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

Comparing libev/ev.pod (file contents):
Revision 1.61 by root, Thu Nov 29 12:21:05 2007 UTC vs.
Revision 1.98 by root, Sat Dec 22 06:10:25 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.
…		…
109		115
110	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
111	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
112	you actually want to know.	118	you actually want to know.
113		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
114	=item int ev_version_major ()	126	=item int ev_version_major ()
115		127
116	=item int ev_version_minor ()	128	=item int ev_version_minor ()
117		129
118	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
119	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
120	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
121	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
122	version of the library your program was compiled against.	134	version of the library your program was compiled against.
123		135
		136	These version numbers refer to the ABI version of the library, not the
		137	release version.
		138
124	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,
125	as this indicates an incompatible change. Minor versions are usually	140	as this indicates an incompatible change. Minor versions are usually
126	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
127	not a problem.	142	not a problem.
128		143
129	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
130	version.	145	version.
…		…
266	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	281	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
267	override the flags completely if it is found in the environment. This is	282	override the flags completely if it is found in the environment. This is
268	useful to try out specific backends to test their performance, or to work	283	useful to try out specific backends to test their performance, or to work
269	around bugs.	284	around bugs.
270		285
		286	=item C<EVFLAG_FORKCHECK>
		287
		288	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		289	a fork, you can also make libev check for a fork in each iteration by
		290	enabling this flag.
		291
		292	This works by calling C<getpid ()> on every iteration of the loop,
		293	and thus this might slow down your event loop if you do a lot of loop
		294	iterations and little real work, but is usually not noticeable (on my
		295	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		296	without a syscall and thus I<very> fast, but my Linux system also has
		297	C<pthread_atfork> which is even faster).
		298
		299	The big advantage of this flag is that you can forget about fork (and
		300	forget about forgetting to tell libev about forking) when you use this
		301	flag.
		302
		303	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		304	environment variable.
		305
271	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	306	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
272		307
273	This is your standard select(2) backend. Not I<completely> standard, as	308	This is your standard select(2) backend. Not I<completely> standard, as
274	libev tries to roll its own fd_set with no limits on the number of fds,	309	libev tries to roll its own fd_set with no limits on the number of fds,
275	but if that fails, expect a fairly low limit on the number of fds when	310	but if that fails, expect a fairly low limit on the number of fds when
…		…
284	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).
285		320
286	=item C<EVBACKEND_EPOLL> (value 4, Linux)	321	=item C<EVBACKEND_EPOLL> (value 4, Linux)
287		322
288	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,
289	but it scales phenomenally better. While poll and select usually scale like	324	but it scales phenomenally better. While poll and select usually scale
290	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),
291	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:
292		330
293	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
294	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
295	(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
296	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
297	well if you register events for both fds.	335	very well if you register events for both fds.
298		336
299	Please note that epoll sometimes generates spurious notifications, so you	337	Please note that epoll sometimes generates spurious notifications, so you
300	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
301	(or space) is available.	339	(or space) is available.
302		340
303	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	341	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
304		342
305	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
306	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
307	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
308	completely useless). For this reason its not being "autodetected"	347	is used by default there). For this reason it's not being "autodetected"
309	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
310	C<EVBACKEND_KQUEUE>).	349	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
		350	system like NetBSD.
311		351
312	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
313	kernel is more efficient (which says nothing about its actual speed, of	353	kernel is more efficient (which says nothing about its actual speed,
314	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
315	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
316	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.
317		358
318	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	359	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
319		360
320	This is not implemented yet (and might never be).	361	This is not implemented yet (and might never be).
321		362
322	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	363	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
323		364
324	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,
325	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)).
326		367
327	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
328	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
329	blocking when no data (or space) is available.	370	blocking when no data (or space) is available.
330		371
331	=item C<EVBACKEND_ALL>	372	=item C<EVBACKEND_ALL>
332		373
…		…
375	Destroys the default loop again (frees all memory and kernel state	416	Destroys the default loop again (frees all memory and kernel state
376	etc.). None of the active event watchers will be stopped in the normal	417	etc.). None of the active event watchers will be stopped in the normal
377	sense, so e.g. C<ev_is_active> might still return true. It is your	418	sense, so e.g. C<ev_is_active> might still return true. It is your
378	responsibility to either stop all watchers cleanly yoursef I<before>	419	responsibility to either stop all watchers cleanly yoursef I<before>
379	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
380	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
381	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>).
382		432
383	=item ev_loop_destroy (loop)	433	=item ev_loop_destroy (loop)
384		434
385	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
386	earlier call to C<ev_loop_new>.	436	earlier call to C<ev_loop_new>.
…		…
410		460
411	Like C<ev_default_fork>, but acts on an event loop created by	461	Like C<ev_default_fork>, but acts on an event loop created by
412	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	462	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
413	after fork, and how you do this is entirely your own problem.	463	after fork, and how you do this is entirely your own problem.
414		464
		465	=item unsigned int ev_loop_count (loop)
		466
		467	Returns the count of loop iterations for the loop, which is identical to
		468	the number of times libev did poll for new events. It starts at C<0> and
		469	happily wraps around with enough iterations.
		470
		471	This value can sometimes be useful as a generation counter of sorts (it
		472	"ticks" the number of loop iterations), as it roughly corresponds with
		473	C<ev_prepare> and C<ev_check> calls.
		474
415	=item unsigned int ev_backend (loop)	475	=item unsigned int ev_backend (loop)
416		476
417	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	477	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
418	use.	478	use.
419		479
…		…
421		481
422	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
423	received events and started processing them. This timestamp does not	483	received events and started processing them. This timestamp does not
424	change as long as callbacks are being processed, and this is also the base	484	change as long as callbacks are being processed, and this is also the base
425	time used for relative timers. You can treat it as the timestamp of the	485	time used for relative timers. You can treat it as the timestamp of the
426	event occuring (or more correctly, libev finding out about it).	486	event occurring (or more correctly, libev finding out about it).
427		487
428	=item ev_loop (loop, int flags)	488	=item ev_loop (loop, int flags)
429		489
430	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
431	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
…		…
452	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
453	usually a better approach for this kind of thing.	513	usually a better approach for this kind of thing.
454		514
455	Here are the gory details of what C<ev_loop> does:	515	Here are the gory details of what C<ev_loop> does:
456		516
		517	- Before the first iteration, call any pending watchers.
457	* If there are no active watchers (reference count is zero), return.	518	* If there are no active watchers (reference count is zero), return.
458	- Queue prepare watchers and then call all outstanding watchers.	519	- Queue all prepare watchers and then call all outstanding watchers.
459	- If we have been forked, recreate the kernel state.	520	- If we have been forked, recreate the kernel state.
460	- Update the kernel state with all outstanding changes.	521	- Update the kernel state with all outstanding changes.
461	- Update the "event loop time".	522	- Update the "event loop time".
462	- Calculate for how long to block.	523	- Calculate for how long to block.
463	- Block the process, waiting for any events.	524	- Block the process, waiting for any events.
