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

Comparing libev/ev.pod (file contents):
Revision 1.55 by root, Tue Nov 27 20:38:07 2007 UTC vs.
Revision 1.85 by root, Mon Dec 17 07:24:12 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
…		…
826	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
827	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.
828		909
829	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
830	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
831	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
832	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
833	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
834		939
835	=over 4	940	=over 4
836		941
837	=item ev_io_init (ev_io *, callback, int fd, int events)	942	=item ev_io_init (ev_io *, callback, int fd, int events)
838		943
…		…
892		997
893	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,
894	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
895	order of execution is undefined.	1000	order of execution is undefined.
896		1001
		1002	=head3 Watcher-Specific Functions and Data Members
		1003
897	=over 4	1004	=over 4
898		1005
899	=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)
900		1007
901	=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)
…		…
914	=item ev_timer_again (loop)	1021	=item ev_timer_again (loop)
915		1022
916	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
917	repeating. The exact semantics are:	1024	repeating. The exact semantics are:
918		1025
		1026	If the timer is pending, its pending status is cleared.
		1027
919	If the timer is started but nonrepeating, stop it.	1028	If the timer is started but nonrepeating, stop it (as if it timed out).
920		1029
921	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
922	value), or reset the running timer to the repeat value.	1031	C<repeat> value), or reset the running timer to the C<repeat> value.
923		1032
924	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
925	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
926	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
927	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
928	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
929	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
930	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
931	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
932	need be.	1041	automatically restart it if need be.
933		1042
934	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>
935	and only ever use the C<repeat> value:	1044	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
936		1045
937	ev_timer_init (timer, callback, 0., 5.);	1046	ev_timer_init (timer, callback, 0., 5.);
938	ev_timer_again (loop, timer);	1047	ev_timer_again (loop, timer);
939	...	1048	...
940	timer->again = 17.;	1049	timer->again = 17.;
941	ev_timer_again (loop, timer);	1050	ev_timer_again (loop, timer);
942	...	1051	...
943	timer->again = 10.;	1052	timer->again = 10.;
944	ev_timer_again (loop, timer);	1053	ev_timer_again (loop, timer);
945		1054
946	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
947	to modify its timeout value.	1056	you want to modify its timeout value.
948		1057
949	=item ev_tstamp repeat [read-write]	1058	=item ev_tstamp repeat [read-write]
950		1059
951	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
952	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),
…		…
994	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
995	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
996	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 ()
997	+ 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
998	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
999	roughly 10 seconds later and of course not if you reset your system time	1108	roughly 10 seconds later).
1000	again).
1001		1109
1002	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
1003	triggering an event on eahc midnight, local time.	1111	triggering an event on each midnight, local time or other, complicated,
		1112	rules.
1004		1113
1005	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
1006	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
1007	during the same loop iteration then order of execution is undefined.	1116	during the same loop iteration then order of execution is undefined.
1008		1117
		1118	=head3 Watcher-Specific Functions and Data Members
		1119
1009	=over 4	1120	=over 4
1010		1121
1011	=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)
1012		1123
1013	=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)
…		…
1015	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
1016	operation, and we will explain them from simplest to complex:	1127	operation, and we will explain them from simplest to complex:
1017		1128
1018	=over 4	1129	=over 4
1019		1130
1020	=item * absolute timer (interval = reschedule_cb = 0)	1131	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1021		1132
1022	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
1023	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,
1024	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
1025	system time reaches or surpasses this time.	1136	system time reaches or surpasses this time.
1026		1137
1027	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1138	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1028		1139
1029	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
1030	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)
1031	of any time jumps.	1142	and then repeat, regardless of any time jumps.
1032		1143
1033	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
1034	time:	1145	time:
1035		1146
1036	ev_periodic_set (&periodic, 0., 3600., 0);	1147	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1042		1153
1043	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
1044	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
1045	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.
1046		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
1047	=item * manual reschedule mode (reschedule_cb = callback)	1162	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1048		1163
1049	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
1050	ignored. Instead, each time the periodic watcher gets scheduled, the	1165	ignored. Instead, each time the periodic watcher gets scheduled, the
1051	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
1052	current time as second argument.	1167	current time as second argument.
1053		1168
1054	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,
1055	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,
1056	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
1057	starting a prepare watcher).	1172	starting an C<ev_prepare> watcher, which is legal).
1058		1173
1059	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,
1060	ev_tstamp now)>, e.g.:	1175	ev_tstamp now)>, e.g.:
1061		1176
1062	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)
…		…
1085	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
1086	when you changed some parameters or the reschedule callback would return	1201	when you changed some parameters or the reschedule callback would return
1087	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
1088	program when the crontabs have changed).	1203	program when the crontabs have changed).
1089		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.
