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

Comparing libev/ev.pod (file contents):
Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC vs.
Revision 1.86 by root, Tue Dec 18 01:20:33 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
…		…
94	Libev represents time as a single floating point number, representing the	98	Libev represents time as a single floating point number, representing the
95	(fractional) number of seconds since the (POSIX) epoch (somewhere near	99	(fractional) number of seconds since the (POSIX) epoch (somewhere near
96	the beginning of 1970, details are complicated, don't ask). This type is	100	the beginning of 1970, details are complicated, don't ask). This type is
97	called C<ev_tstamp>, which is what you should use too. It usually aliases	101	called C<ev_tstamp>, which is what you should use too. It usually aliases
98	to the C<double> type in C, and when you need to do any calculations on	102	to the C<double> type in C, and when you need to do any calculations on
99	it, you should treat it as such.	103	it, you should treat it as some floatingpoint value. Unlike the name
		104	component C<stamp> might indicate, it is also used for time differences
		105	throughout libev.
100		106
101	=head1 GLOBAL FUNCTIONS	107	=head1 GLOBAL FUNCTIONS
102		108
103	These functions can be called anytime, even before initialising the	109	These functions can be called anytime, even before initialising the
104	library in any way.	110	library in any way.
…		…
113		119
114	=item int ev_version_major ()	120	=item int ev_version_major ()
115		121
116	=item int ev_version_minor ()	122	=item int ev_version_minor ()
117		123
118	You can find out the major and minor version numbers of the library	124	You can find out the major and minor ABI version numbers of the library
119	you linked against by calling the functions C<ev_version_major> and	125	you linked against by calling the functions C<ev_version_major> and
120	C<ev_version_minor>. If you want, you can compare against the global	126	C<ev_version_minor>. If you want, you can compare against the global
121	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the	127	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
122	version of the library your program was compiled against.	128	version of the library your program was compiled against.
123		129
		130	These version numbers refer to the ABI version of the library, not the
		131	release version.
		132
124	Usually, it's a good idea to terminate if the major versions mismatch,	133	Usually, it's a good idea to terminate if the major versions mismatch,
125	as this indicates an incompatible change. Minor versions are usually	134	as this indicates an incompatible change. Minor versions are usually
126	compatible to older versions, so a larger minor version alone is usually	135	compatible to older versions, so a larger minor version alone is usually
127	not a problem.	136	not a problem.
128		137
129	Example: Make sure we haven't accidentally been linked against the wrong	138	Example: Make sure we haven't accidentally been linked against the wrong
130	version.	139	version.
…		…
163	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	172	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
164	recommended ones.	173	recommended ones.
165		174
166	See the description of C<ev_embed> watchers for more info.	175	See the description of C<ev_embed> watchers for more info.
167		176
168	=item ev_set_allocator (void (cb)(void *ptr, size_t size))	177	=item ev_set_allocator (void (cb)(void *ptr, long size))
169		178
170	Sets the allocation function to use (the prototype and semantics are	179	Sets the allocation function to use (the prototype is similar - the
171	identical to the realloc C function). It is used to allocate and free	180	semantics is identical - to the realloc C function). It is used to
172	memory (no surprises here). If it returns zero when memory needs to be	181	allocate and free memory (no surprises here). If it returns zero when
173	allocated, the library might abort or take some potentially destructive	182	memory needs to be allocated, the library might abort or take some
174	action. The default is your system realloc function.	183	potentially destructive action. The default is your system realloc
		184	function.
175		185
176	You could override this function in high-availability programs to, say,	186	You could override this function in high-availability programs to, say,
177	free some memory if it cannot allocate memory, to use a special allocator,	187	free some memory if it cannot allocate memory, to use a special allocator,
178	or even to sleep a while and retry until some memory is available.	188	or even to sleep a while and retry until some memory is available.
179		189
…		…
265	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	275	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
266	override the flags completely if it is found in the environment. This is	276	override the flags completely if it is found in the environment. This is
267	useful to try out specific backends to test their performance, or to work	277	useful to try out specific backends to test their performance, or to work
268	around bugs.	278	around bugs.
269		279
		280	=item C<EVFLAG_FORKCHECK>
		281
		282	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		283	a fork, you can also make libev check for a fork in each iteration by
		284	enabling this flag.
		285
		286	This works by calling C<getpid ()> on every iteration of the loop,
		287	and thus this might slow down your event loop if you do a lot of loop
		288	iterations and little real work, but is usually not noticeable (on my
		289	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		290	without a syscall and thus I<very> fast, but my Linux system also has
		291	C<pthread_atfork> which is even faster).
		292
		293	The big advantage of this flag is that you can forget about fork (and
		294	forget about forgetting to tell libev about forking) when you use this
		295	flag.
		296
		297	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		298	environment variable.
		299
270	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	300	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
271		301
272	This is your standard select(2) backend. Not I<completely> standard, as	302	This is your standard select(2) backend. Not I<completely> standard, as
273	libev tries to roll its own fd_set with no limits on the number of fds,	303	libev tries to roll its own fd_set with no limits on the number of fds,
274	but if that fails, expect a fairly low limit on the number of fds when	304	but if that fails, expect a fairly low limit on the number of fds when
…		…
409		439
410	Like C<ev_default_fork>, but acts on an event loop created by	440	Like C<ev_default_fork>, but acts on an event loop created by
411	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	441	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
412	after fork, and how you do this is entirely your own problem.	442	after fork, and how you do this is entirely your own problem.
413		443
		444	=item unsigned int ev_loop_count (loop)
		445
		446	Returns the count of loop iterations for the loop, which is identical to
		447	the number of times libev did poll for new events. It starts at C<0> and
		448	happily wraps around with enough iterations.
		449
		450	This value can sometimes be useful as a generation counter of sorts (it
		451	"ticks" the number of loop iterations), as it roughly corresponds with
		452	C<ev_prepare> and C<ev_check> calls.
		453
414	=item unsigned int ev_backend (loop)	454	=item unsigned int ev_backend (loop)
415		455
416	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	456	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
417	use.	457	use.
418		458
…		…
451	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	491	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
452	usually a better approach for this kind of thing.	492	usually a better approach for this kind of thing.
453		493
454	Here are the gory details of what C<ev_loop> does:	494	Here are the gory details of what C<ev_loop> does:
455		495
		496	- Before the first iteration, call any pending watchers.
456	* If there are no active watchers (reference count is zero), return.	497	* If there are no active watchers (reference count is zero), return.