…		…
514	Example: For some weird reason, unregister the above signal handler again.	575	Example: For some weird reason, unregister the above signal handler again.
515		576
516	ev_ref (loop);	577	ev_ref (loop);
517	ev_signal_stop (loop, &exitsig);	578	ev_signal_stop (loop, &exitsig);
518		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.
		602
		603	Likewise, by setting a higher I<timeout collect interval> you allow libev
		604	to spend more time collecting timeouts, at the expense of increased
		605	latency (the watcher callback will be called later). C<ev_io> watchers
		606	will not be affected.
		607
		608	Many (busy) programs can usually benefit by setting the io collect
		609	interval to a value near C<0.1> or so, which is often enough for
		610	interactive servers (of course not for games), likewise for timeouts. It
		611	usually doesn't make much sense to set it to a lower value than C<0.01>,
		612	as this approsaches the timing granularity of most systems.
		613
519	=back	614	=back
520		615
521		616
522	=head1 ANATOMY OF A WATCHER	617	=head1 ANATOMY OF A WATCHER
523		618
…		…
702	=item bool ev_is_pending (ev_TYPE *watcher)	797	=item bool ev_is_pending (ev_TYPE *watcher)
703		798
704	Returns a true value iff the watcher is pending, (i.e. it has outstanding	799	Returns a true value iff the watcher is pending, (i.e. it has outstanding
705	events but its callback has not yet been invoked). As long as a watcher	800	events but its callback has not yet been invoked). As long as a watcher
706	is pending (but not active) you must not call an init function on it (but	801	is pending (but not active) you must not call an init function on it (but
707	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	802	C<ev_TYPE_set> is safe), you must not change its priority, and you must
708	libev (e.g. you cnanot C<free ()> it).	803	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		804	it).
709		805
710	=item callback ev_cb (ev_TYPE *watcher)	806	=item callback ev_cb (ev_TYPE *watcher)
711		807
712	Returns the callback currently set on the watcher.	808	Returns the callback currently set on the watcher.
713		809
714	=item ev_cb_set (ev_TYPE *watcher, callback)	810	=item ev_cb_set (ev_TYPE *watcher, callback)
715		811
716	Change the callback. You can change the callback at virtually any time	812	Change the callback. You can change the callback at virtually any time
717	(modulo threads).	813	(modulo threads).
		814
		815	=item ev_set_priority (ev_TYPE *watcher, priority)
		816
		817	=item int ev_priority (ev_TYPE *watcher)
		818
		819	Set and query the priority of the watcher. The priority is a small
		820	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		821	(default: C<-2>). Pending watchers with higher priority will be invoked
		822	before watchers with lower priority, but priority will not keep watchers
		823	from being executed (except for C<ev_idle> watchers).
		824
		825	This means that priorities are I<only> used for ordering callback
		826	invocation after new events have been received. This is useful, for
		827	example, to reduce latency after idling, or more often, to bind two
		828	watchers on the same event and make sure one is called first.
		829
		830	If you need to suppress invocation when higher priority events are pending
		831	you need to look at C<ev_idle> watchers, which provide this functionality.
		832
		833	You I<must not> change the priority of a watcher as long as it is active or
		834	pending.
		835
		836	The default priority used by watchers when no priority has been set is
		837	always C<0>, which is supposed to not be too high and not be too low :).
		838
		839	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		840	fine, as long as you do not mind that the priority value you query might
		841	or might not have been adjusted to be within valid range.
		842
		843	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		844
		845	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		846	C<loop> nor C<revents> need to be valid as long as the watcher callback
		847	can deal with that fact.
		848
		849	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		850
		851	If the watcher is pending, this function returns clears its pending status
		852	and returns its C<revents> bitset (as if its callback was invoked). If the
		853	watcher isn't pending it does nothing and returns C<0>.
718		854
719	=back	855	=back
720		856
721		857
722	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	858	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
828	it is best to always use non-blocking I/O: An extra C<read>(2) returning	964	it is best to always use non-blocking I/O: An extra C<read>(2) returning
829	C<EAGAIN> is far preferable to a program hanging until some data arrives.	965	C<EAGAIN> is far preferable to a program hanging until some data arrives.
830		966
831	If you cannot run the fd in non-blocking mode (for example you should not	967	If you cannot run the fd in non-blocking mode (for example you should not
832	play around with an Xlib connection), then you have to seperately re-test	968	play around with an Xlib connection), then you have to seperately re-test
833	wether a file descriptor is really ready with a known-to-be good interface	969	whether a file descriptor is really ready with a known-to-be good interface
834	such as poll (fortunately in our Xlib example, Xlib already does this on	970	such as poll (fortunately in our Xlib example, Xlib already does this on
835	its own, so its quite safe to use).	971	its own, so its quite safe to use).
		972
		973	=head3 The special problem of disappearing file descriptors
		974
		975	Some backends (e.g. kqueue, epoll) need to be told about closing a file
		976	descriptor (either by calling C<close> explicitly or by any other means,
		977	such as C<dup>). The reason is that you register interest in some file
		978	descriptor, but when it goes away, the operating system will silently drop
		979	this interest. If another file descriptor with the same number then is
		980	registered with libev, there is no efficient way to see that this is, in
		981	fact, a different file descriptor.
		982
		983	To avoid having to explicitly tell libev about such cases, libev follows
		984	the following policy: Each time C<ev_io_set> is being called, libev
		985	will assume that this is potentially a new file descriptor, otherwise
		986	it is assumed that the file descriptor stays the same. That means that
		987	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		988	descriptor even if the file descriptor number itself did not change.
		989
		990	This is how one would do it normally anyway, the important point is that
		991	the libev application should not optimise around libev but should leave
		992	optimisations to libev.
		993
		994	=head3 The special problem of dup'ed file descriptors
		995
		996	Some backends (e.g. epoll), cannot register events for file descriptors,
		997	but only events for the underlying file descriptions. That menas when you
		998	have C<dup ()>'ed file descriptors and register events for them, only one
		999	file descriptor might actually receive events.
		1000
		1001	There is no workaorund possible except not registering events
		1002	for potentially C<dup ()>'ed file descriptors or to resort to
		1003	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
		1004
		1005	=head3 The special problem of fork
		1006
		1007	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
		1008	useless behaviour. Libev fully supports fork, but needs to be told about
		1009	it in the child.
		1010
		1011	To support fork in your programs, you either have to call
		1012	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
		1013	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
		1014	C<EVBACKEND_POLL>.
		1015
		1016
		1017	=head3 Watcher-Specific Functions
836		1018
837	=over 4	1019	=over 4
838		1020
839	=item ev_io_init (ev_io *, callback, int fd, int events)	1021	=item ev_io_init (ev_io *, callback, int fd, int events)
840		1022
…		…
893	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1075	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
894		1076
895	The callback is guarenteed to be invoked only when its timeout has passed,	1077	The callback is guarenteed to be invoked only when its timeout has passed,
896	but if multiple timers become ready during the same loop iteration then	1078	but if multiple timers become ready during the same loop iteration then
897	order of execution is undefined.	1079	order of execution is undefined.
