[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 1.92 by root, Fri Dec 21 01:26:04 2007 UTC

…		…
48	return 0;	48	return 0;
49	}	49	}
50		50
51	=head1 DESCRIPTION	51	=head1 DESCRIPTION
52		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>.
		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 occurring), 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
57	To do this, it must take more or less complete control over your process	61	To do this, it must take more or less complete control over your process
58	(or thread) by executing the I<event loop> handler, and will then	62	(or thread) by executing the I<event loop> handler, and will then
59	communicate events via a callback mechanism.	63	communicate events via a callback mechanism.
…		…
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.
…		…
266	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	275	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
267	override the flags completely if it is found in the environment. This is	276	override the flags completely if it is found in the environment. This is
268	useful to try out specific backends to test their performance, or to work	277	useful to try out specific backends to test their performance, or to work
269	around bugs.	278	around bugs.
270		279
		280	=item C<EVFLAG_FORKCHECK>
		281
		282	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		283	a fork, you can also make libev check for a fork in each iteration by
		284	enabling this flag.
		285
		286	This works by calling C<getpid ()> on every iteration of the loop,
		287	and thus this might slow down your event loop if you do a lot of loop
		288	iterations and little real work, but is usually not noticeable (on my
		289	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		290	without a syscall and thus I<very> fast, but my Linux system also has
		291	C<pthread_atfork> which is even faster).
		292
		293	The big advantage of this flag is that you can forget about fork (and
		294	forget about forgetting to tell libev about forking) when you use this
		295	flag.
		296
		297	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		298	environment variable.
		299
271	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	300	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
272		301
273	This is your standard select(2) backend. Not I<completely> standard, as	302	This is your standard select(2) backend. Not I<completely> standard, as
274	libev tries to roll its own fd_set with no limits on the number of fds,	303	libev tries to roll its own fd_set with no limits on the number of fds,
275	but if that fails, expect a fairly low limit on the number of fds when	304	but if that fails, expect a fairly low limit on the number of fds when
…		…
302		331
303	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	332	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
304		333
305	Kqueue deserves special mention, as at the time of this writing, it	334	Kqueue deserves special mention, as at the time of this writing, it
306	was broken on all BSDs except NetBSD (usually it doesn't work with	335	was broken on all BSDs except NetBSD (usually it doesn't work with
307	anything but sockets and pipes, except on Darwin, where of course its	336	anything but sockets and pipes, except on Darwin, where of course it's
308	completely useless). For this reason its not being "autodetected"	337	completely useless). For this reason it's not being "autodetected"
309	unless you explicitly specify it explicitly in the flags (i.e. using	338	unless you explicitly specify it explicitly in the flags (i.e. using
310	C<EVBACKEND_KQUEUE>).	339	C<EVBACKEND_KQUEUE>).
311		340
312	It scales in the same way as the epoll backend, but the interface to the	341	It scales in the same way as the epoll backend, but the interface to the
313	kernel is more efficient (which says nothing about its actual speed, of	342	kernel is more efficient (which says nothing about its actual speed, of
…		…
375	Destroys the default loop again (frees all memory and kernel state	404	Destroys the default loop again (frees all memory and kernel state
376	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
377	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
378	responsibility to either stop all watchers cleanly yoursef I<before>	407	responsibility to either stop all watchers cleanly yoursef I<before>
379	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
380	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
381	for example).	410	for example).
		411
		412	Note 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>).
382		420
383	=item ev_loop_destroy (loop)	421	=item ev_loop_destroy (loop)
384		422
385	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
386	earlier call to C<ev_loop_new>.	424	earlier call to C<ev_loop_new>.
…		…
410		448
411	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
412	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
413	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.
414		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.
		462
415	=item unsigned int ev_backend (loop)	463	=item unsigned int ev_backend (loop)
416		464
417	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
418	use.	466	use.
419		467
…		…
421		469
422	Returns the current "event loop time", which is the time the event loop	470	Returns the current "event loop time", which is the time the event loop
423	received events and started processing them. This timestamp does not	471	received events and started processing them. This timestamp does not
424	change as long as callbacks are being processed, and this is also the base	472	change as long as callbacks are being processed, and this is also the base
425	time used for relative timers. You can treat it as the timestamp of the	473	time used for relative timers. You can treat it as the timestamp of the
426	event occuring (or more correctly, libev finding out about it).	474	event occurring (or more correctly, libev finding out about it).
