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

Comparing libev/ev.pod (file contents):
Revision 1.53 by root, Tue Nov 27 20:15:02 2007 UTC vs.
Revision 1.77 by root, Sat Dec 8 22:11:14 2007 UTC

…		…
2		2
3	libev - a high performance full-featured event loop written in C	3	libev - a high performance full-featured event loop written in C
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	/* this is the only header you need */
8	#include <ev.h>	7	#include <ev.h>
9		8
10	/* what follows is a fully working example program */	9	=head1 EXAMPLE PROGRAM
		10
		11	#include <ev.h>
		12
11	ev_io stdin_watcher;	13	ev_io stdin_watcher;
12	ev_timer timeout_watcher;	14	ev_timer timeout_watcher;
13		15
14	/* called when data readable on stdin */	16	/* called when data readable on stdin */
15	static void	17	static void
…		…
45		47
46	return 0;	48	return 0;
47	}	49	}
48		50
49	=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>.
50		56
51	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
52	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
53	these event sources and provide your program with events.	59	these event sources and provide your program with events.
54		60
…		…
61	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
62	watcher.	68	watcher.
63		69
64	=head1 FEATURES	70	=head1 FEATURES
65		71
66	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
67	kqueue mechanisms for file descriptor events, relative timers, absolute	73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
68	timers with customised rescheduling, signal events, process status change	74	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
69	events (related to SIGCHLD), and event watchers dealing with the event	75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
70	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
71	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
72	it to libevent for example).	85	for example).
73		86
74	=head1 CONVENTIONS	87	=head1 CONVENTIONS
75		88
76	Libev is very configurable. In this manual the default configuration	89	Libev is very configurable. In this manual the default configuration will
77	will be described, which supports multiple event loops. For more info	90	be described, which supports multiple event loops. For more info about
78	about various configuration options please have a look at the file	91	various configuration options please have a look at B<EMBED> section in
79	F<README.embed> in the libev distribution. If libev was configured without	92	this manual. If libev was configured without support for multiple event
80	support for multiple event loops, then all functions taking an initial	93	loops, then all functions taking an initial argument of name C<loop>
81	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.
82	will not have this argument.
83		95
84	=head1 TIME REPRESENTATION	96	=head1 TIME REPRESENTATION
85		97
86	Libev represents time as a single floating point number, representing the	98	Libev represents time as a single floating point number, representing the
87	(fractional) number of seconds since the (POSIX) epoch (somewhere near	99	(fractional) number of seconds since the (POSIX) epoch (somewhere near
…		…
116	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,
117	as this indicates an incompatible change. Minor versions are usually	129	as this indicates an incompatible change. Minor versions are usually
118	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
119	not a problem.	131	not a problem.
120		132
121	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
122	version:	134	version.
123		135
124	assert (("libev version mismatch",	136	assert (("libev version mismatch",
125	ev_version_major () == EV_VERSION_MAJOR	137	ev_version_major () == EV_VERSION_MAJOR
126	&& ev_version_minor () >= EV_VERSION_MINOR));	138	&& ev_version_minor () >= EV_VERSION_MINOR));
127		139
…		…
155	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	167	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
156	recommended ones.	168	recommended ones.
157		169
158	See the description of C<ev_embed> watchers for more info.	170	See the description of C<ev_embed> watchers for more info.
159		171
160	=item ev_set_allocator (void (cb)(void *ptr, size_t size))	172	=item ev_set_allocator (void (cb)(void *ptr, long size))
161		173
162	Sets the allocation function to use (the prototype and semantics are	174	Sets the allocation function to use (the prototype is similar - the
163	identical to the realloc C function). It is used to allocate and free	175	semantics is identical - to the realloc C function). It is used to
164	memory (no surprises here). If it returns zero when memory needs to be	176	allocate and free memory (no surprises here). If it returns zero when
165	allocated, the library might abort or take some potentially destructive	177	memory needs to be allocated, the library might abort or take some
166	action. The default is your system realloc function.	178	potentially destructive action. The default is your system realloc
		179	function.
167		180
168	You could override this function in high-availability programs to, say,	181	You could override this function in high-availability programs to, say,
169	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,
170	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.
171		184
172	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
173	retries: better than mine).	186	retries).
174		187
175	static void *	188	static void *
176	persistent_realloc (void *ptr, size_t size)	189	persistent_realloc (void *ptr, size_t size)
177	{	190	{
178	for (;;)	191	for (;;)
…		…
197	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
198	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
199	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
200	(such as abort).	213	(such as abort).
201		214
202	Example: do the same thing as libev does internally:	215	Example: This is basically the same thing that libev does internally, too.
203		216
204	static void	217	static void
205	fatal_error (const char *msg)	218	fatal_error (const char *msg)
206	{	219	{
207	perror (msg);	220	perror (msg);
…		…
257	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	270	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
258	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
259	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
260	around bugs.	273	around bugs.
261		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
262	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	295	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
263		296
264	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
265	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,
266	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
…		…
353	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
354	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
355	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
356	undefined behaviour (or a failed assertion if assertions are enabled).	389	undefined behaviour (or a failed assertion if assertions are enabled).
357		390
358	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.
359		392
360	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	393	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
361	if (!epoller)	394	if (!epoller)
362	fatal ("no epoll found here, maybe it hides under your chair");	395	fatal ("no epoll found here, maybe it hides under your chair");
363		396
…		…
401		434
402	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
403	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
404	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.
