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

Comparing libev/ev.pod (file contents):
Revision 1.51 by root, Tue Nov 27 19:23:31 2007 UTC vs.
Revision 1.78 by root, Sun Dec 9 19:42:57 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
…		…
76	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,
77	as this indicates an incompatible change. Minor versions are usually	129	as this indicates an incompatible change. Minor versions are usually
78	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
79	not a problem.	131	not a problem.
80		132
81	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
82	version:	134	version.
83		135
84	assert (("libev version mismatch",	136	assert (("libev version mismatch",
85	ev_version_major () == EV_VERSION_MAJOR	137	ev_version_major () == EV_VERSION_MAJOR
86	&& ev_version_minor () >= EV_VERSION_MINOR));	138	&& ev_version_minor () >= EV_VERSION_MINOR));
87		139
…		…
117		169
118	See the description of C<ev_embed> watchers for more info.	170	See the description of C<ev_embed> watchers for more info.
119		171
120	=item ev_set_allocator (void (cb)(void *ptr, long size))	172	=item ev_set_allocator (void (cb)(void *ptr, long size))
121		173
122	Sets the allocation function to use (the prototype is similar to the	174	Sets the allocation function to use (the prototype is similar - the
123	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
124	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
125	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
126	destructive action. The default is your system realloc function.	178	potentially destructive action. The default is your system realloc
		179	function.
127		180
128	You could override this function in high-availability programs to, say,	181	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,	182	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.	183	or even to sleep a while and retry until some memory is available.
131		184
132	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
133	retries: better than mine).	186	retries).
134		187
135	static void *	188	static void *
136	persistent_realloc (void *ptr, long size)	189	persistent_realloc (void *ptr, size_t size)
137	{	190	{
138	for (;;)	191	for (;;)
139	{	192	{
140	void *newptr = realloc (ptr, size);	193	void *newptr = realloc (ptr, size);
141		194
…		…
157	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
158	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
159	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
160	(such as abort).	213	(such as abort).
161		214
162	Example: do the same thing as libev does internally:	215	Example: This is basically the same thing that libev does internally, too.
163		216
164	static void	217	static void
165	fatal_error (const char *msg)	218	fatal_error (const char *msg)
166	{	219	{
167	perror (msg);	220	perror (msg);
…		…
217	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	270	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
218	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
219	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
220	around bugs.	273	around bugs.
221		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
222	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	295	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
223		296
224	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
225	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,
226	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
…		…
313	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
314	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
315	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
316	undefined behaviour (or a failed assertion if assertions are enabled).	389	undefined behaviour (or a failed assertion if assertions are enabled).
317		390
318	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.
319		392
320	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	393	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
321	if (!epoller)	394	if (!epoller)
322	fatal ("no epoll found here, maybe it hides under your chair");	395	fatal ("no epoll found here, maybe it hides under your chair");
323		396
…		…
361		434
362	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
363	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
364	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.
365		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.
		448
366	=item unsigned int ev_backend (loop)	449	=item unsigned int ev_backend (loop)
367		450
368	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
369	use.	452	use.
370		453
…		…
403	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	486	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
404	usually a better approach for this kind of thing.	487	usually a better approach for this kind of thing.
405		488
406	Here are the gory details of what C<ev_loop> does:	489	Here are the gory details of what C<ev_loop> does:
407		490
		491	- Before the first iteration, call any pending watchers.
408	* If there are no active watchers (reference count is zero), return.	492	* If there are no active watchers (reference count is zero), return.
409	- Queue prepare watchers and then call all outstanding watchers.	493	- Queue all prepare watchers and then call all outstanding watchers.
410	- If we have been forked, recreate the kernel state.	494	- If we have been forked, recreate the kernel state.
411	- Update the kernel state with all outstanding changes.	495	- Update the kernel state with all outstanding changes.
412	- Update the "event loop time".	496	- Update the "event loop time".
413	- Calculate for how long to block.	497	- Calculate for how long to block.
414	- Block the process, waiting for any events.	498	- Block the process, waiting for any events.
…		…
422	Signals and child watchers are implemented as I/O watchers, and will	506	Signals and child watchers are implemented as I/O watchers, and will
423	be handled here by queueing them when their watcher gets executed.	507	be handled here by queueing them when their watcher gets executed.
424	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	508	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
425	were used, return, otherwise continue with step *.	509	were used, return, otherwise continue with step *.
426		510
427	Example: queue some jobs and then loop until no events are outsanding	511	Example: Queue some jobs and then loop until no events are outsanding
428	anymore.	512	anymore.
429		513
430	... queue jobs here, make sure they register event watchers as long	514	... 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..)	515	... as they still have work to do (even an idle watcher will do..)
432	ev_loop (my_loop, 0);	516	ev_loop (my_loop, 0);
…		…
452	visible to the libev user and should not keep C<ev_loop> from exiting if	536	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	537	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	538	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>.	539	libraries. Just remember to I<unref after start> and I<ref before stop>.
456		540
457	Example: create a signal watcher, but keep it from keeping C<ev_loop>	541	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
458	running when nothing else is active.	542	running when nothing else is active.
459		543
460	struct dv_signal exitsig;	544	struct ev_signal exitsig;
461	ev_signal_init (&exitsig, sig_cb, SIGINT);	545	ev_signal_init (&exitsig, sig_cb, SIGINT);
462	ev_signal_start (myloop, &exitsig);	546	ev_signal_start (loop, &exitsig);
463	evf_unref (myloop);	547	evf_unref (loop);
464		548
465	Example: for some weird reason, unregister the above signal handler again.	549	Example: For some weird reason, unregister the above signal handler again.