427		475
428	=item ev_loop (loop, int flags)	476	=item ev_loop (loop, int flags)
429		477
430	Finally, this is it, the event handler. This function usually is called	478	Finally, this is it, the event handler. This function usually is called
431	after you initialised all your watchers and you want to start handling	479	after you initialised all your watchers and you want to start handling
…		…
452	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
453	usually a better approach for this kind of thing.	501	usually a better approach for this kind of thing.
454		502
455	Here are the gory details of what C<ev_loop> does:	503	Here are the gory details of what C<ev_loop> does:
456		504
		505	- Before the first iteration, call any pending watchers.
457	* If there are no active watchers (reference count is zero), return.	506	* If there are no active watchers (reference count is zero), return.
458	- Queue prepare watchers and then call all outstanding watchers.	507	- Queue all prepare watchers and then call all outstanding watchers.
459	- If we have been forked, recreate the kernel state.	508	- If we have been forked, recreate the kernel state.
460	- Update the kernel state with all outstanding changes.	509	- Update the kernel state with all outstanding changes.
461	- Update the "event loop time".	510	- Update the "event loop time".
462	- Calculate for how long to block.	511	- Calculate for how long to block.
463	- Block the process, waiting for any events.	512	- Block the process, waiting for any events.
…		…
702	=item bool ev_is_pending (ev_TYPE *watcher)	751	=item bool ev_is_pending (ev_TYPE *watcher)
703		752
704	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
705	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
706	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
707	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
708	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).
709		759
710	=item callback ev_cb (ev_TYPE *watcher)	760	=item callback ev_cb (ev_TYPE *watcher)
711		761
712	Returns the callback currently set on the watcher.	762	Returns the callback currently set on the watcher.
713		763
714	=item ev_cb_set (ev_TYPE *watcher, callback)	764	=item ev_cb_set (ev_TYPE *watcher, callback)
715		765
716	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
717	(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>.
718		808
719	=back	809	=back
720		810
721		811
722	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	812	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
828	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
829	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.
830		920
831	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
832	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
833	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
834	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
835	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
836		950
837	=over 4	951	=over 4
838		952
839	=item ev_io_init (ev_io *, callback, int fd, int events)	953	=item ev_io_init (ev_io *, callback, int fd, int events)
840		954
…		…
894		1008
895	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,
896	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
897	order of execution is undefined.	1011	order of execution is undefined.
898		1012
		1013	=head3 Watcher-Specific Functions and Data Members
		1014
899	=over 4	1015	=over 4
900		1016
901	=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)
902		1018
903	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1019	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
916	=item ev_timer_again (loop)	1032	=item ev_timer_again (loop)
917		1033
918	This will act as if the timer timed out and restart it again if it is	1034	This will act as if the timer timed out and restart it again if it is
919	repeating. The exact semantics are:	1035	repeating. The exact semantics are:
920		1036
		1037	If the timer is pending, its pending status is cleared.
		1038
921	If the timer is started but nonrepeating, stop it.	1039	If the timer is started but nonrepeating, stop it (as if it timed out).
922		1040
923	If the timer is repeating, either start it if necessary (with the repeat	1041	If the timer is repeating, either start it if necessary (with the
924	value), or reset the running timer to the repeat value.	1042	C<repeat> value), or reset the running timer to the C<repeat> value.
925		1043
926	This sounds a bit complicated, but here is a useful and typical	1044	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	1045	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,	1046	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	1047	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	1048	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	1049	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	1050	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	1051	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
934	need be.	1052	automatically restart it if need be.
935		1053
936	You can also ignore the C<after> value and C<ev_timer_start> altogether	1054	That means you can ignore the C<after> value and C<ev_timer_start>
937	and only ever use the C<repeat> value:	1055	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
938		1056
939	ev_timer_init (timer, callback, 0., 5.);	1057	ev_timer_init (timer, callback, 0., 5.);
940	ev_timer_again (loop, timer);	1058	ev_timer_again (loop, timer);
941	...	1059	...
942	timer->again = 17.;	1060	timer->again = 17.;
943	ev_timer_again (loop, timer);	1061	ev_timer_again (loop, timer);
944	...	1062	...
