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

Comparing libev/ev.pod (file contents):
Revision 1.66 by root, Mon Dec 3 13:41:25 2007 UTC vs.
Revision 1.96 by ayin, Fri Dec 21 10:06:50 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.
…		…
304	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).	313	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
305		314
306	=item C<EVBACKEND_EPOLL> (value 4, Linux)	315	=item C<EVBACKEND_EPOLL> (value 4, Linux)
307		316
308	For few fds, this backend is a bit little slower than poll and select,	317	For few fds, this backend is a bit little slower than poll and select,
309	but it scales phenomenally better. While poll and select usually scale like	318	but it scales phenomenally better. While poll and select usually scale
310	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales	319	like O(total_fds) where n is the total number of fds (or the highest fd),
311	either O(1) or O(active_fds).	320	epoll scales either O(1) or O(active_fds). The epoll design has a number
		321	of shortcomings, such as silently dropping events in some hard-to-detect
		322	cases and rewiring a syscall per fd change, no fork support and bad
		323	support for dup:
312		324
313	While stopping and starting an I/O watcher in the same iteration will	325	While stopping, setting and starting an I/O watcher in the same iteration
314	result in some caching, there is still a syscall per such incident	326	will result in some caching, there is still a syscall per such incident
315	(because the fd could point to a different file description now), so its	327	(because the fd could point to a different file description now), so its
316	best to avoid that. Also, dup()ed file descriptors might not work very	328	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
317	well if you register events for both fds.	329	very well if you register events for both fds.
318		330
319	Please note that epoll sometimes generates spurious notifications, so you	331	Please note that epoll sometimes generates spurious notifications, so you
320	need to use non-blocking I/O or other means to avoid blocking when no data	332	need to use non-blocking I/O or other means to avoid blocking when no data
321	(or space) is available.	333	(or space) is available.
322		334
323	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	335	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
324		336
325	Kqueue deserves special mention, as at the time of this writing, it	337	Kqueue deserves special mention, as at the time of this writing, it
326	was broken on all BSDs except NetBSD (usually it doesn't work with	338	was broken on I<all> BSDs (usually it doesn't work with anything but
327	anything but sockets and pipes, except on Darwin, where of course its	339	sockets and pipes, except on Darwin, where of course it's completely
		340	useless. On NetBSD, it seems to work for all the FD types I tested, so it
328	completely useless). For this reason its not being "autodetected"	341	is used by default there). For this reason it's not being "autodetected"
329	unless you explicitly specify it explicitly in the flags (i.e. using	342	unless you explicitly specify it explicitly in the flags (i.e. using
330	C<EVBACKEND_KQUEUE>).	343	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
		344	system like NetBSD.
331		345
332	It scales in the same way as the epoll backend, but the interface to the	346	It scales in the same way as the epoll backend, but the interface to the
333	kernel is more efficient (which says nothing about its actual speed, of	347	kernel is more efficient (which says nothing about its actual speed,
334	course). While starting and stopping an I/O watcher does not cause an	348	of course). While stopping, setting and starting an I/O watcher does
335	extra syscall as with epoll, it still adds up to four event changes per	349	never cause an extra syscall as with epoll, it still adds up to two event
336	incident, so its best to avoid that.	350	changes per incident, support for C<fork ()> is very bad and it drops fds
		351	silently in similarly hard-to-detetc cases.
337		352
338	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	353	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
339		354
340	This is not implemented yet (and might never be).	355	This is not implemented yet (and might never be).
341		356
342	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	357	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
343		358
344	This uses the Solaris 10 port mechanism. As with everything on Solaris,	359	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
345	it's really slow, but it still scales very well (O(active_fds)).	360	it's really slow, but it still scales very well (O(active_fds)).
346		361
347	Please note that solaris ports can result in a lot of spurious	362	Please note that solaris event ports can deliver a lot of spurious
348	notifications, so you need to use non-blocking I/O or other means to avoid	363	notifications, so you need to use non-blocking I/O or other means to avoid
349	blocking when no data (or space) is available.	364	blocking when no data (or space) is available.
350		365
351	=item C<EVBACKEND_ALL>	366	=item C<EVBACKEND_ALL>
352		367
…		…
395	Destroys the default loop again (frees all memory and kernel state	410	Destroys the default loop again (frees all memory and kernel state
396	etc.). None of the active event watchers will be stopped in the normal	411	etc.). None of the active event watchers will be stopped in the normal
397	sense, so e.g. C<ev_is_active> might still return true. It is your	412	sense, so e.g. C<ev_is_active> might still return true. It is your
398	responsibility to either stop all watchers cleanly yoursef I<before>	413	responsibility to either stop all watchers cleanly yoursef I<before>
399	calling this function, or cope with the fact afterwards (which is usually	414	calling this function, or cope with the fact afterwards (which is usually
400	the easiest thing, youc na just ignore the watchers and/or C<free ()> them	415	the easiest thing, you can just ignore the watchers and/or C<free ()> them
401	for example).	416	for example).
		417
		418	Note that certain global state, such as signal state, will not be freed by
		419	this function, and related watchers (such as signal and child watchers)
		420	would need to be stopped manually.
		421
		422	In general it is not advisable to call this function except in the
		423	rare occasion where you really need to free e.g. the signal handling
		424	pipe fds. If you need dynamically allocated loops it is better to use
		425	C<ev_loop_new> and C<ev_loop_destroy>).
402		426
403	=item ev_loop_destroy (loop)	427	=item ev_loop_destroy (loop)
404		428
405	Like C<ev_default_destroy>, but destroys an event loop created by an	429	Like C<ev_default_destroy>, but destroys an event loop created by an
406	earlier call to C<ev_loop_new>.	430	earlier call to C<ev_loop_new>.
…		…
451		475
452	Returns the current "event loop time", which is the time the event loop	476	Returns the current "event loop time", which is the time the event loop
453	received events and started processing them. This timestamp does not	477	received events and started processing them. This timestamp does not
454	change as long as callbacks are being processed, and this is also the base	478	change as long as callbacks are being processed, and this is also the base
455	time used for relative timers. You can treat it as the timestamp of the	479	time used for relative timers. You can treat it as the timestamp of the
456	event occuring (or more correctly, libev finding out about it).	480	event occurring (or more correctly, libev finding out about it).
457		481
458	=item ev_loop (loop, int flags)	482	=item ev_loop (loop, int flags)
459		483
460	Finally, this is it, the event handler. This function usually is called	484	Finally, this is it, the event handler. This function usually is called
461	after you initialised all your watchers and you want to start handling	485	after you initialised all your watchers and you want to start handling
…		…
482	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	506	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
483	usually a better approach for this kind of thing.	507	usually a better approach for this kind of thing.