466		550
467	ev_ref (myloop);	551	ev_ref (loop);
468	ev_signal_stop (myloop, &exitsig);	552	ev_signal_stop (loop, &exitsig);
469		553
470	=back	554	=back
471		555
472		556
473	=head1 ANATOMY OF A WATCHER	557	=head1 ANATOMY OF A WATCHER
…		…
653	=item bool ev_is_pending (ev_TYPE *watcher)	737	=item bool ev_is_pending (ev_TYPE *watcher)
654		738
655	Returns a true value iff the watcher is pending, (i.e. it has outstanding	739	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	740	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	741	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	742	C<ev_TYPE_set> is safe), you must not change its priority, and you must
659	libev (e.g. you cnanot C<free ()> it).	743	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		744	it).
660		745
661	=item callback = ev_cb (ev_TYPE *watcher)	746	=item callback ev_cb (ev_TYPE *watcher)
662		747
663	Returns the callback currently set on the watcher.	748	Returns the callback currently set on the watcher.
664		749
665	=item ev_cb_set (ev_TYPE *watcher, callback)	750	=item ev_cb_set (ev_TYPE *watcher, callback)
666		751
667	Change the callback. You can change the callback at virtually any time	752	Change the callback. You can change the callback at virtually any time
668	(modulo threads).	753	(modulo threads).
		754
		755	=item ev_set_priority (ev_TYPE *watcher, priority)
		756
		757	=item int ev_priority (ev_TYPE *watcher)
		758
		759	Set and query the priority of the watcher. The priority is a small
		760	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		761	(default: C<-2>). Pending watchers with higher priority will be invoked
		762	before watchers with lower priority, but priority will not keep watchers
		763	from being executed (except for C<ev_idle> watchers).
		764
		765	This means that priorities are I<only> used for ordering callback
		766	invocation after new events have been received. This is useful, for
		767	example, to reduce latency after idling, or more often, to bind two
		768	watchers on the same event and make sure one is called first.
		769
		770	If you need to suppress invocation when higher priority events are pending
		771	you need to look at C<ev_idle> watchers, which provide this functionality.
		772
		773	You I<must not> change the priority of a watcher as long as it is active or
		774	pending.
		775
		776	The default priority used by watchers when no priority has been set is
		777	always C<0>, which is supposed to not be too high and not be too low :).
		778
		779	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		780	fine, as long as you do not mind that the priority value you query might
		781	or might not have been adjusted to be within valid range.
		782
		783	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		784
		785	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		786	C<loop> nor C<revents> need to be valid as long as the watcher callback
		787	can deal with that fact.
		788
		789	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		790
		791	If the watcher is pending, this function returns clears its pending status
		792	and returns its C<revents> bitset (as if its callback was invoked). If the
		793	watcher isn't pending it does nothing and returns C<0>.
669		794
670	=back	795	=back
671		796
672		797
673	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	798	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
694	{	819	{
695	struct my_io w = (struct my_io )w_;	820	struct my_io w = (struct my_io )w_;
696	...	821	...
697	}	822	}
698		823
699	More interesting and less C-conformant ways of catsing your callback type	824	More interesting and less C-conformant ways of casting your callback type
700	have been omitted....	825	instead have been omitted.
		826
		827	Another common scenario is having some data structure with multiple
		828	watchers:
		829
		830	struct my_biggy
		831	{
		832	int some_data;
		833	ev_timer t1;
		834	ev_timer t2;
		835	}
		836
		837	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		838	you need to use C<offsetof>:
		839
		840	#include <stddef.h>
		841
		842	static void
		843	t1_cb (EV_P_ struct ev_timer *w, int revents)
		844	{
		845	struct my_biggy big = (struct my_biggy *
		846	(((char *)w) - offsetof (struct my_biggy, t1));
		847	}
		848
		849	static void
		850	t2_cb (EV_P_ struct ev_timer *w, int revents)
		851	{
		852	struct my_biggy big = (struct my_biggy *
		853	(((char *)w) - offsetof (struct my_biggy, t2));
		854	}
701		855
702		856
703	=head1 WATCHER TYPES	857	=head1 WATCHER TYPES
704		858
705	This section describes each watcher in detail, but will not repeat	859	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	904	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.	905	C<EAGAIN> is far preferable to a program hanging until some data arrives.
752		906
753	If you cannot run the fd in non-blocking mode (for example you should not	907	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	908	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	909	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	910	such as poll (fortunately in our Xlib example, Xlib already does this on
757	its own, so its quite safe to use).	911	its own, so its quite safe to use).
758		912
759	=over 4	913	=over 4
760		914
…		…
774		928
775	The events being watched.	929	The events being watched.
776		930
777	=back	931	=back
778		932
779	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	933	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	934	readable, but only once. Since it is likely line-buffered, you could
781	attempt to read a whole line in the callback:	935	attempt to read a whole line in the callback.
782		936
783	static void	937	static void
784	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	938	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
785	{	939	{
786	ev_io_stop (loop, w);	940	ev_io_stop (loop, w);
…		…
838	=item ev_timer_again (loop)	992	=item ev_timer_again (loop)
839		993
840	This will act as if the timer timed out and restart it again if it is	994	This will act as if the timer timed out and restart it again if it is
841	repeating. The exact semantics are:	995	repeating. The exact semantics are:
842		996
		997	If the timer is pending, its pending status is cleared.
		998
843	If the timer is started but nonrepeating, stop it.	999	If the timer is started but nonrepeating, stop it (as if it timed out).
844		1000
845	If the timer is repeating, either start it if necessary (with the repeat	1001	If the timer is repeating, either start it if necessary (with the
846	value), or reset the running timer to the repeat value.	1002	C<repeat> value), or reset the running timer to the C<repeat> value.