945	timer->again = 10.;	1063	timer->again = 10.;
946	ev_timer_again (loop, timer);	1064	ev_timer_again (loop, timer);
947		1065
948	This is more efficient then stopping/starting the timer eahc time you want	1066	This is more slightly efficient then stopping/starting the timer each time
949	to modify its timeout value.	1067	you want to modify its timeout value.
950		1068
951	=item ev_tstamp repeat [read-write]	1069	=item ev_tstamp repeat [read-write]
952		1070
953	The current C<repeat> value. Will be used each time the watcher times out	1071	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),	1072	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	1114	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	1115	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 ()	1116	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	1117	+ 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	1118	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	1119	roughly 10 seconds later).
1002	again).
1003		1120
1004	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
1005	triggering an event on eahc midnight, local time.	1122	triggering an event on each midnight, local time or other, complicated,
		1123	rules.
1006		1124
1007	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
1008	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
1009	during the same loop iteration then order of execution is undefined.	1127	during the same loop iteration then order of execution is undefined.
1010		1128
		1129	=head3 Watcher-Specific Functions and Data Members
		1130
1011	=over 4	1131	=over 4
1012		1132
1013	=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)
1014		1134
1015	=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)
…		…
1017	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
1018	operation, and we will explain them from simplest to complex:	1138	operation, and we will explain them from simplest to complex:
1019		1139
1020	=over 4	1140	=over 4
1021		1141
1022	=item * absolute timer (interval = reschedule_cb = 0)	1142	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1023		1143
1024	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
1025	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,
1026	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
1027	system time reaches or surpasses this time.	1147	system time reaches or surpasses this time.
1028		1148
1029	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1149	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1030		1150
1031	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
1032	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)
1033	of any time jumps.	1153	and then repeat, regardless of any time jumps.
1034		1154
1035	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
1036	time:	1156	time:
1037		1157
1038	ev_periodic_set (&periodic, 0., 3600., 0);	1158	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1044		1164
1045	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
1046	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
1047	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.
1048		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
1049	=item * manual reschedule mode (reschedule_cb = callback)	1173	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1050		1174
1051	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
1052	ignored. Instead, each time the periodic watcher gets scheduled, the	1176	ignored. Instead, each time the periodic watcher gets scheduled, the
1053	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
1054	current time as second argument.	1178	current time as second argument.
1055		1179
1056	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,
1057	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,
1058	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
1059	starting a prepare watcher).	1183	starting an C<ev_prepare> watcher, which is legal).
1060		1184
1061	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,
1062	ev_tstamp now)>, e.g.:	1186	ev_tstamp now)>, e.g.:
1063		1187
1064	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)
…		…
1087	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
1088	when you changed some parameters or the reschedule callback would return	1212	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	1213	a different time than the last time it was called (e.g. in a crond like
1090	program when the crontabs have changed).	1214	program when the crontabs have changed).
1091		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
1092	=item ev_tstamp interval [read-write]	1224	=item ev_tstamp interval [read-write]
1093		1225
1094	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
1095	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
1096	called.	1228	called.
…		…
1098	=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]
1099		1231
1100	The current reschedule callback, or C<0>, if this functionality is	1232	The current reschedule callback, or C<0>, if this functionality is
1101	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
1102	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.
1103		1240
1104	=back	1241	=back
1105		1242
1106	Example: Call a callback every hour, or, more precisely, whenever the	1243	Example: Call a callback every hour, or, more precisely, whenever the
1107	system clock is divisible by 3600. The callback invocation times have	1244	system clock is divisible by 3600. The callback invocation times have
…		…
1149	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
1150	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
1151	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
1152	SIG_DFL (regardless of what it was set to before).	1289	SIG_DFL (regardless of what it was set to before).
1153		1290
		1291	=head3 Watcher-Specific Functions and Data Members
		1292
1154	=over 4	1293	=over 4
1155		1294
1156	=item ev_signal_init (ev_signal *, callback, int signum)	1295	=item ev_signal_init (ev_signal *, callback, int signum)
1157		1296
1158	=item ev_signal_set (ev_signal *, int signum)	1297	=item ev_signal_set (ev_signal *, int signum)
…		…
1169		1308
1170	=head2 C<ev_child> - watch out for process status changes	1309	=head2 C<ev_child> - watch out for process status changes
1171		1310
1172	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
1173	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
1174		1315
1175	=over 4	1316	=over 4
1176		1317
1177	=item ev_child_init (ev_child *, callback, int pid)	1318	=item ev_child_init (ev_child *, callback, int pid)
1178		1319
…		…
1222	The path does not need to exist: changing from "path exists" to "path does	1363	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	1364	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	1365	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	1366	otherwise always forced to be at least one) and all the other fields of
1226	the stat buffer having unspecified contents.	1367	the stat buffer having unspecified contents.
