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

Comparing libev/ev.pod (file contents):
Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC vs.
Revision 1.93 by root, Fri Dec 21 01:29:34 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.
…		…
163	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	172	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
164	recommended ones.	173	recommended ones.
165		174
166	See the description of C<ev_embed> watchers for more info.	175	See the description of C<ev_embed> watchers for more info.
167		176
168	=item ev_set_allocator (void (cb)(void *ptr, size_t size))	177	=item ev_set_allocator (void (cb)(void *ptr, long size))
169		178
170	Sets the allocation function to use (the prototype and semantics are	179	Sets the allocation function to use (the prototype is similar - the
171	identical to the realloc C function). It is used to allocate and free	180	semantics is identical - to the realloc C function). It is used to
172	memory (no surprises here). If it returns zero when memory needs to be	181	allocate and free memory (no surprises here). If it returns zero when
173	allocated, the library might abort or take some potentially destructive	182	memory needs to be allocated, the library might abort or take some
174	action. The default is your system realloc function.	183	potentially destructive action. The default is your system realloc
		184	function.
175		185
176	You could override this function in high-availability programs to, say,	186	You could override this function in high-availability programs to, say,
177	free some memory if it cannot allocate memory, to use a special allocator,	187	free some memory if it cannot allocate memory, to use a special allocator,
178	or even to sleep a while and retry until some memory is available.	188	or even to sleep a while and retry until some memory is available.
179		189
…		…
265	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	275	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
266	override the flags completely if it is found in the environment. This is	276	override the flags completely if it is found in the environment. This is
267	useful to try out specific backends to test their performance, or to work	277	useful to try out specific backends to test their performance, or to work
268	around bugs.	278	around bugs.
269		279
		280	=item C<EVFLAG_FORKCHECK>
		281
		282	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		283	a fork, you can also make libev check for a fork in each iteration by
		284	enabling this flag.
		285
		286	This works by calling C<getpid ()> on every iteration of the loop,
		287	and thus this might slow down your event loop if you do a lot of loop
		288	iterations and little real work, but is usually not noticeable (on my
		289	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		290	without a syscall and thus I<very> fast, but my Linux system also has
		291	C<pthread_atfork> which is even faster).
		292
		293	The big advantage of this flag is that you can forget about fork (and
		294	forget about forgetting to tell libev about forking) when you use this
		295	flag.
		296
		297	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		298	environment variable.
		299
270	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	300	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
271		301
272	This is your standard select(2) backend. Not I<completely> standard, as	302	This is your standard select(2) backend. Not I<completely> standard, as
273	libev tries to roll its own fd_set with no limits on the number of fds,	303	libev tries to roll its own fd_set with no limits on the number of fds,
274	but if that fails, expect a fairly low limit on the number of fds when	304	but if that fails, expect a fairly low limit on the number of fds when
…		…
301		331
302	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	332	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
303		333
304	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
305	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
306	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
307	completely useless). For this reason its not being "autodetected"	337	completely useless). For this reason it's not being "autodetected"
308	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
309	C<EVBACKEND_KQUEUE>).	339	C<EVBACKEND_KQUEUE>).
310		340
311	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
312	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
…		…
374	Destroys the default loop again (frees all memory and kernel state	404	Destroys the default loop again (frees all memory and kernel state
375	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
376	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
377	responsibility to either stop all watchers cleanly yoursef I<before>	407	responsibility to either stop all watchers cleanly yoursef I<before>
378	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
379	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
380	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>).
381		420
382	=item ev_loop_destroy (loop)	421	=item ev_loop_destroy (loop)
383		422
384	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
385	earlier call to C<ev_loop_new>.	424	earlier call to C<ev_loop_new>.
…		…
409		448
410	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
411	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
412	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.
413		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
414	=item unsigned int ev_backend (loop)	463	=item unsigned int ev_backend (loop)
415		464
416	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
417	use.	466	use.
418		467
…		…
420		469
421	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
422	received events and started processing them. This timestamp does not	471	received events and started processing them. This timestamp does not
423	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
424	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
425	event occuring (or more correctly, libev finding out about it).	474	event occurring (or more correctly, libev finding out about it).
426		475
427	=item ev_loop (loop, int flags)	476	=item ev_loop (loop, int flags)
428		477
429	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
430	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
…		…
451	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
452	usually a better approach for this kind of thing.	501	usually a better approach for this kind of thing.