847		1003
848	This sounds a bit complicated, but here is a useful and typical	1004	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	1005	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,	1006	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	1007	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	1008	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	1009	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	1010	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	1011	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
856	need be.	1012	automatically restart it if need be.
857		1013
858	You can also ignore the C<after> value and C<ev_timer_start> altogether	1014	That means you can ignore the C<after> value and C<ev_timer_start>
859	and only ever use the C<repeat> value:	1015	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
860		1016
861	ev_timer_init (timer, callback, 0., 5.);	1017	ev_timer_init (timer, callback, 0., 5.);
862	ev_timer_again (loop, timer);	1018	ev_timer_again (loop, timer);
863	...	1019	...
864	timer->again = 17.;	1020	timer->again = 17.;
865	ev_timer_again (loop, timer);	1021	ev_timer_again (loop, timer);
866	...	1022	...
867	timer->again = 10.;	1023	timer->again = 10.;
868	ev_timer_again (loop, timer);	1024	ev_timer_again (loop, timer);
869		1025
870	This is more efficient then stopping/starting the timer eahc time you want	1026	This is more slightly efficient then stopping/starting the timer each time
871	to modify its timeout value.	1027	you want to modify its timeout value.
872		1028
873	=item ev_tstamp repeat [read-write]	1029	=item ev_tstamp repeat [read-write]
874		1030
875	The current C<repeat> value. Will be used each time the watcher times out	1031	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),	1032	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.	1033	which is also when any modifications are taken into account.
878		1034
879	=back	1035	=back
880		1036
881	Example: create a timer that fires after 60 seconds.	1037	Example: Create a timer that fires after 60 seconds.
882		1038
883	static void	1039	static void
884	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	1040	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
885	{	1041	{
886	.. one minute over, w is actually stopped right here	1042	.. one minute over, w is actually stopped right here
…		…
888		1044
889	struct ev_timer mytimer;	1045	struct ev_timer mytimer;
890	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1046	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
891	ev_timer_start (loop, &mytimer);	1047	ev_timer_start (loop, &mytimer);
892		1048
893	Example: create a timeout timer that times out after 10 seconds of	1049	Example: Create a timeout timer that times out after 10 seconds of
894	inactivity.	1050	inactivity.
895		1051
896	static void	1052	static void
897	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1053	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
898	{	1054	{
…		…
918	but on wallclock time (absolute time). You can tell a periodic watcher	1074	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	1075	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 ()	1076	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	1077	+ 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	1078	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	1079	roughly 10 seconds later).
924	again).
925		1080
926	They can also be used to implement vastly more complex timers, such as	1081	They can also be used to implement vastly more complex timers, such as
927	triggering an event on eahc midnight, local time.	1082	triggering an event on each midnight, local time or other, complicated,
		1083	rules.
928		1084
929	As with timers, the callback is guarenteed to be invoked only when the	1085	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	1086	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.	1087	during the same loop iteration then order of execution is undefined.
932		1088
…		…
939	Lots of arguments, lets sort it out... There are basically three modes of	1095	Lots of arguments, lets sort it out... There are basically three modes of
940	operation, and we will explain them from simplest to complex:	1096	operation, and we will explain them from simplest to complex:
941		1097
942	=over 4	1098	=over 4
943		1099
944	=item * absolute timer (interval = reschedule_cb = 0)	1100	=item * absolute timer (at = time, interval = reschedule_cb = 0)
945		1101
946	In this configuration the watcher triggers an event at the wallclock time	1102	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,	1103	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	1104	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.	1105	system time reaches or surpasses this time.
950		1106
951	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1107	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
952		1108
953	In this mode the watcher will always be scheduled to time out at the next	1109	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	1110	C<at + N * interval> time (for some integer N, which can also be negative)
955	of any time jumps.	1111	and then repeat, regardless of any time jumps.
956		1112
957	This can be used to create timers that do not drift with respect to system	1113	This can be used to create timers that do not drift with respect to system
958	time:	1114	time:
959		1115
960	ev_periodic_set (&periodic, 0., 3600., 0);	1116	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
966		1122
967	Another way to think about it (for the mathematically inclined) is that	1123	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	1124	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.	1125	time where C<time = at (mod interval)>, regardless of any time jumps.
970		1126
		1127	For numerical stability it is preferable that the C<at> value is near
		1128	C<ev_now ()> (the current time), but there is no range requirement for
		1129	this value.
		1130
971	=item * manual reschedule mode (reschedule_cb = callback)	1131	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
972		1132
973	In this mode the values for C<interval> and C<at> are both being	1133	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	1134	ignored. Instead, each time the periodic watcher gets scheduled, the
975	reschedule callback will be called with the watcher as first, and the	1135	reschedule callback will be called with the watcher as first, and the
976	current time as second argument.	1136	current time as second argument.
977		1137
978	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1138	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,	1139	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	1140	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
981	starting a prepare watcher).	1141	starting an C<ev_prepare> watcher, which is legal).
982		1142
983	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	1143	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
984	ev_tstamp now)>, e.g.:	1144	ev_tstamp now)>, e.g.:
985		1145
986	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1146	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	1169	Simply stops and restarts the periodic watcher again. This is only useful
1010	when you changed some parameters or the reschedule callback would return	1170	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	1171	a different time than the last time it was called (e.g. in a crond like
1012	program when the crontabs have changed).	1172	program when the crontabs have changed).
1013		1173
		1174	=item ev_tstamp offset [read-write]
		1175
		1176	When repeating, this contains the offset value, otherwise this is the
		1177	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1178
		1179	Can be modified any time, but changes only take effect when the periodic
		1180	timer fires or C<ev_periodic_again> is being called.
