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

Comparing libev/ev.pod (file contents):
Revision 1.49 by root, Tue Nov 27 08:20:42 2007 UTC vs.
Revision 1.73 by root, Sat Dec 8 03:53:36 2007 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
		9	=head1 EXAMPLE PROGRAM
		10
		11	#include <ev.h>
		12
		13	ev_io stdin_watcher;
		14	ev_timer timeout_watcher;
		15
		16	/* called when data readable on stdin */
		17	static void
		18	stdin_cb (EV_P_ struct ev_io *w, int revents)
		19	{
		20	/* puts ("stdin ready"); */
		21	ev_io_stop (EV_A_ w); /* just a syntax example */
		22	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
		23	}
		24
		25	static void
		26	timeout_cb (EV_P_ struct ev_timer *w, int revents)
		27	{
		28	/* puts ("timeout"); */
		29	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
		30	}
		31
		32	int
		33	main (void)
		34	{
		35	struct ev_loop *loop = ev_default_loop (0);
		36
		37	/* initialise an io watcher, then start it */
		38	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);
		39	ev_io_start (loop, &stdin_watcher);
		40
		41	/* simple non-repeating 5.5 second timeout */
		42	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		43	ev_timer_start (loop, &timeout_watcher);
		44
		45	/* loop till timeout or data ready */
		46	ev_loop (loop, 0);
		47
		48	return 0;
		49	}
		50
9	=head1 DESCRIPTION	51	=head1 DESCRIPTION
		52
		53	The newest version of this document is also available as a html-formatted
		54	web page you might find easier to navigate when reading it for the first
		55	time: L<http://cvs.schmorp.de/libev/ev.html>.
10		56
11	Libev is an event loop: you register interest in certain events (such as a	57	Libev is an event loop: you register interest in certain events (such as a
12	file descriptor being readable or a timeout occuring), and it will manage	58	file descriptor being readable or a timeout occuring), and it will manage
13	these event sources and provide your program with events.	59	these event sources and provide your program with events.
14		60
…		…
21	details of the event, and then hand it over to libev by I<starting> the	67	details of the event, and then hand it over to libev by I<starting> the
22	watcher.	68	watcher.
23		69
24	=head1 FEATURES	70	=head1 FEATURES
25		71
26	Libev supports select, poll, the linux-specific epoll and the bsd-specific	72	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
27	kqueue mechanisms for file descriptor events, relative timers, absolute	73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
28	timers with customised rescheduling, signal events, process status change	74	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
29	events (related to SIGCHLD), and event watchers dealing with the event	75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
30	loop mechanism itself (idle, prepare and check watchers). It also is quite	76	with customised rescheduling (C<ev_periodic>), synchronous signals
		77	(C<ev_signal>), process status change events (C<ev_child>), and event
		78	watchers dealing with the event loop mechanism itself (C<ev_idle>,
		79	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
		80	file watchers (C<ev_stat>) and even limited support for fork events
		81	(C<ev_fork>).
		82
		83	It also is quite fast (see this
31	fast (see this L<benchmark\|http://libev.schmorp.de/bench.html> comparing	84	L<benchmark\|http://libev.schmorp.de/bench.html> comparing it to libevent
32	it to libevent for example).	85	for example).
33		86
34	=head1 CONVENTIONS	87	=head1 CONVENTIONS
35		88
36	Libev is very configurable. In this manual the default configuration	89	Libev is very configurable. In this manual the default configuration will
37	will be described, which supports multiple event loops. For more info	90	be described, which supports multiple event loops. For more info about
38	about various configuration options please have a look at the file	91	various configuration options please have a look at B<EMBED> section in
39	F<README.embed> in the libev distribution. If libev was configured without	92	this manual. If libev was configured without support for multiple event
40	support for multiple event loops, then all functions taking an initial	93	loops, then all functions taking an initial argument of name C<loop>
41	argument of name C<loop> (which is always of type C<struct ev_loop *>)	94	(which is always of type C<struct ev_loop *>) will not have this argument.
42	will not have this argument.
43		95
44	=head1 TIME REPRESENTATION	96	=head1 TIME REPRESENTATION
45		97
46	Libev represents time as a single floating point number, representing the	98	Libev represents time as a single floating point number, representing the
47	(fractional) number of seconds since the (POSIX) epoch (somewhere near	99	(fractional) number of seconds since the (POSIX) epoch (somewhere near
48	the beginning of 1970, details are complicated, don't ask). This type is	100	the beginning of 1970, details are complicated, don't ask). This type is
49	called C<ev_tstamp>, which is what you should use too. It usually aliases	101	called C<ev_tstamp>, which is what you should use too. It usually aliases
50	to the C<double> type in C, and when you need to do any calculations on	102	to the C<double> type in C, and when you need to do any calculations on
51	it, you should treat it as such.	103	it, you should treat it as such.
52		104
53
54	=head1 GLOBAL FUNCTIONS	105	=head1 GLOBAL FUNCTIONS
55		106
56	These functions can be called anytime, even before initialising the	107	These functions can be called anytime, even before initialising the
57	library in any way.	108	library in any way.
58		109
…		…
77	Usually, it's a good idea to terminate if the major versions mismatch,	128	Usually, it's a good idea to terminate if the major versions mismatch,
78	as this indicates an incompatible change. Minor versions are usually	129	as this indicates an incompatible change. Minor versions are usually
79	compatible to older versions, so a larger minor version alone is usually	130	compatible to older versions, so a larger minor version alone is usually
80	not a problem.	131	not a problem.
81		132
82	Example: make sure we haven't accidentally been linked against the wrong	133	Example: Make sure we haven't accidentally been linked against the wrong
83	version:	134	version.
84		135
85	assert (("libev version mismatch",	136	assert (("libev version mismatch",
86	ev_version_major () == EV_VERSION_MAJOR	137	ev_version_major () == EV_VERSION_MAJOR
87	&& ev_version_minor () >= EV_VERSION_MINOR));	138	&& ev_version_minor () >= EV_VERSION_MINOR));
88		139
…		…
118		169
119	See the description of C<ev_embed> watchers for more info.	170	See the description of C<ev_embed> watchers for more info.
