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

Comparing libev/ev.pod (file contents):
Revision 1.22 by root, Mon Nov 12 18:36:42 2007 UTC vs.
Revision 1.32 by root, Fri Nov 23 08:36:35 2007 UTC

…		…
56		56
57	=over 4	57	=over 4
58		58
59	=item ev_tstamp ev_time ()	59	=item ev_tstamp ev_time ()
60		60
61	Returns the current time as libev would use it.	61	Returns the current time as libev would use it. Please note that the
		62	C<ev_now> function is usually faster and also often returns the timestamp
		63	you actually want to know.
62		64
63	=item int ev_version_major ()	65	=item int ev_version_major ()
64		66
65	=item int ev_version_minor ()	67	=item int ev_version_minor ()
66		68
…		…
72		74
73	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,
74	as this indicates an incompatible change. Minor versions are usually	76	as this indicates an incompatible change. Minor versions are usually
75	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
76	not a problem.	78	not a problem.
		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.
77		95
78	=item ev_set_allocator (void (cb)(void *ptr, long size))	96	=item ev_set_allocator (void (cb)(void *ptr, long size))
79		97
80	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
81	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
…		…
117	=item struct ev_loop *ev_default_loop (unsigned int flags)	135	=item struct ev_loop *ev_default_loop (unsigned int flags)
118		136
119	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
120	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
121	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
122	flags).	140	flags. If that is troubling you, check C<ev_backend ()> afterwards).
123		141
124	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
125	function.	143	function.
126		144
127	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
128	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).
129		147
130	It supports the following flags:	148	It supports the following flags:
131		149
132	=over 4	150	=over 4
133		151
…		…
143	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	161	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
144	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
145	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
146	around bugs.	164	around bugs.
147		165
148	=item C<EVMETHOD_SELECT> (portable select backend)	166	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
149		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
150	=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)
151		175
152	=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).
153		180
154	=item C<EVMETHOD_KQUEUE> (some bsds only)	181	=item C<EVBACKEND_EPOLL> (value 4, Linux)
155		182
156	=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).
157		187
158	=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
159		232
160	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
161	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
162	specified, any backend will do.	235	specified, most compiled-in backend will be tried, usually in reverse
163		236	order of their flag values :)
164	=back
165		237
166	=item struct ev_loop *ev_loop_new (unsigned int flags)	238	=item struct ev_loop *ev_loop_new (unsigned int flags)
167		239
168	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
169	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
…		…
186	This function reinitialises the kernel state for backends that have	258	This function reinitialises the kernel state for backends that have
187	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
188	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
189	again makes little sense).	261	again makes little sense).
190		262
191	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
192	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
193	have to call it.	265	fork+exec, you don't have to call it.
194		266
195	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
196	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
197	quite nicely into a call to C<pthread_atfork>:	269	quite nicely into a call to C<pthread_atfork>:
198		270
199	pthread_atfork (0, 0, ev_default_fork);	271	pthread_atfork (0, 0, ev_default_fork);
200		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
201	=item ev_loop_fork (loop)	277	=item ev_loop_fork (loop)
202		278
203	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
204	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
205	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.
206		282
207	=item unsigned int ev_method (loop)	283	=item unsigned int ev_backend (loop)
208		284
209	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
210	use.	286	use.
211		287
212	=item ev_tstamp ev_now (loop)	288	=item ev_tstamp ev_now (loop)
213		289
214	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
…		…
237		313
238	This flags value could be used to implement alternative looping	314	This flags value could be used to implement alternative looping
239	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
240	more generic mechanism.	316	more generic mechanism.
241		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.
		335
242	=item ev_unloop (loop, how)	336	=item ev_unloop (loop, how)
243		337
244	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
245	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
246	C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop> call return, or	340	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or
247	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	341	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.
248		342
249	=item ev_ref (loop)	343	=item ev_ref (loop)
250		344
251	=item ev_unref (loop)	345	=item ev_unref (loop)
…		…
302	*) >>), 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
303	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.	397	corresponding stop function (C<< ev_<type>_stop (loop, watcher *) >>.
304		398
305	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
306	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
307	reinitialise it or call its set method.	401	reinitialise it or call its set macro.
308		402
309	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
310	(watcher *)> macro. To see whether an event is outstanding (but the	404	(watcher *)> macro. To see whether an event is outstanding (but the