		1181
1014	=item ev_tstamp interval [read-write]	1182	=item ev_tstamp interval [read-write]
1015		1183
1016	The current interval value. Can be modified any time, but changes only	1184	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	1185	take effect when the periodic timer fires or C<ev_periodic_again> is being
1018	called.	1186	called.
…		…
1023	switched off. Can be changed any time, but changes only take effect when	1191	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.	1192	the periodic timer fires or C<ev_periodic_again> is being called.
1025		1193
1026	=back	1194	=back
1027		1195
1028	Example: call a callback every hour, or, more precisely, whenever the	1196	Example: Call a callback every hour, or, more precisely, whenever the
1029	system clock is divisible by 3600. The callback invocation times have	1197	system clock is divisible by 3600. The callback invocation times have
1030	potentially a lot of jittering, but good long-term stability.	1198	potentially a lot of jittering, but good long-term stability.
1031		1199
1032	static void	1200	static void
1033	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1201	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
1037		1205
1038	struct ev_periodic hourly_tick;	1206	struct ev_periodic hourly_tick;
1039	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1207	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1040	ev_periodic_start (loop, &hourly_tick);	1208	ev_periodic_start (loop, &hourly_tick);
1041		1209
1042	Example: the same as above, but use a reschedule callback to do it:	1210	Example: The same as above, but use a reschedule callback to do it:
1043		1211
1044	#include <math.h>	1212	#include <math.h>
1045		1213
1046	static ev_tstamp	1214	static ev_tstamp
1047	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1215	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
1049	return fmod (now, 3600.) + 3600.;	1217	return fmod (now, 3600.) + 3600.;
1050	}	1218	}
1051		1219
1052	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1220	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1053		1221
1054	Example: call a callback every hour, starting now:	1222	Example: Call a callback every hour, starting now:
1055		1223
1056	struct ev_periodic hourly_tick;	1224	struct ev_periodic hourly_tick;
1057	ev_periodic_init (&hourly_tick, clock_cb,	1225	ev_periodic_init (&hourly_tick, clock_cb,
1058	fmod (ev_now (loop), 3600.), 3600., 0);	1226	fmod (ev_now (loop), 3600.), 3600., 0);
1059	ev_periodic_start (loop, &hourly_tick);	1227	ev_periodic_start (loop, &hourly_tick);
…		…
1120	The process exit/trace status caused by C<rpid> (see your systems	1288	The process exit/trace status caused by C<rpid> (see your systems
1121	C<waitpid> and C<sys/wait.h> documentation for details).	1289	C<waitpid> and C<sys/wait.h> documentation for details).
1122		1290
1123	=back	1291	=back
1124		1292
1125	Example: try to exit cleanly on SIGINT and SIGTERM.	1293	Example: Try to exit cleanly on SIGINT and SIGTERM.
1126		1294
1127	static void	1295	static void
1128	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1296	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1129	{	1297	{
1130	ev_unloop (loop, EVUNLOOP_ALL);	1298	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1145	not exist" is a status change like any other. The condition "path does	1313	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	1314	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	1315	otherwise always forced to be at least one) and all the other fields of
1148	the stat buffer having unspecified contents.	1316	the stat buffer having unspecified contents.
1149		1317
		1318	The path I<should> be absolute and I<must not> end in a slash. If it is
		1319	relative and your working directory changes, the behaviour is undefined.
		1320
1150	Since there is no standard to do this, the portable implementation simply	1321	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	1322	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	1323	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,	1324	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	1325	unspecified default> value will be used (which you can expect to be around
1155	five seconds, although this might change dynamically). Libev will also	1326	five seconds, although this might change dynamically). Libev will also
1156	impose a minimum interval which is currently around C<0.1>, but thats	1327	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1158		1329
1159	This watcher type is not meant for massive numbers of stat watchers,	1330	This watcher type is not meant for massive numbers of stat watchers,
1160	as even with OS-supported change notifications, this can be	1331	as even with OS-supported change notifications, this can be
1161	resource-intensive.	1332	resource-intensive.
1162		1333
1163	At the time of this writing, no specific OS backends are implemented, but	1334	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.	1335	implemented (implementing kqueue support is left as an exercise for the
		1336	reader). Inotify will be used to give hints only and should not change the
		1337	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1338	to fall back to regular polling again even with inotify, but changes are
		1339	usually detected immediately, and if the file exists there will be no
		1340	polling.
1165		1341
1166	=over 4	1342	=over 4
1167		1343
1168	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1344	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1169		1345
…		…
1233	ev_stat_start (loop, &passwd);	1409	ev_stat_start (loop, &passwd);
1234		1410
1235		1411
1236	=head2 C<ev_idle> - when you've got nothing better to do...	1412	=head2 C<ev_idle> - when you've got nothing better to do...
1237		1413
1238	Idle watchers trigger events when there are no other events are pending	1414	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	1415	priority are pending (prepare, check and other idle watchers do not
1240	as your process is busy handling sockets or timeouts (or even signals,	1416	count).
1241	imagine) it will not be triggered. But when your process is idle all idle	1417
1242	watchers are being called again and again, once per event loop iteration -	1418	That is, as long as your process is busy handling sockets or timeouts
		1419	(or even signals, imagine) of the same or higher priority it will not be
		1420	triggered. But when your process is idle (or only lower-priority watchers
		1421	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	1422	iteration - until stopped, that is, or your process receives more events
1244	busy.	1423	and becomes busy again with higher priority stuff.