120		171
121	=item ev_set_allocator (void (cb)(void *ptr, long size))	172	=item ev_set_allocator (void (cb)(void *ptr, long size))
122		173
123	Sets the allocation function to use (the prototype is similar to the	174	Sets the allocation function to use (the prototype is similar - the
124	realloc C function, the semantics are identical). It is used to allocate	175	semantics is identical - to the realloc C function). It is used to
125	and free memory (no surprises here). If it returns zero when memory	176	allocate and free memory (no surprises here). If it returns zero when
126	needs to be allocated, the library might abort or take some potentially	177	memory needs to be allocated, the library might abort or take some
127	destructive action. The default is your system realloc function.	178	potentially destructive action. The default is your system realloc
		179	function.
128		180
129	You could override this function in high-availability programs to, say,	181	You could override this function in high-availability programs to, say,
130	free some memory if it cannot allocate memory, to use a special allocator,	182	free some memory if it cannot allocate memory, to use a special allocator,
131	or even to sleep a while and retry until some memory is available.	183	or even to sleep a while and retry until some memory is available.
132		184
133	Example: replace the libev allocator with one that waits a bit and then	185	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	186	retries).
135		187
136	static void *	188	static void *
137	persistent_realloc (void *ptr, long size)	189	persistent_realloc (void *ptr, size_t size)
138	{	190	{
139	for (;;)	191	for (;;)
140	{	192	{
141	void *newptr = realloc (ptr, size);	193	void *newptr = realloc (ptr, size);
142		194
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	210	callback is set, then libev will expect it to remedy the sitution, no
159	matter what, when it returns. That is, libev will generally retry the	211	matter what, when it returns. That is, libev will generally retry the
160	requested operation, or, if the condition doesn't go away, do bad stuff	212	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	213	(such as abort).
162		214
163	Example: do the same thing as libev does internally:	215	Example: This is basically the same thing that libev does internally, too.
164		216
165	static void	217	static void
166	fatal_error (const char *msg)	218	fatal_error (const char *msg)
167	{	219	{
168	perror (msg);	220	perror (msg);
…		…
218	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	270	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
219	override the flags completely if it is found in the environment. This is	271	override the flags completely if it is found in the environment. This is
220	useful to try out specific backends to test their performance, or to work	272	useful to try out specific backends to test their performance, or to work
221	around bugs.	273	around bugs.
222		274
		275	=item C<EVFLAG_FORKCHECK>
		276
		277	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		278	a fork, you can also make libev check for a fork in each iteration by
		279	enabling this flag.
		280
		281	This works by calling C<getpid ()> on every iteration of the loop,
		282	and thus this might slow down your event loop if you do a lot of loop
		283	iterations and little real work, but is usually not noticeable (on my
		284	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		285	without a syscall and thus I<very> fast, but my Linux system also has
		286	C<pthread_atfork> which is even faster).
		287
		288	The big advantage of this flag is that you can forget about fork (and
		289	forget about forgetting to tell libev about forking) when you use this
		290	flag.
		291
		292	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		293	environment variable.
		294
223	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	295	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
224		296
225	This is your standard select(2) backend. Not I<completely> standard, as	297	This is your standard select(2) backend. Not I<completely> standard, as
226	libev tries to roll its own fd_set with no limits on the number of fds,	298	libev tries to roll its own fd_set with no limits on the number of fds,
227	but if that fails, expect a fairly low limit on the number of fds when	299	but if that fails, expect a fairly low limit on the number of fds when
…		…
314	Similar to C<ev_default_loop>, but always creates a new event loop that is	386	Similar to C<ev_default_loop>, but always creates a new event loop that is
315	always distinct from the default loop. Unlike the default loop, it cannot	387	always distinct from the default loop. Unlike the default loop, it cannot
316	handle signal and child watchers, and attempts to do so will be greeted by	388	handle signal and child watchers, and attempts to do so will be greeted by
317	undefined behaviour (or a failed assertion if assertions are enabled).	389	undefined behaviour (or a failed assertion if assertions are enabled).
318		390
319	Example: try to create a event loop that uses epoll and nothing else.	391	Example: Try to create a event loop that uses epoll and nothing else.
320		392
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	393	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
322	if (!epoller)	394	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	395	fatal ("no epoll found here, maybe it hides under your chair");
324		396
…		…
361	=item ev_loop_fork (loop)	433	=item ev_loop_fork (loop)
362		434
363	Like C<ev_default_fork>, but acts on an event loop created by	435	Like C<ev_default_fork>, but acts on an event loop created by
364	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	436	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
365	after fork, and how you do this is entirely your own problem.	437	after fork, and how you do this is entirely your own problem.
		438
		439	=item unsigned int ev_loop_count (loop)
		440
		441	Returns the count of loop iterations for the loop, which is identical to
		442	the number of times libev did poll for new events. It starts at C<0> and
		443	happily wraps around with enough iterations.
		444
		445	This value can sometimes be useful as a generation counter of sorts (it
		446	"ticks" the number of loop iterations), as it roughly corresponds with
		447	C<ev_prepare> and C<ev_check> calls.
366		448
367	=item unsigned int ev_backend (loop)	449	=item unsigned int ev_backend (loop)
368		450
369	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	451	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
370	use.	452	use.
…		…
423	Signals and child watchers are implemented as I/O watchers, and will	505	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	506	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	507	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	508	were used, return, otherwise continue with step *.
427		509
428	Example: queue some jobs and then loop until no events are outsanding	510	Example: Queue some jobs and then loop until no events are outsanding
429	anymore.	511	anymore.
430		512
431	... queue jobs here, make sure they register event watchers as long	513	... queue jobs here, make sure they register event watchers as long
432	... as they still have work to do (even an idle watcher will do..)	514	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	515	ev_loop (my_loop, 0);
…		…
453	visible to the libev user and should not keep C<ev_loop> from exiting if	535	visible to the libev user and should not keep C<ev_loop> from exiting if
454	no event watchers registered by it are active. It is also an excellent	536	no event watchers registered by it are active. It is also an excellent
455	way to do this for generic recurring timers or from within third-party	537	way to do this for generic recurring timers or from within third-party
456	libraries. Just remember to I<unref after start> and I<ref before stop>.	538	libraries. Just remember to I<unref after start> and I<ref before stop>.
