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

Comparing libev/ev.pod (file contents):
Revision 1.62 by root, Thu Nov 29 17:28:13 2007 UTC vs.
Revision 1.87 by root, Tue Dec 18 01:37:46 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.
…		…
274	a fork, you can also make libev check for a fork in each iteration by	283	a fork, you can also make libev check for a fork in each iteration by
275	enabling this flag.	284	enabling this flag.
276		285
277	This works by calling C<getpid ()> on every iteration of the loop,	286	This works by calling C<getpid ()> on every iteration of the loop,
278	and thus this might slow down your event loop if you do a lot of loop	287	and thus this might slow down your event loop if you do a lot of loop
279	iterations and little real work, but is usually not noticable (on my	288	iterations and little real work, but is usually not noticeable (on my
280	Linux system for example, C<getpid> is actually a simple 5-insn sequence	289	Linux system for example, C<getpid> is actually a simple 5-insn sequence
281	without a syscall and thus I<very> fast, but my Linux system also has	290	without a syscall and thus I<very> fast, but my Linux system also has
282	C<pthread_atfork> which is even faster).	291	C<pthread_atfork> which is even faster).
283		292
284	The big advantage of this flag is that you can forget about fork (and	293	The big advantage of this flag is that you can forget about fork (and
…		…
395	Destroys the default loop again (frees all memory and kernel state	404	Destroys the default loop again (frees all memory and kernel state
396	etc.). None of the active event watchers will be stopped in the normal	405	etc.). None of the active event watchers will be stopped in the normal
397	sense, so e.g. C<ev_is_active> might still return true. It is your	406	sense, so e.g. C<ev_is_active> might still return true. It is your
398	responsibility to either stop all watchers cleanly yoursef I<before>	407	responsibility to either stop all watchers cleanly yoursef I<before>
399	calling this function, or cope with the fact afterwards (which is usually	408	calling this function, or cope with the fact afterwards (which is usually
400	the easiest thing, youc na just ignore the watchers and/or C<free ()> them	409	the easiest thing, you can just ignore the watchers and/or C<free ()> them
401	for example).	410	for example).
		411
		412	Not that certain global state, such as signal state, will not be freed by
		413	this function, and related watchers (such as signal and child watchers)
		414	would need to be stopped manually.
		415
		416	In general it is not advisable to call this function except in the
		417	rare occasion where you really need to free e.g. the signal handling
		418	pipe fds. If you need dynamically allocated loops it is better to use
		419	C<ev_loop_new> and C<ev_loop_destroy>).
402		420
403	=item ev_loop_destroy (loop)	421	=item ev_loop_destroy (loop)
404		422
405	Like C<ev_default_destroy>, but destroys an event loop created by an	423	Like C<ev_default_destroy>, but destroys an event loop created by an
406	earlier call to C<ev_loop_new>.	424	earlier call to C<ev_loop_new>.
…		…
429	=item ev_loop_fork (loop)	447	=item ev_loop_fork (loop)
430		448
431	Like C<ev_default_fork>, but acts on an event loop created by	449	Like C<ev_default_fork>, but acts on an event loop created by
432	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	450	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
433	after fork, and how you do this is entirely your own problem.	451	after fork, and how you do this is entirely your own problem.
		452
		453	=item unsigned int ev_loop_count (loop)
		454
		455	Returns the count of loop iterations for the loop, which is identical to
		456	the number of times libev did poll for new events. It starts at C<0> and
		457	happily wraps around with enough iterations.
		458
		459	This value can sometimes be useful as a generation counter of sorts (it
		460	"ticks" the number of loop iterations), as it roughly corresponds with
		461	C<ev_prepare> and C<ev_check> calls.
434		462
435	=item unsigned int ev_backend (loop)	463	=item unsigned int ev_backend (loop)
436		464
437	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	465	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
438	use.	466	use.
…		…
472	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	500	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
473	usually a better approach for this kind of thing.	501	usually a better approach for this kind of thing.
474		502
475	Here are the gory details of what C<ev_loop> does:	503	Here are the gory details of what C<ev_loop> does:
476		504
		505	- Before the first iteration, call any pending watchers.
477	* If there are no active watchers (reference count is zero), return.	506	* If there are no active watchers (reference count is zero), return.
478	- Queue prepare watchers and then call all outstanding watchers.	507	- Queue all prepare watchers and then call all outstanding watchers.
479	- If we have been forked, recreate the kernel state.	508	- If we have been forked, recreate the kernel state.
480	- Update the kernel state with all outstanding changes.	509	- Update the kernel state with all outstanding changes.
481	- Update the "event loop time".	510	- Update the "event loop time".
482	- Calculate for how long to block.	511	- Calculate for how long to block.
483	- Block the process, waiting for any events.	512	- Block the process, waiting for any events.
…		…
722	=item bool ev_is_pending (ev_TYPE *watcher)	751	=item bool ev_is_pending (ev_TYPE *watcher)
723		752
724	Returns a true value iff the watcher is pending, (i.e. it has outstanding	753	Returns a true value iff the watcher is pending, (i.e. it has outstanding
725	events but its callback has not yet been invoked). As long as a watcher	754	events but its callback has not yet been invoked). As long as a watcher
726	is pending (but not active) you must not call an init function on it (but	755	is pending (but not active) you must not call an init function on it (but
727	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	756	C<ev_TYPE_set> is safe), you must not change its priority, and you must
728	libev (e.g. you cnanot C<free ()> it).	757	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		758	it).