1245		1424
1246	The most noteworthy effect is that as long as any idle watchers are	1425	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.	1426	active, the process will not block when waiting for new events.
1248		1427
1249	Apart from keeping your process non-blocking (which is a useful	1428	Apart from keeping your process non-blocking (which is a useful
…		…
1259	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1438	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1260	believe me.	1439	believe me.
1261		1440
1262	=back	1441	=back
1263		1442
1264	Example: dynamically allocate an C<ev_idle>, start it, and in the	1443	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1265	callback, free it. Alos, use no error checking, as usual.	1444	callback, free it. Also, use no error checking, as usual.
1266		1445
1267	static void	1446	static void
1268	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1447	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1269	{	1448	{
1270	free (w);	1449	free (w);
…		…
1315	with priority higher than or equal to the event loop and one coroutine	1494	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	1495	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	1496	loop from blocking if lower-priority coroutines are active, thus mapping
1318	low-priority coroutines to idle/background tasks).	1497	low-priority coroutines to idle/background tasks).
1319		1498
		1499	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1500	priority, to ensure that they are being run before any other watchers
		1501	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1502	too) should not activate ("feed") events into libev. While libev fully
		1503	supports this, they will be called before other C<ev_check> watchers did
		1504	their job. As C<ev_check> watchers are often used to embed other event
		1505	loops those other event loops might be in an unusable state until their
		1506	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1507	others).
		1508
1320	=over 4	1509	=over 4
1321		1510
1322	=item ev_prepare_init (ev_prepare *, callback)	1511	=item ev_prepare_init (ev_prepare *, callback)
1323		1512
1324	=item ev_check_init (ev_check *, callback)	1513	=item ev_check_init (ev_check *, callback)
…		…
1327	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1516	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.	1517	macros, but using them is utterly, utterly and completely pointless.
1329		1518
1330	=back	1519	=back
1331		1520
1332	Example: To include a library such as adns, you would add IO watchers	1521	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	1522	into libev. Here are some ideas on how to include libadns into libev
		1523	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1524	use for an actually working example. Another Perl module named C<EV::Glib>
		1525	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1526	into the Glib event loop).
		1527
		1528	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	1529	and in a check watcher, destroy them and call into libadns. What follows
1335	pseudo-code only of course:	1530	is pseudo-code only of course. This requires you to either use a low
		1531	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1532	the callbacks for the IO/timeout watchers might not have been called yet.
1336		1533
1337	static ev_io iow [nfd];	1534	static ev_io iow [nfd];
1338	static ev_timer tw;	1535	static ev_timer tw;
1339		1536
1340	static void	1537	static void
1341	io_cb (ev_loop loop, ev_io w, int revents)	1538	io_cb (ev_loop loop, ev_io w, int revents)
1342	{	1539	{
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	}	1540	}
1349		1541
1350	// create io watchers for each fd and a timer before blocking	1542	// create io watchers for each fd and a timer before blocking
1351	static void	1543	static void
1352	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1544	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1353	{	1545	{
1354	int timeout = 3600000;truct pollfd fds [nfd];	1546	int timeout = 3600000;
		1547	struct pollfd fds [nfd];
1355	// actual code will need to loop here and realloc etc.	1548	// actual code will need to loop here and realloc etc.
1356	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1549	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1357		1550
1358	/* the callback is illegal, but won't be called as we stop during check */	1551	/* the callback is illegal, but won't be called as we stop during check */
1359	ev_timer_init (&tw, 0, timeout * 1e-3);	1552	ev_timer_init (&tw, 0, timeout * 1e-3);
1360	ev_timer_start (loop, &tw);	1553	ev_timer_start (loop, &tw);
1361		1554
1362	// create on ev_io per pollfd	1555	// create one ev_io per pollfd
1363	for (int i = 0; i < nfd; ++i)	1556	for (int i = 0; i < nfd; ++i)
1364	{	1557	{
1365	ev_io_init (iow + i, io_cb, fds [i].fd,	1558	ev_io_init (iow + i, io_cb, fds [i].fd,
1366	((fds [i].events & POLLIN ? EV_READ : 0)	1559	((fds [i].events & POLLIN ? EV_READ : 0)
1367	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1560	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1368		1561
1369	fds [i].revents = 0;	1562	fds [i].revents = 0;
1370	iow [i].data = fds + i;
1371	ev_io_start (loop, iow + i);	1563	ev_io_start (loop, iow + i);
1372	}	1564	}
1373	}	1565	}
1374		1566
1375	// stop all watchers after blocking	1567	// stop all watchers after blocking
…		…
1377	adns_check_cb (ev_loop loop, ev_check w, int revents)	1569	adns_check_cb (ev_loop loop, ev_check w, int revents)
1378	{	1570	{
1379	ev_timer_stop (loop, &tw);	1571	ev_timer_stop (loop, &tw);
1380		1572
1381	for (int i = 0; i < nfd; ++i)	1573	for (int i = 0; i < nfd; ++i)
		1574	{
		1575	// set the relevant poll flags
		1576	// could also call adns_processreadable etc. here
		1577	struct pollfd *fd = fds + i;
		1578	int revents = ev_clear_pending (iow + i);
		1579	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1580	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1581
		1582	// now stop the watcher
1382	ev_io_stop (loop, iow + i);	1583	ev_io_stop (loop, iow + i);
		1584	}
1383		1585
1384	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1586	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1587	}
		1588
		1589	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1590	in the prepare watcher and would dispose of the check watcher.
		1591
		1592	Method 3: If the module to be embedded supports explicit event
		1593	notification (adns does), you can also make use of the actual watcher
		1594	callbacks, and only destroy/create the watchers in the prepare watcher.
