passwd);
1234		1447
1235		1448
1236	=head2 C<ev_idle> - when you've got nothing better to do...	1449	=head2 C<ev_idle> - when you've got nothing better to do...
1237		1450
1238	Idle watchers trigger events when there are no other events are pending	1451	Idle watchers trigger events when no other events of the same or higher
1239	(prepare, check and other idle watchers do not count). That is, as long	1452	priority are pending (prepare, check and other idle watchers do not
1240	as your process is busy handling sockets or timeouts (or even signals,	1453	count).
1241	imagine) it will not be triggered. But when your process is idle all idle	1454
1242	watchers are being called again and again, once per event loop iteration -	1455	That is, as long as your process is busy handling sockets or timeouts
		1456	(or even signals, imagine) of the same or higher priority it will not be
		1457	triggered. But when your process is idle (or only lower-priority watchers
		1458	are pending), the idle watchers are being called once per event loop
1243	until stopped, that is, or your process receives more events and becomes	1459	iteration - until stopped, that is, or your process receives more events
1244	busy.	1460	and becomes busy again with higher priority stuff.
1245		1461
1246	The most noteworthy effect is that as long as any idle watchers are	1462	The most noteworthy effect is that as long as any idle watchers are
1247	active, the process will not block when waiting for new events.	1463	active, the process will not block when waiting for new events.
1248		1464
1249	Apart from keeping your process non-blocking (which is a useful	1465	Apart from keeping your process non-blocking (which is a useful
1250	effect on its own sometimes), idle watchers are a good place to do	1466	effect on its own sometimes), idle watchers are a good place to do
1251	"pseudo-background processing", or delay processing stuff to after the	1467	"pseudo-background processing", or delay processing stuff to after the
1252	event loop has handled all outstanding events.	1468	event loop has handled all outstanding events.
1253		1469
		1470	=head3 Watcher-Specific Functions and Data Members
		1471
1254	=over 4	1472	=over 4
1255		1473
1256	=item ev_idle_init (ev_signal *, callback)	1474	=item ev_idle_init (ev_signal *, callback)
1257		1475
1258	Initialises and configures the idle watcher - it has no parameters of any	1476	Initialises and configures the idle watcher - it has no parameters of any
1259	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1477	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1260	believe me.	1478	believe me.
1261		1479
1262	=back	1480	=back
1263		1481
1264	Example: dynamically allocate an C<ev_idle>, start it, and in the	1482	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1265	callback, free it. Alos, use no error checking, as usual.	1483	callback, free it. Also, use no error checking, as usual.
1266		1484
1267	static void	1485	static void
1268	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1486	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1269	{	1487	{
1270	free (w);	1488	free (w);
…		…
1315	with priority higher than or equal to the event loop and one coroutine	1533	with priority higher than or equal to the event loop and one coroutine
1316	of lower priority, but only once, using idle watchers to keep the event	1534	of lower priority, but only once, using idle watchers to keep the event
1317	loop from blocking if lower-priority coroutines are active, thus mapping	1535	loop from blocking if lower-priority coroutines are active, thus mapping
1318	low-priority coroutines to idle/background tasks).	1536	low-priority coroutines to idle/background tasks).
1319		1537
		1538	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1539	priority, to ensure that they are being run before any other watchers
		1540	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1541	too) should not activate ("feed") events into libev. While libev fully
		1542	supports this, they will be called before other C<ev_check> watchers did
		1543	their job. As C<ev_check> watchers are often used to embed other event
		1544	loops those other event loops might be in an unusable state until their
		1545	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1546	others).
		1547
		1548	=head3 Watcher-Specific Functions and Data Members
		1549
1320	=over 4	1550	=over 4
1321		1551
1322	=item ev_prepare_init (ev_prepare *, callback)	1552	=item ev_prepare_init (ev_prepare *, callback)
1323		1553
1324	=item ev_check_init (ev_check *, callback)	1554	=item ev_check_init (ev_check *, callback)
…		…
1327	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1557	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1328	macros, but using them is utterly, utterly and completely pointless.	1558	macros, but using them is utterly, utterly and completely pointless.