729		759
730	=item callback ev_cb (ev_TYPE *watcher)	760	=item callback ev_cb (ev_TYPE *watcher)
731		761
732	Returns the callback currently set on the watcher.	762	Returns the callback currently set on the watcher.
733		763
734	=item ev_cb_set (ev_TYPE *watcher, callback)	764	=item ev_cb_set (ev_TYPE *watcher, callback)
735		765
736	Change the callback. You can change the callback at virtually any time	766	Change the callback. You can change the callback at virtually any time
737	(modulo threads).	767	(modulo threads).
		768
		769	=item ev_set_priority (ev_TYPE *watcher, priority)
		770
		771	=item int ev_priority (ev_TYPE *watcher)
		772
		773	Set and query the priority of the watcher. The priority is a small
		774	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		775	(default: C<-2>). Pending watchers with higher priority will be invoked
		776	before watchers with lower priority, but priority will not keep watchers
		777	from being executed (except for C<ev_idle> watchers).
		778
		779	This means that priorities are I<only> used for ordering callback
		780	invocation after new events have been received. This is useful, for
		781	example, to reduce latency after idling, or more often, to bind two
		782	watchers on the same event and make sure one is called first.
		783
		784	If you need to suppress invocation when higher priority events are pending
		785	you need to look at C<ev_idle> watchers, which provide this functionality.
		786
		787	You I<must not> change the priority of a watcher as long as it is active or
		788	pending.
		789
		790	The default priority used by watchers when no priority has been set is
		791	always C<0>, which is supposed to not be too high and not be too low :).
		792
		793	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		794	fine, as long as you do not mind that the priority value you query might
		795	or might not have been adjusted to be within valid range.
		796
		797	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		798
		799	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		800	C<loop> nor C<revents> need to be valid as long as the watcher callback
		801	can deal with that fact.
		802
		803	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		804
		805	If the watcher is pending, this function returns clears its pending status
		806	and returns its C<revents> bitset (as if its callback was invoked). If the
		807	watcher isn't pending it does nothing and returns C<0>.
738		808
739	=back	809	=back
740		810
741		811
742	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	812	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
848	it is best to always use non-blocking I/O: An extra C<read>(2) returning	918	it is best to always use non-blocking I/O: An extra C<read>(2) returning
849	C<EAGAIN> is far preferable to a program hanging until some data arrives.	919	C<EAGAIN> is far preferable to a program hanging until some data arrives.
850		920
851	If you cannot run the fd in non-blocking mode (for example you should not	921	If you cannot run the fd in non-blocking mode (for example you should not
852	play around with an Xlib connection), then you have to seperately re-test	922	play around with an Xlib connection), then you have to seperately re-test
853	wether a file descriptor is really ready with a known-to-be good interface	923	whether a file descriptor is really ready with a known-to-be good interface
854	such as poll (fortunately in our Xlib example, Xlib already does this on	924	such as poll (fortunately in our Xlib example, Xlib already does this on
855	its own, so its quite safe to use).	925	its own, so its quite safe to use).
		926
		927	=head3 The special problem of disappearing file descriptors
		928
		929	Some backends (e.g kqueue, epoll) need to be told about closing a file
		930	descriptor (either by calling C<close> explicitly or by any other means,
		931	such as C<dup>). The reason is that you register interest in some file
		932	descriptor, but when it goes away, the operating system will silently drop
		933	this interest. If another file descriptor with the same number then is
		934	registered with libev, there is no efficient way to see that this is, in
		935	fact, a different file descriptor.
		936
		937	To avoid having to explicitly tell libev about such cases, libev follows
		938	the following policy: Each time C<ev_io_set> is being called, libev
		939	will assume that this is potentially a new file descriptor, otherwise
		940	it is assumed that the file descriptor stays the same. That means that
		941	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		942	descriptor even if the file descriptor number itself did not change.
		943
		944	This is how one would do it normally anyway, the important point is that
		945	the libev application should not optimise around libev but should leave
		946	optimisations to libev.
		947
		948
		949	=head3 Watcher-Specific Functions
856		950
857	=over 4	951	=over 4
858		952
859	=item ev_io_init (ev_io *, callback, int fd, int events)	953	=item ev_io_init (ev_io *, callback, int fd, int events)
860		954
…		…
913	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1007	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
914		1008
915	The callback is guarenteed to be invoked only when its timeout has passed,	1009	The callback is guarenteed to be invoked only when its timeout has passed,
916	but if multiple timers become ready during the same loop iteration then	1010	but if multiple timers become ready during the same loop iteration then
917	order of execution is undefined.	1011	order of execution is undefined.
		1012
		1013	=head3 Watcher-Specific Functions and Data Members
918		1014
919	=over 4	1015	=over 4
920		1016
921	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1017	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
922		1018
…		…
1018	but on wallclock time (absolute time). You can tell a periodic watcher	1114	but on wallclock time (absolute time). You can tell a periodic watcher
1019	to trigger "at" some specific point in time. For example, if you tell a	1115	to trigger "at" some specific point in time. For example, if you tell a
1020	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1116	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
1021	+ 10.>) and then reset your system clock to the last year, then it will	1117	+ 10.>) and then reset your system clock to the last year, then it will
1022	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1118	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
1023	roughly 10 seconds later and of course not if you reset your system time	1119	roughly 10 seconds later).
1024	again).
1025		1120
1026	They can also be used to implement vastly more complex timers, such as	1121	They can also be used to implement vastly more complex timers, such as
1027	triggering an event on eahc midnight, local time.	1122	triggering an event on each midnight, local time or other, complicated,
		1123	rules.
1028		1124
1029	As with timers, the callback is guarenteed to be invoked only when the	1125	As with timers, the callback is guarenteed to be invoked only when the
1030	time (C<at>) has been passed, but if multiple periodic timers become ready	1126	time (C<at>) has been passed, but if multiple periodic timers become ready
1031	during the same loop iteration then order of execution is undefined.	1127	during the same loop iteration then order of execution is undefined.