457		539
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	540	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	541	running when nothing else is active.
460		542
461	struct dv_signal exitsig;	543	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	544	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	545	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	546	evf_unref (loop);
465		547
466	Example: for some weird reason, unregister the above signal handler again.	548	Example: For some weird reason, unregister the above signal handler again.
467		549
468	ev_ref (myloop);	550	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	551	ev_signal_stop (loop, &exitsig);
470		552
471	=back	553	=back
472		554
473		555
474	=head1 ANATOMY OF A WATCHER	556	=head1 ANATOMY OF A WATCHER
…		…
565	received events. Callbacks of both watcher types can start and stop as	647	received events. Callbacks of both watcher types can start and stop as
566	many watchers as they want, and all of them will be taken into account	648	many watchers as they want, and all of them will be taken into account
567	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	649	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
568	C<ev_loop> from blocking).	650	C<ev_loop> from blocking).
569		651
		652	=item C<EV_EMBED>
		653
		654	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		655
		656	=item C<EV_FORK>
		657
		658	The event loop has been resumed in the child process after fork (see
		659	C<ev_fork>).
		660
570	=item C<EV_ERROR>	661	=item C<EV_ERROR>
571		662
572	An unspecified error has occured, the watcher has been stopped. This might	663	An unspecified error has occured, the watcher has been stopped. This might
573	happen because the watcher could not be properly started because libev	664	happen because the watcher could not be properly started because libev
574	ran out of memory, a file descriptor was found to be closed or any other	665	ran out of memory, a file descriptor was found to be closed or any other
…		…
645	=item bool ev_is_pending (ev_TYPE *watcher)	736	=item bool ev_is_pending (ev_TYPE *watcher)
646		737
647	Returns a true value iff the watcher is pending, (i.e. it has outstanding	738	Returns a true value iff the watcher is pending, (i.e. it has outstanding
648	events but its callback has not yet been invoked). As long as a watcher	739	events but its callback has not yet been invoked). As long as a watcher
649	is pending (but not active) you must not call an init function on it (but	740	is pending (but not active) you must not call an init function on it (but
650	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	741	C<ev_TYPE_set> is safe), you must not change its priority, and you must
651	libev (e.g. you cnanot C<free ()> it).	742	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		743	it).
652		744
653	=item callback = ev_cb (ev_TYPE *watcher)	745	=item callback ev_cb (ev_TYPE *watcher)
654		746
655	Returns the callback currently set on the watcher.	747	Returns the callback currently set on the watcher.
656		748
657	=item ev_cb_set (ev_TYPE *watcher, callback)	749	=item ev_cb_set (ev_TYPE *watcher, callback)
658		750
659	Change the callback. You can change the callback at virtually any time	751	Change the callback. You can change the callback at virtually any time
660	(modulo threads).	752	(modulo threads).
		753
		754	=item ev_set_priority (ev_TYPE *watcher, priority)
		755
		756	=item int ev_priority (ev_TYPE *watcher)
		757
		758	Set and query the priority of the watcher. The priority is a small
		759	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		760	(default: C<-2>). Pending watchers with higher priority will be invoked
		761	before watchers with lower priority, but priority will not keep watchers
		762	from being executed (except for C<ev_idle> watchers).
		763
		764	This means that priorities are I<only> used for ordering callback
		765	invocation after new events have been received. This is useful, for
		766	example, to reduce latency after idling, or more often, to bind two
		767	watchers on the same event and make sure one is called first.
		768
		769	If you need to suppress invocation when higher priority events are pending
		770	you need to look at C<ev_idle> watchers, which provide this functionality.
		771
		772	You I<must not> change the priority of a watcher as long as it is active or
		773	pending.
		774
		775	The default priority used by watchers when no priority has been set is
		776	always C<0>, which is supposed to not be too high and not be too low :).
		777
		778	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		779	fine, as long as you do not mind that the priority value you query might
		780	or might not have been adjusted to be within valid range.
661		781
662	=back	782	=back
663		783
664		784
665	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	785	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
686	{	806	{
687	struct my_io w = (struct my_io )w_;	807	struct my_io w = (struct my_io )w_;
688	...	808	...
689	}	809	}
690		810
691	More interesting and less C-conformant ways of catsing your callback type	811	More interesting and less C-conformant ways of casting your callback type
692	have been omitted....	812	instead have been omitted.
		813
		814	Another common scenario is having some data structure with multiple
		815	watchers:
		816
		817	struct my_biggy
		818	{
		819	int some_data;
		820	ev_timer t1;
		821	ev_timer t2;
		822	}
		823
		824	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		825	you need to use C<offsetof>:
		826
		827	#include <stddef.h>
		828
		829	static void
		830	t1_cb (EV_P_ struct ev_timer *w, int revents)
		831	{
		832	struct my_biggy big = (struct my_biggy *
		833	(((char *)w) - offsetof (struct my_biggy, t1));
		834	}
		835
		836	static void
		837	t2_cb (EV_P_ struct ev_timer *w, int revents)
		838	{
		839	struct my_biggy big = (struct my_biggy *
		840	(((char *)w) - offsetof (struct my_biggy, t2));
		841	}
693		842
694		843
695	=head1 WATCHER TYPES	844	=head1 WATCHER TYPES
696		845
697	This section describes each watcher in detail, but will not repeat	846	This section describes each watcher in detail, but will not repeat
…		…
742	it is best to always use non-blocking I/O: An extra C<read>(2) returning	891	it is best to always use non-blocking I/O: An extra C<read>(2) returning
743	C<EAGAIN> is far preferable to a program hanging until some data arrives.	892	C<EAGAIN> is far preferable to a program hanging until some data arrives.
744		893
745	If you cannot run the fd in non-blocking mode (for example you should not	894	If you cannot run the fd in non-blocking mode (for example you should not
746	play around with an Xlib connection), then you have to seperately re-test	895	play around with an Xlib connection), then you have to seperately re-test
747	wether a file descriptor is really ready with a known-to-be good interface	896	whether a file descriptor is really ready with a known-to-be good interface
748	such as poll (fortunately in our Xlib example, Xlib already does this on	897	such as poll (fortunately in our Xlib example, Xlib already does this on
749	its own, so its quite safe to use).	898	its own, so its quite safe to use).