453		502
454	Here are the gory details of what C<ev_loop> does:	503	Here are the gory details of what C<ev_loop> does:
455		504
		505	- Before the first iteration, call any pending watchers.
456	* If there are no active watchers (reference count is zero), return.	506	* If there are no active watchers (reference count is zero), return.
457	- Queue prepare watchers and then call all outstanding watchers.	507	- Queue all prepare watchers and then call all outstanding watchers.
458	- If we have been forked, recreate the kernel state.	508	- If we have been forked, recreate the kernel state.
459	- Update the kernel state with all outstanding changes.	509	- Update the kernel state with all outstanding changes.
460	- Update the "event loop time".	510	- Update the "event loop time".
461	- Calculate for how long to block.	511	- Calculate for how long to block.
462	- Block the process, waiting for any events.	512	- Block the process, waiting for any events.
…		…
701	=item bool ev_is_pending (ev_TYPE *watcher)	751	=item bool ev_is_pending (ev_TYPE *watcher)
702		752
703	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
704	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
705	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
706	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
707	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).
708		759
709	=item callback ev_cb (ev_TYPE *watcher)	760	=item callback ev_cb (ev_TYPE *watcher)
710		761
711	Returns the callback currently set on the watcher.	762	Returns the callback currently set on the watcher.
712		763
713	=item ev_cb_set (ev_TYPE *watcher, callback)	764	=item ev_cb_set (ev_TYPE *watcher, callback)
714		765
715	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
716	(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>.
717		808
718	=back	809	=back
719		810
720		811
721	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	812	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
827	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
828	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.
829		920
830	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
831	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
832	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
833	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
834	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
835		950
836	=over 4	951	=over 4
837		952
838	=item ev_io_init (ev_io *, callback, int fd, int events)	953	=item ev_io_init (ev_io *, callback, int fd, int events)
839		954
…		…
893		1008
894	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,
895	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
896	order of execution is undefined.	1011	order of execution is undefined.
897		1012
		1013	=head3 Watcher-Specific Functions and Data Members
		1014
898	=over 4	1015	=over 4
899		1016
900	=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)
901		1018
902	=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)
…		…
915	=item ev_timer_again (loop)	1032	=item ev_timer_again (loop)
916		1033
917	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
918	repeating. The exact semantics are:	1035	repeating. The exact semantics are:
919		1036
		1037	If the timer is pending, its pending status is cleared.
		1038
920	If the timer is started but nonrepeating, stop it.	1039	If the timer is started but nonrepeating, stop it (as if it timed out).
921		1040
922	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
923	value), or reset the running timer to the repeat value.	1042	C<repeat> value), or reset the running timer to the C<repeat> value.
924		1043
925	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
926	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
927	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
928	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
929	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
930	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
931	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
932	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
933	need be.	1052	automatically restart it if need be.
934		1053
935	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>
936	and only ever use the C<repeat> value:	1055	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
937		1056
938	ev_timer_init (timer, callback, 0., 5.);	1057	ev_timer_init (timer, callback, 0., 5.);
939	ev_timer_again (loop, timer);	1058	ev_timer_again (loop, timer);
940	...	1059	...
941	timer->again = 17.;	1060	timer->again = 17.;
942	ev_timer_again (loop, timer);	1061	ev_timer_again (loop, timer);
943	...	1062	...
944	timer->again = 10.;	1063	timer->again = 10.;
945	ev_timer_again (loop, timer);	1064	ev_timer_again (loop, timer);
946		1065
947	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
948	to modify its timeout value.	1067	you want to modify its timeout value.
949		1068
950	=item ev_tstamp repeat [read-write]	1069	=item ev_tstamp repeat [read-write]
951		1070
952	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
953	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),
…		…
995	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
996	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
997	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 ()
998	+ 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
999	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
1000	roughly 10 seconds later and of course not if you reset your system time	1119	roughly 10 seconds later).
1001	again).
1002		1120
1003	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
1004	triggering an event on eahc midnight, local time.	1122	triggering an event on each midnight, local time or other, complicated,
		1123	rules.
1005		1124
1006	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
1007	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
1008	during the same loop iteration then order of execution is undefined.	1127	during the same loop iteration then order of execution is undefined.
