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

Comparing libev/ev.pod (file contents):
Revision 1.26 by root, Tue Nov 13 03:11:57 2007 UTC vs.
Revision 1.32 by root, Fri Nov 23 08:36:35 2007 UTC

…		…
75	Usually, it's a good idea to terminate if the major versions mismatch,	75	Usually, it's a good idea to terminate if the major versions mismatch,
76	as this indicates an incompatible change. Minor versions are usually	76	as this indicates an incompatible change. Minor versions are usually
77	compatible to older versions, so a larger minor version alone is usually	77	compatible to older versions, so a larger minor version alone is usually
78	not a problem.	78	not a problem.
79		79
		80	=item unsigned int ev_supported_backends ()
		81
		82	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>
		83	value) compiled into this binary of libev (independent of their
		84	availability on the system you are running on). See C<ev_default_loop> for
		85	a description of the set values.
		86
		87	=item unsigned int ev_recommended_backends ()
		88
		89	Return the set of all backends compiled into this binary of libev and also
		90	recommended for this platform. This set is often smaller than the one
		91	returned by C<ev_supported_backends>, as for example kqueue is broken on
		92	most BSDs and will not be autodetected unless you explicitly request it
		93	(assuming you know what you are doing). This is the set of backends that
		94	C<EVFLAG_AUTO> will probe for.
		95
80	=item ev_set_allocator (void (cb)(void *ptr, long size))	96	=item ev_set_allocator (void (cb)(void *ptr, long size))
81		97
82	Sets the allocation function to use (the prototype is similar to the	98	Sets the allocation function to use (the prototype is similar to the
83	realloc C function, the semantics are identical). It is used to allocate	99	realloc C function, the semantics are identical). It is used to allocate
84	and free memory (no surprises here). If it returns zero when memory	100	and free memory (no surprises here). If it returns zero when memory
…		…
119	=item struct ev_loop *ev_default_loop (unsigned int flags)	135	=item struct ev_loop *ev_default_loop (unsigned int flags)
120		136
121	This will initialise the default event loop if it hasn't been initialised	137	This will initialise the default event loop if it hasn't been initialised
122	yet and return it. If the default loop could not be initialised, returns	138	yet and return it. If the default loop could not be initialised, returns
123	false. If it already was initialised it simply returns it (and ignores the	139	false. If it already was initialised it simply returns it (and ignores the
124	flags).	140	flags. If that is troubling you, check C<ev_backend ()> afterwards).
125		141
126	If you don't know what event loop to use, use the one returned from this	142	If you don't know what event loop to use, use the one returned from this
127	function.	143	function.
128		144
129	The flags argument can be used to specify special behaviour or specific	145	The flags argument can be used to specify special behaviour or specific
130	backends to use, and is usually specified as 0 (or EVFLAG_AUTO).	146	backends to use, and is usually specified as C<0> (or EVFLAG_AUTO).
131		147
132	It supports the following flags:	148	It supports the following flags:
133		149
134	=over 4	150	=over 4
135		151
…		…
145	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	161	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
146	override the flags completely if it is found in the environment. This is	162	override the flags completely if it is found in the environment. This is
147	useful to try out specific backends to test their performance, or to work	163	useful to try out specific backends to test their performance, or to work
148	around bugs.	164	around bugs.
149		165
150	=item C<EVMETHOD_SELECT> (portable select backend)	166	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
151		167
		168	This is your standard select(2) backend. Not I<completely> standard, as
		169	libev tries to roll its own fd_set with no limits on the number of fds,
		170	but if that fails, expect a fairly low limit on the number of fds when
		171	using this backend. It doesn't scale too well (O(highest_fd)), but its usually
		172	the fastest backend for a low number of fds.
		173
152	=item C<EVMETHOD_POLL> (poll backend, available everywhere except on windows)	174	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
153		175
154	=item C<EVMETHOD_EPOLL> (linux only)	176	And this is your standard poll(2) backend. It's more complicated than
		177	select, but handles sparse fds better and has no artificial limit on the
		178	number of fds you can use (except it will slow down considerably with a
		179	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
155		180
156	=item C<EVMETHOD_KQUEUE> (some bsds only)	181	=item C<EVBACKEND_EPOLL> (value 4, Linux)
157		182
158	=item C<EVMETHOD_DEVPOLL> (solaris 8 only)	183	For few fds, this backend is a bit little slower than poll and select,
		184	but it scales phenomenally better. While poll and select usually scale like
		185	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales
		186	either O(1) or O(active_fds).