		1212
1090	=item ev_tstamp interval [read-write]	1213	=item ev_tstamp interval [read-write]
1091		1214
1092	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
1093	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
1094	called.	1217	called.
…		…
1096	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]	1219	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
1097		1220
1098	The current reschedule callback, or C<0>, if this functionality is	1221	The current reschedule callback, or C<0>, if this functionality is
1099	switched off. Can be changed any time, but changes only take effect when	1222	switched off. Can be changed any time, but changes only take effect when
1100	the periodic timer fires or C<ev_periodic_again> is being called.	1223	the periodic timer fires or C<ev_periodic_again> is being called.
		1224
		1225	=item ev_tstamp at [read-only]
		1226
		1227	When active, contains the absolute time that the watcher is supposed to
		1228	trigger next.
1101		1229
1102	=back	1230	=back
1103		1231
1104	Example: Call a callback every hour, or, more precisely, whenever the	1232	Example: Call a callback every hour, or, more precisely, whenever the
1105	system clock is divisible by 3600. The callback invocation times have	1233	system clock is divisible by 3600. The callback invocation times have
…		…
1147	with the kernel (thus it coexists with your own signal handlers as long	1275	with the kernel (thus it coexists with your own signal handlers as long
1148	as you don't register any with libev). Similarly, when the last signal	1276	as you don't register any with libev). Similarly, when the last signal
1149	watcher for a signal is stopped libev will reset the signal handler to	1277	watcher for a signal is stopped libev will reset the signal handler to
1150	SIG_DFL (regardless of what it was set to before).	1278	SIG_DFL (regardless of what it was set to before).
1151		1279
		1280	=head3 Watcher-Specific Functions and Data Members
		1281
1152	=over 4	1282	=over 4
1153		1283
1154	=item ev_signal_init (ev_signal *, callback, int signum)	1284	=item ev_signal_init (ev_signal *, callback, int signum)
1155		1285
1156	=item ev_signal_set (ev_signal *, int signum)	1286	=item ev_signal_set (ev_signal *, int signum)
…		…
1167		1297
1168	=head2 C<ev_child> - watch out for process status changes	1298	=head2 C<ev_child> - watch out for process status changes
1169		1299
1170	Child watchers trigger when your process receives a SIGCHLD in response to	1300	Child watchers trigger when your process receives a SIGCHLD in response to
1171	some child status changes (most typically when a child of yours dies).	1301	some child status changes (most typically when a child of yours dies).
		1302
		1303	=head3 Watcher-Specific Functions and Data Members
1172		1304
1173	=over 4	1305	=over 4
1174		1306
1175	=item ev_child_init (ev_child *, callback, int pid)	1307	=item ev_child_init (ev_child *, callback, int pid)
1176		1308
…		…
1221	not exist" is a status change like any other. The condition "path does	1353	not exist" is a status change like any other. The condition "path does
1222	not exist" is signified by the C<st_nlink> field being zero (which is	1354	not exist" is signified by the C<st_nlink> field being zero (which is
1223	otherwise always forced to be at least one) and all the other fields of	1355	otherwise always forced to be at least one) and all the other fields of
1224	the stat buffer having unspecified contents.	1356	the stat buffer having unspecified contents.
1225		1357
		1358	The path I<should> be absolute and I<must not> end in a slash. If it is
		1359	relative and your working directory changes, the behaviour is undefined.
		1360
1226	Since there is no standard to do this, the portable implementation simply	1361	Since there is no standard to do this, the portable implementation simply
1227	calls C<stat (2)> regulalry on the path to see if it changed somehow. You	1362	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1228	can specify a recommended polling interval for this case. If you specify	1363	can specify a recommended polling interval for this case. If you specify
1229	a polling interval of C<0> (highly recommended!) then a I<suitable,	1364	a polling interval of C<0> (highly recommended!) then a I<suitable,
1230	unspecified default> value will be used (which you can expect to be around	1365	unspecified default> value will be used (which you can expect to be around
1231	five seconds, although this might change dynamically). Libev will also	1366	five seconds, although this might change dynamically). Libev will also
1232	impose a minimum interval which is currently around C<0.1>, but thats	1367	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1234		1369
1235	This watcher type is not meant for massive numbers of stat watchers,	1370	This watcher type is not meant for massive numbers of stat watchers,
1236	as even with OS-supported change notifications, this can be	1371	as even with OS-supported change notifications, this can be
1237	resource-intensive.	1372	resource-intensive.
1238		1373
1239	At the time of this writing, no specific OS backends are implemented, but	1374	At the time of this writing, only the Linux inotify interface is
1240	if demand increases, at least a kqueue and inotify backend will be added.	1375	implemented (implementing kqueue support is left as an exercise for the
		1376	reader). Inotify will be used to give hints only and should not change the
		1377	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1378	to fall back to regular polling again even with inotify, but changes are
		1379	usually detected immediately, and if the file exists there will be no
		1380	polling.
