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

Comparing libev/ev.pod (file contents):
Revision 1.54 by root, Tue Nov 27 20:26:51 2007 UTC vs.
Revision 1.83 by root, Wed Dec 12 17:55:31 2007 UTC

…		…
47		47
48	return 0;	48	return 0;
49	}	49	}
50		50
51	=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>.
52		56
53	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
54	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
55	these event sources and provide your program with events.	59	these event sources and provide your program with events.
56		60
…		…
63	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
64	watcher.	68	watcher.
65		69
66	=head1 FEATURES	70	=head1 FEATURES
67		71
68	Libev supports C<select>, C<poll>, the linux-specific C<epoll>, the	72	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
69	bsd-specific C<kqueue> and the solaris-specific event port mechanisms	73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
70	for file descriptor events (C<ev_io>), relative timers (C<ev_timer>),	74	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
		75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
71	absolute timers with customised rescheduling (C<ev_periodic>), synchronous	76	with customised rescheduling (C<ev_periodic>), synchronous signals
72	signals (C<ev_signal>), process status change events (C<ev_child>), and	77	(C<ev_signal>), process status change events (C<ev_child>), and event
73	event watchers dealing with the event loop mechanism itself (C<ev_idle>,	78	watchers dealing with the event loop mechanism itself (C<ev_idle>,
74	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as	79	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
75	file watchers (C<ev_stat>) and even limited support for fork events	80	file watchers (C<ev_stat>) and even limited support for fork events
76	(C<ev_fork>).	81	(C<ev_fork>).
77		82
78	It also is quite fast (see this	83	It also is quite fast (see this
…		…
112		117
113	=item int ev_version_major ()	118	=item int ev_version_major ()
114		119
115	=item int ev_version_minor ()	120	=item int ev_version_minor ()
116		121
117	You can find out the major and minor version numbers of the library	122	You can find out the major and minor ABI version numbers of the library
118	you linked against by calling the functions C<ev_version_major> and	123	you linked against by calling the functions C<ev_version_major> and
119	C<ev_version_minor>. If you want, you can compare against the global	124	C<ev_version_minor>. If you want, you can compare against the global
120	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the	125	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
121	version of the library your program was compiled against.	126	version of the library your program was compiled against.
122		127
		128	These version numbers refer to the ABI version of the library, not the
		129	release version.
		130
123	Usually, it's a good idea to terminate if the major versions mismatch,	131	Usually, it's a good idea to terminate if the major versions mismatch,
124	as this indicates an incompatible change. Minor versions are usually	132	as this indicates an incompatible change. Minor versions are usually
125	compatible to older versions, so a larger minor version alone is usually	133	compatible to older versions, so a larger minor version alone is usually
126	not a problem.	134	not a problem.
127		135
128	Example: Make sure we haven't accidentally been linked against the wrong	136	Example: Make sure we haven't accidentally been linked against the wrong
129	version.	137	version.
…		…
162	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	170	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
163	recommended ones.	171	recommended ones.
164		172
165	See the description of C<ev_embed> watchers for more info.	173	See the description of C<ev_embed> watchers for more info.
166		174
167	=item ev_set_allocator (void (cb)(void *ptr, size_t size))	175	=item ev_set_allocator (void (cb)(void *ptr, long size))
168		176
169	Sets the allocation function to use (the prototype and semantics are	177	Sets the allocation function to use (the prototype is similar - the
170	identical to the realloc C function). It is used to allocate and free	178	semantics is identical - to the realloc C function). It is used to
171	memory (no surprises here). If it returns zero when memory needs to be	179	allocate and free memory (no surprises here). If it returns zero when
172	allocated, the library might abort or take some potentially destructive	180	memory needs to be allocated, the library might abort or take some
173	action. The default is your system realloc function.	181	potentially destructive action. The default is your system realloc
		182	function.
174		183
175	You could override this function in high-availability programs to, say,	184	You could override this function in high-availability programs to, say,
176	free some memory if it cannot allocate memory, to use a special allocator,	185	free some memory if it cannot allocate memory, to use a special allocator,
177	or even to sleep a while and retry until some memory is available.	186	or even to sleep a while and retry until some memory is available.
178		187
…		…
264	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	273	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
265	override the flags completely if it is found in the environment. This is	274	override the flags completely if it is found in the environment. This is
266	useful to try out specific backends to test their performance, or to work	275	useful to try out specific backends to test their performance, or to work
267	around bugs.	276	around bugs.
268		277
		278	=item C<EVFLAG_FORKCHECK>
		279
		280	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		281	a fork, you can also make libev check for a fork in each iteration by
		282	enabling this flag.
		283
		284	This works by calling C<getpid ()> on every iteration of the loop,
		285	and thus this might slow down your event loop if you do a lot of loop
		286	iterations and little real work, but is usually not noticeable (on my
		287	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		288	without a syscall and thus I<very> fast, but my Linux system also has
		289	C<pthread_atfork> which is even faster).
		290
		291	The big advantage of this flag is that you can forget about fork (and
		292	forget about forgetting to tell libev about forking) when you use this
		293	flag.
		294
		295	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		296	environment variable.
		297
269	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	298	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
270		299
271	This is your standard select(2) backend. Not I<completely> standard, as	300	This is your standard select(2) backend. Not I<completely> standard, as
272	libev tries to roll its own fd_set with no limits on the number of fds,	301	libev tries to roll its own fd_set with no limits on the number of fds,
273	but if that fails, expect a fairly low limit on the number of fds when	302	but if that fails, expect a fairly low limit on the number of fds when
…		…
408		437
409	Like C<ev_default_fork>, but acts on an event loop created by	438	Like C<ev_default_fork>, but acts on an event loop created by
410	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	439	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
411	after fork, and how you do this is entirely your own problem.	440	after fork, and how you do this is entirely your own problem.
412		441
		442	=item unsigned int ev_loop_count (loop)
		443
		444	Returns the count of loop iterations for the loop, which is identical to
		445	the number of times libev did poll for new events. It starts at C<0> and
		446	happily wraps around with enough iterations.
		447
		448	This value can sometimes be useful as a generation counter of sorts (it
		449	"ticks" the number of loop iterations), as it roughly corresponds with
		450	C<ev_prepare> and C<ev_check> calls.
		451
413	=item unsigned int ev_backend (loop)	452	=item unsigned int ev_backend (loop)
414		453
415	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	454	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
416	use.	455	use.
417		456
…		…
450	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	489	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
451	usually a better approach for this kind of thing.	490	usually a better approach for this kind of thing.
452		491
453	Here are the gory details of what C<ev_loop> does:	492	Here are the gory details of what C<ev_loop> does:
454		493
		494	- Before the first iteration, call any pending watchers.
455	* If there are no active watchers (reference count is zero), return.	495	* If there are no active watchers (reference count is zero), return.