1329		1559
1330	=back	1560	=back
1331		1561
1332	Example: To include a library such as adns, you would add IO watchers	1562	There are a number of principal ways to embed other event loops or modules
1333	and a timeout watcher in a prepare handler, as required by libadns, and	1563	into libev. Here are some ideas on how to include libadns into libev
		1564	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1565	use for an actually working example. Another Perl module named C<EV::Glib>
		1566	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1567	into the Glib event loop).
		1568
		1569	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1334	in a check watcher, destroy them and call into libadns. What follows is	1570	and in a check watcher, destroy them and call into libadns. What follows
1335	pseudo-code only of course:	1571	is pseudo-code only of course. This requires you to either use a low
		1572	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1573	the callbacks for the IO/timeout watchers might not have been called yet.
1336		1574
1337	static ev_io iow [nfd];	1575	static ev_io iow [nfd];
1338	static ev_timer tw;	1576	static ev_timer tw;
1339		1577
1340	static void	1578	static void
1341	io_cb (ev_loop loop, ev_io w, int revents)	1579	io_cb (ev_loop loop, ev_io w, int revents)
1342	{	1580	{
1343	// set the relevant poll flags
1344	// could also call adns_processreadable etc. here
1345	struct pollfd fd = (struct pollfd )w->data;
1346	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1347	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1348	}	1581	}
1349		1582
1350	// create io watchers for each fd and a timer before blocking	1583	// create io watchers for each fd and a timer before blocking
1351	static void	1584	static void
1352	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1585	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1353	{	1586	{
1354	int timeout = 3600000;truct pollfd fds [nfd];	1587	int timeout = 3600000;
		1588	struct pollfd fds [nfd];
1355	// actual code will need to loop here and realloc etc.	1589	// actual code will need to loop here and realloc etc.
1356	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1590	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1357		1591
1358	/* the callback is illegal, but won't be called as we stop during check */	1592	/* the callback is illegal, but won't be called as we stop during check */
1359	ev_timer_init (&tw, 0, timeout * 1e-3);	1593	ev_timer_init (&tw, 0, timeout * 1e-3);
1360	ev_timer_start (loop, &tw);	1594	ev_timer_start (loop, &tw);
1361		1595
1362	// create on ev_io per pollfd	1596	// create one ev_io per pollfd
1363	for (int i = 0; i < nfd; ++i)	1597	for (int i = 0; i < nfd; ++i)
1364	{	1598	{
1365	ev_io_init (iow + i, io_cb, fds [i].fd,	1599	ev_io_init (iow + i, io_cb, fds [i].fd,
1366	((fds [i].events & POLLIN ? EV_READ : 0)	1600	((fds [i].events & POLLIN ? EV_READ : 0)
1367	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1601	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1368		1602
1369	fds [i].revents = 0;	1603	fds [i].revents = 0;
1370	iow [i].data = fds + i;
1371	ev_io_start (loop, iow + i);	1604	ev_io_start (loop, iow + i);
1372	}	1605	}
1373	}	1606	}
1374		1607
1375	// stop all watchers after blocking	1608	// stop all watchers after blocking
…		…
1377	adns_check_cb (ev_loop loop, ev_check w, int revents)	1610	adns_check_cb (ev_loop loop, ev_check w, int revents)
1378	{	1611	{
1379	ev_timer_stop (loop, &tw);	1612	ev_timer_stop (loop, &tw);
1380		1613
1381	for (int i = 0; i < nfd; ++i)	1614	for (int i = 0; i < nfd; ++i)
		1615	{
		1616	// set the relevant poll flags
		1617	// could also call adns_processreadable etc. here
		1618	struct pollfd *fd = fds + i;
		1619	int revents = ev_clear_pending (iow + i);
		1620	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1621	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1622
		1623	// now stop the watcher
1382	ev_io_stop (loop, iow + i);	1624	ev_io_stop (loop, iow + i);
		1625	}
1383		1626
1384	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1627	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1628	}
		1629
		1630	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1631	in the prepare watcher and would dispose of the check watcher.
