[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 1.86 by root, Tue Dec 18 01:20:33 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 some floatingpoint value. Unlike the name
		104	component C<stamp> might indicate, it is also used for time differences
		105	throughout libev.
52		106
53	=head1 GLOBAL FUNCTIONS	107	=head1 GLOBAL FUNCTIONS
54		108
55	These functions can be called anytime, even before initialising the	109	These functions can be called anytime, even before initialising the
56	library in any way.	110	library in any way.
…		…
65		119
66	=item int ev_version_major ()	120	=item int ev_version_major ()
67		121
68	=item int ev_version_minor ()	122	=item int ev_version_minor ()
69		123
70	You can find out the major and minor version numbers of the library	124	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	125	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	126	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	127	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
74	version of the library your program was compiled against.	128	version of the library your program was compiled against.
75		129
		130	These version numbers refer to the ABI version of the library, not the
		131	release version.
		132
76	Usually, it's a good idea to terminate if the major versions mismatch,	133	Usually, it's a good idea to terminate if the major versions mismatch,
77	as this indicates an incompatible change. Minor versions are usually	134	as this indicates an incompatible change. Minor versions are usually
78	compatible to older versions, so a larger minor version alone is usually	135	compatible to older versions, so a larger minor version alone is usually
79	not a problem.	136	not a problem.
80		137
81	Example: make sure we haven't accidentally been linked against the wrong	138	Example: Make sure we haven't accidentally been linked against the wrong
82	version:	139	version.
83		140
84	assert (("libev version mismatch",	141	assert (("libev version mismatch",
85	ev_version_major () == EV_VERSION_MAJOR	142	ev_version_major () == EV_VERSION_MAJOR
86	&& ev_version_minor () >= EV_VERSION_MINOR));	143	&& ev_version_minor () >= EV_VERSION_MINOR));
87		144
…		…
115	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	172	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
116	recommended ones.	173	recommended ones.
117		174
118	See the description of C<ev_embed> watchers for more info.	175	See the description of C<ev_embed> watchers for more info.
119		176
120	=item ev_set_allocator (void (cb)(void *ptr, size_t size))	177	=item ev_set_allocator (void (cb)(void *ptr, long size))
121		178
122	Sets the allocation function to use (the prototype and semantics are	179	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	180	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	181	allocate and free memory (no surprises here). If it returns zero when
125	allocated, the library might abort or take some potentially destructive	182	memory needs to be allocated, the library might abort or take some
126	action. The default is your system realloc function.	183	potentially destructive action. The default is your system realloc
		184	function.
127		185
128	You could override this function in high-availability programs to, say,	186	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,	187	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.	188	or even to sleep a while and retry until some memory is available.
131		189
132	Example: replace the libev allocator with one that waits a bit and then	190	Example: Replace the libev allocator with one that waits a bit and then
133	retries: better than mine).	191	retries).
134		192
135	static void *	193	static void *
136	persistent_realloc (void *ptr, size_t size)	194	persistent_realloc (void *ptr, size_t size)
137	{	195	{
138	for (;;)	196	for (;;)
…		…
157	callback is set, then libev will expect it to remedy the sitution, no	215	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	216	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	217	requested operation, or, if the condition doesn't go away, do bad stuff
160	(such as abort).	218	(such as abort).
161		219
162	Example: do the same thing as libev does internally:	220	Example: This is basically the same thing that libev does internally, too.
163		221
164	static void	222	static void
165	fatal_error (const char *msg)	223	fatal_error (const char *msg)
166	{	224	{
167	perror (msg);	225	perror (msg);
…		…
217	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	275	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
218	override the flags completely if it is found in the environment. This is	276	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	277	useful to try out specific backends to test their performance, or to work
220	around bugs.	278	around bugs.
221		279
		280	=item C<EVFLAG_FORKCHECK>
		281
		282	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		283	a fork, you can also make libev check for a fork in each iteration by
		284	enabling this flag.
		285
		286	This works by calling C<getpid ()> on every iteration of the loop,
		287	and thus this might slow down your event loop if you do a lot of loop
		288	iterations and little real work, but is usually not noticeable (on my
		289	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		290	without a syscall and thus I<very> fast, but my Linux system also has
		291	C<pthread_atfork> which is even faster).
		292
		293	The big advantage of this flag is that you can forget about fork (and
		294	forget about forgetting to tell libev about forking) when you use this
		295	flag.
		296
		297	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		298	environment variable.
		299
222	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	300	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
223		301
224	This is your standard select(2) backend. Not I<completely> standard, as	302	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,	303	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	304	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	391	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	392	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	393	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).	394	undefined behaviour (or a failed assertion if assertions are enabled).
317		395
318	Example: try to create a event loop that uses epoll and nothing else.	396	Example: Try to create a event loop that uses epoll and nothing else.
319		397
320	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	398	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
321	if (!epoller)	399	if (!epoller)
322	fatal ("no epoll found here, maybe it hides under your chair");	400	fatal ("no epoll found here, maybe it hides under your chair");
323		401
…		…
361		439
362	Like C<ev_default_fork>, but acts on an event loop created by	440	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	441	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.	442	after fork, and how you do this is entirely your own problem.
365		443
		444	=item unsigned int ev_loop_count (loop)
		445
		446	Returns the count of loop iterations for the loop, which is identical to
		447	the number of times libev did poll for new events. It starts at C<0> and
		448	happily wraps around with enough iterations.
		449
		450	This value can sometimes be useful as a generation counter of sorts (it
		451	"ticks" the number of loop iterations), as it roughly corresponds with
		452	C<ev_prepare> and C<ev_check> calls.
		453
366	=item unsigned int ev_backend (loop)	454	=item unsigned int ev_backend (loop)
367		455
368	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	456	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
369	use.	457	use.
370		458
…		…
403	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	491	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
404	usually a better approach for this kind of thing.	492	usually a better approach for this kind of thing.
405		493
406	Here are the gory details of what C<ev_loop> does:	494	Here are the gory details of what C<ev_loop> does:
407		495
		496	- Before the first iteration, call any pending watchers.
408	* If there are no active watchers (reference count is zero), return.	497	* If there are no active watchers (reference count is zero), return.
409	- Queue prepare watchers and then call all outstanding watchers.	498	- Queue all prepare watchers and then call all outstanding watchers.
410	- If we have been forked, recreate the kernel state.	499	- If we have been forked, recreate the kernel state.
411	- Update the kernel state with all outstanding changes.	500	- Update the kernel state with all outstanding changes.
412	- Update the "event loop time".	501	- Update the "event loop time".
413	- Calculate for how long to block.	502	- Calculate for how long to block.