457	- Queue prepare watchers and then call all outstanding watchers.	498	- Queue all prepare watchers and then call all outstanding watchers.
458	- If we have been forked, recreate the kernel state.	499	- If we have been forked, recreate the kernel state.
459	- Update the kernel state with all outstanding changes.	500	- Update the kernel state with all outstanding changes.
460	- Update the "event loop time".	501	- Update the "event loop time".
461	- Calculate for how long to block.	502	- Calculate for how long to block.
462	- Block the process, waiting for any events.	503	- Block the process, waiting for any events.
…		…
701	=item bool ev_is_pending (ev_TYPE *watcher)	742	=item bool ev_is_pending (ev_TYPE *watcher)
702		743
703	Returns a true value iff the watcher is pending, (i.e. it has outstanding	744	Returns a true value iff the watcher is pending, (i.e. it has outstanding
704	events but its callback has not yet been invoked). As long as a watcher	745	events but its callback has not yet been invoked). As long as a watcher
705	is pending (but not active) you must not call an init function on it (but	746	is pending (but not active) you must not call an init function on it (but
706	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	747	C<ev_TYPE_set> is safe), you must not change its priority, and you must
707	libev (e.g. you cnanot C<free ()> it).	748	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		749	it).
708		750
709	=item callback ev_cb (ev_TYPE *watcher)	751	=item callback ev_cb (ev_TYPE *watcher)
710		752
711	Returns the callback currently set on the watcher.	753	Returns the callback currently set on the watcher.
712		754
713	=item ev_cb_set (ev_TYPE *watcher, callback)	755	=item ev_cb_set (ev_TYPE *watcher, callback)
714		756
715	Change the callback. You can change the callback at virtually any time	757	Change the callback. You can change the callback at virtually any time
716	(modulo threads).	758	(modulo threads).
		759
		760	=item ev_set_priority (ev_TYPE *watcher, priority)
		761
		762	=item int ev_priority (ev_TYPE *watcher)
		763
		764	Set and query the priority of the watcher. The priority is a small
		765	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		766	(default: C<-2>). Pending watchers with higher priority will be invoked
		767	before watchers with lower priority, but priority will not keep watchers
		768	from being executed (except for C<ev_idle> watchers).
		769
		770	This means that priorities are I<only> used for ordering callback
		771	invocation after new events have been received. This is useful, for
		772	example, to reduce latency after idling, or more often, to bind two
		773	watchers on the same event and make sure one is called first.
		774
		775	If you need to suppress invocation when higher priority events are pending
		776	you need to look at C<ev_idle> watchers, which provide this functionality.
		777
		778	You I<must not> change the priority of a watcher as long as it is active or
		779	pending.
		780
		781	The default priority used by watchers when no priority has been set is
		782	always C<0>, which is supposed to not be too high and not be too low :).
		783
		784	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		785	fine, as long as you do not mind that the priority value you query might
		786	or might not have been adjusted to be within valid range.
		787
		788	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		789
		790	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		791	C<loop> nor C<revents> need to be valid as long as the watcher callback
		792	can deal with that fact.
		793
		794	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		795
		796	If the watcher is pending, this function returns clears its pending status
		797	and returns its C<revents> bitset (as if its callback was invoked). If the
		798	watcher isn't pending it does nothing and returns C<0>.
717		799
718	=back	800	=back
719		801
720		802
721	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	803	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
827	it is best to always use non-blocking I/O: An extra C<read>(2) returning	909	it is best to always use non-blocking I/O: An extra C<read>(2) returning
828	C<EAGAIN> is far preferable to a program hanging until some data arrives.	910	C<EAGAIN> is far preferable to a program hanging until some data arrives.
829		911
830	If you cannot run the fd in non-blocking mode (for example you should not	912	If you cannot run the fd in non-blocking mode (for example you should not
831	play around with an Xlib connection), then you have to seperately re-test	913	play around with an Xlib connection), then you have to seperately re-test
832	wether a file descriptor is really ready with a known-to-be good interface	914	whether a file descriptor is really ready with a known-to-be good interface
833	such as poll (fortunately in our Xlib example, Xlib already does this on	915	such as poll (fortunately in our Xlib example, Xlib already does this on
834	its own, so its quite safe to use).	916	its own, so its quite safe to use).
		917
		918	=head3 The special problem of disappearing file descriptors
		919
		920	Some backends (e.g kqueue, epoll) need to be told about closing a file
		921	descriptor (either by calling C<close> explicitly or by any other means,
		922	such as C<dup>). The reason is that you register interest in some file
		923	descriptor, but when it goes away, the operating system will silently drop
		924	this interest. If another file descriptor with the same number then is
		925	registered with libev, there is no efficient way to see that this is, in
		926	fact, a different file descriptor.
		927
		928	To avoid having to explicitly tell libev about such cases, libev follows
		929	the following policy: Each time C<ev_io_set> is being called, libev
		930	will assume that this is potentially a new file descriptor, otherwise
		931	it is assumed that the file descriptor stays the same. That means that
		932	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		933	descriptor even if the file descriptor number itself did not change.
		934
		935	This is how one would do it normally anyway, the important point is that
		936	the libev application should not optimise around libev but should leave
		937	optimisations to libev.
		938
		939
		940	=head3 Watcher-Specific Functions
835		941
836	=over 4	942	=over 4
837		943
838	=item ev_io_init (ev_io *, callback, int fd, int events)	944	=item ev_io_init (ev_io *, callback, int fd, int events)
839		945
…		…
893		999
894	The callback is guarenteed to be invoked only when its timeout has passed,	1000	The callback is guarenteed to be invoked only when its timeout has passed,
895	but if multiple timers become ready during the same loop iteration then	1001	but if multiple timers become ready during the same loop iteration then
896	order of execution is undefined.	1002	order of execution is undefined.
897		1003
		1004	=head3 Watcher-Specific Functions and Data Members
		1005
898	=over 4	1006	=over 4
899		1007
900	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1008	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
901		1009
902	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1010	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
915	=item ev_timer_again (loop)	1023	=item ev_timer_again (loop)
916		1024
917	This will act as if the timer timed out and restart it again if it is	1025	This will act as if the timer timed out and restart it again if it is
918	repeating. The exact semantics are:	1026	repeating. The exact semantics are:
919		1027
		1028	If the timer is pending, its pending status is cleared.
		1029
920	If the timer is started but nonrepeating, stop it.	1030	If the timer is started but nonrepeating, stop it (as if it timed out).