1009		1128
		1129	=head3 Watcher-Specific Functions and Data Members
		1130
1010	=over 4	1131	=over 4
1011		1132
1012	=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)
1013		1134
1014	=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)
…		…
1016	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
1017	operation, and we will explain them from simplest to complex:	1138	operation, and we will explain them from simplest to complex:
1018		1139
1019	=over 4	1140	=over 4
1020		1141
1021	=item * absolute timer (interval = reschedule_cb = 0)	1142	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1022		1143
1023	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
1024	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,
1025	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
1026	system time reaches or surpasses this time.	1147	system time reaches or surpasses this time.
1027		1148
1028	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1149	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1029		1150
1030	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
1031	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)
1032	of any time jumps.	1153	and then repeat, regardless of any time jumps.
1033		1154
1034	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
1035	time:	1156	time:
1036		1157
1037	ev_periodic_set (&periodic, 0., 3600., 0);	1158	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1043		1164
1044	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
1045	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
1046	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.
1047		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
1048	=item * manual reschedule mode (reschedule_cb = callback)	1173	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1049		1174
1050	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
1051	ignored. Instead, each time the periodic watcher gets scheduled, the	1176	ignored. Instead, each time the periodic watcher gets scheduled, the
1052	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
1053	current time as second argument.	1178	current time as second argument.
1054		1179
1055	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,
1056	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,
1057	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
1058	starting a prepare watcher).	1183	starting an C<ev_prepare> watcher, which is legal).
1059		1184
1060	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,
1061	ev_tstamp now)>, e.g.:	1186	ev_tstamp now)>, e.g.:
1062		1187
1063	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)
…		…
1086	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
1087	when you changed some parameters or the reschedule callback would return	1212	when you changed some parameters or the reschedule callback would return
1088	a different time than the last time it was called (e.g. in a crond like	1213	a different time than the last time it was called (e.g. in a crond like
1089	program when the crontabs have changed).	1214	program when the crontabs have changed).
1090		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
1091	=item ev_tstamp interval [read-write]	1224	=item ev_tstamp interval [read-write]
1092		1225
1093	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
1094	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
1095	called.	1228	called.
…		…
1097	=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]
1098		1231
1099	The current reschedule callback, or C<0>, if this functionality is	1232	The current reschedule callback, or C<0>, if this functionality is
1100	switched off. Can be changed any time, but changes only take effect when	1233	switched off. Can be changed any time, but changes only take effect when
1101	the periodic timer fires or C<ev_periodic_again> is being called.	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.
1102		1240
1103	=back	1241	=back
1104		1242
1105	Example: Call a callback every hour, or, more precisely, whenever the	1243	Example: Call a callback every hour, or, more precisely, whenever the
1106	system clock is divisible by 3600. The callback invocation times have	1244	system clock is divisible by 3600. The callback invocation times have
…		…
1148	with the kernel (thus it coexists with your own signal handlers as long	1286	with the kernel (thus it coexists with your own signal handlers as long
1149	as you don't register any with libev). Similarly, when the last signal	1287	as you don't register any with libev). Similarly, when the last signal
1150	watcher for a signal is stopped libev will reset the signal handler to	1288	watcher for a signal is stopped libev will reset the signal handler to
1151	SIG_DFL (regardless of what it was set to before).	1289	SIG_DFL (regardless of what it was set to before).
1152		1290
		1291	=head3 Watcher-Specific Functions and Data Members
		1292
1153	=over 4	1293	=over 4
1154		1294
1155	=item ev_signal_init (ev_signal *, callback, int signum)	1295	=item ev_signal_init (ev_signal *, callback, int signum)
1156		1296
1157	=item ev_signal_set (ev_signal *, int signum)	1297	=item ev_signal_set (ev_signal *, int signum)
…		…
1168		1308
1169	=head2 C<ev_child> - watch out for process status changes	1309	=head2 C<ev_child> - watch out for process status changes
1170		1310
1171	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
1172	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
1173		1315
1174	=over 4	1316	=over 4
1175		1317
1176	=item ev_child_init (ev_child *, callback, int pid)	1318	=item ev_child_init (ev_child *, callback, int pid)
1177		1319
…		…
1221	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
1222	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
1223	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
1224	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
1225	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.
