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

Comparing libev/ev.pod (file contents):
Revision 1.59 by root, Wed Nov 28 17:32:24 2007 UTC vs.
Revision 1.83 by root, Wed Dec 12 17:55:31 2007 UTC

…		…
47		47
48	return 0;	48	return 0;
49	}	49	}
50		50
51	=head1 DESCRIPTION	51	=head1 DESCRIPTION
		52
		53	The newest version of this document is also available as a html-formatted
		54	web page you might find easier to navigate when reading it for the first
		55	time: L<http://cvs.schmorp.de/libev/ev.html>.
52		56
53	Libev is an event loop: you register interest in certain events (such as a	57	Libev is an event loop: you register interest in certain events (such as a
54	file descriptor being readable or a timeout occuring), and it will manage	58	file descriptor being readable or a timeout occuring), and it will manage
55	these event sources and provide your program with events.	59	these event sources and provide your program with events.
56		60
…		…
113		117
114	=item int ev_version_major ()	118	=item int ev_version_major ()
115		119
116	=item int ev_version_minor ()	120	=item int ev_version_minor ()
117		121
118	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
119	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
120	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
121	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
122	version of the library your program was compiled against.	126	version of the library your program was compiled against.
123		127
		128	These version numbers refer to the ABI version of the library, not the
		129	release version.
		130
124	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,
125	as this indicates an incompatible change. Minor versions are usually	132	as this indicates an incompatible change. Minor versions are usually
126	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
127	not a problem.	134	not a problem.
128		135
129	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
130	version.	137	version.
…		…
266	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	273	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
267	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
268	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
269	around bugs.	276	around bugs.
270		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
271	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	298	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
272		299
273	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
274	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,
275	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
…		…
410		437
411	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
412	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
413	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.
414		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
415	=item unsigned int ev_backend (loop)	452	=item unsigned int ev_backend (loop)
416		453
417	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
418	use.	455	use.
419		456
…		…
452	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
453	usually a better approach for this kind of thing.	490	usually a better approach for this kind of thing.
454		491
455	Here are the gory details of what C<ev_loop> does:	492	Here are the gory details of what C<ev_loop> does:
456		493
		494	- Before the first iteration, call any pending watchers.
457	* If there are no active watchers (reference count is zero), return.	495	* If there are no active watchers (reference count is zero), return.
458	- Queue prepare watchers and then call all outstanding watchers.	496	- Queue all prepare watchers and then call all outstanding watchers.
459	- If we have been forked, recreate the kernel state.	497	- If we have been forked, recreate the kernel state.
460	- Update the kernel state with all outstanding changes.	498	- Update the kernel state with all outstanding changes.
461	- Update the "event loop time".	499	- Update the "event loop time".
462	- Calculate for how long to block.	500	- Calculate for how long to block.
463	- Block the process, waiting for any events.	501	- Block the process, waiting for any events.
…		…
702	=item bool ev_is_pending (ev_TYPE *watcher)	740	=item bool ev_is_pending (ev_TYPE *watcher)
703		741
704	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
705	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
706	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
707	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
708	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).
709		748
710	=item callback ev_cb (ev_TYPE *watcher)	749	=item callback ev_cb (ev_TYPE *watcher)
711		750
712	Returns the callback currently set on the watcher.	751	Returns the callback currently set on the watcher.
713		752
714	=item ev_cb_set (ev_TYPE *watcher, callback)	753	=item ev_cb_set (ev_TYPE *watcher, callback)
715		754
716	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
717	(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>.
718		797
719	=back	798	=back
720		799
721		800
722	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	801	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
828	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
829	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.
830		909
831	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
832	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
833	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
834	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
835	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
836		939
837	=over 4	940	=over 4
838		941
839	=item ev_io_init (ev_io *, callback, int fd, int events)	942	=item ev_io_init (ev_io *, callback, int fd, int events)
840		943
…		…
894		997
895	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,
896	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
897	order of execution is undefined.	1000	order of execution is undefined.
898		1001
		1002	=head3 Watcher-Specific Functions and Data Members
		1003
899	=over 4	1004	=over 4
900		1005
901	=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)
902		1007
903	=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)
…		…
916	=item ev_timer_again (loop)	1021	=item ev_timer_again (loop)
917		1022
918	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
919	repeating. The exact semantics are:	1024	repeating. The exact semantics are:
920		1025
		1026	If the timer is pending, its pending status is cleared.
		1027
921	If the timer is started but nonrepeating, stop it.	1028	If the timer is started but nonrepeating, stop it (as if it timed out).
922		1029
923	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
924	value), or reset the running timer to the repeat value.	1031	C<repeat> value), or reset the running timer to the C<repeat> value.