456	- Queue prepare watchers and then call all outstanding watchers.	496	- Queue all prepare watchers and then call all outstanding watchers.
457	- If we have been forked, recreate the kernel state.	497	- If we have been forked, recreate the kernel state.
458	- Update the kernel state with all outstanding changes.	498	- Update the kernel state with all outstanding changes.
459	- Update the "event loop time".	499	- Update the "event loop time".
460	- Calculate for how long to block.	500	- Calculate for how long to block.
461	- Block the process, waiting for any events.	501	- Block the process, waiting for any events.
…		…
700	=item bool ev_is_pending (ev_TYPE *watcher)	740	=item bool ev_is_pending (ev_TYPE *watcher)
701		741
702	Returns a true value iff the watcher is pending, (i.e. it has outstanding	742	Returns a true value iff the watcher is pending, (i.e. it has outstanding
703	events but its callback has not yet been invoked). As long as a watcher	743	events but its callback has not yet been invoked). As long as a watcher
704	is pending (but not active) you must not call an init function on it (but	744	is pending (but not active) you must not call an init function on it (but
705	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	745	C<ev_TYPE_set> is safe), you must not change its priority, and you must
706	libev (e.g. you cnanot C<free ()> it).	746	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		747	it).
707		748
708	=item callback = ev_cb (ev_TYPE *watcher)	749	=item callback ev_cb (ev_TYPE *watcher)
709		750
710	Returns the callback currently set on the watcher.	751	Returns the callback currently set on the watcher.
711		752
712	=item ev_cb_set (ev_TYPE *watcher, callback)	753	=item ev_cb_set (ev_TYPE *watcher, callback)
713		754
714	Change the callback. You can change the callback at virtually any time	755	Change the callback. You can change the callback at virtually any time
715	(modulo threads).	756	(modulo threads).
		757
		758	=item ev_set_priority (ev_TYPE *watcher, priority)
		759
		760	=item int ev_priority (ev_TYPE *watcher)
		761
		762	Set and query the priority of the watcher. The priority is a small
		763	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		764	(default: C<-2>). Pending watchers with higher priority will be invoked
		765	before watchers with lower priority, but priority will not keep watchers
		766	from being executed (except for C<ev_idle> watchers).
		767
		768	This means that priorities are I<only> used for ordering callback
		769	invocation after new events have been received. This is useful, for
		770	example, to reduce latency after idling, or more often, to bind two
		771	watchers on the same event and make sure one is called first.
		772
		773	If you need to suppress invocation when higher priority events are pending
		774	you need to look at C<ev_idle> watchers, which provide this functionality.
		775
		776	You I<must not> change the priority of a watcher as long as it is active or
		777	pending.
		778
		779	The default priority used by watchers when no priority has been set is
		780	always C<0>, which is supposed to not be too high and not be too low :).
		781
		782	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		783	fine, as long as you do not mind that the priority value you query might
		784	or might not have been adjusted to be within valid range.
		785
		786	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		787
		788	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		789	C<loop> nor C<revents> need to be valid as long as the watcher callback
		790	can deal with that fact.
		791
		792	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		793
		794	If the watcher is pending, this function returns clears its pending status
		795	and returns its C<revents> bitset (as if its callback was invoked). If the
		796	watcher isn't pending it does nothing and returns C<0>.
716		797
717	=back	798	=back
718		799
719		800
720	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	801	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
741	{	822	{
742	struct my_io w = (struct my_io )w_;	823	struct my_io w = (struct my_io )w_;
743	...	824	...
744	}	825	}
745		826
746	More interesting and less C-conformant ways of catsing your callback type	827	More interesting and less C-conformant ways of casting your callback type
747	have been omitted....	828	instead have been omitted.
		829
		830	Another common scenario is having some data structure with multiple
		831	watchers:
		832
		833	struct my_biggy
		834	{
		835	int some_data;
		836	ev_timer t1;
		837	ev_timer t2;
		838	}
		839
		840	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		841	you need to use C<offsetof>:
		842
		843	#include <stddef.h>
		844
		845	static void
		846	t1_cb (EV_P_ struct ev_timer *w, int revents)
		847	{
		848	struct my_biggy big = (struct my_biggy *
		849	(((char *)w) - offsetof (struct my_biggy, t1));
		850	}
		851
		852	static void
		853	t2_cb (EV_P_ struct ev_timer *w, int revents)
		854	{
		855	struct my_biggy big = (struct my_biggy *
		856	(((char *)w) - offsetof (struct my_biggy, t2));
		857	}
748		858
749		859
750	=head1 WATCHER TYPES	860	=head1 WATCHER TYPES
751		861
752	This section describes each watcher in detail, but will not repeat	862	This section describes each watcher in detail, but will not repeat
…		…
797	it is best to always use non-blocking I/O: An extra C<read>(2) returning	907	it is best to always use non-blocking I/O: An extra C<read>(2) returning
798	C<EAGAIN> is far preferable to a program hanging until some data arrives.	908	C<EAGAIN> is far preferable to a program hanging until some data arrives.
799		909
800	If you cannot run the fd in non-blocking mode (for example you should not	910	If you cannot run the fd in non-blocking mode (for example you should not
801	play around with an Xlib connection), then you have to seperately re-test	911	play around with an Xlib connection), then you have to seperately re-test
802	wether a file descriptor is really ready with a known-to-be good interface	912	whether a file descriptor is really ready with a known-to-be good interface
803	such as poll (fortunately in our Xlib example, Xlib already does this on	913	such as poll (fortunately in our Xlib example, Xlib already does this on
804	its own, so its quite safe to use).	914	its own, so its quite safe to use).
		915
		916	=head3 The special problem of disappearing file descriptors
		917
		918	Some backends (e.g kqueue, epoll) need to be told about closing a file
		919	descriptor (either by calling C<close> explicitly or by any other means,
		920	such as C<dup>). The reason is that you register interest in some file
		921	descriptor, but when it goes away, the operating system will silently drop
		922	this interest. If another file descriptor with the same number then is
		923	registered with libev, there is no efficient way to see that this is, in
		924	fact, a different file descriptor.
		925
		926	To avoid having to explicitly tell libev about such cases, libev follows
		927	the following policy: Each time C<ev_io_set> is being called, libev
		928	will assume that this is potentially a new file descriptor, otherwise
		929	it is assumed that the file descriptor stays the same. That means that
		930	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		931	descriptor even if the file descriptor number itself did not change.
		932
		933	This is how one would do it normally anyway, the important point is that
		934	the libev application should not optimise around libev but should leave
		935	optimisations to libev.