921		1031
922	If the timer is repeating, either start it if necessary (with the repeat	1032	If the timer is repeating, either start it if necessary (with the
923	value), or reset the running timer to the repeat value.	1033	C<repeat> value), or reset the running timer to the C<repeat> value.
924		1034
925	This sounds a bit complicated, but here is a useful and typical	1035	This sounds a bit complicated, but here is a useful and typical
926	example: Imagine you have a tcp connection and you want a so-called	1036	example: Imagine you have a tcp connection and you want a so-called idle
927	idle timeout, that is, you want to be called when there have been,	1037	timeout, that is, you want to be called when there have been, say, 60
928	say, 60 seconds of inactivity on the socket. The easiest way to do	1038	seconds of inactivity on the socket. The easiest way to do this is to
929	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling	1039	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
930	C<ev_timer_again> each time you successfully read or write some data. If	1040	C<ev_timer_again> each time you successfully read or write some data. If
931	you go into an idle state where you do not expect data to travel on the	1041	you go into an idle state where you do not expect data to travel on the
932	socket, you can stop the timer, and again will automatically restart it if	1042	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
933	need be.	1043	automatically restart it if need be.
934		1044
935	You can also ignore the C<after> value and C<ev_timer_start> altogether	1045	That means you can ignore the C<after> value and C<ev_timer_start>
936	and only ever use the C<repeat> value:	1046	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
937		1047
938	ev_timer_init (timer, callback, 0., 5.);	1048	ev_timer_init (timer, callback, 0., 5.);
939	ev_timer_again (loop, timer);	1049	ev_timer_again (loop, timer);
940	...	1050	...
941	timer->again = 17.;	1051	timer->again = 17.;
942	ev_timer_again (loop, timer);	1052	ev_timer_again (loop, timer);
943	...	1053	...
944	timer->again = 10.;	1054	timer->again = 10.;
945	ev_timer_again (loop, timer);	1055	ev_timer_again (loop, timer);
946		1056
947	This is more efficient then stopping/starting the timer eahc time you want	1057	This is more slightly efficient then stopping/starting the timer each time
948	to modify its timeout value.	1058	you want to modify its timeout value.
949		1059
950	=item ev_tstamp repeat [read-write]	1060	=item ev_tstamp repeat [read-write]
951		1061
952	The current C<repeat> value. Will be used each time the watcher times out	1062	The current C<repeat> value. Will be used each time the watcher times out
953	or C<ev_timer_again> is called and determines the next timeout (if any),	1063	or C<ev_timer_again> is called and determines the next timeout (if any),
…		…
995	but on wallclock time (absolute time). You can tell a periodic watcher	1105	but on wallclock time (absolute time). You can tell a periodic watcher
996	to trigger "at" some specific point in time. For example, if you tell a	1106	to trigger "at" some specific point in time. For example, if you tell a
997	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1107	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
998	+ 10.>) and then reset your system clock to the last year, then it will	1108	+ 10.>) and then reset your system clock to the last year, then it will
999	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1109	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
1000	roughly 10 seconds later and of course not if you reset your system time	1110	roughly 10 seconds later).
1001	again).
1002		1111
1003	They can also be used to implement vastly more complex timers, such as	1112	They can also be used to implement vastly more complex timers, such as
1004	triggering an event on eahc midnight, local time.	1113	triggering an event on each midnight, local time or other, complicated,
		1114	rules.
1005		1115
1006	As with timers, the callback is guarenteed to be invoked only when the	1116	As with timers, the callback is guarenteed to be invoked only when the
1007	time (C<at>) has been passed, but if multiple periodic timers become ready	1117	time (C<at>) has been passed, but if multiple periodic timers become ready
1008	during the same loop iteration then order of execution is undefined.	1118	during the same loop iteration then order of execution is undefined.
1009		1119
		1120	=head3 Watcher-Specific Functions and Data Members
		1121
1010	=over 4	1122	=over 4
1011		1123
1012	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1124	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
1013		1125
1014	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1126	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
1016	Lots of arguments, lets sort it out... There are basically three modes of	1128	Lots of arguments, lets sort it out... There are basically three modes of
1017	operation, and we will explain them from simplest to complex:	1129	operation, and we will explain them from simplest to complex:
1018		1130
1019	=over 4	1131	=over 4
1020		1132
1021	=item * absolute timer (interval = reschedule_cb = 0)	1133	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1022		1134
1023	In this configuration the watcher triggers an event at the wallclock time	1135	In this configuration the watcher triggers an event at the wallclock time
1024	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1136	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
1025	that is, if it is to be run at January 1st 2011 then it will run when the	1137	that is, if it is to be run at January 1st 2011 then it will run when the
1026	system time reaches or surpasses this time.	1138	system time reaches or surpasses this time.
1027		1139
1028	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1140	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1029		1141
1030	In this mode the watcher will always be scheduled to time out at the next	1142	In this mode the watcher will always be scheduled to time out at the next
1031	C<at + N * interval> time (for some integer N) and then repeat, regardless	1143	C<at + N * interval> time (for some integer N, which can also be negative)
1032	of any time jumps.	1144	and then repeat, regardless of any time jumps.
1033		1145
1034	This can be used to create timers that do not drift with respect to system	1146	This can be used to create timers that do not drift with respect to system
1035	time:	1147	time:
1036		1148
1037	ev_periodic_set (&periodic, 0., 3600., 0);	1149	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1043		1155
1044	Another way to think about it (for the mathematically inclined) is that	1156	Another way to think about it (for the mathematically inclined) is that
1045	C<ev_periodic> will try to run the callback in this mode at the next possible	1157	C<ev_periodic> will try to run the callback in this mode at the next possible
1046	time where C<time = at (mod interval)>, regardless of any time jumps.	1158	time where C<time = at (mod interval)>, regardless of any time jumps.
1047		1159
		1160	For numerical stability it is preferable that the C<at> value is near
		1161	C<ev_now ()> (the current time), but there is no range requirement for
		1162	this value.
		1163
1048	=item * manual reschedule mode (reschedule_cb = callback)	1164	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1049		1165
1050	In this mode the values for C<interval> and C<at> are both being	1166	In this mode the values for C<interval> and C<at> are both being
1051	ignored. Instead, each time the periodic watcher gets scheduled, the	1167	ignored. Instead, each time the periodic watcher gets scheduled, the
1052	reschedule callback will be called with the watcher as first, and the	1168	reschedule callback will be called with the watcher as first, and the
1053	current time as second argument.	1169	current time as second argument.