405		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
406	=item unsigned int ev_backend (loop)	449	=item unsigned int ev_backend (loop)
407		450
408	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
409	use.	452	use.
410		453
…		…
443	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
444	usually a better approach for this kind of thing.	487	usually a better approach for this kind of thing.
445		488
446	Here are the gory details of what C<ev_loop> does:	489	Here are the gory details of what C<ev_loop> does:
447		490
		491	- Before the first iteration, call any pending watchers.
448	* If there are no active watchers (reference count is zero), return.	492	* If there are no active watchers (reference count is zero), return.
449	- Queue prepare watchers and then call all outstanding watchers.	493	- Queue all prepare watchers and then call all outstanding watchers.
450	- If we have been forked, recreate the kernel state.	494	- If we have been forked, recreate the kernel state.
451	- Update the kernel state with all outstanding changes.	495	- Update the kernel state with all outstanding changes.
452	- Update the "event loop time".	496	- Update the "event loop time".
453	- Calculate for how long to block.	497	- Calculate for how long to block.
454	- Block the process, waiting for any events.	498	- Block the process, waiting for any events.
…		…
462	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
463	be handled here by queueing them when their watcher gets executed.	507	be handled here by queueing them when their watcher gets executed.
464	- 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
465	were used, return, otherwise continue with step *.	509	were used, return, otherwise continue with step *.
466		510
467	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
468	anymore.	512	anymore.
469		513
470	... queue jobs here, make sure they register event watchers as long	514	... queue jobs here, make sure they register event watchers as long
471	... 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..)
472	ev_loop (my_loop, 0);	516	ev_loop (my_loop, 0);
…		…
492	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
493	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
494	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
495	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>.
496		540
497	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>
498	running when nothing else is active.	542	running when nothing else is active.
499		543
500	struct dv_signal exitsig;	544	struct ev_signal exitsig;
501	ev_signal_init (&exitsig, sig_cb, SIGINT);	545	ev_signal_init (&exitsig, sig_cb, SIGINT);
502	ev_signal_start (myloop, &exitsig);	546	ev_signal_start (loop, &exitsig);
503	evf_unref (myloop);	547	evf_unref (loop);
504		548
505	Example: for some weird reason, unregister the above signal handler again.	549	Example: For some weird reason, unregister the above signal handler again.
506		550
507	ev_ref (myloop);	551	ev_ref (loop);
508	ev_signal_stop (myloop, &exitsig);	552	ev_signal_stop (loop, &exitsig);
509		553
510	=back	554	=back
511		555
512		556
513	=head1 ANATOMY OF A WATCHER	557	=head1 ANATOMY OF A WATCHER
…		…
693	=item bool ev_is_pending (ev_TYPE *watcher)	737	=item bool ev_is_pending (ev_TYPE *watcher)
694		738
695	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
696	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
697	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
698	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
699	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).
700		745
701	=item callback = ev_cb (ev_TYPE *watcher)	746	=item callback ev_cb (ev_TYPE *watcher)
702		747
703	Returns the callback currently set on the watcher.	748	Returns the callback currently set on the watcher.
704		749
705	=item ev_cb_set (ev_TYPE *watcher, callback)	750	=item ev_cb_set (ev_TYPE *watcher, callback)
706		751
707	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
708	(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>.
709		794
710	=back	795	=back
711		796
712		797
713	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	798	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
734	{	819	{
735	struct my_io w = (struct my_io )w_;	820	struct my_io w = (struct my_io )w_;
736	...	821	...
737	}	822	}
738		823
739	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
740	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	}
741		855
742		856
743	=head1 WATCHER TYPES	857	=head1 WATCHER TYPES
744		858
745	This section describes each watcher in detail, but will not repeat	859	This section describes each watcher in detail, but will not repeat
…		…
790	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
791	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.
792		906
793	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
794	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
795	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
796	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
797	its own, so its quite safe to use).	911	its own, so its quite safe to use).
798		912
799	=over 4	913	=over 4
800		914
…		…
814		928
815	The events being watched.	929	The events being watched.
816		930
817	=back	931	=back
818		932
819	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
820	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
821	attempt to read a whole line in the callback:	935	attempt to read a whole line in the callback.
822		936
823	static void	937	static void
824	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)
825	{	939	{
826	ev_io_stop (loop, w);	940	ev_io_stop (loop, w);
…		…
878	=item ev_timer_again (loop)	992	=item ev_timer_again (loop)
879		993
880	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
881	repeating. The exact semantics are:	995	repeating. The exact semantics are:
882		996
		997	If the timer is pending, its pending status is cleared.
		998
883	If the timer is started but nonrepeating, stop it.	999	If the timer is started but nonrepeating, stop it (as if it timed out).
884		1000
885	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
886	value), or reset the running timer to the repeat value.	1002	C<repeat> value), or reset the running timer to the C<repeat> value.
887		1003
888	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
889	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
890	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
891	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
892	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
893	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
894	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
895	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
896	need be.	1012	automatically restart it if need be.
897		1013
898	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>
899	and only ever use the C<repeat> value:	1015	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
900		1016
901	ev_timer_init (timer, callback, 0., 5.);	1017	ev_timer_init (timer, callback, 0., 5.);
902	ev_timer_again (loop, timer);	1018	ev_timer_again (loop, timer);
903	...	1019	...