414	- Block the process, waiting for any events.	503	- Block the process, waiting for any events.
…		…
422	Signals and child watchers are implemented as I/O watchers, and will	511	Signals and child watchers are implemented as I/O watchers, and will
423	be handled here by queueing them when their watcher gets executed.	512	be handled here by queueing them when their watcher gets executed.
424	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	513	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
425	were used, return, otherwise continue with step *.	514	were used, return, otherwise continue with step *.
426		515
427	Example: queue some jobs and then loop until no events are outsanding	516	Example: Queue some jobs and then loop until no events are outsanding
428	anymore.	517	anymore.
429		518
430	... queue jobs here, make sure they register event watchers as long	519	... 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..)	520	... as they still have work to do (even an idle watcher will do..)
432	ev_loop (my_loop, 0);	521	ev_loop (my_loop, 0);
…		…
452	visible to the libev user and should not keep C<ev_loop> from exiting if	541	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	542	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	543	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>.	544	libraries. Just remember to I<unref after start> and I<ref before stop>.
456		545
457	Example: create a signal watcher, but keep it from keeping C<ev_loop>	546	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
458	running when nothing else is active.	547	running when nothing else is active.
459		548
460	struct dv_signal exitsig;	549	struct ev_signal exitsig;
461	ev_signal_init (&exitsig, sig_cb, SIGINT);	550	ev_signal_init (&exitsig, sig_cb, SIGINT);
462	ev_signal_start (myloop, &exitsig);	551	ev_signal_start (loop, &exitsig);
463	evf_unref (myloop);	552	evf_unref (loop);
464		553
465	Example: for some weird reason, unregister the above signal handler again.	554	Example: For some weird reason, unregister the above signal handler again.
466		555
467	ev_ref (myloop);	556	ev_ref (loop);
468	ev_signal_stop (myloop, &exitsig);	557	ev_signal_stop (loop, &exitsig);
469		558
470	=back	559	=back
471		560
472		561
473	=head1 ANATOMY OF A WATCHER	562	=head1 ANATOMY OF A WATCHER
…		…
653	=item bool ev_is_pending (ev_TYPE *watcher)	742	=item bool ev_is_pending (ev_TYPE *watcher)
654		743
655	Returns a true value iff the watcher is pending, (i.e. it has outstanding	744	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	745	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	746	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	747	C<ev_TYPE_set> is safe), you must not change its priority, and you must
659	libev (e.g. you cnanot C<free ()> it).	748	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		749	it).
660		750
661	=item callback = ev_cb (ev_TYPE *watcher)	751	=item callback ev_cb (ev_TYPE *watcher)
662		752
663	Returns the callback currently set on the watcher.	753	Returns the callback currently set on the watcher.
664		754
665	=item ev_cb_set (ev_TYPE *watcher, callback)	755	=item ev_cb_set (ev_TYPE *watcher, callback)
666		756
667	Change the callback. You can change the callback at virtually any time	757	Change the callback. You can change the callback at virtually any time
668	(modulo threads).	758	(modulo threads).
		759
		760	=item ev_set_priority (ev_TYPE *watcher, priority)
		761
		762	=item int ev_priority (ev_TYPE *watcher)
		763
		764	Set and query the priority of the watcher. The priority is a small
		765	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		766	(default: C<-2>). Pending watchers with higher priority will be invoked
		767	before watchers with lower priority, but priority will not keep watchers
		768	from being executed (except for C<ev_idle> watchers).
		769
		770	This means that priorities are I<only> used for ordering callback
		771	invocation after new events have been received. This is useful, for
		772	example, to reduce latency after idling, or more often, to bind two
		773	watchers on the same event and make sure one is called first.
		774
		775	If you need to suppress invocation when higher priority events are pending
		776	you need to look at C<ev_idle> watchers, which provide this functionality.
		777
		778	You I<must not> change the priority of a watcher as long as it is active or
		779	pending.
		780
		781	The default priority used by watchers when no priority has been set is
		782	always C<0>, which is supposed to not be too high and not be too low :).
		783
		784	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		785	fine, as long as you do not mind that the priority value you query might
		786	or might not have been adjusted to be within valid range.
		787
		788	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		789
		790	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		791	C<loop> nor C<revents> need to be valid as long as the watcher callback
		792	can deal with that fact.
		793
		794	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		795
		796	If the watcher is pending, this function returns clears its pending status
		797	and returns its C<revents> bitset (as if its callback was invoked). If the
		798	watcher isn't pending it does nothing and returns C<0>.
669		799
670	=back	800	=back
671		801
672		802
673	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	803	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
694	{	824	{
695	struct my_io w = (struct my_io )w_;	825	struct my_io w = (struct my_io )w_;
696	...	826	...
697	}	827	}
698		828
699	More interesting and less C-conformant ways of catsing your callback type	829	More interesting and less C-conformant ways of casting your callback type
700	have been omitted....	830	instead have been omitted.
		831
		832	Another common scenario is having some data structure with multiple
		833	watchers:
		834
		835	struct my_biggy
		836	{
		837	int some_data;
		838	ev_timer t1;
		839	ev_timer t2;
		840	}
		841
		842	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		843	you need to use C<offsetof>:
		844
		845	#include <stddef.h>
		846
		847	static void
		848	t1_cb (EV_P_ struct ev_timer *w, int revents)
		849	{
		850	struct my_biggy big = (struct my_biggy *
		851	(((char *)w) - offsetof (struct my_biggy, t1));
		852	}
		853
		854	static void
		855	t2_cb (EV_P_ struct ev_timer *w, int revents)
		856	{
		857	struct my_biggy big = (struct my_biggy *
		858	(((char *)w) - offsetof (struct my_biggy, t2));
		859	}
701		860
702		861
703	=head1 WATCHER TYPES	862	=head1 WATCHER TYPES
704		863
705	This section describes each watcher in detail, but will not repeat	864	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	909	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.	910	C<EAGAIN> is far preferable to a program hanging until some data arrives.
752		911
753	If you cannot run the fd in non-blocking mode (for example you should not	912	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	913	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	914	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	915	such as poll (fortunately in our Xlib example, Xlib already does this on
757	its own, so its quite safe to use).	916	its own, so its quite safe to use).
		917
		918	=head3 The special problem of disappearing file descriptors
		919
		920	Some backends (e.g kqueue, epoll) need to be told about closing a file
		921	descriptor (either by calling C<close> explicitly or by any other means,
		922	such as C<dup>). The reason is that you register interest in some file
		923	descriptor, but when it goes away, the operating system will silently drop
		924	this interest. If another file descriptor with the same number then is
		925	registered with libev, there is no efficient way to see that this is, in
		926	fact, a different file descriptor.