1226		1371
1227	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
1228	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
1229	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
1230	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,
…		…
1242	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
1243	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
1244	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
1245	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
1246	polling.	1391	polling.
		1392
		1393	=head3 Watcher-Specific Functions and Data Members
1247		1394
1248	=over 4	1395	=over 4
1249		1396
1250	=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)
1251		1398
…		…
1315	ev_stat_start (loop, &passwd);	1462	ev_stat_start (loop, &passwd);
1316		1463
1317		1464
1318	=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...
1319		1466
1320	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
1321	(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
1322	as your process is busy handling sockets or timeouts (or even signals,	1469	count).
1323	imagine) it will not be triggered. But when your process is idle all idle	1470
1324	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
1325	until stopped, that is, or your process receives more events and becomes	1475	iteration - until stopped, that is, or your process receives more events
1326	busy.	1476	and becomes busy again with higher priority stuff.
1327		1477
1328	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
1329	active, the process will not block when waiting for new events.	1479	active, the process will not block when waiting for new events.
1330		1480
1331	Apart from keeping your process non-blocking (which is a useful	1481	Apart from keeping your process non-blocking (which is a useful
1332	effect on its own sometimes), idle watchers are a good place to do	1482	effect on its own sometimes), idle watchers are a good place to do
1333	"pseudo-background processing", or delay processing stuff to after the	1483	"pseudo-background processing", or delay processing stuff to after the
1334	event loop has handled all outstanding events.	1484	event loop has handled all outstanding events.
		1485
		1486	=head3 Watcher-Specific Functions and Data Members
1335		1487
1336	=over 4	1488	=over 4
1337		1489
1338	=item ev_idle_init (ev_signal *, callback)	1490	=item ev_idle_init (ev_signal *, callback)
1339		1491
…		…
1397	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
1398	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
1399	loop from blocking if lower-priority coroutines are active, thus mapping	1551	loop from blocking if lower-priority coroutines are active, thus mapping
1400	low-priority coroutines to idle/background tasks).	1552	low-priority coroutines to idle/background tasks).
1401		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
1402	=over 4	1566	=over 4
1403		1567
1404	=item ev_prepare_init (ev_prepare *, callback)	1568	=item ev_prepare_init (ev_prepare *, callback)
1405		1569
1406	=item ev_check_init (ev_check *, callback)	1570	=item ev_check_init (ev_check *, callback)
…		…
1409	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>
1410	macros, but using them is utterly, utterly and completely pointless.	1574	macros, but using them is utterly, utterly and completely pointless.
1411		1575
1412	=back	1576	=back
1413		1577
1414	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
1415	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,
1416	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
1417	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.
1418		1590
1419	static ev_io iow [nfd];	1591	static ev_io iow [nfd];
1420	static ev_timer tw;	1592	static ev_timer tw;
1421		1593
1422	static void	1594	static void
1423	io_cb (ev_loop loop, ev_io w, int revents)	1595	io_cb (ev_loop loop, ev_io w, int revents)
1424	{	1596	{
1425	// set the relevant poll flags
1426	// could also call adns_processreadable etc. here
1427	struct pollfd fd = (struct pollfd )w->data;
1428	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1429	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1430	}	1597	}
1431		1598
1432	// create io watchers for each fd and a timer before blocking	1599	// create io watchers for each fd and a timer before blocking
1433	static void	1600	static void
1434	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1601	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1435	{	1602	{
1436	int timeout = 3600000;truct pollfd fds [nfd];	1603	int timeout = 3600000;
		1604	struct pollfd fds [nfd];
1437	// actual code will need to loop here and realloc etc.	1605	// actual code will need to loop here and realloc etc.