904	timer->again = 17.;	1020	timer->again = 17.;
905	ev_timer_again (loop, timer);	1021	ev_timer_again (loop, timer);
906	...	1022	...
907	timer->again = 10.;	1023	timer->again = 10.;
908	ev_timer_again (loop, timer);	1024	ev_timer_again (loop, timer);
909		1025
910	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
911	to modify its timeout value.	1027	you want to modify its timeout value.
912		1028
913	=item ev_tstamp repeat [read-write]	1029	=item ev_tstamp repeat [read-write]
914		1030
915	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
916	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),
917	which is also when any modifications are taken into account.	1033	which is also when any modifications are taken into account.
918		1034
919	=back	1035	=back
920		1036
921	Example: create a timer that fires after 60 seconds.	1037	Example: Create a timer that fires after 60 seconds.
922		1038
923	static void	1039	static void
924	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)
925	{	1041	{
926	.. one minute over, w is actually stopped right here	1042	.. one minute over, w is actually stopped right here
…		…
928		1044
929	struct ev_timer mytimer;	1045	struct ev_timer mytimer;
930	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1046	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
931	ev_timer_start (loop, &mytimer);	1047	ev_timer_start (loop, &mytimer);
932		1048
933	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
934	inactivity.	1050	inactivity.
935		1051
936	static void	1052	static void
937	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)
938	{	1054	{
…		…
1063	switched off. Can be changed any time, but changes only take effect when	1179	switched off. Can be changed any time, but changes only take effect when
1064	the periodic timer fires or C<ev_periodic_again> is being called.	1180	the periodic timer fires or C<ev_periodic_again> is being called.
1065		1181
1066	=back	1182	=back
1067		1183
1068	Example: call a callback every hour, or, more precisely, whenever the	1184	Example: Call a callback every hour, or, more precisely, whenever the
1069	system clock is divisible by 3600. The callback invocation times have	1185	system clock is divisible by 3600. The callback invocation times have
1070	potentially a lot of jittering, but good long-term stability.	1186	potentially a lot of jittering, but good long-term stability.
1071		1187
1072	static void	1188	static void
1073	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1189	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
1077		1193
1078	struct ev_periodic hourly_tick;	1194	struct ev_periodic hourly_tick;
1079	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1195	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1080	ev_periodic_start (loop, &hourly_tick);	1196	ev_periodic_start (loop, &hourly_tick);
1081		1197
1082	Example: the same as above, but use a reschedule callback to do it:	1198	Example: The same as above, but use a reschedule callback to do it:
1083		1199
1084	#include <math.h>	1200	#include <math.h>
1085		1201
1086	static ev_tstamp	1202	static ev_tstamp
1087	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1203	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
1089	return fmod (now, 3600.) + 3600.;	1205	return fmod (now, 3600.) + 3600.;
1090	}	1206	}
1091		1207
1092	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1208	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1093		1209
1094	Example: call a callback every hour, starting now:	1210	Example: Call a callback every hour, starting now:
1095		1211
1096	struct ev_periodic hourly_tick;	1212	struct ev_periodic hourly_tick;
1097	ev_periodic_init (&hourly_tick, clock_cb,	1213	ev_periodic_init (&hourly_tick, clock_cb,
1098	fmod (ev_now (loop), 3600.), 3600., 0);	1214	fmod (ev_now (loop), 3600.), 3600., 0);
1099	ev_periodic_start (loop, &hourly_tick);	1215	ev_periodic_start (loop, &hourly_tick);
…		…
1160	The process exit/trace status caused by C<rpid> (see your systems	1276	The process exit/trace status caused by C<rpid> (see your systems
1161	C<waitpid> and C<sys/wait.h> documentation for details).	1277	C<waitpid> and C<sys/wait.h> documentation for details).
1162		1278
1163	=back	1279	=back
1164		1280
1165	Example: try to exit cleanly on SIGINT and SIGTERM.	1281	Example: Try to exit cleanly on SIGINT and SIGTERM.
1166		1282
1167	static void	1283	static void
1168	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1284	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1169	{	1285	{
1170	ev_unloop (loop, EVUNLOOP_ALL);	1286	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1185	not exist" is a status change like any other. The condition "path does	1301	not exist" is a status change like any other. The condition "path does
1186	not exist" is signified by the C<st_nlink> field being zero (which is	1302	not exist" is signified by the C<st_nlink> field being zero (which is
1187	otherwise always forced to be at least one) and all the other fields of	1303	otherwise always forced to be at least one) and all the other fields of
1188	the stat buffer having unspecified contents.	1304	the stat buffer having unspecified contents.
1189		1305
		1306	The path I<should> be absolute and I<must not> end in a slash. If it is
		1307	relative and your working directory changes, the behaviour is undefined.
		1308
1190	Since there is no standard to do this, the portable implementation simply	1309	Since there is no standard to do this, the portable implementation simply
1191	calls C<stat (2)> regulalry on the path to see if it changed somehow. You	1310	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1192	can specify a recommended polling interval for this case. If you specify	1311	can specify a recommended polling interval for this case. If you specify
1193	a polling interval of C<0> (highly recommended!) then a I<suitable,	1312	a polling interval of C<0> (highly recommended!) then a I<suitable,
1194	unspecified default> value will be used (which you can expect to be around	1313	unspecified default> value will be used (which you can expect to be around
1195	five seconds, although this might change dynamically). Libev will also	1314	five seconds, although this might change dynamically). Libev will also
1196	impose a minimum interval which is currently around C<0.1>, but thats	1315	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1198		1317
1199	This watcher type is not meant for massive numbers of stat watchers,	1318	This watcher type is not meant for massive numbers of stat watchers,
1200	as even with OS-supported change notifications, this can be	1319	as even with OS-supported change notifications, this can be
1201	resource-intensive.	1320	resource-intensive.