		936
		937
		938	=head3 Watcher-Specific Functions
805		939
806	=over 4	940	=over 4
807		941
808	=item ev_io_init (ev_io *, callback, int fd, int events)	942	=item ev_io_init (ev_io *, callback, int fd, int events)
809		943
…		…
863		997
864	The callback is guarenteed to be invoked only when its timeout has passed,	998	The callback is guarenteed to be invoked only when its timeout has passed,
865	but if multiple timers become ready during the same loop iteration then	999	but if multiple timers become ready during the same loop iteration then
866	order of execution is undefined.	1000	order of execution is undefined.
867		1001
		1002	=head3 Watcher-Specific Functions and Data Members
		1003
868	=over 4	1004	=over 4
869		1005
870	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1006	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
871		1007
872	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1008	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
885	=item ev_timer_again (loop)	1021	=item ev_timer_again (loop)
886		1022
887	This will act as if the timer timed out and restart it again if it is	1023	This will act as if the timer timed out and restart it again if it is
888	repeating. The exact semantics are:	1024	repeating. The exact semantics are:
889		1025
		1026	If the timer is pending, its pending status is cleared.
		1027
890	If the timer is started but nonrepeating, stop it.	1028	If the timer is started but nonrepeating, stop it (as if it timed out).
891		1029
892	If the timer is repeating, either start it if necessary (with the repeat	1030	If the timer is repeating, either start it if necessary (with the
893	value), or reset the running timer to the repeat value.	1031	C<repeat> value), or reset the running timer to the C<repeat> value.
894		1032
895	This sounds a bit complicated, but here is a useful and typical	1033	This sounds a bit complicated, but here is a useful and typical
896	example: Imagine you have a tcp connection and you want a so-called	1034	example: Imagine you have a tcp connection and you want a so-called idle
897	idle timeout, that is, you want to be called when there have been,	1035	timeout, that is, you want to be called when there have been, say, 60
898	say, 60 seconds of inactivity on the socket. The easiest way to do	1036	seconds of inactivity on the socket. The easiest way to do this is to
899	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling	1037	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
900	C<ev_timer_again> each time you successfully read or write some data. If	1038	C<ev_timer_again> each time you successfully read or write some data. If
901	you go into an idle state where you do not expect data to travel on the	1039	you go into an idle state where you do not expect data to travel on the
902	socket, you can stop the timer, and again will automatically restart it if	1040	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
903	need be.	1041	automatically restart it if need be.
904		1042
905	You can also ignore the C<after> value and C<ev_timer_start> altogether	1043	That means you can ignore the C<after> value and C<ev_timer_start>
906	and only ever use the C<repeat> value:	1044	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
907		1045
908	ev_timer_init (timer, callback, 0., 5.);	1046	ev_timer_init (timer, callback, 0., 5.);
909	ev_timer_again (loop, timer);	1047	ev_timer_again (loop, timer);
910	...	1048	...
911	timer->again = 17.;	1049	timer->again = 17.;
912	ev_timer_again (loop, timer);	1050	ev_timer_again (loop, timer);
913	...	1051	...
914	timer->again = 10.;	1052	timer->again = 10.;
915	ev_timer_again (loop, timer);	1053	ev_timer_again (loop, timer);
916		1054
917	This is more efficient then stopping/starting the timer eahc time you want	1055	This is more slightly efficient then stopping/starting the timer each time
918	to modify its timeout value.	1056	you want to modify its timeout value.
919		1057
920	=item ev_tstamp repeat [read-write]	1058	=item ev_tstamp repeat [read-write]
921		1059
922	The current C<repeat> value. Will be used each time the watcher times out	1060	The current C<repeat> value. Will be used each time the watcher times out
923	or C<ev_timer_again> is called and determines the next timeout (if any),	1061	or C<ev_timer_again> is called and determines the next timeout (if any),
…		…
965	but on wallclock time (absolute time). You can tell a periodic watcher	1103	but on wallclock time (absolute time). You can tell a periodic watcher
966	to trigger "at" some specific point in time. For example, if you tell a	1104	to trigger "at" some specific point in time. For example, if you tell a
967	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1105	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
968	+ 10.>) and then reset your system clock to the last year, then it will	1106	+ 10.>) and then reset your system clock to the last year, then it will
969	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1107	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
970	roughly 10 seconds later and of course not if you reset your system time	1108	roughly 10 seconds later).
971	again).
972		1109
973	They can also be used to implement vastly more complex timers, such as	1110	They can also be used to implement vastly more complex timers, such as
974	triggering an event on eahc midnight, local time.	1111	triggering an event on each midnight, local time or other, complicated,
		1112	rules.
975		1113
976	As with timers, the callback is guarenteed to be invoked only when the	1114	As with timers, the callback is guarenteed to be invoked only when the
977	time (C<at>) has been passed, but if multiple periodic timers become ready	1115	time (C<at>) has been passed, but if multiple periodic timers become ready
978	during the same loop iteration then order of execution is undefined.	1116	during the same loop iteration then order of execution is undefined.
979		1117
		1118	=head3 Watcher-Specific Functions and Data Members
		1119
980	=over 4	1120	=over 4
981		1121
982	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1122	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
983		1123
984	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1124	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
986	Lots of arguments, lets sort it out... There are basically three modes of	1126	Lots of arguments, lets sort it out... There are basically three modes of
987	operation, and we will explain them from simplest to complex:	1127	operation, and we will explain them from simplest to complex:
988		1128
989	=over 4	1129	=over 4
990		1130
991	=item * absolute timer (interval = reschedule_cb = 0)	1131	=item * absolute timer (at = time, interval = reschedule_cb = 0)
992		1132
993	In this configuration the watcher triggers an event at the wallclock time	1133	In this configuration the watcher triggers an event at the wallclock time
994	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1134	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
995	that is, if it is to be run at January 1st 2011 then it will run when the	1135	that is, if it is to be run at January 1st 2011 then it will run when the
996	system time reaches or surpasses this time.	1136	system time reaches or surpasses this time.
997		1137
998	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1138	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
999		1139
1000	In this mode the watcher will always be scheduled to time out at the next	1140	In this mode the watcher will always be scheduled to time out at the next
1001	C<at + N * interval> time (for some integer N) and then repeat, regardless	1141	C<at + N * interval> time (for some integer N, which can also be negative)
1002	of any time jumps.	1142	and then repeat, regardless of any time jumps.
1003		1143
1004	This can be used to create timers that do not drift with respect to system	1144	This can be used to create timers that do not drift with respect to system
1005	time:	1145	time:
1006		1146
1007	ev_periodic_set (&periodic, 0., 3600., 0);	1147	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1013		1153
1014	Another way to think about it (for the mathematically inclined) is that	1154	Another way to think about it (for the mathematically inclined) is that
1015	C<ev_periodic> will try to run the callback in this mode at the next possible	1155	C<ev_periodic> will try to run the callback in this mode at the next possible
1016	time where C<time = at (mod interval)>, regardless of any time jumps.	1156	time where C<time = at (mod interval)>, regardless of any time jumps.