1032		1128
		1129	=head3 Watcher-Specific Functions and Data Members
		1130
1033	=over 4	1131	=over 4
1034		1132
1035	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1133	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
1036		1134
1037	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1135	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
1039	Lots of arguments, lets sort it out... There are basically three modes of	1137	Lots of arguments, lets sort it out... There are basically three modes of
1040	operation, and we will explain them from simplest to complex:	1138	operation, and we will explain them from simplest to complex:
1041		1139
1042	=over 4	1140	=over 4
1043		1141
1044	=item * absolute timer (interval = reschedule_cb = 0)	1142	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1045		1143
1046	In this configuration the watcher triggers an event at the wallclock time	1144	In this configuration the watcher triggers an event at the wallclock time
1047	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1145	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
1048	that is, if it is to be run at January 1st 2011 then it will run when the	1146	that is, if it is to be run at January 1st 2011 then it will run when the
1049	system time reaches or surpasses this time.	1147	system time reaches or surpasses this time.
1050		1148
1051	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1149	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1052		1150
1053	In this mode the watcher will always be scheduled to time out at the next	1151	In this mode the watcher will always be scheduled to time out at the next
1054	C<at + N * interval> time (for some integer N) and then repeat, regardless	1152	C<at + N * interval> time (for some integer N, which can also be negative)
1055	of any time jumps.	1153	and then repeat, regardless of any time jumps.
1056		1154
1057	This can be used to create timers that do not drift with respect to system	1155	This can be used to create timers that do not drift with respect to system
1058	time:	1156	time:
1059		1157
1060	ev_periodic_set (&periodic, 0., 3600., 0);	1158	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1066		1164
1067	Another way to think about it (for the mathematically inclined) is that	1165	Another way to think about it (for the mathematically inclined) is that
1068	C<ev_periodic> will try to run the callback in this mode at the next possible	1166	C<ev_periodic> will try to run the callback in this mode at the next possible
1069	time where C<time = at (mod interval)>, regardless of any time jumps.	1167	time where C<time = at (mod interval)>, regardless of any time jumps.
1070		1168
		1169	For numerical stability it is preferable that the C<at> value is near
		1170	C<ev_now ()> (the current time), but there is no range requirement for
		1171	this value.
		1172
1071	=item * manual reschedule mode (reschedule_cb = callback)	1173	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1072		1174
1073	In this mode the values for C<interval> and C<at> are both being	1175	In this mode the values for C<interval> and C<at> are both being
1074	ignored. Instead, each time the periodic watcher gets scheduled, the	1176	ignored. Instead, each time the periodic watcher gets scheduled, the
1075	reschedule callback will be called with the watcher as first, and the	1177	reschedule callback will be called with the watcher as first, and the
1076	current time as second argument.	1178	current time as second argument.
1077		1179
1078	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1180	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1079	ever, or make any event loop modifications>. If you need to stop it,	1181	ever, or make any event loop modifications>. If you need to stop it,
1080	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1182	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1081	starting a prepare watcher).	1183	starting an C<ev_prepare> watcher, which is legal).
1082		1184
1083	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	1185	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
1084	ev_tstamp now)>, e.g.:	1186	ev_tstamp now)>, e.g.:
1085		1187
1086	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1188	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
1109	Simply stops and restarts the periodic watcher again. This is only useful	1211	Simply stops and restarts the periodic watcher again. This is only useful
1110	when you changed some parameters or the reschedule callback would return	1212	when you changed some parameters or the reschedule callback would return
1111	a different time than the last time it was called (e.g. in a crond like	1213	a different time than the last time it was called (e.g. in a crond like
1112	program when the crontabs have changed).	1214	program when the crontabs have changed).
1113		1215
		1216	=item ev_tstamp offset [read-write]
		1217
		1218	When repeating, this contains the offset value, otherwise this is the
		1219	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1220
		1221	Can be modified any time, but changes only take effect when the periodic
		1222	timer fires or C<ev_periodic_again> is being called.
		1223
1114	=item ev_tstamp interval [read-write]	1224	=item ev_tstamp interval [read-write]
1115		1225
1116	The current interval value. Can be modified any time, but changes only	1226	The current interval value. Can be modified any time, but changes only
1117	take effect when the periodic timer fires or C<ev_periodic_again> is being	1227	take effect when the periodic timer fires or C<ev_periodic_again> is being
1118	called.	1228	called.
…		…
1120	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]	1230	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
1121		1231
1122	The current reschedule callback, or C<0>, if this functionality is	1232	The current reschedule callback, or C<0>, if this functionality is
1123	switched off. Can be changed any time, but changes only take effect when	1233	switched off. Can be changed any time, but changes only take effect when
1124	the periodic timer fires or C<ev_periodic_again> is being called.	1234	the periodic timer fires or C<ev_periodic_again> is being called.
		1235
		1236	=item ev_tstamp at [read-only]
		1237
		1238	When active, contains the absolute time that the watcher is supposed to
		1239	trigger next.