		1381
		1382	=head3 Watcher-Specific Functions and Data Members
1241		1383
1242	=over 4	1384	=over 4
1243		1385
1244	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1386	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1245		1387
…		…
1309	ev_stat_start (loop, &passwd);	1451	ev_stat_start (loop, &passwd);
1310		1452
1311		1453
1312	=head2 C<ev_idle> - when you've got nothing better to do...	1454	=head2 C<ev_idle> - when you've got nothing better to do...
1313		1455
1314	Idle watchers trigger events when there are no other events are pending	1456	Idle watchers trigger events when no other events of the same or higher
1315	(prepare, check and other idle watchers do not count). That is, as long	1457	priority are pending (prepare, check and other idle watchers do not
1316	as your process is busy handling sockets or timeouts (or even signals,	1458	count).
1317	imagine) it will not be triggered. But when your process is idle all idle	1459
1318	watchers are being called again and again, once per event loop iteration -	1460	That is, as long as your process is busy handling sockets or timeouts
		1461	(or even signals, imagine) of the same or higher priority it will not be
		1462	triggered. But when your process is idle (or only lower-priority watchers
		1463	are pending), the idle watchers are being called once per event loop
1319	until stopped, that is, or your process receives more events and becomes	1464	iteration - until stopped, that is, or your process receives more events
1320	busy.	1465	and becomes busy again with higher priority stuff.
1321		1466
1322	The most noteworthy effect is that as long as any idle watchers are	1467	The most noteworthy effect is that as long as any idle watchers are
1323	active, the process will not block when waiting for new events.	1468	active, the process will not block when waiting for new events.
1324		1469
1325	Apart from keeping your process non-blocking (which is a useful	1470	Apart from keeping your process non-blocking (which is a useful
1326	effect on its own sometimes), idle watchers are a good place to do	1471	effect on its own sometimes), idle watchers are a good place to do
1327	"pseudo-background processing", or delay processing stuff to after the	1472	"pseudo-background processing", or delay processing stuff to after the
1328	event loop has handled all outstanding events.	1473	event loop has handled all outstanding events.
		1474
		1475	=head3 Watcher-Specific Functions and Data Members
1329		1476
1330	=over 4	1477	=over 4
1331		1478
1332	=item ev_idle_init (ev_signal *, callback)	1479	=item ev_idle_init (ev_signal *, callback)
1333		1480
…		…
1391	with priority higher than or equal to the event loop and one coroutine	1538	with priority higher than or equal to the event loop and one coroutine
1392	of lower priority, but only once, using idle watchers to keep the event	1539	of lower priority, but only once, using idle watchers to keep the event
1393	loop from blocking if lower-priority coroutines are active, thus mapping	1540	loop from blocking if lower-priority coroutines are active, thus mapping
1394	low-priority coroutines to idle/background tasks).	1541	low-priority coroutines to idle/background tasks).
1395		1542
		1543	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1544	priority, to ensure that they are being run before any other watchers
		1545	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1546	too) should not activate ("feed") events into libev. While libev fully
		1547	supports this, they will be called before other C<ev_check> watchers did
		1548	their job. As C<ev_check> watchers are often used to embed other event
		1549	loops those other event loops might be in an unusable state until their
		1550	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1551	others).
		1552
		1553	=head3 Watcher-Specific Functions and Data Members
		1554
1396	=over 4	1555	=over 4
1397		1556
1398	=item ev_prepare_init (ev_prepare *, callback)	1557	=item ev_prepare_init (ev_prepare *, callback)
1399		1558
1400	=item ev_check_init (ev_check *, callback)	1559	=item ev_check_init (ev_check *, callback)
…		…
1403	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1562	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1404	macros, but using them is utterly, utterly and completely pointless.	1563	macros, but using them is utterly, utterly and completely pointless.
1405		1564
1406	=back	1565	=back
1407		1566
1408	Example: To include a library such as adns, you would add IO watchers	1567	There are a number of principal ways to embed other event loops or modules
1409	and a timeout watcher in a prepare handler, as required by libadns, and	1568	into libev. Here are some ideas on how to include libadns into libev
		1569	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1570	use for an actually working example. Another Perl module named C<EV::Glib>
		1571	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1572	into the Glib event loop).
		1573
		1574	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1410	in a check watcher, destroy them and call into libadns. What follows is	1575	and in a check watcher, destroy them and call into libadns. What follows
1411	pseudo-code only of course:	1576	is pseudo-code only of course. This requires you to either use a low
		1577	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1578	the callbacks for the IO/timeout watchers might not have been called yet.
