[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 1.26 by root, Tue Nov 13 03:11:57 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
…		…
238		243
239	=item ev_unloop (loop, how)	244	=item ev_unloop (loop, how)
240		245
241	Can be used to make a call to C<ev_loop> return early (but only after it	246	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	247	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	248	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.	249	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.
245		250
246	=item ev_ref (loop)	251	=item ev_ref (loop)
247		252
248	=item ev_unref (loop)	253	=item ev_unref (loop)
…		…
414	in each iteration of the event loop (This behaviour is called	419	in each iteration of the event loop (This behaviour is called
415	level-triggering because you keep receiving events as long as the	420	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	421	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).	422	act on the event and neither want to receive future events).
418		423
419	In general you can register as many read and/or write event watchers oer	424	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	425	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	426	descriptors to non-blocking mode is also usually a good idea (but not
422	required if you know what you are doing).	427	required if you know what you are doing).
423		428
424	You have to be careful with dup'ed file descriptors, though. Some backends	429	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	430	(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	431	descriptors correctly if you register interest in two or more fds pointing
427	to the same file/socket etc. description.	432	to the same underlying file/socket etc. description (that is, they share
		433	the same underlying "file open").
428		434
429	If you must do this, then force the use of a known-to-be-good backend	435	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	436	(at the time of this writing, this includes only EVMETHOD_SELECT and
431	EVMETHOD_POLL).	437	EVMETHOD_POLL).
432		438
…		…
446		452
447	Timer watchers are simple relative timers that generate an event after a	453	Timer watchers are simple relative timers that generate an event after a
448	given time, and optionally repeating in regular intervals after that.	454	given time, and optionally repeating in regular intervals after that.
449		455
450	The timers are based on real time, that is, if you register an event that	456	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	457	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	458	time, it will still time out after (roughly) and hour. "Roughly" because
453	detecting time jumps is hard, and soem inaccuracies are unavoidable (the	459	detecting time jumps is hard, and soem inaccuracies are unavoidable (the
454	monotonic clock option helps a lot here).	460	monotonic clock option helps a lot here).
455		461
456	The relative timeouts are calculated relative to the C<ev_now ()>	462	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	463	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	464	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	465	you suspect event processing to be delayed and you need to base the timeout
460	ion the current time, use something like this to adjust for this:	466	on the current time, use something like this to adjust for this:
461		467
462	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	468	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
463		469
464	=over 4	470	=over 4
465		471
…		…
473	later, again, and again, until stopped manually.	479	later, again, and again, until stopped manually.
474		480
475	The timer itself will do a best-effort at avoiding drift, that is, if you	481	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	482	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	483	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	484	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.	485	timer will not fire more than once per event loop iteration.
480		486
481	=item ev_timer_again (loop)	487	=item ev_timer_again (loop)
482		488
483	This will act as if the timer timed out and restart it again if it is	489	This will act as if the timer timed out and restart it again if it is
…		…
560	In this mode the values for C<interval> and C<at> are both being	566	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	567	ignored. Instead, each time the periodic watcher gets scheduled, the
562	reschedule callback will be called with the watcher as first, and the	568	reschedule callback will be called with the watcher as first, and the
563	current time as second argument.	569	current time as second argument.
564		570
565	NOTE: I<This callback MUST NOT stop or destroy the periodic or any other	571	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	572	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.	573	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
568		574	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		575
572	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,	576	Its prototype is C<ev_tstamp (reschedule_cb)(struct ev_periodic w,
573	ev_tstamp now)>, e.g.:	577	ev_tstamp now)>, e.g.:
574		578
575	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	579	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	584	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	585	(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	586	will usually be called just before the callback will be triggered, but
583	might be called at other times, too.	587	might be called at other times, too.
584		588
		589	NOTE: I<< This callback must always return a time that is later than the
		590	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.
		591
585	This can be used to create very complex timers, such as a timer that	592	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	593	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	594	next midnight after C<now> and return the timestamp value for this. How
588	is, again, up to you (but it is not trivial).	595	you do this is, again, up to you (but it is not trivial, which is the main
		596	reason I omitted it as an example).