750		899
751	=over 4	900	=over 4
752		901
…		…
766		915
767	The events being watched.	916	The events being watched.
768		917
769	=back	918	=back
770		919
771	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	920	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
772	readable, but only once. Since it is likely line-buffered, you could	921	readable, but only once. Since it is likely line-buffered, you could
773	attempt to read a whole line in the callback:	922	attempt to read a whole line in the callback.
774		923
775	static void	924	static void
776	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	925	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
777	{	926	{
778	ev_io_stop (loop, w);	927	ev_io_stop (loop, w);
…		…
830	=item ev_timer_again (loop)	979	=item ev_timer_again (loop)
831		980
832	This will act as if the timer timed out and restart it again if it is	981	This will act as if the timer timed out and restart it again if it is
833	repeating. The exact semantics are:	982	repeating. The exact semantics are:
834		983
		984	If the timer is pending, its pending status is cleared.
		985
835	If the timer is started but nonrepeating, stop it.	986	If the timer is started but nonrepeating, stop it (as if it timed out).
836		987
837	If the timer is repeating, either start it if necessary (with the repeat	988	If the timer is repeating, either start it if necessary (with the
838	value), or reset the running timer to the repeat value.	989	C<repeat> value), or reset the running timer to the C<repeat> value.
839		990
840	This sounds a bit complicated, but here is a useful and typical	991	This sounds a bit complicated, but here is a useful and typical
841	example: Imagine you have a tcp connection and you want a so-called	992	example: Imagine you have a tcp connection and you want a so-called idle
842	idle timeout, that is, you want to be called when there have been,	993	timeout, that is, you want to be called when there have been, say, 60
843	say, 60 seconds of inactivity on the socket. The easiest way to do	994	seconds of inactivity on the socket. The easiest way to do this is to
844	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling	995	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
845	C<ev_timer_again> each time you successfully read or write some data. If	996	C<ev_timer_again> each time you successfully read or write some data. If
846	you go into an idle state where you do not expect data to travel on the	997	you go into an idle state where you do not expect data to travel on the
847	socket, you can stop the timer, and again will automatically restart it if	998	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
848	need be.	999	automatically restart it if need be.
849		1000
850	You can also ignore the C<after> value and C<ev_timer_start> altogether	1001	That means you can ignore the C<after> value and C<ev_timer_start>
851	and only ever use the C<repeat> value:	1002	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
852		1003
853	ev_timer_init (timer, callback, 0., 5.);	1004	ev_timer_init (timer, callback, 0., 5.);
854	ev_timer_again (loop, timer);	1005	ev_timer_again (loop, timer);
855	...	1006	...
856	timer->again = 17.;	1007	timer->again = 17.;
857	ev_timer_again (loop, timer);	1008	ev_timer_again (loop, timer);
858	...	1009	...
859	timer->again = 10.;	1010	timer->again = 10.;
860	ev_timer_again (loop, timer);	1011	ev_timer_again (loop, timer);
861		1012
862	This is more efficient then stopping/starting the timer eahc time you want	1013	This is more slightly efficient then stopping/starting the timer each time
863	to modify its timeout value.	1014	you want to modify its timeout value.
864		1015
865	=item ev_tstamp repeat [read-write]	1016	=item ev_tstamp repeat [read-write]
866		1017
867	The current C<repeat> value. Will be used each time the watcher times out	1018	The current C<repeat> value. Will be used each time the watcher times out
868	or C<ev_timer_again> is called and determines the next timeout (if any),	1019	or C<ev_timer_again> is called and determines the next timeout (if any),
869	which is also when any modifications are taken into account.	1020	which is also when any modifications are taken into account.
870		1021
871	=back	1022	=back
872		1023
873	Example: create a timer that fires after 60 seconds.	1024	Example: Create a timer that fires after 60 seconds.
874		1025
875	static void	1026	static void
876	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	1027	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
877	{	1028	{
878	.. one minute over, w is actually stopped right here	1029	.. one minute over, w is actually stopped right here
…		…
880		1031
881	struct ev_timer mytimer;	1032	struct ev_timer mytimer;
882	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1033	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
883	ev_timer_start (loop, &mytimer);	1034	ev_timer_start (loop, &mytimer);
884		1035
885	Example: create a timeout timer that times out after 10 seconds of	1036	Example: Create a timeout timer that times out after 10 seconds of
886	inactivity.	1037	inactivity.
887		1038
888	static void	1039	static void
889	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1040	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
890	{	1041	{
…		…
1015	switched off. Can be changed any time, but changes only take effect when	1166	switched off. Can be changed any time, but changes only take effect when
1016	the periodic timer fires or C<ev_periodic_again> is being called.	1167	the periodic timer fires or C<ev_periodic_again> is being called.
1017		1168
1018	=back	1169	=back
1019		1170
1020	Example: call a callback every hour, or, more precisely, whenever the	1171	Example: Call a callback every hour, or, more precisely, whenever the
1021	system clock is divisible by 3600. The callback invocation times have	1172	system clock is divisible by 3600. The callback invocation times have
1022	potentially a lot of jittering, but good long-term stability.	1173	potentially a lot of jittering, but good long-term stability.
1023		1174
1024	static void	1175	static void
1025	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1176	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
1029		1180
1030	struct ev_periodic hourly_tick;	1181	struct ev_periodic hourly_tick;
1031	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1182	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1032	ev_periodic_start (loop, &hourly_tick);	1183	ev_periodic_start (loop, &hourly_tick);
1033		1184
1034	Example: the same as above, but use a reschedule callback to do it:	1185	Example: The same as above, but use a reschedule callback to do it:
1035		1186
1036	#include <math.h>	1187	#include <math.h>
1037		1188
1038	static ev_tstamp	1189	static ev_tstamp
1039	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1190	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
1041	return fmod (now, 3600.) + 3600.;	1192	return fmod (now, 3600.) + 3600.;
1042	}	1193	}
1043		1194
1044	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1195	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1045		1196
1046	Example: call a callback every hour, starting now:	1197	Example: Call a callback every hour, starting now:
1047		1198
1048	struct ev_periodic hourly_tick;	1199	struct ev_periodic hourly_tick;
1049	ev_periodic_init (&hourly_tick, clock_cb,	1200	ev_periodic_init (&hourly_tick, clock_cb,
1050	fmod (ev_now (loop), 3600.), 3600., 0);	1201	fmod (ev_now (loop), 3600.), 3600., 0);
1051	ev_periodic_start (loop, &hourly_tick);	1202	ev_periodic_start (loop, &hourly_tick);
…		…
1112	The process exit/trace status caused by C<rpid> (see your systems	1263	The process exit/trace status caused by C<rpid> (see your systems
1113	C<waitpid> and C<sys/wait.h> documentation for details).	1264	C<waitpid> and C<sys/wait.h> documentation for details).