925		1032
926	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
927	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
928	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
929	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
930	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
931	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
932	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
933	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
934	need be.	1041	automatically restart it if need be.
935		1042
936	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>
937	and only ever use the C<repeat> value:	1044	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
938		1045
939	ev_timer_init (timer, callback, 0., 5.);	1046	ev_timer_init (timer, callback, 0., 5.);
940	ev_timer_again (loop, timer);	1047	ev_timer_again (loop, timer);
941	...	1048	...
942	timer->again = 17.;	1049	timer->again = 17.;
943	ev_timer_again (loop, timer);	1050	ev_timer_again (loop, timer);
944	...	1051	...
945	timer->again = 10.;	1052	timer->again = 10.;
946	ev_timer_again (loop, timer);	1053	ev_timer_again (loop, timer);
947		1054
948	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
949	to modify its timeout value.	1056	you want to modify its timeout value.
950		1057
951	=item ev_tstamp repeat [read-write]	1058	=item ev_tstamp repeat [read-write]
952		1059
953	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
954	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),
…		…
996	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
997	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
998	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 ()
999	+ 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
1000	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
1001	roughly 10 seconds later and of course not if you reset your system time	1108	roughly 10 seconds later).
1002	again).
1003		1109
1004	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
1005	triggering an event on eahc midnight, local time.	1111	triggering an event on each midnight, local time or other, complicated,
		1112	rules.
1006		1113
1007	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
1008	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
1009	during the same loop iteration then order of execution is undefined.	1116	during the same loop iteration then order of execution is undefined.
1010		1117
		1118	=head3 Watcher-Specific Functions and Data Members
		1119
1011	=over 4	1120	=over 4
1012		1121
1013	=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)
1014		1123
1015	=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)
…		…
1017	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
1018	operation, and we will explain them from simplest to complex:	1127	operation, and we will explain them from simplest to complex:
1019		1128
1020	=over 4	1129	=over 4
1021		1130
1022	=item * absolute timer (interval = reschedule_cb = 0)	1131	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1023		1132
1024	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
1025	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,
1026	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
1027	system time reaches or surpasses this time.	1136	system time reaches or surpasses this time.
1028		1137
1029	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1138	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1030		1139
1031	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
1032	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)
1033	of any time jumps.	1142	and then repeat, regardless of any time jumps.
1034		1143
1035	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
1036	time:	1145	time:
1037		1146
1038	ev_periodic_set (&periodic, 0., 3600., 0);	1147	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1044		1153
1045	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
1046	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
1047	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.
1048		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
1049	=item * manual reschedule mode (reschedule_cb = callback)	1162	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1050		1163
1051	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
1052	ignored. Instead, each time the periodic watcher gets scheduled, the	1165	ignored. Instead, each time the periodic watcher gets scheduled, the
1053	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
1054	current time as second argument.	1167	current time as second argument.
1055		1168
1056	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,
1057	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,
1058	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
1059	starting a prepare watcher).	1172	starting an C<ev_prepare> watcher, which is legal).
1060		1173
1061	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,
1062	ev_tstamp now)>, e.g.:	1175	ev_tstamp now)>, e.g.:
1063		1176
1064	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)
…		…
1086		1199
1087	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
1088	when you changed some parameters or the reschedule callback would return	1201	when you changed some parameters or the reschedule callback would return
1089	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
1090	program when the crontabs have changed).	1203	program when the crontabs have changed).
		1204
		1205	=item ev_tstamp offset [read-write]
		1206
		1207	When repeating, this contains the offset value, otherwise this is the
		1208	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1209
		1210	Can be modified any time, but changes only take effect when the periodic
		1211	timer fires or C<ev_periodic_again> is being called.
1091		1212
1092	=item ev_tstamp interval [read-write]	1213	=item ev_tstamp interval [read-write]
1093		1214
1094	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
1095	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
…		…
1149	with the kernel (thus it coexists with your own signal handlers as long	1270	with the kernel (thus it coexists with your own signal handlers as long
1150	as you don't register any with libev). Similarly, when the last signal	1271	as you don't register any with libev). Similarly, when the last signal
1151	watcher for a signal is stopped libev will reset the signal handler to	1272	watcher for a signal is stopped libev will reset the signal handler to
1152	SIG_DFL (regardless of what it was set to before).	1273	SIG_DFL (regardless of what it was set to before).
1153		1274
		1275	=head3 Watcher-Specific Functions and Data Members
		1276
1154	=over 4	1277	=over 4
1155		1278
1156	=item ev_signal_init (ev_signal *, callback, int signum)	1279	=item ev_signal_init (ev_signal *, callback, int signum)
1157		1280
1158	=item ev_signal_set (ev_signal *, int signum)	1281	=item ev_signal_set (ev_signal *, int signum)
…		…
1169		1292
1170	=head2 C<ev_child> - watch out for process status changes	1293	=head2 C<ev_child> - watch out for process status changes
1171		1294
1172	Child watchers trigger when your process receives a SIGCHLD in response to	1295	Child watchers trigger when your process receives a SIGCHLD in response to
1173	some child status changes (most typically when a child of yours dies).	1296	some child status changes (most typically when a child of yours dies).