		1595
		1596	static void
		1597	timer_cb (EV_P_ ev_timer *w, int revents)
		1598	{
		1599	adns_state ads = (adns_state)w->data;
		1600	update_now (EV_A);
		1601
		1602	adns_processtimeouts (ads, &tv_now);
		1603	}
		1604
		1605	static void
		1606	io_cb (EV_P_ ev_io *w, int revents)
		1607	{
		1608	adns_state ads = (adns_state)w->data;
		1609	update_now (EV_A);
		1610
		1611	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1612	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1613	}
		1614
		1615	// do not ever call adns_afterpoll
		1616
		1617	Method 4: Do not use a prepare or check watcher because the module you
		1618	want to embed is too inflexible to support it. Instead, youc na override
		1619	their poll function. The drawback with this solution is that the main
		1620	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1621	this.
		1622
		1623	static gint
		1624	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1625	{
		1626	int got_events = 0;
		1627
		1628	for (n = 0; n < nfds; ++n)
		1629	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1630
		1631	if (timeout >= 0)
		1632	// create/start timer
		1633
		1634	// poll
		1635	ev_loop (EV_A_ 0);
		1636
		1637	// stop timer again
		1638	if (timeout >= 0)
		1639	ev_timer_stop (EV_A_ &to);
		1640
		1641	// stop io watchers again - their callbacks should have set
		1642	for (n = 0; n < nfds; ++n)
		1643	ev_io_stop (EV_A_ iow [n]);
		1644
		1645	return got_events;
1385	}	1646	}
1386		1647
1387		1648
1388	=head2 C<ev_embed> - when one backend isn't enough...	1649	=head2 C<ev_embed> - when one backend isn't enough...
1389		1650
…		…
1593		1854
1594	To use it,	1855	To use it,
1595		1856
1596	#include <ev++.h>	1857	#include <ev++.h>
1597		1858
1598	(it is not installed by default). This automatically includes F<ev.h>	1859	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	1860	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.	1861	put into the C<ev> namespace. It should support all the same embedding
		1862	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1601		1863
1602	It should support all the same embedding options as F<ev.h>, most notably	1864	Care has been taken to keep the overhead low. The only data member the C++
1603	C<EV_MULTIPLICITY>.	1865	classes add (compared to plain C-style watchers) is the event loop pointer
		1866	that the watcher is associated with (or no additional members at all if
		1867	you disable C<EV_MULTIPLICITY> when embedding libev).
		1868
		1869	Currently, functions, and static and non-static member functions can be
		1870	used as callbacks. Other types should be easy to add as long as they only
		1871	need one additional pointer for context. If you need support for other
		1872	types of functors please contact the author (preferably after implementing
		1873	it).
1604		1874
1605	Here is a list of things available in the C<ev> namespace:	1875	Here is a list of things available in the C<ev> namespace:
1606		1876
1607	=over 4	1877	=over 4
1608		1878
…		…
1624		1894
1625	All of those classes have these methods:	1895	All of those classes have these methods:
1626		1896
1627	=over 4	1897	=over 4
1628		1898
1629	=item ev::TYPE::TYPE (object , object::method )	1899	=item ev::TYPE::TYPE ()
1630		1900
1631	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1901	=item ev::TYPE::TYPE (struct ev_loop *)
1632		1902
1633	=item ev::TYPE::~TYPE	1903	=item ev::TYPE::~TYPE
1634		1904
1635	The constructor takes a pointer to an object and a method pointer to	1905	The constructor (optionally) takes an event loop to associate the watcher
1636	the event handler callback to call in this class. The constructor calls	1906	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	1907
1638	before starting it. If you do not specify a loop then the constructor	1908	The constructor calls C<ev_init> for you, which means you have to call the
1639	automatically associates the default loop with this watcher.	1909	C<set> method before starting it.
		1910
		1911	It will not set a callback, however: You have to call the templated C<set>
		1912	method to set a callback before you can start the watcher.
		1913
		1914	(The reason why you have to use a method is a limitation in C++ which does
		1915	not allow explicit template arguments for constructors).
1640		1916
1641	The destructor automatically stops the watcher if it is active.	1917	The destructor automatically stops the watcher if it is active.
		1918
		1919	=item w->set<class, &class::method> (object *)
		1920
		1921	This method sets the callback method to call. The method has to have a
		1922	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1923	first argument and the C<revents> as second. The object must be given as
		1924	parameter and is stored in the C<data> member of the watcher.
		1925
		1926	This method synthesizes efficient thunking code to call your method from
		1927	the C callback that libev requires. If your compiler can inline your
		1928	callback (i.e. it is visible to it at the place of the C<set> call and
		1929	your compiler is good :), then the method will be fully inlined into the
		1930	thunking function, making it as fast as a direct C callback.
		1931
		1932	Example: simple class declaration and watcher initialisation
		1933
		1934	struct myclass
		1935	{
		1936	void io_cb (ev::io &w, int revents) { }
		1937	}
		1938
		1939	myclass obj;
		1940	ev::io iow;
		1941	iow.set <myclass, &myclass::io_cb> (&obj);
		1942
		1943	=item w->set<function> (void *data = 0)
		1944
		1945	Also sets a callback, but uses a static method or plain function as
		1946	callback. The optional C<data> argument will be stored in the watcher's
		1947	C<data> member and is free for you to use.
		1948
		1949	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		1950
		1951	See the method-C<set> above for more details.
		1952
		1953	Example:
		1954
		1955	static void io_cb (ev::io &w, int revents) { }
		1956	iow.set <io_cb> ();
1642		1957
1643	=item w->set (struct ev_loop *)	1958	=item w->set (struct ev_loop *)
1644		1959
1645	Associates a different C<struct ev_loop> with this watcher. You can only	1960	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).	1961	do this when the watcher is inactive (and not pending either).