1114		1265
1115	=back	1266	=back
1116		1267
1117	Example: try to exit cleanly on SIGINT and SIGTERM.	1268	Example: Try to exit cleanly on SIGINT and SIGTERM.
1118		1269
1119	static void	1270	static void
1120	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1271	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1121	{	1272	{
1122	ev_unloop (loop, EVUNLOOP_ALL);	1273	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1137	not exist" is a status change like any other. The condition "path does	1288	not exist" is a status change like any other. The condition "path does
1138	not exist" is signified by the C<st_nlink> field being zero (which is	1289	not exist" is signified by the C<st_nlink> field being zero (which is
1139	otherwise always forced to be at least one) and all the other fields of	1290	otherwise always forced to be at least one) and all the other fields of
1140	the stat buffer having unspecified contents.	1291	the stat buffer having unspecified contents.
1141		1292
		1293	The path I<should> be absolute and I<must not> end in a slash. If it is
		1294	relative and your working directory changes, the behaviour is undefined.
		1295
1142	Since there is no standard to do this, the portable implementation simply	1296	Since there is no standard to do this, the portable implementation simply
1143	calls C<stat (2)> regulalry on the path to see if it changed somehow. You	1297	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1144	can specify a recommended polling interval for this case. If you specify	1298	can specify a recommended polling interval for this case. If you specify
1145	a polling interval of C<0> (highly recommended!) then a I<suitable,	1299	a polling interval of C<0> (highly recommended!) then a I<suitable,
1146	unspecified default> value will be used (which you can expect to be around	1300	unspecified default> value will be used (which you can expect to be around
1147	five seconds, although this might change dynamically). Libev will also	1301	five seconds, although this might change dynamically). Libev will also
1148	impose a minimum interval which is currently around C<0.1>, but thats	1302	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1150		1304
1151	This watcher type is not meant for massive numbers of stat watchers,	1305	This watcher type is not meant for massive numbers of stat watchers,
1152	as even with OS-supported change notifications, this can be	1306	as even with OS-supported change notifications, this can be
1153	resource-intensive.	1307	resource-intensive.
1154		1308
1155	At the time of this writing, no specific OS backends are implemented, but	1309	At the time of this writing, only the Linux inotify interface is
1156	if demand increases, at least a kqueue and inotify backend will be added.	1310	implemented (implementing kqueue support is left as an exercise for the
		1311	reader). Inotify will be used to give hints only and should not change the
		1312	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1313	to fall back to regular polling again even with inotify, but changes are
		1314	usually detected immediately, and if the file exists there will be no
		1315	polling.
1157		1316
1158	=over 4	1317	=over 4
1159		1318
1160	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1319	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1161		1320
…		…
1225	ev_stat_start (loop, &passwd);	1384	ev_stat_start (loop, &passwd);
1226		1385
1227		1386
1228	=head2 C<ev_idle> - when you've got nothing better to do...	1387	=head2 C<ev_idle> - when you've got nothing better to do...
1229		1388
1230	Idle watchers trigger events when there are no other events are pending	1389	Idle watchers trigger events when no other events of the same or higher
1231	(prepare, check and other idle watchers do not count). That is, as long	1390	priority are pending (prepare, check and other idle watchers do not
1232	as your process is busy handling sockets or timeouts (or even signals,	1391	count).
1233	imagine) it will not be triggered. But when your process is idle all idle	1392
1234	watchers are being called again and again, once per event loop iteration -	1393	That is, as long as your process is busy handling sockets or timeouts
		1394	(or even signals, imagine) of the same or higher priority it will not be
		1395	triggered. But when your process is idle (or only lower-priority watchers
		1396	are pending), the idle watchers are being called once per event loop
1235	until stopped, that is, or your process receives more events and becomes	1397	iteration - until stopped, that is, or your process receives more events
1236	busy.	1398	and becomes busy again with higher priority stuff.
1237		1399
1238	The most noteworthy effect is that as long as any idle watchers are	1400	The most noteworthy effect is that as long as any idle watchers are
1239	active, the process will not block when waiting for new events.	1401	active, the process will not block when waiting for new events.
1240		1402
1241	Apart from keeping your process non-blocking (which is a useful	1403	Apart from keeping your process non-blocking (which is a useful
…		…
1251	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1413	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1252	believe me.	1414	believe me.
1253		1415
1254	=back	1416	=back
1255		1417
1256	Example: dynamically allocate an C<ev_idle>, start it, and in the	1418	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1257	callback, free it. Alos, use no error checking, as usual.	1419	callback, free it. Also, use no error checking, as usual.
1258		1420
1259	static void	1421	static void
1260	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1422	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1261	{	1423	{
1262	free (w);	1424	free (w);
…		…
1341		1503
1342	// create io watchers for each fd and a timer before blocking	1504	// create io watchers for each fd and a timer before blocking
1343	static void	1505	static void
1344	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1506	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1345	{	1507	{
1346	int timeout = 3600000;truct pollfd fds [nfd];	1508	int timeout = 3600000;
		1509	struct pollfd fds [nfd];
1347	// actual code will need to loop here and realloc etc.	1510	// actual code will need to loop here and realloc etc.
1348	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1511	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1349		1512
1350	/* the callback is illegal, but won't be called as we stop during check */	1513	/* the callback is illegal, but won't be called as we stop during check */
1351	ev_timer_init (&tw, 0, timeout * 1e-3);	1514	ev_timer_init (&tw, 0, timeout * 1e-3);
…		…
1470	The embedded event loop.	1633	The embedded event loop.
1471		1634
1472	=back	1635	=back
1473		1636
1474		1637
		1638	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1639
		1640	Fork watchers are called when a C<fork ()> was detected (usually because
		1641	whoever is a good citizen cared to tell libev about it by calling
		1642	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1643	event loop blocks next and before C<ev_check> watchers are being called,
		1644	and only in the child after the fork. If whoever good citizen calling
		1645	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1646	handlers will be invoked, too, of course.