		1368
		1369	The path I<should> be absolute and I<must not> end in a slash. If it is
		1370	relative and your working directory changes, the behaviour is undefined.
1227		1371
1228	Since there is no standard to do this, the portable implementation simply	1372	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	1373	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	1374	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,	1375	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	1387	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	1388	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	1389	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	1390	usually detected immediately, and if the file exists there will be no
1247	polling.	1391	polling.
		1392
		1393	=head3 Watcher-Specific Functions and Data Members
1248		1394
1249	=over 4	1395	=over 4
1250		1396
1251	=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)
1252		1398
…		…
1316	ev_stat_start (loop, &passwd);	1462	ev_stat_start (loop, &passwd);
1317		1463
1318		1464
1319	=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...
1320		1466
1321	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
1322	(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
1323	as your process is busy handling sockets or timeouts (or even signals,	1469	count).
1324	imagine) it will not be triggered. But when your process is idle all idle	1470
1325	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
1326	until stopped, that is, or your process receives more events and becomes	1475	iteration - until stopped, that is, or your process receives more events
1327	busy.	1476	and becomes busy again with higher priority stuff.
1328		1477
1329	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
1330	active, the process will not block when waiting for new events.	1479	active, the process will not block when waiting for new events.
1331		1480
1332	Apart from keeping your process non-blocking (which is a useful	1481	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	1482	effect on its own sometimes), idle watchers are a good place to do
1334	"pseudo-background processing", or delay processing stuff to after the	1483	"pseudo-background processing", or delay processing stuff to after the
1335	event loop has handled all outstanding events.	1484	event loop has handled all outstanding events.
		1485
		1486	=head3 Watcher-Specific Functions and Data Members
1336		1487
1337	=over 4	1488	=over 4
1338		1489
1339	=item ev_idle_init (ev_signal *, callback)	1490	=item ev_idle_init (ev_signal *, callback)
1340		1491
…		…
1398	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
1399	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
1400	loop from blocking if lower-priority coroutines are active, thus mapping	1551	loop from blocking if lower-priority coroutines are active, thus mapping
1401	low-priority coroutines to idle/background tasks).	1552	low-priority coroutines to idle/background tasks).
1402		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
1403	=over 4	1566	=over 4
1404		1567
1405	=item ev_prepare_init (ev_prepare *, callback)	1568	=item ev_prepare_init (ev_prepare *, callback)
1406		1569
1407	=item ev_check_init (ev_check *, callback)	1570	=item ev_check_init (ev_check *, callback)
…		…
1410	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>
1411	macros, but using them is utterly, utterly and completely pointless.	1574	macros, but using them is utterly, utterly and completely pointless.
1412		1575
1413	=back	1576	=back
1414		1577
1415	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
1416	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,
1417	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
1418	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.
1419		1590
1420	static ev_io iow [nfd];	1591	static ev_io iow [nfd];
1421	static ev_timer tw;	1592	static ev_timer tw;
1422		1593
1423	static void	1594	static void
1424	io_cb (ev_loop loop, ev_io w, int revents)	1595	io_cb (ev_loop loop, ev_io w, int revents)
1425	{	1596	{
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	}	1597	}
1432		1598
1433	// create io watchers for each fd and a timer before blocking	1599	// create io watchers for each fd and a timer before blocking
1434	static void	1600	static void
1435	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1601	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1436	{	1602	{
1437	int timeout = 3600000;truct pollfd fds [nfd];	1603	int timeout = 3600000;
		1604	struct pollfd fds [nfd];
1438	// actual code will need to loop here and realloc etc.	1605	// actual code will need to loop here and realloc etc.