1412		1579
1413	static ev_io iow [nfd];	1580	static ev_io iow [nfd];
1414	static ev_timer tw;	1581	static ev_timer tw;
1415		1582
1416	static void	1583	static void
1417	io_cb (ev_loop loop, ev_io w, int revents)	1584	io_cb (ev_loop loop, ev_io w, int revents)
1418	{	1585	{
1419	// set the relevant poll flags
1420	// could also call adns_processreadable etc. here
1421	struct pollfd fd = (struct pollfd )w->data;
1422	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1423	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1424	}	1586	}
1425		1587
1426	// create io watchers for each fd and a timer before blocking	1588	// create io watchers for each fd and a timer before blocking
1427	static void	1589	static void
1428	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1590	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1429	{	1591	{
1430	int timeout = 3600000;truct pollfd fds [nfd];	1592	int timeout = 3600000;
		1593	struct pollfd fds [nfd];
1431	// actual code will need to loop here and realloc etc.	1594	// actual code will need to loop here and realloc etc.
1432	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1595	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1433		1596
1434	/* the callback is illegal, but won't be called as we stop during check */	1597	/* the callback is illegal, but won't be called as we stop during check */
1435	ev_timer_init (&tw, 0, timeout * 1e-3);	1598	ev_timer_init (&tw, 0, timeout * 1e-3);
1436	ev_timer_start (loop, &tw);	1599	ev_timer_start (loop, &tw);
1437		1600
1438	// create on ev_io per pollfd	1601	// create one ev_io per pollfd
1439	for (int i = 0; i < nfd; ++i)	1602	for (int i = 0; i < nfd; ++i)
1440	{	1603	{
1441	ev_io_init (iow + i, io_cb, fds [i].fd,	1604	ev_io_init (iow + i, io_cb, fds [i].fd,
1442	((fds [i].events & POLLIN ? EV_READ : 0)	1605	((fds [i].events & POLLIN ? EV_READ : 0)
1443	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1606	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1444		1607
1445	fds [i].revents = 0;	1608	fds [i].revents = 0;
1446	iow [i].data = fds + i;
1447	ev_io_start (loop, iow + i);	1609	ev_io_start (loop, iow + i);
1448	}	1610	}
1449	}	1611	}
1450		1612
1451	// stop all watchers after blocking	1613	// stop all watchers after blocking
…		…
1453	adns_check_cb (ev_loop loop, ev_check w, int revents)	1615	adns_check_cb (ev_loop loop, ev_check w, int revents)
1454	{	1616	{
1455	ev_timer_stop (loop, &tw);	1617	ev_timer_stop (loop, &tw);
1456		1618
1457	for (int i = 0; i < nfd; ++i)	1619	for (int i = 0; i < nfd; ++i)
		1620	{
		1621	// set the relevant poll flags
		1622	// could also call adns_processreadable etc. here
		1623	struct pollfd *fd = fds + i;
		1624	int revents = ev_clear_pending (iow + i);
		1625	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1626	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1627
		1628	// now stop the watcher
1458	ev_io_stop (loop, iow + i);	1629	ev_io_stop (loop, iow + i);
		1630	}
1459		1631
1460	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1632	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1633	}
		1634
		1635	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1636	in the prepare watcher and would dispose of the check watcher.
		1637
		1638	Method 3: If the module to be embedded supports explicit event
		1639	notification (adns does), you can also make use of the actual watcher
		1640	callbacks, and only destroy/create the watchers in the prepare watcher.
		1641
		1642	static void
		1643	timer_cb (EV_P_ ev_timer *w, int revents)
		1644	{
		1645	adns_state ads = (adns_state)w->data;
		1646	update_now (EV_A);
		1647
		1648	adns_processtimeouts (ads, &tv_now);
		1649	}
		1650
		1651	static void
		1652	io_cb (EV_P_ ev_io *w, int revents)
		1653	{
		1654	adns_state ads = (adns_state)w->data;
		1655	update_now (EV_A);
		1656
		1657	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1658	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1659	}
		1660
		1661	// do not ever call adns_afterpoll
		1662
		1663	Method 4: Do not use a prepare or check watcher because the module you
		1664	want to embed is too inflexible to support it. Instead, youc na override
		1665	their poll function. The drawback with this solution is that the main
		1666	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1667	this.
		1668
		1669	static gint
		1670	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1671	{
		1672	int got_events = 0;
		1673
		1674	for (n = 0; n < nfds; ++n)
		1675	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1676
		1677	if (timeout >= 0)
		1678	// create/start timer
		1679
		1680	// poll
		1681	ev_loop (EV_A_ 0);
		1682
		1683	// stop timer again
		1684	if (timeout >= 0)
		1685	ev_timer_stop (EV_A_ &to);
		1686
		1687	// stop io watchers again - their callbacks should have set
		1688	for (n = 0; n < nfds; ++n)
		1689	ev_io_stop (EV_A_ iow [n]);
		1690
		1691	return got_events;
1461	}	1692	}
1462		1693
1463		1694
1464	=head2 C<ev_embed> - when one backend isn't enough...	1695	=head2 C<ev_embed> - when one backend isn't enough...