		927
		928	To avoid having to explicitly tell libev about such cases, libev follows
		929	the following policy: Each time C<ev_io_set> is being called, libev
		930	will assume that this is potentially a new file descriptor, otherwise
		931	it is assumed that the file descriptor stays the same. That means that
		932	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		933	descriptor even if the file descriptor number itself did not change.
		934
		935	This is how one would do it normally anyway, the important point is that
		936	the libev application should not optimise around libev but should leave
		937	optimisations to libev.
		938
		939
		940	=head3 Watcher-Specific Functions
758		941
759	=over 4	942	=over 4
760		943
761	=item ev_io_init (ev_io *, callback, int fd, int events)	944	=item ev_io_init (ev_io *, callback, int fd, int events)
762		945
…		…
774		957
775	The events being watched.	958	The events being watched.
776		959
777	=back	960	=back
778		961
779	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	962	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	963	readable, but only once. Since it is likely line-buffered, you could
781	attempt to read a whole line in the callback:	964	attempt to read a whole line in the callback.
782		965
783	static void	966	static void
784	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	967	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
785	{	968	{
786	ev_io_stop (loop, w);	969	ev_io_stop (loop, w);
…		…
816		999
817	The callback is guarenteed to be invoked only when its timeout has passed,	1000	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	1001	but if multiple timers become ready during the same loop iteration then
819	order of execution is undefined.	1002	order of execution is undefined.
820		1003
		1004	=head3 Watcher-Specific Functions and Data Members
		1005
821	=over 4	1006	=over 4
822		1007
823	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1008	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
824		1009
825	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1010	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
838	=item ev_timer_again (loop)	1023	=item ev_timer_again (loop)
839		1024
840	This will act as if the timer timed out and restart it again if it is	1025	This will act as if the timer timed out and restart it again if it is
841	repeating. The exact semantics are:	1026	repeating. The exact semantics are:
842		1027
		1028	If the timer is pending, its pending status is cleared.
		1029
843	If the timer is started but nonrepeating, stop it.	1030	If the timer is started but nonrepeating, stop it (as if it timed out).
844		1031
845	If the timer is repeating, either start it if necessary (with the repeat	1032	If the timer is repeating, either start it if necessary (with the
846	value), or reset the running timer to the repeat value.	1033	C<repeat> value), or reset the running timer to the C<repeat> value.
847		1034
848	This sounds a bit complicated, but here is a useful and typical	1035	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	1036	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,	1037	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	1038	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	1039	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	1040	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	1041	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	1042	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
856	need be.	1043	automatically restart it if need be.
857		1044
858	You can also ignore the C<after> value and C<ev_timer_start> altogether	1045	That means you can ignore the C<after> value and C<ev_timer_start>
859	and only ever use the C<repeat> value:	1046	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
860		1047
861	ev_timer_init (timer, callback, 0., 5.);	1048	ev_timer_init (timer, callback, 0., 5.);
862	ev_timer_again (loop, timer);	1049	ev_timer_again (loop, timer);
863	...	1050	...
864	timer->again = 17.;	1051	timer->again = 17.;
865	ev_timer_again (loop, timer);	1052	ev_timer_again (loop, timer);
866	...	1053	...
867	timer->again = 10.;	1054	timer->again = 10.;
868	ev_timer_again (loop, timer);	1055	ev_timer_again (loop, timer);
869		1056
870	This is more efficient then stopping/starting the timer eahc time you want	1057	This is more slightly efficient then stopping/starting the timer each time
871	to modify its timeout value.	1058	you want to modify its timeout value.
872		1059
873	=item ev_tstamp repeat [read-write]	1060	=item ev_tstamp repeat [read-write]
874		1061
875	The current C<repeat> value. Will be used each time the watcher times out	1062	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),	1063	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.	1064	which is also when any modifications are taken into account.
878		1065
879	=back	1066	=back
880		1067
881	Example: create a timer that fires after 60 seconds.	1068	Example: Create a timer that fires after 60 seconds.
882		1069
883	static void	1070	static void
884	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	1071	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
885	{	1072	{
886	.. one minute over, w is actually stopped right here	1073	.. one minute over, w is actually stopped right here
…		…
888		1075
889	struct ev_timer mytimer;	1076	struct ev_timer mytimer;
890	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1077	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
891	ev_timer_start (loop, &mytimer);	1078	ev_timer_start (loop, &mytimer);
892		1079
893	Example: create a timeout timer that times out after 10 seconds of	1080	Example: Create a timeout timer that times out after 10 seconds of
894	inactivity.	1081	inactivity.
895		1082
896	static void	1083	static void
897	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1084	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
898	{	1085	{
…		…
918	but on wallclock time (absolute time). You can tell a periodic watcher	1105	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	1106	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 ()	1107	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	1108	+ 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	1109	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	1110	roughly 10 seconds later).
924	again).
925		1111
926	They can also be used to implement vastly more complex timers, such as	1112	They can also be used to implement vastly more complex timers, such as
927	triggering an event on eahc midnight, local time.	1113	triggering an event on each midnight, local time or other, complicated,
		1114	rules.
928		1115
929	As with timers, the callback is guarenteed to be invoked only when the	1116	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	1117	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.	1118	during the same loop iteration then order of execution is undefined.
932		1119
		1120	=head3 Watcher-Specific Functions and Data Members
		1121
933	=over 4	1122	=over 4
934		1123
935	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1124	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
936		1125
937	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1126	=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	1128	Lots of arguments, lets sort it out... There are basically three modes of
940	operation, and we will explain them from simplest to complex:	1129	operation, and we will explain them from simplest to complex:
941		1130
942	=over 4	1131	=over 4
943		1132
944	=item * absolute timer (interval = reschedule_cb = 0)	1133	=item * absolute timer (at = time, interval = reschedule_cb = 0)
945		1134
946	In this configuration the watcher triggers an event at the wallclock time	1135	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,	1136	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	1137	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.	1138	system time reaches or surpasses this time.
950		1139
951	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1140	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
952		1141
953	In this mode the watcher will always be scheduled to time out at the next	1142	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	1143	C<at + N * interval> time (for some integer N, which can also be negative)
955	of any time jumps.	1144	and then repeat, regardless of any time jumps.
956		1145
957	This can be used to create timers that do not drift with respect to system	1146	This can be used to create timers that do not drift with respect to system
958	time:	1147	time:
959		1148
960	ev_periodic_set (&periodic, 0., 3600., 0);	1149	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
966		1155
967	Another way to think about it (for the mathematically inclined) is that	1156	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	1157	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.	1158	time where C<time = at (mod interval)>, regardless of any time jumps.