159		187
160	=item C<EVMETHOD_PORT> (solaris 10 only)	188	While stopping and starting an I/O watcher in the same iteration will
		189	result in some caching, there is still a syscall per such incident
		190	(because the fd could point to a different file description now), so its
		191	best to avoid that. Also, dup()ed file descriptors might not work very
		192	well if you register events for both fds.
		193
		194	Please note that epoll sometimes generates spurious notifications, so you
		195	need to use non-blocking I/O or other means to avoid blocking when no data
		196	(or space) is available.
		197
		198	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
		199
		200	Kqueue deserves special mention, as at the time of this writing, it
		201	was broken on all BSDs except NetBSD (usually it doesn't work with
		202	anything but sockets and pipes, except on Darwin, where of course its
		203	completely useless). For this reason its not being "autodetected" unless
		204	you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO).
		205
		206	It scales in the same way as the epoll backend, but the interface to the
		207	kernel is more efficient (which says nothing about its actual speed, of
		208	course). While starting and stopping an I/O watcher does not cause an
		209	extra syscall as with epoll, it still adds up to four event changes per
		210	incident, so its best to avoid that.
		211
		212	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
		213
		214	This is not implemented yet (and might never be).
		215
		216	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
		217
		218	This uses the Solaris 10 port mechanism. As with everything on Solaris,
		219	it's really slow, but it still scales very well (O(active_fds)).
		220
		221	Please note that solaris ports can result in a lot of spurious
		222	notifications, so you need to use non-blocking I/O or other means to avoid
		223	blocking when no data (or space) is available.
		224
		225	=item C<EVBACKEND_ALL>
		226
		227	Try all backends (even potentially broken ones that wouldn't be tried
		228	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
		229	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
		230
		231	=back
161		232
162	If one or more of these are ored into the flags value, then only these	233	If one or more of these are ored into the flags value, then only these
163	backends will be tried (in the reverse order as given here). If one are	234	backends will be tried (in the reverse order as given here). If none are
164	specified, any backend will do.	235	specified, most compiled-in backend will be tried, usually in reverse
165		236	order of their flag values :)
166	=back
167		237
168	=item struct ev_loop *ev_loop_new (unsigned int flags)	238	=item struct ev_loop *ev_loop_new (unsigned int flags)
169		239
170	Similar to C<ev_default_loop>, but always creates a new event loop that is	240	Similar to C<ev_default_loop>, but always creates a new event loop that is
171	always distinct from the default loop. Unlike the default loop, it cannot	241	always distinct from the default loop. Unlike the default loop, it cannot
…		…
188	This function reinitialises the kernel state for backends that have	258	This function reinitialises the kernel state for backends that have
189	one. Despite the name, you can call it anytime, but it makes most sense	259	one. Despite the name, you can call it anytime, but it makes most sense
190	after forking, in either the parent or child process (or both, but that	260	after forking, in either the parent or child process (or both, but that
191	again makes little sense).	261	again makes little sense).
192		262
193	You I<must> call this function after forking if and only if you want to	263	You I<must> call this function in the child process after forking if and
194	use the event library in both processes. If you just fork+exec, you don't	264	only if you want to use the event library in both processes. If you just
195	have to call it.	265	fork+exec, you don't have to call it.
196		266
197	The function itself is quite fast and it's usually not a problem to call	267	The function itself is quite fast and it's usually not a problem to call
198	it just in case after a fork. To make this easy, the function will fit in	268	it just in case after a fork. To make this easy, the function will fit in
199	quite nicely into a call to C<pthread_atfork>:	269	quite nicely into a call to C<pthread_atfork>:
200		270
201	pthread_atfork (0, 0, ev_default_fork);	271	pthread_atfork (0, 0, ev_default_fork);
202		272
		273	At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use
		274	without calling this function, so if you force one of those backends you
		275	do not need to care.