		1297
		1298	=head3 Watcher-Specific Functions and Data Members
1174		1299
1175	=over 4	1300	=over 4
1176		1301
1177	=item ev_child_init (ev_child *, callback, int pid)	1302	=item ev_child_init (ev_child *, callback, int pid)
1178		1303
…		…
1222	The path does not need to exist: changing from "path exists" to "path does	1347	The path does not need to exist: changing from "path exists" to "path does
1223	not exist" is a status change like any other. The condition "path does	1348	not exist" is a status change like any other. The condition "path does
1224	not exist" is signified by the C<st_nlink> field being zero (which is	1349	not exist" is signified by the C<st_nlink> field being zero (which is
1225	otherwise always forced to be at least one) and all the other fields of	1350	otherwise always forced to be at least one) and all the other fields of
1226	the stat buffer having unspecified contents.	1351	the stat buffer having unspecified contents.
		1352
		1353	The path I<should> be absolute and I<must not> end in a slash. If it is
		1354	relative and your working directory changes, the behaviour is undefined.
1227		1355
1228	Since there is no standard to do this, the portable implementation simply	1356	Since there is no standard to do this, the portable implementation simply
1229	calls C<stat (2)> regularly on the path to see if it changed somehow. You	1357	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1230	can specify a recommended polling interval for this case. If you specify	1358	can specify a recommended polling interval for this case. If you specify
1231	a polling interval of C<0> (highly recommended!) then a I<suitable,	1359	a polling interval of C<0> (highly recommended!) then a I<suitable,
…		…
1243	reader). Inotify will be used to give hints only and should not change the	1371	reader). Inotify will be used to give hints only and should not change the
1244	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1372	semantics of C<ev_stat> watchers, which means that libev sometimes needs
1245	to fall back to regular polling again even with inotify, but changes are	1373	to fall back to regular polling again even with inotify, but changes are
1246	usually detected immediately, and if the file exists there will be no	1374	usually detected immediately, and if the file exists there will be no
1247	polling.	1375	polling.
		1376
		1377	=head3 Watcher-Specific Functions and Data Members
1248		1378
1249	=over 4	1379	=over 4
1250		1380
1251	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1381	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1252		1382
…		…
1316	ev_stat_start (loop, &passwd);	1446	ev_stat_start (loop, &passwd);
1317		1447
1318		1448
1319	=head2 C<ev_idle> - when you've got nothing better to do...	1449	=head2 C<ev_idle> - when you've got nothing better to do...
1320		1450
1321	Idle watchers trigger events when there are no other events are pending	1451	Idle watchers trigger events when no other events of the same or higher
1322	(prepare, check and other idle watchers do not count). That is, as long	1452	priority are pending (prepare, check and other idle watchers do not
1323	as your process is busy handling sockets or timeouts (or even signals,	1453	count).
1324	imagine) it will not be triggered. But when your process is idle all idle	1454
1325	watchers are being called again and again, once per event loop iteration -	1455	That is, as long as your process is busy handling sockets or timeouts
		1456	(or even signals, imagine) of the same or higher priority it will not be
		1457	triggered. But when your process is idle (or only lower-priority watchers
		1458	are pending), the idle watchers are being called once per event loop
1326	until stopped, that is, or your process receives more events and becomes	1459	iteration - until stopped, that is, or your process receives more events
1327	busy.	1460	and becomes busy again with higher priority stuff.
1328		1461
1329	The most noteworthy effect is that as long as any idle watchers are	1462	The most noteworthy effect is that as long as any idle watchers are
1330	active, the process will not block when waiting for new events.	1463	active, the process will not block when waiting for new events.
1331		1464
1332	Apart from keeping your process non-blocking (which is a useful	1465	Apart from keeping your process non-blocking (which is a useful
1333	effect on its own sometimes), idle watchers are a good place to do	1466	effect on its own sometimes), idle watchers are a good place to do
1334	"pseudo-background processing", or delay processing stuff to after the	1467	"pseudo-background processing", or delay processing stuff to after the
1335	event loop has handled all outstanding events.	1468	event loop has handled all outstanding events.