1438	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1606	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1439		1607
1440	/* 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 */
1441	ev_timer_init (&tw, 0, timeout * 1e-3);	1609	ev_timer_init (&tw, 0, timeout * 1e-3);
1442	ev_timer_start (loop, &tw);	1610	ev_timer_start (loop, &tw);
1443		1611
1444	// create on ev_io per pollfd	1612	// create one ev_io per pollfd
1445	for (int i = 0; i < nfd; ++i)	1613	for (int i = 0; i < nfd; ++i)
1446	{	1614	{
1447	ev_io_init (iow + i, io_cb, fds [i].fd,	1615	ev_io_init (iow + i, io_cb, fds [i].fd,
1448	((fds [i].events & POLLIN ? EV_READ : 0)	1616	((fds [i].events & POLLIN ? EV_READ : 0)
1449	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1617	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1450		1618
1451	fds [i].revents = 0;	1619	fds [i].revents = 0;
1452	iow [i].data = fds + i;
1453	ev_io_start (loop, iow + i);	1620	ev_io_start (loop, iow + i);
1454	}	1621	}
1455	}	1622	}
1456		1623
1457	// stop all watchers after blocking	1624	// stop all watchers after blocking
…		…
1459	adns_check_cb (ev_loop loop, ev_check w, int revents)	1626	adns_check_cb (ev_loop loop, ev_check w, int revents)
1460	{	1627	{
1461	ev_timer_stop (loop, &tw);	1628	ev_timer_stop (loop, &tw);
1462		1629
1463	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
1464	ev_io_stop (loop, iow + i);	1640	ev_io_stop (loop, iow + i);
		1641	}
1465		1642
1466	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;
1467	}	1703	}
1468		1704
1469		1705
1470	=head2 C<ev_embed> - when one backend isn't enough...	1706	=head2 C<ev_embed> - when one backend isn't enough...
1471		1707
…		…
1535	ev_embed_start (loop_hi, &embed);	1771	ev_embed_start (loop_hi, &embed);
1536	}	1772	}
1537	else	1773	else
1538	loop_lo = loop_hi;	1774	loop_lo = loop_hi;
1539		1775
		1776	=head3 Watcher-Specific Functions and Data Members
		1777
1540	=over 4	1778	=over 4
1541		1779
1542	=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)
1543		1781
1544	=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)
…		…
1553		1791
1554	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
1555	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
1556	apropriate way for embedded loops.	1794	apropriate way for embedded loops.
1557		1795
1558	=item struct ev_loop *loop [read-only]	1796	=item struct ev_loop *other [read-only]
1559		1797
1560	The embedded event loop.	1798	The embedded event loop.
1561		1799
1562	=back	1800	=back
1563		1801
…		…
1570	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,
1571	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
1572	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
1573	handlers will be invoked, too, of course.	1811	handlers will be invoked, too, of course.
1574		1812
		1813	=head3 Watcher-Specific Functions and Data Members
		1814
1575	=over 4	1815	=over 4
1576		1816
1577	=item ev_fork_init (ev_signal *, callback)	1817	=item ev_fork_init (ev_signal *, callback)
1578		1818
1579	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
…		…
1675		1915
1676	To use it,	1916	To use it,
1677		1917
1678	#include <ev++.h>	1918	#include <ev++.h>
1679		1919
1680	(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
1681	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
1682	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>.
1683		1924
1684	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++
1685	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).
1686		1935
1687	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:
1688		1937
1689	=over 4	1938	=over 4
1690		1939
…		…
1706		1955
1707	All of those classes have these methods:	1956	All of those classes have these methods:
1708		1957
1709	=over 4	1958	=over 4
1710		1959
1711	=item ev::TYPE::TYPE (object , object::method )	1960	=item ev::TYPE::TYPE ()
1712		1961
1713	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1962	=item ev::TYPE::TYPE (struct ev_loop *)
1714		1963
1715	=item ev::TYPE::~TYPE	1964	=item ev::TYPE::~TYPE
1716		1965
1717	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
1718	the event handler callback to call in this class. The constructor calls	1967	with. If it is omitted, it will use C<EV_DEFAULT>.
1719	C<ev_init> for you, which means you have to call the C<set> method	1968
1720	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
1721	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).
1722		1977
1723	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> ();
1724		2018
1725	=item w->set (struct ev_loop *)	2019	=item w->set (struct ev_loop *)
1726		2020
1727	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
1728	do this when the watcher is inactive (and not pending either).	2022	do this when the watcher is inactive (and not pending either).
1729		2023
1730	=item w->set ([args])	2024	=item w->set ([args])
1731		2025
1732	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
1733	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
1734	automatically stopped and restarted.	2028	automatically stopped and restarted when reconfiguring it with this
		2029	method.
1735		2030
1736	=item w->start ()	2031	=item w->start ()
1737		2032
1738	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
1739	constructor already takes the loop.	2034	constructor already stores the event loop.
