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

Comparing libev/ev.pod (file contents):
Revision 1.69 by root, Fri Dec 7 19:15:39 2007 UTC vs.
Revision 1.99 by root, Sat Dec 22 06:16:36 2007 UTC

…		…
53	The newest version of this document is also available as a html-formatted	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	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>.	55	time: L<http://cvs.schmorp.de/libev/ev.html>.
56		56
57	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
58	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
59	these event sources and provide your program with events.	59	these event sources and provide your program with events.
60		60
61	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
62	(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
63	communicate events via a callback mechanism.	63	communicate events via a callback mechanism.
…		…
98	Libev represents time as a single floating point number, representing the	98	Libev represents time as a single floating point number, representing the
99	(fractional) number of seconds since the (POSIX) epoch (somewhere near	99	(fractional) number of seconds since the (POSIX) epoch (somewhere near
100	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
101	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
102	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
103	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.
104		106
105	=head1 GLOBAL FUNCTIONS	107	=head1 GLOBAL FUNCTIONS
106		108
107	These functions can be called anytime, even before initialising the	109	These functions can be called anytime, even before initialising the
108	library in any way.	110	library in any way.
…		…
113		115
114	Returns the current time as libev would use it. Please note that the	116	Returns the current time as libev would use it. Please note that the
115	C<ev_now> function is usually faster and also often returns the timestamp	117	C<ev_now> function is usually faster and also often returns the timestamp
116	you actually want to know.	118	you actually want to know.
117		119
		120	=item ev_sleep (ev_tstamp interval)
		121
		122	Sleep for the given interval: The current thread will be blocked until
		123	either it is interrupted or the given time interval has passed. Basically
		124	this is a subsecond-resolution C<sleep ()>.
		125
118	=item int ev_version_major ()	126	=item int ev_version_major ()
119		127
120	=item int ev_version_minor ()	128	=item int ev_version_minor ()
121		129
122	You can find out the major and minor version numbers of the library	130	You can find out the major and minor ABI version numbers of the library
123	you linked against by calling the functions C<ev_version_major> and	131	you linked against by calling the functions C<ev_version_major> and
124	C<ev_version_minor>. If you want, you can compare against the global	132	C<ev_version_minor>. If you want, you can compare against the global
125	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the	133	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
126	version of the library your program was compiled against.	134	version of the library your program was compiled against.
127		135
		136	These version numbers refer to the ABI version of the library, not the
		137	release version.
		138
128	Usually, it's a good idea to terminate if the major versions mismatch,	139	Usually, it's a good idea to terminate if the major versions mismatch,
129	as this indicates an incompatible change. Minor versions are usually	140	as this indicates an incompatible change. Minor versions are usually
130	compatible to older versions, so a larger minor version alone is usually	141	compatible to older versions, so a larger minor version alone is usually
131	not a problem.	142	not a problem.
132		143
133	Example: Make sure we haven't accidentally been linked against the wrong	144	Example: Make sure we haven't accidentally been linked against the wrong
134	version.	145	version.
…		…
308	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).	319	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
309		320
310	=item C<EVBACKEND_EPOLL> (value 4, Linux)	321	=item C<EVBACKEND_EPOLL> (value 4, Linux)
311		322
312	For few fds, this backend is a bit little slower than poll and select,	323	For few fds, this backend is a bit little slower than poll and select,
313	but it scales phenomenally better. While poll and select usually scale like	324	but it scales phenomenally better. While poll and select usually scale
314	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales	325	like O(total_fds) where n is the total number of fds (or the highest fd),
315	either O(1) or O(active_fds).	326	epoll scales either O(1) or O(active_fds). The epoll design has a number
		327	of shortcomings, such as silently dropping events in some hard-to-detect
		328	cases and rewiring a syscall per fd change, no fork support and bad
		329	support for dup:
316		330
317	While stopping and starting an I/O watcher in the same iteration will	331	While stopping, setting and starting an I/O watcher in the same iteration
318	result in some caching, there is still a syscall per such incident	332	will result in some caching, there is still a syscall per such incident
319	(because the fd could point to a different file description now), so its	333	(because the fd could point to a different file description now), so its
320	best to avoid that. Also, dup()ed file descriptors might not work very	334	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
321	well if you register events for both fds.	335	very well if you register events for both fds.
322		336
323	Please note that epoll sometimes generates spurious notifications, so you	337	Please note that epoll sometimes generates spurious notifications, so you
324	need to use non-blocking I/O or other means to avoid blocking when no data	338	need to use non-blocking I/O or other means to avoid blocking when no data
325	(or space) is available.	339	(or space) is available.
326		340
327	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	341	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
328		342
329	Kqueue deserves special mention, as at the time of this writing, it	343	Kqueue deserves special mention, as at the time of this writing, it
330	was broken on all BSDs except NetBSD (usually it doesn't work with	344	was broken on I<all> BSDs (usually it doesn't work with anything but
331	anything but sockets and pipes, except on Darwin, where of course its	345	sockets and pipes, except on Darwin, where of course it's completely
		346	useless. On NetBSD, it seems to work for all the FD types I tested, so it
332	completely useless). For this reason its not being "autodetected"	347	is used by default there). For this reason it's not being "autodetected"
333	unless you explicitly specify it explicitly in the flags (i.e. using	348	unless you explicitly specify it explicitly in the flags (i.e. using
334	C<EVBACKEND_KQUEUE>).	349	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
		350	system like NetBSD.
335		351
336	It scales in the same way as the epoll backend, but the interface to the	352	It scales in the same way as the epoll backend, but the interface to the
337	kernel is more efficient (which says nothing about its actual speed, of	353	kernel is more efficient (which says nothing about its actual speed,
338	course). While starting and stopping an I/O watcher does not cause an	354	of course). While stopping, setting and starting an I/O watcher does
339	extra syscall as with epoll, it still adds up to four event changes per	355	never cause an extra syscall as with epoll, it still adds up to two event
340	incident, so its best to avoid that.	356	changes per incident, support for C<fork ()> is very bad and it drops fds
		357	silently in similarly hard-to-detetc cases.
341		358
342	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	359	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
343		360
344	This is not implemented yet (and might never be).	361	This is not implemented yet (and might never be).
345		362
346	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	363	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
347		364
348	This uses the Solaris 10 port mechanism. As with everything on Solaris,	365	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
349	it's really slow, but it still scales very well (O(active_fds)).	366	it's really slow, but it still scales very well (O(active_fds)).