1647		1962
1648	=item w->set ([args])	1963	=item w->set ([args])
1649		1964
1650	Basically the same as C<ev_TYPE_set>, with the same args. Must be	1965	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	1966	called at least once. Unlike the C counterpart, an active watcher gets
1652	automatically stopped and restarted.	1967	automatically stopped and restarted when reconfiguring it with this
		1968	method.
1653		1969
1654	=item w->start ()	1970	=item w->start ()
1655		1971
1656	Starts the watcher. Note that there is no C<loop> argument as the	1972	Starts the watcher. Note that there is no C<loop> argument, as the
1657	constructor already takes the loop.	1973	constructor already stores the event loop.
1658		1974
1659	=item w->stop ()	1975	=item w->stop ()
1660		1976
1661	Stops the watcher if it is active. Again, no C<loop> argument.	1977	Stops the watcher if it is active. Again, no C<loop> argument.
1662		1978
…		…
1687		2003
1688	myclass ();	2004	myclass ();
1689	}	2005	}
1690		2006
1691	myclass::myclass (int fd)	2007	myclass::myclass (int fd)
1692	: io (this, &myclass::io_cb),
1693	idle (this, &myclass::idle_cb)
1694	{	2008	{
		2009	io .set <myclass, &myclass::io_cb > (this);
		2010	idle.set <myclass, &myclass::idle_cb> (this);
		2011
1695	io.start (fd, ev::READ);	2012	io.start (fd, ev::READ);
1696	}	2013	}
1697		2014
1698		2015
1699	=head1 MACRO MAGIC	2016	=head1 MACRO MAGIC
1700		2017
1701	Libev can be compiled with a variety of options, the most fundemantal is	2018	Libev can be compiled with a variety of options, the most fundemantal is
1702	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2019	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
1703	callbacks have an initial C<struct ev_loop *> argument.	2020	callbacks have an initial C<struct ev_loop *> argument.
1704		2021
1705	To make it easier to write programs that cope with either variant, the	2022	To make it easier to write programs that cope with either variant, the
1706	following macros are defined:	2023	following macros are defined:
1707		2024
…		…
1740	Similar to the other two macros, this gives you the value of the default	2057	Similar to the other two macros, this gives you the value of the default
1741	loop, if multiple loops are supported ("ev loop default").	2058	loop, if multiple loops are supported ("ev loop default").
1742		2059
1743	=back	2060	=back
1744		2061
1745	Example: Declare and initialise a check watcher, working regardless of	2062	Example: Declare and initialise a check watcher, utilising the above
1746	wether multiple loops are supported or not.	2063	macros so it will work regardless of whether multiple loops are supported
		2064	or not.
1747		2065
1748	static void	2066	static void
1749	check_cb (EV_P_ ev_timer *w, int revents)	2067	check_cb (EV_P_ ev_timer *w, int revents)
1750	{	2068	{
1751	ev_check_stop (EV_A_ w);	2069	ev_check_stop (EV_A_ w);
…		…
1753		2071
1754	ev_check check;	2072	ev_check check;
1755	ev_check_init (&check, check_cb);	2073	ev_check_init (&check, check_cb);
1756	ev_check_start (EV_DEFAULT_ &check);	2074	ev_check_start (EV_DEFAULT_ &check);
1757	ev_loop (EV_DEFAULT_ 0);	2075	ev_loop (EV_DEFAULT_ 0);
1758
1759		2076
1760	=head1 EMBEDDING	2077	=head1 EMBEDDING
1761		2078
1762	Libev can (and often is) directly embedded into host	2079	Libev can (and often is) directly embedded into host
1763	applications. Examples of applications that embed it include the Deliantra	2080	applications. Examples of applications that embed it include the Deliantra
…		…
1803	ev_vars.h	2120	ev_vars.h
1804	ev_wrap.h	2121	ev_wrap.h
1805		2122
1806	ev_win32.c required on win32 platforms only	2123	ev_win32.c required on win32 platforms only
1807		2124
1808	ev_select.c only when select backend is enabled (which is by default)	2125	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)	2126	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)	2127	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)	2128	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)	2129	ev_port.c only when the solaris port backend is enabled (disabled by default)
1813		2130
…		…
1938		2255
1939	=item EV_USE_DEVPOLL	2256	=item EV_USE_DEVPOLL
1940		2257
1941	reserved for future expansion, works like the USE symbols above.	2258	reserved for future expansion, works like the USE symbols above.
1942		2259
		2260	=item EV_USE_INOTIFY
		2261
		2262	If defined to be C<1>, libev will compile in support for the Linux inotify
		2263	interface to speed up C<ev_stat> watchers. Its actual availability will
		2264	be detected at runtime.
		2265
1943	=item EV_H	2266	=item EV_H
1944		2267
1945	The name of the F<ev.h> header file used to include it. The default if	2268	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	2269	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.	2270	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	2293	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	2294	additional independent event loops. Otherwise there will be no support
1972	for multiple event loops and there is no first event loop pointer	2295	for multiple event loops and there is no first event loop pointer
1973	argument. Instead, all functions act on the single default loop.	2296	argument. Instead, all functions act on the single default loop.
1974		2297
		2298	=item EV_MINPRI
		2299
		2300	=item EV_MAXPRI
		2301
		2302	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2303	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2304	provide for more priorities by overriding those symbols (usually defined
		2305	to be C<-2> and C<2>, respectively).