1439	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1606	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1440		1607
1441	/* 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 */
1442	ev_timer_init (&tw, 0, timeout * 1e-3);	1609	ev_timer_init (&tw, 0, timeout * 1e-3);
1443	ev_timer_start (loop, &tw);	1610	ev_timer_start (loop, &tw);
1444		1611
1445	// create on ev_io per pollfd	1612	// create one ev_io per pollfd
1446	for (int i = 0; i < nfd; ++i)	1613	for (int i = 0; i < nfd; ++i)
1447	{	1614	{
1448	ev_io_init (iow + i, io_cb, fds [i].fd,	1615	ev_io_init (iow + i, io_cb, fds [i].fd,
1449	((fds [i].events & POLLIN ? EV_READ : 0)	1616	((fds [i].events & POLLIN ? EV_READ : 0)
1450	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1617	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1451		1618
1452	fds [i].revents = 0;	1619	fds [i].revents = 0;
1453	iow [i].data = fds + i;
1454	ev_io_start (loop, iow + i);	1620	ev_io_start (loop, iow + i);
1455	}	1621	}
1456	}	1622	}
1457		1623
1458	// stop all watchers after blocking	1624	// stop all watchers after blocking
…		…
1460	adns_check_cb (ev_loop loop, ev_check w, int revents)	1626	adns_check_cb (ev_loop loop, ev_check w, int revents)
1461	{	1627	{
1462	ev_timer_stop (loop, &tw);	1628	ev_timer_stop (loop, &tw);
1463		1629
1464	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
1465	ev_io_stop (loop, iow + i);	1640	ev_io_stop (loop, iow + i);
		1641	}
1466		1642
1467	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;
1468	}	1703	}
1469		1704
1470		1705
1471	=head2 C<ev_embed> - when one backend isn't enough...	1706	=head2 C<ev_embed> - when one backend isn't enough...
1472		1707
…		…
1536	ev_embed_start (loop_hi, &embed);	1771	ev_embed_start (loop_hi, &embed);
1537	}	1772	}
1538	else	1773	else
1539	loop_lo = loop_hi;	1774	loop_lo = loop_hi;
1540		1775
		1776	=head3 Watcher-Specific Functions and Data Members
		1777
1541	=over 4	1778	=over 4
1542		1779
1543	=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)
1544		1781
1545	=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)
…		…
1554		1791
1555	Make a single, non-blocking sweep over the embedded loop. This works	1792	Make a single, non-blocking sweep over the embedded loop. This works
1556	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1793	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1557	apropriate way for embedded loops.	1794	apropriate way for embedded loops.
1558		1795
1559	=item struct ev_loop *loop [read-only]	1796	=item struct ev_loop *other [read-only]
1560		1797
1561	The embedded event loop.	1798	The embedded event loop.
1562		1799
1563	=back	1800	=back
1564		1801
…		…
1571	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,
1572	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
1573	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
1574	handlers will be invoked, too, of course.	1811	handlers will be invoked, too, of course.
1575		1812
		1813	=head3 Watcher-Specific Functions and Data Members
		1814
1576	=over 4	1815	=over 4
1577		1816
1578	=item ev_fork_init (ev_signal *, callback)	1817	=item ev_fork_init (ev_signal *, callback)
1579		1818
1580	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
…		…
1676		1915
1677	To use it,	1916	To use it,
1678		1917
1679	#include <ev++.h>	1918	#include <ev++.h>
1680		1919
1681	(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
1682	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
1683	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>.
1684		1924
1685	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++
1686	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).
1687		1935
1688	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:
1689		1937
1690	=over 4	1938	=over 4
1691		1939
…		…
1707		1955
1708	All of those classes have these methods:	1956	All of those classes have these methods:
1709		1957
1710	=over 4	1958	=over 4
1711		1959
1712	=item ev::TYPE::TYPE (object , object::method )	1960	=item ev::TYPE::TYPE ()
1713		1961
1714	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1962	=item ev::TYPE::TYPE (struct ev_loop *)
1715		1963
1716	=item ev::TYPE::~TYPE	1964	=item ev::TYPE::~TYPE
1717		1965
1718	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
1719	the event handler callback to call in this class. The constructor calls	1967	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	1968
1721	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
1722	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).
1723		1977
1724	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> ();
1725		2018
1726	=item w->set (struct ev_loop *)	2019	=item w->set (struct ev_loop *)
1727		2020
1728	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
1729	do this when the watcher is inactive (and not pending either).	2022	do this when the watcher is inactive (and not pending either).