484		508
485	Here are the gory details of what C<ev_loop> does:	509	Here are the gory details of what C<ev_loop> does:
486		510
		511	- Before the first iteration, call any pending watchers.
487	* If there are no active watchers (reference count is zero), return.	512	* If there are no active watchers (reference count is zero), return.
488	- Queue prepare watchers and then call all outstanding watchers.	513	- Queue all prepare watchers and then call all outstanding watchers.
489	- If we have been forked, recreate the kernel state.	514	- If we have been forked, recreate the kernel state.
490	- Update the kernel state with all outstanding changes.	515	- Update the kernel state with all outstanding changes.
491	- Update the "event loop time".	516	- Update the "event loop time".
492	- Calculate for how long to block.	517	- Calculate for how long to block.
493	- Block the process, waiting for any events.	518	- Block the process, waiting for any events.
…		…
732	=item bool ev_is_pending (ev_TYPE *watcher)	757	=item bool ev_is_pending (ev_TYPE *watcher)
733		758
734	Returns a true value iff the watcher is pending, (i.e. it has outstanding	759	Returns a true value iff the watcher is pending, (i.e. it has outstanding
735	events but its callback has not yet been invoked). As long as a watcher	760	events but its callback has not yet been invoked). As long as a watcher
736	is pending (but not active) you must not call an init function on it (but	761	is pending (but not active) you must not call an init function on it (but
737	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	762	C<ev_TYPE_set> is safe), you must not change its priority, and you must
738	libev (e.g. you cnanot C<free ()> it).	763	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		764	it).
739		765
740	=item callback ev_cb (ev_TYPE *watcher)	766	=item callback ev_cb (ev_TYPE *watcher)
741		767
742	Returns the callback currently set on the watcher.	768	Returns the callback currently set on the watcher.
743		769
744	=item ev_cb_set (ev_TYPE *watcher, callback)	770	=item ev_cb_set (ev_TYPE *watcher, callback)
745		771
746	Change the callback. You can change the callback at virtually any time	772	Change the callback. You can change the callback at virtually any time
747	(modulo threads).	773	(modulo threads).
		774
		775	=item ev_set_priority (ev_TYPE *watcher, priority)
		776
		777	=item int ev_priority (ev_TYPE *watcher)
		778
		779	Set and query the priority of the watcher. The priority is a small
		780	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		781	(default: C<-2>). Pending watchers with higher priority will be invoked
		782	before watchers with lower priority, but priority will not keep watchers
		783	from being executed (except for C<ev_idle> watchers).
		784
		785	This means that priorities are I<only> used for ordering callback
		786	invocation after new events have been received. This is useful, for
		787	example, to reduce latency after idling, or more often, to bind two
		788	watchers on the same event and make sure one is called first.
		789
		790	If you need to suppress invocation when higher priority events are pending
		791	you need to look at C<ev_idle> watchers, which provide this functionality.
		792
		793	You I<must not> change the priority of a watcher as long as it is active or
		794	pending.
		795
		796	The default priority used by watchers when no priority has been set is
		797	always C<0>, which is supposed to not be too high and not be too low :).
		798
		799	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		800	fine, as long as you do not mind that the priority value you query might
		801	or might not have been adjusted to be within valid range.
		802
		803	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		804
		805	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		806	C<loop> nor C<revents> need to be valid as long as the watcher callback
		807	can deal with that fact.
		808
		809	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		810
		811	If the watcher is pending, this function returns clears its pending status
		812	and returns its C<revents> bitset (as if its callback was invoked). If the
		813	watcher isn't pending it does nothing and returns C<0>.
748		814
749	=back	815	=back
750		816
751		817
752	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	818	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
858	it is best to always use non-blocking I/O: An extra C<read>(2) returning	924	it is best to always use non-blocking I/O: An extra C<read>(2) returning
859	C<EAGAIN> is far preferable to a program hanging until some data arrives.	925	C<EAGAIN> is far preferable to a program hanging until some data arrives.
860		926
861	If you cannot run the fd in non-blocking mode (for example you should not	927	If you cannot run the fd in non-blocking mode (for example you should not
862	play around with an Xlib connection), then you have to seperately re-test	928	play around with an Xlib connection), then you have to seperately re-test
863	wether a file descriptor is really ready with a known-to-be good interface	929	whether a file descriptor is really ready with a known-to-be good interface
864	such as poll (fortunately in our Xlib example, Xlib already does this on	930	such as poll (fortunately in our Xlib example, Xlib already does this on
865	its own, so its quite safe to use).	931	its own, so its quite safe to use).
		932
		933	=head3 The special problem of disappearing file descriptors
		934
		935	Some backends (e.g. kqueue, epoll) need to be told about closing a file
		936	descriptor (either by calling C<close> explicitly or by any other means,
		937	such as C<dup>). The reason is that you register interest in some file
		938	descriptor, but when it goes away, the operating system will silently drop
		939	this interest. If another file descriptor with the same number then is
		940	registered with libev, there is no efficient way to see that this is, in
		941	fact, a different file descriptor.
		942
		943	To avoid having to explicitly tell libev about such cases, libev follows
		944	the following policy: Each time C<ev_io_set> is being called, libev
		945	will assume that this is potentially a new file descriptor, otherwise
		946	it is assumed that the file descriptor stays the same. That means that
		947	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		948	descriptor even if the file descriptor number itself did not change.
		949
		950	This is how one would do it normally anyway, the important point is that
		951	the libev application should not optimise around libev but should leave
		952	optimisations to libev.
		953
		954	=head3 The special problem of dup'ed file descriptors
		955
		956	Some backends (e.g. epoll), cannot register events for file descriptors,
		957	but only events for the underlying file descriptions. That menas when you
		958	have C<dup ()>'ed file descriptors and register events for them, only one
		959	file descriptor might actually receive events.
		960
		961	There is no workaorund possible except not registering events
		962	for potentially C<dup ()>'ed file descriptors or to resort to
		963	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
		964
		965	=head3 The special problem of fork
		966
		967	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
		968	useless behaviour. Libev fully supports fork, but needs to be told about
		969	it in the child.