		1469
		1470	=head3 Watcher-Specific Functions and Data Members
1336		1471
1337	=over 4	1472	=over 4
1338		1473
1339	=item ev_idle_init (ev_signal *, callback)	1474	=item ev_idle_init (ev_signal *, callback)
1340		1475
…		…
1398	with priority higher than or equal to the event loop and one coroutine	1533	with priority higher than or equal to the event loop and one coroutine
1399	of lower priority, but only once, using idle watchers to keep the event	1534	of lower priority, but only once, using idle watchers to keep the event
1400	loop from blocking if lower-priority coroutines are active, thus mapping	1535	loop from blocking if lower-priority coroutines are active, thus mapping
1401	low-priority coroutines to idle/background tasks).	1536	low-priority coroutines to idle/background tasks).
1402		1537
		1538	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1539	priority, to ensure that they are being run before any other watchers
		1540	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1541	too) should not activate ("feed") events into libev. While libev fully
		1542	supports this, they will be called before other C<ev_check> watchers did
		1543	their job. As C<ev_check> watchers are often used to embed other event
		1544	loops those other event loops might be in an unusable state until their
		1545	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1546	others).
		1547
		1548	=head3 Watcher-Specific Functions and Data Members
		1549
1403	=over 4	1550	=over 4
1404		1551
1405	=item ev_prepare_init (ev_prepare *, callback)	1552	=item ev_prepare_init (ev_prepare *, callback)
1406		1553
1407	=item ev_check_init (ev_check *, callback)	1554	=item ev_check_init (ev_check *, callback)
…		…
1410	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1557	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1411	macros, but using them is utterly, utterly and completely pointless.	1558	macros, but using them is utterly, utterly and completely pointless.
1412		1559
1413	=back	1560	=back
1414		1561
1415	Example: To include a library such as adns, you would add IO watchers	1562	There are a number of principal ways to embed other event loops or modules
1416	and a timeout watcher in a prepare handler, as required by libadns, and	1563	into libev. Here are some ideas on how to include libadns into libev
		1564	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1565	use for an actually working example. Another Perl module named C<EV::Glib>
		1566	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1567	into the Glib event loop).
		1568
		1569	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1417	in a check watcher, destroy them and call into libadns. What follows is	1570	and in a check watcher, destroy them and call into libadns. What follows
1418	pseudo-code only of course:	1571	is pseudo-code only of course. This requires you to either use a low
		1572	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1573	the callbacks for the IO/timeout watchers might not have been called yet.
1419		1574
1420	static ev_io iow [nfd];	1575	static ev_io iow [nfd];
1421	static ev_timer tw;	1576	static ev_timer tw;
1422		1577
1423	static void	1578	static void
1424	io_cb (ev_loop loop, ev_io w, int revents)	1579	io_cb (ev_loop loop, ev_io w, int revents)
1425	{	1580	{
1426	// set the relevant poll flags
1427	// could also call adns_processreadable etc. here
1428	struct pollfd fd = (struct pollfd )w->data;
1429	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1430	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1431	}	1581	}
1432		1582
1433	// create io watchers for each fd and a timer before blocking	1583	// create io watchers for each fd and a timer before blocking
1434	static void	1584	static void
1435	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1585	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1436	{	1586	{
1437	int timeout = 3600000;truct pollfd fds [nfd];	1587	int timeout = 3600000;
		1588	struct pollfd fds [nfd];
1438	// actual code will need to loop here and realloc etc.	1589	// actual code will need to loop here and realloc etc.
1439	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1590	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1440		1591
1441	/* the callback is illegal, but won't be called as we stop during check */	1592	/* the callback is illegal, but won't be called as we stop during check */
1442	ev_timer_init (&tw, 0, timeout * 1e-3);	1593	ev_timer_init (&tw, 0, timeout * 1e-3);
1443	ev_timer_start (loop, &tw);	1594	ev_timer_start (loop, &tw);
1444		1595
1445	// create on ev_io per pollfd	1596	// create one ev_io per pollfd
1446	for (int i = 0; i < nfd; ++i)	1597	for (int i = 0; i < nfd; ++i)
1447	{	1598	{
1448	ev_io_init (iow + i, io_cb, fds [i].fd,	1599	ev_io_init (iow + i, io_cb, fds [i].fd,
1449	((fds [i].events & POLLIN ? EV_READ : 0)	1600	((fds [i].events & POLLIN ? EV_READ : 0)
1450	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1601	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1451		1602
1452	fds [i].revents = 0;	1603	fds [i].revents = 0;
1453	iow [i].data = fds + i;
1454	ev_io_start (loop, iow + i);	1604	ev_io_start (loop, iow + i);
1455	}	1605	}
1456	}	1606	}
1457		1607
1458	// stop all watchers after blocking	1608	// stop all watchers after blocking
…		…
1460	adns_check_cb (ev_loop loop, ev_check w, int revents)	1610	adns_check_cb (ev_loop loop, ev_check w, int revents)
1461	{	1611	{
1462	ev_timer_stop (loop, &tw);	1612	ev_timer_stop (loop, &tw);
1463		1613
1464	for (int i = 0; i < nfd; ++i)	1614	for (int i = 0; i < nfd; ++i)
		1615	{
		1616	// set the relevant poll flags
		1617	// could also call adns_processreadable etc. here
		1618	struct pollfd *fd = fds + i;
		1619	int revents = ev_clear_pending (iow + i);
		1620	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1621	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1622
		1623	// now stop the watcher
1465	ev_io_stop (loop, iow + i);	1624	ev_io_stop (loop, iow + i);
		1625	}
1466		1626
1467	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1627	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1628	}
		1629
		1630	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1631	in the prepare watcher and would dispose of the check watcher.
