[ViewVC] Diff of: cvs/AnyEvent/lib/AnyEvent.pm

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.320 by root, Mon Apr 12 02:50:31 2010 UTC vs.
Revision 1.331 by root, Tue Aug 31 01:00:48 2010 UTC

…		…
7		7
8	=head1 SYNOPSIS	8	=head1 SYNOPSIS
9		9
10	use AnyEvent;	10	use AnyEvent;
11		11
12	# if you prefer function calls, look at the L<AE> manpage for	12	# if you prefer function calls, look at the AE manpage for
13	# an alternative API.	13	# an alternative API.
14		14
15	# file handle or descriptor readable	15	# file handle or descriptor readable
16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });	16	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
17		17
18	# one-shot or repeating timers	18	# one-shot or repeating timers
19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	19	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	20	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...);
21		21
22	print AnyEvent->now; # prints current event loop time	22	print AnyEvent->now; # prints current event loop time
23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	23	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
24		24
25	# POSIX signal	25	# POSIX signal
…		…
76	module users into the same thing by forcing them to use the same event	76	module users into the same thing by forcing them to use the same event
77	model you use.	77	model you use.
78		78
79	For modules like POE or IO::Async (which is a total misnomer as it is	79	For modules like POE or IO::Async (which is a total misnomer as it is
80	actually doing all I/O I<synchronously>...), using them in your module is	80	actually doing all I/O I<synchronously>...), using them in your module is
81	like joining a cult: After you joined, you are dependent on them and you	81	like joining a cult: After you join, you are dependent on them and you
82	cannot use anything else, as they are simply incompatible to everything	82	cannot use anything else, as they are simply incompatible to everything
83	that isn't them. What's worse, all the potential users of your	83	that isn't them. What's worse, all the potential users of your
84	module are I<also> forced to use the same event loop you use.	84	module are I<also> forced to use the same event loop you use.
85		85
86	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	86	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
87	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	87	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
88	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	88	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
89	your module uses one of those, every user of your module has to use it,	89	your module uses one of those, every user of your module has to use it,
90	too. But if your module uses AnyEvent, it works transparently with all	90	too. But if your module uses AnyEvent, it works transparently with all
91	event models it supports (including stuff like IO::Async, as long as those	91	event models it supports (including stuff like IO::Async, as long as those
92	use one of the supported event loops. It is trivial to add new event loops	92	use one of the supported event loops. It is easy to add new event loops
93	to AnyEvent, too, so it is future-proof).	93	to AnyEvent, too, so it is future-proof).
94		94
95	In addition to being free of having to use I<the one and only true event	95	In addition to being free of having to use I<the one and only true event
96	model>, AnyEvent also is free of bloat and policy: with POE or similar	96	model>, AnyEvent also is free of bloat and policy: with POE or similar
97	modules, you get an enormous amount of code and strict rules you have to	97	modules, you get an enormous amount of code and strict rules you have to
98	follow. AnyEvent, on the other hand, is lean and up to the point, by only	98	follow. AnyEvent, on the other hand, is lean and to the point, by only
99	offering the functionality that is necessary, in as thin as a wrapper as	99	offering the functionality that is necessary, in as thin as a wrapper as
100	technically possible.	100	technically possible.
101		101
102	Of course, AnyEvent comes with a big (and fully optional!) toolbox	102	Of course, AnyEvent comes with a big (and fully optional!) toolbox
103	of useful functionality, such as an asynchronous DNS resolver, 100%	103	of useful functionality, such as an asynchronous DNS resolver, 100%
…		…
109	useful) and you want to force your users to use the one and only event	109	useful) and you want to force your users to use the one and only event
110	model, you should I<not> use this module.	110	model, you should I<not> use this module.
111		111
112	=head1 DESCRIPTION	112	=head1 DESCRIPTION
113		113
114	L<AnyEvent> provides an identical interface to multiple event loops. This	114	L<AnyEvent> provides a uniform interface to various event loops. This
115	allows module authors to utilise an event loop without forcing module	115	allows module authors to use event loop functionality without forcing
116	users to use the same event loop (as only a single event loop can coexist	116	module users to use a specific event loop implementation (since more
117	peacefully at any one time).	117	than one event loop cannot coexist peacefully).
118		118
119	The interface itself is vaguely similar, but not identical to the L<Event>	119	The interface itself is vaguely similar, but not identical to the L<Event>
120	module.	120	module.
121		121
122	During the first call of any watcher-creation method, the module tries	122	During the first call of any watcher-creation method, the module tries
123	to detect the currently loaded event loop by probing whether one of the	123	to detect the currently loaded event loop by probing whether one of the
124	following modules is already loaded: L<EV>,	124	following modules is already loaded: L<EV>, L<AnyEvent::Impl::Perl>,
125	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	125	L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>. The first one
126	L<POE>. The first one found is used. If none are found, the module tries	126	found is used. If none are detected, the module tries to load the first
127	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	127	four modules in the order given; but note that if L<EV> is not
128	adaptor should always succeed) in the order given. The first one that can	128	available, the pure-perl L<AnyEvent::Impl::Perl> should always work, so
129	be successfully loaded will be used. If, after this, still none could be	129	the other two are not normally tried.
130	found, AnyEvent will fall back to a pure-perl event loop, which is not
131	very efficient, but should work everywhere.