		1647
		1648	=over 4
		1649
		1650	=item ev_fork_init (ev_signal *, callback)
		1651
		1652	Initialises and configures the fork watcher - it has no parameters of any
		1653	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1654	believe me.
		1655
		1656	=back
		1657
		1658
1475	=head1 OTHER FUNCTIONS	1659	=head1 OTHER FUNCTIONS
1476		1660
1477	There are some other functions of possible interest. Described. Here. Now.	1661	There are some other functions of possible interest. Described. Here. Now.
1478		1662
1479	=over 4	1663	=over 4
…		…
1564		1748
1565	To use it,	1749	To use it,
1566		1750
1567	#include <ev++.h>	1751	#include <ev++.h>
1568		1752
1569	(it is not installed by default). This automatically includes F<ev.h>	1753	This automatically includes F<ev.h> and puts all of its definitions (many
1570	and puts all of its definitions (many of them macros) into the global	1754	of them macros) into the global namespace. All C++ specific things are
1571	namespace. All C++ specific things are put into the C<ev> namespace.	1755	put into the C<ev> namespace. It should support all the same embedding
		1756	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1572		1757
1573	It should support all the same embedding options as F<ev.h>, most notably	1758	Care has been taken to keep the overhead low. The only data member the C++
1574	C<EV_MULTIPLICITY>.	1759	classes add (compared to plain C-style watchers) is the event loop pointer
		1760	that the watcher is associated with (or no additional members at all if
		1761	you disable C<EV_MULTIPLICITY> when embedding libev).
		1762
		1763	Currently, functions, and static and non-static member functions can be
		1764	used as callbacks. Other types should be easy to add as long as they only
		1765	need one additional pointer for context. If you need support for other
		1766	types of functors please contact the author (preferably after implementing
		1767	it).
1575		1768
1576	Here is a list of things available in the C<ev> namespace:	1769	Here is a list of things available in the C<ev> namespace:
1577		1770
1578	=over 4	1771	=over 4
1579		1772
…		…
1595		1788
1596	All of those classes have these methods:	1789	All of those classes have these methods:
1597		1790
1598	=over 4	1791	=over 4
1599		1792
1600	=item ev::TYPE::TYPE (object , object::method )	1793	=item ev::TYPE::TYPE ()
1601		1794
1602	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1795	=item ev::TYPE::TYPE (struct ev_loop *)
1603		1796
1604	=item ev::TYPE::~TYPE	1797	=item ev::TYPE::~TYPE
1605		1798
1606	The constructor takes a pointer to an object and a method pointer to	1799	The constructor (optionally) takes an event loop to associate the watcher
1607	the event handler callback to call in this class. The constructor calls	1800	with. If it is omitted, it will use C<EV_DEFAULT>.
1608	C<ev_init> for you, which means you have to call the C<set> method	1801
1609	before starting it. If you do not specify a loop then the constructor	1802	The constructor calls C<ev_init> for you, which means you have to call the
1610	automatically associates the default loop with this watcher.	1803	C<set> method before starting it.
		1804
		1805	It will not set a callback, however: You have to call the templated C<set>
		1806	method to set a callback before you can start the watcher.
		1807
		1808	(The reason why you have to use a method is a limitation in C++ which does
		1809	not allow explicit template arguments for constructors).
1611		1810
1612	The destructor automatically stops the watcher if it is active.	1811	The destructor automatically stops the watcher if it is active.
		1812
		1813	=item w->set<class, &class::method> (object *)
		1814
		1815	This method sets the callback method to call. The method has to have a
		1816	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1817	first argument and the C<revents> as second. The object must be given as
		1818	parameter and is stored in the C<data> member of the watcher.
		1819
		1820	This method synthesizes efficient thunking code to call your method from
		1821	the C callback that libev requires. If your compiler can inline your
		1822	callback (i.e. it is visible to it at the place of the C<set> call and
		1823	your compiler is good :), then the method will be fully inlined into the
		1824	thunking function, making it as fast as a direct C callback.
		1825
		1826	Example: simple class declaration and watcher initialisation
		1827
		1828	struct myclass
		1829	{
		1830	void io_cb (ev::io &w, int revents) { }
		1831	}
		1832
		1833	myclass obj;
		1834	ev::io iow;
		1835	iow.set <myclass, &myclass::io_cb> (&obj);
		1836
		1837	=item w->set (void (function)(watcher &w, int), void data = 0)
		1838
		1839	Also sets a callback, but uses a static method or plain function as
		1840	callback. The optional C<data> argument will be stored in the watcher's
		1841	C<data> member and is free for you to use.
		1842
		1843	See the method-C<set> above for more details.
1613		1844
1614	=item w->set (struct ev_loop *)	1845	=item w->set (struct ev_loop *)
1615		1846
1616	Associates a different C<struct ev_loop> with this watcher. You can only	1847	Associates a different C<struct ev_loop> with this watcher. You can only
1617	do this when the watcher is inactive (and not pending either).	1848	do this when the watcher is inactive (and not pending either).
1618		1849
1619	=item w->set ([args])	1850	=item w->set ([args])
1620		1851
1621	Basically the same as C<ev_TYPE_set>, with the same args. Must be	1852	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1622	called at least once. Unlike the C counterpart, an active watcher gets	1853	called at least once. Unlike the C counterpart, an active watcher gets
1623	automatically stopped and restarted.	1854	automatically stopped and restarted when reconfiguring it with this
		1855	method.
1624		1856
1625	=item w->start ()	1857	=item w->start ()
1626		1858
1627	Starts the watcher. Note that there is no C<loop> argument as the	1859	Starts the watcher. Note that there is no C<loop> argument, as the
1628	constructor already takes the loop.	1860	constructor already stores the event loop.