350		367
351	Please note that solaris ports can result in a lot of spurious	368	Please note that solaris event ports can deliver a lot of spurious
352	notifications, so you need to use non-blocking I/O or other means to avoid	369	notifications, so you need to use non-blocking I/O or other means to avoid
353	blocking when no data (or space) is available.	370	blocking when no data (or space) is available.
354		371
355	=item C<EVBACKEND_ALL>	372	=item C<EVBACKEND_ALL>
356		373
…		…
399	Destroys the default loop again (frees all memory and kernel state	416	Destroys the default loop again (frees all memory and kernel state
400	etc.). None of the active event watchers will be stopped in the normal	417	etc.). None of the active event watchers will be stopped in the normal
401	sense, so e.g. C<ev_is_active> might still return true. It is your	418	sense, so e.g. C<ev_is_active> might still return true. It is your
402	responsibility to either stop all watchers cleanly yoursef I<before>	419	responsibility to either stop all watchers cleanly yoursef I<before>
403	calling this function, or cope with the fact afterwards (which is usually	420	calling this function, or cope with the fact afterwards (which is usually
404	the easiest thing, youc na just ignore the watchers and/or C<free ()> them	421	the easiest thing, you can just ignore the watchers and/or C<free ()> them
405	for example).	422	for example).
		423
		424	Note that certain global state, such as signal state, will not be freed by
		425	this function, and related watchers (such as signal and child watchers)
		426	would need to be stopped manually.
		427
		428	In general it is not advisable to call this function except in the
		429	rare occasion where you really need to free e.g. the signal handling
		430	pipe fds. If you need dynamically allocated loops it is better to use
		431	C<ev_loop_new> and C<ev_loop_destroy>).
406		432
407	=item ev_loop_destroy (loop)	433	=item ev_loop_destroy (loop)
408		434
409	Like C<ev_default_destroy>, but destroys an event loop created by an	435	Like C<ev_default_destroy>, but destroys an event loop created by an
410	earlier call to C<ev_loop_new>.	436	earlier call to C<ev_loop_new>.
…		…
455		481
456	Returns the current "event loop time", which is the time the event loop	482	Returns the current "event loop time", which is the time the event loop
457	received events and started processing them. This timestamp does not	483	received events and started processing them. This timestamp does not
458	change as long as callbacks are being processed, and this is also the base	484	change as long as callbacks are being processed, and this is also the base
459	time used for relative timers. You can treat it as the timestamp of the	485	time used for relative timers. You can treat it as the timestamp of the
460	event occuring (or more correctly, libev finding out about it).	486	event occurring (or more correctly, libev finding out about it).
461		487
462	=item ev_loop (loop, int flags)	488	=item ev_loop (loop, int flags)
463		489
464	Finally, this is it, the event handler. This function usually is called	490	Finally, this is it, the event handler. This function usually is called
465	after you initialised all your watchers and you want to start handling	491	after you initialised all your watchers and you want to start handling
…		…
486	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	512	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
487	usually a better approach for this kind of thing.	513	usually a better approach for this kind of thing.
488		514
489	Here are the gory details of what C<ev_loop> does:	515	Here are the gory details of what C<ev_loop> does:
490		516
		517	- Before the first iteration, call any pending watchers.
491	* If there are no active watchers (reference count is zero), return.	518	* If there are no active watchers (reference count is zero), return.
492	- Queue prepare watchers and then call all outstanding watchers.	519	- Queue all prepare watchers and then call all outstanding watchers.
493	- If we have been forked, recreate the kernel state.	520	- If we have been forked, recreate the kernel state.
494	- Update the kernel state with all outstanding changes.	521	- Update the kernel state with all outstanding changes.
495	- Update the "event loop time".	522	- Update the "event loop time".
496	- Calculate for how long to block.	523	- Calculate for how long to block.
497	- Block the process, waiting for any events.	524	- Block the process, waiting for any events.
…		…
548	Example: For some weird reason, unregister the above signal handler again.	575	Example: For some weird reason, unregister the above signal handler again.
549		576
550	ev_ref (loop);	577	ev_ref (loop);
551	ev_signal_stop (loop, &exitsig);	578	ev_signal_stop (loop, &exitsig);
552		579
		580	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
		581
		582	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
		583
		584	These advanced functions influence the time that libev will spend waiting
		585	for events. Both are by default C<0>, meaning that libev will try to
		586	invoke timer/periodic callbacks and I/O callbacks with minimum latency.
		587
		588	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
		589	allows libev to delay invocation of I/O and timer/periodic callbacks to
		590	increase efficiency of loop iterations.
		591
		592	The background is that sometimes your program runs just fast enough to
		593	handle one (or very few) event(s) per loop iteration. While this makes
		594	the program responsive, it also wastes a lot of CPU time to poll for new
		595	events, especially with backends like C<select ()> which have a high
		596	overhead for the actual polling but can deliver many events at once.
		597
		598	By setting a higher I<io collect interval> you allow libev to spend more
		599	time collecting I/O events, so you can handle more events per iteration,
		600	at the cost of increasing latency. Timeouts (both C<ev_periodic> and
		601	C<ev_timer>) will be not affected. Setting this to a non-null bvalue will
		602	introduce an additional C<ev_sleep ()> call into most loop iterations.
		603
		604	Likewise, by setting a higher I<timeout collect interval> you allow libev
		605	to spend more time collecting timeouts, at the expense of increased
		606	latency (the watcher callback will be called later). C<ev_io> watchers
		607	will not be affected. Setting this to a non-null value will not introduce
		608	any overhead in libev.
		609
		610	Many (busy) programs can usually benefit by setting the io collect
		611	interval to a value near C<0.1> or so, which is often enough for
		612	interactive servers (of course not for games), likewise for timeouts. It
		613	usually doesn't make much sense to set it to a lower value than C<0.01>,
		614	as this approsaches the timing granularity of most systems.
		615
553	=back	616	=back
554		617
555		618
556	=head1 ANATOMY OF A WATCHER	619	=head1 ANATOMY OF A WATCHER
557		620
…		…
736	=item bool ev_is_pending (ev_TYPE *watcher)	799	=item bool ev_is_pending (ev_TYPE *watcher)
737		800
738	Returns a true value iff the watcher is pending, (i.e. it has outstanding	801	Returns a true value iff the watcher is pending, (i.e. it has outstanding
739	events but its callback has not yet been invoked). As long as a watcher	802	events but its callback has not yet been invoked). As long as a watcher
740	is pending (but not active) you must not call an init function on it (but	803	is pending (but not active) you must not call an init function on it (but
741	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	804	C<ev_TYPE_set> is safe), you must not change its priority, and you must
742	libev (e.g. you cnanot C<free ()> it).	805	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		806	it).