970		1159
		1160	For numerical stability it is preferable that the C<at> value is near
		1161	C<ev_now ()> (the current time), but there is no range requirement for
		1162	this value.
		1163
971	=item * manual reschedule mode (reschedule_cb = callback)	1164	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
972		1165
973	In this mode the values for C<interval> and C<at> are both being	1166	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	1167	ignored. Instead, each time the periodic watcher gets scheduled, the
975	reschedule callback will be called with the watcher as first, and the	1168	reschedule callback will be called with the watcher as first, and the
976	current time as second argument.	1169	current time as second argument.
977		1170
978	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1171	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,	1172	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	1173	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
981	starting a prepare watcher).	1174	starting an C<ev_prepare> watcher, which is legal).
982		1175
983	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	1176	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
984	ev_tstamp now)>, e.g.:	1177	ev_tstamp now)>, e.g.:
985		1178
986	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1179	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	1202	Simply stops and restarts the periodic watcher again. This is only useful
1010	when you changed some parameters or the reschedule callback would return	1203	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	1204	a different time than the last time it was called (e.g. in a crond like
1012	program when the crontabs have changed).	1205	program when the crontabs have changed).
1013		1206
		1207	=item ev_tstamp offset [read-write]
		1208
		1209	When repeating, this contains the offset value, otherwise this is the
		1210	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1211
		1212	Can be modified any time, but changes only take effect when the periodic
		1213	timer fires or C<ev_periodic_again> is being called.
		1214
1014	=item ev_tstamp interval [read-write]	1215	=item ev_tstamp interval [read-write]
1015		1216
1016	The current interval value. Can be modified any time, but changes only	1217	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	1218	take effect when the periodic timer fires or C<ev_periodic_again> is being
1018	called.	1219	called.
…		…
1021		1222
1022	The current reschedule callback, or C<0>, if this functionality is	1223	The current reschedule callback, or C<0>, if this functionality is
1023	switched off. Can be changed any time, but changes only take effect when	1224	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.	1225	the periodic timer fires or C<ev_periodic_again> is being called.
1025		1226
		1227	=item ev_tstamp at [read-only]
		1228
		1229	When active, contains the absolute time that the watcher is supposed to
		1230	trigger next.
		1231
1026	=back	1232	=back
1027		1233
1028	Example: call a callback every hour, or, more precisely, whenever the	1234	Example: Call a callback every hour, or, more precisely, whenever the
1029	system clock is divisible by 3600. The callback invocation times have	1235	system clock is divisible by 3600. The callback invocation times have
1030	potentially a lot of jittering, but good long-term stability.	1236	potentially a lot of jittering, but good long-term stability.
1031		1237
1032	static void	1238	static void
1033	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1239	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
1037		1243
1038	struct ev_periodic hourly_tick;	1244	struct ev_periodic hourly_tick;
1039	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1245	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1040	ev_periodic_start (loop, &hourly_tick);	1246	ev_periodic_start (loop, &hourly_tick);
1041		1247
1042	Example: the same as above, but use a reschedule callback to do it:	1248	Example: The same as above, but use a reschedule callback to do it:
1043		1249
1044	#include <math.h>	1250	#include <math.h>
1045		1251
1046	static ev_tstamp	1252	static ev_tstamp
1047	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1253	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
1049	return fmod (now, 3600.) + 3600.;	1255	return fmod (now, 3600.) + 3600.;
1050	}	1256	}
1051		1257
1052	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1258	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1053		1259
1054	Example: call a callback every hour, starting now:	1260	Example: Call a callback every hour, starting now:
1055		1261
1056	struct ev_periodic hourly_tick;	1262	struct ev_periodic hourly_tick;
1057	ev_periodic_init (&hourly_tick, clock_cb,	1263	ev_periodic_init (&hourly_tick, clock_cb,
1058	fmod (ev_now (loop), 3600.), 3600., 0);	1264	fmod (ev_now (loop), 3600.), 3600., 0);
1059	ev_periodic_start (loop, &hourly_tick);	1265	ev_periodic_start (loop, &hourly_tick);
…		…
1071	with the kernel (thus it coexists with your own signal handlers as long	1277	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	1278	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	1279	watcher for a signal is stopped libev will reset the signal handler to
1074	SIG_DFL (regardless of what it was set to before).	1280	SIG_DFL (regardless of what it was set to before).
1075		1281
		1282	=head3 Watcher-Specific Functions and Data Members
		1283
1076	=over 4	1284	=over 4
1077		1285
1078	=item ev_signal_init (ev_signal *, callback, int signum)	1286	=item ev_signal_init (ev_signal *, callback, int signum)
1079		1287
1080	=item ev_signal_set (ev_signal *, int signum)	1288	=item ev_signal_set (ev_signal *, int signum)
…		…
1091		1299
1092	=head2 C<ev_child> - watch out for process status changes	1300	=head2 C<ev_child> - watch out for process status changes
1093		1301
1094	Child watchers trigger when your process receives a SIGCHLD in response to	1302	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).	1303	some child status changes (most typically when a child of yours dies).
		1304
		1305	=head3 Watcher-Specific Functions and Data Members
1096		1306
1097	=over 4	1307	=over 4
1098		1308
1099	=item ev_child_init (ev_child *, callback, int pid)	1309	=item ev_child_init (ev_child *, callback, int pid)
1100		1310
…		…
1120	The process exit/trace status caused by C<rpid> (see your systems	1330	The process exit/trace status caused by C<rpid> (see your systems
1121	C<waitpid> and C<sys/wait.h> documentation for details).	1331	C<waitpid> and C<sys/wait.h> documentation for details).
1122		1332
1123	=back	1333	=back
1124		1334
1125	Example: try to exit cleanly on SIGINT and SIGTERM.	1335	Example: Try to exit cleanly on SIGINT and SIGTERM.
1126		1336
1127	static void	1337	static void
1128	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1338	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1129	{	1339	{
1130	ev_unloop (loop, EVUNLOOP_ALL);	1340	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1145	not exist" is a status change like any other. The condition "path does	1355	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	1356	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	1357	otherwise always forced to be at least one) and all the other fields of
1148	the stat buffer having unspecified contents.	1358	the stat buffer having unspecified contents.
1149		1359
		1360	The path I<should> be absolute and I<must not> end in a slash. If it is
		1361	relative and your working directory changes, the behaviour is undefined.