1017		1157
		1158	For numerical stability it is preferable that the C<at> value is near
		1159	C<ev_now ()> (the current time), but there is no range requirement for
		1160	this value.
		1161
1018	=item * manual reschedule mode (reschedule_cb = callback)	1162	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1019		1163
1020	In this mode the values for C<interval> and C<at> are both being	1164	In this mode the values for C<interval> and C<at> are both being
1021	ignored. Instead, each time the periodic watcher gets scheduled, the	1165	ignored. Instead, each time the periodic watcher gets scheduled, the
1022	reschedule callback will be called with the watcher as first, and the	1166	reschedule callback will be called with the watcher as first, and the
1023	current time as second argument.	1167	current time as second argument.
1024		1168
1025	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1169	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1026	ever, or make any event loop modifications>. If you need to stop it,	1170	ever, or make any event loop modifications>. If you need to stop it,
1027	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1171	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1028	starting a prepare watcher).	1172	starting an C<ev_prepare> watcher, which is legal).
1029		1173
1030	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	1174	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
1031	ev_tstamp now)>, e.g.:	1175	ev_tstamp now)>, e.g.:
1032		1176
1033	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1177	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
1055		1199
1056	Simply stops and restarts the periodic watcher again. This is only useful	1200	Simply stops and restarts the periodic watcher again. This is only useful
1057	when you changed some parameters or the reschedule callback would return	1201	when you changed some parameters or the reschedule callback would return
1058	a different time than the last time it was called (e.g. in a crond like	1202	a different time than the last time it was called (e.g. in a crond like
1059	program when the crontabs have changed).	1203	program when the crontabs have changed).
		1204
		1205	=item ev_tstamp offset [read-write]
		1206
		1207	When repeating, this contains the offset value, otherwise this is the
		1208	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1209
		1210	Can be modified any time, but changes only take effect when the periodic
		1211	timer fires or C<ev_periodic_again> is being called.
1060		1212
1061	=item ev_tstamp interval [read-write]	1213	=item ev_tstamp interval [read-write]
1062		1214
1063	The current interval value. Can be modified any time, but changes only	1215	The current interval value. Can be modified any time, but changes only
1064	take effect when the periodic timer fires or C<ev_periodic_again> is being	1216	take effect when the periodic timer fires or C<ev_periodic_again> is being
…		…
1118	with the kernel (thus it coexists with your own signal handlers as long	1270	with the kernel (thus it coexists with your own signal handlers as long
1119	as you don't register any with libev). Similarly, when the last signal	1271	as you don't register any with libev). Similarly, when the last signal
1120	watcher for a signal is stopped libev will reset the signal handler to	1272	watcher for a signal is stopped libev will reset the signal handler to
1121	SIG_DFL (regardless of what it was set to before).	1273	SIG_DFL (regardless of what it was set to before).
1122		1274
		1275	=head3 Watcher-Specific Functions and Data Members
		1276
1123	=over 4	1277	=over 4
1124		1278
1125	=item ev_signal_init (ev_signal *, callback, int signum)	1279	=item ev_signal_init (ev_signal *, callback, int signum)
1126		1280
1127	=item ev_signal_set (ev_signal *, int signum)	1281	=item ev_signal_set (ev_signal *, int signum)
…		…
1138		1292
1139	=head2 C<ev_child> - watch out for process status changes	1293	=head2 C<ev_child> - watch out for process status changes
1140		1294
1141	Child watchers trigger when your process receives a SIGCHLD in response to	1295	Child watchers trigger when your process receives a SIGCHLD in response to
1142	some child status changes (most typically when a child of yours dies).	1296	some child status changes (most typically when a child of yours dies).
		1297
		1298	=head3 Watcher-Specific Functions and Data Members
1143		1299
1144	=over 4	1300	=over 4
1145		1301
1146	=item ev_child_init (ev_child *, callback, int pid)	1302	=item ev_child_init (ev_child *, callback, int pid)
1147		1303
…		…
1192	not exist" is a status change like any other. The condition "path does	1348	not exist" is a status change like any other. The condition "path does
1193	not exist" is signified by the C<st_nlink> field being zero (which is	1349	not exist" is signified by the C<st_nlink> field being zero (which is
1194	otherwise always forced to be at least one) and all the other fields of	1350	otherwise always forced to be at least one) and all the other fields of
1195	the stat buffer having unspecified contents.	1351	the stat buffer having unspecified contents.
1196		1352
		1353	The path I<should> be absolute and I<must not> end in a slash. If it is
		1354	relative and your working directory changes, the behaviour is undefined.
		1355
1197	Since there is no standard to do this, the portable implementation simply	1356	Since there is no standard to do this, the portable implementation simply
1198	calls C<stat (2)> regulalry on the path to see if it changed somehow. You	1357	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1199	can specify a recommended polling interval for this case. If you specify	1358	can specify a recommended polling interval for this case. If you specify
1200	a polling interval of C<0> (highly recommended!) then a I<suitable,	1359	a polling interval of C<0> (highly recommended!) then a I<suitable,
1201	unspecified default> value will be used (which you can expect to be around	1360	unspecified default> value will be used (which you can expect to be around
1202	five seconds, although this might change dynamically). Libev will also	1361	five seconds, although this might change dynamically). Libev will also
1203	impose a minimum interval which is currently around C<0.1>, but thats	1362	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1205		1364
1206	This watcher type is not meant for massive numbers of stat watchers,	1365	This watcher type is not meant for massive numbers of stat watchers,
1207	as even with OS-supported change notifications, this can be	1366	as even with OS-supported change notifications, this can be
1208	resource-intensive.	1367	resource-intensive.
1209		1368
1210	At the time of this writing, no specific OS backends are implemented, but	1369	At the time of this writing, only the Linux inotify interface is
1211	if demand increases, at least a kqueue and inotify backend will be added.	1370	implemented (implementing kqueue support is left as an exercise for the
		1371	reader). Inotify will be used to give hints only and should not change the
		1372	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1373	to fall back to regular polling again even with inotify, but changes are
		1374	usually detected immediately, and if the file exists there will be no
		1375	polling.
		1376
		1377	=head3 Watcher-Specific Functions and Data Members
1212		1378
1213	=over 4	1379	=over 4
1214		1380
1215	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1381	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1216		1382
…		…
1280	ev_stat_start (loop, &passwd);	1446	ev_stat_start (loop, &passwd);
1281		1447
1282		1448
1283	=head2 C<ev_idle> - when you've got nothing better to do...	1449	=head2 C<ev_idle> - when you've got nothing better to do...