132		130
133	Because AnyEvent first checks for modules that are already loaded, loading	131	Because AnyEvent first checks for modules that are already loaded, loading
134	an event model explicitly before first using AnyEvent will likely make	132	an event model explicitly before first using AnyEvent will likely make
135	that model the default. For example:	133	that model the default. For example:
136		134
…		…
138	use AnyEvent;	136	use AnyEvent;
139		137
140	# .. AnyEvent will likely default to Tk	138	# .. AnyEvent will likely default to Tk
141		139
142	The I<likely> means that, if any module loads another event model and	140	The I<likely> means that, if any module loads another event model and
143	starts using it, all bets are off. Maybe you should tell their authors to	141	starts using it, all bets are off - this case should be very rare though,
144	use AnyEvent so their modules work together with others seamlessly...	142	as very few modules hardcode event loops without announcing this very
		143	loudly.
145		144
146	The pure-perl implementation of AnyEvent is called	145	The pure-perl implementation of AnyEvent is called
147	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	146	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
148	explicitly and enjoy the high availability of that event loop :)	147	explicitly and enjoy the high availability of that event loop :)
149		148
…		…
158	callback when the event occurs (of course, only when the event model	157	callback when the event occurs (of course, only when the event model
159	is in control).	158	is in control).
160		159
161	Note that B<callbacks must not permanently change global variables>	160	Note that B<callbacks must not permanently change global variables>
162	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<	161	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
163	callbacks must not C<die> >>. The former is good programming practise in	162	callbacks must not C<die> >>. The former is good programming practice in
164	Perl and the latter stems from the fact that exception handling differs	163	Perl and the latter stems from the fact that exception handling differs
165	widely between event loops.	164	widely between event loops.
166		165
167	To disable the watcher you have to destroy it (e.g. by setting the	166	To disable a watcher you have to destroy it (e.g. by setting the
168	variable you store it in to C<undef> or otherwise deleting all references	167	variable you store it in to C<undef> or otherwise deleting all references
169	to it).	168	to it).
170		169
171	All watchers are created by calling a method on the C<AnyEvent> class.	170	All watchers are created by calling a method on the C<AnyEvent> class.
172		171
173	Many watchers either are used with "recursion" (repeating timers for	172	Many watchers either are used with "recursion" (repeating timers for
174	example), or need to refer to their watcher object in other ways.	173	example), or need to refer to their watcher object in other ways.
175		174
176	An any way to achieve that is this pattern:	175	One way to achieve that is this pattern:
177		176
178	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	177	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
179	# you can use $w here, for example to undef it	178	# you can use $w here, for example to undef it
180	undef $w;	179	undef $w;
181	});	180	});
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213		212
214	The I/O watcher might use the underlying file descriptor or a copy of it.	213	The I/O watcher might use the underlying file descriptor or a copy of it.
215	You must not close a file handle as long as any watcher is active on the	214	You must not close a file handle as long as any watcher is active on the
216	underlying file descriptor.	215	underlying file descriptor.
217		216
218	Some event loops issue spurious readyness notifications, so you should	217	Some event loops issue spurious readiness notifications, so you should
219	always use non-blocking calls when reading/writing from/to your file	218	always use non-blocking calls when reading/writing from/to your file
220	handles.	219	handles.
221		220
222	Example: wait for readability of STDIN, then read a line and disable the	221	Example: wait for readability of STDIN, then read a line and disable the
223	watcher.	222	watcher.
…		…
247		246
248	Although the callback might get passed parameters, their value and	247	Although the callback might get passed parameters, their value and
249	presence is undefined and you cannot rely on them. Portable AnyEvent	248	presence is undefined and you cannot rely on them. Portable AnyEvent
250	callbacks cannot use arguments passed to time watcher callbacks.	249	callbacks cannot use arguments passed to time watcher callbacks.
251		250
252	The callback will normally be invoked once only. If you specify another	251	The callback will normally be invoked only once. If you specify another
253	parameter, C<interval>, as a strictly positive number (> 0), then the	252	parameter, C<interval>, as a strictly positive number (> 0), then the
254	callback will be invoked regularly at that interval (in fractional	253	callback will be invoked regularly at that interval (in fractional
255	seconds) after the first invocation. If C<interval> is specified with a	254	seconds) after the first invocation. If C<interval> is specified with a
256	false value, then it is treated as if it were missing.	255	false value, then it is treated as if it were not specified at all.
257		256
258	The callback will be rescheduled before invoking the callback, but no	257	The callback will be rescheduled before invoking the callback, but no
259	attempt is done to avoid timer drift in most backends, so the interval is	258	attempt is made to avoid timer drift in most backends, so the interval is
260	only approximate.	259	only approximate.
261		260
262	Example: fire an event after 7.7 seconds.	261	Example: fire an event after 7.7 seconds.
263		262
264	my $w = AnyEvent->timer (after => 7.7, cb => sub {	263	my $w = AnyEvent->timer (after => 7.7, cb => sub {
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282		281
283	While most event loops expect timers to specified in a relative way, they	282	While most event loops expect timers to specified in a relative way, they
284	use absolute time internally. This makes a difference when your clock	283	use absolute time internally. This makes a difference when your clock
285	"jumps", for example, when ntp decides to set your clock backwards from	284	"jumps", for example, when ntp decides to set your clock backwards from
286	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to	285	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
287	fire "after" a second might actually take six years to finally fire.	286	fire "after a second" might actually take six years to finally fire.