589		597
590	=back	598	=back
591		599
592	=item ev_periodic_again (loop, ev_periodic *)	600	=item ev_periodic_again (loop, ev_periodic *)
593		601
…		…
672	=back	680	=back
673		681
674	=head2 C<ev_prepare> and C<ev_check> - customise your event loop	682	=head2 C<ev_prepare> and C<ev_check> - customise your event loop
675		683
676	Prepare and check watchers are usually (but not always) used in tandem:	684	Prepare and check watchers are usually (but not always) used in tandem:
677	Prepare watchers get invoked before the process blocks and check watchers	685	prepare watchers get invoked before the process blocks and check watchers
678	afterwards.	686	afterwards.
679		687
680	Their main purpose is to integrate other event mechanisms into libev. This	688	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	689	could be used, for example, to track variable changes, implement your own
682	watchers, integrate net-snmp or a coroutine library and lots more.	690	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	693	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	694	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	695	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	696	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	697	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,	698	callbacks will never actually be called (but must be valid nevertheless,
691	because you never know, you know?).	699	because you never know, you know?).
692		700
693	As another example, the Perl Coro module uses these hooks to integrate	701	As another example, the Perl Coro module uses these hooks to integrate
694	coroutines into libev programs, by yielding to other active coroutines	702	coroutines into libev programs, by yielding to other active coroutines
695	during each prepare and only letting the process block if no coroutines	703	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	704	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,	705	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	706	of lower priority, but only once, using idle watchers to keep the event
699	coroutines exist, thus mapping low-priority coroutines to idle/background	707	loop from blocking if lower-priority coroutines are active, thus mapping
700	tasks).	708	low-priority coroutines to idle/background tasks).
701		709
702	=over 4	710	=over 4
703		711
704	=item ev_prepare_init (ev_prepare *, callback)	712	=item ev_prepare_init (ev_prepare *, callback)
705		713
…		…
720	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)	728	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)
721		729
722	This function combines a simple timer and an I/O watcher, calls your	730	This function combines a simple timer and an I/O watcher, calls your
723	callback on whichever event happens first and automatically stop both	731	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	732	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	733	or timeout without having to allocate/configure/start/stop/free one or
726	more watchers yourself.	734	more watchers yourself.
727		735
728	If C<fd> is less than 0, then no I/O watcher will be started and events	736	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	737	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
730	C<events> set will be craeted and started.	738	C<events> set will be craeted and started.
…		…
733	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	741	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	742	repeat = 0) will be started. While C<0> is a valid timeout, it is of
735	dubious value.	743	dubious value.
736		744
737	The callback has the type C<void (cb)(int revents, void arg)> and gets	745	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	746	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>	747	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
740	value passed to C<ev_once>:	748	value passed to C<ev_once>:
741		749
742	static void stdin_ready (int revents, void *arg)	750	static void stdin_ready (int revents, void *arg)
743	{	751	{
…		…
764		772
765	Feed an event as if the given signal occured (loop must be the default loop!).	773	Feed an event as if the given signal occured (loop must be the default loop!).
766		774
767	=back	775	=back
768		776
		777	=head1 LIBEVENT EMULATION
		778
		779	Libev offers a compatibility emulation layer for libevent. It cannot
		780	emulate the internals of libevent, so here are some usage hints:
		781
		782	=over 4
		783
		784	=item * Use it by including <event.h>, as usual.
		785
		786	=item * The following members are fully supported: ev_base, ev_callback,
		787	ev_arg, ev_fd, ev_res, ev_events.
		788
		789	=item * Avoid using ev_flags and the EVLIST_*-macros, while it is
		790	maintained by libev, it does not work exactly the same way as in libevent (consider
		791	it a private API).
		792
		793	=item * Priorities are not currently supported. Initialising priorities
		794	will fail and all watchers will have the same priority, even though there
		795	is an ev_pri field.
		796
		797	=item * Other members are not supported.
		798
		799	=item * The libev emulation is I<not> ABI compatible to libevent, you need
		800	to use the libev header file and library.
		801
		802	=back
		803
		804	=head1 C++ SUPPORT
		805
		806	TBD.
		807
769	=head1 AUTHOR	808	=head1 AUTHOR
770		809
771	Marc Lehmann <libev@schmorp.de>.	810	Marc Lehmann <libev@schmorp.de>.
772		811

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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 1.26 by root, Tue Nov 13 03:11:57 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 1.26 by root, Tue Nov 13 03:11:57 2007 UTC