		970
		971	To support fork in your programs, you either have to call
		972	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
		973	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
		974	C<EVBACKEND_POLL>.
		975
		976
		977	=head3 Watcher-Specific Functions
866		978
867	=over 4	979	=over 4
868		980
869	=item ev_io_init (ev_io *, callback, int fd, int events)	981	=item ev_io_init (ev_io *, callback, int fd, int events)
870		982
…		…
923	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1035	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
924		1036
925	The callback is guarenteed to be invoked only when its timeout has passed,	1037	The callback is guarenteed to be invoked only when its timeout has passed,
926	but if multiple timers become ready during the same loop iteration then	1038	but if multiple timers become ready during the same loop iteration then
927	order of execution is undefined.	1039	order of execution is undefined.
		1040
		1041	=head3 Watcher-Specific Functions and Data Members
928		1042
929	=over 4	1043	=over 4
930		1044
931	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1045	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
932		1046
…		…
1028	but on wallclock time (absolute time). You can tell a periodic watcher	1142	but on wallclock time (absolute time). You can tell a periodic watcher
1029	to trigger "at" some specific point in time. For example, if you tell a	1143	to trigger "at" some specific point in time. For example, if you tell a
1030	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1144	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
1031	+ 10.>) and then reset your system clock to the last year, then it will	1145	+ 10.>) and then reset your system clock to the last year, then it will
1032	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1146	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
1033	roughly 10 seconds later and of course not if you reset your system time	1147	roughly 10 seconds later).
1034	again).
1035		1148
1036	They can also be used to implement vastly more complex timers, such as	1149	They can also be used to implement vastly more complex timers, such as
1037	triggering an event on eahc midnight, local time.	1150	triggering an event on each midnight, local time or other, complicated,
		1151	rules.
1038		1152
1039	As with timers, the callback is guarenteed to be invoked only when the	1153	As with timers, the callback is guarenteed to be invoked only when the
1040	time (C<at>) has been passed, but if multiple periodic timers become ready	1154	time (C<at>) has been passed, but if multiple periodic timers become ready
1041	during the same loop iteration then order of execution is undefined.	1155	during the same loop iteration then order of execution is undefined.
1042		1156
		1157	=head3 Watcher-Specific Functions and Data Members
		1158
1043	=over 4	1159	=over 4
1044		1160
1045	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1161	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
1046		1162
1047	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1163	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
1049	Lots of arguments, lets sort it out... There are basically three modes of	1165	Lots of arguments, lets sort it out... There are basically three modes of
1050	operation, and we will explain them from simplest to complex:	1166	operation, and we will explain them from simplest to complex:
1051		1167
1052	=over 4	1168	=over 4
1053		1169
1054	=item * absolute timer (interval = reschedule_cb = 0)	1170	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1055		1171
1056	In this configuration the watcher triggers an event at the wallclock time	1172	In this configuration the watcher triggers an event at the wallclock time
1057	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1173	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
1058	that is, if it is to be run at January 1st 2011 then it will run when the	1174	that is, if it is to be run at January 1st 2011 then it will run when the
1059	system time reaches or surpasses this time.	1175	system time reaches or surpasses this time.
1060		1176
1061	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1177	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1062		1178
1063	In this mode the watcher will always be scheduled to time out at the next	1179	In this mode the watcher will always be scheduled to time out at the next
1064	C<at + N * interval> time (for some integer N) and then repeat, regardless	1180	C<at + N * interval> time (for some integer N, which can also be negative)
1065	of any time jumps.	1181	and then repeat, regardless of any time jumps.
1066		1182
1067	This can be used to create timers that do not drift with respect to system	1183	This can be used to create timers that do not drift with respect to system
1068	time:	1184	time:
1069		1185
1070	ev_periodic_set (&periodic, 0., 3600., 0);	1186	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1076		1192
1077	Another way to think about it (for the mathematically inclined) is that	1193	Another way to think about it (for the mathematically inclined) is that
1078	C<ev_periodic> will try to run the callback in this mode at the next possible	1194	C<ev_periodic> will try to run the callback in this mode at the next possible
1079	time where C<time = at (mod interval)>, regardless of any time jumps.	1195	time where C<time = at (mod interval)>, regardless of any time jumps.
1080		1196
		1197	For numerical stability it is preferable that the C<at> value is near
		1198	C<ev_now ()> (the current time), but there is no range requirement for
		1199	this value.
		1200
1081	=item * manual reschedule mode (reschedule_cb = callback)	1201	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1082		1202
1083	In this mode the values for C<interval> and C<at> are both being	1203	In this mode the values for C<interval> and C<at> are both being
1084	ignored. Instead, each time the periodic watcher gets scheduled, the	1204	ignored. Instead, each time the periodic watcher gets scheduled, the
1085	reschedule callback will be called with the watcher as first, and the	1205	reschedule callback will be called with the watcher as first, and the
1086	current time as second argument.	1206	current time as second argument.
1087		1207
1088	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1208	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1089	ever, or make any event loop modifications>. If you need to stop it,	1209	ever, or make any event loop modifications>. If you need to stop it,
1090	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1210	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1091	starting a prepare watcher).	1211	starting an C<ev_prepare> watcher, which is legal).
1092		1212
1093	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	1213	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
1094	ev_tstamp now)>, e.g.:	1214	ev_tstamp now)>, e.g.:
1095		1215
1096	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1216	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
1119	Simply stops and restarts the periodic watcher again. This is only useful	1239	Simply stops and restarts the periodic watcher again. This is only useful
1120	when you changed some parameters or the reschedule callback would return	1240	when you changed some parameters or the reschedule callback would return
1121	a different time than the last time it was called (e.g. in a crond like	1241	a different time than the last time it was called (e.g. in a crond like
1122	program when the crontabs have changed).	1242	program when the crontabs have changed).
1123		1243
		1244	=item ev_tstamp offset [read-write]
		1245
		1246	When repeating, this contains the offset value, otherwise this is the
		1247	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1248
		1249	Can be modified any time, but changes only take effect when the periodic
		1250	timer fires or C<ev_periodic_again> is being called.
		1251
1124	=item ev_tstamp interval [read-write]	1252	=item ev_tstamp interval [read-write]
1125		1253
1126	The current interval value. Can be modified any time, but changes only	1254	The current interval value. Can be modified any time, but changes only
1127	take effect when the periodic timer fires or C<ev_periodic_again> is being	1255	take effect when the periodic timer fires or C<ev_periodic_again> is being
1128	called.	1256	called.
…		…
1130	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]	1258	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
1131		1259
1132	The current reschedule callback, or C<0>, if this functionality is	1260	The current reschedule callback, or C<0>, if this functionality is
1133	switched off. Can be changed any time, but changes only take effect when	1261	switched off. Can be changed any time, but changes only take effect when
1134	the periodic timer fires or C<ev_periodic_again> is being called.	1262	the periodic timer fires or C<ev_periodic_again> is being called.