743		807
744	=item callback ev_cb (ev_TYPE *watcher)	808	=item callback ev_cb (ev_TYPE *watcher)
745		809
746	Returns the callback currently set on the watcher.	810	Returns the callback currently set on the watcher.
747		811
…		…
766	watchers on the same event and make sure one is called first.	830	watchers on the same event and make sure one is called first.
767		831
768	If you need to suppress invocation when higher priority events are pending	832	If you need to suppress invocation when higher priority events are pending
769	you need to look at C<ev_idle> watchers, which provide this functionality.	833	you need to look at C<ev_idle> watchers, which provide this functionality.
770		834
		835	You I<must not> change the priority of a watcher as long as it is active or
		836	pending.
		837
771	The default priority used by watchers when no priority has been set is	838	The default priority used by watchers when no priority has been set is
772	always C<0>, which is supposed to not be too high and not be too low :).	839	always C<0>, which is supposed to not be too high and not be too low :).
773		840
774	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is	841	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
775	fine, as long as you do not mind that the priority value you query might	842	fine, as long as you do not mind that the priority value you query might
776	or might not have been adjusted to be within valid range.	843	or might not have been adjusted to be within valid range.
		844
		845	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		846
		847	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		848	C<loop> nor C<revents> need to be valid as long as the watcher callback
		849	can deal with that fact.
		850
		851	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		852
		853	If the watcher is pending, this function returns clears its pending status
		854	and returns its C<revents> bitset (as if its callback was invoked). If the
		855	watcher isn't pending it does nothing and returns C<0>.
777		856
778	=back	857	=back
779		858
780		859
781	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	860	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
891	play around with an Xlib connection), then you have to seperately re-test	970	play around with an Xlib connection), then you have to seperately re-test
892	whether a file descriptor is really ready with a known-to-be good interface	971	whether a file descriptor is really ready with a known-to-be good interface
893	such as poll (fortunately in our Xlib example, Xlib already does this on	972	such as poll (fortunately in our Xlib example, Xlib already does this on
894	its own, so its quite safe to use).	973	its own, so its quite safe to use).
895		974
		975	=head3 The special problem of disappearing file descriptors
		976
		977	Some backends (e.g. kqueue, epoll) need to be told about closing a file
		978	descriptor (either by calling C<close> explicitly or by any other means,
		979	such as C<dup>). The reason is that you register interest in some file
		980	descriptor, but when it goes away, the operating system will silently drop
		981	this interest. If another file descriptor with the same number then is
		982	registered with libev, there is no efficient way to see that this is, in
		983	fact, a different file descriptor.
		984
		985	To avoid having to explicitly tell libev about such cases, libev follows
		986	the following policy: Each time C<ev_io_set> is being called, libev
		987	will assume that this is potentially a new file descriptor, otherwise
		988	it is assumed that the file descriptor stays the same. That means that
		989	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		990	descriptor even if the file descriptor number itself did not change.
		991
		992	This is how one would do it normally anyway, the important point is that
		993	the libev application should not optimise around libev but should leave
		994	optimisations to libev.
		995
		996	=head3 The special problem of dup'ed file descriptors
		997
		998	Some backends (e.g. epoll), cannot register events for file descriptors,
		999	but only events for the underlying file descriptions. That menas when you
		1000	have C<dup ()>'ed file descriptors and register events for them, only one
		1001	file descriptor might actually receive events.
		1002
		1003	There is no workaorund possible except not registering events
		1004	for potentially C<dup ()>'ed file descriptors or to resort to
		1005	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
		1006
		1007	=head3 The special problem of fork
		1008
		1009	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
		1010	useless behaviour. Libev fully supports fork, but needs to be told about
		1011	it in the child.
		1012
		1013	To support fork in your programs, you either have to call
		1014	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
		1015	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
		1016	C<EVBACKEND_POLL>.
		1017
		1018
		1019	=head3 Watcher-Specific Functions
		1020
896	=over 4	1021	=over 4
897		1022
898	=item ev_io_init (ev_io *, callback, int fd, int events)	1023	=item ev_io_init (ev_io *, callback, int fd, int events)
899		1024
900	=item ev_io_set (ev_io *, int fd, int events)	1025	=item ev_io_set (ev_io *, int fd, int events)
…		…
952	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1077	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
953		1078
954	The callback is guarenteed to be invoked only when its timeout has passed,	1079	The callback is guarenteed to be invoked only when its timeout has passed,
955	but if multiple timers become ready during the same loop iteration then	1080	but if multiple timers become ready during the same loop iteration then
956	order of execution is undefined.	1081	order of execution is undefined.
		1082
		1083	=head3 Watcher-Specific Functions and Data Members
957		1084
958	=over 4	1085	=over 4
959		1086
960	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1087	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
961		1088
…		…
1057	but on wallclock time (absolute time). You can tell a periodic watcher	1184	but on wallclock time (absolute time). You can tell a periodic watcher
1058	to trigger "at" some specific point in time. For example, if you tell a	1185	to trigger "at" some specific point in time. For example, if you tell a
1059	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1186	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
1060	+ 10.>) and then reset your system clock to the last year, then it will	1187	+ 10.>) and then reset your system clock to the last year, then it will
1061	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1188	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
1062	roughly 10 seconds later and of course not if you reset your system time	1189	roughly 10 seconds later).
1063	again).
1064		1190
1065	They can also be used to implement vastly more complex timers, such as	1191	They can also be used to implement vastly more complex timers, such as
1066	triggering an event on eahc midnight, local time.	1192	triggering an event on each midnight, local time or other, complicated,
		1193	rules.
1067		1194
1068	As with timers, the callback is guarenteed to be invoked only when the	1195	As with timers, the callback is guarenteed to be invoked only when the
1069	time (C<at>) has been passed, but if multiple periodic timers become ready	1196	time (C<at>) has been passed, but if multiple periodic timers become ready
1070	during the same loop iteration then order of execution is undefined.	1197	during the same loop iteration then order of execution is undefined.
1071		1198
		1199	=head3 Watcher-Specific Functions and Data Members
		1200
1072	=over 4	1201	=over 4
1073		1202
1074	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1203	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
1075		1204
1076	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1205	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
1078	Lots of arguments, lets sort it out... There are basically three modes of	1207	Lots of arguments, lets sort it out... There are basically three modes of
1079	operation, and we will explain them from simplest to complex:	1208	operation, and we will explain them from simplest to complex:
1080		1209
1081	=over 4	1210	=over 4
1082		1211
1083	=item * absolute timer (interval = reschedule_cb = 0)	1212	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1084		1213
1085	In this configuration the watcher triggers an event at the wallclock time	1214	In this configuration the watcher triggers an event at the wallclock time
1086	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1215	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
1087	that is, if it is to be run at January 1st 2011 then it will run when the	1216	that is, if it is to be run at January 1st 2011 then it will run when the
1088	system time reaches or surpasses this time.	1217	system time reaches or surpasses this time.