		1632
		1633	Method 3: If the module to be embedded supports explicit event
		1634	notification (adns does), you can also make use of the actual watcher
		1635	callbacks, and only destroy/create the watchers in the prepare watcher.
		1636
		1637	static void
		1638	timer_cb (EV_P_ ev_timer *w, int revents)
		1639	{
		1640	adns_state ads = (adns_state)w->data;
		1641	update_now (EV_A);
		1642
		1643	adns_processtimeouts (ads, &tv_now);
		1644	}
		1645
		1646	static void
		1647	io_cb (EV_P_ ev_io *w, int revents)
		1648	{
		1649	adns_state ads = (adns_state)w->data;
		1650	update_now (EV_A);
		1651
		1652	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1653	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1654	}
		1655
		1656	// do not ever call adns_afterpoll
		1657
		1658	Method 4: Do not use a prepare or check watcher because the module you
		1659	want to embed is too inflexible to support it. Instead, youc na override
		1660	their poll function. The drawback with this solution is that the main
		1661	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1662	this.
		1663
		1664	static gint
		1665	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1666	{
		1667	int got_events = 0;
		1668
		1669	for (n = 0; n < nfds; ++n)
		1670	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1671
		1672	if (timeout >= 0)
		1673	// create/start timer
		1674
		1675	// poll
		1676	ev_loop (EV_A_ 0);
		1677
		1678	// stop timer again
		1679	if (timeout >= 0)
		1680	ev_timer_stop (EV_A_ &to);
		1681
		1682	// stop io watchers again - their callbacks should have set
		1683	for (n = 0; n < nfds; ++n)
		1684	ev_io_stop (EV_A_ iow [n]);
		1685
		1686	return got_events;
1385	}	1687	}
1386		1688
1387		1689
1388	=head2 C<ev_embed> - when one backend isn't enough...	1690	=head2 C<ev_embed> - when one backend isn't enough...
1389		1691
…		…
1453	ev_embed_start (loop_hi, &embed);	1755	ev_embed_start (loop_hi, &embed);
1454	}	1756	}
1455	else	1757	else
1456	loop_lo = loop_hi;	1758	loop_lo = loop_hi;
1457		1759
		1760	=head3 Watcher-Specific Functions and Data Members
		1761
1458	=over 4	1762	=over 4
1459		1763
1460	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)	1764	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)
1461		1765
1462	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)	1766	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)
…		…
1488	event loop blocks next and before C<ev_check> watchers are being called,	1792	event loop blocks next and before C<ev_check> watchers are being called,
1489	and only in the child after the fork. If whoever good citizen calling	1793	and only in the child after the fork. If whoever good citizen calling
1490	C<ev_default_fork> cheats and calls it in the wrong process, the fork	1794	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1491	handlers will be invoked, too, of course.	1795	handlers will be invoked, too, of course.
1492		1796
		1797	=head3 Watcher-Specific Functions and Data Members
		1798
1493	=over 4	1799	=over 4
1494		1800
1495	=item ev_fork_init (ev_signal *, callback)	1801	=item ev_fork_init (ev_signal *, callback)
1496		1802
1497	Initialises and configures the fork watcher - it has no parameters of any	1803	Initialises and configures the fork watcher - it has no parameters of any
…		…
1593		1899
1594	To use it,	1900	To use it,
1595		1901
1596	#include <ev++.h>	1902	#include <ev++.h>
1597		1903
1598	(it is not installed by default). This automatically includes F<ev.h>	1904	This automatically includes F<ev.h> and puts all of its definitions (many
1599	and puts all of its definitions (many of them macros) into the global	1905	of them macros) into the global namespace. All C++ specific things are
1600	namespace. All C++ specific things are put into the C<ev> namespace.	1906	put into the C<ev> namespace. It should support all the same embedding
		1907	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1601		1908
1602	It should support all the same embedding options as F<ev.h>, most notably	1909	Care has been taken to keep the overhead low. The only data member the C++
1603	C<EV_MULTIPLICITY>.	1910	classes add (compared to plain C-style watchers) is the event loop pointer
		1911	that the watcher is associated with (or no additional members at all if
		1912	you disable C<EV_MULTIPLICITY> when embedding libev).