1054		1170
1055	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1171	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1056	ever, or make any event loop modifications>. If you need to stop it,	1172	ever, or make any event loop modifications>. If you need to stop it,
1057	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1173	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1058	starting a prepare watcher).	1174	starting an C<ev_prepare> watcher, which is legal).
1059		1175
1060	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	1176	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
1061	ev_tstamp now)>, e.g.:	1177	ev_tstamp now)>, e.g.:
1062		1178
1063	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1179	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
1086	Simply stops and restarts the periodic watcher again. This is only useful	1202	Simply stops and restarts the periodic watcher again. This is only useful
1087	when you changed some parameters or the reschedule callback would return	1203	when you changed some parameters or the reschedule callback would return
1088	a different time than the last time it was called (e.g. in a crond like	1204	a different time than the last time it was called (e.g. in a crond like
1089	program when the crontabs have changed).	1205	program when the crontabs have changed).
1090		1206
		1207	=item ev_tstamp offset [read-write]
		1208
		1209	When repeating, this contains the offset value, otherwise this is the
		1210	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1211
		1212	Can be modified any time, but changes only take effect when the periodic
		1213	timer fires or C<ev_periodic_again> is being called.
		1214
1091	=item ev_tstamp interval [read-write]	1215	=item ev_tstamp interval [read-write]
1092		1216
1093	The current interval value. Can be modified any time, but changes only	1217	The current interval value. Can be modified any time, but changes only
1094	take effect when the periodic timer fires or C<ev_periodic_again> is being	1218	take effect when the periodic timer fires or C<ev_periodic_again> is being
1095	called.	1219	called.
…		…
1097	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]	1221	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
1098		1222
1099	The current reschedule callback, or C<0>, if this functionality is	1223	The current reschedule callback, or C<0>, if this functionality is
1100	switched off. Can be changed any time, but changes only take effect when	1224	switched off. Can be changed any time, but changes only take effect when
1101	the periodic timer fires or C<ev_periodic_again> is being called.	1225	the periodic timer fires or C<ev_periodic_again> is being called.
		1226
		1227	=item ev_tstamp at [read-only]
		1228
		1229	When active, contains the absolute time that the watcher is supposed to
		1230	trigger next.
1102		1231
1103	=back	1232	=back
1104		1233
1105	Example: Call a callback every hour, or, more precisely, whenever the	1234	Example: Call a callback every hour, or, more precisely, whenever the
1106	system clock is divisible by 3600. The callback invocation times have	1235	system clock is divisible by 3600. The callback invocation times have
…		…
1148	with the kernel (thus it coexists with your own signal handlers as long	1277	with the kernel (thus it coexists with your own signal handlers as long
1149	as you don't register any with libev). Similarly, when the last signal	1278	as you don't register any with libev). Similarly, when the last signal
1150	watcher for a signal is stopped libev will reset the signal handler to	1279	watcher for a signal is stopped libev will reset the signal handler to
1151	SIG_DFL (regardless of what it was set to before).	1280	SIG_DFL (regardless of what it was set to before).
1152		1281
		1282	=head3 Watcher-Specific Functions and Data Members
		1283
1153	=over 4	1284	=over 4
1154		1285
1155	=item ev_signal_init (ev_signal *, callback, int signum)	1286	=item ev_signal_init (ev_signal *, callback, int signum)
1156		1287
1157	=item ev_signal_set (ev_signal *, int signum)	1288	=item ev_signal_set (ev_signal *, int signum)
…		…
1168		1299
1169	=head2 C<ev_child> - watch out for process status changes	1300	=head2 C<ev_child> - watch out for process status changes
1170		1301
1171	Child watchers trigger when your process receives a SIGCHLD in response to	1302	Child watchers trigger when your process receives a SIGCHLD in response to
1172	some child status changes (most typically when a child of yours dies).	1303	some child status changes (most typically when a child of yours dies).
		1304
		1305	=head3 Watcher-Specific Functions and Data Members
1173		1306
1174	=over 4	1307	=over 4
1175		1308
1176	=item ev_child_init (ev_child *, callback, int pid)	1309	=item ev_child_init (ev_child *, callback, int pid)
1177		1310
…		…
1221	The path does not need to exist: changing from "path exists" to "path does	1354	The path does not need to exist: changing from "path exists" to "path does
1222	not exist" is a status change like any other. The condition "path does	1355	not exist" is a status change like any other. The condition "path does
1223	not exist" is signified by the C<st_nlink> field being zero (which is	1356	not exist" is signified by the C<st_nlink> field being zero (which is
1224	otherwise always forced to be at least one) and all the other fields of	1357	otherwise always forced to be at least one) and all the other fields of
1225	the stat buffer having unspecified contents.	1358	the stat buffer having unspecified contents.
		1359
		1360	The path I<should> be absolute and I<must not> end in a slash. If it is
		1361	relative and your working directory changes, the behaviour is undefined.
1226		1362
1227	Since there is no standard to do this, the portable implementation simply	1363	Since there is no standard to do this, the portable implementation simply
1228	calls C<stat (2)> regularly on the path to see if it changed somehow. You	1364	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1229	can specify a recommended polling interval for this case. If you specify	1365	can specify a recommended polling interval for this case. If you specify
1230	a polling interval of C<0> (highly recommended!) then a I<suitable,	1366	a polling interval of C<0> (highly recommended!) then a I<suitable,
…		…
1242	reader). Inotify will be used to give hints only and should not change the	1378	reader). Inotify will be used to give hints only and should not change the
1243	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1379	semantics of C<ev_stat> watchers, which means that libev sometimes needs
1244	to fall back to regular polling again even with inotify, but changes are	1380	to fall back to regular polling again even with inotify, but changes are
1245	usually detected immediately, and if the file exists there will be no	1381	usually detected immediately, and if the file exists there will be no
1246	polling.	1382	polling.
		1383
		1384	=head3 Watcher-Specific Functions and Data Members
1247		1385
1248	=over 4	1386	=over 4
1249		1387
1250	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1388	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1251		1389
…		…
1315	ev_stat_start (loop, &passwd);	1453	ev_stat_start (loop, &passwd);
1316		1454
1317		1455
1318	=head2 C<ev_idle> - when you've got nothing better to do...	1456	=head2 C<ev_idle> - when you've got nothing better to do...