1089		1218
1090	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1219	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1091		1220
1092	In this mode the watcher will always be scheduled to time out at the next	1221	In this mode the watcher will always be scheduled to time out at the next
1093	C<at + N * interval> time (for some integer N) and then repeat, regardless	1222	C<at + N * interval> time (for some integer N, which can also be negative)
1094	of any time jumps.	1223	and then repeat, regardless of any time jumps.
1095		1224
1096	This can be used to create timers that do not drift with respect to system	1225	This can be used to create timers that do not drift with respect to system
1097	time:	1226	time:
1098		1227
1099	ev_periodic_set (&periodic, 0., 3600., 0);	1228	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1105		1234
1106	Another way to think about it (for the mathematically inclined) is that	1235	Another way to think about it (for the mathematically inclined) is that
1107	C<ev_periodic> will try to run the callback in this mode at the next possible	1236	C<ev_periodic> will try to run the callback in this mode at the next possible
1108	time where C<time = at (mod interval)>, regardless of any time jumps.	1237	time where C<time = at (mod interval)>, regardless of any time jumps.
1109		1238
		1239	For numerical stability it is preferable that the C<at> value is near
		1240	C<ev_now ()> (the current time), but there is no range requirement for
		1241	this value.
		1242
1110	=item * manual reschedule mode (reschedule_cb = callback)	1243	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1111		1244
1112	In this mode the values for C<interval> and C<at> are both being	1245	In this mode the values for C<interval> and C<at> are both being
1113	ignored. Instead, each time the periodic watcher gets scheduled, the	1246	ignored. Instead, each time the periodic watcher gets scheduled, the
1114	reschedule callback will be called with the watcher as first, and the	1247	reschedule callback will be called with the watcher as first, and the
1115	current time as second argument.	1248	current time as second argument.
1116		1249
1117	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1250	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1118	ever, or make any event loop modifications>. If you need to stop it,	1251	ever, or make any event loop modifications>. If you need to stop it,
1119	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1252	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1120	starting a prepare watcher).	1253	starting an C<ev_prepare> watcher, which is legal).
1121		1254
1122	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	1255	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
1123	ev_tstamp now)>, e.g.:	1256	ev_tstamp now)>, e.g.:
1124		1257
1125	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1258	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
1148	Simply stops and restarts the periodic watcher again. This is only useful	1281	Simply stops and restarts the periodic watcher again. This is only useful
1149	when you changed some parameters or the reschedule callback would return	1282	when you changed some parameters or the reschedule callback would return
1150	a different time than the last time it was called (e.g. in a crond like	1283	a different time than the last time it was called (e.g. in a crond like
1151	program when the crontabs have changed).	1284	program when the crontabs have changed).
1152		1285
		1286	=item ev_tstamp offset [read-write]
		1287
		1288	When repeating, this contains the offset value, otherwise this is the
		1289	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1290
		1291	Can be modified any time, but changes only take effect when the periodic
		1292	timer fires or C<ev_periodic_again> is being called.
		1293
1153	=item ev_tstamp interval [read-write]	1294	=item ev_tstamp interval [read-write]
1154		1295
1155	The current interval value. Can be modified any time, but changes only	1296	The current interval value. Can be modified any time, but changes only
1156	take effect when the periodic timer fires or C<ev_periodic_again> is being	1297	take effect when the periodic timer fires or C<ev_periodic_again> is being
1157	called.	1298	called.
…		…
1159	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]	1300	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
1160		1301
1161	The current reschedule callback, or C<0>, if this functionality is	1302	The current reschedule callback, or C<0>, if this functionality is
1162	switched off. Can be changed any time, but changes only take effect when	1303	switched off. Can be changed any time, but changes only take effect when
1163	the periodic timer fires or C<ev_periodic_again> is being called.	1304	the periodic timer fires or C<ev_periodic_again> is being called.
		1305
		1306	=item ev_tstamp at [read-only]
		1307
		1308	When active, contains the absolute time that the watcher is supposed to
		1309	trigger next.
1164		1310
1165	=back	1311	=back
1166		1312
1167	Example: Call a callback every hour, or, more precisely, whenever the	1313	Example: Call a callback every hour, or, more precisely, whenever the
1168	system clock is divisible by 3600. The callback invocation times have	1314	system clock is divisible by 3600. The callback invocation times have
…		…
1210	with the kernel (thus it coexists with your own signal handlers as long	1356	with the kernel (thus it coexists with your own signal handlers as long
1211	as you don't register any with libev). Similarly, when the last signal	1357	as you don't register any with libev). Similarly, when the last signal
1212	watcher for a signal is stopped libev will reset the signal handler to	1358	watcher for a signal is stopped libev will reset the signal handler to
1213	SIG_DFL (regardless of what it was set to before).	1359	SIG_DFL (regardless of what it was set to before).
1214		1360
		1361	=head3 Watcher-Specific Functions and Data Members
		1362
1215	=over 4	1363	=over 4
1216		1364
1217	=item ev_signal_init (ev_signal *, callback, int signum)	1365	=item ev_signal_init (ev_signal *, callback, int signum)
1218		1366
1219	=item ev_signal_set (ev_signal *, int signum)	1367	=item ev_signal_set (ev_signal *, int signum)
…		…
1230		1378
1231	=head2 C<ev_child> - watch out for process status changes	1379	=head2 C<ev_child> - watch out for process status changes
1232		1380
1233	Child watchers trigger when your process receives a SIGCHLD in response to	1381	Child watchers trigger when your process receives a SIGCHLD in response to
1234	some child status changes (most typically when a child of yours dies).	1382	some child status changes (most typically when a child of yours dies).
		1383
		1384	=head3 Watcher-Specific Functions and Data Members
1235		1385
1236	=over 4	1386	=over 4
1237		1387
1238	=item ev_child_init (ev_child *, callback, int pid)	1388	=item ev_child_init (ev_child *, callback, int pid)
1239		1389
…		…
1307	reader). Inotify will be used to give hints only and should not change the	1457	reader). Inotify will be used to give hints only and should not change the
1308	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1458	semantics of C<ev_stat> watchers, which means that libev sometimes needs
1309	to fall back to regular polling again even with inotify, but changes are	1459	to fall back to regular polling again even with inotify, but changes are
1310	usually detected immediately, and if the file exists there will be no	1460	usually detected immediately, and if the file exists there will be no
1311	polling.	1461	polling.