		1080
		1081	=head3 Watcher-Specific Functions and Data Members
898		1082
899	=over 4	1083	=over 4
900		1084
901	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1085	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
902		1086
…		…
998	but on wallclock time (absolute time). You can tell a periodic watcher	1182	but on wallclock time (absolute time). You can tell a periodic watcher
999	to trigger "at" some specific point in time. For example, if you tell a	1183	to trigger "at" some specific point in time. For example, if you tell a
1000	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1184	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
1001	+ 10.>) and then reset your system clock to the last year, then it will	1185	+ 10.>) and then reset your system clock to the last year, then it will
1002	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1186	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
1003	roughly 10 seconds later and of course not if you reset your system time	1187	roughly 10 seconds later).
1004	again).
1005		1188
1006	They can also be used to implement vastly more complex timers, such as	1189	They can also be used to implement vastly more complex timers, such as
1007	triggering an event on eahc midnight, local time.	1190	triggering an event on each midnight, local time or other, complicated,
		1191	rules.
1008		1192
1009	As with timers, the callback is guarenteed to be invoked only when the	1193	As with timers, the callback is guarenteed to be invoked only when the
1010	time (C<at>) has been passed, but if multiple periodic timers become ready	1194	time (C<at>) has been passed, but if multiple periodic timers become ready
1011	during the same loop iteration then order of execution is undefined.	1195	during the same loop iteration then order of execution is undefined.
1012		1196
		1197	=head3 Watcher-Specific Functions and Data Members
		1198
1013	=over 4	1199	=over 4
1014		1200
1015	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1201	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
1016		1202
1017	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1203	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
1019	Lots of arguments, lets sort it out... There are basically three modes of	1205	Lots of arguments, lets sort it out... There are basically three modes of
1020	operation, and we will explain them from simplest to complex:	1206	operation, and we will explain them from simplest to complex:
1021		1207
1022	=over 4	1208	=over 4
1023		1209
1024	=item * absolute timer (interval = reschedule_cb = 0)	1210	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1025		1211
1026	In this configuration the watcher triggers an event at the wallclock time	1212	In this configuration the watcher triggers an event at the wallclock time
1027	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1213	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
1028	that is, if it is to be run at January 1st 2011 then it will run when the	1214	that is, if it is to be run at January 1st 2011 then it will run when the
1029	system time reaches or surpasses this time.	1215	system time reaches or surpasses this time.
1030		1216
1031	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1217	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1032		1218
1033	In this mode the watcher will always be scheduled to time out at the next	1219	In this mode the watcher will always be scheduled to time out at the next
1034	C<at + N * interval> time (for some integer N) and then repeat, regardless	1220	C<at + N * interval> time (for some integer N, which can also be negative)
1035	of any time jumps.	1221	and then repeat, regardless of any time jumps.
1036		1222
1037	This can be used to create timers that do not drift with respect to system	1223	This can be used to create timers that do not drift with respect to system
1038	time:	1224	time:
1039		1225
1040	ev_periodic_set (&periodic, 0., 3600., 0);	1226	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1046		1232
1047	Another way to think about it (for the mathematically inclined) is that	1233	Another way to think about it (for the mathematically inclined) is that
1048	C<ev_periodic> will try to run the callback in this mode at the next possible	1234	C<ev_periodic> will try to run the callback in this mode at the next possible
1049	time where C<time = at (mod interval)>, regardless of any time jumps.	1235	time where C<time = at (mod interval)>, regardless of any time jumps.
1050		1236
		1237	For numerical stability it is preferable that the C<at> value is near
		1238	C<ev_now ()> (the current time), but there is no range requirement for
		1239	this value.
		1240
1051	=item * manual reschedule mode (reschedule_cb = callback)	1241	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1052		1242
1053	In this mode the values for C<interval> and C<at> are both being	1243	In this mode the values for C<interval> and C<at> are both being
1054	ignored. Instead, each time the periodic watcher gets scheduled, the	1244	ignored. Instead, each time the periodic watcher gets scheduled, the
1055	reschedule callback will be called with the watcher as first, and the	1245	reschedule callback will be called with the watcher as first, and the
1056	current time as second argument.	1246	current time as second argument.
1057		1247
1058	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1248	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1059	ever, or make any event loop modifications>. If you need to stop it,	1249	ever, or make any event loop modifications>. If you need to stop it,
1060	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1250	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1061	starting a prepare watcher).	1251	starting an C<ev_prepare> watcher, which is legal).
1062		1252
1063	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	1253	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
1064	ev_tstamp now)>, e.g.:	1254	ev_tstamp now)>, e.g.:
1065		1255
1066	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1256	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
1089	Simply stops and restarts the periodic watcher again. This is only useful	1279	Simply stops and restarts the periodic watcher again. This is only useful
1090	when you changed some parameters or the reschedule callback would return	1280	when you changed some parameters or the reschedule callback would return
1091	a different time than the last time it was called (e.g. in a crond like	1281	a different time than the last time it was called (e.g. in a crond like
1092	program when the crontabs have changed).	1282	program when the crontabs have changed).
1093		1283
		1284	=item ev_tstamp offset [read-write]
		1285
		1286	When repeating, this contains the offset value, otherwise this is the
		1287	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1288
		1289	Can be modified any time, but changes only take effect when the periodic
		1290	timer fires or C<ev_periodic_again> is being called.
		1291
1094	=item ev_tstamp interval [read-write]	1292	=item ev_tstamp interval [read-write]
1095		1293
1096	The current interval value. Can be modified any time, but changes only	1294	The current interval value. Can be modified any time, but changes only
1097	take effect when the periodic timer fires or C<ev_periodic_again> is being	1295	take effect when the periodic timer fires or C<ev_periodic_again> is being
1098	called.	1296	called.
…		…
1100	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]	1298	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
1101		1299
1102	The current reschedule callback, or C<0>, if this functionality is	1300	The current reschedule callback, or C<0>, if this functionality is
1103	switched off. Can be changed any time, but changes only take effect when	1301	switched off. Can be changed any time, but changes only take effect when
1104	the periodic timer fires or C<ev_periodic_again> is being called.	1302	the periodic timer fires or C<ev_periodic_again> is being called.
		1303
		1304	=item ev_tstamp at [read-only]
		1305
		1306	When active, contains the absolute time that the watcher is supposed to
		1307	trigger next.