1465		1696
…		…
1529	ev_embed_start (loop_hi, &embed);	1760	ev_embed_start (loop_hi, &embed);
1530	}	1761	}
1531	else	1762	else
1532	loop_lo = loop_hi;	1763	loop_lo = loop_hi;
1533		1764
		1765	=head3 Watcher-Specific Functions and Data Members
		1766
1534	=over 4	1767	=over 4
1535		1768
1536	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)	1769	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)
1537		1770
1538	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)	1771	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)
…		…
1564	event loop blocks next and before C<ev_check> watchers are being called,	1797	event loop blocks next and before C<ev_check> watchers are being called,
1565	and only in the child after the fork. If whoever good citizen calling	1798	and only in the child after the fork. If whoever good citizen calling
1566	C<ev_default_fork> cheats and calls it in the wrong process, the fork	1799	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1567	handlers will be invoked, too, of course.	1800	handlers will be invoked, too, of course.
1568		1801
		1802	=head3 Watcher-Specific Functions and Data Members
		1803
1569	=over 4	1804	=over 4
1570		1805
1571	=item ev_fork_init (ev_signal *, callback)	1806	=item ev_fork_init (ev_signal *, callback)
1572		1807
1573	Initialises and configures the fork watcher - it has no parameters of any	1808	Initialises and configures the fork watcher - it has no parameters of any
…		…
1669		1904
1670	To use it,	1905	To use it,
1671		1906
1672	#include <ev++.h>	1907	#include <ev++.h>
1673		1908
1674	(it is not installed by default). This automatically includes F<ev.h>	1909	This automatically includes F<ev.h> and puts all of its definitions (many
1675	and puts all of its definitions (many of them macros) into the global	1910	of them macros) into the global namespace. All C++ specific things are
1676	namespace. All C++ specific things are put into the C<ev> namespace.	1911	put into the C<ev> namespace. It should support all the same embedding
		1912	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1677		1913
1678	It should support all the same embedding options as F<ev.h>, most notably	1914	Care has been taken to keep the overhead low. The only data member the C++
1679	C<EV_MULTIPLICITY>.	1915	classes add (compared to plain C-style watchers) is the event loop pointer
		1916	that the watcher is associated with (or no additional members at all if
		1917	you disable C<EV_MULTIPLICITY> when embedding libev).
		1918
		1919	Currently, functions, and static and non-static member functions can be
		1920	used as callbacks. Other types should be easy to add as long as they only
		1921	need one additional pointer for context. If you need support for other
		1922	types of functors please contact the author (preferably after implementing
		1923	it).
1680		1924
1681	Here is a list of things available in the C<ev> namespace:	1925	Here is a list of things available in the C<ev> namespace:
1682		1926
1683	=over 4	1927	=over 4
1684		1928
…		…
1700		1944
1701	All of those classes have these methods:	1945	All of those classes have these methods:
1702		1946
1703	=over 4	1947	=over 4
1704		1948
1705	=item ev::TYPE::TYPE (object , object::method )	1949	=item ev::TYPE::TYPE ()
1706		1950
1707	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1951	=item ev::TYPE::TYPE (struct ev_loop *)
1708		1952
1709	=item ev::TYPE::~TYPE	1953	=item ev::TYPE::~TYPE
1710		1954
1711	The constructor takes a pointer to an object and a method pointer to	1955	The constructor (optionally) takes an event loop to associate the watcher
1712	the event handler callback to call in this class. The constructor calls	1956	with. If it is omitted, it will use C<EV_DEFAULT>.
1713	C<ev_init> for you, which means you have to call the C<set> method	1957
1714	before starting it. If you do not specify a loop then the constructor	1958	The constructor calls C<ev_init> for you, which means you have to call the
1715	automatically associates the default loop with this watcher.	1959	C<set> method before starting it.
		1960
		1961	It will not set a callback, however: You have to call the templated C<set>
		1962	method to set a callback before you can start the watcher.
		1963
		1964	(The reason why you have to use a method is a limitation in C++ which does
		1965	not allow explicit template arguments for constructors).
1716		1966
1717	The destructor automatically stops the watcher if it is active.	1967	The destructor automatically stops the watcher if it is active.
		1968
		1969	=item w->set<class, &class::method> (object *)
		1970
		1971	This method sets the callback method to call. The method has to have a
		1972	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1973	first argument and the C<revents> as second. The object must be given as
		1974	parameter and is stored in the C<data> member of the watcher.