288		287
289	AnyEvent cannot compensate for this. The only event loop that is conscious	288	AnyEvent cannot compensate for this. The only event loop that is conscious
290	about these issues is L<EV>, which offers both relative (ev_timer, based	289	of these issues is L<EV>, which offers both relative (ev_timer, based
291	on true relative time) and absolute (ev_periodic, based on wallclock time)	290	on true relative time) and absolute (ev_periodic, based on wallclock time)
292	timers.	291	timers.
293		292
294	AnyEvent always prefers relative timers, if available, matching the	293	AnyEvent always prefers relative timers, if available, matching the
295	AnyEvent API.	294	AnyEvent API.
…		…
317	I<In almost all cases (in all cases if you don't care), this is the	316	I<In almost all cases (in all cases if you don't care), this is the
318	function to call when you want to know the current time.>	317	function to call when you want to know the current time.>
319		318
320	This function is also often faster then C<< AnyEvent->time >>, and	319	This function is also often faster then C<< AnyEvent->time >>, and
321	thus the preferred method if you want some timestamp (for example,	320	thus the preferred method if you want some timestamp (for example,
322	L<AnyEvent::Handle> uses this to update it's activity timeouts).	321	L<AnyEvent::Handle> uses this to update its activity timeouts).
323		322
324	The rest of this section is only of relevance if you try to be very exact	323	The rest of this section is only of relevance if you try to be very exact
325	with your timing, you can skip it without bad conscience.	324	with your timing; you can skip it without a bad conscience.
326		325
327	For a practical example of when these times differ, consider L<Event::Lib>	326	For a practical example of when these times differ, consider L<Event::Lib>
328	and L<EV> and the following set-up:	327	and L<EV> and the following set-up:
329		328
330	The event loop is running and has just invoked one of your callback at	329	The event loop is running and has just invoked one of your callbacks at
331	time=500 (assume no other callbacks delay processing). In your callback,	330	time=500 (assume no other callbacks delay processing). In your callback,
332	you wait a second by executing C<sleep 1> (blocking the process for a	331	you wait a second by executing C<sleep 1> (blocking the process for a
333	second) and then (at time=501) you create a relative timer that fires	332	second) and then (at time=501) you create a relative timer that fires
334	after three seconds.	333	after three seconds.
335		334
…		…
428	=head3 Signal Races, Delays and Workarounds	427	=head3 Signal Races, Delays and Workarounds
429		428
430	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching	429	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
431	callbacks to signals in a generic way, which is a pity, as you cannot	430	callbacks to signals in a generic way, which is a pity, as you cannot
432	do race-free signal handling in perl, requiring C libraries for	431	do race-free signal handling in perl, requiring C libraries for
433	this. AnyEvent will try to do it's best, which means in some cases,	432	this. AnyEvent will try to do its best, which means in some cases,
434	signals will be delayed. The maximum time a signal might be delayed is	433	signals will be delayed. The maximum time a signal might be delayed is
435	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This	434	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
436	variable can be changed only before the first signal watcher is created,	435	variable can be changed only before the first signal watcher is created,
437	and should be left alone otherwise. This variable determines how often	436	and should be left alone otherwise. This variable determines how often
438	AnyEvent polls for signals (in case a wake-up was missed). Higher values	437	AnyEvent polls for signals (in case a wake-up was missed). Higher values
…		…
440	saving.	439	saving.
441		440
442	All these problems can be avoided by installing the optional	441	All these problems can be avoided by installing the optional
443	L<Async::Interrupt> module, which works with most event loops. It will not	442	L<Async::Interrupt> module, which works with most event loops. It will not
444	work with inherently broken event loops such as L<Event> or L<Event::Lib>	443	work with inherently broken event loops such as L<Event> or L<Event::Lib>
445	(and not with L<POE> currently, as POE does it's own workaround with	444	(and not with L<POE> currently, as POE does its own workaround with
446	one-second latency). For those, you just have to suffer the delays.	445	one-second latency). For those, you just have to suffer the delays.
447		446
448	=head2 CHILD PROCESS WATCHERS	447	=head2 CHILD PROCESS WATCHERS
449		448
450	$w = AnyEvent->child (pid => <process id>, cb => <callback>);	449	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
451		450
452	You can also watch on a child process exit and catch its exit status.	451	You can also watch for a child process exit and catch its exit status.
453		452
454	The child process is specified by the C<pid> argument (one some backends,	453	The child process is specified by the C<pid> argument (on some backends,
455	using C<0> watches for any child process exit, on others this will	454	using C<0> watches for any child process exit, on others this will
456	croak). The watcher will be triggered only when the child process has	455	croak). The watcher will be triggered only when the child process has
457	finished and an exit status is available, not on any trace events	456	finished and an exit status is available, not on any trace events
458	(stopped/continued).	457	(stopped/continued).
459		458
…		…
506		505
507	=head2 IDLE WATCHERS	506	=head2 IDLE WATCHERS
508		507
509	$w = AnyEvent->idle (cb => <callback>);	508	$w = AnyEvent->idle (cb => <callback>);
510		509
511	Repeatedly invoke the callback after the process becomes idle, until	510	This will repeatedly invoke the callback after the process becomes idle,
512	either the watcher is destroyed or new events have been detected.	511	until either the watcher is destroyed or new events have been detected.