		1263
		1264	=item ev_tstamp at [read-only]
		1265
		1266	When active, contains the absolute time that the watcher is supposed to
		1267	trigger next.
1135		1268
1136	=back	1269	=back
1137		1270
1138	Example: Call a callback every hour, or, more precisely, whenever the	1271	Example: Call a callback every hour, or, more precisely, whenever the
1139	system clock is divisible by 3600. The callback invocation times have	1272	system clock is divisible by 3600. The callback invocation times have
…		…
1181	with the kernel (thus it coexists with your own signal handlers as long	1314	with the kernel (thus it coexists with your own signal handlers as long
1182	as you don't register any with libev). Similarly, when the last signal	1315	as you don't register any with libev). Similarly, when the last signal
1183	watcher for a signal is stopped libev will reset the signal handler to	1316	watcher for a signal is stopped libev will reset the signal handler to
1184	SIG_DFL (regardless of what it was set to before).	1317	SIG_DFL (regardless of what it was set to before).
1185		1318
		1319	=head3 Watcher-Specific Functions and Data Members
		1320
1186	=over 4	1321	=over 4
1187		1322
1188	=item ev_signal_init (ev_signal *, callback, int signum)	1323	=item ev_signal_init (ev_signal *, callback, int signum)
1189		1324
1190	=item ev_signal_set (ev_signal *, int signum)	1325	=item ev_signal_set (ev_signal *, int signum)
…		…
1201		1336
1202	=head2 C<ev_child> - watch out for process status changes	1337	=head2 C<ev_child> - watch out for process status changes
1203		1338
1204	Child watchers trigger when your process receives a SIGCHLD in response to	1339	Child watchers trigger when your process receives a SIGCHLD in response to
1205	some child status changes (most typically when a child of yours dies).	1340	some child status changes (most typically when a child of yours dies).
		1341
		1342	=head3 Watcher-Specific Functions and Data Members
1206		1343
1207	=over 4	1344	=over 4
1208		1345
1209	=item ev_child_init (ev_child *, callback, int pid)	1346	=item ev_child_init (ev_child *, callback, int pid)
1210		1347
…		…
1278	reader). Inotify will be used to give hints only and should not change the	1415	reader). Inotify will be used to give hints only and should not change the
1279	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1416	semantics of C<ev_stat> watchers, which means that libev sometimes needs
1280	to fall back to regular polling again even with inotify, but changes are	1417	to fall back to regular polling again even with inotify, but changes are
1281	usually detected immediately, and if the file exists there will be no	1418	usually detected immediately, and if the file exists there will be no
1282	polling.	1419	polling.
		1420
		1421	=head3 Watcher-Specific Functions and Data Members
1283		1422
1284	=over 4	1423	=over 4
1285		1424
1286	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1425	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1287		1426
…		…
1351	ev_stat_start (loop, &passwd);	1490	ev_stat_start (loop, &passwd);
1352		1491
1353		1492
1354	=head2 C<ev_idle> - when you've got nothing better to do...	1493	=head2 C<ev_idle> - when you've got nothing better to do...
1355		1494
1356	Idle watchers trigger events when there are no other events are pending	1495	Idle watchers trigger events when no other events of the same or higher
1357	(prepare, check and other idle watchers do not count). That is, as long	1496	priority are pending (prepare, check and other idle watchers do not
1358	as your process is busy handling sockets or timeouts (or even signals,	1497	count).
1359	imagine) it will not be triggered. But when your process is idle all idle	1498
1360	watchers are being called again and again, once per event loop iteration -	1499	That is, as long as your process is busy handling sockets or timeouts
		1500	(or even signals, imagine) of the same or higher priority it will not be
		1501	triggered. But when your process is idle (or only lower-priority watchers
		1502	are pending), the idle watchers are being called once per event loop
1361	until stopped, that is, or your process receives more events and becomes	1503	iteration - until stopped, that is, or your process receives more events
1362	busy.	1504	and becomes busy again with higher priority stuff.
1363		1505
1364	The most noteworthy effect is that as long as any idle watchers are	1506	The most noteworthy effect is that as long as any idle watchers are
1365	active, the process will not block when waiting for new events.	1507	active, the process will not block when waiting for new events.
1366		1508
1367	Apart from keeping your process non-blocking (which is a useful	1509	Apart from keeping your process non-blocking (which is a useful
1368	effect on its own sometimes), idle watchers are a good place to do	1510	effect on its own sometimes), idle watchers are a good place to do
1369	"pseudo-background processing", or delay processing stuff to after the	1511	"pseudo-background processing", or delay processing stuff to after the
1370	event loop has handled all outstanding events.	1512	event loop has handled all outstanding events.
		1513
		1514	=head3 Watcher-Specific Functions and Data Members
1371		1515
1372	=over 4	1516	=over 4
1373		1517
1374	=item ev_idle_init (ev_signal *, callback)	1518	=item ev_idle_init (ev_signal *, callback)
1375		1519
…		…
1433	with priority higher than or equal to the event loop and one coroutine	1577	with priority higher than or equal to the event loop and one coroutine
1434	of lower priority, but only once, using idle watchers to keep the event	1578	of lower priority, but only once, using idle watchers to keep the event
1435	loop from blocking if lower-priority coroutines are active, thus mapping	1579	loop from blocking if lower-priority coroutines are active, thus mapping
1436	low-priority coroutines to idle/background tasks).	1580	low-priority coroutines to idle/background tasks).
1437		1581
		1582	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1583	priority, to ensure that they are being run before any other watchers
		1584	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1585	too) should not activate ("feed") events into libev. While libev fully
		1586	supports this, they will be called before other C<ev_check> watchers did
		1587	their job. As C<ev_check> watchers are often used to embed other event
		1588	loops those other event loops might be in an unusable state until their
		1589	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1590	others).
		1591
		1592	=head3 Watcher-Specific Functions and Data Members
		1593
1438	=over 4	1594	=over 4
1439		1595
1440	=item ev_prepare_init (ev_prepare *, callback)	1596	=item ev_prepare_init (ev_prepare *, callback)
1441		1597
1442	=item ev_check_init (ev_check *, callback)	1598	=item ev_check_init (ev_check *, callback)
…		…
1445	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1601	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1446	macros, but using them is utterly, utterly and completely pointless.	1602	macros, but using them is utterly, utterly and completely pointless.