1202		1321
1203	At the time of this writing, no specific OS backends are implemented, but	1322	At the time of this writing, only the Linux inotify interface is
1204	if demand increases, at least a kqueue and inotify backend will be added.	1323	implemented (implementing kqueue support is left as an exercise for the
		1324	reader). Inotify will be used to give hints only and should not change the
		1325	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1326	to fall back to regular polling again even with inotify, but changes are
		1327	usually detected immediately, and if the file exists there will be no
		1328	polling.
1205		1329
1206	=over 4	1330	=over 4
1207		1331
1208	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1332	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1209		1333
…		…
1273	ev_stat_start (loop, &passwd);	1397	ev_stat_start (loop, &passwd);
1274		1398
1275		1399
1276	=head2 C<ev_idle> - when you've got nothing better to do...	1400	=head2 C<ev_idle> - when you've got nothing better to do...
1277		1401
1278	Idle watchers trigger events when there are no other events are pending	1402	Idle watchers trigger events when no other events of the same or higher
1279	(prepare, check and other idle watchers do not count). That is, as long	1403	priority are pending (prepare, check and other idle watchers do not
1280	as your process is busy handling sockets or timeouts (or even signals,	1404	count).
1281	imagine) it will not be triggered. But when your process is idle all idle	1405
1282	watchers are being called again and again, once per event loop iteration -	1406	That is, as long as your process is busy handling sockets or timeouts
		1407	(or even signals, imagine) of the same or higher priority it will not be
		1408	triggered. But when your process is idle (or only lower-priority watchers
		1409	are pending), the idle watchers are being called once per event loop
1283	until stopped, that is, or your process receives more events and becomes	1410	iteration - until stopped, that is, or your process receives more events
1284	busy.	1411	and becomes busy again with higher priority stuff.
1285		1412
1286	The most noteworthy effect is that as long as any idle watchers are	1413	The most noteworthy effect is that as long as any idle watchers are
1287	active, the process will not block when waiting for new events.	1414	active, the process will not block when waiting for new events.
1288		1415
1289	Apart from keeping your process non-blocking (which is a useful	1416	Apart from keeping your process non-blocking (which is a useful
…		…
1299	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1426	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1300	believe me.	1427	believe me.
1301		1428
1302	=back	1429	=back
1303		1430
1304	Example: dynamically allocate an C<ev_idle>, start it, and in the	1431	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1305	callback, free it. Alos, use no error checking, as usual.	1432	callback, free it. Also, use no error checking, as usual.
1306		1433
1307	static void	1434	static void
1308	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1435	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1309	{	1436	{
1310	free (w);	1437	free (w);
…		…
1355	with priority higher than or equal to the event loop and one coroutine	1482	with priority higher than or equal to the event loop and one coroutine
1356	of lower priority, but only once, using idle watchers to keep the event	1483	of lower priority, but only once, using idle watchers to keep the event
1357	loop from blocking if lower-priority coroutines are active, thus mapping	1484	loop from blocking if lower-priority coroutines are active, thus mapping
1358	low-priority coroutines to idle/background tasks).	1485	low-priority coroutines to idle/background tasks).
1359		1486
		1487	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1488	priority, to ensure that they are being run before any other watchers
		1489	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1490	too) should not activate ("feed") events into libev. While libev fully
		1491	supports this, they will be called before other C<ev_check> watchers did
		1492	their job. As C<ev_check> watchers are often used to embed other event
		1493	loops those other event loops might be in an unusable state until their
		1494	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1495	others).
		1496
1360	=over 4	1497	=over 4
1361		1498
1362	=item ev_prepare_init (ev_prepare *, callback)	1499	=item ev_prepare_init (ev_prepare *, callback)
1363		1500
1364	=item ev_check_init (ev_check *, callback)	1501	=item ev_check_init (ev_check *, callback)
…		…
1367	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1504	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1368	macros, but using them is utterly, utterly and completely pointless.	1505	macros, but using them is utterly, utterly and completely pointless.
1369		1506
1370	=back	1507	=back
1371		1508
1372	Example: To include a library such as adns, you would add IO watchers	1509	There are a number of principal ways to embed other event loops or modules
1373	and a timeout watcher in a prepare handler, as required by libadns, and	1510	into libev. Here are some ideas on how to include libadns into libev
		1511	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1512	use for an actually working example. Another Perl module named C<EV::Glib>
		1513	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1514	into the Glib event loop).
		1515
		1516	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1374	in a check watcher, destroy them and call into libadns. What follows is	1517	and in a check watcher, destroy them and call into libadns. What follows
1375	pseudo-code only of course:	1518	is pseudo-code only of course. This requires you to either use a low
		1519	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1520	the callbacks for the IO/timeout watchers might not have been called yet.