		1975
		1976	This method synthesizes efficient thunking code to call your method from
		1977	the C callback that libev requires. If your compiler can inline your
		1978	callback (i.e. it is visible to it at the place of the C<set> call and
		1979	your compiler is good :), then the method will be fully inlined into the
		1980	thunking function, making it as fast as a direct C callback.
		1981
		1982	Example: simple class declaration and watcher initialisation
		1983
		1984	struct myclass
		1985	{
		1986	void io_cb (ev::io &w, int revents) { }
		1987	}
		1988
		1989	myclass obj;
		1990	ev::io iow;
		1991	iow.set <myclass, &myclass::io_cb> (&obj);
		1992
		1993	=item w->set<function> (void *data = 0)
		1994
		1995	Also sets a callback, but uses a static method or plain function as
		1996	callback. The optional C<data> argument will be stored in the watcher's
		1997	C<data> member and is free for you to use.
		1998
		1999	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2000
		2001	See the method-C<set> above for more details.
		2002
		2003	Example:
		2004
		2005	static void io_cb (ev::io &w, int revents) { }
		2006	iow.set <io_cb> ();
1718		2007
1719	=item w->set (struct ev_loop *)	2008	=item w->set (struct ev_loop *)
1720		2009
1721	Associates a different C<struct ev_loop> with this watcher. You can only	2010	Associates a different C<struct ev_loop> with this watcher. You can only
1722	do this when the watcher is inactive (and not pending either).	2011	do this when the watcher is inactive (and not pending either).
1723		2012
1724	=item w->set ([args])	2013	=item w->set ([args])
1725		2014
1726	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2015	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1727	called at least once. Unlike the C counterpart, an active watcher gets	2016	called at least once. Unlike the C counterpart, an active watcher gets
1728	automatically stopped and restarted.	2017	automatically stopped and restarted when reconfiguring it with this
		2018	method.
1729		2019
1730	=item w->start ()	2020	=item w->start ()
1731		2021
1732	Starts the watcher. Note that there is no C<loop> argument as the	2022	Starts the watcher. Note that there is no C<loop> argument, as the
1733	constructor already takes the loop.	2023	constructor already stores the event loop.
1734		2024
1735	=item w->stop ()	2025	=item w->stop ()
1736		2026
1737	Stops the watcher if it is active. Again, no C<loop> argument.	2027	Stops the watcher if it is active. Again, no C<loop> argument.
1738		2028
1739	=item w->again () C<ev::timer>, C<ev::periodic> only	2029	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1740		2030
1741	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2031	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1742	C<ev_TYPE_again> function.	2032	C<ev_TYPE_again> function.
1743		2033
1744	=item w->sweep () C<ev::embed> only	2034	=item w->sweep () (C<ev::embed> only)
1745		2035
1746	Invokes C<ev_embed_sweep>.	2036	Invokes C<ev_embed_sweep>.
1747		2037
1748	=item w->update () C<ev::stat> only	2038	=item w->update () (C<ev::stat> only)
1749		2039
1750	Invokes C<ev_stat_stat>.	2040	Invokes C<ev_stat_stat>.
1751		2041
1752	=back	2042	=back
1753		2043
…		…
1763		2053
1764	myclass ();	2054	myclass ();
1765	}	2055	}
1766		2056
1767	myclass::myclass (int fd)	2057	myclass::myclass (int fd)
1768	: io (this, &myclass::io_cb),
1769	idle (this, &myclass::idle_cb)
1770	{	2058	{
		2059	io .set <myclass, &myclass::io_cb > (this);
		2060	idle.set <myclass, &myclass::idle_cb> (this);
		2061
1771	io.start (fd, ev::READ);	2062	io.start (fd, ev::READ);
1772	}	2063	}
1773		2064
1774		2065
1775	=head1 MACRO MAGIC	2066	=head1 MACRO MAGIC
1776		2067
1777	Libev can be compiled with a variety of options, the most fundemantal is	2068	Libev can be compiled with a variety of options, the most fundamantal
1778	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2069	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1779	callbacks have an initial C<struct ev_loop *> argument.	2070	functions and callbacks have an initial C<struct ev_loop *> argument.
1780		2071
1781	To make it easier to write programs that cope with either variant, the	2072	To make it easier to write programs that cope with either variant, the
1782	following macros are defined:	2073	following macros are defined:
1783		2074
1784	=over 4	2075	=over 4
…		…
1816	Similar to the other two macros, this gives you the value of the default	2107	Similar to the other two macros, this gives you the value of the default
1817	loop, if multiple loops are supported ("ev loop default").	2108	loop, if multiple loops are supported ("ev loop default").
1818		2109
1819	=back	2110	=back
1820		2111
1821	Example: Declare and initialise a check watcher, working regardless of	2112	Example: Declare and initialise a check watcher, utilising the above
1822	wether multiple loops are supported or not.	2113	macros so it will work regardless of whether multiple loops are supported
		2114	or not.