513		512
514	Idle watchers are useful when there is a need to do something, but it	513	Idle watchers are useful when there is a need to do something, but it
515	is not so important (or wise) to do it instantly. The callback will be	514	is not so important (or wise) to do it instantly. The callback will be
516	invoked only when there is "nothing better to do", which is usually	515	invoked only when there is "nothing better to do", which is usually
517	defined as "all outstanding events have been handled and no new events	516	defined as "all outstanding events have been handled and no new events
…		…
556	will actively watch for new events and call your callbacks.	555	will actively watch for new events and call your callbacks.
557		556
558	AnyEvent is slightly different: it expects somebody else to run the event	557	AnyEvent is slightly different: it expects somebody else to run the event
559	loop and will only block when necessary (usually when told by the user).	558	loop and will only block when necessary (usually when told by the user).
560		559
561	The instrument to do that is called a "condition variable", so called	560	The tool to do that is called a "condition variable", so called because
562	because they represent a condition that must become true.	561	they represent a condition that must become true.
563		562
564	Now is probably a good time to look at the examples further below.	563	Now is probably a good time to look at the examples further below.
565		564
566	Condition variables can be created by calling the C<< AnyEvent->condvar	565	Condition variables can be created by calling the C<< AnyEvent->condvar
567	>> method, usually without arguments. The only argument pair allowed is	566	>> method, usually without arguments. The only argument pair allowed is
…		…
572	After creation, the condition variable is "false" until it becomes "true"	571	After creation, the condition variable is "false" until it becomes "true"
573	by calling the C<send> method (or calling the condition variable as if it	572	by calling the C<send> method (or calling the condition variable as if it
574	were a callback, read about the caveats in the description for the C<<	573	were a callback, read about the caveats in the description for the C<<
575	->send >> method).	574	->send >> method).
576		575
577	Condition variables are similar to callbacks, except that you can	576	Since condition variables are the most complex part of the AnyEvent API, here are
578	optionally wait for them. They can also be called merge points - points	577	some different mental models of what they are - pick the ones you can connect to:
579	in time where multiple outstanding events have been processed. And yet	578
580	another way to call them is transactions - each condition variable can be	579	=over 4
581	used to represent a transaction, which finishes at some point and delivers	580
582	a result. And yet some people know them as "futures" - a promise to	581	=item * Condition variables are like callbacks - you can call them (and pass them instead
583	compute/deliver something that you can wait for.	582	of callbacks). Unlike callbacks however, you can also wait for them to be called.
		583
		584	=item * Condition variables are signals - one side can emit or send them,
		585	the other side can wait for them, or install a handler that is called when
		586	the signal fires.
		587
		588	=item * Condition variables are like "Merge Points" - points in your program
		589	where you merge multiple independent results/control flows into one.
		590
		591	=item * Condition variables represent a transaction - functions that start
		592	some kind of transaction can return them, leaving the caller the choice
		593	between waiting in a blocking fashion, or setting a callback.
		594
		595	=item * Condition variables represent future values, or promises to deliver
		596	some result, long before the result is available.
		597
		598	=back
584		599
585	Condition variables are very useful to signal that something has finished,	600	Condition variables are very useful to signal that something has finished,
586	for example, if you write a module that does asynchronous http requests,	601	for example, if you write a module that does asynchronous http requests,
587	then a condition variable would be the ideal candidate to signal the	602	then a condition variable would be the ideal candidate to signal the
588	availability of results. The user can either act when the callback is	603	availability of results. The user can either act when the callback is
…		…
601		616
602	Condition variables are represented by hash refs in perl, and the keys	617	Condition variables are represented by hash refs in perl, and the keys
603	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing	618	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
604	easy (it is often useful to build your own transaction class on top of	619	easy (it is often useful to build your own transaction class on top of
605	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	620	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
606	it's C<new> method in your own C<new> method.	621	its C<new> method in your own C<new> method.
607		622
608	There are two "sides" to a condition variable - the "producer side" which	623	There are two "sides" to a condition variable - the "producer side" which
609	eventually calls C<< -> send >>, and the "consumer side", which waits	624	eventually calls C<< -> send >>, and the "consumer side", which waits
610	for the send to occur.	625	for the send to occur.
611		626
…		…
676	they were a code reference). Calling them directly is the same as calling	691	they were a code reference). Calling them directly is the same as calling
677	C<send>.	692	C<send>.
678		693
679	=item $cv->croak ($error)	694	=item $cv->croak ($error)
680		695
681	Similar to send, but causes all call's to C<< ->recv >> to invoke	696	Similar to send, but causes all calls to C<< ->recv >> to invoke
682	C<Carp::croak> with the given error message/object/scalar.	697	C<Carp::croak> with the given error message/object/scalar.
683		698
684	This can be used to signal any errors to the condition variable	699	This can be used to signal any errors to the condition variable
685	user/consumer. Doing it this way instead of calling C<croak> directly	700	user/consumer. Doing it this way instead of calling C<croak> directly
686	delays the error detetcion, but has the overwhelmign advantage that it	701	delays the error detection, but has the overwhelming advantage that it
687	diagnoses the error at the place where the result is expected, and not	702	diagnoses the error at the place where the result is expected, and not
688	deep in some event clalback without connection to the actual code causing	703	deep in some event callback with no connection to the actual code causing
689	the problem.	704	the problem.