1376		1521
1377	static ev_io iow [nfd];	1522	static ev_io iow [nfd];
1378	static ev_timer tw;	1523	static ev_timer tw;
1379		1524
1380	static void	1525	static void
1381	io_cb (ev_loop loop, ev_io w, int revents)	1526	io_cb (ev_loop loop, ev_io w, int revents)
1382	{	1527	{
1383	// set the relevant poll flags
1384	// could also call adns_processreadable etc. here
1385	struct pollfd fd = (struct pollfd )w->data;
1386	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1387	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1388	}	1528	}
1389		1529
1390	// create io watchers for each fd and a timer before blocking	1530	// create io watchers for each fd and a timer before blocking
1391	static void	1531	static void
1392	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1532	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1393	{	1533	{
1394	int timeout = 3600000;truct pollfd fds [nfd];	1534	int timeout = 3600000;
		1535	struct pollfd fds [nfd];
1395	// actual code will need to loop here and realloc etc.	1536	// actual code will need to loop here and realloc etc.
1396	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1537	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1397		1538
1398	/* the callback is illegal, but won't be called as we stop during check */	1539	/* the callback is illegal, but won't be called as we stop during check */
1399	ev_timer_init (&tw, 0, timeout * 1e-3);	1540	ev_timer_init (&tw, 0, timeout * 1e-3);
1400	ev_timer_start (loop, &tw);	1541	ev_timer_start (loop, &tw);
1401		1542
1402	// create on ev_io per pollfd	1543	// create one ev_io per pollfd
1403	for (int i = 0; i < nfd; ++i)	1544	for (int i = 0; i < nfd; ++i)
1404	{	1545	{
1405	ev_io_init (iow + i, io_cb, fds [i].fd,	1546	ev_io_init (iow + i, io_cb, fds [i].fd,
1406	((fds [i].events & POLLIN ? EV_READ : 0)	1547	((fds [i].events & POLLIN ? EV_READ : 0)
1407	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1548	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1408		1549
1409	fds [i].revents = 0;	1550	fds [i].revents = 0;
1410	iow [i].data = fds + i;
1411	ev_io_start (loop, iow + i);	1551	ev_io_start (loop, iow + i);
1412	}	1552	}
1413	}	1553	}
1414		1554
1415	// stop all watchers after blocking	1555	// stop all watchers after blocking
…		…
1417	adns_check_cb (ev_loop loop, ev_check w, int revents)	1557	adns_check_cb (ev_loop loop, ev_check w, int revents)
1418	{	1558	{
1419	ev_timer_stop (loop, &tw);	1559	ev_timer_stop (loop, &tw);
1420		1560
1421	for (int i = 0; i < nfd; ++i)	1561	for (int i = 0; i < nfd; ++i)
		1562	{
		1563	// set the relevant poll flags
		1564	// could also call adns_processreadable etc. here
		1565	struct pollfd *fd = fds + i;
		1566	int revents = ev_clear_pending (iow + i);
		1567	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1568	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1569
		1570	// now stop the watcher
1422	ev_io_stop (loop, iow + i);	1571	ev_io_stop (loop, iow + i);
		1572	}
1423		1573
1424	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1574	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1575	}
		1576
		1577	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1578	in the prepare watcher and would dispose of the check watcher.
		1579
		1580	Method 3: If the module to be embedded supports explicit event
		1581	notification (adns does), you can also make use of the actual watcher
		1582	callbacks, and only destroy/create the watchers in the prepare watcher.
		1583
		1584	static void
		1585	timer_cb (EV_P_ ev_timer *w, int revents)
		1586	{
		1587	adns_state ads = (adns_state)w->data;
		1588	update_now (EV_A);
		1589
		1590	adns_processtimeouts (ads, &tv_now);
		1591	}
		1592
		1593	static void
		1594	io_cb (EV_P_ ev_io *w, int revents)
		1595	{
		1596	adns_state ads = (adns_state)w->data;
		1597	update_now (EV_A);
		1598
		1599	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1600	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1601	}
		1602
		1603	// do not ever call adns_afterpoll
		1604
		1605	Method 4: Do not use a prepare or check watcher because the module you
		1606	want to embed is too inflexible to support it. Instead, youc na override
		1607	their poll function. The drawback with this solution is that the main
		1608	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1609	this.
		1610
		1611	static gint
		1612	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1613	{
		1614	int got_events = 0;
		1615
		1616	for (n = 0; n < nfds; ++n)
		1617	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1618
		1619	if (timeout >= 0)
		1620	// create/start timer
		1621
		1622	// poll
		1623	ev_loop (EV_A_ 0);
		1624
		1625	// stop timer again
		1626	if (timeout >= 0)
		1627	ev_timer_stop (EV_A_ &to);
		1628
		1629	// stop io watchers again - their callbacks should have set
		1630	for (n = 0; n < nfds; ++n)
		1631	ev_io_stop (EV_A_ iow [n]);
		1632
		1633	return got_events;
1425	}	1634	}
1426		1635
1427		1636
1428	=head2 C<ev_embed> - when one backend isn't enough...	1637	=head2 C<ev_embed> - when one backend isn't enough...
1429		1638
…		…
1633		1842
1634	To use it,	1843	To use it,
1635		1844
1636	#include <ev++.h>	1845	#include <ev++.h>
1637		1846
1638	(it is not installed by default). This automatically includes F<ev.h>	1847	This automatically includes F<ev.h> and puts all of its definitions (many
1639	and puts all of its definitions (many of them macros) into the global	1848	of them macros) into the global namespace. All C++ specific things are
1640	namespace. All C++ specific things are put into the C<ev> namespace.	1849	put into the C<ev> namespace. It should support all the same embedding
		1850	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1641		1851
1642	It should support all the same embedding options as F<ev.h>, most notably	1852	Care has been taken to keep the overhead low. The only data member the C++
1643	C<EV_MULTIPLICITY>.	1853	classes add (compared to plain C-style watchers) is the event loop pointer
		1854	that the watcher is associated with (or no additional members at all if
		1855	you disable C<EV_MULTIPLICITY> when embedding libev).