1319		1457
1320	Idle watchers trigger events when there are no other events are pending	1458	Idle watchers trigger events when no other events of the same or higher
1321	(prepare, check and other idle watchers do not count). That is, as long	1459	priority are pending (prepare, check and other idle watchers do not
1322	as your process is busy handling sockets or timeouts (or even signals,	1460	count).
1323	imagine) it will not be triggered. But when your process is idle all idle	1461
1324	watchers are being called again and again, once per event loop iteration -	1462	That is, as long as your process is busy handling sockets or timeouts
		1463	(or even signals, imagine) of the same or higher priority it will not be
		1464	triggered. But when your process is idle (or only lower-priority watchers
		1465	are pending), the idle watchers are being called once per event loop
1325	until stopped, that is, or your process receives more events and becomes	1466	iteration - until stopped, that is, or your process receives more events
1326	busy.	1467	and becomes busy again with higher priority stuff.
1327		1468
1328	The most noteworthy effect is that as long as any idle watchers are	1469	The most noteworthy effect is that as long as any idle watchers are
1329	active, the process will not block when waiting for new events.	1470	active, the process will not block when waiting for new events.
1330		1471
1331	Apart from keeping your process non-blocking (which is a useful	1472	Apart from keeping your process non-blocking (which is a useful
1332	effect on its own sometimes), idle watchers are a good place to do	1473	effect on its own sometimes), idle watchers are a good place to do
1333	"pseudo-background processing", or delay processing stuff to after the	1474	"pseudo-background processing", or delay processing stuff to after the
1334	event loop has handled all outstanding events.	1475	event loop has handled all outstanding events.
		1476
		1477	=head3 Watcher-Specific Functions and Data Members
1335		1478
1336	=over 4	1479	=over 4
1337		1480
1338	=item ev_idle_init (ev_signal *, callback)	1481	=item ev_idle_init (ev_signal *, callback)
1339		1482
…		…
1397	with priority higher than or equal to the event loop and one coroutine	1540	with priority higher than or equal to the event loop and one coroutine
1398	of lower priority, but only once, using idle watchers to keep the event	1541	of lower priority, but only once, using idle watchers to keep the event
1399	loop from blocking if lower-priority coroutines are active, thus mapping	1542	loop from blocking if lower-priority coroutines are active, thus mapping
1400	low-priority coroutines to idle/background tasks).	1543	low-priority coroutines to idle/background tasks).
1401		1544
		1545	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1546	priority, to ensure that they are being run before any other watchers
		1547	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1548	too) should not activate ("feed") events into libev. While libev fully
		1549	supports this, they will be called before other C<ev_check> watchers did
		1550	their job. As C<ev_check> watchers are often used to embed other event
		1551	loops those other event loops might be in an unusable state until their
		1552	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1553	others).
		1554
		1555	=head3 Watcher-Specific Functions and Data Members
		1556
1402	=over 4	1557	=over 4
1403		1558
1404	=item ev_prepare_init (ev_prepare *, callback)	1559	=item ev_prepare_init (ev_prepare *, callback)
1405		1560
1406	=item ev_check_init (ev_check *, callback)	1561	=item ev_check_init (ev_check *, callback)
…		…
1409	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1564	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1410	macros, but using them is utterly, utterly and completely pointless.	1565	macros, but using them is utterly, utterly and completely pointless.
1411		1566
1412	=back	1567	=back
1413		1568
1414	Example: To include a library such as adns, you would add IO watchers	1569	There are a number of principal ways to embed other event loops or modules
1415	and a timeout watcher in a prepare handler, as required by libadns, and	1570	into libev. Here are some ideas on how to include libadns into libev
		1571	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1572	use for an actually working example. Another Perl module named C<EV::Glib>
		1573	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1574	into the Glib event loop).
		1575
		1576	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1416	in a check watcher, destroy them and call into libadns. What follows is	1577	and in a check watcher, destroy them and call into libadns. What follows
1417	pseudo-code only of course:	1578	is pseudo-code only of course. This requires you to either use a low
		1579	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1580	the callbacks for the IO/timeout watchers might not have been called yet.
1418		1581
1419	static ev_io iow [nfd];	1582	static ev_io iow [nfd];
1420	static ev_timer tw;	1583	static ev_timer tw;
1421		1584
1422	static void	1585	static void
1423	io_cb (ev_loop loop, ev_io w, int revents)	1586	io_cb (ev_loop loop, ev_io w, int revents)
1424	{	1587	{
1425	// set the relevant poll flags
1426	// could also call adns_processreadable etc. here
1427	struct pollfd fd = (struct pollfd )w->data;
1428	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1429	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1430	}	1588	}
1431		1589
1432	// create io watchers for each fd and a timer before blocking	1590	// create io watchers for each fd and a timer before blocking
1433	static void	1591	static void
1434	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1592	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1435	{	1593	{
1436	int timeout = 3600000;truct pollfd fds [nfd];	1594	int timeout = 3600000;
		1595	struct pollfd fds [nfd];
1437	// actual code will need to loop here and realloc etc.	1596	// actual code will need to loop here and realloc etc.
1438	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1597	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1439		1598
1440	/* the callback is illegal, but won't be called as we stop during check */	1599	/* the callback is illegal, but won't be called as we stop during check */
1441	ev_timer_init (&tw, 0, timeout * 1e-3);	1600	ev_timer_init (&tw, 0, timeout * 1e-3);
1442	ev_timer_start (loop, &tw);	1601	ev_timer_start (loop, &tw);
1443		1602
1444	// create on ev_io per pollfd	1603	// create one ev_io per pollfd
1445	for (int i = 0; i < nfd; ++i)	1604	for (int i = 0; i < nfd; ++i)
1446	{	1605	{
1447	ev_io_init (iow + i, io_cb, fds [i].fd,	1606	ev_io_init (iow + i, io_cb, fds [i].fd,
1448	((fds [i].events & POLLIN ? EV_READ : 0)	1607	((fds [i].events & POLLIN ? EV_READ : 0)
1449	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1608	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1450		1609
1451	fds [i].revents = 0;	1610	fds [i].revents = 0;
1452	iow [i].data = fds + i;
1453	ev_io_start (loop, iow + i);	1611	ev_io_start (loop, iow + i);
1454	}	1612	}
1455	}	1613	}
1456		1614
1457	// stop all watchers after blocking	1615	// stop all watchers after blocking
…		…
1459	adns_check_cb (ev_loop loop, ev_check w, int revents)	1617	adns_check_cb (ev_loop loop, ev_check w, int revents)
1460	{	1618	{
1461	ev_timer_stop (loop, &tw);	1619	ev_timer_stop (loop, &tw);
1462		1620
1463	for (int i = 0; i < nfd; ++i)	1621	for (int i = 0; i < nfd; ++i)
		1622	{
		1623	// set the relevant poll flags
		1624	// could also call adns_processreadable etc. here
		1625	struct pollfd *fd = fds + i;
		1626	int revents = ev_clear_pending (iow + i);
		1627	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1628	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1629
		1630	// now stop the watcher
1464	ev_io_stop (loop, iow + i);	1631	ev_io_stop (loop, iow + i);
		1632	}
1465		1633
1466	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1634	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1635	}
		1636
		1637	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1638	in the prepare watcher and would dispose of the check watcher.