690		705
691	=item $cv->begin ([group callback])	706	=item $cv->begin ([group callback])
692		707
693	=item $cv->end	708	=item $cv->end
…		…
731	one call to C<begin>, so the condvar waits for all calls to C<end> before	746	one call to C<begin>, so the condvar waits for all calls to C<end> before
732	sending.	747	sending.
733		748
734	The ping example mentioned above is slightly more complicated, as the	749	The ping example mentioned above is slightly more complicated, as the
735	there are results to be passwd back, and the number of tasks that are	750	there are results to be passwd back, and the number of tasks that are
736	begung can potentially be zero:	751	begun can potentially be zero:
737		752
738	my $cv = AnyEvent->condvar;	753	my $cv = AnyEvent->condvar;
739		754
740	my %result;	755	my %result;
741	$cv->begin (sub { shift->send (\%result) });	756	$cv->begin (sub { shift->send (\%result) });
…		…
762	to be called once the counter reaches C<0>, and second, it ensures that	777	to be called once the counter reaches C<0>, and second, it ensures that
763	C<send> is called even when C<no> hosts are being pinged (the loop	778	C<send> is called even when C<no> hosts are being pinged (the loop
764	doesn't execute once).	779	doesn't execute once).
765		780
766	This is the general pattern when you "fan out" into multiple (but	781	This is the general pattern when you "fan out" into multiple (but
767	potentially none) subrequests: use an outer C<begin>/C<end> pair to set	782	potentially zero) subrequests: use an outer C<begin>/C<end> pair to set
768	the callback and ensure C<end> is called at least once, and then, for each	783	the callback and ensure C<end> is called at least once, and then, for each
769	subrequest you start, call C<begin> and for each subrequest you finish,	784	subrequest you start, call C<begin> and for each subrequest you finish,
770	call C<end>.	785	call C<end>.
771		786
772	=back	787	=back
…		…
779	=over 4	794	=over 4
780		795
781	=item $cv->recv	796	=item $cv->recv
782		797
783	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak	798	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
784	>> methods have been called on c<$cv>, while servicing other watchers	799	>> methods have been called on C<$cv>, while servicing other watchers
785	normally.	800	normally.
786		801
787	You can only wait once on a condition - additional calls are valid but	802	You can only wait once on a condition - additional calls are valid but
788	will return immediately.	803	will return immediately.
789		804
…		…
806	caller decide whether the call will block or not (for example, by coupling	821	caller decide whether the call will block or not (for example, by coupling
807	condition variables with some kind of request results and supporting	822	condition variables with some kind of request results and supporting
808	callbacks so the caller knows that getting the result will not block,	823	callbacks so the caller knows that getting the result will not block,
809	while still supporting blocking waits if the caller so desires).	824	while still supporting blocking waits if the caller so desires).
810		825
811	You can ensure that C<< -recv >> never blocks by setting a callback and	826	You can ensure that C<< ->recv >> never blocks by setting a callback and
812	only calling C<< ->recv >> from within that callback (or at a later	827	only calling C<< ->recv >> from within that callback (or at a later
813	time). This will work even when the event loop does not support blocking	828	time). This will work even when the event loop does not support blocking
814	waits otherwise.	829	waits otherwise.
815		830
816	=item $bool = $cv->ready	831	=item $bool = $cv->ready
…		…
821	=item $cb = $cv->cb ($cb->($cv))	836	=item $cb = $cv->cb ($cb->($cv))
822		837
823	This is a mutator function that returns the callback set and optionally	838	This is a mutator function that returns the callback set and optionally
824	replaces it before doing so.	839	replaces it before doing so.
825		840
826	The callback will be called when the condition becomes (or already was)	841	The callback will be called when the condition becomes "true", i.e. when
827	"true", i.e. when C<send> or C<croak> are called (or were called), with	842	C<send> or C<croak> are called, with the only argument being the
828	the only argument being the condition variable itself. Calling C<recv>	843	condition variable itself. If the condition is already true, the
		844	callback is called immediately when it is set. Calling C<recv> inside
829	inside the callback or at any later time is guaranteed not to block.	845	the callback or at any later time is guaranteed not to block.
830		846
831	=back	847	=back
832		848
833	=head1 SUPPORTED EVENT LOOPS/BACKENDS	849	=head1 SUPPORTED EVENT LOOPS/BACKENDS
834		850
…		…
846	AnyEvent::Impl::EV based on EV (interface to libev, best choice).	862	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
847	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	863	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
848		864
849	=item Backends that are transparently being picked up when they are used.	865	=item Backends that are transparently being picked up when they are used.
850		866
851	These will be used when they are currently loaded when the first watcher	867	These will be used if they are already loaded when the first watcher
852	is created, in which case it is assumed that the application is using	868	is created, in which case it is assumed that the application is using
853	them. This means that AnyEvent will automatically pick the right backend	869	them. This means that AnyEvent will automatically pick the right backend
854	when the main program loads an event module before anything starts to	870	when the main program loads an event module before anything starts to
855	create watchers. Nothing special needs to be done by the main program.	871	create watchers. Nothing special needs to be done by the main program.