		2306
		2307	When doing priority-based operations, libev usually has to linearly search
		2308	all the priorities, so having many of them (hundreds) uses a lot of space
		2309	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2310	fine.
		2311
		2312	If your embedding app does not need any priorities, defining these both to
		2313	C<0> will save some memory and cpu.
		2314
1975	=item EV_PERIODIC_ENABLE	2315	=item EV_PERIODIC_ENABLE
1976		2316
1977	If undefined or defined to be C<1>, then periodic timers are supported. If	2317	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	2318	defined to be C<0>, then they are not. Disabling them saves a few kB of
1979	code.	2319	code.
1980		2320
		2321	=item EV_IDLE_ENABLE
		2322
		2323	If undefined or defined to be C<1>, then idle watchers are supported. If
		2324	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2325	code.
		2326
1981	=item EV_EMBED_ENABLE	2327	=item EV_EMBED_ENABLE
1982		2328
1983	If undefined or defined to be C<1>, then embed watchers are supported. If	2329	If undefined or defined to be C<1>, then embed watchers are supported. If
1984	defined to be C<0>, then they are not.	2330	defined to be C<0>, then they are not.
1985		2331
…		…
2002	=item EV_PID_HASHSIZE	2348	=item EV_PID_HASHSIZE
2003		2349
2004	C<ev_child> watchers use a small hash table to distribute workload by	2350	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	2351	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	2352	than enough. If you need to manage thousands of children you might want to
2007	increase this value.	2353	increase this value (I<must> be a power of two).
		2354
		2355	=item EV_INOTIFY_HASHSIZE
		2356
		2357	C<ev_staz> watchers use a small hash table to distribute workload by
		2358	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2359	usually more than enough. If you need to manage thousands of C<ev_stat>
		2360	watchers you might want to increase this value (I<must> be a power of
		2361	two).
2008		2362
2009	=item EV_COMMON	2363	=item EV_COMMON
2010		2364
2011	By default, all watchers have a C<void *data> member. By redefining	2365	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	2366	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	2395	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	2396	will be compiled. It is pretty complex because it provides its own header
2043	file.	2397	file.
2044		2398
2045	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2399	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:	2400	that everybody includes and which overrides some configure choices:
2047		2401
		2402	#define EV_MINIMAL 1
2048	#define EV_USE_POLL 0	2403	#define EV_USE_POLL 0
2049	#define EV_MULTIPLICITY 0	2404	#define EV_MULTIPLICITY 0
2050	#define EV_PERIODICS 0	2405	#define EV_PERIODIC_ENABLE 0
		2406	#define EV_STAT_ENABLE 0
		2407	#define EV_FORK_ENABLE 0
2051	#define EV_CONFIG_H <config.h>	2408	#define EV_CONFIG_H <config.h>
		2409	#define EV_MINPRI 0
		2410	#define EV_MAXPRI 0
2052		2411
2053	#include "ev++.h"	2412	#include "ev++.h"
2054		2413
2055	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2414	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2056		2415
…		…
2062		2421
2063	In this section the complexities of (many of) the algorithms used inside	2422	In this section the complexities of (many of) the algorithms used inside
2064	libev will be explained. For complexity discussions about backends see the	2423	libev will be explained. For complexity discussions about backends see the
2065	documentation for C<ev_default_init>.	2424	documentation for C<ev_default_init>.
2066		2425
		2426	All of the following are about amortised time: If an array needs to be
		2427	extended, libev needs to realloc and move the whole array, but this
		2428	happens asymptotically never with higher number of elements, so O(1) might
		2429	mean it might do a lengthy realloc operation in rare cases, but on average
		2430	it is much faster and asymptotically approaches constant time.
		2431
2067	=over 4	2432	=over 4
2068		2433
2069	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2434	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2070		2435
		2436	This means that, when you have a watcher that triggers in one hour and
		2437	there are 100 watchers that would trigger before that then inserting will
		2438	have to skip those 100 watchers.
		2439
2071	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2440	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2072		2441
		2442	That means that for changing a timer costs less than removing/adding them
		2443	as only the relative motion in the event queue has to be paid for.
		2444
2073	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2445	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2074		2446
		2447	These just add the watcher into an array or at the head of a list.
2075	=item Stopping check/prepare/idle watchers: O(1)	2448	=item Stopping check/prepare/idle watchers: O(1)
2076		2449
2077	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2450	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2451
		2452	These watchers are stored in lists then need to be walked to find the
		2453	correct watcher to remove. The lists are usually short (you don't usually
		2454	have many watchers waiting for the same fd or signal).
2078		2455
2079	=item Finding the next timer per loop iteration: O(1)	2456	=item Finding the next timer per loop iteration: O(1)
2080		2457
2081	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2458	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2082		2459
		2460	A change means an I/O watcher gets started or stopped, which requires
		2461	libev to recalculate its status (and possibly tell the kernel).
		2462
2083	=item Activating one watcher: O(1)	2463	=item Activating one watcher: O(1)
2084		2464
		2465	=item Priority handling: O(number_of_priorities)
		2466
		2467	Priorities are implemented by allocating some space for each
		2468	priority. When doing priority-based operations, libev usually has to
		2469	linearly search all the priorities.
		2470
2085	=back	2471	=back
2086		2472
2087		2473
2088	=head1 AUTHOR	2474	=head1 AUTHOR
2089		2475

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Comparing libev/ev.pod (file contents): Revision 1.51 by root, Tue Nov 27 19:23:31 2007 UTC vs. Revision 1.78 by root, Sun Dec 9 19:42:57 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.51 by root, Tue Nov 27 19:23:31 2007 UTC vs.
Revision 1.78 by root, Sun Dec 9 19:42:57 2007 UTC