1730		2023
1731	=item w->set ([args])	2024	=item w->set ([args])
1732		2025
1733	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
1734	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
1735	automatically stopped and restarted.	2028	automatically stopped and restarted when reconfiguring it with this
		2029	method.
1736		2030
1737	=item w->start ()	2031	=item w->start ()
1738		2032
1739	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
1740	constructor already takes the loop.	2034	constructor already stores the event loop.
1741		2035
1742	=item w->stop ()	2036	=item w->stop ()
1743		2037
1744	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.
1745		2039
1746	=item w->again () C<ev::timer>, C<ev::periodic> only	2040	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1747		2041
1748	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
1749	C<ev_TYPE_again> function.	2043	C<ev_TYPE_again> function.
1750		2044
1751	=item w->sweep () C<ev::embed> only	2045	=item w->sweep () (C<ev::embed> only)
1752		2046
1753	Invokes C<ev_embed_sweep>.	2047	Invokes C<ev_embed_sweep>.
1754		2048
1755	=item w->update () C<ev::stat> only	2049	=item w->update () (C<ev::stat> only)
1756		2050
1757	Invokes C<ev_stat_stat>.	2051	Invokes C<ev_stat_stat>.
1758		2052
1759	=back	2053	=back
1760		2054
…		…
1770		2064
1771	myclass ();	2065	myclass ();
1772	}	2066	}
1773		2067
1774	myclass::myclass (int fd)	2068	myclass::myclass (int fd)
1775	: io (this, &myclass::io_cb),
1776	idle (this, &myclass::idle_cb)
1777	{	2069	{
		2070	io .set <myclass, &myclass::io_cb > (this);
		2071	idle.set <myclass, &myclass::idle_cb> (this);
		2072
1778	io.start (fd, ev::READ);	2073	io.start (fd, ev::READ);
1779	}	2074	}
1780		2075
1781		2076
1782	=head1 MACRO MAGIC	2077	=head1 MACRO MAGIC
1783		2078
1784	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
1785	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2080	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1786	callbacks have an initial C<struct ev_loop *> argument.	2081	functions and callbacks have an initial C<struct ev_loop *> argument.
1787		2082
1788	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
1789	following macros are defined:	2084	following macros are defined:
1790		2085
1791	=over 4	2086	=over 4
…		…
1823	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
1824	loop, if multiple loops are supported ("ev loop default").	2119	loop, if multiple loops are supported ("ev loop default").
1825		2120
1826	=back	2121	=back
1827		2122
1828	Example: Declare and initialise a check watcher, working regardless of	2123	Example: Declare and initialise a check watcher, utilising the above
1829	wether multiple loops are supported or not.	2124	macros so it will work regardless of whether multiple loops are supported
		2125	or not.
1830		2126
1831	static void	2127	static void
1832	check_cb (EV_P_ ev_timer *w, int revents)	2128	check_cb (EV_P_ ev_timer *w, int revents)
1833	{	2129	{
1834	ev_check_stop (EV_A_ w);	2130	ev_check_stop (EV_A_ w);
…		…
1837	ev_check check;	2133	ev_check check;
1838	ev_check_init (&check, check_cb);	2134	ev_check_init (&check, check_cb);
1839	ev_check_start (EV_DEFAULT_ &check);	2135	ev_check_start (EV_DEFAULT_ &check);
1840	ev_loop (EV_DEFAULT_ 0);	2136	ev_loop (EV_DEFAULT_ 0);
1841		2137
1842
1843	=head1 EMBEDDING	2138	=head1 EMBEDDING
1844		2139
1845	Libev can (and often is) directly embedded into host	2140	Libev can (and often is) directly embedded into host
1846	applications. Examples of applications that embed it include the Deliantra	2141	applications. Examples of applications that embed it include the Deliantra
1847	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2142	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1848	and rxvt-unicode.	2143	and rxvt-unicode.
1849		2144
1850	The goal is to enable you to just copy the neecssary files into your	2145	The goal is to enable you to just copy the necessary files into your
1851	source directory without having to change even a single line in them, so	2146	source directory without having to change even a single line in them, so
1852	you can easily upgrade by simply copying (or having a checked-out copy of	2147	you can easily upgrade by simply copying (or having a checked-out copy of
1853	libev somewhere in your source tree).	2148	libev somewhere in your source tree).