1125		1240
1126	=back	1241	=back
1127		1242
1128	Example: Call a callback every hour, or, more precisely, whenever the	1243	Example: Call a callback every hour, or, more precisely, whenever the
1129	system clock is divisible by 3600. The callback invocation times have	1244	system clock is divisible by 3600. The callback invocation times have
…		…
1171	with the kernel (thus it coexists with your own signal handlers as long	1286	with the kernel (thus it coexists with your own signal handlers as long
1172	as you don't register any with libev). Similarly, when the last signal	1287	as you don't register any with libev). Similarly, when the last signal
1173	watcher for a signal is stopped libev will reset the signal handler to	1288	watcher for a signal is stopped libev will reset the signal handler to
1174	SIG_DFL (regardless of what it was set to before).	1289	SIG_DFL (regardless of what it was set to before).
1175		1290
		1291	=head3 Watcher-Specific Functions and Data Members
		1292
1176	=over 4	1293	=over 4
1177		1294
1178	=item ev_signal_init (ev_signal *, callback, int signum)	1295	=item ev_signal_init (ev_signal *, callback, int signum)
1179		1296
1180	=item ev_signal_set (ev_signal *, int signum)	1297	=item ev_signal_set (ev_signal *, int signum)
…		…
1191		1308
1192	=head2 C<ev_child> - watch out for process status changes	1309	=head2 C<ev_child> - watch out for process status changes
1193		1310
1194	Child watchers trigger when your process receives a SIGCHLD in response to	1311	Child watchers trigger when your process receives a SIGCHLD in response to
1195	some child status changes (most typically when a child of yours dies).	1312	some child status changes (most typically when a child of yours dies).
		1313
		1314	=head3 Watcher-Specific Functions and Data Members
1196		1315
1197	=over 4	1316	=over 4
1198		1317
1199	=item ev_child_init (ev_child *, callback, int pid)	1318	=item ev_child_init (ev_child *, callback, int pid)
1200		1319
…		…
1268	reader). Inotify will be used to give hints only and should not change the	1387	reader). Inotify will be used to give hints only and should not change the
1269	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1388	semantics of C<ev_stat> watchers, which means that libev sometimes needs
1270	to fall back to regular polling again even with inotify, but changes are	1389	to fall back to regular polling again even with inotify, but changes are
1271	usually detected immediately, and if the file exists there will be no	1390	usually detected immediately, and if the file exists there will be no
1272	polling.	1391	polling.
		1392
		1393	=head3 Watcher-Specific Functions and Data Members
1273		1394
1274	=over 4	1395	=over 4
1275		1396
1276	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1397	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1277		1398
…		…
1341	ev_stat_start (loop, &passwd);	1462	ev_stat_start (loop, &passwd);
1342		1463
1343		1464
1344	=head2 C<ev_idle> - when you've got nothing better to do...	1465	=head2 C<ev_idle> - when you've got nothing better to do...
1345		1466
1346	Idle watchers trigger events when there are no other events are pending	1467	Idle watchers trigger events when no other events of the same or higher
1347	(prepare, check and other idle watchers do not count). That is, as long	1468	priority are pending (prepare, check and other idle watchers do not
1348	as your process is busy handling sockets or timeouts (or even signals,	1469	count).
1349	imagine) it will not be triggered. But when your process is idle all idle	1470
1350	watchers are being called again and again, once per event loop iteration -	1471	That is, as long as your process is busy handling sockets or timeouts
		1472	(or even signals, imagine) of the same or higher priority it will not be
		1473	triggered. But when your process is idle (or only lower-priority watchers
		1474	are pending), the idle watchers are being called once per event loop
1351	until stopped, that is, or your process receives more events and becomes	1475	iteration - until stopped, that is, or your process receives more events
1352	busy.	1476	and becomes busy again with higher priority stuff.
1353		1477
1354	The most noteworthy effect is that as long as any idle watchers are	1478	The most noteworthy effect is that as long as any idle watchers are
1355	active, the process will not block when waiting for new events.	1479	active, the process will not block when waiting for new events.
1356		1480
1357	Apart from keeping your process non-blocking (which is a useful	1481	Apart from keeping your process non-blocking (which is a useful
1358	effect on its own sometimes), idle watchers are a good place to do	1482	effect on its own sometimes), idle watchers are a good place to do
1359	"pseudo-background processing", or delay processing stuff to after the	1483	"pseudo-background processing", or delay processing stuff to after the
1360	event loop has handled all outstanding events.	1484	event loop has handled all outstanding events.
		1485
		1486	=head3 Watcher-Specific Functions and Data Members
1361		1487
1362	=over 4	1488	=over 4
1363		1489
1364	=item ev_idle_init (ev_signal *, callback)	1490	=item ev_idle_init (ev_signal *, callback)
1365		1491
…		…
1423	with priority higher than or equal to the event loop and one coroutine	1549	with priority higher than or equal to the event loop and one coroutine
1424	of lower priority, but only once, using idle watchers to keep the event	1550	of lower priority, but only once, using idle watchers to keep the event
1425	loop from blocking if lower-priority coroutines are active, thus mapping	1551	loop from blocking if lower-priority coroutines are active, thus mapping
1426	low-priority coroutines to idle/background tasks).	1552	low-priority coroutines to idle/background tasks).
1427		1553
		1554	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1555	priority, to ensure that they are being run before any other watchers
		1556	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1557	too) should not activate ("feed") events into libev. While libev fully
		1558	supports this, they will be called before other C<ev_check> watchers did
		1559	their job. As C<ev_check> watchers are often used to embed other event
		1560	loops those other event loops might be in an unusable state until their
		1561	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1562	others).
		1563
		1564	=head3 Watcher-Specific Functions and Data Members
		1565
1428	=over 4	1566	=over 4
1429		1567
1430	=item ev_prepare_init (ev_prepare *, callback)	1568	=item ev_prepare_init (ev_prepare *, callback)
1431		1569
1432	=item ev_check_init (ev_check *, callback)	1570	=item ev_check_init (ev_check *, callback)
…		…
1435	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1573	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1436	macros, but using them is utterly, utterly and completely pointless.	1574	macros, but using them is utterly, utterly and completely pointless.