		1462
		1463	=head3 Watcher-Specific Functions and Data Members
1312		1464
1313	=over 4	1465	=over 4
1314		1466
1315	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1467	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1316		1468
…		…
1399	Apart from keeping your process non-blocking (which is a useful	1551	Apart from keeping your process non-blocking (which is a useful
1400	effect on its own sometimes), idle watchers are a good place to do	1552	effect on its own sometimes), idle watchers are a good place to do
1401	"pseudo-background processing", or delay processing stuff to after the	1553	"pseudo-background processing", or delay processing stuff to after the
1402	event loop has handled all outstanding events.	1554	event loop has handled all outstanding events.
1403		1555
		1556	=head3 Watcher-Specific Functions and Data Members
		1557
1404	=over 4	1558	=over 4
1405		1559
1406	=item ev_idle_init (ev_signal *, callback)	1560	=item ev_idle_init (ev_signal *, callback)
1407		1561
1408	Initialises and configures the idle watcher - it has no parameters of any	1562	Initialises and configures the idle watcher - it has no parameters of any
…		…
1465	with priority higher than or equal to the event loop and one coroutine	1619	with priority higher than or equal to the event loop and one coroutine
1466	of lower priority, but only once, using idle watchers to keep the event	1620	of lower priority, but only once, using idle watchers to keep the event
1467	loop from blocking if lower-priority coroutines are active, thus mapping	1621	loop from blocking if lower-priority coroutines are active, thus mapping
1468	low-priority coroutines to idle/background tasks).	1622	low-priority coroutines to idle/background tasks).
1469		1623
		1624	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1625	priority, to ensure that they are being run before any other watchers
		1626	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1627	too) should not activate ("feed") events into libev. While libev fully
		1628	supports this, they will be called before other C<ev_check> watchers did
		1629	their job. As C<ev_check> watchers are often used to embed other event
		1630	loops those other event loops might be in an unusable state until their
		1631	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1632	others).
		1633
		1634	=head3 Watcher-Specific Functions and Data Members
		1635
1470	=over 4	1636	=over 4
1471		1637
1472	=item ev_prepare_init (ev_prepare *, callback)	1638	=item ev_prepare_init (ev_prepare *, callback)
1473		1639
1474	=item ev_check_init (ev_check *, callback)	1640	=item ev_check_init (ev_check *, callback)
…		…
1477	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1643	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1478	macros, but using them is utterly, utterly and completely pointless.	1644	macros, but using them is utterly, utterly and completely pointless.
1479		1645
1480	=back	1646	=back
1481		1647
1482	Example: To include a library such as adns, you would add IO watchers	1648	There are a number of principal ways to embed other event loops or modules
1483	and a timeout watcher in a prepare handler, as required by libadns, and	1649	into libev. Here are some ideas on how to include libadns into libev
		1650	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1651	use for an actually working example. Another Perl module named C<EV::Glib>
		1652	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1653	into the Glib event loop).
		1654
		1655	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1484	in a check watcher, destroy them and call into libadns. What follows is	1656	and in a check watcher, destroy them and call into libadns. What follows
1485	pseudo-code only of course:	1657	is pseudo-code only of course. This requires you to either use a low
		1658	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1659	the callbacks for the IO/timeout watchers might not have been called yet.
1486		1660
1487	static ev_io iow [nfd];	1661	static ev_io iow [nfd];
1488	static ev_timer tw;	1662	static ev_timer tw;
1489		1663
1490	static void	1664	static void
1491	io_cb (ev_loop loop, ev_io w, int revents)	1665	io_cb (ev_loop loop, ev_io w, int revents)
1492	{	1666	{
1493	// set the relevant poll flags
1494	// could also call adns_processreadable etc. here
1495	struct pollfd fd = (struct pollfd )w->data;
1496	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1497	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1498	}	1667	}
1499		1668
1500	// create io watchers for each fd and a timer before blocking	1669	// create io watchers for each fd and a timer before blocking
1501	static void	1670	static void
1502	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1671	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
…		…
1508		1677
1509	/* the callback is illegal, but won't be called as we stop during check */	1678	/* the callback is illegal, but won't be called as we stop during check */
1510	ev_timer_init (&tw, 0, timeout * 1e-3);	1679	ev_timer_init (&tw, 0, timeout * 1e-3);
1511	ev_timer_start (loop, &tw);	1680	ev_timer_start (loop, &tw);
1512		1681
1513	// create on ev_io per pollfd	1682	// create one ev_io per pollfd
1514	for (int i = 0; i < nfd; ++i)	1683	for (int i = 0; i < nfd; ++i)
1515	{	1684	{
1516	ev_io_init (iow + i, io_cb, fds [i].fd,	1685	ev_io_init (iow + i, io_cb, fds [i].fd,
1517	((fds [i].events & POLLIN ? EV_READ : 0)	1686	((fds [i].events & POLLIN ? EV_READ : 0)
1518	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1687	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1519		1688
1520	fds [i].revents = 0;	1689	fds [i].revents = 0;
1521	iow [i].data = fds + i;
1522	ev_io_start (loop, iow + i);	1690	ev_io_start (loop, iow + i);
1523	}	1691	}
1524	}	1692	}
1525		1693
1526	// stop all watchers after blocking	1694	// stop all watchers after blocking
…		…
1528	adns_check_cb (ev_loop loop, ev_check w, int revents)	1696	adns_check_cb (ev_loop loop, ev_check w, int revents)
1529	{	1697	{
1530	ev_timer_stop (loop, &tw);	1698	ev_timer_stop (loop, &tw);
1531		1699
1532	for (int i = 0; i < nfd; ++i)	1700	for (int i = 0; i < nfd; ++i)
		1701	{
		1702	// set the relevant poll flags
		1703	// could also call adns_processreadable etc. here
		1704	struct pollfd *fd = fds + i;
		1705	int revents = ev_clear_pending (iow + i);
		1706	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1707	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1708
		1709	// now stop the watcher
1533	ev_io_stop (loop, iow + i);	1710	ev_io_stop (loop, iow + i);
		1711	}
1534		1712
1535	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1713	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1714	}
		1715
		1716	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1717	in the prepare watcher and would dispose of the check watcher.
		1718
		1719	Method 3: If the module to be embedded supports explicit event
		1720	notification (adns does), you can also make use of the actual watcher
		1721	callbacks, and only destroy/create the watchers in the prepare watcher.