1854		2149
1855	=head2 FILESETS	2150	=head2 FILESETS
…		…
1886	ev_vars.h	2181	ev_vars.h
1887	ev_wrap.h	2182	ev_wrap.h
1888		2183
1889	ev_win32.c required on win32 platforms only	2184	ev_win32.c required on win32 platforms only
1890		2185
1891	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)
1892	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)
1893	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)
1894	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)
1895	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)
1896		2191
…		…
1945		2240
1946	If defined to be C<1>, libev will try to detect the availability of the	2241	If defined to be C<1>, libev will try to detect the availability of the
1947	monotonic clock option at both compiletime and runtime. Otherwise no use	2242	monotonic clock option at both compiletime and runtime. Otherwise no use
1948	of the monotonic clock option will be attempted. If you enable this, you	2243	of the monotonic clock option will be attempted. If you enable this, you
1949	usually have to link against librt or something similar. Enabling it when	2244	usually have to link against librt or something similar. Enabling it when
1950	the functionality isn't available is safe, though, althoguh you have	2245	the functionality isn't available is safe, though, although you have
1951	to make sure you link against any libraries where the C<clock_gettime>	2246	to make sure you link against any libraries where the C<clock_gettime>
1952	function is hiding in (often F<-lrt>).	2247	function is hiding in (often F<-lrt>).
1953		2248
1954	=item EV_USE_REALTIME	2249	=item EV_USE_REALTIME
1955		2250
1956	If defined to be C<1>, libev will try to detect the availability of the	2251	If defined to be C<1>, libev will try to detect the availability of the
1957	realtime clock option at compiletime (and assume its availability at	2252	realtime clock option at compiletime (and assume its availability at
1958	runtime if successful). Otherwise no use of the realtime clock option will	2253	runtime if successful). Otherwise no use of the realtime clock option will
1959	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2254	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
1960	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2255	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
1961	in the description of C<EV_USE_MONOTONIC>, though.	2256	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
1962		2257
1963	=item EV_USE_SELECT	2258	=item EV_USE_SELECT
1964		2259
1965	If undefined or defined to be C<1>, libev will compile in support for the	2260	If undefined or defined to be C<1>, libev will compile in support for the
1966	C<select>(2) backend. No attempt at autodetection will be done: if no	2261	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
2059	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
2060	additional independent event loops. Otherwise there will be no support	2355	additional independent event loops. Otherwise there will be no support
2061	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
2062	argument. Instead, all functions act on the single default loop.	2357	argument. Instead, all functions act on the single default loop.
2063		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
2064	=item EV_PERIODIC_ENABLE	2376	=item EV_PERIODIC_ENABLE
2065		2377
2066	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
2067	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
2068	code.	2386	code.
2069		2387
2070	=item EV_EMBED_ENABLE	2388	=item EV_EMBED_ENABLE
2071		2389
…		…
2122		2440
2123	=item ev_set_cb (ev, cb)	2441	=item ev_set_cb (ev, cb)
2124		2442
2125	Can be used to change the callback member declaration in each watcher,	2443	Can be used to change the callback member declaration in each watcher,
2126	and the way callbacks are invoked and set. Must expand to a struct member	2444	and the way callbacks are invoked and set. Must expand to a struct member
2127	definition and a statement, respectively. See the F<ev.v> header file for	2445	definition and a statement, respectively. See the F<ev.c> header file for
2128	their default definitions. One possible use for overriding these is to	2446	their default definitions. One possible use for overriding these is to
2129	avoid the C<struct ev_loop *> as first argument in all cases, or to use	2447	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2130	method calls instead of plain function calls in C++.	2448	method calls instead of plain function calls in C++.
		2449
		2450	=head2 EXPORTED API SYMBOLS
		2451
		2452	If you need to re-export the API (e.g. via a dll) and you need a list of
		2453	exported symbols, you can use the provided F<Symbol.*> files which list
		2454	all public symbols, one per line:
		2455
		2456	Symbols.ev for libev proper
		2457	Symbols.event for the libevent emulation
		2458
		2459	This can also be used to rename all public symbols to avoid clashes with
		2460	multiple versions of libev linked together (which is obviously bad in
		2461	itself, but sometimes it is inconvinient to avoid this).