		1639
		1640	Method 3: If the module to be embedded supports explicit event
		1641	notification (adns does), you can also make use of the actual watcher
		1642	callbacks, and only destroy/create the watchers in the prepare watcher.
		1643
		1644	static void
		1645	timer_cb (EV_P_ ev_timer *w, int revents)
		1646	{
		1647	adns_state ads = (adns_state)w->data;
		1648	update_now (EV_A);
		1649
		1650	adns_processtimeouts (ads, &tv_now);
		1651	}
		1652
		1653	static void
		1654	io_cb (EV_P_ ev_io *w, int revents)
		1655	{
		1656	adns_state ads = (adns_state)w->data;
		1657	update_now (EV_A);
		1658
		1659	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1660	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1661	}
		1662
		1663	// do not ever call adns_afterpoll
		1664
		1665	Method 4: Do not use a prepare or check watcher because the module you
		1666	want to embed is too inflexible to support it. Instead, youc na override
		1667	their poll function. The drawback with this solution is that the main
		1668	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1669	this.
		1670
		1671	static gint
		1672	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1673	{
		1674	int got_events = 0;
		1675
		1676	for (n = 0; n < nfds; ++n)
		1677	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1678
		1679	if (timeout >= 0)
		1680	// create/start timer
		1681
		1682	// poll
		1683	ev_loop (EV_A_ 0);
		1684
		1685	// stop timer again
		1686	if (timeout >= 0)
		1687	ev_timer_stop (EV_A_ &to);
		1688
		1689	// stop io watchers again - their callbacks should have set
		1690	for (n = 0; n < nfds; ++n)
		1691	ev_io_stop (EV_A_ iow [n]);
		1692
		1693	return got_events;
1467	}	1694	}
1468		1695
1469		1696
1470	=head2 C<ev_embed> - when one backend isn't enough...	1697	=head2 C<ev_embed> - when one backend isn't enough...
1471		1698
…		…
1535	ev_embed_start (loop_hi, &embed);	1762	ev_embed_start (loop_hi, &embed);
1536	}	1763	}
1537	else	1764	else
1538	loop_lo = loop_hi;	1765	loop_lo = loop_hi;
1539		1766
		1767	=head3 Watcher-Specific Functions and Data Members
		1768
1540	=over 4	1769	=over 4
1541		1770
1542	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)	1771	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)
1543		1772
1544	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)	1773	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)
…		…
1570	event loop blocks next and before C<ev_check> watchers are being called,	1799	event loop blocks next and before C<ev_check> watchers are being called,
1571	and only in the child after the fork. If whoever good citizen calling	1800	and only in the child after the fork. If whoever good citizen calling
1572	C<ev_default_fork> cheats and calls it in the wrong process, the fork	1801	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1573	handlers will be invoked, too, of course.	1802	handlers will be invoked, too, of course.
1574		1803
		1804	=head3 Watcher-Specific Functions and Data Members
		1805
1575	=over 4	1806	=over 4
1576		1807
1577	=item ev_fork_init (ev_signal *, callback)	1808	=item ev_fork_init (ev_signal *, callback)
1578		1809
1579	Initialises and configures the fork watcher - it has no parameters of any	1810	Initialises and configures the fork watcher - it has no parameters of any
…		…
1675		1906
1676	To use it,	1907	To use it,
1677		1908
1678	#include <ev++.h>	1909	#include <ev++.h>
1679		1910
1680	(it is not installed by default). This automatically includes F<ev.h>	1911	This automatically includes F<ev.h> and puts all of its definitions (many
1681	and puts all of its definitions (many of them macros) into the global	1912	of them macros) into the global namespace. All C++ specific things are
1682	namespace. All C++ specific things are put into the C<ev> namespace.	1913	put into the C<ev> namespace. It should support all the same embedding
		1914	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1683		1915
1684	It should support all the same embedding options as F<ev.h>, most notably	1916	Care has been taken to keep the overhead low. The only data member the C++
1685	C<EV_MULTIPLICITY>.	1917	classes add (compared to plain C-style watchers) is the event loop pointer
		1918	that the watcher is associated with (or no additional members at all if
		1919	you disable C<EV_MULTIPLICITY> when embedding libev).
		1920
		1921	Currently, functions, and static and non-static member functions can be
		1922	used as callbacks. Other types should be easy to add as long as they only
		1923	need one additional pointer for context. If you need support for other
		1924	types of functors please contact the author (preferably after implementing
		1925	it).
1686		1926
1687	Here is a list of things available in the C<ev> namespace:	1927	Here is a list of things available in the C<ev> namespace:
1688		1928
1689	=over 4	1929	=over 4
1690		1930
…		…
1706		1946
1707	All of those classes have these methods:	1947	All of those classes have these methods:
1708		1948
1709	=over 4	1949	=over 4
1710		1950
1711	=item ev::TYPE::TYPE (object , object::method )	1951	=item ev::TYPE::TYPE ()
1712		1952
1713	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1953	=item ev::TYPE::TYPE (struct ev_loop *)
1714		1954
1715	=item ev::TYPE::~TYPE	1955	=item ev::TYPE::~TYPE
1716		1956
1717	The constructor takes a pointer to an object and a method pointer to	1957	The constructor (optionally) takes an event loop to associate the watcher
1718	the event handler callback to call in this class. The constructor calls	1958	with. If it is omitted, it will use C<EV_DEFAULT>.
1719	C<ev_init> for you, which means you have to call the C<set> method	1959
1720	before starting it. If you do not specify a loop then the constructor	1960	The constructor calls C<ev_init> for you, which means you have to call the
1721	automatically associates the default loop with this watcher.	1961	C<set> method before starting it.