1284		1450
1285	Idle watchers trigger events when there are no other events are pending	1451	Idle watchers trigger events when no other events of the same or higher
1286	(prepare, check and other idle watchers do not count). That is, as long	1452	priority are pending (prepare, check and other idle watchers do not
1287	as your process is busy handling sockets or timeouts (or even signals,	1453	count).
1288	imagine) it will not be triggered. But when your process is idle all idle	1454
1289	watchers are being called again and again, once per event loop iteration -	1455	That is, as long as your process is busy handling sockets or timeouts
		1456	(or even signals, imagine) of the same or higher priority it will not be
		1457	triggered. But when your process is idle (or only lower-priority watchers
		1458	are pending), the idle watchers are being called once per event loop
1290	until stopped, that is, or your process receives more events and becomes	1459	iteration - until stopped, that is, or your process receives more events
1291	busy.	1460	and becomes busy again with higher priority stuff.
1292		1461
1293	The most noteworthy effect is that as long as any idle watchers are	1462	The most noteworthy effect is that as long as any idle watchers are
1294	active, the process will not block when waiting for new events.	1463	active, the process will not block when waiting for new events.
1295		1464
1296	Apart from keeping your process non-blocking (which is a useful	1465	Apart from keeping your process non-blocking (which is a useful
1297	effect on its own sometimes), idle watchers are a good place to do	1466	effect on its own sometimes), idle watchers are a good place to do
1298	"pseudo-background processing", or delay processing stuff to after the	1467	"pseudo-background processing", or delay processing stuff to after the
1299	event loop has handled all outstanding events.	1468	event loop has handled all outstanding events.
		1469
		1470	=head3 Watcher-Specific Functions and Data Members
1300		1471
1301	=over 4	1472	=over 4
1302		1473
1303	=item ev_idle_init (ev_signal *, callback)	1474	=item ev_idle_init (ev_signal *, callback)
1304		1475
…		…
1362	with priority higher than or equal to the event loop and one coroutine	1533	with priority higher than or equal to the event loop and one coroutine
1363	of lower priority, but only once, using idle watchers to keep the event	1534	of lower priority, but only once, using idle watchers to keep the event
1364	loop from blocking if lower-priority coroutines are active, thus mapping	1535	loop from blocking if lower-priority coroutines are active, thus mapping
1365	low-priority coroutines to idle/background tasks).	1536	low-priority coroutines to idle/background tasks).
1366		1537
		1538	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1539	priority, to ensure that they are being run before any other watchers
		1540	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1541	too) should not activate ("feed") events into libev. While libev fully
		1542	supports this, they will be called before other C<ev_check> watchers did
		1543	their job. As C<ev_check> watchers are often used to embed other event
		1544	loops those other event loops might be in an unusable state until their
		1545	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1546	others).
		1547
		1548	=head3 Watcher-Specific Functions and Data Members
		1549
1367	=over 4	1550	=over 4
1368		1551
1369	=item ev_prepare_init (ev_prepare *, callback)	1552	=item ev_prepare_init (ev_prepare *, callback)
1370		1553
1371	=item ev_check_init (ev_check *, callback)	1554	=item ev_check_init (ev_check *, callback)
…		…
1374	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1557	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1375	macros, but using them is utterly, utterly and completely pointless.	1558	macros, but using them is utterly, utterly and completely pointless.
1376		1559
1377	=back	1560	=back
1378		1561
1379	Example: To include a library such as adns, you would add IO watchers	1562	There are a number of principal ways to embed other event loops or modules
1380	and a timeout watcher in a prepare handler, as required by libadns, and	1563	into libev. Here are some ideas on how to include libadns into libev
		1564	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1565	use for an actually working example. Another Perl module named C<EV::Glib>
		1566	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1567	into the Glib event loop).
		1568
		1569	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1381	in a check watcher, destroy them and call into libadns. What follows is	1570	and in a check watcher, destroy them and call into libadns. What follows
1382	pseudo-code only of course:	1571	is pseudo-code only of course. This requires you to either use a low
		1572	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1573	the callbacks for the IO/timeout watchers might not have been called yet.
1383		1574
1384	static ev_io iow [nfd];	1575	static ev_io iow [nfd];
1385	static ev_timer tw;	1576	static ev_timer tw;
1386		1577
1387	static void	1578	static void
1388	io_cb (ev_loop loop, ev_io w, int revents)	1579	io_cb (ev_loop loop, ev_io w, int revents)
1389	{	1580	{
1390	// set the relevant poll flags
1391	// could also call adns_processreadable etc. here
1392	struct pollfd fd = (struct pollfd )w->data;
1393	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1394	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1395	}	1581	}
1396		1582
1397	// create io watchers for each fd and a timer before blocking	1583	// create io watchers for each fd and a timer before blocking
1398	static void	1584	static void
1399	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1585	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1400	{	1586	{
1401	int timeout = 3600000;truct pollfd fds [nfd];	1587	int timeout = 3600000;
		1588	struct pollfd fds [nfd];
1402	// actual code will need to loop here and realloc etc.	1589	// actual code will need to loop here and realloc etc.
1403	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1590	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1404		1591
1405	/* the callback is illegal, but won't be called as we stop during check */	1592	/* the callback is illegal, but won't be called as we stop during check */
1406	ev_timer_init (&tw, 0, timeout * 1e-3);	1593	ev_timer_init (&tw, 0, timeout * 1e-3);
1407	ev_timer_start (loop, &tw);	1594	ev_timer_start (loop, &tw);
1408		1595
1409	// create on ev_io per pollfd	1596	// create one ev_io per pollfd
1410	for (int i = 0; i < nfd; ++i)	1597	for (int i = 0; i < nfd; ++i)
1411	{	1598	{
1412	ev_io_init (iow + i, io_cb, fds [i].fd,	1599	ev_io_init (iow + i, io_cb, fds [i].fd,
1413	((fds [i].events & POLLIN ? EV_READ : 0)	1600	((fds [i].events & POLLIN ? EV_READ : 0)
1414	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1601	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1415		1602
1416	fds [i].revents = 0;	1603	fds [i].revents = 0;
1417	iow [i].data = fds + i;
1418	ev_io_start (loop, iow + i);	1604	ev_io_start (loop, iow + i);
1419	}	1605	}
1420	}	1606	}
1421		1607
1422	// stop all watchers after blocking	1608	// stop all watchers after blocking
…		…
1424	adns_check_cb (ev_loop loop, ev_check w, int revents)	1610	adns_check_cb (ev_loop loop, ev_check w, int revents)
1425	{	1611	{
1426	ev_timer_stop (loop, &tw);	1612	ev_timer_stop (loop, &tw);
1427		1613
1428	for (int i = 0; i < nfd; ++i)	1614	for (int i = 0; i < nfd; ++i)
		1615	{
		1616	// set the relevant poll flags
		1617	// could also call adns_processreadable etc. here
		1618	struct pollfd *fd = fds + i;
		1619	int revents = ev_clear_pending (iow + i);
		1620	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1621	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1622
		1623	// now stop the watcher
1429	ev_io_stop (loop, iow + i);	1624	ev_io_stop (loop, iow + i);
		1625	}
1430		1626
1431	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1627	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1628	}
		1629
		1630	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1631	in the prepare watcher and would dispose of the check watcher.