311	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
312	(watcher *)> macro.	406	(watcher *)> macro.
…		…
417	in each iteration of the event loop (This behaviour is called	511	in each iteration of the event loop (This behaviour is called
418	level-triggering because you keep receiving events as long as the	512	level-triggering because you keep receiving events as long as the
419	condition persists. Remember you can stop the watcher if you don't want to	513	condition persists. Remember you can stop the watcher if you don't want to
420	act on the event and neither want to receive future events).	514	act on the event and neither want to receive future events).
421		515
422	In general you can register as many read and/or write event watchers oer	516	In general you can register as many read and/or write event watchers per
423	fd as you want (as long as you don't confuse yourself). Setting all file	517	fd as you want (as long as you don't confuse yourself). Setting all file
424	descriptors to non-blocking mode is also usually a good idea (but not	518	descriptors to non-blocking mode is also usually a good idea (but not
425	required if you know what you are doing).	519	required if you know what you are doing).
426		520
427	You have to be careful with dup'ed file descriptors, though. Some backends	521	You have to be careful with dup'ed file descriptors, though. Some backends
428	(the linux epoll backend is a notable example) cannot handle dup'ed file	522	(the linux epoll backend is a notable example) cannot handle dup'ed file
429	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
430	to the same file/socket etc. description (that is, they share the same	524	to the same underlying file/socket etc. description (that is, they share
431	underlying "file open").	525	the same underlying "file open").
432		526
433	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
434	(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
435	EVMETHOD_POLL).	529	C<EVBACKEND_POLL>).
436		530
437	=over 4	531	=over 4
438		532
439	=item ev_io_init (ev_io *, callback, int fd, int events)	533	=item ev_io_init (ev_io *, callback, int fd, int events)
440		534
…		…
442		536
443	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
444	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 \|
445	EV_WRITE> to receive the given events.	539	EV_WRITE> to receive the given events.
446		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
447	=back	552	=back
448		553
449	=head2 C<ev_timer> - relative and optionally recurring timeouts	554	=head2 C<ev_timer> - relative and optionally recurring timeouts
450		555
451	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
452	given time, and optionally repeating in regular intervals after that.	557	given time, and optionally repeating in regular intervals after that.
453		558
454	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
455	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
456	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
457	detecting time jumps is hard, and soem inaccuracies are unavoidable (the	562	detecting time jumps is hard, and some inaccuracies are unavoidable (the
458	monotonic clock option helps a lot here).	563	monotonic clock option helps a lot here).
459		564
460	The relative timeouts are calculated relative to the C<ev_now ()>	565	The relative timeouts are calculated relative to the C<ev_now ()>
461	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
462	of the event triggering whatever timeout you are modifying/starting. If	567	of the event triggering whatever timeout you are modifying/starting. If
463	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
464	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:
465		570
466	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.
467		576
468	=over 4	577	=over 4
469		578
470	=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)
471		580
…		…
518	again).	627	again).
519		628
520	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
521	triggering an event on eahc midnight, local time.	630	triggering an event on eahc midnight, local time.
522		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
523	=over 4	636	=over 4
524		637
525	=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)
526		639
527	=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)
528		641
529	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
530	operation, and we will explain them from simplest to complex:	643	operation, and we will explain them from simplest to complex:
531
532		644
533	=over 4	645	=over 4
534		646
535	=item * absolute timer (interval = reschedule_cb = 0)	647	=item * absolute timer (interval = reschedule_cb = 0)
536		648
…		…
772		884
773	=back	885	=back
774		886
775	=head1 LIBEVENT EMULATION	887	=head1 LIBEVENT EMULATION
776		888
		889	Libev offers a compatibility emulation layer for libevent. It cannot
		890	emulate the internals of libevent, so here are some usage hints:
		891
		892	=over 4
		893
		894	=item * Use it by including <event.h>, as usual.
		895
		896	=item * The following members are fully supported: ev_base, ev_callback,
		897	ev_arg, ev_fd, ev_res, ev_events.
		898
		899	=item * Avoid using ev_flags and the EVLIST_*-macros, while it is
		900	maintained by libev, it does not work exactly the same way as in libevent (consider
		901	it a private API).
		902
		903	=item * Priorities are not currently supported. Initialising priorities
		904	will fail and all watchers will have the same priority, even though there
		905	is an ev_pri field.
		906
		907	=item * Other members are not supported.
		908
		909	=item * The libev emulation is I<not> ABI compatible to libevent, you need
		910	to use the libev header file and library.
		911
		912	=back
		913
		914	=head1 C++ SUPPORT
		915
777	TBD.	916	TBD.
778		917
779	=head1 C++ SUPPORT
780
781	TBD.
782
783	=head1 AUTHOR	918	=head1 AUTHOR
784		919
785	Marc Lehmann <libev@schmorp.de>.	920	Marc Lehmann <libev@schmorp.de>.
786		921

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing libev/ev.pod (file contents): Revision 1.22 by root, Mon Nov 12 18:36:42 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 1.22 by root, Mon Nov 12 18:36:42 2007 UTC vs.
Revision 1.32 by root, Fri Nov 23 08:36:35 2007 UTC