1629		1861
1630	=item w->stop ()	1862	=item w->stop ()
1631		1863
1632	Stops the watcher if it is active. Again, no C<loop> argument.	1864	Stops the watcher if it is active. Again, no C<loop> argument.
1633		1865
…		…
1658		1890
1659	myclass ();	1891	myclass ();
1660	}	1892	}
1661		1893
1662	myclass::myclass (int fd)	1894	myclass::myclass (int fd)
1663	: io (this, &myclass::io_cb),
1664	idle (this, &myclass::idle_cb)
1665	{	1895	{
		1896	io .set <myclass, &myclass::io_cb > (this);
		1897	idle.set <myclass, &myclass::idle_cb> (this);
		1898
1666	io.start (fd, ev::READ);	1899	io.start (fd, ev::READ);
1667	}	1900	}
		1901
		1902
		1903	=head1 MACRO MAGIC
		1904
		1905	Libev can be compiled with a variety of options, the most fundemantal is
		1906	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
		1907	callbacks have an initial C<struct ev_loop *> argument.
		1908
		1909	To make it easier to write programs that cope with either variant, the
		1910	following macros are defined:
		1911
		1912	=over 4
		1913
		1914	=item C<EV_A>, C<EV_A_>
		1915
		1916	This provides the loop I<argument> for functions, if one is required ("ev
		1917	loop argument"). The C<EV_A> form is used when this is the sole argument,
		1918	C<EV_A_> is used when other arguments are following. Example:
		1919
		1920	ev_unref (EV_A);
		1921	ev_timer_add (EV_A_ watcher);
		1922	ev_loop (EV_A_ 0);
		1923
		1924	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		1925	which is often provided by the following macro.
		1926
		1927	=item C<EV_P>, C<EV_P_>
		1928
		1929	This provides the loop I<parameter> for functions, if one is required ("ev
		1930	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		1931	C<EV_P_> is used when other parameters are following. Example:
		1932
		1933	// this is how ev_unref is being declared
		1934	static void ev_unref (EV_P);
		1935
		1936	// this is how you can declare your typical callback
		1937	static void cb (EV_P_ ev_timer *w, int revents)
		1938
		1939	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		1940	suitable for use with C<EV_A>.
		1941
		1942	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		1943
		1944	Similar to the other two macros, this gives you the value of the default
		1945	loop, if multiple loops are supported ("ev loop default").
		1946
		1947	=back
		1948
		1949	Example: Declare and initialise a check watcher, utilising the above
		1950	macros so it will work regardless of whether multiple loops are supported
		1951	or not.
		1952
		1953	static void
		1954	check_cb (EV_P_ ev_timer *w, int revents)
		1955	{
		1956	ev_check_stop (EV_A_ w);
		1957	}
		1958
		1959	ev_check check;
		1960	ev_check_init (&check, check_cb);
		1961	ev_check_start (EV_DEFAULT_ &check);
		1962	ev_loop (EV_DEFAULT_ 0);
1668		1963
1669	=head1 EMBEDDING	1964	=head1 EMBEDDING
1670		1965
1671	Libev can (and often is) directly embedded into host	1966	Libev can (and often is) directly embedded into host
1672	applications. Examples of applications that embed it include the Deliantra	1967	applications. Examples of applications that embed it include the Deliantra
…		…
1712	ev_vars.h	2007	ev_vars.h
1713	ev_wrap.h	2008	ev_wrap.h
1714		2009
1715	ev_win32.c required on win32 platforms only	2010	ev_win32.c required on win32 platforms only
1716		2011
1717	ev_select.c only when select backend is enabled (which is by default)	2012	ev_select.c only when select backend is enabled (which is enabled by default)
1718	ev_poll.c only when poll backend is enabled (disabled by default)	2013	ev_poll.c only when poll backend is enabled (disabled by default)
1719	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2014	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1720	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2015	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1721	ev_port.c only when the solaris port backend is enabled (disabled by default)	2016	ev_port.c only when the solaris port backend is enabled (disabled by default)
1722		2017
…		…
1847		2142
1848	=item EV_USE_DEVPOLL	2143	=item EV_USE_DEVPOLL
1849		2144
1850	reserved for future expansion, works like the USE symbols above.	2145	reserved for future expansion, works like the USE symbols above.
1851		2146
		2147	=item EV_USE_INOTIFY
		2148
		2149	If defined to be C<1>, libev will compile in support for the Linux inotify
		2150	interface to speed up C<ev_stat> watchers. Its actual availability will
		2151	be detected at runtime.
		2152
1852	=item EV_H	2153	=item EV_H
1853		2154
1854	The name of the F<ev.h> header file used to include it. The default if	2155	The name of the F<ev.h> header file used to include it. The default if
1855	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2156	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
1856	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2157	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
1879	will have the C<struct ev_loop *> as first argument, and you can create	2180	will have the C<struct ev_loop *> as first argument, and you can create
1880	additional independent event loops. Otherwise there will be no support	2181	additional independent event loops. Otherwise there will be no support
1881	for multiple event loops and there is no first event loop pointer	2182	for multiple event loops and there is no first event loop pointer
1882	argument. Instead, all functions act on the single default loop.	2183	argument. Instead, all functions act on the single default loop.
1883		2184
		2185	=item EV_MINPRI
		2186
		2187	=item EV_MAXPRI
		2188
		2189	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2190	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2191	provide for more priorities by overriding those symbols (usually defined
		2192	to be C<-2> and C<2>, respectively).
		2193
		2194	When doing priority-based operations, libev usually has to linearly search
		2195	all the priorities, so having many of them (hundreds) uses a lot of space
		2196	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2197	fine.
		2198
		2199	If your embedding app does not need any priorities, defining these both to
		2200	C<0> will save some memory and cpu.
		2201
1884	=item EV_PERIODIC_ENABLE	2202	=item EV_PERIODIC_ENABLE
1885		2203
1886	If undefined or defined to be C<1>, then periodic timers are supported. If	2204	If undefined or defined to be C<1>, then periodic timers are supported. If
1887	defined to be C<0>, then they are not. Disabling them saves a few kB of	2205	defined to be C<0>, then they are not. Disabling them saves a few kB of
1888	code.	2206	code.
1889		2207
		2208	=item EV_IDLE_ENABLE
		2209
		2210	If undefined or defined to be C<1>, then idle watchers are supported. If
		2211	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2212	code.