		1913
		1914	Currently, functions, and static and non-static member functions can be
		1915	used as callbacks. Other types should be easy to add as long as they only
		1916	need one additional pointer for context. If you need support for other
		1917	types of functors please contact the author (preferably after implementing
		1918	it).
1604		1919
1605	Here is a list of things available in the C<ev> namespace:	1920	Here is a list of things available in the C<ev> namespace:
1606		1921
1607	=over 4	1922	=over 4
1608		1923
…		…
1624		1939
1625	All of those classes have these methods:	1940	All of those classes have these methods:
1626		1941
1627	=over 4	1942	=over 4
1628		1943
1629	=item ev::TYPE::TYPE (object , object::method )	1944	=item ev::TYPE::TYPE ()
1630		1945
1631	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1946	=item ev::TYPE::TYPE (struct ev_loop *)
1632		1947
1633	=item ev::TYPE::~TYPE	1948	=item ev::TYPE::~TYPE
1634		1949
1635	The constructor takes a pointer to an object and a method pointer to	1950	The constructor (optionally) takes an event loop to associate the watcher
1636	the event handler callback to call in this class. The constructor calls	1951	with. If it is omitted, it will use C<EV_DEFAULT>.
1637	C<ev_init> for you, which means you have to call the C<set> method	1952
1638	before starting it. If you do not specify a loop then the constructor	1953	The constructor calls C<ev_init> for you, which means you have to call the
1639	automatically associates the default loop with this watcher.	1954	C<set> method before starting it.
		1955
		1956	It will not set a callback, however: You have to call the templated C<set>
		1957	method to set a callback before you can start the watcher.
		1958
		1959	(The reason why you have to use a method is a limitation in C++ which does
		1960	not allow explicit template arguments for constructors).
1640		1961
1641	The destructor automatically stops the watcher if it is active.	1962	The destructor automatically stops the watcher if it is active.
		1963
		1964	=item w->set<class, &class::method> (object *)
		1965
		1966	This method sets the callback method to call. The method has to have a
		1967	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1968	first argument and the C<revents> as second. The object must be given as
		1969	parameter and is stored in the C<data> member of the watcher.
		1970
		1971	This method synthesizes efficient thunking code to call your method from
		1972	the C callback that libev requires. If your compiler can inline your
		1973	callback (i.e. it is visible to it at the place of the C<set> call and
		1974	your compiler is good :), then the method will be fully inlined into the
		1975	thunking function, making it as fast as a direct C callback.
		1976
		1977	Example: simple class declaration and watcher initialisation
		1978
		1979	struct myclass
		1980	{
		1981	void io_cb (ev::io &w, int revents) { }
		1982	}
		1983
		1984	myclass obj;
		1985	ev::io iow;
		1986	iow.set <myclass, &myclass::io_cb> (&obj);
		1987
		1988	=item w->set<function> (void *data = 0)
		1989
		1990	Also sets a callback, but uses a static method or plain function as
		1991	callback. The optional C<data> argument will be stored in the watcher's
		1992	C<data> member and is free for you to use.
		1993
		1994	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		1995
		1996	See the method-C<set> above for more details.
		1997
		1998	Example:
		1999
		2000	static void io_cb (ev::io &w, int revents) { }
		2001	iow.set <io_cb> ();
1642		2002
1643	=item w->set (struct ev_loop *)	2003	=item w->set (struct ev_loop *)
1644		2004
1645	Associates a different C<struct ev_loop> with this watcher. You can only	2005	Associates a different C<struct ev_loop> with this watcher. You can only
1646	do this when the watcher is inactive (and not pending either).	2006	do this when the watcher is inactive (and not pending either).
