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

Comparing libev/ev.pod (file contents):
Revision 1.17 by root, Mon Nov 12 08:57:03 2007 UTC vs.
Revision 1.28 by root, Sat Nov 17 02:00:49 2007 UTC

…		…
49	called C<ev_tstamp>, which is what you should use too. It usually aliases	49	called C<ev_tstamp>, which is what you should use too. It usually aliases
50	to the double type in C.	50	to the double type in C.
51		51
52	=head1 GLOBAL FUNCTIONS	52	=head1 GLOBAL FUNCTIONS
53		53
		54	These functions can be called anytime, even before initialising the
		55	library in any way.
		56
54	=over 4	57	=over 4
55		58
56	=item ev_tstamp ev_time ()	59	=item ev_tstamp ev_time ()
57		60
58	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.
59		64
60	=item int ev_version_major ()	65	=item int ev_version_major ()
61		66
62	=item int ev_version_minor ()	67	=item int ev_version_minor ()
63		68
…		…
234		239
235	This flags value could be used to implement alternative looping	240	This flags value could be used to implement alternative looping
236	constructs, but the C<prepare> and C<check> watchers provide a better and	241	constructs, but the C<prepare> and C<check> watchers provide a better and
237	more generic mechanism.	242	more generic mechanism.
238		243
		244	Here are the gory details of what ev_loop does:
		245
		246	1. If there are no active watchers (reference count is zero), return.
		247	2. Queue and immediately call all prepare watchers.
		248	3. If we have been forked, recreate the kernel state.
		249	4. Update the kernel state with all outstanding changes.
		250	5. Update the "event loop time".
		251	6. Calculate for how long to block.
		252	7. Block the process, waiting for events.
		253	8. Update the "event loop time" and do time jump handling.
		254	9. Queue all outstanding timers.
		255	10. Queue all outstanding periodics.
		256	11. If no events are pending now, queue all idle watchers.
		257	12. Queue all check watchers.
		258	13. Call all queued watchers in reverse order (i.e. check watchers first).
		259	14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
		260	was used, return, otherwise continue with step #1.
		261
239	=item ev_unloop (loop, how)	262	=item ev_unloop (loop, how)
240		263
241	Can be used to make a call to C<ev_loop> return early (but only after it	264	Can be used to make a call to C<ev_loop> return early (but only after it
242	has processed all outstanding events). The C<how> argument must be either	265	has processed all outstanding events). The C<how> argument must be either
243	C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop> call return, or	266	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or
244	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	267	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.
245		268
246	=item ev_ref (loop)	269	=item ev_ref (loop)
247		270
248	=item ev_unref (loop)	271	=item ev_unref (loop)
…		…
414	in each iteration of the event loop (This behaviour is called	437	in each iteration of the event loop (This behaviour is called
415	level-triggering because you keep receiving events as long as the	438	level-triggering because you keep receiving events as long as the
416	condition persists. Remember you can stop the watcher if you don't want to	439	condition persists. Remember you can stop the watcher if you don't want to
417	act on the event and neither want to receive future events).	440	act on the event and neither want to receive future events).
418		441
419	In general you can register as many read and/or write event watchers oer	442	In general you can register as many read and/or write event watchers per
420	fd as you want (as long as you don't confuse yourself). Setting all file	443	fd as you want (as long as you don't confuse yourself). Setting all file
421	descriptors to non-blocking mode is also usually a good idea (but not	444	descriptors to non-blocking mode is also usually a good idea (but not
422	required if you know what you are doing).	445	required if you know what you are doing).
423		446
424	You have to be careful with dup'ed file descriptors, though. Some backends	447	You have to be careful with dup'ed file descriptors, though. Some backends
425	(the linux epoll backend is a notable example) cannot handle dup'ed file	448	(the linux epoll backend is a notable example) cannot handle dup'ed file
426	descriptors correctly if you register interest in two or more fds pointing	449	descriptors correctly if you register interest in two or more fds pointing
427	to the same file/socket etc. description.	450	to the same underlying file/socket etc. description (that is, they share
		451	the same underlying "file open").