856		872
…		…
872		888
873	Support for IO::Async can only be partial, as it is too broken and	889	Support for IO::Async can only be partial, as it is too broken and
874	architecturally limited to even support the AnyEvent API. It also	890	architecturally limited to even support the AnyEvent API. It also
875	is the only event loop that needs the loop to be set explicitly, so	891	is the only event loop that needs the loop to be set explicitly, so
876	it can only be used by a main program knowing about AnyEvent. See	892	it can only be used by a main program knowing about AnyEvent. See
877	L<AnyEvent::Impl::Async> for the gory details.	893	L<AnyEvent::Impl::IOAsync> for the gory details.
878		894
879	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.	895	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
880		896
881	=item Event loops that are indirectly supported via other backends.	897	=item Event loops that are indirectly supported via other backends.
882		898
…		…
910	Contains C<undef> until the first watcher is being created, before the	926	Contains C<undef> until the first watcher is being created, before the
911	backend has been autodetected.	927	backend has been autodetected.
912		928
913	Afterwards it contains the event model that is being used, which is the	929	Afterwards it contains the event model that is being used, which is the
914	name of the Perl class implementing the model. This class is usually one	930	name of the Perl class implementing the model. This class is usually one
915	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the	931	of the C<AnyEvent::Impl::xxx> modules, but can be any other class in the
916	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it	932	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
917	will be C<urxvt::anyevent>).	933	will be C<urxvt::anyevent>).
918		934
919	=item AnyEvent::detect	935	=item AnyEvent::detect
920		936
921	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	937	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
922	if necessary. You should only call this function right before you would	938	if necessary. You should only call this function right before you would
923	have created an AnyEvent watcher anyway, that is, as late as possible at	939	have created an AnyEvent watcher anyway, that is, as late as possible at
924	runtime, and not e.g. while initialising of your module.	940	runtime, and not e.g. during initialisation of your module.
925		941
926	If you need to do some initialisation before AnyEvent watchers are	942	If you need to do some initialisation before AnyEvent watchers are
927	created, use C<post_detect>.	943	created, use C<post_detect>.
928		944
929	=item $guard = AnyEvent::post_detect { BLOCK }	945	=item $guard = AnyEvent::post_detect { BLOCK }
930		946
931	Arranges for the code block to be executed as soon as the event model is	947	Arranges for the code block to be executed as soon as the event model is
932	autodetected (or immediately if this has already happened).	948	autodetected (or immediately if that has already happened).
933		949
934	The block will be executed I<after> the actual backend has been detected	950	The block will be executed I<after> the actual backend has been detected
935	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been	951	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
936	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do	952	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
937	other initialisations - see the sources of L<AnyEvent::Strict> or	953	other initialisations - see the sources of L<AnyEvent::Strict> or
…		…
946	that automatically removes the callback again when it is destroyed (or	962	that automatically removes the callback again when it is destroyed (or
947	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for	963	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
948	a case where this is useful.	964	a case where this is useful.
949		965
950	Example: Create a watcher for the IO::AIO module and store it in	966	Example: Create a watcher for the IO::AIO module and store it in
951	C<$WATCHER>. Only do so after the event loop is initialised, though.	967	C<$WATCHER>, but do so only do so after the event loop is initialised.
952		968
953	our WATCHER;	969	our WATCHER;
954		970
955	my $guard = AnyEvent::post_detect {	971	my $guard = AnyEvent::post_detect {
956	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);	972	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
…		…
964	$WATCHER \|\|= $guard;	980	$WATCHER \|\|= $guard;
965		981
966	=item @AnyEvent::post_detect	982	=item @AnyEvent::post_detect
967		983
968	If there are any code references in this array (you can C<push> to it	984	If there are any code references in this array (you can C<push> to it
969	before or after loading AnyEvent), then they will called directly after	985	before or after loading AnyEvent), then they will be called directly
970	the event loop has been chosen.	986	after the event loop has been chosen.
971		987
972	You should check C<$AnyEvent::MODEL> before adding to this array, though:	988	You should check C<$AnyEvent::MODEL> before adding to this array, though:
973	if it is defined then the event loop has already been detected, and the	989	if it is defined then the event loop has already been detected, and the
974	array will be ignored.	990	array will be ignored.
975		991
…		…
1011	because it will stall the whole program, and the whole point of using	1027	because it will stall the whole program, and the whole point of using
1012	events is to stay interactive.	1028	events is to stay interactive.
1013		1029
1014	It is fine, however, to call C<< ->recv >> when the user of your module	1030	It is fine, however, to call C<< ->recv >> when the user of your module
1015	requests it (i.e. if you create a http request object ad have a method	1031	requests it (i.e. if you create a http request object ad have a method
1016	called C<results> that returns the results, it should call C<< ->recv >>	1032	called C<results> that returns the results, it may call C<< ->recv >>
1017	freely, as the user of your module knows what she is doing. always).	1033	freely, as the user of your module knows what she is doing. Always).
1018		1034
1019	=head1 WHAT TO DO IN THE MAIN PROGRAM	1035	=head1 WHAT TO DO IN THE MAIN PROGRAM
1020		1036
1021	There will always be a single main program - the only place that should	1037	There will always be a single main program - the only place that should
1022	dictate which event model to use.	1038	dictate which event model to use.