1105		1308
1106	=back	1309	=back
1107		1310
1108	Example: Call a callback every hour, or, more precisely, whenever the	1311	Example: Call a callback every hour, or, more precisely, whenever the
1109	system clock is divisible by 3600. The callback invocation times have	1312	system clock is divisible by 3600. The callback invocation times have
…		…
1151	with the kernel (thus it coexists with your own signal handlers as long	1354	with the kernel (thus it coexists with your own signal handlers as long
1152	as you don't register any with libev). Similarly, when the last signal	1355	as you don't register any with libev). Similarly, when the last signal
1153	watcher for a signal is stopped libev will reset the signal handler to	1356	watcher for a signal is stopped libev will reset the signal handler to
1154	SIG_DFL (regardless of what it was set to before).	1357	SIG_DFL (regardless of what it was set to before).
1155		1358
		1359	=head3 Watcher-Specific Functions and Data Members
		1360
1156	=over 4	1361	=over 4
1157		1362
1158	=item ev_signal_init (ev_signal *, callback, int signum)	1363	=item ev_signal_init (ev_signal *, callback, int signum)
1159		1364
1160	=item ev_signal_set (ev_signal *, int signum)	1365	=item ev_signal_set (ev_signal *, int signum)
…		…
1171		1376
1172	=head2 C<ev_child> - watch out for process status changes	1377	=head2 C<ev_child> - watch out for process status changes
1173		1378
1174	Child watchers trigger when your process receives a SIGCHLD in response to	1379	Child watchers trigger when your process receives a SIGCHLD in response to
1175	some child status changes (most typically when a child of yours dies).	1380	some child status changes (most typically when a child of yours dies).
		1381
		1382	=head3 Watcher-Specific Functions and Data Members
1176		1383
1177	=over 4	1384	=over 4
1178		1385
1179	=item ev_child_init (ev_child *, callback, int pid)	1386	=item ev_child_init (ev_child *, callback, int pid)
1180		1387
…		…
1248	reader). Inotify will be used to give hints only and should not change the	1455	reader). Inotify will be used to give hints only and should not change the
1249	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1456	semantics of C<ev_stat> watchers, which means that libev sometimes needs
1250	to fall back to regular polling again even with inotify, but changes are	1457	to fall back to regular polling again even with inotify, but changes are
1251	usually detected immediately, and if the file exists there will be no	1458	usually detected immediately, and if the file exists there will be no
1252	polling.	1459	polling.
		1460
		1461	=head3 Watcher-Specific Functions and Data Members
1253		1462
1254	=over 4	1463	=over 4
1255		1464
1256	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1465	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1257		1466
…		…
1321	ev_stat_start (loop, &passwd);	1530	ev_stat_start (loop, &passwd);
1322		1531
1323		1532
1324	=head2 C<ev_idle> - when you've got nothing better to do...	1533	=head2 C<ev_idle> - when you've got nothing better to do...
1325		1534
1326	Idle watchers trigger events when there are no other events are pending	1535	Idle watchers trigger events when no other events of the same or higher
1327	(prepare, check and other idle watchers do not count). That is, as long	1536	priority are pending (prepare, check and other idle watchers do not
1328	as your process is busy handling sockets or timeouts (or even signals,	1537	count).
1329	imagine) it will not be triggered. But when your process is idle all idle	1538
1330	watchers are being called again and again, once per event loop iteration -	1539	That is, as long as your process is busy handling sockets or timeouts
		1540	(or even signals, imagine) of the same or higher priority it will not be
		1541	triggered. But when your process is idle (or only lower-priority watchers
		1542	are pending), the idle watchers are being called once per event loop
1331	until stopped, that is, or your process receives more events and becomes	1543	iteration - until stopped, that is, or your process receives more events
1332	busy.	1544	and becomes busy again with higher priority stuff.
1333		1545
1334	The most noteworthy effect is that as long as any idle watchers are	1546	The most noteworthy effect is that as long as any idle watchers are
1335	active, the process will not block when waiting for new events.	1547	active, the process will not block when waiting for new events.
1336		1548
1337	Apart from keeping your process non-blocking (which is a useful	1549	Apart from keeping your process non-blocking (which is a useful
1338	effect on its own sometimes), idle watchers are a good place to do	1550	effect on its own sometimes), idle watchers are a good place to do
1339	"pseudo-background processing", or delay processing stuff to after the	1551	"pseudo-background processing", or delay processing stuff to after the
1340	event loop has handled all outstanding events.	1552	event loop has handled all outstanding events.
		1553
		1554	=head3 Watcher-Specific Functions and Data Members
1341		1555
1342	=over 4	1556	=over 4
1343		1557
1344	=item ev_idle_init (ev_signal *, callback)	1558	=item ev_idle_init (ev_signal *, callback)
1345		1559
…		…
1403	with priority higher than or equal to the event loop and one coroutine	1617	with priority higher than or equal to the event loop and one coroutine
1404	of lower priority, but only once, using idle watchers to keep the event	1618	of lower priority, but only once, using idle watchers to keep the event
1405	loop from blocking if lower-priority coroutines are active, thus mapping	1619	loop from blocking if lower-priority coroutines are active, thus mapping
1406	low-priority coroutines to idle/background tasks).	1620	low-priority coroutines to idle/background tasks).
1407		1621
		1622	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1623	priority, to ensure that they are being run before any other watchers
		1624	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1625	too) should not activate ("feed") events into libev. While libev fully
		1626	supports this, they will be called before other C<ev_check> watchers did
		1627	their job. As C<ev_check> watchers are often used to embed other event
		1628	loops those other event loops might be in an unusable state until their
		1629	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
		1630	others).
		1631
		1632	=head3 Watcher-Specific Functions and Data Members
		1633
1408	=over 4	1634	=over 4
1409		1635
1410	=item ev_prepare_init (ev_prepare *, callback)	1636	=item ev_prepare_init (ev_prepare *, callback)
1411		1637
1412	=item ev_check_init (ev_check *, callback)	1638	=item ev_check_init (ev_check *, callback)
…		…
1415	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1641	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1416	macros, but using them is utterly, utterly and completely pointless.	1642	macros, but using them is utterly, utterly and completely pointless.
1417		1643
1418	=back	1644	=back
1419		1645
1420	Example: To include a library such as adns, you would add IO watchers	1646	There are a number of principal ways to embed other event loops or modules
1421	and a timeout watcher in a prepare handler, as required by libadns, and	1647	into libev. Here are some ideas on how to include libadns into libev
		1648	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1649	use for an actually working example. Another Perl module named C<EV::Glib>
		1650	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1651	into the Glib event loop).
		1652
		1653	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1422	in a check watcher, destroy them and call into libadns. What follows is	1654	and in a check watcher, destroy them and call into libadns. What follows
1423	pseudo-code only of course:	1655	is pseudo-code only of course. This requires you to either use a low
		1656	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1657	the callbacks for the IO/timeout watchers might not have been called yet.
1424		1658
1425	static ev_io iow [nfd];	1659	static ev_io iow [nfd];
1426	static ev_timer tw;	1660	static ev_timer tw;
1427		1661
1428	static void	1662	static void
1429	io_cb (ev_loop loop, ev_io w, int revents)	1663	io_cb (ev_loop loop, ev_io w, int revents)
1430	{	1664	{
1431	// set the relevant poll flags
1432	// could also call adns_processreadable etc. here
1433	struct pollfd fd = (struct pollfd )w->data;
1434	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1435	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1436	}	1665	}
1437		1666
1438	// create io watchers for each fd and a timer before blocking	1667	// create io watchers for each fd and a timer before blocking
1439	static void	1668	static void
1440	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1669	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1441	{	1670	{
1442	int timeout = 3600000;truct pollfd fds [nfd];	1671	int timeout = 3600000;
		1672	struct pollfd fds [nfd];
1443	// actual code will need to loop here and realloc etc.	1673	// actual code will need to loop here and realloc etc.