		1362
1150	Since there is no standard to do this, the portable implementation simply	1363	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	1364	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	1365	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,	1366	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	1367	unspecified default> value will be used (which you can expect to be around
1155	five seconds, although this might change dynamically). Libev will also	1368	five seconds, although this might change dynamically). Libev will also
1156	impose a minimum interval which is currently around C<0.1>, but thats	1369	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1158		1371
1159	This watcher type is not meant for massive numbers of stat watchers,	1372	This watcher type is not meant for massive numbers of stat watchers,
1160	as even with OS-supported change notifications, this can be	1373	as even with OS-supported change notifications, this can be
1161	resource-intensive.	1374	resource-intensive.
1162		1375
1163	At the time of this writing, no specific OS backends are implemented, but	1376	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.	1377	implemented (implementing kqueue support is left as an exercise for the
		1378	reader). Inotify will be used to give hints only and should not change the
		1379	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1380	to fall back to regular polling again even with inotify, but changes are
		1381	usually detected immediately, and if the file exists there will be no
		1382	polling.
		1383
		1384	=head3 Watcher-Specific Functions and Data Members
1165		1385
1166	=over 4	1386	=over 4
1167		1387
1168	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1388	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1169		1389
…		…
1233	ev_stat_start (loop, &passwd);	1453	ev_stat_start (loop, &passwd);
1234		1454
1235		1455
1236	=head2 C<ev_idle> - when you've got nothing better to do...	1456	=head2 C<ev_idle> - when you've got nothing better to do...
1237		1457
1238	Idle watchers trigger events when there are no other events are pending	1458	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	1459	priority are pending (prepare, check and other idle watchers do not
1240	as your process is busy handling sockets or timeouts (or even signals,	1460	count).
1241	imagine) it will not be triggered. But when your process is idle all idle	1461
1242	watchers are being called again and again, once per event loop iteration -	1462	That is, as long as your process is busy handling sockets or timeouts
		1463	(or even signals, imagine) of the same or higher priority it will not be
		1464	triggered. But when your process is idle (or only lower-priority watchers
		1465	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	1466	iteration - until stopped, that is, or your process receives more events
1244	busy.	1467	and becomes busy again with higher priority stuff.
1245		1468
1246	The most noteworthy effect is that as long as any idle watchers are	1469	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.	1470	active, the process will not block when waiting for new events.
1248		1471
1249	Apart from keeping your process non-blocking (which is a useful	1472	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	1473	effect on its own sometimes), idle watchers are a good place to do
1251	"pseudo-background processing", or delay processing stuff to after the	1474	"pseudo-background processing", or delay processing stuff to after the
1252	event loop has handled all outstanding events.	1475	event loop has handled all outstanding events.
1253		1476
		1477	=head3 Watcher-Specific Functions and Data Members
		1478
1254	=over 4	1479	=over 4
1255		1480
1256	=item ev_idle_init (ev_signal *, callback)	1481	=item ev_idle_init (ev_signal *, callback)
1257		1482
1258	Initialises and configures the idle watcher - it has no parameters of any	1483	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,	1484	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1260	believe me.	1485	believe me.
1261		1486
1262	=back	1487	=back
1263		1488
1264	Example: dynamically allocate an C<ev_idle>, start it, and in the	1489	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1265	callback, free it. Alos, use no error checking, as usual.	1490	callback, free it. Also, use no error checking, as usual.
1266		1491
1267	static void	1492	static void
1268	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1493	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1269	{	1494	{
1270	free (w);	1495	free (w);
…		…
1315	with priority higher than or equal to the event loop and one coroutine	1540	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	1541	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	1542	loop from blocking if lower-priority coroutines are active, thus mapping
1318	low-priority coroutines to idle/background tasks).	1543	low-priority coroutines to idle/background tasks).
1319		1544
		1545	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1546	priority, to ensure that they are being run before any other watchers
		1547	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1548	too) should not activate ("feed") events into libev. While libev fully
		1549	supports this, they will be called before other C<ev_check> watchers did
		1550	their job. As C<ev_check> watchers are often used to embed other event
		1551	loops those other event loops might be in an unusable state until their
		1552	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1553	others).
		1554
		1555	=head3 Watcher-Specific Functions and Data Members
		1556
1320	=over 4	1557	=over 4
1321		1558
1322	=item ev_prepare_init (ev_prepare *, callback)	1559	=item ev_prepare_init (ev_prepare *, callback)
1323		1560
1324	=item ev_check_init (ev_check *, callback)	1561	=item ev_check_init (ev_check *, callback)
…		…
1327	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1564	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.	1565	macros, but using them is utterly, utterly and completely pointless.
1329		1566
1330	=back	1567	=back
1331		1568
1332	Example: To include a library such as adns, you would add IO watchers	1569	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	1570	into libev. Here are some ideas on how to include libadns into libev
		1571	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1572	use for an actually working example. Another Perl module named C<EV::Glib>
		1573	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1574	into the Glib event loop).
		1575
		1576	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	1577	and in a check watcher, destroy them and call into libadns. What follows
1335	pseudo-code only of course:	1578	is pseudo-code only of course. This requires you to either use a low
		1579	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1580	the callbacks for the IO/timeout watchers might not have been called yet.
1336		1581
1337	static ev_io iow [nfd];	1582	static ev_io iow [nfd];
1338	static ev_timer tw;	1583	static ev_timer tw;
1339		1584
1340	static void	1585	static void
1341	io_cb (ev_loop loop, ev_io w, int revents)	1586	io_cb (ev_loop loop, ev_io w, int revents)
1342	{	1587	{
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	}	1588	}
1349		1589
1350	// create io watchers for each fd and a timer before blocking	1590	// create io watchers for each fd and a timer before blocking
1351	static void	1591	static void
1352	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1592	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1353	{	1593	{
1354	int timeout = 3600000;truct pollfd fds [nfd];	1594	int timeout = 3600000;
		1595	struct pollfd fds [nfd];
1355	// actual code will need to loop here and realloc etc.	1596	// actual code will need to loop here and realloc etc.