1647		2007
1648	=item w->set ([args])	2008	=item w->set ([args])
1649		2009
1650	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2010	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1651	called at least once. Unlike the C counterpart, an active watcher gets	2011	called at least once. Unlike the C counterpart, an active watcher gets
1652	automatically stopped and restarted.	2012	automatically stopped and restarted when reconfiguring it with this
		2013	method.
1653		2014
1654	=item w->start ()	2015	=item w->start ()
1655		2016
1656	Starts the watcher. Note that there is no C<loop> argument as the	2017	Starts the watcher. Note that there is no C<loop> argument, as the
1657	constructor already takes the loop.	2018	constructor already stores the event loop.
1658		2019
1659	=item w->stop ()	2020	=item w->stop ()
1660		2021
1661	Stops the watcher if it is active. Again, no C<loop> argument.	2022	Stops the watcher if it is active. Again, no C<loop> argument.
1662		2023
…		…
1687		2048
1688	myclass ();	2049	myclass ();
1689	}	2050	}
1690		2051
1691	myclass::myclass (int fd)	2052	myclass::myclass (int fd)
1692	: io (this, &myclass::io_cb),
1693	idle (this, &myclass::idle_cb)
1694	{	2053	{
		2054	io .set <myclass, &myclass::io_cb > (this);
		2055	idle.set <myclass, &myclass::idle_cb> (this);
		2056
1695	io.start (fd, ev::READ);	2057	io.start (fd, ev::READ);
1696	}	2058	}
1697		2059
1698		2060
1699	=head1 MACRO MAGIC	2061	=head1 MACRO MAGIC
1700		2062
1701	Libev can be compiled with a variety of options, the most fundemantal is	2063	Libev can be compiled with a variety of options, the most fundemantal is
1702	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2064	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
1703	callbacks have an initial C<struct ev_loop *> argument.	2065	callbacks have an initial C<struct ev_loop *> argument.
1704		2066
1705	To make it easier to write programs that cope with either variant, the	2067	To make it easier to write programs that cope with either variant, the
1706	following macros are defined:	2068	following macros are defined:
1707		2069
…		…
1740	Similar to the other two macros, this gives you the value of the default	2102	Similar to the other two macros, this gives you the value of the default
1741	loop, if multiple loops are supported ("ev loop default").	2103	loop, if multiple loops are supported ("ev loop default").
1742		2104
1743	=back	2105	=back
1744		2106
1745	Example: Declare and initialise a check watcher, working regardless of	2107	Example: Declare and initialise a check watcher, utilising the above
1746	wether multiple loops are supported or not.	2108	macros so it will work regardless of whether multiple loops are supported
		2109	or not.
1747		2110
1748	static void	2111	static void
1749	check_cb (EV_P_ ev_timer *w, int revents)	2112	check_cb (EV_P_ ev_timer *w, int revents)
1750	{	2113	{
1751	ev_check_stop (EV_A_ w);	2114	ev_check_stop (EV_A_ w);
…		…
1753		2116
1754	ev_check check;	2117	ev_check check;
1755	ev_check_init (&check, check_cb);	2118	ev_check_init (&check, check_cb);
1756	ev_check_start (EV_DEFAULT_ &check);	2119	ev_check_start (EV_DEFAULT_ &check);
1757	ev_loop (EV_DEFAULT_ 0);	2120	ev_loop (EV_DEFAULT_ 0);
1758
1759		2121
1760	=head1 EMBEDDING	2122	=head1 EMBEDDING
1761		2123
1762	Libev can (and often is) directly embedded into host	2124	Libev can (and often is) directly embedded into host
1763	applications. Examples of applications that embed it include the Deliantra	2125	applications. Examples of applications that embed it include the Deliantra
…		…
1803	ev_vars.h	2165	ev_vars.h
1804	ev_wrap.h	2166	ev_wrap.h
1805		2167
1806	ev_win32.c required on win32 platforms only	2168	ev_win32.c required on win32 platforms only
1807		2169
1808	ev_select.c only when select backend is enabled (which is by default)	2170	ev_select.c only when select backend is enabled (which is enabled by default)
1809	ev_poll.c only when poll backend is enabled (disabled by default)	2171	ev_poll.c only when poll backend is enabled (disabled by default)
1810	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2172	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1811	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2173	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1812	ev_port.c only when the solaris port backend is enabled (disabled by default)	2174	ev_port.c only when the solaris port backend is enabled (disabled by default)
1813		2175
…		…
1938		2300
1939	=item EV_USE_DEVPOLL	2301	=item EV_USE_DEVPOLL
1940		2302
1941	reserved for future expansion, works like the USE symbols above.	2303	reserved for future expansion, works like the USE symbols above.