1444	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1674	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1445		1675
1446	/* the callback is illegal, but won't be called as we stop during check */	1676	/* the callback is illegal, but won't be called as we stop during check */
1447	ev_timer_init (&tw, 0, timeout * 1e-3);	1677	ev_timer_init (&tw, 0, timeout * 1e-3);
1448	ev_timer_start (loop, &tw);	1678	ev_timer_start (loop, &tw);
1449		1679
1450	// create on ev_io per pollfd	1680	// create one ev_io per pollfd
1451	for (int i = 0; i < nfd; ++i)	1681	for (int i = 0; i < nfd; ++i)
1452	{	1682	{
1453	ev_io_init (iow + i, io_cb, fds [i].fd,	1683	ev_io_init (iow + i, io_cb, fds [i].fd,
1454	((fds [i].events & POLLIN ? EV_READ : 0)	1684	((fds [i].events & POLLIN ? EV_READ : 0)
1455	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1685	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1456		1686
1457	fds [i].revents = 0;	1687	fds [i].revents = 0;
1458	iow [i].data = fds + i;
1459	ev_io_start (loop, iow + i);	1688	ev_io_start (loop, iow + i);
1460	}	1689	}
1461	}	1690	}
1462		1691
1463	// stop all watchers after blocking	1692	// stop all watchers after blocking
…		…
1465	adns_check_cb (ev_loop loop, ev_check w, int revents)	1694	adns_check_cb (ev_loop loop, ev_check w, int revents)
1466	{	1695	{
1467	ev_timer_stop (loop, &tw);	1696	ev_timer_stop (loop, &tw);
1468		1697
1469	for (int i = 0; i < nfd; ++i)	1698	for (int i = 0; i < nfd; ++i)
		1699	{
		1700	// set the relevant poll flags
		1701	// could also call adns_processreadable etc. here
		1702	struct pollfd *fd = fds + i;
		1703	int revents = ev_clear_pending (iow + i);
		1704	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1705	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1706
		1707	// now stop the watcher
1470	ev_io_stop (loop, iow + i);	1708	ev_io_stop (loop, iow + i);
		1709	}
1471		1710
1472	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1711	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1712	}
		1713
		1714	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1715	in the prepare watcher and would dispose of the check watcher.
		1716
		1717	Method 3: If the module to be embedded supports explicit event
		1718	notification (adns does), you can also make use of the actual watcher
		1719	callbacks, and only destroy/create the watchers in the prepare watcher.
		1720
		1721	static void
		1722	timer_cb (EV_P_ ev_timer *w, int revents)
		1723	{
		1724	adns_state ads = (adns_state)w->data;
		1725	update_now (EV_A);
		1726
		1727	adns_processtimeouts (ads, &tv_now);
		1728	}
		1729
		1730	static void
		1731	io_cb (EV_P_ ev_io *w, int revents)
		1732	{
		1733	adns_state ads = (adns_state)w->data;
		1734	update_now (EV_A);
		1735
		1736	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1737	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1738	}
		1739
		1740	// do not ever call adns_afterpoll
		1741
		1742	Method 4: Do not use a prepare or check watcher because the module you
		1743	want to embed is too inflexible to support it. Instead, youc na override
		1744	their poll function. The drawback with this solution is that the main
		1745	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1746	this.
		1747
		1748	static gint
		1749	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1750	{
		1751	int got_events = 0;
		1752
		1753	for (n = 0; n < nfds; ++n)
		1754	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1755
		1756	if (timeout >= 0)
		1757	// create/start timer
		1758
		1759	// poll
		1760	ev_loop (EV_A_ 0);
		1761
		1762	// stop timer again
		1763	if (timeout >= 0)
		1764	ev_timer_stop (EV_A_ &to);
		1765
		1766	// stop io watchers again - their callbacks should have set
		1767	for (n = 0; n < nfds; ++n)
		1768	ev_io_stop (EV_A_ iow [n]);
		1769
		1770	return got_events;
1473	}	1771	}
1474		1772
1475		1773
1476	=head2 C<ev_embed> - when one backend isn't enough...	1774	=head2 C<ev_embed> - when one backend isn't enough...
1477		1775
1478	This is a rather advanced watcher type that lets you embed one event loop	1776	This is a rather advanced watcher type that lets you embed one event loop
1479	into another (currently only C<ev_io> events are supported in the embedded	1777	into another (currently only C<ev_io> events are supported in the embedded
1480	loop, other types of watchers might be handled in a delayed or incorrect	1778	loop, other types of watchers might be handled in a delayed or incorrect
1481	fashion and must not be used).	1779	fashion and must not be used). (See portability notes, below).
1482		1780
1483	There are primarily two reasons you would want that: work around bugs and	1781	There are primarily two reasons you would want that: work around bugs and
1484	prioritise I/O.	1782	prioritise I/O.
1485		1783
1486	As an example for a bug workaround, the kqueue backend might only support	1784	As an example for a bug workaround, the kqueue backend might only support
…		…
1541	ev_embed_start (loop_hi, &embed);	1839	ev_embed_start (loop_hi, &embed);
1542	}	1840	}
1543	else	1841	else
1544	loop_lo = loop_hi;	1842	loop_lo = loop_hi;
1545		1843
		1844	=head2 Portability notes
		1845
		1846	Kqueue is nominally embeddable, but this is broken on all BSDs that I
		1847	tried, in various ways. Usually the embedded event loop will simply never
		1848	receive events, sometimes it will only trigger a few times, sometimes in a
		1849	loop. Epoll is also nominally embeddable, but many Linux kernel versions
		1850	will always eport the epoll fd as ready, even when no events are pending.
		1851
		1852	While libev allows embedding these backends (they are contained in
		1853	C<ev_embeddable_backends ()>), take extreme care that it will actually
		1854	work.
		1855
		1856	When in doubt, create a dynamic event loop forced to use sockets (this
		1857	usually works) and possibly another thread and a pipe or so to report to
		1858	your main event loop.
		1859
		1860	=head3 Watcher-Specific Functions and Data Members
		1861
1546	=over 4	1862	=over 4
1547		1863
1548	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)	1864	=item ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)
1549		1865
1550	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)	1866	=item ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)
…		…
1559		1875
1560	Make a single, non-blocking sweep over the embedded loop. This works	1876	Make a single, non-blocking sweep over the embedded loop. This works
1561	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1877	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1562	apropriate way for embedded loops.	1878	apropriate way for embedded loops.