		1856
		1857	Currently, functions, and static and non-static member functions can be
		1858	used as callbacks. Other types should be easy to add as long as they only
		1859	need one additional pointer for context. If you need support for other
		1860	types of functors please contact the author (preferably after implementing
		1861	it).
1644		1862
1645	Here is a list of things available in the C<ev> namespace:	1863	Here is a list of things available in the C<ev> namespace:
1646		1864
1647	=over 4	1865	=over 4
1648		1866
…		…
1664		1882
1665	All of those classes have these methods:	1883	All of those classes have these methods:
1666		1884
1667	=over 4	1885	=over 4
1668		1886
1669	=item ev::TYPE::TYPE (object , object::method )	1887	=item ev::TYPE::TYPE ()
1670		1888
1671	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1889	=item ev::TYPE::TYPE (struct ev_loop *)
1672		1890
1673	=item ev::TYPE::~TYPE	1891	=item ev::TYPE::~TYPE
1674		1892
1675	The constructor takes a pointer to an object and a method pointer to	1893	The constructor (optionally) takes an event loop to associate the watcher
1676	the event handler callback to call in this class. The constructor calls	1894	with. If it is omitted, it will use C<EV_DEFAULT>.
1677	C<ev_init> for you, which means you have to call the C<set> method	1895
1678	before starting it. If you do not specify a loop then the constructor	1896	The constructor calls C<ev_init> for you, which means you have to call the
1679	automatically associates the default loop with this watcher.	1897	C<set> method before starting it.
		1898
		1899	It will not set a callback, however: You have to call the templated C<set>
		1900	method to set a callback before you can start the watcher.
		1901
		1902	(The reason why you have to use a method is a limitation in C++ which does
		1903	not allow explicit template arguments for constructors).
1680		1904
1681	The destructor automatically stops the watcher if it is active.	1905	The destructor automatically stops the watcher if it is active.
		1906
		1907	=item w->set<class, &class::method> (object *)
		1908
		1909	This method sets the callback method to call. The method has to have a
		1910	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1911	first argument and the C<revents> as second. The object must be given as
		1912	parameter and is stored in the C<data> member of the watcher.
		1913
		1914	This method synthesizes efficient thunking code to call your method from
		1915	the C callback that libev requires. If your compiler can inline your
		1916	callback (i.e. it is visible to it at the place of the C<set> call and
		1917	your compiler is good :), then the method will be fully inlined into the
		1918	thunking function, making it as fast as a direct C callback.
		1919
		1920	Example: simple class declaration and watcher initialisation
		1921
		1922	struct myclass
		1923	{
		1924	void io_cb (ev::io &w, int revents) { }
		1925	}
		1926
		1927	myclass obj;
		1928	ev::io iow;
		1929	iow.set <myclass, &myclass::io_cb> (&obj);
		1930
		1931	=item w->set<function> (void *data = 0)
		1932
		1933	Also sets a callback, but uses a static method or plain function as
		1934	callback. The optional C<data> argument will be stored in the watcher's
		1935	C<data> member and is free for you to use.
		1936
		1937	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		1938
		1939	See the method-C<set> above for more details.
		1940
		1941	Example:
		1942
		1943	static void io_cb (ev::io &w, int revents) { }
		1944	iow.set <io_cb> ();
1682		1945
1683	=item w->set (struct ev_loop *)	1946	=item w->set (struct ev_loop *)
1684		1947
1685	Associates a different C<struct ev_loop> with this watcher. You can only	1948	Associates a different C<struct ev_loop> with this watcher. You can only
1686	do this when the watcher is inactive (and not pending either).	1949	do this when the watcher is inactive (and not pending either).
1687		1950
1688	=item w->set ([args])	1951	=item w->set ([args])
1689		1952
1690	Basically the same as C<ev_TYPE_set>, with the same args. Must be	1953	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1691	called at least once. Unlike the C counterpart, an active watcher gets	1954	called at least once. Unlike the C counterpart, an active watcher gets
1692	automatically stopped and restarted.	1955	automatically stopped and restarted when reconfiguring it with this
		1956	method.
1693		1957
1694	=item w->start ()	1958	=item w->start ()
1695		1959
1696	Starts the watcher. Note that there is no C<loop> argument as the	1960	Starts the watcher. Note that there is no C<loop> argument, as the
1697	constructor already takes the loop.	1961	constructor already stores the event loop.
1698		1962
1699	=item w->stop ()	1963	=item w->stop ()
1700		1964
1701	Stops the watcher if it is active. Again, no C<loop> argument.	1965	Stops the watcher if it is active. Again, no C<loop> argument.