1437		1575
1438	=back	1576	=back
1439		1577
1440	Example: To include a library such as adns, you would add IO watchers	1578	There are a number of principal ways to embed other event loops or modules
1441	and a timeout watcher in a prepare handler, as required by libadns, and	1579	into libev. Here are some ideas on how to include libadns into libev
		1580	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1581	use for an actually working example. Another Perl module named C<EV::Glib>
		1582	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1583	into the Glib event loop).
		1584
		1585	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1442	in a check watcher, destroy them and call into libadns. What follows is	1586	and in a check watcher, destroy them and call into libadns. What follows
1443	pseudo-code only of course:	1587	is pseudo-code only of course. This requires you to either use a low
		1588	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1589	the callbacks for the IO/timeout watchers might not have been called yet.
1444		1590
1445	static ev_io iow [nfd];	1591	static ev_io iow [nfd];
1446	static ev_timer tw;	1592	static ev_timer tw;
1447		1593
1448	static void	1594	static void
1449	io_cb (ev_loop loop, ev_io w, int revents)	1595	io_cb (ev_loop loop, ev_io w, int revents)
1450	{	1596	{
1451	// set the relevant poll flags
1452	// could also call adns_processreadable etc. here
1453	struct pollfd fd = (struct pollfd )w->data;
1454	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1455	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1456	}	1597	}
1457		1598
1458	// create io watchers for each fd and a timer before blocking	1599	// create io watchers for each fd and a timer before blocking
1459	static void	1600	static void
1460	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1601	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1461	{	1602	{
1462	int timeout = 3600000;truct pollfd fds [nfd];	1603	int timeout = 3600000;
		1604	struct pollfd fds [nfd];
1463	// actual code will need to loop here and realloc etc.	1605	// actual code will need to loop here and realloc etc.
1464	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1606	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1465		1607
1466	/* the callback is illegal, but won't be called as we stop during check */	1608	/* the callback is illegal, but won't be called as we stop during check */
1467	ev_timer_init (&tw, 0, timeout * 1e-3);	1609	ev_timer_init (&tw, 0, timeout * 1e-3);
1468	ev_timer_start (loop, &tw);	1610	ev_timer_start (loop, &tw);
1469		1611
1470	// create on ev_io per pollfd	1612	// create one ev_io per pollfd
1471	for (int i = 0; i < nfd; ++i)	1613	for (int i = 0; i < nfd; ++i)
1472	{	1614	{
1473	ev_io_init (iow + i, io_cb, fds [i].fd,	1615	ev_io_init (iow + i, io_cb, fds [i].fd,
1474	((fds [i].events & POLLIN ? EV_READ : 0)	1616	((fds [i].events & POLLIN ? EV_READ : 0)
1475	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1617	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1476		1618
1477	fds [i].revents = 0;	1619	fds [i].revents = 0;
1478	iow [i].data = fds + i;
1479	ev_io_start (loop, iow + i);	1620	ev_io_start (loop, iow + i);
1480	}	1621	}
1481	}	1622	}
1482		1623
1483	// stop all watchers after blocking	1624	// stop all watchers after blocking
…		…
1485	adns_check_cb (ev_loop loop, ev_check w, int revents)	1626	adns_check_cb (ev_loop loop, ev_check w, int revents)
1486	{	1627	{
1487	ev_timer_stop (loop, &tw);	1628	ev_timer_stop (loop, &tw);
1488		1629
1489	for (int i = 0; i < nfd; ++i)	1630	for (int i = 0; i < nfd; ++i)
		1631	{
		1632	// set the relevant poll flags
		1633	// could also call adns_processreadable etc. here
		1634	struct pollfd *fd = fds + i;
		1635	int revents = ev_clear_pending (iow + i);
		1636	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1637	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1638
		1639	// now stop the watcher
1490	ev_io_stop (loop, iow + i);	1640	ev_io_stop (loop, iow + i);
		1641	}
1491		1642
1492	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1643	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1644	}
		1645
		1646	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1647	in the prepare watcher and would dispose of the check watcher.
		1648
		1649	Method 3: If the module to be embedded supports explicit event
		1650	notification (adns does), you can also make use of the actual watcher
		1651	callbacks, and only destroy/create the watchers in the prepare watcher.
		1652
		1653	static void
		1654	timer_cb (EV_P_ ev_timer *w, int revents)
		1655	{
		1656	adns_state ads = (adns_state)w->data;
		1657	update_now (EV_A);
		1658
		1659	adns_processtimeouts (ads, &tv_now);
		1660	}
		1661
		1662	static void
		1663	io_cb (EV_P_ ev_io *w, int revents)
		1664	{
		1665	adns_state ads = (adns_state)w->data;
		1666	update_now (EV_A);
		1667
		1668	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1669	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1670	}
		1671
		1672	// do not ever call adns_afterpoll
		1673
		1674	Method 4: Do not use a prepare or check watcher because the module you
		1675	want to embed is too inflexible to support it. Instead, youc na override
		1676	their poll function. The drawback with this solution is that the main
		1677	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1678	this.
		1679
		1680	static gint
		1681	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1682	{
		1683	int got_events = 0;
		1684
		1685	for (n = 0; n < nfds; ++n)
		1686	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1687
		1688	if (timeout >= 0)
		1689	// create/start timer
		1690
		1691	// poll
		1692	ev_loop (EV_A_ 0);
		1693
		1694	// stop timer again
		1695	if (timeout >= 0)
		1696	ev_timer_stop (EV_A_ &to);
		1697
		1698	// stop io watchers again - their callbacks should have set
		1699	for (n = 0; n < nfds; ++n)
		1700	ev_io_stop (EV_A_ iow [n]);
		1701
		1702	return got_events;
1493	}	1703	}
1494		1704
1495		1705
1496	=head2 C<ev_embed> - when one backend isn't enough...	1706	=head2 C<ev_embed> - when one backend isn't enough...