		276
203	=item ev_loop_fork (loop)	277	=item ev_loop_fork (loop)
204		278
205	Like C<ev_default_fork>, but acts on an event loop created by	279	Like C<ev_default_fork>, but acts on an event loop created by
206	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	280	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
207	after fork, and how you do this is entirely your own problem.	281	after fork, and how you do this is entirely your own problem.
208		282
209	=item unsigned int ev_method (loop)	283	=item unsigned int ev_backend (loop)
210		284
211	Returns one of the C<EVMETHOD_*> flags indicating the event backend in	285	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
212	use.	286	use.
213		287
214	=item ev_tstamp ev_now (loop)	288	=item ev_tstamp ev_now (loop)
215		289
216	Returns the current "event loop time", which is the time the event loop	290	Returns the current "event loop time", which is the time the event loop
…		…
238	one iteration of the loop.	312	one iteration of the loop.
239		313
240	This flags value could be used to implement alternative looping	314	This flags value could be used to implement alternative looping
241	constructs, but the C<prepare> and C<check> watchers provide a better and	315	constructs, but the C<prepare> and C<check> watchers provide a better and
242	more generic mechanism.	316	more generic mechanism.
		317
		318	Here are the gory details of what ev_loop does:
		319
		320	1. If there are no active watchers (reference count is zero), return.
		321	2. Queue and immediately call all prepare watchers.
		322	3. If we have been forked, recreate the kernel state.
		323	4. Update the kernel state with all outstanding changes.
		324	5. Update the "event loop time".
		325	6. Calculate for how long to block.
		326	7. Block the process, waiting for events.
		327	8. Update the "event loop time" and do time jump handling.
		328	9. Queue all outstanding timers.
		329	10. Queue all outstanding periodics.
		330	11. If no events are pending now, queue all idle watchers.
		331	12. Queue all check watchers.
		332	13. Call all queued watchers in reverse order (i.e. check watchers first).
		333	14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
		334	was used, return, otherwise continue with step #1.
243		335
244	=item ev_unloop (loop, how)	336	=item ev_unloop (loop, how)
245		337
246	Can be used to make a call to C<ev_loop> return early (but only after it	338	Can be used to make a call to C<ev_loop> return early (but only after it
247	has processed all outstanding events). The C<how> argument must be either	339	has processed all outstanding events). The C<how> argument must be either
…		…
304	*) >>), and you can stop watching for events at any time by calling the	396	*) >>), and you can stop watching for events at any time by calling the
305	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.	397	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.
306		398
307	As long as your watcher is active (has been started but not stopped) you	399	As long as your watcher is active (has been started but not stopped) you
308	must not touch the values stored in it. Most specifically you must never	400	must not touch the values stored in it. Most specifically you must never
309	reinitialise it or call its set method.	401	reinitialise it or call its set macro.
310		402
311	You can check whether an event is active by calling the C<ev_is_active	403	You can check whether an event is active by calling the C<ev_is_active
312	(watcher *)> macro. To see whether an event is outstanding (but the	404	(watcher *)> macro. To see whether an event is outstanding (but the
313	callback for it has not been called yet) you can use the C<ev_is_pending	405	callback for it has not been called yet) you can use the C<ev_is_pending
314	(watcher *)> macro.	406	(watcher *)> macro.
…		…
431	descriptors correctly if you register interest in two or more fds pointing	523	descriptors correctly if you register interest in two or more fds pointing
432	to the same underlying file/socket etc. description (that is, they share	524	to the same underlying file/socket etc. description (that is, they share
433	the same underlying "file open").	525	the same underlying "file open").