1023		1039
1024	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	1040	If the program is not event-based, it need not do anything special, even
1025	do anything special (it does not need to be event-based) and let AnyEvent	1041	when it depends on a module that uses an AnyEvent. If the program itself
1026	decide which implementation to chose if some module relies on it.	1042	uses AnyEvent, but does not care which event loop is used, all it needs
		1043	to do is C<use AnyEvent>. In either case, AnyEvent will choose the best
		1044	available loop implementation.
1027		1045
1028	If the main program relies on a specific event model - for example, in	1046	If the main program relies on a specific event model - for example, in
1029	Gtk2 programs you have to rely on the Glib module - you should load the	1047	Gtk2 programs you have to rely on the Glib module - you should load the
1030	event module before loading AnyEvent or any module that uses it: generally	1048	event module before loading AnyEvent or any module that uses it: generally
1031	speaking, you should load it as early as possible. The reason is that	1049	speaking, you should load it as early as possible. The reason is that
1032	modules might create watchers when they are loaded, and AnyEvent will	1050	modules might create watchers when they are loaded, and AnyEvent will
1033	decide on the event model to use as soon as it creates watchers, and it	1051	decide on the event model to use as soon as it creates watchers, and it
1034	might chose the wrong one unless you load the correct one yourself.	1052	might choose the wrong one unless you load the correct one yourself.
1035		1053
1036	You can chose to use a pure-perl implementation by loading the	1054	You can chose to use a pure-perl implementation by loading the
1037	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour	1055	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
1038	everywhere, but letting AnyEvent chose the model is generally better.	1056	everywhere, but letting AnyEvent chose the model is generally better.
1039		1057
…		…
1057	=head1 OTHER MODULES	1075	=head1 OTHER MODULES
1058		1076
1059	The following is a non-exhaustive list of additional modules that use	1077	The following is a non-exhaustive list of additional modules that use
1060	AnyEvent as a client and can therefore be mixed easily with other AnyEvent	1078	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
1061	modules and other event loops in the same program. Some of the modules	1079	modules and other event loops in the same program. Some of the modules
1062	come with AnyEvent, most are available via CPAN.	1080	come as part of AnyEvent, the others are available via CPAN.
1063		1081
1064	=over 4	1082	=over 4
1065		1083
1066	=item L<AnyEvent::Util>	1084	=item L<AnyEvent::Util>
1067		1085
1068	Contains various utility functions that replace often-used but blocking	1086	Contains various utility functions that replace often-used blocking
1069	functions such as C<inet_aton> by event-/callback-based versions.	1087	functions such as C<inet_aton> with event/callback-based versions.
1070		1088
1071	=item L<AnyEvent::Socket>	1089	=item L<AnyEvent::Socket>
1072		1090
1073	Provides various utility functions for (internet protocol) sockets,	1091	Provides various utility functions for (internet protocol) sockets,
1074	addresses and name resolution. Also functions to create non-blocking tcp	1092	addresses and name resolution. Also functions to create non-blocking tcp
…		…
1076		1094
1077	=item L<AnyEvent::Handle>	1095	=item L<AnyEvent::Handle>
1078		1096
1079	Provide read and write buffers, manages watchers for reads and writes,	1097	Provide read and write buffers, manages watchers for reads and writes,
1080	supports raw and formatted I/O, I/O queued and fully transparent and	1098	supports raw and formatted I/O, I/O queued and fully transparent and
1081	non-blocking SSL/TLS (via L<AnyEvent::TLS>.	1099	non-blocking SSL/TLS (via L<AnyEvent::TLS>).
1082		1100
1083	=item L<AnyEvent::DNS>	1101	=item L<AnyEvent::DNS>
1084		1102
1085	Provides rich asynchronous DNS resolver capabilities.	1103	Provides rich asynchronous DNS resolver capabilities.
1086		1104
		1105	=item L<AnyEvent::HTTP>, L<AnyEvent::IRC>, L<AnyEvent::XMPP>, L<AnyEvent::GPSD>, L<AnyEvent::IGS>, L<AnyEvent::FCP>
		1106
		1107	Implement event-based interfaces to the protocols of the same name (for
		1108	the curious, IGS is the International Go Server and FCP is the Freenet
		1109	Client Protocol).
		1110
		1111	=item L<AnyEvent::Handle::UDP>
		1112
		1113	Here be danger!
		1114
		1115	As Pauli would put it, "Not only is it not right, it's not even wrong!" -
		1116	there are so many things wrong with AnyEvent::Handle::UDP, most notably
		1117	its use of a stream-based API with a protocol that isn't streamable, that
		1118	the only way to improve it is to delete it.
		1119
		1120	It features data corruption (but typically only under load) and general
		1121	confusion. On top, the author is not only clueless about UDP but also
		1122	fact-resistant - some gems of his understanding: "connect doesn't work
		1123	with UDP", "UDP packets are not IP packets", "UDP only has datagrams, not
		1124	packets", "I don't need to implement proper error checking as UDP doesn't
		1125	support error checking" and so on - he doesn't even understand what's
		1126	wrong with his module when it is explained to him.