		1632
		1633	Method 3: If the module to be embedded supports explicit event
		1634	notification (adns does), you can also make use of the actual watcher
		1635	callbacks, and only destroy/create the watchers in the prepare watcher.
		1636
		1637	static void
		1638	timer_cb (EV_P_ ev_timer *w, int revents)
		1639	{
		1640	adns_state ads = (adns_state)w->data;
		1641	update_now (EV_A);
		1642
		1643	adns_processtimeouts (ads, &tv_now);
		1644	}
		1645
		1646	static void
		1647	io_cb (EV_P_ ev_io *w, int revents)
		1648	{
		1649	adns_state ads = (adns_state)w->data;
		1650	update_now (EV_A);
		1651
		1652	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1653	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1654	}
		1655
		1656	// do not ever call adns_afterpoll
		1657
		1658	Method 4: Do not use a prepare or check watcher because the module you
		1659	want to embed is too inflexible to support it. Instead, youc na override
		1660	their poll function. The drawback with this solution is that the main
		1661	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1662	this.
		1663
		1664	static gint
		1665	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1666	{
		1667	int got_events = 0;
		1668
		1669	for (n = 0; n < nfds; ++n)
		1670	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1671
		1672	if (timeout >= 0)
		1673	// create/start timer
		1674
		1675	// poll
		1676	ev_loop (EV_A_ 0);
		1677
		1678	// stop timer again
		1679	if (timeout >= 0)
		1680	ev_timer_stop (EV_A_ &to);
		1681
		1682	// stop io watchers again - their callbacks should have set
		1683	for (n = 0; n < nfds; ++n)
		1684	ev_io_stop (EV_A_ iow [n]);
		1685
		1686	return got_events;
1468	}	1687	}
1469		1688
1470		1689
1471	=head2 C<ev_embed> - when one backend isn't enough...	1690	=head2 C<ev_embed> - when one backend isn't enough...
1472		1691
…		…
1536	ev_embed_start (loop_hi, &embed);	1755	ev_embed_start (loop_hi, &embed);
1537	}	1756	}
1538	else	1757	else
1539	loop_lo = loop_hi;	1758	loop_lo = loop_hi;
1540		1759
		1760	=head3 Watcher-Specific Functions and Data Members
		1761
1541	=over 4	1762	=over 4
1542		1763
1543	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)	1764	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)
1544		1765
1545	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)	1766	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)
…		…
1571	event loop blocks next and before C<ev_check> watchers are being called,	1792	event loop blocks next and before C<ev_check> watchers are being called,
1572	and only in the child after the fork. If whoever good citizen calling	1793	and only in the child after the fork. If whoever good citizen calling
1573	C<ev_default_fork> cheats and calls it in the wrong process, the fork	1794	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1574	handlers will be invoked, too, of course.	1795	handlers will be invoked, too, of course.
1575		1796
		1797	=head3 Watcher-Specific Functions and Data Members
		1798
1576	=over 4	1799	=over 4
1577		1800
1578	=item ev_fork_init (ev_signal *, callback)	1801	=item ev_fork_init (ev_signal *, callback)
1579		1802
1580	Initialises and configures the fork watcher - it has no parameters of any	1803	Initialises and configures the fork watcher - it has no parameters of any
…		…
1676		1899
1677	To use it,	1900	To use it,
1678		1901
1679	#include <ev++.h>	1902	#include <ev++.h>
1680		1903
1681	(it is not installed by default). This automatically includes F<ev.h>	1904	This automatically includes F<ev.h> and puts all of its definitions (many
1682	and puts all of its definitions (many of them macros) into the global	1905	of them macros) into the global namespace. All C++ specific things are
1683	namespace. All C++ specific things are put into the C<ev> namespace.	1906	put into the C<ev> namespace. It should support all the same embedding
		1907	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1684		1908
1685	It should support all the same embedding options as F<ev.h>, most notably	1909	Care has been taken to keep the overhead low. The only data member the C++
1686	C<EV_MULTIPLICITY>.	1910	classes add (compared to plain C-style watchers) is the event loop pointer
		1911	that the watcher is associated with (or no additional members at all if
		1912	you disable C<EV_MULTIPLICITY> when embedding libev).