		1632
		1633	Method 3: If the module to be embedded supports explicit event
		1634	notification (adns does), you can also make use of the actual watcher
		1635	callbacks, and only destroy/create the watchers in the prepare watcher.
		1636
		1637	static void
		1638	timer_cb (EV_P_ ev_timer *w, int revents)
		1639	{
		1640	adns_state ads = (adns_state)w->data;
		1641	update_now (EV_A);
		1642
		1643	adns_processtimeouts (ads, &tv_now);
		1644	}
		1645
		1646	static void
		1647	io_cb (EV_P_ ev_io *w, int revents)
		1648	{
		1649	adns_state ads = (adns_state)w->data;
		1650	update_now (EV_A);
		1651
		1652	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1653	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1654	}
		1655
		1656	// do not ever call adns_afterpoll
		1657
		1658	Method 4: Do not use a prepare or check watcher because the module you
		1659	want to embed is too inflexible to support it. Instead, youc na override
		1660	their poll function. The drawback with this solution is that the main
		1661	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1662	this.
		1663
		1664	static gint
		1665	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1666	{
		1667	int got_events = 0;
		1668
		1669	for (n = 0; n < nfds; ++n)
		1670	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1671
		1672	if (timeout >= 0)
		1673	// create/start timer
		1674
		1675	// poll
		1676	ev_loop (EV_A_ 0);
		1677
		1678	// stop timer again
		1679	if (timeout >= 0)
		1680	ev_timer_stop (EV_A_ &to);
		1681
		1682	// stop io watchers again - their callbacks should have set
		1683	for (n = 0; n < nfds; ++n)
		1684	ev_io_stop (EV_A_ iow [n]);
		1685
		1686	return got_events;
1432	}	1687	}
1433		1688
1434		1689
1435	=head2 C<ev_embed> - when one backend isn't enough...	1690	=head2 C<ev_embed> - when one backend isn't enough...
1436		1691
…		…
1500	ev_embed_start (loop_hi, &embed);	1755	ev_embed_start (loop_hi, &embed);
1501	}	1756	}
1502	else	1757	else
1503	loop_lo = loop_hi;	1758	loop_lo = loop_hi;
1504		1759
		1760	=head3 Watcher-Specific Functions and Data Members
		1761
1505	=over 4	1762	=over 4
1506		1763
1507	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)	1764	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)
1508		1765
1509	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)	1766	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)
…		…
1535	event loop blocks next and before C<ev_check> watchers are being called,	1792	event loop blocks next and before C<ev_check> watchers are being called,
1536	and only in the child after the fork. If whoever good citizen calling	1793	and only in the child after the fork. If whoever good citizen calling
1537	C<ev_default_fork> cheats and calls it in the wrong process, the fork	1794	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1538	handlers will be invoked, too, of course.	1795	handlers will be invoked, too, of course.
1539		1796
		1797	=head3 Watcher-Specific Functions and Data Members
		1798
1540	=over 4	1799	=over 4
1541		1800
1542	=item ev_fork_init (ev_signal *, callback)	1801	=item ev_fork_init (ev_signal *, callback)
1543		1802
1544	Initialises and configures the fork watcher - it has no parameters of any	1803	Initialises and configures the fork watcher - it has no parameters of any
…		…
1640		1899
1641	To use it,	1900	To use it,
1642		1901
1643	#include <ev++.h>	1902	#include <ev++.h>
1644		1903
1645	(it is not installed by default). This automatically includes F<ev.h>	1904	This automatically includes F<ev.h> and puts all of its definitions (many
1646	and puts all of its definitions (many of them macros) into the global	1905	of them macros) into the global namespace. All C++ specific things are
1647	namespace. All C++ specific things are put into the C<ev> namespace.	1906	put into the C<ev> namespace. It should support all the same embedding
		1907	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1648		1908
1649	It should support all the same embedding options as F<ev.h>, most notably	1909	Care has been taken to keep the overhead low. The only data member the C++
1650	C<EV_MULTIPLICITY>.	1910	classes add (compared to plain C-style watchers) is the event loop pointer
		1911	that the watcher is associated with (or no additional members at all if
		1912	you disable C<EV_MULTIPLICITY> when embedding libev).
		1913
		1914	Currently, functions, and static and non-static member functions can be
		1915	used as callbacks. Other types should be easy to add as long as they only
		1916	need one additional pointer for context. If you need support for other
		1917	types of functors please contact the author (preferably after implementing
		1918	it).
1651		1919
1652	Here is a list of things available in the C<ev> namespace:	1920	Here is a list of things available in the C<ev> namespace:
1653		1921
1654	=over 4	1922	=over 4
1655		1923
…		…
1671		1939
1672	All of those classes have these methods:	1940	All of those classes have these methods:
1673		1941
1674	=over 4	1942	=over 4
1675		1943
1676	=item ev::TYPE::TYPE (object , object::method )	1944	=item ev::TYPE::TYPE ()
1677		1945
1678	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1946	=item ev::TYPE::TYPE (struct ev_loop *)
1679		1947
1680	=item ev::TYPE::~TYPE	1948	=item ev::TYPE::~TYPE
1681		1949
1682	The constructor takes a pointer to an object and a method pointer to	1950	The constructor (optionally) takes an event loop to associate the watcher
1683	the event handler callback to call in this class. The constructor calls	1951	with. If it is omitted, it will use C<EV_DEFAULT>.
1684	C<ev_init> for you, which means you have to call the C<set> method	1952
1685	before starting it. If you do not specify a loop then the constructor	1953	The constructor calls C<ev_init> for you, which means you have to call the
1686	automatically associates the default loop with this watcher.	1954	C<set> method before starting it.
		1955
		1956	It will not set a callback, however: You have to call the templated C<set>
		1957	method to set a callback before you can start the watcher.
		1958
		1959	(The reason why you have to use a method is a limitation in C++ which does
		1960	not allow explicit template arguments for constructors).
1687		1961
1688	The destructor automatically stops the watcher if it is active.	1962	The destructor automatically stops the watcher if it is active.
		1963
		1964	=item w->set<class, &class::method> (object *)
		1965
		1966	This method sets the callback method to call. The method has to have a
		1967	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1968	first argument and the C<revents> as second. The object must be given as
		1969	parameter and is stored in the C<data> member of the watcher.