		1127
1087	=item L<AnyEvent::HTTP>	1128	=item L<AnyEvent::DBI>
1088		1129
1089	A simple-to-use HTTP library that is capable of making a lot of concurrent	1130	Executes L<DBI> requests asynchronously in a proxy process for you,
1090	HTTP requests.	1131	notifying you in an event-based way when the operation is finished.
		1132
		1133	=item L<AnyEvent::AIO>
		1134
		1135	Truly asynchronous (as opposed to non-blocking) I/O, should be in the
		1136	toolbox of every event programmer. AnyEvent::AIO transparently fuses
		1137	L<IO::AIO> and AnyEvent together, giving AnyEvent access to event-based
		1138	file I/O, and much more.
1091		1139
1092	=item L<AnyEvent::HTTPD>	1140	=item L<AnyEvent::HTTPD>
1093		1141
1094	Provides a simple web application server framework.	1142	A simple embedded webserver.
1095		1143
1096	=item L<AnyEvent::FastPing>	1144	=item L<AnyEvent::FastPing>
1097		1145
1098	The fastest ping in the west.	1146	The fastest ping in the west.
1099
1100	=item L<AnyEvent::DBI>
1101
1102	Executes L<DBI> requests asynchronously in a proxy process.
1103
1104	=item L<AnyEvent::AIO>
1105
1106	Truly asynchronous I/O, should be in the toolbox of every event
1107	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
1108	together.
1109
1110	=item L<AnyEvent::BDB>
1111
1112	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
1113	L<BDB> and AnyEvent together.
1114
1115	=item L<AnyEvent::GPSD>
1116
1117	A non-blocking interface to gpsd, a daemon delivering GPS information.
1118
1119	=item L<AnyEvent::IRC>
1120
1121	AnyEvent based IRC client module family (replacing the older Net::IRC3).
1122
1123	=item L<AnyEvent::XMPP>
1124
1125	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
1126	Net::XMPP2>.
1127
1128	=item L<AnyEvent::IGS>
1129
1130	A non-blocking interface to the Internet Go Server protocol (used by
1131	L<App::IGS>).
1132
1133	=item L<Net::FCP>
1134
1135	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
1136	of AnyEvent.
1137
1138	=item L<Event::ExecFlow>
1139
1140	High level API for event-based execution flow control.
1141		1147
1142	=item L<Coro>	1148	=item L<Coro>
1143		1149
1144	Has special support for AnyEvent via L<Coro::AnyEvent>.	1150	Has special support for AnyEvent via L<Coro::AnyEvent>.
1145		1151
…		…
1159		1165
1160	BEGIN { AnyEvent::common_sense }	1166	BEGIN { AnyEvent::common_sense }
1161		1167
1162	use Carp ();	1168	use Carp ();
1163		1169
1164	our $VERSION = '5.26';	1170	our $VERSION = '5.271';
1165	our $MODEL;	1171	our $MODEL;
1166		1172
1167	our $AUTOLOAD;	1173	our $AUTOLOAD;
1168	our @ISA;	1174	our @ISA;
1169		1175
…		…
1849	check the arguments passed to most method calls. If it finds any problems,	1855	check the arguments passed to most method calls. If it finds any problems,
1850	it will croak.	1856	it will croak.
1851		1857
1852	In other words, enables "strict" mode.	1858	In other words, enables "strict" mode.
1853		1859
1854	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>	1860	Unlike C<use strict> (or its modern cousin, C<< use L<common::sense>
1855	>>, it is definitely recommended to keep it off in production. Keeping	1861	>>, it is definitely recommended to keep it off in production. Keeping
1856	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs	1862	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
1857	can be very useful, however.	1863	can be very useful, however.
1858		1864
1859	=item C<PERL_ANYEVENT_MODEL>	1865	=item C<PERL_ANYEVENT_MODEL>
…		…
2505	unless defined $SIG{PIPE};	2511	unless defined $SIG{PIPE};
2506		2512
2507	=head1 RECOMMENDED/OPTIONAL MODULES	2513	=head1 RECOMMENDED/OPTIONAL MODULES
2508		2514
2509	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and	2515	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
2510	it's built-in modules) are required to use it.	2516	its built-in modules) are required to use it.
2511		2517
2512	That does not mean that AnyEvent won't take advantage of some additional	2518	That does not mean that AnyEvent won't take advantage of some additional
2513	modules if they are installed.	2519	modules if they are installed.
2514		2520
2515	This section explains which additional modules will be used, and how they	2521	This section explains which additional modules will be used, and how they
…		…
2573	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.	2579	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
2574		2580
2575	=item L<Time::HiRes>	2581	=item L<Time::HiRes>
2576		2582
2577	This module is part of perl since release 5.008. It will be used when the	2583	This module is part of perl since release 5.008. It will be used when the
2578	chosen event library does not come with a timing source on it's own. The	2584	chosen event library does not come with a timing source of its own. The
2579	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to	2585	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
2580	try to use a monotonic clock for timing stability.	2586	try to use a monotonic clock for timing stability.
2581		2587
2582	=back	2588	=back
2583		2589

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.320 by root, Mon Apr 12 02:50:31 2010 UTC vs. Revision 1.331 by root, Tue Aug 31 01:00:48 2010 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.320 by root, Mon Apr 12 02:50:31 2010 UTC vs.
Revision 1.331 by root, Tue Aug 31 01:00:48 2010 UTC