1356	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1597	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1357		1598
1358	/* the callback is illegal, but won't be called as we stop during check */	1599	/* the callback is illegal, but won't be called as we stop during check */
1359	ev_timer_init (&tw, 0, timeout * 1e-3);	1600	ev_timer_init (&tw, 0, timeout * 1e-3);
1360	ev_timer_start (loop, &tw);	1601	ev_timer_start (loop, &tw);
1361		1602
1362	// create on ev_io per pollfd	1603	// create one ev_io per pollfd
1363	for (int i = 0; i < nfd; ++i)	1604	for (int i = 0; i < nfd; ++i)
1364	{	1605	{
1365	ev_io_init (iow + i, io_cb, fds [i].fd,	1606	ev_io_init (iow + i, io_cb, fds [i].fd,
1366	((fds [i].events & POLLIN ? EV_READ : 0)	1607	((fds [i].events & POLLIN ? EV_READ : 0)
1367	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1608	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1368		1609
1369	fds [i].revents = 0;	1610	fds [i].revents = 0;
1370	iow [i].data = fds + i;
1371	ev_io_start (loop, iow + i);	1611	ev_io_start (loop, iow + i);
1372	}	1612	}
1373	}	1613	}
1374		1614
1375	// stop all watchers after blocking	1615	// stop all watchers after blocking
…		…
1377	adns_check_cb (ev_loop loop, ev_check w, int revents)	1617	adns_check_cb (ev_loop loop, ev_check w, int revents)
1378	{	1618	{
1379	ev_timer_stop (loop, &tw);	1619	ev_timer_stop (loop, &tw);
1380		1620
1381	for (int i = 0; i < nfd; ++i)	1621	for (int i = 0; i < nfd; ++i)
		1622	{
		1623	// set the relevant poll flags
		1624	// could also call adns_processreadable etc. here
		1625	struct pollfd *fd = fds + i;
		1626	int revents = ev_clear_pending (iow + i);
		1627	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1628	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1629
		1630	// now stop the watcher
1382	ev_io_stop (loop, iow + i);	1631	ev_io_stop (loop, iow + i);
		1632	}
1383		1633
1384	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1634	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1635	}
		1636
		1637	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1638	in the prepare watcher and would dispose of the check watcher.
		1639
		1640	Method 3: If the module to be embedded supports explicit event
		1641	notification (adns does), you can also make use of the actual watcher
		1642	callbacks, and only destroy/create the watchers in the prepare watcher.
		1643
		1644	static void
		1645	timer_cb (EV_P_ ev_timer *w, int revents)
		1646	{
		1647	adns_state ads = (adns_state)w->data;
		1648	update_now (EV_A);
		1649
		1650	adns_processtimeouts (ads, &tv_now);
		1651	}
		1652
		1653	static void
		1654	io_cb (EV_P_ ev_io *w, int revents)
		1655	{
		1656	adns_state ads = (adns_state)w->data;
		1657	update_now (EV_A);
		1658
		1659	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1660	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1661	}
		1662
		1663	// do not ever call adns_afterpoll
		1664
		1665	Method 4: Do not use a prepare or check watcher because the module you
		1666	want to embed is too inflexible to support it. Instead, youc na override
		1667	their poll function. The drawback with this solution is that the main
		1668	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1669	this.
		1670
		1671	static gint
		1672	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1673	{
		1674	int got_events = 0;
		1675
		1676	for (n = 0; n < nfds; ++n)
		1677	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1678
		1679	if (timeout >= 0)
		1680	// create/start timer
		1681
		1682	// poll
		1683	ev_loop (EV_A_ 0);
		1684
		1685	// stop timer again
		1686	if (timeout >= 0)
		1687	ev_timer_stop (EV_A_ &to);
		1688
		1689	// stop io watchers again - their callbacks should have set
		1690	for (n = 0; n < nfds; ++n)
		1691	ev_io_stop (EV_A_ iow [n]);
		1692
		1693	return got_events;
1385	}	1694	}
1386		1695
1387		1696
1388	=head2 C<ev_embed> - when one backend isn't enough...	1697	=head2 C<ev_embed> - when one backend isn't enough...
1389		1698
…		…
1453	ev_embed_start (loop_hi, &embed);	1762	ev_embed_start (loop_hi, &embed);
1454	}	1763	}
1455	else	1764	else
1456	loop_lo = loop_hi;	1765	loop_lo = loop_hi;
1457		1766
		1767	=head3 Watcher-Specific Functions and Data Members
		1768
1458	=over 4	1769	=over 4
1459		1770
1460	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)	1771	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)
1461		1772
1462	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)	1773	=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,	1799	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	1800	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	1801	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1491	handlers will be invoked, too, of course.	1802	handlers will be invoked, too, of course.
1492		1803
		1804	=head3 Watcher-Specific Functions and Data Members
		1805
1493	=over 4	1806	=over 4
1494		1807
1495	=item ev_fork_init (ev_signal *, callback)	1808	=item ev_fork_init (ev_signal *, callback)
1496		1809
1497	Initialises and configures the fork watcher - it has no parameters of any	1810	Initialises and configures the fork watcher - it has no parameters of any
…		…
1593		1906
1594	To use it,	1907	To use it,
1595		1908
1596	#include <ev++.h>	1909	#include <ev++.h>
1597		1910
1598	(it is not installed by default). This automatically includes F<ev.h>	1911	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	1912	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.	1913	put into the C<ev> namespace. It should support all the same embedding
		1914	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1601		1915
1602	It should support all the same embedding options as F<ev.h>, most notably	1916	Care has been taken to keep the overhead low. The only data member the C++
1603	C<EV_MULTIPLICITY>.	1917	classes add (compared to plain C-style watchers) is the event loop pointer
		1918	that the watcher is associated with (or no additional members at all if
		1919	you disable C<EV_MULTIPLICITY> when embedding libev).
		1920
		1921	Currently, functions, and static and non-static member functions can be
		1922	used as callbacks. Other types should be easy to add as long as they only
		1923	need one additional pointer for context. If you need support for other
		1924	types of functors please contact the author (preferably after implementing
		1925	it).
1604		1926
1605	Here is a list of things available in the C<ev> namespace:	1927	Here is a list of things available in the C<ev> namespace:
1606		1928
1607	=over 4	1929	=over 4
1608		1930
…		…
1624		1946
1625	All of those classes have these methods:	1947	All of those classes have these methods:
1626		1948
1627	=over 4	1949	=over 4
1628		1950
1629	=item ev::TYPE::TYPE (object , object::method )	1951	=item ev::TYPE::TYPE ()
1630		1952
1631	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1953	=item ev::TYPE::TYPE (struct ev_loop *)
1632		1954
1633	=item ev::TYPE::~TYPE	1955	=item ev::TYPE::~TYPE
1634		1956
1635	The constructor takes a pointer to an object and a method pointer to	1957	The constructor (optionally) takes an event loop to associate the watcher
1636	the event handler callback to call in this class. The constructor calls	1958	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	1959
1638	before starting it. If you do not specify a loop then the constructor	1960	The constructor calls C<ev_init> for you, which means you have to call the
1639	automatically associates the default loop with this watcher.	1961	C<set> method before starting it.
		1962
		1963	It will not set a callback, however: You have to call the templated C<set>
		1964	method to set a callback before you can start the watcher.
		1965
		1966	(The reason why you have to use a method is a limitation in C++ which does
		1967	not allow explicit template arguments for constructors).