1740		2035
1741	=item w->stop ()	2036	=item w->stop ()
1742		2037
1743	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.
1744		2039
1745	=item w->again () C<ev::timer>, C<ev::periodic> only	2040	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1746		2041
1747	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
1748	C<ev_TYPE_again> function.	2043	C<ev_TYPE_again> function.
1749		2044
1750	=item w->sweep () C<ev::embed> only	2045	=item w->sweep () (C<ev::embed> only)
1751		2046
1752	Invokes C<ev_embed_sweep>.	2047	Invokes C<ev_embed_sweep>.
1753		2048
1754	=item w->update () C<ev::stat> only	2049	=item w->update () (C<ev::stat> only)
1755		2050
1756	Invokes C<ev_stat_stat>.	2051	Invokes C<ev_stat_stat>.
1757		2052
1758	=back	2053	=back
1759		2054
…		…
1769		2064
1770	myclass ();	2065	myclass ();
1771	}	2066	}
1772		2067
1773	myclass::myclass (int fd)	2068	myclass::myclass (int fd)
1774	: io (this, &myclass::io_cb),
1775	idle (this, &myclass::idle_cb)
1776	{	2069	{
		2070	io .set <myclass, &myclass::io_cb > (this);
		2071	idle.set <myclass, &myclass::idle_cb> (this);
		2072
1777	io.start (fd, ev::READ);	2073	io.start (fd, ev::READ);
1778	}	2074	}
1779		2075
1780		2076
1781	=head1 MACRO MAGIC	2077	=head1 MACRO MAGIC
1782		2078
1783	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
1784	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2080	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1785	callbacks have an initial C<struct ev_loop *> argument.	2081	functions and callbacks have an initial C<struct ev_loop *> argument.
1786		2082
1787	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
1788	following macros are defined:	2084	following macros are defined:
1789		2085
1790	=over 4	2086	=over 4
…		…
1822	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
1823	loop, if multiple loops are supported ("ev loop default").	2119	loop, if multiple loops are supported ("ev loop default").
1824		2120
1825	=back	2121	=back
1826		2122
1827	Example: Declare and initialise a check watcher, working regardless of	2123	Example: Declare and initialise a check watcher, utilising the above
1828	wether multiple loops are supported or not.	2124	macros so it will work regardless of whether multiple loops are supported
		2125	or not.
1829		2126
1830	static void	2127	static void
1831	check_cb (EV_P_ ev_timer *w, int revents)	2128	check_cb (EV_P_ ev_timer *w, int revents)
1832	{	2129	{
1833	ev_check_stop (EV_A_ w);	2130	ev_check_stop (EV_A_ w);
…		…
1836	ev_check check;	2133	ev_check check;
1837	ev_check_init (&check, check_cb);	2134	ev_check_init (&check, check_cb);
1838	ev_check_start (EV_DEFAULT_ &check);	2135	ev_check_start (EV_DEFAULT_ &check);
1839	ev_loop (EV_DEFAULT_ 0);	2136	ev_loop (EV_DEFAULT_ 0);
1840		2137
1841
1842	=head1 EMBEDDING	2138	=head1 EMBEDDING
1843		2139
1844	Libev can (and often is) directly embedded into host	2140	Libev can (and often is) directly embedded into host
1845	applications. Examples of applications that embed it include the Deliantra	2141	applications. Examples of applications that embed it include the Deliantra
1846	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)
1847	and rxvt-unicode.	2143	and rxvt-unicode.
1848		2144
1849	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
1850	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
1851	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
1852	libev somewhere in your source tree).	2148	libev somewhere in your source tree).
1853		2149
1854	=head2 FILESETS	2150	=head2 FILESETS
…		…
1885	ev_vars.h	2181	ev_vars.h
1886	ev_wrap.h	2182	ev_wrap.h
1887		2183
1888	ev_win32.c required on win32 platforms only	2184	ev_win32.c required on win32 platforms only
1889		2185
1890	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)
1891	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)
1892	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)
1893	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)
1894	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)
1895		2191
…		…
1944		2240
1945	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
1946	monotonic clock option at both compiletime and runtime. Otherwise no use	2242	monotonic clock option at both compiletime and runtime. Otherwise no use
1947	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
1948	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
1949	the functionality isn't available is safe, though, althoguh you have	2245	the functionality isn't available is safe, though, although you have
1950	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>
1951	function is hiding in (often F<-lrt>).	2247	function is hiding in (often F<-lrt>).