1447		1603
1448	=back	1604	=back
1449		1605
1450	Example: To include a library such as adns, you would add IO watchers	1606	There are a number of principal ways to embed other event loops or modules
1451	and a timeout watcher in a prepare handler, as required by libadns, and	1607	into libev. Here are some ideas on how to include libadns into libev
		1608	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1609	use for an actually working example. Another Perl module named C<EV::Glib>
		1610	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1611	into the Glib event loop).
		1612
		1613	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1452	in a check watcher, destroy them and call into libadns. What follows is	1614	and in a check watcher, destroy them and call into libadns. What follows
1453	pseudo-code only of course:	1615	is pseudo-code only of course. This requires you to either use a low
		1616	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1617	the callbacks for the IO/timeout watchers might not have been called yet.
1454		1618
1455	static ev_io iow [nfd];	1619	static ev_io iow [nfd];
1456	static ev_timer tw;	1620	static ev_timer tw;
1457		1621
1458	static void	1622	static void
1459	io_cb (ev_loop loop, ev_io w, int revents)	1623	io_cb (ev_loop loop, ev_io w, int revents)
1460	{	1624	{
1461	// set the relevant poll flags
1462	// could also call adns_processreadable etc. here
1463	struct pollfd fd = (struct pollfd )w->data;
1464	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1465	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1466	}	1625	}
1467		1626
1468	// create io watchers for each fd and a timer before blocking	1627	// create io watchers for each fd and a timer before blocking
1469	static void	1628	static void
1470	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1629	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
…		…
1476		1635
1477	/* the callback is illegal, but won't be called as we stop during check */	1636	/* the callback is illegal, but won't be called as we stop during check */
1478	ev_timer_init (&tw, 0, timeout * 1e-3);	1637	ev_timer_init (&tw, 0, timeout * 1e-3);
1479	ev_timer_start (loop, &tw);	1638	ev_timer_start (loop, &tw);
1480		1639
1481	// create on ev_io per pollfd	1640	// create one ev_io per pollfd
1482	for (int i = 0; i < nfd; ++i)	1641	for (int i = 0; i < nfd; ++i)
1483	{	1642	{
1484	ev_io_init (iow + i, io_cb, fds [i].fd,	1643	ev_io_init (iow + i, io_cb, fds [i].fd,
1485	((fds [i].events & POLLIN ? EV_READ : 0)	1644	((fds [i].events & POLLIN ? EV_READ : 0)
1486	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1645	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1487		1646
1488	fds [i].revents = 0;	1647	fds [i].revents = 0;
1489	iow [i].data = fds + i;
1490	ev_io_start (loop, iow + i);	1648	ev_io_start (loop, iow + i);
1491	}	1649	}
1492	}	1650	}
1493		1651
1494	// stop all watchers after blocking	1652	// stop all watchers after blocking
…		…
1496	adns_check_cb (ev_loop loop, ev_check w, int revents)	1654	adns_check_cb (ev_loop loop, ev_check w, int revents)
1497	{	1655	{
1498	ev_timer_stop (loop, &tw);	1656	ev_timer_stop (loop, &tw);
1499		1657
1500	for (int i = 0; i < nfd; ++i)	1658	for (int i = 0; i < nfd; ++i)
		1659	{
		1660	// set the relevant poll flags
		1661	// could also call adns_processreadable etc. here
		1662	struct pollfd *fd = fds + i;
		1663	int revents = ev_clear_pending (iow + i);
		1664	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1665	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1666
		1667	// now stop the watcher
1501	ev_io_stop (loop, iow + i);	1668	ev_io_stop (loop, iow + i);
		1669	}
1502		1670
1503	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1671	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1672	}
		1673
		1674	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1675	in the prepare watcher and would dispose of the check watcher.
		1676
		1677	Method 3: If the module to be embedded supports explicit event
		1678	notification (adns does), you can also make use of the actual watcher
		1679	callbacks, and only destroy/create the watchers in the prepare watcher.
		1680
		1681	static void
		1682	timer_cb (EV_P_ ev_timer *w, int revents)
		1683	{
		1684	adns_state ads = (adns_state)w->data;
		1685	update_now (EV_A);
		1686
		1687	adns_processtimeouts (ads, &tv_now);
		1688	}
		1689
		1690	static void
		1691	io_cb (EV_P_ ev_io *w, int revents)
		1692	{
		1693	adns_state ads = (adns_state)w->data;
		1694	update_now (EV_A);
		1695
		1696	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1697	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1698	}
		1699
		1700	// do not ever call adns_afterpoll
		1701
		1702	Method 4: Do not use a prepare or check watcher because the module you
		1703	want to embed is too inflexible to support it. Instead, youc na override
		1704	their poll function. The drawback with this solution is that the main
		1705	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1706	this.
		1707
		1708	static gint
		1709	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1710	{
		1711	int got_events = 0;
		1712
		1713	for (n = 0; n < nfds; ++n)
		1714	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1715
		1716	if (timeout >= 0)
		1717	// create/start timer
		1718
		1719	// poll
		1720	ev_loop (EV_A_ 0);
		1721
		1722	// stop timer again
		1723	if (timeout >= 0)
		1724	ev_timer_stop (EV_A_ &to);
		1725
		1726	// stop io watchers again - their callbacks should have set
		1727	for (n = 0; n < nfds; ++n)
		1728	ev_io_stop (EV_A_ iow [n]);
		1729
		1730	return got_events;
1504	}	1731	}
1505		1732
1506		1733
1507	=head2 C<ev_embed> - when one backend isn't enough...	1734	=head2 C<ev_embed> - when one backend isn't enough...
1508		1735
1509	This is a rather advanced watcher type that lets you embed one event loop	1736	This is a rather advanced watcher type that lets you embed one event loop
1510	into another (currently only C<ev_io> events are supported in the embedded	1737	into another (currently only C<ev_io> events are supported in the embedded
1511	loop, other types of watchers might be handled in a delayed or incorrect	1738	loop, other types of watchers might be handled in a delayed or incorrect
1512	fashion and must not be used).	1739	fashion and must not be used). (See portability notes, below).
1513		1740
1514	There are primarily two reasons you would want that: work around bugs and	1741	There are primarily two reasons you would want that: work around bugs and
1515	prioritise I/O.	1742	prioritise I/O.
1516		1743
1517	As an example for a bug workaround, the kqueue backend might only support	1744	As an example for a bug workaround, the kqueue backend might only support
…		…
1572	ev_embed_start (loop_hi, &embed);	1799	ev_embed_start (loop_hi, &embed);
1573	}	1800	}
1574	else	1801	else
1575	loop_lo = loop_hi;	1802	loop_lo = loop_hi;
1576		1803
		1804	=head2 Portability notes
		1805
		1806	Kqueue is nominally embeddable, but this is broken on all BSDs that I
		1807	tried, in various ways. Usually the embedded event loop will simply never
		1808	receive events, sometimes it will only trigger a few times, sometimes in a
		1809	loop. Epoll is also nominally embeddable, but many Linux kernel versions
		1810	will always eport the epoll fd as ready, even when no events are pending.