1497		1707
…		…
1561	ev_embed_start (loop_hi, &embed);	1771	ev_embed_start (loop_hi, &embed);
1562	}	1772	}
1563	else	1773	else
1564	loop_lo = loop_hi;	1774	loop_lo = loop_hi;
1565		1775
		1776	=head3 Watcher-Specific Functions and Data Members
		1777
1566	=over 4	1778	=over 4
1567		1779
1568	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)	1780	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)
1569		1781
1570	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)	1782	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)
…		…
1596	event loop blocks next and before C<ev_check> watchers are being called,	1808	event loop blocks next and before C<ev_check> watchers are being called,
1597	and only in the child after the fork. If whoever good citizen calling	1809	and only in the child after the fork. If whoever good citizen calling
1598	C<ev_default_fork> cheats and calls it in the wrong process, the fork	1810	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1599	handlers will be invoked, too, of course.	1811	handlers will be invoked, too, of course.
1600		1812
		1813	=head3 Watcher-Specific Functions and Data Members
		1814
1601	=over 4	1815	=over 4
1602		1816
1603	=item ev_fork_init (ev_signal *, callback)	1817	=item ev_fork_init (ev_signal *, callback)
1604		1818
1605	Initialises and configures the fork watcher - it has no parameters of any	1819	Initialises and configures the fork watcher - it has no parameters of any
…		…
1701		1915
1702	To use it,	1916	To use it,
1703		1917
1704	#include <ev++.h>	1918	#include <ev++.h>
1705		1919
1706	(it is not installed by default). This automatically includes F<ev.h>	1920	This automatically includes F<ev.h> and puts all of its definitions (many
1707	and puts all of its definitions (many of them macros) into the global	1921	of them macros) into the global namespace. All C++ specific things are
1708	namespace. All C++ specific things are put into the C<ev> namespace.	1922	put into the C<ev> namespace. It should support all the same embedding
		1923	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1709		1924
1710	It should support all the same embedding options as F<ev.h>, most notably	1925	Care has been taken to keep the overhead low. The only data member the C++
1711	C<EV_MULTIPLICITY>.	1926	classes add (compared to plain C-style watchers) is the event loop pointer
		1927	that the watcher is associated with (or no additional members at all if
		1928	you disable C<EV_MULTIPLICITY> when embedding libev).
		1929
		1930	Currently, functions, and static and non-static member functions can be
		1931	used as callbacks. Other types should be easy to add as long as they only
		1932	need one additional pointer for context. If you need support for other
		1933	types of functors please contact the author (preferably after implementing
		1934	it).
1712		1935
1713	Here is a list of things available in the C<ev> namespace:	1936	Here is a list of things available in the C<ev> namespace:
1714		1937
1715	=over 4	1938	=over 4
1716		1939
…		…
1732		1955
1733	All of those classes have these methods:	1956	All of those classes have these methods:
1734		1957
1735	=over 4	1958	=over 4
1736		1959
1737	=item ev::TYPE::TYPE (object , object::method )	1960	=item ev::TYPE::TYPE ()
1738		1961
1739	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1962	=item ev::TYPE::TYPE (struct ev_loop *)
1740		1963
1741	=item ev::TYPE::~TYPE	1964	=item ev::TYPE::~TYPE
1742		1965
1743	The constructor takes a pointer to an object and a method pointer to	1966	The constructor (optionally) takes an event loop to associate the watcher
1744	the event handler callback to call in this class. The constructor calls	1967	with. If it is omitted, it will use C<EV_DEFAULT>.
1745	C<ev_init> for you, which means you have to call the C<set> method	1968
1746	before starting it. If you do not specify a loop then the constructor	1969	The constructor calls C<ev_init> for you, which means you have to call the
1747	automatically associates the default loop with this watcher.	1970	C<set> method before starting it.
		1971
		1972	It will not set a callback, however: You have to call the templated C<set>
		1973	method to set a callback before you can start the watcher.
		1974
		1975	(The reason why you have to use a method is a limitation in C++ which does
		1976	not allow explicit template arguments for constructors).
1748		1977
1749	The destructor automatically stops the watcher if it is active.	1978	The destructor automatically stops the watcher if it is active.
		1979
		1980	=item w->set<class, &class::method> (object *)
		1981
		1982	This method sets the callback method to call. The method has to have a
		1983	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1984	first argument and the C<revents> as second. The object must be given as
		1985	parameter and is stored in the C<data> member of the watcher.
		1986
		1987	This method synthesizes efficient thunking code to call your method from
		1988	the C callback that libev requires. If your compiler can inline your
		1989	callback (i.e. it is visible to it at the place of the C<set> call and
		1990	your compiler is good :), then the method will be fully inlined into the
		1991	thunking function, making it as fast as a direct C callback.
		1992
		1993	Example: simple class declaration and watcher initialisation
		1994
		1995	struct myclass
		1996	{
		1997	void io_cb (ev::io &w, int revents) { }
		1998	}
		1999
		2000	myclass obj;
		2001	ev::io iow;
		2002	iow.set <myclass, &myclass::io_cb> (&obj);
		2003
		2004	=item w->set<function> (void *data = 0)
		2005
		2006	Also sets a callback, but uses a static method or plain function as
		2007	callback. The optional C<data> argument will be stored in the watcher's
		2008	C<data> member and is free for you to use.
		2009
		2010	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2011
		2012	See the method-C<set> above for more details.
		2013
		2014	Example:
		2015
		2016	static void io_cb (ev::io &w, int revents) { }
		2017	iow.set <io_cb> ();
1750		2018
1751	=item w->set (struct ev_loop *)	2019	=item w->set (struct ev_loop *)
1752		2020
1753	Associates a different C<struct ev_loop> with this watcher. You can only	2021	Associates a different C<struct ev_loop> with this watcher. You can only
1754	do this when the watcher is inactive (and not pending either).	2022	do this when the watcher is inactive (and not pending either).