		1962
		1963	It will not set a callback, however: You have to call the templated C<set>
		1964	method to set a callback before you can start the watcher.
		1965
		1966	(The reason why you have to use a method is a limitation in C++ which does
		1967	not allow explicit template arguments for constructors).
1722		1968
1723	The destructor automatically stops the watcher if it is active.	1969	The destructor automatically stops the watcher if it is active.
		1970
		1971	=item w->set<class, &class::method> (object *)
		1972
		1973	This method sets the callback method to call. The method has to have a
		1974	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1975	first argument and the C<revents> as second. The object must be given as
		1976	parameter and is stored in the C<data> member of the watcher.
		1977
		1978	This method synthesizes efficient thunking code to call your method from
		1979	the C callback that libev requires. If your compiler can inline your
		1980	callback (i.e. it is visible to it at the place of the C<set> call and
		1981	your compiler is good :), then the method will be fully inlined into the
		1982	thunking function, making it as fast as a direct C callback.
		1983
		1984	Example: simple class declaration and watcher initialisation
		1985
		1986	struct myclass
		1987	{
		1988	void io_cb (ev::io &w, int revents) { }
		1989	}
		1990
		1991	myclass obj;
		1992	ev::io iow;
		1993	iow.set <myclass, &myclass::io_cb> (&obj);
		1994
		1995	=item w->set<function> (void *data = 0)
		1996
		1997	Also sets a callback, but uses a static method or plain function as
		1998	callback. The optional C<data> argument will be stored in the watcher's
		1999	C<data> member and is free for you to use.
		2000
		2001	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2002
		2003	See the method-C<set> above for more details.
		2004
		2005	Example:
		2006
		2007	static void io_cb (ev::io &w, int revents) { }
		2008	iow.set <io_cb> ();
1724		2009
1725	=item w->set (struct ev_loop *)	2010	=item w->set (struct ev_loop *)
1726		2011
1727	Associates a different C<struct ev_loop> with this watcher. You can only	2012	Associates a different C<struct ev_loop> with this watcher. You can only
1728	do this when the watcher is inactive (and not pending either).	2013	do this when the watcher is inactive (and not pending either).
1729		2014
1730	=item w->set ([args])	2015	=item w->set ([args])
1731		2016
1732	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2017	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1733	called at least once. Unlike the C counterpart, an active watcher gets	2018	called at least once. Unlike the C counterpart, an active watcher gets
1734	automatically stopped and restarted.	2019	automatically stopped and restarted when reconfiguring it with this
		2020	method.
1735		2021
1736	=item w->start ()	2022	=item w->start ()
1737		2023
1738	Starts the watcher. Note that there is no C<loop> argument as the	2024	Starts the watcher. Note that there is no C<loop> argument, as the
1739	constructor already takes the loop.	2025	constructor already stores the event loop.
1740		2026
1741	=item w->stop ()	2027	=item w->stop ()
1742		2028
1743	Stops the watcher if it is active. Again, no C<loop> argument.	2029	Stops the watcher if it is active. Again, no C<loop> argument.
1744		2030
1745	=item w->again () C<ev::timer>, C<ev::periodic> only	2031	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1746		2032
1747	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2033	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1748	C<ev_TYPE_again> function.	2034	C<ev_TYPE_again> function.
1749		2035
1750	=item w->sweep () C<ev::embed> only	2036	=item w->sweep () (C<ev::embed> only)
1751		2037
1752	Invokes C<ev_embed_sweep>.	2038	Invokes C<ev_embed_sweep>.
1753		2039
1754	=item w->update () C<ev::stat> only	2040	=item w->update () (C<ev::stat> only)
1755		2041
1756	Invokes C<ev_stat_stat>.	2042	Invokes C<ev_stat_stat>.
1757		2043
1758	=back	2044	=back
1759		2045
…		…
1769		2055
1770	myclass ();	2056	myclass ();
1771	}	2057	}
1772		2058
1773	myclass::myclass (int fd)	2059	myclass::myclass (int fd)
1774	: io (this, &myclass::io_cb),
1775	idle (this, &myclass::idle_cb)
1776	{	2060	{
		2061	io .set <myclass, &myclass::io_cb > (this);
		2062	idle.set <myclass, &myclass::idle_cb> (this);
		2063
1777	io.start (fd, ev::READ);	2064	io.start (fd, ev::READ);
1778	}	2065	}
1779		2066
1780		2067
1781	=head1 MACRO MAGIC	2068	=head1 MACRO MAGIC
1782		2069
1783	Libev can be compiled with a variety of options, the most fundemantal is	2070	Libev can be compiled with a variety of options, the most fundamantal
1784	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2071	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1785	callbacks have an initial C<struct ev_loop *> argument.	2072	functions and callbacks have an initial C<struct ev_loop *> argument.
1786		2073
1787	To make it easier to write programs that cope with either variant, the	2074	To make it easier to write programs that cope with either variant, the
1788	following macros are defined:	2075	following macros are defined:
1789		2076
1790	=over 4	2077	=over 4
…		…
1822	Similar to the other two macros, this gives you the value of the default	2109	Similar to the other two macros, this gives you the value of the default
1823	loop, if multiple loops are supported ("ev loop default").	2110	loop, if multiple loops are supported ("ev loop default").
1824		2111
1825	=back	2112	=back
1826		2113
1827	Example: Declare and initialise a check watcher, working regardless of	2114	Example: Declare and initialise a check watcher, utilising the above
1828	wether multiple loops are supported or not.	2115	macros so it will work regardless of whether multiple loops are supported
		2116	or not.