		1811
		1812	While libev allows embedding these backends (they are contained in
		1813	C<ev_embeddable_backends ()>), take extreme care that it will actually
		1814	work.
		1815
		1816	When in doubt, create a dynamic event loop forced to use sockets (this
		1817	usually works) and possibly another thread and a pipe or so to report to
		1818	your main event loop.
		1819
		1820	=head3 Watcher-Specific Functions and Data Members
		1821
1577	=over 4	1822	=over 4
1578		1823
1579	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)	1824	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)
1580		1825
1581	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)	1826	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)
…		…
1590		1835
1591	Make a single, non-blocking sweep over the embedded loop. This works	1836	Make a single, non-blocking sweep over the embedded loop. This works
1592	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1837	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1593	apropriate way for embedded loops.	1838	apropriate way for embedded loops.
1594		1839
1595	=item struct ev_loop *loop [read-only]	1840	=item struct ev_loop *other [read-only]
1596		1841
1597	The embedded event loop.	1842	The embedded event loop.
1598		1843
1599	=back	1844	=back
1600		1845
…		…
1607	event loop blocks next and before C<ev_check> watchers are being called,	1852	event loop blocks next and before C<ev_check> watchers are being called,
1608	and only in the child after the fork. If whoever good citizen calling	1853	and only in the child after the fork. If whoever good citizen calling
1609	C<ev_default_fork> cheats and calls it in the wrong process, the fork	1854	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1610	handlers will be invoked, too, of course.	1855	handlers will be invoked, too, of course.
1611		1856
		1857	=head3 Watcher-Specific Functions and Data Members
		1858
1612	=over 4	1859	=over 4
1613		1860
1614	=item ev_fork_init (ev_signal *, callback)	1861	=item ev_fork_init (ev_signal *, callback)
1615		1862
1616	Initialises and configures the fork watcher - it has no parameters of any	1863	Initialises and configures the fork watcher - it has no parameters of any
…		…
1712		1959
1713	To use it,	1960	To use it,
1714		1961
1715	#include <ev++.h>	1962	#include <ev++.h>
1716		1963
1717	(it is not installed by default). This automatically includes F<ev.h>	1964	This automatically includes F<ev.h> and puts all of its definitions (many
1718	and puts all of its definitions (many of them macros) into the global	1965	of them macros) into the global namespace. All C++ specific things are
1719	namespace. All C++ specific things are put into the C<ev> namespace.	1966	put into the C<ev> namespace. It should support all the same embedding
		1967	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1720		1968
1721	It should support all the same embedding options as F<ev.h>, most notably	1969	Care has been taken to keep the overhead low. The only data member the C++
1722	C<EV_MULTIPLICITY>.	1970	classes add (compared to plain C-style watchers) is the event loop pointer
		1971	that the watcher is associated with (or no additional members at all if
		1972	you disable C<EV_MULTIPLICITY> when embedding libev).
		1973
		1974	Currently, functions, and static and non-static member functions can be
		1975	used as callbacks. Other types should be easy to add as long as they only
		1976	need one additional pointer for context. If you need support for other
		1977	types of functors please contact the author (preferably after implementing
		1978	it).
1723		1979
1724	Here is a list of things available in the C<ev> namespace:	1980	Here is a list of things available in the C<ev> namespace:
1725		1981
1726	=over 4	1982	=over 4
1727		1983
…		…
1743		1999
1744	All of those classes have these methods:	2000	All of those classes have these methods:
1745		2001
1746	=over 4	2002	=over 4
1747		2003
1748	=item ev::TYPE::TYPE (object , object::method )	2004	=item ev::TYPE::TYPE ()
1749		2005
1750	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	2006	=item ev::TYPE::TYPE (struct ev_loop *)
1751		2007
1752	=item ev::TYPE::~TYPE	2008	=item ev::TYPE::~TYPE
1753		2009
1754	The constructor takes a pointer to an object and a method pointer to	2010	The constructor (optionally) takes an event loop to associate the watcher
1755	the event handler callback to call in this class. The constructor calls	2011	with. If it is omitted, it will use C<EV_DEFAULT>.
1756	C<ev_init> for you, which means you have to call the C<set> method	2012
1757	before starting it. If you do not specify a loop then the constructor	2013	The constructor calls C<ev_init> for you, which means you have to call the
1758	automatically associates the default loop with this watcher.	2014	C<set> method before starting it.
		2015
		2016	It will not set a callback, however: You have to call the templated C<set>
		2017	method to set a callback before you can start the watcher.
		2018
		2019	(The reason why you have to use a method is a limitation in C++ which does
		2020	not allow explicit template arguments for constructors).
1759		2021
1760	The destructor automatically stops the watcher if it is active.	2022	The destructor automatically stops the watcher if it is active.
		2023
		2024	=item w->set<class, &class::method> (object *)
		2025
		2026	This method sets the callback method to call. The method has to have a
		2027	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		2028	first argument and the C<revents> as second. The object must be given as
		2029	parameter and is stored in the C<data> member of the watcher.
		2030
		2031	This method synthesizes efficient thunking code to call your method from
		2032	the C callback that libev requires. If your compiler can inline your
		2033	callback (i.e. it is visible to it at the place of the C<set> call and
		2034	your compiler is good :), then the method will be fully inlined into the
		2035	thunking function, making it as fast as a direct C callback.
		2036
		2037	Example: simple class declaration and watcher initialisation
		2038
		2039	struct myclass
		2040	{
		2041	void io_cb (ev::io &w, int revents) { }
		2042	}
		2043
		2044	myclass obj;
		2045	ev::io iow;
		2046	iow.set <myclass, &myclass::io_cb> (&obj);
		2047
		2048	=item w->set<function> (void *data = 0)
		2049
		2050	Also sets a callback, but uses a static method or plain function as
		2051	callback. The optional C<data> argument will be stored in the watcher's
		2052	C<data> member and is free for you to use.
		2053
		2054	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2055
		2056	See the method-C<set> above for more details.
		2057
		2058	Example:
		2059
		2060	static void io_cb (ev::io &w, int revents) { }
		2061	iow.set <io_cb> ();
1761		2062
1762	=item w->set (struct ev_loop *)	2063	=item w->set (struct ev_loop *)
1763		2064
1764	Associates a different C<struct ev_loop> with this watcher. You can only	2065	Associates a different C<struct ev_loop> with this watcher. You can only
1765	do this when the watcher is inactive (and not pending either).	2066	do this when the watcher is inactive (and not pending either).