1702		1966
…		…
1727		1991
1728	myclass ();	1992	myclass ();
1729	}	1993	}
1730		1994
1731	myclass::myclass (int fd)	1995	myclass::myclass (int fd)
1732	: io (this, &myclass::io_cb),
1733	idle (this, &myclass::idle_cb)
1734	{	1996	{
		1997	io .set <myclass, &myclass::io_cb > (this);
		1998	idle.set <myclass, &myclass::idle_cb> (this);
		1999
1735	io.start (fd, ev::READ);	2000	io.start (fd, ev::READ);
1736	}	2001	}
1737		2002
1738		2003
1739	=head1 MACRO MAGIC	2004	=head1 MACRO MAGIC
1740		2005
1741	Libev can be compiled with a variety of options, the most fundemantal is	2006	Libev can be compiled with a variety of options, the most fundemantal is
1742	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2007	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
1743	callbacks have an initial C<struct ev_loop *> argument.	2008	callbacks have an initial C<struct ev_loop *> argument.
1744		2009
1745	To make it easier to write programs that cope with either variant, the	2010	To make it easier to write programs that cope with either variant, the
1746	following macros are defined:	2011	following macros are defined:
1747		2012
…		…
1780	Similar to the other two macros, this gives you the value of the default	2045	Similar to the other two macros, this gives you the value of the default
1781	loop, if multiple loops are supported ("ev loop default").	2046	loop, if multiple loops are supported ("ev loop default").
1782		2047
1783	=back	2048	=back
1784		2049
1785	Example: Declare and initialise a check watcher, working regardless of	2050	Example: Declare and initialise a check watcher, utilising the above
1786	wether multiple loops are supported or not.	2051	macros so it will work regardless of whether multiple loops are supported
		2052	or not.
1787		2053
1788	static void	2054	static void
1789	check_cb (EV_P_ ev_timer *w, int revents)	2055	check_cb (EV_P_ ev_timer *w, int revents)
1790	{	2056	{
1791	ev_check_stop (EV_A_ w);	2057	ev_check_stop (EV_A_ w);
…		…
1793		2059
1794	ev_check check;	2060	ev_check check;
1795	ev_check_init (&check, check_cb);	2061	ev_check_init (&check, check_cb);
1796	ev_check_start (EV_DEFAULT_ &check);	2062	ev_check_start (EV_DEFAULT_ &check);
1797	ev_loop (EV_DEFAULT_ 0);	2063	ev_loop (EV_DEFAULT_ 0);
1798
1799		2064
1800	=head1 EMBEDDING	2065	=head1 EMBEDDING
1801		2066
1802	Libev can (and often is) directly embedded into host	2067	Libev can (and often is) directly embedded into host
1803	applications. Examples of applications that embed it include the Deliantra	2068	applications. Examples of applications that embed it include the Deliantra
…		…
1843	ev_vars.h	2108	ev_vars.h
1844	ev_wrap.h	2109	ev_wrap.h
1845		2110
1846	ev_win32.c required on win32 platforms only	2111	ev_win32.c required on win32 platforms only
1847		2112
1848	ev_select.c only when select backend is enabled (which is by default)	2113	ev_select.c only when select backend is enabled (which is enabled by default)
1849	ev_poll.c only when poll backend is enabled (disabled by default)	2114	ev_poll.c only when poll backend is enabled (disabled by default)
1850	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2115	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1851	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2116	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1852	ev_port.c only when the solaris port backend is enabled (disabled by default)	2117	ev_port.c only when the solaris port backend is enabled (disabled by default)
1853		2118
…		…
1978		2243
1979	=item EV_USE_DEVPOLL	2244	=item EV_USE_DEVPOLL
1980		2245
1981	reserved for future expansion, works like the USE symbols above.	2246	reserved for future expansion, works like the USE symbols above.
1982		2247
		2248	=item EV_USE_INOTIFY
		2249
		2250	If defined to be C<1>, libev will compile in support for the Linux inotify
		2251	interface to speed up C<ev_stat> watchers. Its actual availability will
		2252	be detected at runtime.
		2253
1983	=item EV_H	2254	=item EV_H
1984		2255
1985	The name of the F<ev.h> header file used to include it. The default if	2256	The name of the F<ev.h> header file used to include it. The default if
1986	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2257	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
1987	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2258	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
2010	will have the C<struct ev_loop *> as first argument, and you can create	2281	will have the C<struct ev_loop *> as first argument, and you can create
2011	additional independent event loops. Otherwise there will be no support	2282	additional independent event loops. Otherwise there will be no support
2012	for multiple event loops and there is no first event loop pointer	2283	for multiple event loops and there is no first event loop pointer
2013	argument. Instead, all functions act on the single default loop.	2284	argument. Instead, all functions act on the single default loop.
2014		2285
		2286	=item EV_MINPRI
		2287
		2288	=item EV_MAXPRI
		2289
		2290	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2291	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2292	provide for more priorities by overriding those symbols (usually defined
		2293	to be C<-2> and C<2>, respectively).
		2294
		2295	When doing priority-based operations, libev usually has to linearly search
		2296	all the priorities, so having many of them (hundreds) uses a lot of space
		2297	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2298	fine.
		2299
		2300	If your embedding app does not need any priorities, defining these both to
		2301	C<0> will save some memory and cpu.
		2302
2015	=item EV_PERIODIC_ENABLE	2303	=item EV_PERIODIC_ENABLE
2016		2304
2017	If undefined or defined to be C<1>, then periodic timers are supported. If	2305	If undefined or defined to be C<1>, then periodic timers are supported. If
2018	defined to be C<0>, then they are not. Disabling them saves a few kB of	2306	defined to be C<0>, then they are not. Disabling them saves a few kB of
2019	code.	2307	code.