1952		2248
1953	=item EV_USE_REALTIME	2249	=item EV_USE_REALTIME
1954		2250
1955	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
1956	realtime clock option at compiletime (and assume its availability at	2252	realtime clock option at compiletime (and assume its availability at
1957	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
1958	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2254	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
1959	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2255	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
1960	in the description of C<EV_USE_MONOTONIC>, though.	2256	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
1961		2257
1962	=item EV_USE_SELECT	2258	=item EV_USE_SELECT
1963		2259
1964	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
1965	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
…		…
2058	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
2059	additional independent event loops. Otherwise there will be no support	2355	additional independent event loops. Otherwise there will be no support
2060	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
2061	argument. Instead, all functions act on the single default loop.	2357	argument. Instead, all functions act on the single default loop.
2062		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
2063	=item EV_PERIODIC_ENABLE	2376	=item EV_PERIODIC_ENABLE
2064		2377
2065	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
2066	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
2067	code.	2386	code.
2068		2387
2069	=item EV_EMBED_ENABLE	2388	=item EV_EMBED_ENABLE
2070		2389
…		…
2121		2440
2122	=item ev_set_cb (ev, cb)	2441	=item ev_set_cb (ev, cb)
2123		2442
2124	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,
2125	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
2126	definition and a statement, respectively. See the F<ev.v> header file for	2445	definition and a statement, respectively. See the F<ev.h> header file for
2127	their default definitions. One possible use for overriding these is to	2446	their default definitions. One possible use for overriding these is to
2128	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
2129	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	...
2130		2474
2131	=head2 EXAMPLES	2475	=head2 EXAMPLES
2132		2476
2133	For a real-world example of a program the includes libev	2477	For a real-world example of a program the includes libev
2134	verbatim, you can have a look at the EV perl module	2478	verbatim, you can have a look at the EV perl module
…		…
2137	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
2138	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
2139	file.	2483	file.
2140		2484
2141	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
2142	that everybody includes and which overrides some autoconf choices:	2486	that everybody includes and which overrides some configure choices:
2143		2487
		2488	#define EV_MINIMAL 1
2144	#define EV_USE_POLL 0	2489	#define EV_USE_POLL 0
2145	#define EV_MULTIPLICITY 0	2490	#define EV_MULTIPLICITY 0
2146	#define EV_PERIODICS 0	2491	#define EV_PERIODIC_ENABLE 0
		2492	#define EV_STAT_ENABLE 0
		2493	#define EV_FORK_ENABLE 0
2147	#define EV_CONFIG_H <config.h>	2494	#define EV_CONFIG_H <config.h>
		2495	#define EV_MINPRI 0
		2496	#define EV_MAXPRI 0
2148		2497
2149	#include "ev++.h"	2498	#include "ev++.h"
2150		2499
2151	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:
2152		2501
…		…
2158		2507
2159	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
2160	libev will be explained. For complexity discussions about backends see the	2509	libev will be explained. For complexity discussions about backends see the
2161	documentation for C<ev_default_init>.	2510	documentation for C<ev_default_init>.
2162		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
2163	=over 4	2518	=over 4
2164		2519
2165	=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)
2166		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
2167	=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)
2168		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
2169	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2531	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2170		2532
		2533	These just add the watcher into an array or at the head of a list.
2171	=item Stopping check/prepare/idle watchers: O(1)	2534	=item Stopping check/prepare/idle watchers: O(1)
2172		2535
2173	=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))
2174		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
2175	=item Finding the next timer per loop iteration: O(1)	2542	=item Finding the next timer per loop iteration: O(1)
2176		2543
2177	=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)
2178		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
2179	=item Activating one watcher: O(1)	2549	=item Activating one watcher: O(1)
2180		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
2181	=back	2557	=back
2182		2558
2183		2559
2184	=head1 AUTHOR	2560	=head1 AUTHOR
2185		2561

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Comparing libev/ev.pod (file contents): Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC vs. Revision 1.93 by root, Fri Dec 21 01:29:34 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC vs.
Revision 1.93 by root, Fri Dec 21 01:29:34 2007 UTC