1755		2023
1756	=item w->set ([args])	2024	=item w->set ([args])
1757		2025
1758	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2026	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1759	called at least once. Unlike the C counterpart, an active watcher gets	2027	called at least once. Unlike the C counterpart, an active watcher gets
1760	automatically stopped and restarted.	2028	automatically stopped and restarted when reconfiguring it with this
		2029	method.
1761		2030
1762	=item w->start ()	2031	=item w->start ()
1763		2032
1764	Starts the watcher. Note that there is no C<loop> argument as the	2033	Starts the watcher. Note that there is no C<loop> argument, as the
1765	constructor already takes the loop.	2034	constructor already stores the event loop.
1766		2035
1767	=item w->stop ()	2036	=item w->stop ()
1768		2037
1769	Stops the watcher if it is active. Again, no C<loop> argument.	2038	Stops the watcher if it is active. Again, no C<loop> argument.
1770		2039
1771	=item w->again () C<ev::timer>, C<ev::periodic> only	2040	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1772		2041
1773	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2042	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1774	C<ev_TYPE_again> function.	2043	C<ev_TYPE_again> function.
1775		2044
1776	=item w->sweep () C<ev::embed> only	2045	=item w->sweep () (C<ev::embed> only)
1777		2046
1778	Invokes C<ev_embed_sweep>.	2047	Invokes C<ev_embed_sweep>.
1779		2048
1780	=item w->update () C<ev::stat> only	2049	=item w->update () (C<ev::stat> only)
1781		2050
1782	Invokes C<ev_stat_stat>.	2051	Invokes C<ev_stat_stat>.
1783		2052
1784	=back	2053	=back
1785		2054
…		…
1795		2064
1796	myclass ();	2065	myclass ();
1797	}	2066	}
1798		2067
1799	myclass::myclass (int fd)	2068	myclass::myclass (int fd)
1800	: io (this, &myclass::io_cb),
1801	idle (this, &myclass::idle_cb)
1802	{	2069	{
		2070	io .set <myclass, &myclass::io_cb > (this);
		2071	idle.set <myclass, &myclass::idle_cb> (this);
		2072
1803	io.start (fd, ev::READ);	2073	io.start (fd, ev::READ);
1804	}	2074	}
1805		2075
1806		2076
1807	=head1 MACRO MAGIC	2077	=head1 MACRO MAGIC
1808		2078
1809	Libev can be compiled with a variety of options, the most fundemantal is	2079	Libev can be compiled with a variety of options, the most fundamantal
1810	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2080	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1811	callbacks have an initial C<struct ev_loop *> argument.	2081	functions and callbacks have an initial C<struct ev_loop *> argument.
1812		2082
1813	To make it easier to write programs that cope with either variant, the	2083	To make it easier to write programs that cope with either variant, the
1814	following macros are defined:	2084	following macros are defined:
1815		2085
1816	=over 4	2086	=over 4
…		…
1848	Similar to the other two macros, this gives you the value of the default	2118	Similar to the other two macros, this gives you the value of the default
1849	loop, if multiple loops are supported ("ev loop default").	2119	loop, if multiple loops are supported ("ev loop default").
1850		2120
1851	=back	2121	=back
1852		2122
1853	Example: Declare and initialise a check watcher, working regardless of	2123	Example: Declare and initialise a check watcher, utilising the above
1854	wether multiple loops are supported or not.	2124	macros so it will work regardless of whether multiple loops are supported
		2125	or not.
1855		2126
1856	static void	2127	static void
1857	check_cb (EV_P_ ev_timer *w, int revents)	2128	check_cb (EV_P_ ev_timer *w, int revents)
1858	{	2129	{
1859	ev_check_stop (EV_A_ w);	2130	ev_check_stop (EV_A_ w);
…		…
1861		2132
1862	ev_check check;	2133	ev_check check;
1863	ev_check_init (&check, check_cb);	2134	ev_check_init (&check, check_cb);
1864	ev_check_start (EV_DEFAULT_ &check);	2135	ev_check_start (EV_DEFAULT_ &check);
1865	ev_loop (EV_DEFAULT_ 0);	2136	ev_loop (EV_DEFAULT_ 0);
1866
1867		2137
1868	=head1 EMBEDDING	2138	=head1 EMBEDDING
1869		2139
1870	Libev can (and often is) directly embedded into host	2140	Libev can (and often is) directly embedded into host
1871	applications. Examples of applications that embed it include the Deliantra	2141	applications. Examples of applications that embed it include the Deliantra
…		…
1911	ev_vars.h	2181	ev_vars.h
1912	ev_wrap.h	2182	ev_wrap.h
1913		2183
1914	ev_win32.c required on win32 platforms only	2184	ev_win32.c required on win32 platforms only
1915		2185
1916	ev_select.c only when select backend is enabled (which is by default)	2186	ev_select.c only when select backend is enabled (which is enabled by default)
1917	ev_poll.c only when poll backend is enabled (disabled by default)	2187	ev_poll.c only when poll backend is enabled (disabled by default)
1918	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2188	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1919	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2189	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1920	ev_port.c only when the solaris port backend is enabled (disabled by default)	2190	ev_port.c only when the solaris port backend is enabled (disabled by default)
1921		2191
…		…
2084	will have the C<struct ev_loop *> as first argument, and you can create	2354	will have the C<struct ev_loop *> as first argument, and you can create
2085	additional independent event loops. Otherwise there will be no support	2355	additional independent event loops. Otherwise there will be no support
2086	for multiple event loops and there is no first event loop pointer	2356	for multiple event loops and there is no first event loop pointer
2087	argument. Instead, all functions act on the single default loop.	2357	argument. Instead, all functions act on the single default loop.