		1970
		1971	This method synthesizes efficient thunking code to call your method from
		1972	the C callback that libev requires. If your compiler can inline your
		1973	callback (i.e. it is visible to it at the place of the C<set> call and
		1974	your compiler is good :), then the method will be fully inlined into the
		1975	thunking function, making it as fast as a direct C callback.
		1976
		1977	Example: simple class declaration and watcher initialisation
		1978
		1979	struct myclass
		1980	{
		1981	void io_cb (ev::io &w, int revents) { }
		1982	}
		1983
		1984	myclass obj;
		1985	ev::io iow;
		1986	iow.set <myclass, &myclass::io_cb> (&obj);
		1987
		1988	=item w->set<function> (void *data = 0)
		1989
		1990	Also sets a callback, but uses a static method or plain function as
		1991	callback. The optional C<data> argument will be stored in the watcher's
		1992	C<data> member and is free for you to use.
		1993
		1994	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		1995
		1996	See the method-C<set> above for more details.
		1997
		1998	Example:
		1999
		2000	static void io_cb (ev::io &w, int revents) { }
		2001	iow.set <io_cb> ();
1689		2002
1690	=item w->set (struct ev_loop *)	2003	=item w->set (struct ev_loop *)
1691		2004
1692	Associates a different C<struct ev_loop> with this watcher. You can only	2005	Associates a different C<struct ev_loop> with this watcher. You can only
1693	do this when the watcher is inactive (and not pending either).	2006	do this when the watcher is inactive (and not pending either).
1694		2007
1695	=item w->set ([args])	2008	=item w->set ([args])
1696		2009
1697	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2010	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1698	called at least once. Unlike the C counterpart, an active watcher gets	2011	called at least once. Unlike the C counterpart, an active watcher gets
1699	automatically stopped and restarted.	2012	automatically stopped and restarted when reconfiguring it with this
		2013	method.
1700		2014
1701	=item w->start ()	2015	=item w->start ()
1702		2016
1703	Starts the watcher. Note that there is no C<loop> argument as the	2017	Starts the watcher. Note that there is no C<loop> argument, as the
1704	constructor already takes the loop.	2018	constructor already stores the event loop.
1705		2019
1706	=item w->stop ()	2020	=item w->stop ()
1707		2021
1708	Stops the watcher if it is active. Again, no C<loop> argument.	2022	Stops the watcher if it is active. Again, no C<loop> argument.
1709		2023
…		…
1734		2048
1735	myclass ();	2049	myclass ();
1736	}	2050	}
1737		2051
1738	myclass::myclass (int fd)	2052	myclass::myclass (int fd)
1739	: io (this, &myclass::io_cb),
1740	idle (this, &myclass::idle_cb)
1741	{	2053	{
		2054	io .set <myclass, &myclass::io_cb > (this);
		2055	idle.set <myclass, &myclass::idle_cb> (this);
		2056
1742	io.start (fd, ev::READ);	2057	io.start (fd, ev::READ);
1743	}	2058	}
1744		2059
1745		2060
1746	=head1 MACRO MAGIC	2061	=head1 MACRO MAGIC
1747		2062
1748	Libev can be compiled with a variety of options, the most fundemantal is	2063	Libev can be compiled with a variety of options, the most fundemantal is
1749	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2064	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
1750	callbacks have an initial C<struct ev_loop *> argument.	2065	callbacks have an initial C<struct ev_loop *> argument.
1751		2066
1752	To make it easier to write programs that cope with either variant, the	2067	To make it easier to write programs that cope with either variant, the
1753	following macros are defined:	2068	following macros are defined:
1754		2069
…		…
1787	Similar to the other two macros, this gives you the value of the default	2102	Similar to the other two macros, this gives you the value of the default
1788	loop, if multiple loops are supported ("ev loop default").	2103	loop, if multiple loops are supported ("ev loop default").
1789		2104
1790	=back	2105	=back
1791		2106
1792	Example: Declare and initialise a check watcher, working regardless of	2107	Example: Declare and initialise a check watcher, utilising the above
1793	wether multiple loops are supported or not.	2108	macros so it will work regardless of whether multiple loops are supported
		2109	or not.
1794		2110
1795	static void	2111	static void
1796	check_cb (EV_P_ ev_timer *w, int revents)	2112	check_cb (EV_P_ ev_timer *w, int revents)
1797	{	2113	{
1798	ev_check_stop (EV_A_ w);	2114	ev_check_stop (EV_A_ w);
…		…
1800		2116
1801	ev_check check;	2117	ev_check check;
1802	ev_check_init (&check, check_cb);	2118	ev_check_init (&check, check_cb);
1803	ev_check_start (EV_DEFAULT_ &check);	2119	ev_check_start (EV_DEFAULT_ &check);
1804	ev_loop (EV_DEFAULT_ 0);	2120	ev_loop (EV_DEFAULT_ 0);
1805
1806		2121
1807	=head1 EMBEDDING	2122	=head1 EMBEDDING
1808		2123
1809	Libev can (and often is) directly embedded into host	2124	Libev can (and often is) directly embedded into host
1810	applications. Examples of applications that embed it include the Deliantra	2125	applications. Examples of applications that embed it include the Deliantra
…		…
1850	ev_vars.h	2165	ev_vars.h
1851	ev_wrap.h	2166	ev_wrap.h
1852		2167
1853	ev_win32.c required on win32 platforms only	2168	ev_win32.c required on win32 platforms only
1854		2169
1855	ev_select.c only when select backend is enabled (which is by default)	2170	ev_select.c only when select backend is enabled (which is enabled by default)
1856	ev_poll.c only when poll backend is enabled (disabled by default)	2171	ev_poll.c only when poll backend is enabled (disabled by default)
1857	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2172	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1858	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2173	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1859	ev_port.c only when the solaris port backend is enabled (disabled by default)	2174	ev_port.c only when the solaris port backend is enabled (disabled by default)
1860		2175
…		…
1985		2300
1986	=item EV_USE_DEVPOLL	2301	=item EV_USE_DEVPOLL
1987		2302
1988	reserved for future expansion, works like the USE symbols above.	2303	reserved for future expansion, works like the USE symbols above.
1989		2304
		2305	=item EV_USE_INOTIFY
		2306
		2307	If defined to be C<1>, libev will compile in support for the Linux inotify
		2308	interface to speed up C<ev_stat> watchers. Its actual availability will
		2309	be detected at runtime.
		2310
1990	=item EV_H	2311	=item EV_H
1991		2312
1992	The name of the F<ev.h> header file used to include it. The default if	2313	The name of the F<ev.h> header file used to include it. The default if
1993	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2314	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
1994	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2315	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
2017	will have the C<struct ev_loop *> as first argument, and you can create	2338	will have the C<struct ev_loop *> as first argument, and you can create
2018	additional independent event loops. Otherwise there will be no support	2339	additional independent event loops. Otherwise there will be no support
2019	for multiple event loops and there is no first event loop pointer	2340	for multiple event loops and there is no first event loop pointer
2020	argument. Instead, all functions act on the single default loop.	2341	argument. Instead, all functions act on the single default loop.