		2213
1890	=item EV_EMBED_ENABLE	2214	=item EV_EMBED_ENABLE
1891		2215
1892	If undefined or defined to be C<1>, then embed watchers are supported. If	2216	If undefined or defined to be C<1>, then embed watchers are supported. If
1893	defined to be C<0>, then they are not.	2217	defined to be C<0>, then they are not.
1894		2218
1895	=item EV_STAT_ENABLE	2219	=item EV_STAT_ENABLE
1896		2220
1897	If undefined or defined to be C<1>, then stat watchers are supported. If	2221	If undefined or defined to be C<1>, then stat watchers are supported. If
		2222	defined to be C<0>, then they are not.
		2223
		2224	=item EV_FORK_ENABLE
		2225
		2226	If undefined or defined to be C<1>, then fork watchers are supported. If
1898	defined to be C<0>, then they are not.	2227	defined to be C<0>, then they are not.
1899		2228
1900	=item EV_MINIMAL	2229	=item EV_MINIMAL
1901		2230
1902	If you need to shave off some kilobytes of code at the expense of some	2231	If you need to shave off some kilobytes of code at the expense of some
1903	speed, define this symbol to C<1>. Currently only used for gcc to override	2232	speed, define this symbol to C<1>. Currently only used for gcc to override
1904	some inlining decisions, saves roughly 30% codesize of amd64.	2233	some inlining decisions, saves roughly 30% codesize of amd64.
		2234
		2235	=item EV_PID_HASHSIZE
		2236
		2237	C<ev_child> watchers use a small hash table to distribute workload by
		2238	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2239	than enough. If you need to manage thousands of children you might want to
		2240	increase this value (I<must> be a power of two).
		2241
		2242	=item EV_INOTIFY_HASHSIZE
		2243
		2244	C<ev_staz> watchers use a small hash table to distribute workload by
		2245	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2246	usually more than enough. If you need to manage thousands of C<ev_stat>
		2247	watchers you might want to increase this value (I<must> be a power of
		2248	two).
1905		2249
1906	=item EV_COMMON	2250	=item EV_COMMON
1907		2251
1908	By default, all watchers have a C<void *data> member. By redefining	2252	By default, all watchers have a C<void *data> member. By redefining
1909	this macro to a something else you can include more and other types of	2253	this macro to a something else you can include more and other types of
…		…
1938	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2282	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
1939	will be compiled. It is pretty complex because it provides its own header	2283	will be compiled. It is pretty complex because it provides its own header
1940	file.	2284	file.
1941		2285
1942	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2286	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
1943	that everybody includes and which overrides some autoconf choices:	2287	that everybody includes and which overrides some configure choices:
1944		2288
		2289	#define EV_MINIMAL 1
1945	#define EV_USE_POLL 0	2290	#define EV_USE_POLL 0
1946	#define EV_MULTIPLICITY 0	2291	#define EV_MULTIPLICITY 0
1947	#define EV_PERIODICS 0	2292	#define EV_PERIODIC_ENABLE 0
		2293	#define EV_STAT_ENABLE 0
		2294	#define EV_FORK_ENABLE 0
1948	#define EV_CONFIG_H <config.h>	2295	#define EV_CONFIG_H <config.h>
		2296	#define EV_MINPRI 0
		2297	#define EV_MAXPRI 0
1949		2298
1950	#include "ev++.h"	2299	#include "ev++.h"
1951		2300
1952	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2301	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
1953		2302
…		…
1959		2308
1960	In this section the complexities of (many of) the algorithms used inside	2309	In this section the complexities of (many of) the algorithms used inside
1961	libev will be explained. For complexity discussions about backends see the	2310	libev will be explained. For complexity discussions about backends see the
1962	documentation for C<ev_default_init>.	2311	documentation for C<ev_default_init>.
1963		2312
		2313	All of the following are about amortised time: If an array needs to be
		2314	extended, libev needs to realloc and move the whole array, but this
		2315	happens asymptotically never with higher number of elements, so O(1) might
		2316	mean it might do a lengthy realloc operation in rare cases, but on average
		2317	it is much faster and asymptotically approaches constant time.
		2318
1964	=over 4	2319	=over 4
1965		2320
1966	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2321	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
1967		2322
		2323	This means that, when you have a watcher that triggers in one hour and
		2324	there are 100 watchers that would trigger before that then inserting will
		2325	have to skip those 100 watchers.
		2326
1968	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2327	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
1969		2328
		2329	That means that for changing a timer costs less than removing/adding them
		2330	as only the relative motion in the event queue has to be paid for.
		2331
1970	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2332	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
1971		2333
		2334	These just add the watcher into an array or at the head of a list.
1972	=item Stopping check/prepare/idle watchers: O(1)	2335	=item Stopping check/prepare/idle watchers: O(1)
1973		2336
1974	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2337	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2338
		2339	These watchers are stored in lists then need to be walked to find the
		2340	correct watcher to remove. The lists are usually short (you don't usually
		2341	have many watchers waiting for the same fd or signal).
1975		2342
1976	=item Finding the next timer per loop iteration: O(1)	2343	=item Finding the next timer per loop iteration: O(1)
1977		2344
1978	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2345	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
1979		2346
		2347	A change means an I/O watcher gets started or stopped, which requires
		2348	libev to recalculate its status (and possibly tell the kernel).
		2349
1980	=item Activating one watcher: O(1)	2350	=item Activating one watcher: O(1)
1981		2351
		2352	=item Priority handling: O(number_of_priorities)
		2353
		2354	Priorities are implemented by allocating some space for each
		2355	priority. When doing priority-based operations, libev usually has to
		2356	linearly search all the priorities.
		2357
1982	=back	2358	=back
1983		2359
1984		2360
1985	=head1 AUTHOR	2361	=head1 AUTHOR
1986		2362

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Comparing libev/ev.pod (file contents): Revision 1.49 by root, Tue Nov 27 08:20:42 2007 UTC vs. Revision 1.73 by root, Sat Dec 8 03:53:36 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.49 by root, Tue Nov 27 08:20:42 2007 UTC vs.
Revision 1.73 by root, Sat Dec 8 03:53:36 2007 UTC