1640		1968
1641	The destructor automatically stops the watcher if it is active.	1969	The destructor automatically stops the watcher if it is active.
		1970
		1971	=item w->set<class, &class::method> (object *)
		1972
		1973	This method sets the callback method to call. The method has to have a
		1974	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1975	first argument and the C<revents> as second. The object must be given as
		1976	parameter and is stored in the C<data> member of the watcher.
		1977
		1978	This method synthesizes efficient thunking code to call your method from
		1979	the C callback that libev requires. If your compiler can inline your
		1980	callback (i.e. it is visible to it at the place of the C<set> call and
		1981	your compiler is good :), then the method will be fully inlined into the
		1982	thunking function, making it as fast as a direct C callback.
		1983
		1984	Example: simple class declaration and watcher initialisation
		1985
		1986	struct myclass
		1987	{
		1988	void io_cb (ev::io &w, int revents) { }
		1989	}
		1990
		1991	myclass obj;
		1992	ev::io iow;
		1993	iow.set <myclass, &myclass::io_cb> (&obj);
		1994
		1995	=item w->set<function> (void *data = 0)
		1996
		1997	Also sets a callback, but uses a static method or plain function as
		1998	callback. The optional C<data> argument will be stored in the watcher's
		1999	C<data> member and is free for you to use.
		2000
		2001	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2002
		2003	See the method-C<set> above for more details.
		2004
		2005	Example:
		2006
		2007	static void io_cb (ev::io &w, int revents) { }
		2008	iow.set <io_cb> ();
1642		2009
1643	=item w->set (struct ev_loop *)	2010	=item w->set (struct ev_loop *)
1644		2011
1645	Associates a different C<struct ev_loop> with this watcher. You can only	2012	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).	2013	do this when the watcher is inactive (and not pending either).
1647		2014
1648	=item w->set ([args])	2015	=item w->set ([args])
1649		2016
1650	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2017	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	2018	called at least once. Unlike the C counterpart, an active watcher gets
1652	automatically stopped and restarted.	2019	automatically stopped and restarted when reconfiguring it with this
		2020	method.
1653		2021
1654	=item w->start ()	2022	=item w->start ()
1655		2023
1656	Starts the watcher. Note that there is no C<loop> argument as the	2024	Starts the watcher. Note that there is no C<loop> argument, as the
1657	constructor already takes the loop.	2025	constructor already stores the event loop.
1658		2026
1659	=item w->stop ()	2027	=item w->stop ()
1660		2028
1661	Stops the watcher if it is active. Again, no C<loop> argument.	2029	Stops the watcher if it is active. Again, no C<loop> argument.
1662		2030
1663	=item w->again () C<ev::timer>, C<ev::periodic> only	2031	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1664		2032
1665	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2033	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1666	C<ev_TYPE_again> function.	2034	C<ev_TYPE_again> function.
1667		2035
1668	=item w->sweep () C<ev::embed> only	2036	=item w->sweep () (C<ev::embed> only)
1669		2037
1670	Invokes C<ev_embed_sweep>.	2038	Invokes C<ev_embed_sweep>.
1671		2039
1672	=item w->update () C<ev::stat> only	2040	=item w->update () (C<ev::stat> only)
1673		2041
1674	Invokes C<ev_stat_stat>.	2042	Invokes C<ev_stat_stat>.
1675		2043
1676	=back	2044	=back
1677		2045
…		…
1687		2055
1688	myclass ();	2056	myclass ();
1689	}	2057	}
1690		2058
1691	myclass::myclass (int fd)	2059	myclass::myclass (int fd)
1692	: io (this, &myclass::io_cb),
1693	idle (this, &myclass::idle_cb)
1694	{	2060	{
		2061	io .set <myclass, &myclass::io_cb > (this);
		2062	idle.set <myclass, &myclass::idle_cb> (this);
		2063
1695	io.start (fd, ev::READ);	2064	io.start (fd, ev::READ);
1696	}	2065	}
1697		2066
1698		2067
1699	=head1 MACRO MAGIC	2068	=head1 MACRO MAGIC
1700		2069
1701	Libev can be compiled with a variety of options, the most fundemantal is	2070	Libev can be compiled with a variety of options, the most fundamantal
1702	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2071	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1703	callbacks have an initial C<struct ev_loop *> argument.	2072	functions and callbacks have an initial C<struct ev_loop *> argument.
1704		2073
1705	To make it easier to write programs that cope with either variant, the	2074	To make it easier to write programs that cope with either variant, the
1706	following macros are defined:	2075	following macros are defined:
1707		2076
1708	=over 4	2077	=over 4
…		…
1740	Similar to the other two macros, this gives you the value of the default	2109	Similar to the other two macros, this gives you the value of the default
1741	loop, if multiple loops are supported ("ev loop default").	2110	loop, if multiple loops are supported ("ev loop default").
1742		2111
1743	=back	2112	=back
1744		2113
1745	Example: Declare and initialise a check watcher, working regardless of	2114	Example: Declare and initialise a check watcher, utilising the above
1746	wether multiple loops are supported or not.	2115	macros so it will work regardless of whether multiple loops are supported
		2116	or not.
1747		2117
1748	static void	2118	static void
1749	check_cb (EV_P_ ev_timer *w, int revents)	2119	check_cb (EV_P_ ev_timer *w, int revents)
1750	{	2120	{
1751	ev_check_stop (EV_A_ w);	2121	ev_check_stop (EV_A_ w);
…		…
1753		2123
1754	ev_check check;	2124	ev_check check;
1755	ev_check_init (&check, check_cb);	2125	ev_check_init (&check, check_cb);
1756	ev_check_start (EV_DEFAULT_ &check);	2126	ev_check_start (EV_DEFAULT_ &check);
1757	ev_loop (EV_DEFAULT_ 0);	2127	ev_loop (EV_DEFAULT_ 0);
1758
1759		2128
1760	=head1 EMBEDDING	2129	=head1 EMBEDDING
1761		2130
1762	Libev can (and often is) directly embedded into host	2131	Libev can (and often is) directly embedded into host
1763	applications. Examples of applications that embed it include the Deliantra	2132	applications. Examples of applications that embed it include the Deliantra
…		…
1803	ev_vars.h	2172	ev_vars.h
1804	ev_wrap.h	2173	ev_wrap.h
1805		2174
1806	ev_win32.c required on win32 platforms only	2175	ev_win32.c required on win32 platforms only
1807		2176
1808	ev_select.c only when select backend is enabled (which is by default)	2177	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)	2178	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)	2179	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)	2180	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)	2181	ev_port.c only when the solaris port backend is enabled (disabled by default)
1813		2182
…		…
1938		2307
1939	=item EV_USE_DEVPOLL	2308	=item EV_USE_DEVPOLL
1940		2309
1941	reserved for future expansion, works like the USE symbols above.	2310	reserved for future expansion, works like the USE symbols above.