428		452
429	If you must do this, then force the use of a known-to-be-good backend	453	If you must do this, then force the use of a known-to-be-good backend
430	(at the time of this writing, this includes only EVMETHOD_SELECT and	454	(at the time of this writing, this includes only EVMETHOD_SELECT and
431	EVMETHOD_POLL).	455	EVMETHOD_POLL).
432		456
…		…
446		470
447	Timer watchers are simple relative timers that generate an event after a	471	Timer watchers are simple relative timers that generate an event after a
448	given time, and optionally repeating in regular intervals after that.	472	given time, and optionally repeating in regular intervals after that.
449		473
450	The timers are based on real time, that is, if you register an event that	474	The timers are based on real time, that is, if you register an event that
451	times out after an hour and youreset your system clock to last years	475	times out after an hour and you reset your system clock to last years
452	time, it will still time out after (roughly) and hour. "Roughly" because	476	time, it will still time out after (roughly) and hour. "Roughly" because
453	detecting time jumps is hard, and soem inaccuracies are unavoidable (the	477	detecting time jumps is hard, and some inaccuracies are unavoidable (the
454	monotonic clock option helps a lot here).	478	monotonic clock option helps a lot here).
455		479
456	The relative timeouts are calculated relative to the C<ev_now ()>	480	The relative timeouts are calculated relative to the C<ev_now ()>
457	time. This is usually the right thing as this timestamp refers to the time	481	time. This is usually the right thing as this timestamp refers to the time
458	of the event triggering whatever timeout you are modifying/starting. If	482	of the event triggering whatever timeout you are modifying/starting. If
459	you suspect event processing to be delayed and you need to base the timeout	483	you suspect event processing to be delayed and you I<need> to base the timeout
460	ion the current time, use something like this to adjust for this:	484	on the current time, use something like this to adjust for this:
461		485
462	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	486	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
		487
		488	The callback is guarenteed to be invoked only when its timeout has passed,
		489	but if multiple timers become ready during the same loop iteration then
		490	order of execution is undefined.
463		491
464	=over 4	492	=over 4
465		493
466	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	494	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
467		495
…		…
473	later, again, and again, until stopped manually.	501	later, again, and again, until stopped manually.
474		502
475	The timer itself will do a best-effort at avoiding drift, that is, if you	503	The timer itself will do a best-effort at avoiding drift, that is, if you
476	configure a timer to trigger every 10 seconds, then it will trigger at	504	configure a timer to trigger every 10 seconds, then it will trigger at
477	exactly 10 second intervals. If, however, your program cannot keep up with	505	exactly 10 second intervals. If, however, your program cannot keep up with
478	the timer (ecause it takes longer than those 10 seconds to do stuff) the	506	the timer (because it takes longer than those 10 seconds to do stuff) the
479	timer will not fire more than once per event loop iteration.	507	timer will not fire more than once per event loop iteration.
480		508
481	=item ev_timer_again (loop)	509	=item ev_timer_again (loop)
482		510
483	This will act as if the timer timed out and restart it again if it is	511	This will act as if the timer timed out and restart it again if it is
…		…
514	again).	542	again).
515		543
516	They can also be used to implement vastly more complex timers, such as	544	They can also be used to implement vastly more complex timers, such as
517	triggering an event on eahc midnight, local time.	545	triggering an event on eahc midnight, local time.
518		546
		547	As with timers, the callback is guarenteed to be invoked only when the
		548	time (C<at>) has been passed, but if multiple periodic timers become ready
		549	during the same loop iteration then order of execution is undefined.
		550
519	=over 4	551	=over 4
520		552
521	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	553	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
522		554
523	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	555	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
524		556
525	Lots of arguments, lets sort it out... There are basically three modes of	557	Lots of arguments, lets sort it out... There are basically three modes of
526	operation, and we will explain them from simplest to complex:	558	operation, and we will explain them from simplest to complex:
527
528		559
529	=over 4	560	=over 4
530		561
531	=item * absolute timer (interval = reschedule_cb = 0)	562	=item * absolute timer (interval = reschedule_cb = 0)
532		563
…		…
560	In this mode the values for C<interval> and C<at> are both being	591	In this mode the values for C<interval> and C<at> are both being
561	ignored. Instead, each time the periodic watcher gets scheduled, the	592	ignored. Instead, each time the periodic watcher gets scheduled, the
562	reschedule callback will be called with the watcher as first, and the	593	reschedule callback will be called with the watcher as first, and the
563	current time as second argument.	594	current time as second argument.