1563		1879
1564	=item struct ev_loop *loop [read-only]	1880	=item struct ev_loop *other [read-only]
1565		1881
1566	The embedded event loop.	1882	The embedded event loop.
1567		1883
1568	=back	1884	=back
1569		1885
…		…
1576	event loop blocks next and before C<ev_check> watchers are being called,	1892	event loop blocks next and before C<ev_check> watchers are being called,
1577	and only in the child after the fork. If whoever good citizen calling	1893	and only in the child after the fork. If whoever good citizen calling
1578	C<ev_default_fork> cheats and calls it in the wrong process, the fork	1894	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1579	handlers will be invoked, too, of course.	1895	handlers will be invoked, too, of course.
1580		1896
		1897	=head3 Watcher-Specific Functions and Data Members
		1898
1581	=over 4	1899	=over 4
1582		1900
1583	=item ev_fork_init (ev_signal *, callback)	1901	=item ev_fork_init (ev_signal *, callback)
1584		1902
1585	Initialises and configures the fork watcher - it has no parameters of any	1903	Initialises and configures the fork watcher - it has no parameters of any
…		…
1681		1999
1682	To use it,	2000	To use it,
1683		2001
1684	#include <ev++.h>	2002	#include <ev++.h>
1685		2003
1686	(it is not installed by default). This automatically includes F<ev.h>	2004	This automatically includes F<ev.h> and puts all of its definitions (many
1687	and puts all of its definitions (many of them macros) into the global	2005	of them macros) into the global namespace. All C++ specific things are
1688	namespace. All C++ specific things are put into the C<ev> namespace.	2006	put into the C<ev> namespace. It should support all the same embedding
		2007	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1689		2008
1690	It should support all the same embedding options as F<ev.h>, most notably	2009	Care has been taken to keep the overhead low. The only data member the C++
1691	C<EV_MULTIPLICITY>.	2010	classes add (compared to plain C-style watchers) is the event loop pointer
		2011	that the watcher is associated with (or no additional members at all if
		2012	you disable C<EV_MULTIPLICITY> when embedding libev).
		2013
		2014	Currently, functions, and static and non-static member functions can be
		2015	used as callbacks. Other types should be easy to add as long as they only
		2016	need one additional pointer for context. If you need support for other
		2017	types of functors please contact the author (preferably after implementing
		2018	it).
1692		2019
1693	Here is a list of things available in the C<ev> namespace:	2020	Here is a list of things available in the C<ev> namespace:
1694		2021
1695	=over 4	2022	=over 4
1696		2023
…		…
1712		2039
1713	All of those classes have these methods:	2040	All of those classes have these methods:
1714		2041
1715	=over 4	2042	=over 4
1716		2043
1717	=item ev::TYPE::TYPE (object , object::method )	2044	=item ev::TYPE::TYPE ()
1718		2045
1719	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	2046	=item ev::TYPE::TYPE (struct ev_loop *)
1720		2047
1721	=item ev::TYPE::~TYPE	2048	=item ev::TYPE::~TYPE
1722		2049
1723	The constructor takes a pointer to an object and a method pointer to	2050	The constructor (optionally) takes an event loop to associate the watcher
1724	the event handler callback to call in this class. The constructor calls	2051	with. If it is omitted, it will use C<EV_DEFAULT>.
1725	C<ev_init> for you, which means you have to call the C<set> method	2052
1726	before starting it. If you do not specify a loop then the constructor	2053	The constructor calls C<ev_init> for you, which means you have to call the
1727	automatically associates the default loop with this watcher.	2054	C<set> method before starting it.
		2055
		2056	It will not set a callback, however: You have to call the templated C<set>
		2057	method to set a callback before you can start the watcher.
		2058
		2059	(The reason why you have to use a method is a limitation in C++ which does
		2060	not allow explicit template arguments for constructors).
1728		2061
1729	The destructor automatically stops the watcher if it is active.	2062	The destructor automatically stops the watcher if it is active.
		2063
		2064	=item w->set<class, &class::method> (object *)
		2065
		2066	This method sets the callback method to call. The method has to have a
		2067	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		2068	first argument and the C<revents> as second. The object must be given as
		2069	parameter and is stored in the C<data> member of the watcher.
		2070
		2071	This method synthesizes efficient thunking code to call your method from
		2072	the C callback that libev requires. If your compiler can inline your
		2073	callback (i.e. it is visible to it at the place of the C<set> call and
		2074	your compiler is good :), then the method will be fully inlined into the
		2075	thunking function, making it as fast as a direct C callback.
		2076
		2077	Example: simple class declaration and watcher initialisation
		2078
		2079	struct myclass
		2080	{
		2081	void io_cb (ev::io &w, int revents) { }
		2082	}
		2083
		2084	myclass obj;
		2085	ev::io iow;
		2086	iow.set <myclass, &myclass::io_cb> (&obj);
		2087
		2088	=item w->set<function> (void *data = 0)
		2089
		2090	Also sets a callback, but uses a static method or plain function as
		2091	callback. The optional C<data> argument will be stored in the watcher's
		2092	C<data> member and is free for you to use.
		2093
		2094	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2095
		2096	See the method-C<set> above for more details.
		2097
		2098	Example:
		2099
		2100	static void io_cb (ev::io &w, int revents) { }
		2101	iow.set <io_cb> ();
1730		2102
1731	=item w->set (struct ev_loop *)	2103	=item w->set (struct ev_loop *)
1732		2104
1733	Associates a different C<struct ev_loop> with this watcher. You can only	2105	Associates a different C<struct ev_loop> with this watcher. You can only
1734	do this when the watcher is inactive (and not pending either).	2106	do this when the watcher is inactive (and not pending either).
1735		2107
1736	=item w->set ([args])	2108	=item w->set ([args])
1737		2109
1738	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2110	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1739	called at least once. Unlike the C counterpart, an active watcher gets	2111	called at least once. Unlike the C counterpart, an active watcher gets
1740	automatically stopped and restarted.	2112	automatically stopped and restarted when reconfiguring it with this
		2113	method.
1741		2114
1742	=item w->start ()	2115	=item w->start ()
1743		2116
1744	Starts the watcher. Note that there is no C<loop> argument as the	2117	Starts the watcher. Note that there is no C<loop> argument, as the
1745	constructor already takes the loop.	2118	constructor already stores the event loop.
1746		2119
1747	=item w->stop ()	2120	=item w->stop ()
1748		2121
1749	Stops the watcher if it is active. Again, no C<loop> argument.	2122	Stops the watcher if it is active. Again, no C<loop> argument.
1750		2123
1751	=item w->again () C<ev::timer>, C<ev::periodic> only	2124	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1752		2125
1753	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2126	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1754	C<ev_TYPE_again> function.	2127	C<ev_TYPE_again> function.