2021		2342
		2343	=item EV_MINPRI
		2344
		2345	=item EV_MAXPRI
		2346
		2347	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2348	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2349	provide for more priorities by overriding those symbols (usually defined
		2350	to be C<-2> and C<2>, respectively).
		2351
		2352	When doing priority-based operations, libev usually has to linearly search
		2353	all the priorities, so having many of them (hundreds) uses a lot of space
		2354	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2355	fine.
		2356
		2357	If your embedding app does not need any priorities, defining these both to
		2358	C<0> will save some memory and cpu.
		2359
2022	=item EV_PERIODIC_ENABLE	2360	=item EV_PERIODIC_ENABLE
2023		2361
2024	If undefined or defined to be C<1>, then periodic timers are supported. If	2362	If undefined or defined to be C<1>, then periodic timers are supported. If
2025	defined to be C<0>, then they are not. Disabling them saves a few kB of	2363	defined to be C<0>, then they are not. Disabling them saves a few kB of
2026	code.	2364	code.
2027		2365
		2366	=item EV_IDLE_ENABLE
		2367
		2368	If undefined or defined to be C<1>, then idle watchers are supported. If
		2369	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2370	code.
		2371
2028	=item EV_EMBED_ENABLE	2372	=item EV_EMBED_ENABLE
2029		2373
2030	If undefined or defined to be C<1>, then embed watchers are supported. If	2374	If undefined or defined to be C<1>, then embed watchers are supported. If
2031	defined to be C<0>, then they are not.	2375	defined to be C<0>, then they are not.
2032		2376
…		…
2049	=item EV_PID_HASHSIZE	2393	=item EV_PID_HASHSIZE
2050		2394
2051	C<ev_child> watchers use a small hash table to distribute workload by	2395	C<ev_child> watchers use a small hash table to distribute workload by
2052	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	2396	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
2053	than enough. If you need to manage thousands of children you might want to	2397	than enough. If you need to manage thousands of children you might want to
2054	increase this value.	2398	increase this value (I<must> be a power of two).
		2399
		2400	=item EV_INOTIFY_HASHSIZE
		2401
		2402	C<ev_staz> watchers use a small hash table to distribute workload by
		2403	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2404	usually more than enough. If you need to manage thousands of C<ev_stat>
		2405	watchers you might want to increase this value (I<must> be a power of
		2406	two).
2055		2407
2056	=item EV_COMMON	2408	=item EV_COMMON
2057		2409
2058	By default, all watchers have a C<void *data> member. By redefining	2410	By default, all watchers have a C<void *data> member. By redefining
2059	this macro to a something else you can include more and other types of	2411	this macro to a something else you can include more and other types of
…		…
2088	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2440	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2089	will be compiled. It is pretty complex because it provides its own header	2441	will be compiled. It is pretty complex because it provides its own header
2090	file.	2442	file.
2091		2443
2092	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2444	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2093	that everybody includes and which overrides some autoconf choices:	2445	that everybody includes and which overrides some configure choices:
2094		2446
		2447	#define EV_MINIMAL 1
2095	#define EV_USE_POLL 0	2448	#define EV_USE_POLL 0
2096	#define EV_MULTIPLICITY 0	2449	#define EV_MULTIPLICITY 0
2097	#define EV_PERIODICS 0	2450	#define EV_PERIODIC_ENABLE 0
		2451	#define EV_STAT_ENABLE 0
		2452	#define EV_FORK_ENABLE 0
2098	#define EV_CONFIG_H <config.h>	2453	#define EV_CONFIG_H <config.h>
		2454	#define EV_MINPRI 0
		2455	#define EV_MAXPRI 0
2099		2456
2100	#include "ev++.h"	2457	#include "ev++.h"
2101		2458
2102	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2459	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2103		2460
…		…
2109		2466
2110	In this section the complexities of (many of) the algorithms used inside	2467	In this section the complexities of (many of) the algorithms used inside
2111	libev will be explained. For complexity discussions about backends see the	2468	libev will be explained. For complexity discussions about backends see the
2112	documentation for C<ev_default_init>.	2469	documentation for C<ev_default_init>.
2113		2470
		2471	All of the following are about amortised time: If an array needs to be
		2472	extended, libev needs to realloc and move the whole array, but this
		2473	happens asymptotically never with higher number of elements, so O(1) might
		2474	mean it might do a lengthy realloc operation in rare cases, but on average
		2475	it is much faster and asymptotically approaches constant time.
		2476
2114	=over 4	2477	=over 4
2115		2478
2116	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2479	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2117		2480
		2481	This means that, when you have a watcher that triggers in one hour and
		2482	there are 100 watchers that would trigger before that then inserting will
		2483	have to skip those 100 watchers.
		2484
2118	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2485	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2119		2486
		2487	That means that for changing a timer costs less than removing/adding them
		2488	as only the relative motion in the event queue has to be paid for.
		2489
2120	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2490	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2121		2491
		2492	These just add the watcher into an array or at the head of a list.
2122	=item Stopping check/prepare/idle watchers: O(1)	2493	=item Stopping check/prepare/idle watchers: O(1)
2123		2494
2124	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2495	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2496
		2497	These watchers are stored in lists then need to be walked to find the
		2498	correct watcher to remove. The lists are usually short (you don't usually
		2499	have many watchers waiting for the same fd or signal).
2125		2500
2126	=item Finding the next timer per loop iteration: O(1)	2501	=item Finding the next timer per loop iteration: O(1)
2127		2502
2128	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2503	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2129		2504
		2505	A change means an I/O watcher gets started or stopped, which requires
		2506	libev to recalculate its status (and possibly tell the kernel).
		2507
2130	=item Activating one watcher: O(1)	2508	=item Activating one watcher: O(1)
2131		2509
		2510	=item Priority handling: O(number_of_priorities)
		2511
		2512	Priorities are implemented by allocating some space for each
		2513	priority. When doing priority-based operations, libev usually has to
		2514	linearly search all the priorities.
		2515
2132	=back	2516	=back
2133		2517
2134		2518
2135	=head1 AUTHOR	2519	=head1 AUTHOR
2136		2520

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing libev/ev.pod (file contents): Revision 1.54 by root, Tue Nov 27 20:26:51 2007 UTC vs. Revision 1.83 by root, Wed Dec 12 17:55:31 2007 UTC

Diff Legend

Comparing libev/ev.pod (file contents):
Revision 1.54 by root, Tue Nov 27 20:26:51 2007 UTC vs.
Revision 1.83 by root, Wed Dec 12 17:55:31 2007 UTC