1823		2115
1824	static void	2116	static void
1825	check_cb (EV_P_ ev_timer *w, int revents)	2117	check_cb (EV_P_ ev_timer *w, int revents)
1826	{	2118	{
1827	ev_check_stop (EV_A_ w);	2119	ev_check_stop (EV_A_ w);
…		…
1829		2121
1830	ev_check check;	2122	ev_check check;
1831	ev_check_init (&check, check_cb);	2123	ev_check_init (&check, check_cb);
1832	ev_check_start (EV_DEFAULT_ &check);	2124	ev_check_start (EV_DEFAULT_ &check);
1833	ev_loop (EV_DEFAULT_ 0);	2125	ev_loop (EV_DEFAULT_ 0);
1834
1835		2126
1836	=head1 EMBEDDING	2127	=head1 EMBEDDING
1837		2128
1838	Libev can (and often is) directly embedded into host	2129	Libev can (and often is) directly embedded into host
1839	applications. Examples of applications that embed it include the Deliantra	2130	applications. Examples of applications that embed it include the Deliantra
…		…
1879	ev_vars.h	2170	ev_vars.h
1880	ev_wrap.h	2171	ev_wrap.h
1881		2172
1882	ev_win32.c required on win32 platforms only	2173	ev_win32.c required on win32 platforms only
1883		2174
1884	ev_select.c only when select backend is enabled (which is by default)	2175	ev_select.c only when select backend is enabled (which is enabled by default)
1885	ev_poll.c only when poll backend is enabled (disabled by default)	2176	ev_poll.c only when poll backend is enabled (disabled by default)
1886	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2177	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1887	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2178	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1888	ev_port.c only when the solaris port backend is enabled (disabled by default)	2179	ev_port.c only when the solaris port backend is enabled (disabled by default)
1889		2180
…		…
2014		2305
2015	=item EV_USE_DEVPOLL	2306	=item EV_USE_DEVPOLL
2016		2307
2017	reserved for future expansion, works like the USE symbols above.	2308	reserved for future expansion, works like the USE symbols above.
2018		2309
		2310	=item EV_USE_INOTIFY
		2311
		2312	If defined to be C<1>, libev will compile in support for the Linux inotify
		2313	interface to speed up C<ev_stat> watchers. Its actual availability will
		2314	be detected at runtime.
		2315
2019	=item EV_H	2316	=item EV_H
2020		2317
2021	The name of the F<ev.h> header file used to include it. The default if	2318	The name of the F<ev.h> header file used to include it. The default if
2022	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2319	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
2023	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2320	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
2046	will have the C<struct ev_loop *> as first argument, and you can create	2343	will have the C<struct ev_loop *> as first argument, and you can create
2047	additional independent event loops. Otherwise there will be no support	2344	additional independent event loops. Otherwise there will be no support
2048	for multiple event loops and there is no first event loop pointer	2345	for multiple event loops and there is no first event loop pointer
2049	argument. Instead, all functions act on the single default loop.	2346	argument. Instead, all functions act on the single default loop.
2050		2347
		2348	=item EV_MINPRI
		2349
		2350	=item EV_MAXPRI
		2351
		2352	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2353	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2354	provide for more priorities by overriding those symbols (usually defined
		2355	to be C<-2> and C<2>, respectively).
		2356
		2357	When doing priority-based operations, libev usually has to linearly search
		2358	all the priorities, so having many of them (hundreds) uses a lot of space
		2359	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2360	fine.
		2361
		2362	If your embedding app does not need any priorities, defining these both to
		2363	C<0> will save some memory and cpu.
		2364
2051	=item EV_PERIODIC_ENABLE	2365	=item EV_PERIODIC_ENABLE
2052		2366
2053	If undefined or defined to be C<1>, then periodic timers are supported. If	2367	If undefined or defined to be C<1>, then periodic timers are supported. If
2054	defined to be C<0>, then they are not. Disabling them saves a few kB of	2368	defined to be C<0>, then they are not. Disabling them saves a few kB of
2055	code.	2369	code.
2056		2370
		2371	=item EV_IDLE_ENABLE
		2372
		2373	If undefined or defined to be C<1>, then idle watchers are supported. If
		2374	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2375	code.
		2376
2057	=item EV_EMBED_ENABLE	2377	=item EV_EMBED_ENABLE
2058		2378
2059	If undefined or defined to be C<1>, then embed watchers are supported. If	2379	If undefined or defined to be C<1>, then embed watchers are supported. If
2060	defined to be C<0>, then they are not.	2380	defined to be C<0>, then they are not.