1755		2128
1756	=item w->sweep () C<ev::embed> only	2129	=item w->sweep () (C<ev::embed> only)
1757		2130
1758	Invokes C<ev_embed_sweep>.	2131	Invokes C<ev_embed_sweep>.
1759		2132
1760	=item w->update () C<ev::stat> only	2133	=item w->update () (C<ev::stat> only)
1761		2134
1762	Invokes C<ev_stat_stat>.	2135	Invokes C<ev_stat_stat>.
1763		2136
1764	=back	2137	=back
1765		2138
…		…
1775		2148
1776	myclass ();	2149	myclass ();
1777	}	2150	}
1778		2151
1779	myclass::myclass (int fd)	2152	myclass::myclass (int fd)
1780	: io (this, &myclass::io_cb),
1781	idle (this, &myclass::idle_cb)
1782	{	2153	{
		2154	io .set <myclass, &myclass::io_cb > (this);
		2155	idle.set <myclass, &myclass::idle_cb> (this);
		2156
1783	io.start (fd, ev::READ);	2157	io.start (fd, ev::READ);
1784	}	2158	}
1785		2159
1786		2160
1787	=head1 MACRO MAGIC	2161	=head1 MACRO MAGIC
1788		2162
1789	Libev can be compiled with a variety of options, the most fundemantal is	2163	Libev can be compiled with a variety of options, the most fundamantal
1790	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2164	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1791	callbacks have an initial C<struct ev_loop *> argument.	2165	functions and callbacks have an initial C<struct ev_loop *> argument.
1792		2166
1793	To make it easier to write programs that cope with either variant, the	2167	To make it easier to write programs that cope with either variant, the
1794	following macros are defined:	2168	following macros are defined:
1795		2169
1796	=over 4	2170	=over 4
…		…
1828	Similar to the other two macros, this gives you the value of the default	2202	Similar to the other two macros, this gives you the value of the default
1829	loop, if multiple loops are supported ("ev loop default").	2203	loop, if multiple loops are supported ("ev loop default").
1830		2204
1831	=back	2205	=back
1832		2206
1833	Example: Declare and initialise a check watcher, working regardless of	2207	Example: Declare and initialise a check watcher, utilising the above
1834	wether multiple loops are supported or not.	2208	macros so it will work regardless of whether multiple loops are supported
		2209	or not.
1835		2210
1836	static void	2211	static void
1837	check_cb (EV_P_ ev_timer *w, int revents)	2212	check_cb (EV_P_ ev_timer *w, int revents)
1838	{	2213	{
1839	ev_check_stop (EV_A_ w);	2214	ev_check_stop (EV_A_ w);
…		…
1842	ev_check check;	2217	ev_check check;
1843	ev_check_init (&check, check_cb);	2218	ev_check_init (&check, check_cb);
1844	ev_check_start (EV_DEFAULT_ &check);	2219	ev_check_start (EV_DEFAULT_ &check);
1845	ev_loop (EV_DEFAULT_ 0);	2220	ev_loop (EV_DEFAULT_ 0);
1846		2221
1847
1848	=head1 EMBEDDING	2222	=head1 EMBEDDING
1849		2223
1850	Libev can (and often is) directly embedded into host	2224	Libev can (and often is) directly embedded into host
1851	applications. Examples of applications that embed it include the Deliantra	2225	applications. Examples of applications that embed it include the Deliantra
1852	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2226	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1853	and rxvt-unicode.	2227	and rxvt-unicode.
1854		2228
1855	The goal is to enable you to just copy the neecssary files into your	2229	The goal is to enable you to just copy the necessary files into your
1856	source directory without having to change even a single line in them, so	2230	source directory without having to change even a single line in them, so
1857	you can easily upgrade by simply copying (or having a checked-out copy of	2231	you can easily upgrade by simply copying (or having a checked-out copy of
1858	libev somewhere in your source tree).	2232	libev somewhere in your source tree).
1859		2233
1860	=head2 FILESETS	2234	=head2 FILESETS
…		…
1891	ev_vars.h	2265	ev_vars.h
1892	ev_wrap.h	2266	ev_wrap.h
1893		2267
1894	ev_win32.c required on win32 platforms only	2268	ev_win32.c required on win32 platforms only
1895		2269
1896	ev_select.c only when select backend is enabled (which is by default)	2270	ev_select.c only when select backend is enabled (which is enabled by default)
1897	ev_poll.c only when poll backend is enabled (disabled by default)	2271	ev_poll.c only when poll backend is enabled (disabled by default)
1898	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2272	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1899	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2273	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1900	ev_port.c only when the solaris port backend is enabled (disabled by default)	2274	ev_port.c only when the solaris port backend is enabled (disabled by default)
1901		2275
…		…
1950		2324
1951	If defined to be C<1>, libev will try to detect the availability of the	2325	If defined to be C<1>, libev will try to detect the availability of the
1952	monotonic clock option at both compiletime and runtime. Otherwise no use	2326	monotonic clock option at both compiletime and runtime. Otherwise no use
1953	of the monotonic clock option will be attempted. If you enable this, you	2327	of the monotonic clock option will be attempted. If you enable this, you
1954	usually have to link against librt or something similar. Enabling it when	2328	usually have to link against librt or something similar. Enabling it when
1955	the functionality isn't available is safe, though, althoguh you have	2329	the functionality isn't available is safe, though, although you have
1956	to make sure you link against any libraries where the C<clock_gettime>	2330	to make sure you link against any libraries where the C<clock_gettime>
1957	function is hiding in (often F<-lrt>).	2331	function is hiding in (often F<-lrt>).
1958		2332
1959	=item EV_USE_REALTIME	2333	=item EV_USE_REALTIME
1960		2334
1961	If defined to be C<1>, libev will try to detect the availability of the	2335	If defined to be C<1>, libev will try to detect the availability of the
1962	realtime clock option at compiletime (and assume its availability at	2336	realtime clock option at compiletime (and assume its availability at
1963	runtime if successful). Otherwise no use of the realtime clock option will	2337	runtime if successful). Otherwise no use of the realtime clock option will
1964	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2338	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
1965	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2339	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
1966	in the description of C<EV_USE_MONOTONIC>, though.	2340	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
		2341
		2342	=item EV_USE_NANOSLEEP
		2343
		2344	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
		2345	and will use it for delays. Otherwise it will use C<select ()>.
1967		2346
1968	=item EV_USE_SELECT	2347	=item EV_USE_SELECT
1969		2348
1970	If undefined or defined to be C<1>, libev will compile in support for the	2349	If undefined or defined to be C<1>, libev will compile in support for the
1971	C<select>(2) backend. No attempt at autodetection will be done: if no	2350	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
2064	will have the C<struct ev_loop *> as first argument, and you can create	2443	will have the C<struct ev_loop *> as first argument, and you can create
2065	additional independent event loops. Otherwise there will be no support	2444	additional independent event loops. Otherwise there will be no support
2066	for multiple event loops and there is no first event loop pointer	2445	for multiple event loops and there is no first event loop pointer
2067	argument. Instead, all functions act on the single default loop.	2446	argument. Instead, all functions act on the single default loop.
2068		2447
		2448	=item EV_MINPRI
		2449
		2450	=item EV_MAXPRI
		2451
		2452	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2453	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2454	provide for more priorities by overriding those symbols (usually defined
		2455	to be C<-2> and C<2>, respectively).