434		526
435	If you must do this, then force the use of a known-to-be-good backend	527	If you must do this, then force the use of a known-to-be-good backend
436	(at the time of this writing, this includes only EVMETHOD_SELECT and	528	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
437	EVMETHOD_POLL).	529	C<EVBACKEND_POLL>).
438		530
439	=over 4	531	=over 4
440		532
441	=item ev_io_init (ev_io *, callback, int fd, int events)	533	=item ev_io_init (ev_io *, callback, int fd, int events)
442		534
…		…
444		536
445	Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive	537	Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive
446	events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ \|	538	events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ \|
447	EV_WRITE> to receive the given events.	539	EV_WRITE> to receive the given events.
448		540
		541	Please note that most of the more scalable backend mechanisms (for example
		542	epoll and solaris ports) can result in spurious readyness notifications
		543	for file descriptors, so you practically need to use non-blocking I/O (and
		544	treat callback invocation as hint only), or retest separately with a safe
		545	interface before doing I/O (XLib can do this), or force the use of either
		546	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this
		547	problem. Also note that it is quite easy to have your callback invoked
		548	when the readyness condition is no longer valid even when employing
		549	typical ways of handling events, so its a good idea to use non-blocking
		550	I/O unconditionally.
		551
449	=back	552	=back
450		553
451	=head2 C<ev_timer> - relative and optionally recurring timeouts	554	=head2 C<ev_timer> - relative and optionally recurring timeouts
452		555
453	Timer watchers are simple relative timers that generate an event after a	556	Timer watchers are simple relative timers that generate an event after a
454	given time, and optionally repeating in regular intervals after that.	557	given time, and optionally repeating in regular intervals after that.
455		558
456	The timers are based on real time, that is, if you register an event that	559	The timers are based on real time, that is, if you register an event that
457	times out after an hour and you reset your system clock to last years	560	times out after an hour and you reset your system clock to last years
458	time, it will still time out after (roughly) and hour. "Roughly" because	561	time, it will still time out after (roughly) and hour. "Roughly" because
459	detecting time jumps is hard, and soem inaccuracies are unavoidable (the	562	detecting time jumps is hard, and some inaccuracies are unavoidable (the
460	monotonic clock option helps a lot here).	563	monotonic clock option helps a lot here).
461		564
462	The relative timeouts are calculated relative to the C<ev_now ()>	565	The relative timeouts are calculated relative to the C<ev_now ()>
463	time. This is usually the right thing as this timestamp refers to the time	566	time. This is usually the right thing as this timestamp refers to the time
464	of the event triggering whatever timeout you are modifying/starting. If	567	of the event triggering whatever timeout you are modifying/starting. If
465	you suspect event processing to be delayed and you need to base the timeout	568	you suspect event processing to be delayed and you I<need> to base the timeout
466	on the current time, use something like this to adjust for this:	569	on the current time, use something like this to adjust for this:
467		570
468	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	571	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
		572
		573	The callback is guarenteed to be invoked only when its timeout has passed,
		574	but if multiple timers become ready during the same loop iteration then
		575	order of execution is undefined.
469		576
470	=over 4	577	=over 4
471		578
472	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	579	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
473		580
…		…
520	again).	627	again).
521		628
522	They can also be used to implement vastly more complex timers, such as	629	They can also be used to implement vastly more complex timers, such as
523	triggering an event on eahc midnight, local time.	630	triggering an event on eahc midnight, local time.
524		631
		632	As with timers, the callback is guarenteed to be invoked only when the
		633	time (C<at>) has been passed, but if multiple periodic timers become ready
		634	during the same loop iteration then order of execution is undefined.
		635
525	=over 4	636	=over 4
526		637
527	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	638	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
528		639
529	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	640	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
530		641
531	Lots of arguments, lets sort it out... There are basically three modes of	642	Lots of arguments, lets sort it out... There are basically three modes of
532	operation, and we will explain them from simplest to complex:	643	operation, and we will explain them from simplest to complex:
533
534		644
535	=over 4	645	=over 4
536		646
537	=item * absolute timer (interval = reschedule_cb = 0)	647	=item * absolute timer (interval = reschedule_cb = 0)
538		648

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Comparing libev/ev.pod (file contents): Revision 1.26 by root, Tue Nov 13 03:11:57 2007 UTC vs. Revision 1.32 by root, Fri Nov 23 08:36:35 2007 UTC

Diff Legend

Comparing libev/ev.pod (file contents):
Revision 1.26 by root, Tue Nov 13 03:11:57 2007 UTC vs.
Revision 1.32 by root, Fri Nov 23 08:36:35 2007 UTC