2020		2308
		2309	=item EV_IDLE_ENABLE
		2310
		2311	If undefined or defined to be C<1>, then idle watchers are supported. If
		2312	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2313	code.
		2314
2021	=item EV_EMBED_ENABLE	2315	=item EV_EMBED_ENABLE
2022		2316
2023	If undefined or defined to be C<1>, then embed watchers are supported. If	2317	If undefined or defined to be C<1>, then embed watchers are supported. If
2024	defined to be C<0>, then they are not.	2318	defined to be C<0>, then they are not.
2025		2319
…		…
2042	=item EV_PID_HASHSIZE	2336	=item EV_PID_HASHSIZE
2043		2337
2044	C<ev_child> watchers use a small hash table to distribute workload by	2338	C<ev_child> watchers use a small hash table to distribute workload by
2045	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	2339	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
2046	than enough. If you need to manage thousands of children you might want to	2340	than enough. If you need to manage thousands of children you might want to
2047	increase this value.	2341	increase this value (I<must> be a power of two).
		2342
		2343	=item EV_INOTIFY_HASHSIZE
		2344
		2345	C<ev_staz> watchers use a small hash table to distribute workload by
		2346	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2347	usually more than enough. If you need to manage thousands of C<ev_stat>
		2348	watchers you might want to increase this value (I<must> be a power of
		2349	two).
2048		2350
2049	=item EV_COMMON	2351	=item EV_COMMON
2050		2352
2051	By default, all watchers have a C<void *data> member. By redefining	2353	By default, all watchers have a C<void *data> member. By redefining
2052	this macro to a something else you can include more and other types of	2354	this macro to a something else you can include more and other types of
…		…
2081	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2383	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2082	will be compiled. It is pretty complex because it provides its own header	2384	will be compiled. It is pretty complex because it provides its own header
2083	file.	2385	file.
2084		2386
2085	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2387	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2086	that everybody includes and which overrides some autoconf choices:	2388	that everybody includes and which overrides some configure choices:
2087		2389
		2390	#define EV_MINIMAL 1
2088	#define EV_USE_POLL 0	2391	#define EV_USE_POLL 0
2089	#define EV_MULTIPLICITY 0	2392	#define EV_MULTIPLICITY 0
2090	#define EV_PERIODICS 0	2393	#define EV_PERIODIC_ENABLE 0
		2394	#define EV_STAT_ENABLE 0
		2395	#define EV_FORK_ENABLE 0
2091	#define EV_CONFIG_H <config.h>	2396	#define EV_CONFIG_H <config.h>
		2397	#define EV_MINPRI 0
		2398	#define EV_MAXPRI 0
2092		2399
2093	#include "ev++.h"	2400	#include "ev++.h"
2094		2401
2095	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2402	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2096		2403
…		…
2102		2409
2103	In this section the complexities of (many of) the algorithms used inside	2410	In this section the complexities of (many of) the algorithms used inside
2104	libev will be explained. For complexity discussions about backends see the	2411	libev will be explained. For complexity discussions about backends see the
2105	documentation for C<ev_default_init>.	2412	documentation for C<ev_default_init>.
2106		2413
		2414	All of the following are about amortised time: If an array needs to be
		2415	extended, libev needs to realloc and move the whole array, but this
		2416	happens asymptotically never with higher number of elements, so O(1) might
		2417	mean it might do a lengthy realloc operation in rare cases, but on average
		2418	it is much faster and asymptotically approaches constant time.
		2419
2107	=over 4	2420	=over 4
2108		2421
2109	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2422	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2110		2423
		2424	This means that, when you have a watcher that triggers in one hour and
		2425	there are 100 watchers that would trigger before that then inserting will
		2426	have to skip those 100 watchers.
		2427
2111	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2428	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2112		2429
		2430	That means that for changing a timer costs less than removing/adding them
		2431	as only the relative motion in the event queue has to be paid for.
		2432
2113	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2433	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2114		2434
		2435	These just add the watcher into an array or at the head of a list.
2115	=item Stopping check/prepare/idle watchers: O(1)	2436	=item Stopping check/prepare/idle watchers: O(1)
2116		2437
2117	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2438	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2439
		2440	These watchers are stored in lists then need to be walked to find the
		2441	correct watcher to remove. The lists are usually short (you don't usually
		2442	have many watchers waiting for the same fd or signal).
2118		2443
2119	=item Finding the next timer per loop iteration: O(1)	2444	=item Finding the next timer per loop iteration: O(1)
2120		2445
2121	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2446	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2122		2447
		2448	A change means an I/O watcher gets started or stopped, which requires
		2449	libev to recalculate its status (and possibly tell the kernel).
		2450
2123	=item Activating one watcher: O(1)	2451	=item Activating one watcher: O(1)
2124		2452
		2453	=item Priority handling: O(number_of_priorities)
		2454
		2455	Priorities are implemented by allocating some space for each
		2456	priority. When doing priority-based operations, libev usually has to
		2457	linearly search all the priorities.
		2458
2125	=back	2459	=back
2126		2460
2127		2461
2128	=head1 AUTHOR	2462	=head1 AUTHOR
2129		2463

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Comparing libev/ev.pod (file contents): Revision 1.53 by root, Tue Nov 27 20:15:02 2007 UTC vs. Revision 1.77 by root, Sat Dec 8 22:11:14 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.53 by root, Tue Nov 27 20:15:02 2007 UTC vs.
Revision 1.77 by root, Sat Dec 8 22:11:14 2007 UTC