		2456
		2457	When doing priority-based operations, libev usually has to linearly search
		2458	all the priorities, so having many of them (hundreds) uses a lot of space
		2459	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2460	fine.
		2461
		2462	If your embedding app does not need any priorities, defining these both to
		2463	C<0> will save some memory and cpu.
		2464
2069	=item EV_PERIODIC_ENABLE	2465	=item EV_PERIODIC_ENABLE
2070		2466
2071	If undefined or defined to be C<1>, then periodic timers are supported. If	2467	If undefined or defined to be C<1>, then periodic timers are supported. If
		2468	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2469	code.
		2470
		2471	=item EV_IDLE_ENABLE
		2472
		2473	If undefined or defined to be C<1>, then idle watchers are supported. If
2072	defined to be C<0>, then they are not. Disabling them saves a few kB of	2474	defined to be C<0>, then they are not. Disabling them saves a few kB of
2073	code.	2475	code.
2074		2476
2075	=item EV_EMBED_ENABLE	2477	=item EV_EMBED_ENABLE
2076		2478
…		…
2127		2529
2128	=item ev_set_cb (ev, cb)	2530	=item ev_set_cb (ev, cb)
2129		2531
2130	Can be used to change the callback member declaration in each watcher,	2532	Can be used to change the callback member declaration in each watcher,
2131	and the way callbacks are invoked and set. Must expand to a struct member	2533	and the way callbacks are invoked and set. Must expand to a struct member
2132	definition and a statement, respectively. See the F<ev.v> header file for	2534	definition and a statement, respectively. See the F<ev.h> header file for
2133	their default definitions. One possible use for overriding these is to	2535	their default definitions. One possible use for overriding these is to
2134	avoid the C<struct ev_loop *> as first argument in all cases, or to use	2536	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2135	method calls instead of plain function calls in C++.	2537	method calls instead of plain function calls in C++.
		2538
		2539	=head2 EXPORTED API SYMBOLS
		2540
		2541	If you need to re-export the API (e.g. via a dll) and you need a list of
		2542	exported symbols, you can use the provided F<Symbol.*> files which list
		2543	all public symbols, one per line:
		2544
		2545	Symbols.ev for libev proper
		2546	Symbols.event for the libevent emulation
		2547
		2548	This can also be used to rename all public symbols to avoid clashes with
		2549	multiple versions of libev linked together (which is obviously bad in
		2550	itself, but sometimes it is inconvinient to avoid this).
		2551
		2552	A sed command like this will create wrapper C<#define>'s that you need to
		2553	include before including F<ev.h>:
		2554
		2555	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2556
		2557	This would create a file F<wrap.h> which essentially looks like this:
		2558
		2559	#define ev_backend myprefix_ev_backend
		2560	#define ev_check_start myprefix_ev_check_start
		2561	#define ev_check_stop myprefix_ev_check_stop
		2562	...
2136		2563
2137	=head2 EXAMPLES	2564	=head2 EXAMPLES
2138		2565
2139	For a real-world example of a program the includes libev	2566	For a real-world example of a program the includes libev
2140	verbatim, you can have a look at the EV perl module	2567	verbatim, you can have a look at the EV perl module
…		…
2143	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2570	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2144	will be compiled. It is pretty complex because it provides its own header	2571	will be compiled. It is pretty complex because it provides its own header
2145	file.	2572	file.
2146		2573
2147	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2574	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2148	that everybody includes and which overrides some autoconf choices:	2575	that everybody includes and which overrides some configure choices:
2149		2576
		2577	#define EV_MINIMAL 1
2150	#define EV_USE_POLL 0	2578	#define EV_USE_POLL 0
2151	#define EV_MULTIPLICITY 0	2579	#define EV_MULTIPLICITY 0
2152	#define EV_PERIODICS 0	2580	#define EV_PERIODIC_ENABLE 0
		2581	#define EV_STAT_ENABLE 0
		2582	#define EV_FORK_ENABLE 0
2153	#define EV_CONFIG_H <config.h>	2583	#define EV_CONFIG_H <config.h>
		2584	#define EV_MINPRI 0
		2585	#define EV_MAXPRI 0
2154		2586
2155	#include "ev++.h"	2587	#include "ev++.h"
2156		2588
2157	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2589	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2158		2590
…		…
2164		2596
2165	In this section the complexities of (many of) the algorithms used inside	2597	In this section the complexities of (many of) the algorithms used inside
2166	libev will be explained. For complexity discussions about backends see the	2598	libev will be explained. For complexity discussions about backends see the
2167	documentation for C<ev_default_init>.	2599	documentation for C<ev_default_init>.
2168		2600
		2601	All of the following are about amortised time: If an array needs to be
		2602	extended, libev needs to realloc and move the whole array, but this
		2603	happens asymptotically never with higher number of elements, so O(1) might
		2604	mean it might do a lengthy realloc operation in rare cases, but on average
		2605	it is much faster and asymptotically approaches constant time.
		2606
2169	=over 4	2607	=over 4
2170		2608
2171	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2609	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2172		2610
		2611	This means that, when you have a watcher that triggers in one hour and
		2612	there are 100 watchers that would trigger before that then inserting will
		2613	have to skip those 100 watchers.
		2614
2173	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2615	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2174		2616
		2617	That means that for changing a timer costs less than removing/adding them
		2618	as only the relative motion in the event queue has to be paid for.
		2619
2175	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2620	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2176		2621
		2622	These just add the watcher into an array or at the head of a list.
2177	=item Stopping check/prepare/idle watchers: O(1)	2623	=item Stopping check/prepare/idle watchers: O(1)
2178		2624
2179	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2625	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2180		2626
		2627	These watchers are stored in lists then need to be walked to find the
		2628	correct watcher to remove. The lists are usually short (you don't usually
		2629	have many watchers waiting for the same fd or signal).
		2630
2181	=item Finding the next timer per loop iteration: O(1)	2631	=item Finding the next timer per loop iteration: O(1)
2182		2632
2183	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2633	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2184		2634
		2635	A change means an I/O watcher gets started or stopped, which requires
		2636	libev to recalculate its status (and possibly tell the kernel).
		2637
2185	=item Activating one watcher: O(1)	2638	=item Activating one watcher: O(1)
2186		2639
		2640	=item Priority handling: O(number_of_priorities)
		2641
		2642	Priorities are implemented by allocating some space for each
		2643	priority. When doing priority-based operations, libev usually has to
		2644	linearly search all the priorities.
		2645
2187	=back	2646	=back
2188		2647
2189		2648
2190	=head1 AUTHOR	2649	=head1 AUTHOR
2191		2650

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Comparing libev/ev.pod (file contents): Revision 1.61 by root, Thu Nov 29 12:21:05 2007 UTC vs. Revision 1.98 by root, Sat Dec 22 06:10:25 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.61 by root, Thu Nov 29 12:21:05 2007 UTC vs.
Revision 1.98 by root, Sat Dec 22 06:10:25 2007 UTC