		1913
		1914	Currently, functions, and static and non-static member functions can be
		1915	used as callbacks. Other types should be easy to add as long as they only
		1916	need one additional pointer for context. If you need support for other
		1917	types of functors please contact the author (preferably after implementing
		1918	it).
1687		1919
1688	Here is a list of things available in the C<ev> namespace:	1920	Here is a list of things available in the C<ev> namespace:
1689		1921
1690	=over 4	1922	=over 4
1691		1923
…		…
1707		1939
1708	All of those classes have these methods:	1940	All of those classes have these methods:
1709		1941
1710	=over 4	1942	=over 4
1711		1943
1712	=item ev::TYPE::TYPE (object , object::method )	1944	=item ev::TYPE::TYPE ()
1713		1945
1714	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1946	=item ev::TYPE::TYPE (struct ev_loop *)
1715		1947
1716	=item ev::TYPE::~TYPE	1948	=item ev::TYPE::~TYPE
1717		1949
1718	The constructor takes a pointer to an object and a method pointer to	1950	The constructor (optionally) takes an event loop to associate the watcher
1719	the event handler callback to call in this class. The constructor calls	1951	with. If it is omitted, it will use C<EV_DEFAULT>.
1720	C<ev_init> for you, which means you have to call the C<set> method	1952
1721	before starting it. If you do not specify a loop then the constructor	1953	The constructor calls C<ev_init> for you, which means you have to call the
1722	automatically associates the default loop with this watcher.	1954	C<set> method before starting it.
		1955
		1956	It will not set a callback, however: You have to call the templated C<set>
		1957	method to set a callback before you can start the watcher.
		1958
		1959	(The reason why you have to use a method is a limitation in C++ which does
		1960	not allow explicit template arguments for constructors).
1723		1961
1724	The destructor automatically stops the watcher if it is active.	1962	The destructor automatically stops the watcher if it is active.
		1963
		1964	=item w->set<class, &class::method> (object *)
		1965
		1966	This method sets the callback method to call. The method has to have a
		1967	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1968	first argument and the C<revents> as second. The object must be given as
		1969	parameter and is stored in the C<data> member of the watcher.
		1970
		1971	This method synthesizes efficient thunking code to call your method from
		1972	the C callback that libev requires. If your compiler can inline your
		1973	callback (i.e. it is visible to it at the place of the C<set> call and
		1974	your compiler is good :), then the method will be fully inlined into the
		1975	thunking function, making it as fast as a direct C callback.
		1976
		1977	Example: simple class declaration and watcher initialisation
		1978
		1979	struct myclass
		1980	{
		1981	void io_cb (ev::io &w, int revents) { }
		1982	}
		1983
		1984	myclass obj;
		1985	ev::io iow;
		1986	iow.set <myclass, &myclass::io_cb> (&obj);
		1987
		1988	=item w->set<function> (void *data = 0)
		1989
		1990	Also sets a callback, but uses a static method or plain function as
		1991	callback. The optional C<data> argument will be stored in the watcher's
		1992	C<data> member and is free for you to use.
		1993
		1994	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		1995
		1996	See the method-C<set> above for more details.
		1997
		1998	Example:
		1999
		2000	static void io_cb (ev::io &w, int revents) { }
		2001	iow.set <io_cb> ();
1725		2002
1726	=item w->set (struct ev_loop *)	2003	=item w->set (struct ev_loop *)
1727		2004
1728	Associates a different C<struct ev_loop> with this watcher. You can only	2005	Associates a different C<struct ev_loop> with this watcher. You can only
1729	do this when the watcher is inactive (and not pending either).	2006	do this when the watcher is inactive (and not pending either).
1730		2007
1731	=item w->set ([args])	2008	=item w->set ([args])
1732		2009
1733	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2010	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1734	called at least once. Unlike the C counterpart, an active watcher gets	2011	called at least once. Unlike the C counterpart, an active watcher gets
1735	automatically stopped and restarted.	2012	automatically stopped and restarted when reconfiguring it with this
		2013	method.
1736		2014
1737	=item w->start ()	2015	=item w->start ()
1738		2016
1739	Starts the watcher. Note that there is no C<loop> argument as the	2017	Starts the watcher. Note that there is no C<loop> argument, as the
1740	constructor already takes the loop.	2018	constructor already stores the event loop.