2088		2358
		2359	=item EV_MINPRI
		2360
		2361	=item EV_MAXPRI
		2362
		2363	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2364	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2365	provide for more priorities by overriding those symbols (usually defined
		2366	to be C<-2> and C<2>, respectively).
		2367
		2368	When doing priority-based operations, libev usually has to linearly search
		2369	all the priorities, so having many of them (hundreds) uses a lot of space
		2370	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2371	fine.
		2372
		2373	If your embedding app does not need any priorities, defining these both to
		2374	C<0> will save some memory and cpu.
		2375
2089	=item EV_PERIODIC_ENABLE	2376	=item EV_PERIODIC_ENABLE
2090		2377
2091	If undefined or defined to be C<1>, then periodic timers are supported. If	2378	If undefined or defined to be C<1>, then periodic timers are supported. If
		2379	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2380	code.
		2381
		2382	=item EV_IDLE_ENABLE
		2383
		2384	If undefined or defined to be C<1>, then idle watchers are supported. If
2092	defined to be C<0>, then they are not. Disabling them saves a few kB of	2385	defined to be C<0>, then they are not. Disabling them saves a few kB of
2093	code.	2386	code.
2094		2387
2095	=item EV_EMBED_ENABLE	2388	=item EV_EMBED_ENABLE
2096		2389
…		…
2163	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2456	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2164	will be compiled. It is pretty complex because it provides its own header	2457	will be compiled. It is pretty complex because it provides its own header
2165	file.	2458	file.
2166		2459
2167	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2460	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2168	that everybody includes and which overrides some autoconf choices:	2461	that everybody includes and which overrides some configure choices:
2169		2462
		2463	#define EV_MINIMAL 1
2170	#define EV_USE_POLL 0	2464	#define EV_USE_POLL 0
2171	#define EV_MULTIPLICITY 0	2465	#define EV_MULTIPLICITY 0
2172	#define EV_PERIODICS 0	2466	#define EV_PERIODIC_ENABLE 0
		2467	#define EV_STAT_ENABLE 0
		2468	#define EV_FORK_ENABLE 0
2173	#define EV_CONFIG_H <config.h>	2469	#define EV_CONFIG_H <config.h>
		2470	#define EV_MINPRI 0
		2471	#define EV_MAXPRI 0
2174		2472
2175	#include "ev++.h"	2473	#include "ev++.h"
2176		2474
2177	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2475	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2178		2476
…		…
2184		2482
2185	In this section the complexities of (many of) the algorithms used inside	2483	In this section the complexities of (many of) the algorithms used inside
2186	libev will be explained. For complexity discussions about backends see the	2484	libev will be explained. For complexity discussions about backends see the
2187	documentation for C<ev_default_init>.	2485	documentation for C<ev_default_init>.
2188		2486
		2487	All of the following are about amortised time: If an array needs to be
		2488	extended, libev needs to realloc and move the whole array, but this
		2489	happens asymptotically never with higher number of elements, so O(1) might
		2490	mean it might do a lengthy realloc operation in rare cases, but on average
		2491	it is much faster and asymptotically approaches constant time.
		2492
2189	=over 4	2493	=over 4
2190		2494
2191	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2495	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2192		2496
		2497	This means that, when you have a watcher that triggers in one hour and
		2498	there are 100 watchers that would trigger before that then inserting will
		2499	have to skip those 100 watchers.
		2500
2193	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2501	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2194		2502
		2503	That means that for changing a timer costs less than removing/adding them
		2504	as only the relative motion in the event queue has to be paid for.
		2505
2195	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2506	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2196		2507
		2508	These just add the watcher into an array or at the head of a list.
2197	=item Stopping check/prepare/idle watchers: O(1)	2509	=item Stopping check/prepare/idle watchers: O(1)
2198		2510
2199	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2511	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2200		2512
		2513	These watchers are stored in lists then need to be walked to find the
		2514	correct watcher to remove. The lists are usually short (you don't usually
		2515	have many watchers waiting for the same fd or signal).
		2516
2201	=item Finding the next timer per loop iteration: O(1)	2517	=item Finding the next timer per loop iteration: O(1)
2202		2518
2203	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2519	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2204		2520
		2521	A change means an I/O watcher gets started or stopped, which requires
		2522	libev to recalculate its status (and possibly tell the kernel).
		2523
2205	=item Activating one watcher: O(1)	2524	=item Activating one watcher: O(1)
2206		2525
		2526	=item Priority handling: O(number_of_priorities)
		2527
		2528	Priorities are implemented by allocating some space for each
		2529	priority. When doing priority-based operations, libev usually has to
		2530	linearly search all the priorities.
		2531
2207	=back	2532	=back
2208		2533
2209		2534
2210	=head1 AUTHOR	2535	=head1 AUTHOR
2211		2536

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Comparing libev/ev.pod (file contents): Revision 1.62 by root, Thu Nov 29 17:28:13 2007 UTC vs. Revision 1.87 by root, Tue Dec 18 01:37:46 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.62 by root, Thu Nov 29 17:28:13 2007 UTC vs.
Revision 1.87 by root, Tue Dec 18 01:37:46 2007 UTC