1942		2304
		2305	=item EV_USE_INOTIFY
		2306
		2307	If defined to be C<1>, libev will compile in support for the Linux inotify
		2308	interface to speed up C<ev_stat> watchers. Its actual availability will
		2309	be detected at runtime.
		2310
1943	=item EV_H	2311	=item EV_H
1944		2312
1945	The name of the F<ev.h> header file used to include it. The default if	2313	The name of the F<ev.h> header file used to include it. The default if
1946	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2314	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
1947	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2315	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
1970	will have the C<struct ev_loop *> as first argument, and you can create	2338	will have the C<struct ev_loop *> as first argument, and you can create
1971	additional independent event loops. Otherwise there will be no support	2339	additional independent event loops. Otherwise there will be no support
1972	for multiple event loops and there is no first event loop pointer	2340	for multiple event loops and there is no first event loop pointer
1973	argument. Instead, all functions act on the single default loop.	2341	argument. Instead, all functions act on the single default loop.
1974		2342
		2343	=item EV_MINPRI
		2344
		2345	=item EV_MAXPRI
		2346
		2347	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2348	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2349	provide for more priorities by overriding those symbols (usually defined
		2350	to be C<-2> and C<2>, respectively).
		2351
		2352	When doing priority-based operations, libev usually has to linearly search
		2353	all the priorities, so having many of them (hundreds) uses a lot of space
		2354	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2355	fine.
		2356
		2357	If your embedding app does not need any priorities, defining these both to
		2358	C<0> will save some memory and cpu.
		2359
1975	=item EV_PERIODIC_ENABLE	2360	=item EV_PERIODIC_ENABLE
1976		2361
1977	If undefined or defined to be C<1>, then periodic timers are supported. If	2362	If undefined or defined to be C<1>, then periodic timers are supported. If
1978	defined to be C<0>, then they are not. Disabling them saves a few kB of	2363	defined to be C<0>, then they are not. Disabling them saves a few kB of
1979	code.	2364	code.
1980		2365
		2366	=item EV_IDLE_ENABLE
		2367
		2368	If undefined or defined to be C<1>, then idle watchers are supported. If
		2369	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2370	code.
		2371
1981	=item EV_EMBED_ENABLE	2372	=item EV_EMBED_ENABLE
1982		2373
1983	If undefined or defined to be C<1>, then embed watchers are supported. If	2374	If undefined or defined to be C<1>, then embed watchers are supported. If
1984	defined to be C<0>, then they are not.	2375	defined to be C<0>, then they are not.
1985		2376
…		…
2002	=item EV_PID_HASHSIZE	2393	=item EV_PID_HASHSIZE
2003		2394
2004	C<ev_child> watchers use a small hash table to distribute workload by	2395	C<ev_child> watchers use a small hash table to distribute workload by
2005	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	2396	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
2006	than enough. If you need to manage thousands of children you might want to	2397	than enough. If you need to manage thousands of children you might want to
2007	increase this value.	2398	increase this value (I<must> be a power of two).
		2399
		2400	=item EV_INOTIFY_HASHSIZE
		2401
		2402	C<ev_staz> watchers use a small hash table to distribute workload by
		2403	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2404	usually more than enough. If you need to manage thousands of C<ev_stat>
		2405	watchers you might want to increase this value (I<must> be a power of
		2406	two).