1741		2019
1742	=item w->stop ()	2020	=item w->stop ()
1743		2021
1744	Stops the watcher if it is active. Again, no C<loop> argument.	2022	Stops the watcher if it is active. Again, no C<loop> argument.
1745		2023
…		…
1770		2048
1771	myclass ();	2049	myclass ();
1772	}	2050	}
1773		2051
1774	myclass::myclass (int fd)	2052	myclass::myclass (int fd)
1775	: io (this, &myclass::io_cb),
1776	idle (this, &myclass::idle_cb)
1777	{	2053	{
		2054	io .set <myclass, &myclass::io_cb > (this);
		2055	idle.set <myclass, &myclass::idle_cb> (this);
		2056
1778	io.start (fd, ev::READ);	2057	io.start (fd, ev::READ);
1779	}	2058	}
1780		2059
1781		2060
1782	=head1 MACRO MAGIC	2061	=head1 MACRO MAGIC
1783		2062
1784	Libev can be compiled with a variety of options, the most fundemantal is	2063	Libev can be compiled with a variety of options, the most fundemantal is
1785	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2064	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
1786	callbacks have an initial C<struct ev_loop *> argument.	2065	callbacks have an initial C<struct ev_loop *> argument.
1787		2066
1788	To make it easier to write programs that cope with either variant, the	2067	To make it easier to write programs that cope with either variant, the
1789	following macros are defined:	2068	following macros are defined:
1790		2069
…		…
1823	Similar to the other two macros, this gives you the value of the default	2102	Similar to the other two macros, this gives you the value of the default
1824	loop, if multiple loops are supported ("ev loop default").	2103	loop, if multiple loops are supported ("ev loop default").
1825		2104
1826	=back	2105	=back
1827		2106
1828	Example: Declare and initialise a check watcher, working regardless of	2107	Example: Declare and initialise a check watcher, utilising the above
1829	wether multiple loops are supported or not.	2108	macros so it will work regardless of whether multiple loops are supported
		2109	or not.
1830		2110
1831	static void	2111	static void
1832	check_cb (EV_P_ ev_timer *w, int revents)	2112	check_cb (EV_P_ ev_timer *w, int revents)
1833	{	2113	{
1834	ev_check_stop (EV_A_ w);	2114	ev_check_stop (EV_A_ w);
…		…
1836		2116
1837	ev_check check;	2117	ev_check check;
1838	ev_check_init (&check, check_cb);	2118	ev_check_init (&check, check_cb);
1839	ev_check_start (EV_DEFAULT_ &check);	2119	ev_check_start (EV_DEFAULT_ &check);
1840	ev_loop (EV_DEFAULT_ 0);	2120	ev_loop (EV_DEFAULT_ 0);
1841
1842		2121
1843	=head1 EMBEDDING	2122	=head1 EMBEDDING
1844		2123
1845	Libev can (and often is) directly embedded into host	2124	Libev can (and often is) directly embedded into host
1846	applications. Examples of applications that embed it include the Deliantra	2125	applications. Examples of applications that embed it include the Deliantra
…		…
1886	ev_vars.h	2165	ev_vars.h
1887	ev_wrap.h	2166	ev_wrap.h
1888		2167
1889	ev_win32.c required on win32 platforms only	2168	ev_win32.c required on win32 platforms only
1890		2169
1891	ev_select.c only when select backend is enabled (which is by default)	2170	ev_select.c only when select backend is enabled (which is enabled by default)
1892	ev_poll.c only when poll backend is enabled (disabled by default)	2171	ev_poll.c only when poll backend is enabled (disabled by default)
1893	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2172	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1894	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2173	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1895	ev_port.c only when the solaris port backend is enabled (disabled by default)	2174	ev_port.c only when the solaris port backend is enabled (disabled by default)
1896		2175
…		…
2059	will have the C<struct ev_loop *> as first argument, and you can create	2338	will have the C<struct ev_loop *> as first argument, and you can create
2060	additional independent event loops. Otherwise there will be no support	2339	additional independent event loops. Otherwise there will be no support
2061	for multiple event loops and there is no first event loop pointer	2340	for multiple event loops and there is no first event loop pointer
2062	argument. Instead, all functions act on the single default loop.	2341	argument. Instead, all functions act on the single default loop.
2063		2342
		2343	=item EV_MINPRI
		2344
		2345	=item EV_MAXPRI
		2346
		2347	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2348	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2349	provide for more priorities by overriding those symbols (usually defined
		2350	to be C<-2> and C<2>, respectively).
		2351
		2352	When doing priority-based operations, libev usually has to linearly search
		2353	all the priorities, so having many of them (hundreds) uses a lot of space
		2354	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2355	fine.