564		595
565	NOTE: I<This callback MUST NOT stop or destroy the periodic or any other	596	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
566	periodic watcher, ever, or make any event loop modifications>. If you need	597	ever, or make any event loop modifications>. If you need to stop it,
567	to stop it, return C<now + 1e30> (or so, fudge fudge) and stop it afterwards.	598	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
568		599	starting a prepare watcher).
569	Also, I<< this callback must always return a time that is later than the
570	passed C<now> value >>. Not even C<now> itself will be ok.
571		600
572	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	601	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
573	ev_tstamp now)>, e.g.:	602	ev_tstamp now)>, e.g.:
574		603
575	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	604	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
580	It must return the next time to trigger, based on the passed time value	609	It must return the next time to trigger, based on the passed time value
581	(that is, the lowest time value larger than to the second argument). It	610	(that is, the lowest time value larger than to the second argument). It
582	will usually be called just before the callback will be triggered, but	611	will usually be called just before the callback will be triggered, but
583	might be called at other times, too.	612	might be called at other times, too.
584		613
		614	NOTE: I<< This callback must always return a time that is later than the
		615	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.
		616
585	This can be used to create very complex timers, such as a timer that	617	This can be used to create very complex timers, such as a timer that
586	triggers on each midnight, local time. To do this, you would calculate the	618	triggers on each midnight, local time. To do this, you would calculate the
587	next midnight after C<now> and return the timestamp value for this. How you do this	619	next midnight after C<now> and return the timestamp value for this. How
588	is, again, up to you (but it is not trivial).	620	you do this is, again, up to you (but it is not trivial, which is the main
		621	reason I omitted it as an example).
589		622
590	=back	623	=back
591		624
592	=item ev_periodic_again (loop, ev_periodic *)	625	=item ev_periodic_again (loop, ev_periodic *)
593		626
…		…
672	=back	705	=back
673		706
674	=head2 C<ev_prepare> and C<ev_check> - customise your event loop	707	=head2 C<ev_prepare> and C<ev_check> - customise your event loop
675		708
676	Prepare and check watchers are usually (but not always) used in tandem:	709	Prepare and check watchers are usually (but not always) used in tandem:
677	Prepare watchers get invoked before the process blocks and check watchers	710	prepare watchers get invoked before the process blocks and check watchers
678	afterwards.	711	afterwards.
679		712
680	Their main purpose is to integrate other event mechanisms into libev. This	713	Their main purpose is to integrate other event mechanisms into libev. This
681	could be used, for example, to track variable changes, implement your own	714	could be used, for example, to track variable changes, implement your own
682	watchers, integrate net-snmp or a coroutine library and lots more.	715	watchers, integrate net-snmp or a coroutine library and lots more.
…		…
685	to be watched by the other library, registering C<ev_io> watchers for	718	to be watched by the other library, registering C<ev_io> watchers for
686	them and starting an C<ev_timer> watcher for any timeouts (many libraries	719	them and starting an C<ev_timer> watcher for any timeouts (many libraries
687	provide just this functionality). Then, in the check watcher you check for	720	provide just this functionality). Then, in the check watcher you check for
688	any events that occured (by checking the pending status of all watchers	721	any events that occured (by checking the pending status of all watchers
689	and stopping them) and call back into the library. The I/O and timer	722	and stopping them) and call back into the library. The I/O and timer
690	callbacks will never actually be called (but must be valid neverthelles,	723	callbacks will never actually be called (but must be valid nevertheless,
691	because you never know, you know?).	724	because you never know, you know?).