1766		2067
1767	=item w->set ([args])	2068	=item w->set ([args])
1768		2069
1769	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2070	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1770	called at least once. Unlike the C counterpart, an active watcher gets	2071	called at least once. Unlike the C counterpart, an active watcher gets
1771	automatically stopped and restarted.	2072	automatically stopped and restarted when reconfiguring it with this
		2073	method.
1772		2074
1773	=item w->start ()	2075	=item w->start ()
1774		2076
1775	Starts the watcher. Note that there is no C<loop> argument as the	2077	Starts the watcher. Note that there is no C<loop> argument, as the
1776	constructor already takes the loop.	2078	constructor already stores the event loop.
1777		2079
1778	=item w->stop ()	2080	=item w->stop ()
1779		2081
1780	Stops the watcher if it is active. Again, no C<loop> argument.	2082	Stops the watcher if it is active. Again, no C<loop> argument.
1781		2083
1782	=item w->again () C<ev::timer>, C<ev::periodic> only	2084	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1783		2085
1784	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2086	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1785	C<ev_TYPE_again> function.	2087	C<ev_TYPE_again> function.
1786		2088
1787	=item w->sweep () C<ev::embed> only	2089	=item w->sweep () (C<ev::embed> only)
1788		2090
1789	Invokes C<ev_embed_sweep>.	2091	Invokes C<ev_embed_sweep>.
1790		2092
1791	=item w->update () C<ev::stat> only	2093	=item w->update () (C<ev::stat> only)
1792		2094
1793	Invokes C<ev_stat_stat>.	2095	Invokes C<ev_stat_stat>.
1794		2096
1795	=back	2097	=back
1796		2098
…		…
1806		2108
1807	myclass ();	2109	myclass ();
1808	}	2110	}
1809		2111
1810	myclass::myclass (int fd)	2112	myclass::myclass (int fd)
1811	: io (this, &myclass::io_cb),
1812	idle (this, &myclass::idle_cb)
1813	{	2113	{
		2114	io .set <myclass, &myclass::io_cb > (this);
		2115	idle.set <myclass, &myclass::idle_cb> (this);
		2116
1814	io.start (fd, ev::READ);	2117	io.start (fd, ev::READ);
1815	}	2118	}
1816		2119
1817		2120
1818	=head1 MACRO MAGIC	2121	=head1 MACRO MAGIC
1819		2122
1820	Libev can be compiled with a variety of options, the most fundemantal is	2123	Libev can be compiled with a variety of options, the most fundamantal
1821	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2124	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1822	callbacks have an initial C<struct ev_loop *> argument.	2125	functions and callbacks have an initial C<struct ev_loop *> argument.
1823		2126
1824	To make it easier to write programs that cope with either variant, the	2127	To make it easier to write programs that cope with either variant, the
1825	following macros are defined:	2128	following macros are defined:
1826		2129
1827	=over 4	2130	=over 4
…		…
1860	loop, if multiple loops are supported ("ev loop default").	2163	loop, if multiple loops are supported ("ev loop default").
1861		2164
1862	=back	2165	=back
1863		2166
1864	Example: Declare and initialise a check watcher, utilising the above	2167	Example: Declare and initialise a check watcher, utilising the above
1865	macros so it will work regardless of wether multiple loops are supported	2168	macros so it will work regardless of whether multiple loops are supported
1866	or not.	2169	or not.
1867		2170
1868	static void	2171	static void
1869	check_cb (EV_P_ ev_timer *w, int revents)	2172	check_cb (EV_P_ ev_timer *w, int revents)
1870	{	2173	{
…		…
1881	Libev can (and often is) directly embedded into host	2184	Libev can (and often is) directly embedded into host
1882	applications. Examples of applications that embed it include the Deliantra	2185	applications. Examples of applications that embed it include the Deliantra
1883	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2186	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1884	and rxvt-unicode.	2187	and rxvt-unicode.
1885		2188
1886	The goal is to enable you to just copy the neecssary files into your	2189	The goal is to enable you to just copy the necessary files into your
1887	source directory without having to change even a single line in them, so	2190	source directory without having to change even a single line in them, so
1888	you can easily upgrade by simply copying (or having a checked-out copy of	2191	you can easily upgrade by simply copying (or having a checked-out copy of
1889	libev somewhere in your source tree).	2192	libev somewhere in your source tree).
1890		2193
1891	=head2 FILESETS	2194	=head2 FILESETS
…		…
1981		2284
1982	If defined to be C<1>, libev will try to detect the availability of the	2285	If defined to be C<1>, libev will try to detect the availability of the
1983	monotonic clock option at both compiletime and runtime. Otherwise no use	2286	monotonic clock option at both compiletime and runtime. Otherwise no use
1984	of the monotonic clock option will be attempted. If you enable this, you	2287	of the monotonic clock option will be attempted. If you enable this, you
1985	usually have to link against librt or something similar. Enabling it when	2288	usually have to link against librt or something similar. Enabling it when
1986	the functionality isn't available is safe, though, althoguh you have	2289	the functionality isn't available is safe, though, although you have
1987	to make sure you link against any libraries where the C<clock_gettime>	2290	to make sure you link against any libraries where the C<clock_gettime>
1988	function is hiding in (often F<-lrt>).	2291	function is hiding in (often F<-lrt>).
1989		2292
1990	=item EV_USE_REALTIME	2293	=item EV_USE_REALTIME
1991		2294
1992	If defined to be C<1>, libev will try to detect the availability of the	2295	If defined to be C<1>, libev will try to detect the availability of the
1993	realtime clock option at compiletime (and assume its availability at	2296	realtime clock option at compiletime (and assume its availability at
1994	runtime if successful). Otherwise no use of the realtime clock option will	2297	runtime if successful). Otherwise no use of the realtime clock option will
1995	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2298	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
1996	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2299	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
1997	in the description of C<EV_USE_MONOTONIC>, though.	2300	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
1998		2301
1999	=item EV_USE_SELECT	2302	=item EV_USE_SELECT
2000		2303
2001	If undefined or defined to be C<1>, libev will compile in support for the	2304	If undefined or defined to be C<1>, libev will compile in support for the
2002	C<select>(2) backend. No attempt at autodetection will be done: if no	2305	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
2095	will have the C<struct ev_loop *> as first argument, and you can create	2398	will have the C<struct ev_loop *> as first argument, and you can create
2096	additional independent event loops. Otherwise there will be no support	2399	additional independent event loops. Otherwise there will be no support
2097	for multiple event loops and there is no first event loop pointer	2400	for multiple event loops and there is no first event loop pointer
2098	argument. Instead, all functions act on the single default loop.	2401	argument. Instead, all functions act on the single default loop.