		2356
		2357	If your embedding app does not need any priorities, defining these both to
		2358	C<0> will save some memory and cpu.
		2359
2064	=item EV_PERIODIC_ENABLE	2360	=item EV_PERIODIC_ENABLE
2065		2361
2066	If undefined or defined to be C<1>, then periodic timers are supported. If	2362	If undefined or defined to be C<1>, then periodic timers are supported. If
		2363	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2364	code.
		2365
		2366	=item EV_IDLE_ENABLE
		2367
		2368	If undefined or defined to be C<1>, then idle watchers are supported. If
2067	defined to be C<0>, then they are not. Disabling them saves a few kB of	2369	defined to be C<0>, then they are not. Disabling them saves a few kB of
2068	code.	2370	code.
2069		2371
2070	=item EV_EMBED_ENABLE	2372	=item EV_EMBED_ENABLE
2071		2373
…		…
2138	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2440	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2139	will be compiled. It is pretty complex because it provides its own header	2441	will be compiled. It is pretty complex because it provides its own header
2140	file.	2442	file.
2141		2443
2142	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2444	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2143	that everybody includes and which overrides some autoconf choices:	2445	that everybody includes and which overrides some configure choices:
2144		2446
		2447	#define EV_MINIMAL 1
2145	#define EV_USE_POLL 0	2448	#define EV_USE_POLL 0
2146	#define EV_MULTIPLICITY 0	2449	#define EV_MULTIPLICITY 0
2147	#define EV_PERIODICS 0	2450	#define EV_PERIODIC_ENABLE 0
		2451	#define EV_STAT_ENABLE 0
		2452	#define EV_FORK_ENABLE 0
2148	#define EV_CONFIG_H <config.h>	2453	#define EV_CONFIG_H <config.h>
		2454	#define EV_MINPRI 0
		2455	#define EV_MAXPRI 0
2149		2456
2150	#include "ev++.h"	2457	#include "ev++.h"
2151		2458
2152	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2459	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2153		2460
…		…
2159		2466
2160	In this section the complexities of (many of) the algorithms used inside	2467	In this section the complexities of (many of) the algorithms used inside
2161	libev will be explained. For complexity discussions about backends see the	2468	libev will be explained. For complexity discussions about backends see the
2162	documentation for C<ev_default_init>.	2469	documentation for C<ev_default_init>.
2163		2470
		2471	All of the following are about amortised time: If an array needs to be
		2472	extended, libev needs to realloc and move the whole array, but this
		2473	happens asymptotically never with higher number of elements, so O(1) might
		2474	mean it might do a lengthy realloc operation in rare cases, but on average
		2475	it is much faster and asymptotically approaches constant time.
		2476
2164	=over 4	2477	=over 4
2165		2478
2166	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2479	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2167		2480
		2481	This means that, when you have a watcher that triggers in one hour and
		2482	there are 100 watchers that would trigger before that then inserting will
		2483	have to skip those 100 watchers.
		2484
2168	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2485	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2169		2486
		2487	That means that for changing a timer costs less than removing/adding them
		2488	as only the relative motion in the event queue has to be paid for.
		2489
2170	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2490	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2171		2491
		2492	These just add the watcher into an array or at the head of a list.
2172	=item Stopping check/prepare/idle watchers: O(1)	2493	=item Stopping check/prepare/idle watchers: O(1)
2173		2494
2174	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2495	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2175		2496
		2497	These watchers are stored in lists then need to be walked to find the
		2498	correct watcher to remove. The lists are usually short (you don't usually
		2499	have many watchers waiting for the same fd or signal).
		2500
2176	=item Finding the next timer per loop iteration: O(1)	2501	=item Finding the next timer per loop iteration: O(1)
2177		2502
2178	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2503	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2179		2504
		2505	A change means an I/O watcher gets started or stopped, which requires
		2506	libev to recalculate its status (and possibly tell the kernel).
		2507
2180	=item Activating one watcher: O(1)	2508	=item Activating one watcher: O(1)
2181		2509
		2510	=item Priority handling: O(number_of_priorities)
		2511
		2512	Priorities are implemented by allocating some space for each
		2513	priority. When doing priority-based operations, libev usually has to
		2514	linearly search all the priorities.
		2515
2182	=back	2516	=back
2183		2517
2184		2518
2185	=head1 AUTHOR	2519	=head1 AUTHOR
2186		2520

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Comparing libev/ev.pod (file contents): Revision 1.59 by root, Wed Nov 28 17:32:24 2007 UTC vs. Revision 1.83 by root, Wed Dec 12 17:55:31 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.59 by root, Wed Nov 28 17:32:24 2007 UTC vs.
Revision 1.83 by root, Wed Dec 12 17:55:31 2007 UTC