1942		2311
		2312	=item EV_USE_INOTIFY
		2313
		2314	If defined to be C<1>, libev will compile in support for the Linux inotify
		2315	interface to speed up C<ev_stat> watchers. Its actual availability will
		2316	be detected at runtime.
		2317
1943	=item EV_H	2318	=item EV_H
1944		2319
1945	The name of the F<ev.h> header file used to include it. The default if	2320	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	2321	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.	2322	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	2345	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	2346	additional independent event loops. Otherwise there will be no support
1972	for multiple event loops and there is no first event loop pointer	2347	for multiple event loops and there is no first event loop pointer
1973	argument. Instead, all functions act on the single default loop.	2348	argument. Instead, all functions act on the single default loop.
1974		2349
		2350	=item EV_MINPRI
		2351
		2352	=item EV_MAXPRI
		2353
		2354	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2355	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2356	provide for more priorities by overriding those symbols (usually defined
		2357	to be C<-2> and C<2>, respectively).
		2358
		2359	When doing priority-based operations, libev usually has to linearly search
		2360	all the priorities, so having many of them (hundreds) uses a lot of space
		2361	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2362	fine.
		2363
		2364	If your embedding app does not need any priorities, defining these both to
		2365	C<0> will save some memory and cpu.
		2366
1975	=item EV_PERIODIC_ENABLE	2367	=item EV_PERIODIC_ENABLE
1976		2368
1977	If undefined or defined to be C<1>, then periodic timers are supported. If	2369	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	2370	defined to be C<0>, then they are not. Disabling them saves a few kB of
1979	code.	2371	code.
1980		2372
		2373	=item EV_IDLE_ENABLE
		2374
		2375	If undefined or defined to be C<1>, then idle watchers are supported. If
		2376	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2377	code.
		2378
1981	=item EV_EMBED_ENABLE	2379	=item EV_EMBED_ENABLE
1982		2380
1983	If undefined or defined to be C<1>, then embed watchers are supported. If	2381	If undefined or defined to be C<1>, then embed watchers are supported. If
1984	defined to be C<0>, then they are not.	2382	defined to be C<0>, then they are not.
1985		2383
…		…
2002	=item EV_PID_HASHSIZE	2400	=item EV_PID_HASHSIZE
2003		2401
2004	C<ev_child> watchers use a small hash table to distribute workload by	2402	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	2403	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	2404	than enough. If you need to manage thousands of children you might want to
2007	increase this value.	2405	increase this value (I<must> be a power of two).
		2406
		2407	=item EV_INOTIFY_HASHSIZE
		2408
		2409	C<ev_staz> watchers use a small hash table to distribute workload by
		2410	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2411	usually more than enough. If you need to manage thousands of C<ev_stat>
		2412	watchers you might want to increase this value (I<must> be a power of
		2413	two).
2008		2414
2009	=item EV_COMMON	2415	=item EV_COMMON
2010		2416
2011	By default, all watchers have a C<void *data> member. By redefining	2417	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	2418	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	2447	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	2448	will be compiled. It is pretty complex because it provides its own header
2043	file.	2449	file.
2044		2450
2045	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2451	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:	2452	that everybody includes and which overrides some configure choices:
2047		2453
		2454	#define EV_MINIMAL 1
2048	#define EV_USE_POLL 0	2455	#define EV_USE_POLL 0
2049	#define EV_MULTIPLICITY 0	2456	#define EV_MULTIPLICITY 0
2050	#define EV_PERIODICS 0	2457	#define EV_PERIODIC_ENABLE 0
		2458	#define EV_STAT_ENABLE 0
		2459	#define EV_FORK_ENABLE 0
2051	#define EV_CONFIG_H <config.h>	2460	#define EV_CONFIG_H <config.h>
		2461	#define EV_MINPRI 0
		2462	#define EV_MAXPRI 0
2052		2463
2053	#include "ev++.h"	2464	#include "ev++.h"
2054		2465
2055	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2466	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2056		2467
…		…
2062		2473
2063	In this section the complexities of (many of) the algorithms used inside	2474	In this section the complexities of (many of) the algorithms used inside
2064	libev will be explained. For complexity discussions about backends see the	2475	libev will be explained. For complexity discussions about backends see the
2065	documentation for C<ev_default_init>.	2476	documentation for C<ev_default_init>.
2066		2477
		2478	All of the following are about amortised time: If an array needs to be
		2479	extended, libev needs to realloc and move the whole array, but this
		2480	happens asymptotically never with higher number of elements, so O(1) might
		2481	mean it might do a lengthy realloc operation in rare cases, but on average
		2482	it is much faster and asymptotically approaches constant time.
		2483
2067	=over 4	2484	=over 4
2068		2485
2069	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2486	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2070		2487
		2488	This means that, when you have a watcher that triggers in one hour and
		2489	there are 100 watchers that would trigger before that then inserting will
		2490	have to skip those 100 watchers.
		2491
2071	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2492	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2072		2493
		2494	That means that for changing a timer costs less than removing/adding them
		2495	as only the relative motion in the event queue has to be paid for.
		2496
2073	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2497	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2074		2498
		2499	These just add the watcher into an array or at the head of a list.
2075	=item Stopping check/prepare/idle watchers: O(1)	2500	=item Stopping check/prepare/idle watchers: O(1)
2076		2501
2077	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2502	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2503
		2504	These watchers are stored in lists then need to be walked to find the
		2505	correct watcher to remove. The lists are usually short (you don't usually
		2506	have many watchers waiting for the same fd or signal).
2078		2507
2079	=item Finding the next timer per loop iteration: O(1)	2508	=item Finding the next timer per loop iteration: O(1)
2080		2509
2081	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2510	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2082		2511
		2512	A change means an I/O watcher gets started or stopped, which requires
		2513	libev to recalculate its status (and possibly tell the kernel).
		2514
2083	=item Activating one watcher: O(1)	2515	=item Activating one watcher: O(1)
2084		2516
		2517	=item Priority handling: O(number_of_priorities)
		2518
		2519	Priorities are implemented by allocating some space for each
		2520	priority. When doing priority-based operations, libev usually has to
		2521	linearly search all the priorities.
		2522
2085	=back	2523	=back
2086		2524
2087		2525
2088	=head1 AUTHOR	2526	=head1 AUTHOR
2089		2527

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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 1.86 by root, Tue Dec 18 01:20:33 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 1.86 by root, Tue Dec 18 01:20:33 2007 UTC