692		725
693	As another example, the Perl Coro module uses these hooks to integrate	726	As another example, the Perl Coro module uses these hooks to integrate
694	coroutines into libev programs, by yielding to other active coroutines	727	coroutines into libev programs, by yielding to other active coroutines
695	during each prepare and only letting the process block if no coroutines	728	during each prepare and only letting the process block if no coroutines
696	are ready to run (its actually more complicated, it only runs coroutines	729	are ready to run (it's actually more complicated: it only runs coroutines
697	with priority higher than the event loop and one lower priority once,	730	with priority higher than or equal to the event loop and one coroutine
698	using idle watchers to keep the event loop from blocking if lower-priority	731	of lower priority, but only once, using idle watchers to keep the event
699	coroutines exist, thus mapping low-priority coroutines to idle/background	732	loop from blocking if lower-priority coroutines are active, thus mapping
700	tasks).	733	low-priority coroutines to idle/background tasks).
701		734
702	=over 4	735	=over 4
703		736
704	=item ev_prepare_init (ev_prepare *, callback)	737	=item ev_prepare_init (ev_prepare *, callback)
705		738
…		…
720	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)	753	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)
721		754
722	This function combines a simple timer and an I/O watcher, calls your	755	This function combines a simple timer and an I/O watcher, calls your
723	callback on whichever event happens first and automatically stop both	756	callback on whichever event happens first and automatically stop both
724	watchers. This is useful if you want to wait for a single event on an fd	757	watchers. This is useful if you want to wait for a single event on an fd
725	or timeout without havign to allocate/configure/start/stop/free one or	758	or timeout without having to allocate/configure/start/stop/free one or
726	more watchers yourself.	759	more watchers yourself.
727		760
728	If C<fd> is less than 0, then no I/O watcher will be started and events	761	If C<fd> is less than 0, then no I/O watcher will be started and events
729	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	762	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
730	C<events> set will be craeted and started.	763	C<events> set will be craeted and started.
…		…
733	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	766	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
734	repeat = 0) will be started. While C<0> is a valid timeout, it is of	767	repeat = 0) will be started. While C<0> is a valid timeout, it is of
735	dubious value.	768	dubious value.
736		769
737	The callback has the type C<void (cb)(int revents, void arg)> and gets	770	The callback has the type C<void (cb)(int revents, void arg)> and gets
738	passed an events set like normal event callbacks (with a combination of	771	passed an C<revents> set like normal event callbacks (a combination of
739	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	772	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
740	value passed to C<ev_once>:	773	value passed to C<ev_once>:
741		774
742	static void stdin_ready (int revents, void *arg)	775	static void stdin_ready (int revents, void *arg)
743	{	776	{
…		…
764		797
765	Feed an event as if the given signal occured (loop must be the default loop!).	798	Feed an event as if the given signal occured (loop must be the default loop!).
766		799
767	=back	800	=back
768		801
		802	=head1 LIBEVENT EMULATION
		803
		804	Libev offers a compatibility emulation layer for libevent. It cannot
		805	emulate the internals of libevent, so here are some usage hints:
		806
		807	=over 4
		808
		809	=item * Use it by including <event.h>, as usual.
		810
		811	=item * The following members are fully supported: ev_base, ev_callback,
		812	ev_arg, ev_fd, ev_res, ev_events.
		813
		814	=item * Avoid using ev_flags and the EVLIST_*-macros, while it is
		815	maintained by libev, it does not work exactly the same way as in libevent (consider
		816	it a private API).
		817
		818	=item * Priorities are not currently supported. Initialising priorities
		819	will fail and all watchers will have the same priority, even though there
		820	is an ev_pri field.
		821
		822	=item * Other members are not supported.
		823
		824	=item * The libev emulation is I<not> ABI compatible to libevent, you need
		825	to use the libev header file and library.
		826
		827	=back
		828
		829	=head1 C++ SUPPORT
		830
		831	TBD.
		832
769	=head1 AUTHOR	833	=head1 AUTHOR
770		834
771	Marc Lehmann <libev@schmorp.de>.	835	Marc Lehmann <libev@schmorp.de>.
772		836

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Comparing libev/ev.pod (file contents): Revision 1.17 by root, Mon Nov 12 08:57:03 2007 UTC vs. Revision 1.28 by root, Sat Nov 17 02:00:49 2007 UTC

Diff Legend

Comparing libev/ev.pod (file contents):
Revision 1.17 by root, Mon Nov 12 08:57:03 2007 UTC vs.
Revision 1.28 by root, Sat Nov 17 02:00:49 2007 UTC