		1722
		1723	static void
		1724	timer_cb (EV_P_ ev_timer *w, int revents)
		1725	{
		1726	adns_state ads = (adns_state)w->data;
		1727	update_now (EV_A);
		1728
		1729	adns_processtimeouts (ads, &tv_now);
		1730	}
		1731
		1732	static void
		1733	io_cb (EV_P_ ev_io *w, int revents)
		1734	{
		1735	adns_state ads = (adns_state)w->data;
		1736	update_now (EV_A);
		1737
		1738	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1739	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1740	}
		1741
		1742	// do not ever call adns_afterpoll
		1743
		1744	Method 4: Do not use a prepare or check watcher because the module you
		1745	want to embed is too inflexible to support it. Instead, youc na override
		1746	their poll function. The drawback with this solution is that the main
		1747	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1748	this.
		1749
		1750	static gint
		1751	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1752	{
		1753	int got_events = 0;
		1754
		1755	for (n = 0; n < nfds; ++n)
		1756	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1757
		1758	if (timeout >= 0)
		1759	// create/start timer
		1760
		1761	// poll
		1762	ev_loop (EV_A_ 0);
		1763
		1764	// stop timer again
		1765	if (timeout >= 0)
		1766	ev_timer_stop (EV_A_ &to);
		1767
		1768	// stop io watchers again - their callbacks should have set
		1769	for (n = 0; n < nfds; ++n)
		1770	ev_io_stop (EV_A_ iow [n]);
		1771
		1772	return got_events;
1536	}	1773	}
1537		1774
1538		1775
1539	=head2 C<ev_embed> - when one backend isn't enough...	1776	=head2 C<ev_embed> - when one backend isn't enough...
1540		1777
1541	This is a rather advanced watcher type that lets you embed one event loop	1778	This is a rather advanced watcher type that lets you embed one event loop
1542	into another (currently only C<ev_io> events are supported in the embedded	1779	into another (currently only C<ev_io> events are supported in the embedded
1543	loop, other types of watchers might be handled in a delayed or incorrect	1780	loop, other types of watchers might be handled in a delayed or incorrect
1544	fashion and must not be used).	1781	fashion and must not be used). (See portability notes, below).
1545		1782
1546	There are primarily two reasons you would want that: work around bugs and	1783	There are primarily two reasons you would want that: work around bugs and
1547	prioritise I/O.	1784	prioritise I/O.
1548		1785
1549	As an example for a bug workaround, the kqueue backend might only support	1786	As an example for a bug workaround, the kqueue backend might only support
…		…
1604	ev_embed_start (loop_hi, &embed);	1841	ev_embed_start (loop_hi, &embed);
1605	}	1842	}
1606	else	1843	else
1607	loop_lo = loop_hi;	1844	loop_lo = loop_hi;
1608		1845
		1846	=head2 Portability notes
		1847
		1848	Kqueue is nominally embeddable, but this is broken on all BSDs that I
		1849	tried, in various ways. Usually the embedded event loop will simply never
		1850	receive events, sometimes it will only trigger a few times, sometimes in a
		1851	loop. Epoll is also nominally embeddable, but many Linux kernel versions
		1852	will always eport the epoll fd as ready, even when no events are pending.
		1853
		1854	While libev allows embedding these backends (they are contained in
		1855	C<ev_embeddable_backends ()>), take extreme care that it will actually
		1856	work.
		1857
		1858	When in doubt, create a dynamic event loop forced to use sockets (this
		1859	usually works) and possibly another thread and a pipe or so to report to
		1860	your main event loop.
		1861
		1862	=head3 Watcher-Specific Functions and Data Members
		1863
1609	=over 4	1864	=over 4
1610		1865
1611	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)	1866	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)
1612		1867
1613	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)	1868	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)
…		…
1622		1877
1623	Make a single, non-blocking sweep over the embedded loop. This works	1878	Make a single, non-blocking sweep over the embedded loop. This works
1624	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1879	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1625	apropriate way for embedded loops.	1880	apropriate way for embedded loops.
1626		1881
1627	=item struct ev_loop *loop [read-only]	1882	=item struct ev_loop *other [read-only]
1628		1883
1629	The embedded event loop.	1884	The embedded event loop.
1630		1885
1631	=back	1886	=back
1632		1887
…		…
1639	event loop blocks next and before C<ev_check> watchers are being called,	1894	event loop blocks next and before C<ev_check> watchers are being called,
1640	and only in the child after the fork. If whoever good citizen calling	1895	and only in the child after the fork. If whoever good citizen calling
1641	C<ev_default_fork> cheats and calls it in the wrong process, the fork	1896	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1642	handlers will be invoked, too, of course.	1897	handlers will be invoked, too, of course.
1643		1898
		1899	=head3 Watcher-Specific Functions and Data Members
		1900
1644	=over 4	1901	=over 4
1645		1902
1646	=item ev_fork_init (ev_signal *, callback)	1903	=item ev_fork_init (ev_signal *, callback)
1647		1904
1648	Initialises and configures the fork watcher - it has no parameters of any	1905	Initialises and configures the fork watcher - it has no parameters of any
…		…
1744		2001
1745	To use it,	2002	To use it,
1746		2003
1747	#include <ev++.h>	2004	#include <ev++.h>
1748		2005
1749	(it is not installed by default). This automatically includes F<ev.h>	2006	This automatically includes F<ev.h> and puts all of its definitions (many
1750	and puts all of its definitions (many of them macros) into the global	2007	of them macros) into the global namespace. All C++ specific things are
1751	namespace. All C++ specific things are put into the C<ev> namespace.	2008	put into the C<ev> namespace. It should support all the same embedding
		2009	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1752		2010
1753	It should support all the same embedding options as F<ev.h>, most notably	2011	Care has been taken to keep the overhead low. The only data member the C++
1754	C<EV_MULTIPLICITY>.	2012	classes add (compared to plain C-style watchers) is the event loop pointer
		2013	that the watcher is associated with (or no additional members at all if
		2014	you disable C<EV_MULTIPLICITY> when embedding libev).
		2015
		2016	Currently, functions, and static and non-static member functions can be
		2017	used as callbacks. Other types should be easy to add as long as they only
		2018	need one additional pointer for context. If you need support for other
		2019	types of functors please contact the author (preferably after implementing
		2020	it).