2099		2402
		2403	=item EV_MINPRI
		2404
		2405	=item EV_MAXPRI
		2406
		2407	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2408	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2409	provide for more priorities by overriding those symbols (usually defined
		2410	to be C<-2> and C<2>, respectively).
		2411
		2412	When doing priority-based operations, libev usually has to linearly search
		2413	all the priorities, so having many of them (hundreds) uses a lot of space
		2414	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2415	fine.
		2416
		2417	If your embedding app does not need any priorities, defining these both to
		2418	C<0> will save some memory and cpu.
		2419
2100	=item EV_PERIODIC_ENABLE	2420	=item EV_PERIODIC_ENABLE
2101		2421
2102	If undefined or defined to be C<1>, then periodic timers are supported. If	2422	If undefined or defined to be C<1>, then periodic timers are supported. If
		2423	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2424	code.
		2425
		2426	=item EV_IDLE_ENABLE
		2427
		2428	If undefined or defined to be C<1>, then idle watchers are supported. If
2103	defined to be C<0>, then they are not. Disabling them saves a few kB of	2429	defined to be C<0>, then they are not. Disabling them saves a few kB of
2104	code.	2430	code.
2105		2431
2106	=item EV_EMBED_ENABLE	2432	=item EV_EMBED_ENABLE
2107		2433
…		…
2158		2484
2159	=item ev_set_cb (ev, cb)	2485	=item ev_set_cb (ev, cb)
2160		2486
2161	Can be used to change the callback member declaration in each watcher,	2487	Can be used to change the callback member declaration in each watcher,
2162	and the way callbacks are invoked and set. Must expand to a struct member	2488	and the way callbacks are invoked and set. Must expand to a struct member
2163	definition and a statement, respectively. See the F<ev.v> header file for	2489	definition and a statement, respectively. See the F<ev.h> header file for
2164	their default definitions. One possible use for overriding these is to	2490	their default definitions. One possible use for overriding these is to
2165	avoid the C<struct ev_loop *> as first argument in all cases, or to use	2491	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2166	method calls instead of plain function calls in C++.	2492	method calls instead of plain function calls in C++.
		2493
		2494	=head2 EXPORTED API SYMBOLS
		2495
		2496	If you need to re-export the API (e.g. via a dll) and you need a list of
		2497	exported symbols, you can use the provided F<Symbol.*> files which list
		2498	all public symbols, one per line:
		2499
		2500	Symbols.ev for libev proper
		2501	Symbols.event for the libevent emulation
		2502
		2503	This can also be used to rename all public symbols to avoid clashes with
		2504	multiple versions of libev linked together (which is obviously bad in
		2505	itself, but sometimes it is inconvinient to avoid this).
		2506
		2507	A sed command like this will create wrapper C<#define>'s that you need to
		2508	include before including F<ev.h>:
		2509
		2510	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2511
		2512	This would create a file F<wrap.h> which essentially looks like this:
		2513
		2514	#define ev_backend myprefix_ev_backend
		2515	#define ev_check_start myprefix_ev_check_start
		2516	#define ev_check_stop myprefix_ev_check_stop
		2517	...
2167		2518
2168	=head2 EXAMPLES	2519	=head2 EXAMPLES
2169		2520
2170	For a real-world example of a program the includes libev	2521	For a real-world example of a program the includes libev
2171	verbatim, you can have a look at the EV perl module	2522	verbatim, you can have a look at the EV perl module
…		…
2200		2551
2201	In this section the complexities of (many of) the algorithms used inside	2552	In this section the complexities of (many of) the algorithms used inside
2202	libev will be explained. For complexity discussions about backends see the	2553	libev will be explained. For complexity discussions about backends see the
2203	documentation for C<ev_default_init>.	2554	documentation for C<ev_default_init>.
2204		2555
		2556	All of the following are about amortised time: If an array needs to be
		2557	extended, libev needs to realloc and move the whole array, but this
		2558	happens asymptotically never with higher number of elements, so O(1) might
		2559	mean it might do a lengthy realloc operation in rare cases, but on average
		2560	it is much faster and asymptotically approaches constant time.
		2561
2205	=over 4	2562	=over 4
2206		2563
2207	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2564	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2208		2565
		2566	This means that, when you have a watcher that triggers in one hour and
		2567	there are 100 watchers that would trigger before that then inserting will
		2568	have to skip those 100 watchers.
		2569
2209	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2570	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2210		2571
		2572	That means that for changing a timer costs less than removing/adding them
		2573	as only the relative motion in the event queue has to be paid for.
		2574
2211	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2575	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2212		2576
		2577	These just add the watcher into an array or at the head of a list.
2213	=item Stopping check/prepare/idle watchers: O(1)	2578	=item Stopping check/prepare/idle watchers: O(1)
2214		2579
2215	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2580	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2216		2581
		2582	These watchers are stored in lists then need to be walked to find the
		2583	correct watcher to remove. The lists are usually short (you don't usually
		2584	have many watchers waiting for the same fd or signal).
		2585
2217	=item Finding the next timer per loop iteration: O(1)	2586	=item Finding the next timer per loop iteration: O(1)
2218		2587
2219	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2588	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2220		2589
		2590	A change means an I/O watcher gets started or stopped, which requires
		2591	libev to recalculate its status (and possibly tell the kernel).
		2592
2221	=item Activating one watcher: O(1)	2593	=item Activating one watcher: O(1)
2222		2594
		2595	=item Priority handling: O(number_of_priorities)
		2596
		2597	Priorities are implemented by allocating some space for each
		2598	priority. When doing priority-based operations, libev usually has to
		2599	linearly search all the priorities.
		2600
2223	=back	2601	=back
2224		2602
2225		2603
2226	=head1 AUTHOR	2604	=head1 AUTHOR
2227		2605

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Comparing libev/ev.pod (file contents): Revision 1.66 by root, Mon Dec 3 13:41:25 2007 UTC vs. Revision 1.96 by ayin, Fri Dec 21 10:06:50 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.66 by root, Mon Dec 3 13:41:25 2007 UTC vs.
Revision 1.96 by ayin, Fri Dec 21 10:06:50 2007 UTC