1829		2117
1830	static void	2118	static void
1831	check_cb (EV_P_ ev_timer *w, int revents)	2119	check_cb (EV_P_ ev_timer *w, int revents)
1832	{	2120	{
1833	ev_check_stop (EV_A_ w);	2121	ev_check_stop (EV_A_ w);
…		…
1835		2123
1836	ev_check check;	2124	ev_check check;
1837	ev_check_init (&check, check_cb);	2125	ev_check_init (&check, check_cb);
1838	ev_check_start (EV_DEFAULT_ &check);	2126	ev_check_start (EV_DEFAULT_ &check);
1839	ev_loop (EV_DEFAULT_ 0);	2127	ev_loop (EV_DEFAULT_ 0);
1840
1841		2128
1842	=head1 EMBEDDING	2129	=head1 EMBEDDING
1843		2130
1844	Libev can (and often is) directly embedded into host	2131	Libev can (and often is) directly embedded into host
1845	applications. Examples of applications that embed it include the Deliantra	2132	applications. Examples of applications that embed it include the Deliantra
…		…
1885	ev_vars.h	2172	ev_vars.h
1886	ev_wrap.h	2173	ev_wrap.h
1887		2174
1888	ev_win32.c required on win32 platforms only	2175	ev_win32.c required on win32 platforms only
1889		2176
1890	ev_select.c only when select backend is enabled (which is by default)	2177	ev_select.c only when select backend is enabled (which is enabled by default)
1891	ev_poll.c only when poll backend is enabled (disabled by default)	2178	ev_poll.c only when poll backend is enabled (disabled by default)
1892	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2179	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1893	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2180	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1894	ev_port.c only when the solaris port backend is enabled (disabled by default)	2181	ev_port.c only when the solaris port backend is enabled (disabled by default)
1895		2182
…		…
2058	will have the C<struct ev_loop *> as first argument, and you can create	2345	will have the C<struct ev_loop *> as first argument, and you can create
2059	additional independent event loops. Otherwise there will be no support	2346	additional independent event loops. Otherwise there will be no support
2060	for multiple event loops and there is no first event loop pointer	2347	for multiple event loops and there is no first event loop pointer
2061	argument. Instead, all functions act on the single default loop.	2348	argument. Instead, all functions act on the single default loop.
2062		2349
		2350	=item EV_MINPRI
		2351
		2352	=item EV_MAXPRI
		2353
		2354	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2355	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2356	provide for more priorities by overriding those symbols (usually defined
		2357	to be C<-2> and C<2>, respectively).
		2358
		2359	When doing priority-based operations, libev usually has to linearly search
		2360	all the priorities, so having many of them (hundreds) uses a lot of space
		2361	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2362	fine.
		2363
		2364	If your embedding app does not need any priorities, defining these both to
		2365	C<0> will save some memory and cpu.
		2366
2063	=item EV_PERIODIC_ENABLE	2367	=item EV_PERIODIC_ENABLE
2064		2368
2065	If undefined or defined to be C<1>, then periodic timers are supported. If	2369	If undefined or defined to be C<1>, then periodic timers are supported. If
		2370	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2371	code.
		2372
		2373	=item EV_IDLE_ENABLE
		2374
		2375	If undefined or defined to be C<1>, then idle watchers are supported. If
2066	defined to be C<0>, then they are not. Disabling them saves a few kB of	2376	defined to be C<0>, then they are not. Disabling them saves a few kB of
2067	code.	2377	code.
2068		2378
2069	=item EV_EMBED_ENABLE	2379	=item EV_EMBED_ENABLE
2070		2380
…		…
2137	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2447	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2138	will be compiled. It is pretty complex because it provides its own header	2448	will be compiled. It is pretty complex because it provides its own header
2139	file.	2449	file.
2140		2450
2141	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2451	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2142	that everybody includes and which overrides some autoconf choices:	2452	that everybody includes and which overrides some configure choices:
2143		2453
		2454	#define EV_MINIMAL 1
2144	#define EV_USE_POLL 0	2455	#define EV_USE_POLL 0
2145	#define EV_MULTIPLICITY 0	2456	#define EV_MULTIPLICITY 0
2146	#define EV_PERIODICS 0	2457	#define EV_PERIODIC_ENABLE 0
		2458	#define EV_STAT_ENABLE 0
		2459	#define EV_FORK_ENABLE 0
2147	#define EV_CONFIG_H <config.h>	2460	#define EV_CONFIG_H <config.h>
		2461	#define EV_MINPRI 0
		2462	#define EV_MAXPRI 0
2148		2463
2149	#include "ev++.h"	2464	#include "ev++.h"
2150		2465
2151	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2466	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2152		2467
…		…
2158		2473
2159	In this section the complexities of (many of) the algorithms used inside	2474	In this section the complexities of (many of) the algorithms used inside
2160	libev will be explained. For complexity discussions about backends see the	2475	libev will be explained. For complexity discussions about backends see the
2161	documentation for C<ev_default_init>.	2476	documentation for C<ev_default_init>.
2162		2477
		2478	All of the following are about amortised time: If an array needs to be
		2479	extended, libev needs to realloc and move the whole array, but this
		2480	happens asymptotically never with higher number of elements, so O(1) might
		2481	mean it might do a lengthy realloc operation in rare cases, but on average
		2482	it is much faster and asymptotically approaches constant time.
		2483
2163	=over 4	2484	=over 4
2164		2485
2165	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2486	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2166		2487
		2488	This means that, when you have a watcher that triggers in one hour and
		2489	there are 100 watchers that would trigger before that then inserting will
		2490	have to skip those 100 watchers.
		2491
2167	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2492	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2168		2493
		2494	That means that for changing a timer costs less than removing/adding them
		2495	as only the relative motion in the event queue has to be paid for.
		2496
2169	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2497	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2170		2498
		2499	These just add the watcher into an array or at the head of a list.
2171	=item Stopping check/prepare/idle watchers: O(1)	2500	=item Stopping check/prepare/idle watchers: O(1)
2172		2501
2173	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2502	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2174		2503
		2504	These watchers are stored in lists then need to be walked to find the
		2505	correct watcher to remove. The lists are usually short (you don't usually
		2506	have many watchers waiting for the same fd or signal).
		2507
2175	=item Finding the next timer per loop iteration: O(1)	2508	=item Finding the next timer per loop iteration: O(1)
2176		2509
2177	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2510	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2178		2511
		2512	A change means an I/O watcher gets started or stopped, which requires
		2513	libev to recalculate its status (and possibly tell the kernel).
		2514
2179	=item Activating one watcher: O(1)	2515	=item Activating one watcher: O(1)
2180		2516
		2517	=item Priority handling: O(number_of_priorities)
		2518
		2519	Priorities are implemented by allocating some space for each
		2520	priority. When doing priority-based operations, libev usually has to
		2521	linearly search all the priorities.
		2522
2181	=back	2523	=back
2182		2524
2183		2525
2184	=head1 AUTHOR	2526	=head1 AUTHOR
2185		2527

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Comparing libev/ev.pod (file contents): Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC vs. Revision 1.86 by root, Tue Dec 18 01:20:33 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC vs.
Revision 1.86 by root, Tue Dec 18 01:20:33 2007 UTC