2061		2381
…		…
2078	=item EV_PID_HASHSIZE	2398	=item EV_PID_HASHSIZE
2079		2399
2080	C<ev_child> watchers use a small hash table to distribute workload by	2400	C<ev_child> watchers use a small hash table to distribute workload by
2081	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	2401	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
2082	than enough. If you need to manage thousands of children you might want to	2402	than enough. If you need to manage thousands of children you might want to
2083	increase this value.	2403	increase this value (I<must> be a power of two).
		2404
		2405	=item EV_INOTIFY_HASHSIZE
		2406
		2407	C<ev_staz> watchers use a small hash table to distribute workload by
		2408	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2409	usually more than enough. If you need to manage thousands of C<ev_stat>
		2410	watchers you might want to increase this value (I<must> be a power of
		2411	two).
2084		2412
2085	=item EV_COMMON	2413	=item EV_COMMON
2086		2414
2087	By default, all watchers have a C<void *data> member. By redefining	2415	By default, all watchers have a C<void *data> member. By redefining
2088	this macro to a something else you can include more and other types of	2416	this macro to a something else you can include more and other types of
…		…
2117	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2445	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2118	will be compiled. It is pretty complex because it provides its own header	2446	will be compiled. It is pretty complex because it provides its own header
2119	file.	2447	file.
2120		2448
2121	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2449	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2122	that everybody includes and which overrides some autoconf choices:	2450	that everybody includes and which overrides some configure choices:
2123		2451
		2452	#define EV_MINIMAL 1
2124	#define EV_USE_POLL 0	2453	#define EV_USE_POLL 0
2125	#define EV_MULTIPLICITY 0	2454	#define EV_MULTIPLICITY 0
2126	#define EV_PERIODICS 0	2455	#define EV_PERIODIC_ENABLE 0
		2456	#define EV_STAT_ENABLE 0
		2457	#define EV_FORK_ENABLE 0
2127	#define EV_CONFIG_H <config.h>	2458	#define EV_CONFIG_H <config.h>
		2459	#define EV_MINPRI 0
		2460	#define EV_MAXPRI 0
2128		2461
2129	#include "ev++.h"	2462	#include "ev++.h"
2130		2463
2131	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2464	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2132		2465
…		…
2138		2471
2139	In this section the complexities of (many of) the algorithms used inside	2472	In this section the complexities of (many of) the algorithms used inside
2140	libev will be explained. For complexity discussions about backends see the	2473	libev will be explained. For complexity discussions about backends see the
2141	documentation for C<ev_default_init>.	2474	documentation for C<ev_default_init>.
2142		2475
		2476	All of the following are about amortised time: If an array needs to be
		2477	extended, libev needs to realloc and move the whole array, but this
		2478	happens asymptotically never with higher number of elements, so O(1) might
		2479	mean it might do a lengthy realloc operation in rare cases, but on average
		2480	it is much faster and asymptotically approaches constant time.
		2481
2143	=over 4	2482	=over 4
2144		2483
2145	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2484	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2146		2485
		2486	This means that, when you have a watcher that triggers in one hour and
		2487	there are 100 watchers that would trigger before that then inserting will
		2488	have to skip those 100 watchers.
		2489
2147	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2490	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2148		2491
		2492	That means that for changing a timer costs less than removing/adding them
		2493	as only the relative motion in the event queue has to be paid for.
		2494
2149	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2495	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2150		2496
		2497	These just add the watcher into an array or at the head of a list.
2151	=item Stopping check/prepare/idle watchers: O(1)	2498	=item Stopping check/prepare/idle watchers: O(1)
2152		2499
2153	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2500	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2501
		2502	These watchers are stored in lists then need to be walked to find the
		2503	correct watcher to remove. The lists are usually short (you don't usually
		2504	have many watchers waiting for the same fd or signal).
2154		2505
2155	=item Finding the next timer per loop iteration: O(1)	2506	=item Finding the next timer per loop iteration: O(1)
2156		2507
2157	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2508	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2158		2509
		2510	A change means an I/O watcher gets started or stopped, which requires
		2511	libev to recalculate its status (and possibly tell the kernel).
		2512
2159	=item Activating one watcher: O(1)	2513	=item Activating one watcher: O(1)
2160		2514
		2515	=item Priority handling: O(number_of_priorities)
		2516
		2517	Priorities are implemented by allocating some space for each
		2518	priority. When doing priority-based operations, libev usually has to
		2519	linearly search all the priorities.
		2520
2161	=back	2521	=back
2162		2522
2163		2523
2164	=head1 AUTHOR	2524	=head1 AUTHOR
2165		2525

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Comparing libev/ev.pod (file contents): Revision 1.55 by root, Tue Nov 27 20:38:07 2007 UTC vs. Revision 1.85 by root, Mon Dec 17 07:24:12 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.55 by root, Tue Nov 27 20:38:07 2007 UTC vs.
Revision 1.85 by root, Mon Dec 17 07:24:12 2007 UTC