1755		2021
1756	Here is a list of things available in the C<ev> namespace:	2022	Here is a list of things available in the C<ev> namespace:
1757		2023
1758	=over 4	2024	=over 4
1759		2025
…		…
1775		2041
1776	All of those classes have these methods:	2042	All of those classes have these methods:
1777		2043
1778	=over 4	2044	=over 4
1779		2045
1780	=item ev::TYPE::TYPE (object , object::method )	2046	=item ev::TYPE::TYPE ()
1781		2047
1782	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	2048	=item ev::TYPE::TYPE (struct ev_loop *)
1783		2049
1784	=item ev::TYPE::~TYPE	2050	=item ev::TYPE::~TYPE
1785		2051
1786	The constructor takes a pointer to an object and a method pointer to	2052	The constructor (optionally) takes an event loop to associate the watcher
1787	the event handler callback to call in this class. The constructor calls	2053	with. If it is omitted, it will use C<EV_DEFAULT>.
1788	C<ev_init> for you, which means you have to call the C<set> method	2054
1789	before starting it. If you do not specify a loop then the constructor	2055	The constructor calls C<ev_init> for you, which means you have to call the
1790	automatically associates the default loop with this watcher.	2056	C<set> method before starting it.
		2057
		2058	It will not set a callback, however: You have to call the templated C<set>
		2059	method to set a callback before you can start the watcher.
		2060
		2061	(The reason why you have to use a method is a limitation in C++ which does
		2062	not allow explicit template arguments for constructors).
1791		2063
1792	The destructor automatically stops the watcher if it is active.	2064	The destructor automatically stops the watcher if it is active.
		2065
		2066	=item w->set<class, &class::method> (object *)
		2067
		2068	This method sets the callback method to call. The method has to have a
		2069	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		2070	first argument and the C<revents> as second. The object must be given as
		2071	parameter and is stored in the C<data> member of the watcher.
		2072
		2073	This method synthesizes efficient thunking code to call your method from
		2074	the C callback that libev requires. If your compiler can inline your
		2075	callback (i.e. it is visible to it at the place of the C<set> call and
		2076	your compiler is good :), then the method will be fully inlined into the
		2077	thunking function, making it as fast as a direct C callback.
		2078
		2079	Example: simple class declaration and watcher initialisation
		2080
		2081	struct myclass
		2082	{
		2083	void io_cb (ev::io &w, int revents) { }
		2084	}
		2085
		2086	myclass obj;
		2087	ev::io iow;
		2088	iow.set <myclass, &myclass::io_cb> (&obj);
		2089
		2090	=item w->set<function> (void *data = 0)
		2091
		2092	Also sets a callback, but uses a static method or plain function as
		2093	callback. The optional C<data> argument will be stored in the watcher's
		2094	C<data> member and is free for you to use.
		2095
		2096	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2097
		2098	See the method-C<set> above for more details.
		2099
		2100	Example:
		2101
		2102	static void io_cb (ev::io &w, int revents) { }
		2103	iow.set <io_cb> ();
1793		2104
1794	=item w->set (struct ev_loop *)	2105	=item w->set (struct ev_loop *)
1795		2106
1796	Associates a different C<struct ev_loop> with this watcher. You can only	2107	Associates a different C<struct ev_loop> with this watcher. You can only
1797	do this when the watcher is inactive (and not pending either).	2108	do this when the watcher is inactive (and not pending either).
1798		2109
1799	=item w->set ([args])	2110	=item w->set ([args])
1800		2111
1801	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2112	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1802	called at least once. Unlike the C counterpart, an active watcher gets	2113	called at least once. Unlike the C counterpart, an active watcher gets
1803	automatically stopped and restarted.	2114	automatically stopped and restarted when reconfiguring it with this
		2115	method.
1804		2116
1805	=item w->start ()	2117	=item w->start ()
1806		2118
1807	Starts the watcher. Note that there is no C<loop> argument as the	2119	Starts the watcher. Note that there is no C<loop> argument, as the
1808	constructor already takes the loop.	2120	constructor already stores the event loop.
1809		2121
1810	=item w->stop ()	2122	=item w->stop ()
1811		2123
1812	Stops the watcher if it is active. Again, no C<loop> argument.	2124	Stops the watcher if it is active. Again, no C<loop> argument.
1813		2125
1814	=item w->again () C<ev::timer>, C<ev::periodic> only	2126	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1815		2127
1816	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2128	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1817	C<ev_TYPE_again> function.	2129	C<ev_TYPE_again> function.
1818		2130
1819	=item w->sweep () C<ev::embed> only	2131	=item w->sweep () (C<ev::embed> only)
1820		2132
1821	Invokes C<ev_embed_sweep>.	2133	Invokes C<ev_embed_sweep>.
1822		2134
1823	=item w->update () C<ev::stat> only	2135	=item w->update () (C<ev::stat> only)
1824		2136
1825	Invokes C<ev_stat_stat>.	2137	Invokes C<ev_stat_stat>.
1826		2138
1827	=back	2139	=back
1828		2140
…		…
1838		2150
1839	myclass ();	2151	myclass ();
1840	}	2152	}
1841		2153
1842	myclass::myclass (int fd)	2154	myclass::myclass (int fd)
1843	: io (this, &myclass::io_cb),
1844	idle (this, &myclass::idle_cb)
1845	{	2155	{
		2156	io .set <myclass, &myclass::io_cb > (this);
		2157	idle.set <myclass, &myclass::idle_cb> (this);
		2158
1846	io.start (fd, ev::READ);	2159	io.start (fd, ev::READ);
1847	}	2160	}
1848		2161
1849		2162
1850	=head1 MACRO MAGIC	2163	=head1 MACRO MAGIC
1851		2164
1852	Libev can be compiled with a variety of options, the most fundemantal is	2165	Libev can be compiled with a variety of options, the most fundamantal
1853	C<EV_MULTIPLICITY>. This option determines whether (most) functions and	2166	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1854	callbacks have an initial C<struct ev_loop *> argument.	2167	functions and callbacks have an initial C<struct ev_loop *> argument.
1855		2168
1856	To make it easier to write programs that cope with either variant, the	2169	To make it easier to write programs that cope with either variant, the
1857	following macros are defined:	2170	following macros are defined:
1858		2171
1859	=over 4	2172	=over 4
…		…
1913	Libev can (and often is) directly embedded into host	2226	Libev can (and often is) directly embedded into host
1914	applications. Examples of applications that embed it include the Deliantra	2227	applications. Examples of applications that embed it include the Deliantra
1915	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2228	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1916	and rxvt-unicode.	2229	and rxvt-unicode.