		2462
		2463	A sed command like this will create wrapper C<#define>'s that you need to
		2464	include before including F<ev.h>:
		2465
		2466	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2467
		2468	This would create a file F<wrap.h> which essentially looks like this:
		2469
		2470	#define ev_backend myprefix_ev_backend
		2471	#define ev_check_start myprefix_ev_check_start
		2472	#define ev_check_stop myprefix_ev_check_stop
		2473	...
2131		2474
2132	=head2 EXAMPLES	2475	=head2 EXAMPLES
2133		2476
2134	For a real-world example of a program the includes libev	2477	For a real-world example of a program the includes libev
2135	verbatim, you can have a look at the EV perl module	2478	verbatim, you can have a look at the EV perl module
…		…
2138	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2481	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	2482	will be compiled. It is pretty complex because it provides its own header
2140	file.	2483	file.
2141		2484
2142	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2485	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:	2486	that everybody includes and which overrides some configure choices:
2144		2487
		2488	#define EV_MINIMAL 1
2145	#define EV_USE_POLL 0	2489	#define EV_USE_POLL 0
2146	#define EV_MULTIPLICITY 0	2490	#define EV_MULTIPLICITY 0
2147	#define EV_PERIODICS 0	2491	#define EV_PERIODIC_ENABLE 0
		2492	#define EV_STAT_ENABLE 0
		2493	#define EV_FORK_ENABLE 0
2148	#define EV_CONFIG_H <config.h>	2494	#define EV_CONFIG_H <config.h>
		2495	#define EV_MINPRI 0
		2496	#define EV_MAXPRI 0
2149		2497
2150	#include "ev++.h"	2498	#include "ev++.h"
2151		2499
2152	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2500	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2153		2501
…		…
2159		2507
2160	In this section the complexities of (many of) the algorithms used inside	2508	In this section the complexities of (many of) the algorithms used inside
2161	libev will be explained. For complexity discussions about backends see the	2509	libev will be explained. For complexity discussions about backends see the
2162	documentation for C<ev_default_init>.	2510	documentation for C<ev_default_init>.
2163		2511
		2512	All of the following are about amortised time: If an array needs to be
		2513	extended, libev needs to realloc and move the whole array, but this
		2514	happens asymptotically never with higher number of elements, so O(1) might
		2515	mean it might do a lengthy realloc operation in rare cases, but on average
		2516	it is much faster and asymptotically approaches constant time.
		2517
2164	=over 4	2518	=over 4
2165		2519
2166	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2520	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2167		2521
		2522	This means that, when you have a watcher that triggers in one hour and
		2523	there are 100 watchers that would trigger before that then inserting will
		2524	have to skip those 100 watchers.
		2525
2168	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2526	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2169		2527
		2528	That means that for changing a timer costs less than removing/adding them
		2529	as only the relative motion in the event queue has to be paid for.
		2530
2170	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2531	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2171		2532
		2533	These just add the watcher into an array or at the head of a list.
2172	=item Stopping check/prepare/idle watchers: O(1)	2534	=item Stopping check/prepare/idle watchers: O(1)
2173		2535
2174	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2536	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2175		2537
		2538	These watchers are stored in lists then need to be walked to find the
		2539	correct watcher to remove. The lists are usually short (you don't usually
		2540	have many watchers waiting for the same fd or signal).
		2541
2176	=item Finding the next timer per loop iteration: O(1)	2542	=item Finding the next timer per loop iteration: O(1)
2177		2543
2178	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2544	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2179		2545
		2546	A change means an I/O watcher gets started or stopped, which requires
		2547	libev to recalculate its status (and possibly tell the kernel).
		2548
2180	=item Activating one watcher: O(1)	2549	=item Activating one watcher: O(1)
2181		2550
		2551	=item Priority handling: O(number_of_priorities)
		2552
		2553	Priorities are implemented by allocating some space for each
		2554	priority. When doing priority-based operations, libev usually has to
		2555	linearly search all the priorities.
		2556
2182	=back	2557	=back
2183		2558
2184		2559
2185	=head1 AUTHOR	2560	=head1 AUTHOR
2186		2561

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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 1.92 by root, Fri Dec 21 01:26:04 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 1.92 by root, Fri Dec 21 01:26:04 2007 UTC