2008		2407
2009	=item EV_COMMON	2408	=item EV_COMMON
2010		2409
2011	By default, all watchers have a C<void *data> member. By redefining	2410	By default, all watchers have a C<void *data> member. By redefining
2012	this macro to a something else you can include more and other types of	2411	this macro to a something else you can include more and other types of
…		…
2041	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2440	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2042	will be compiled. It is pretty complex because it provides its own header	2441	will be compiled. It is pretty complex because it provides its own header
2043	file.	2442	file.
2044		2443
2045	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2444	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2046	that everybody includes and which overrides some autoconf choices:	2445	that everybody includes and which overrides some configure choices:
2047		2446
		2447	#define EV_MINIMAL 1
2048	#define EV_USE_POLL 0	2448	#define EV_USE_POLL 0
2049	#define EV_MULTIPLICITY 0	2449	#define EV_MULTIPLICITY 0
2050	#define EV_PERIODICS 0	2450	#define EV_PERIODIC_ENABLE 0
		2451	#define EV_STAT_ENABLE 0
		2452	#define EV_FORK_ENABLE 0
2051	#define EV_CONFIG_H <config.h>	2453	#define EV_CONFIG_H <config.h>
		2454	#define EV_MINPRI 0
		2455	#define EV_MAXPRI 0
2052		2456
2053	#include "ev++.h"	2457	#include "ev++.h"
2054		2458
2055	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2459	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2056		2460
…		…
2062		2466
2063	In this section the complexities of (many of) the algorithms used inside	2467	In this section the complexities of (many of) the algorithms used inside
2064	libev will be explained. For complexity discussions about backends see the	2468	libev will be explained. For complexity discussions about backends see the
2065	documentation for C<ev_default_init>.	2469	documentation for C<ev_default_init>.
2066		2470
		2471	All of the following are about amortised time: If an array needs to be
		2472	extended, libev needs to realloc and move the whole array, but this
		2473	happens asymptotically never with higher number of elements, so O(1) might
		2474	mean it might do a lengthy realloc operation in rare cases, but on average
		2475	it is much faster and asymptotically approaches constant time.
		2476
2067	=over 4	2477	=over 4
2068		2478
2069	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2479	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2070		2480
		2481	This means that, when you have a watcher that triggers in one hour and
		2482	there are 100 watchers that would trigger before that then inserting will
		2483	have to skip those 100 watchers.
		2484
2071	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2485	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2072		2486
		2487	That means that for changing a timer costs less than removing/adding them
		2488	as only the relative motion in the event queue has to be paid for.
		2489
2073	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2490	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2074		2491
		2492	These just add the watcher into an array or at the head of a list.
2075	=item Stopping check/prepare/idle watchers: O(1)	2493	=item Stopping check/prepare/idle watchers: O(1)
2076		2494
2077	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2495	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2496
		2497	These watchers are stored in lists then need to be walked to find the
		2498	correct watcher to remove. The lists are usually short (you don't usually
		2499	have many watchers waiting for the same fd or signal).
2078		2500
2079	=item Finding the next timer per loop iteration: O(1)	2501	=item Finding the next timer per loop iteration: O(1)
2080		2502
2081	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2503	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2082		2504
		2505	A change means an I/O watcher gets started or stopped, which requires
		2506	libev to recalculate its status (and possibly tell the kernel).
		2507
2083	=item Activating one watcher: O(1)	2508	=item Activating one watcher: O(1)
2084		2509
		2510	=item Priority handling: O(number_of_priorities)
		2511
		2512	Priorities are implemented by allocating some space for each
		2513	priority. When doing priority-based operations, libev usually has to
		2514	linearly search all the priorities.
		2515
2085	=back	2516	=back
2086		2517
2087		2518
2088	=head1 AUTHOR	2519	=head1 AUTHOR
2089		2520

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Comparing libev/ev.pod (file contents): Revision 1.52 by root, Tue Nov 27 19:41:52 2007 UTC vs. Revision 1.83 by root, Wed Dec 12 17:55:31 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.52 by root, Tue Nov 27 19:41:52 2007 UTC vs.
Revision 1.83 by root, Wed Dec 12 17:55:31 2007 UTC