1917		2230
1918	The goal is to enable you to just copy the neecssary files into your	2231	The goal is to enable you to just copy the necessary files into your
1919	source directory without having to change even a single line in them, so	2232	source directory without having to change even a single line in them, so
1920	you can easily upgrade by simply copying (or having a checked-out copy of	2233	you can easily upgrade by simply copying (or having a checked-out copy of
1921	libev somewhere in your source tree).	2234	libev somewhere in your source tree).
1922		2235
1923	=head2 FILESETS	2236	=head2 FILESETS
…		…
2013		2326
2014	If defined to be C<1>, libev will try to detect the availability of the	2327	If defined to be C<1>, libev will try to detect the availability of the
2015	monotonic clock option at both compiletime and runtime. Otherwise no use	2328	monotonic clock option at both compiletime and runtime. Otherwise no use
2016	of the monotonic clock option will be attempted. If you enable this, you	2329	of the monotonic clock option will be attempted. If you enable this, you
2017	usually have to link against librt or something similar. Enabling it when	2330	usually have to link against librt or something similar. Enabling it when
2018	the functionality isn't available is safe, though, althoguh you have	2331	the functionality isn't available is safe, though, although you have
2019	to make sure you link against any libraries where the C<clock_gettime>	2332	to make sure you link against any libraries where the C<clock_gettime>
2020	function is hiding in (often F<-lrt>).	2333	function is hiding in (often F<-lrt>).
2021		2334
2022	=item EV_USE_REALTIME	2335	=item EV_USE_REALTIME
2023		2336
2024	If defined to be C<1>, libev will try to detect the availability of the	2337	If defined to be C<1>, libev will try to detect the availability of the
2025	realtime clock option at compiletime (and assume its availability at	2338	realtime clock option at compiletime (and assume its availability at
2026	runtime if successful). Otherwise no use of the realtime clock option will	2339	runtime if successful). Otherwise no use of the realtime clock option will
2027	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2340	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2028	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2341	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2029	in the description of C<EV_USE_MONOTONIC>, though.	2342	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
		2343
		2344	=item EV_USE_NANOSLEEP
		2345
		2346	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
		2347	and will use it for delays. Otherwise it will use C<select ()>.
2030		2348
2031	=item EV_USE_SELECT	2349	=item EV_USE_SELECT
2032		2350
2033	If undefined or defined to be C<1>, libev will compile in support for the	2351	If undefined or defined to be C<1>, libev will compile in support for the
2034	C<select>(2) backend. No attempt at autodetection will be done: if no	2352	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
2213		2531
2214	=item ev_set_cb (ev, cb)	2532	=item ev_set_cb (ev, cb)
2215		2533
2216	Can be used to change the callback member declaration in each watcher,	2534	Can be used to change the callback member declaration in each watcher,
2217	and the way callbacks are invoked and set. Must expand to a struct member	2535	and the way callbacks are invoked and set. Must expand to a struct member
2218	definition and a statement, respectively. See the F<ev.v> header file for	2536	definition and a statement, respectively. See the F<ev.h> header file for
2219	their default definitions. One possible use for overriding these is to	2537	their default definitions. One possible use for overriding these is to
2220	avoid the C<struct ev_loop *> as first argument in all cases, or to use	2538	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2221	method calls instead of plain function calls in C++.	2539	method calls instead of plain function calls in C++.
		2540
		2541	=head2 EXPORTED API SYMBOLS
		2542
		2543	If you need to re-export the API (e.g. via a dll) and you need a list of
		2544	exported symbols, you can use the provided F<Symbol.*> files which list
		2545	all public symbols, one per line:
		2546
		2547	Symbols.ev for libev proper
		2548	Symbols.event for the libevent emulation
		2549
		2550	This can also be used to rename all public symbols to avoid clashes with
		2551	multiple versions of libev linked together (which is obviously bad in
		2552	itself, but sometimes it is inconvinient to avoid this).
		2553
		2554	A sed command like this will create wrapper C<#define>'s that you need to
		2555	include before including F<ev.h>:
		2556
		2557	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2558
		2559	This would create a file F<wrap.h> which essentially looks like this:
		2560
		2561	#define ev_backend myprefix_ev_backend
		2562	#define ev_check_start myprefix_ev_check_start
		2563	#define ev_check_stop myprefix_ev_check_stop
		2564	...
2222		2565
2223	=head2 EXAMPLES	2566	=head2 EXAMPLES
2224		2567
2225	For a real-world example of a program the includes libev	2568	For a real-world example of a program the includes libev
2226	verbatim, you can have a look at the EV perl module	2569	verbatim, you can have a look at the EV perl module
…		…
2255		2598
2256	In this section the complexities of (many of) the algorithms used inside	2599	In this section the complexities of (many of) the algorithms used inside
2257	libev will be explained. For complexity discussions about backends see the	2600	libev will be explained. For complexity discussions about backends see the
2258	documentation for C<ev_default_init>.	2601	documentation for C<ev_default_init>.
2259		2602
		2603	All of the following are about amortised time: If an array needs to be
		2604	extended, libev needs to realloc and move the whole array, but this
		2605	happens asymptotically never with higher number of elements, so O(1) might
		2606	mean it might do a lengthy realloc operation in rare cases, but on average
		2607	it is much faster and asymptotically approaches constant time.
		2608
2260	=over 4	2609	=over 4
2261		2610
2262	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2611	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2263		2612
2264	This means that, when you have a watcher that triggers in one hour and	2613	This means that, when you have a watcher that triggers in one hour and
…		…
2270	That means that for changing a timer costs less than removing/adding them	2619	That means that for changing a timer costs less than removing/adding them
2271	as only the relative motion in the event queue has to be paid for.	2620	as only the relative motion in the event queue has to be paid for.
2272		2621
2273	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2622	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2274		2623
2275	These just add the watcher into an array or at the head of a list. If	2624	These just add the watcher into an array or at the head of a list.
2276	the array needs to be extended libev needs to realloc and move the whole
2277	array, but this happen asymptotically less and less with more watchers,
2278	thus amortised O(1).
2279
2280	=item Stopping check/prepare/idle watchers: O(1)	2625	=item Stopping check/prepare/idle watchers: O(1)
2281		2626
2282	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2627	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2283		2628
2284	These watchers are stored in lists then need to be walked to find the	2629	These watchers are stored in lists then need to be walked to find the

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Comparing libev/ev.pod (file contents): Revision 1.69 by root, Fri Dec 7 19:15:39 2007 UTC vs. Revision 1.99 by root, Sat Dec 22 06:16:36 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.69 by root, Fri Dec 7 19:15:39 2007 UTC vs.
Revision 1.99 by root, Sat Dec 22 06:16:36 2007 UTC