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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.94 by root, Sat Apr 26 04:33:51 2008 UTC vs.
Revision 1.143 by root, Wed May 28 23:57:38 2008 UTC

…		…
1	=head1 NAME	1	=head1 => NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
16	...	16	...
17	});	17	});
18		18
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	19	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		20	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	21	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's
22		22
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		24
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	26	nowadays. So what is different about AnyEvent?
…		…
48	isn't itself. What's worse, all the potential users of your module are	48	isn't itself. What's worse, all the potential users of your module are
49	I<also> forced to use the same event loop you use.	49	I<also> forced to use the same event loop you use.
50		50
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	53	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	54	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	55	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	56	event models it supports (including stuff like POE and IO::Async, as long
57	as those use one of the supported event loops. It is trivial to add new	57	as those use one of the supported event loops. It is trivial to add new
58	event loops to AnyEvent, too, so it is future-proof).	58	event loops to AnyEvent, too, so it is future-proof).
59		59
60	In addition to being free of having to use I<the one and only true event	60	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	61	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enourmous amount of code and strict rules you have to	62	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	63	follow. AnyEvent, on the other hand, is lean and up to the point, by only
64	offering the functionality that is necessary, in as thin as a wrapper as	64	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	65	technically possible.
66		66
		67	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		68	of useful functionality, such as an asynchronous DNS resolver, 100%
		69	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		70	such as Windows) and lots of real-world knowledge and workarounds for
		71	platform bugs and differences.
		72
67	Of course, if you want lots of policy (this can arguably be somewhat	73	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	74	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	75	model, you should I<not> use this module.
70
71		76
72	=head1 DESCRIPTION	77	=head1 DESCRIPTION
73		78
74	L<AnyEvent> provides an identical interface to multiple event loops. This	79	L<AnyEvent> provides an identical interface to multiple event loops. This
75	allows module authors to utilise an event loop without forcing module	80	allows module authors to utilise an event loop without forcing module
…		…
79	The interface itself is vaguely similar, but not identical to the L<Event>	84	The interface itself is vaguely similar, but not identical to the L<Event>
80	module.	85	module.
81		86
82	During the first call of any watcher-creation method, the module tries	87	During the first call of any watcher-creation method, the module tries
83	to detect the currently loaded event loop by probing whether one of the	88	to detect the currently loaded event loop by probing whether one of the
84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	89	following modules is already loaded: L<EV>,
85	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	90	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
86	L<POE>. The first one found is used. If none are found, the module tries	91	L<POE>. The first one found is used. If none are found, the module tries
87	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	92	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
88	adaptor should always succeed) in the order given. The first one that can	93	adaptor should always succeed) in the order given. The first one that can
89	be successfully loaded will be used. If, after this, still none could be	94	be successfully loaded will be used. If, after this, still none could be
…		…
103	starts using it, all bets are off. Maybe you should tell their authors to	108	starts using it, all bets are off. Maybe you should tell their authors to
104	use AnyEvent so their modules work together with others seamlessly...	109	use AnyEvent so their modules work together with others seamlessly...
105		110
106	The pure-perl implementation of AnyEvent is called	111	The pure-perl implementation of AnyEvent is called
107	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	112	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
108	explicitly.	113	explicitly and enjoy the high availability of that event loop :)
109		114
110	=head1 WATCHERS	115	=head1 WATCHERS
111		116
112	AnyEvent has the central concept of a I<watcher>, which is an object that	117	AnyEvent has the central concept of a I<watcher>, which is an object that
113	stores relevant data for each kind of event you are waiting for, such as	118	stores relevant data for each kind of event you are waiting for, such as
114	the callback to call, the filehandle to watch, etc.	119	the callback to call, the file handle to watch, etc.
115		120
116	These watchers are normal Perl objects with normal Perl lifetime. After	121	These watchers are normal Perl objects with normal Perl lifetime. After
117	creating a watcher it will immediately "watch" for events and invoke the	122	creating a watcher it will immediately "watch" for events and invoke the
118	callback when the event occurs (of course, only when the event model	123	callback when the event occurs (of course, only when the event model
119	is in control).	124	is in control).
…		…
228	timers.	233	timers.
229		234
230	AnyEvent always prefers relative timers, if available, matching the	235	AnyEvent always prefers relative timers, if available, matching the
231	AnyEvent API.	236	AnyEvent API.
232		237
		238	AnyEvent has two additional methods that return the "current time":
		239
		240	=over 4
		241
		242	=item AnyEvent->time
		243
		244	This returns the "current wallclock time" as a fractional number of
		245	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		246	return, and the result is guaranteed to be compatible with those).
		247
		248	It progresses independently of any event loop processing.
		249
		250	In almost all cases (in all cases if you don't care), this is the function
		251	to call when you want to know the current time.
		252
		253	=item AnyEvent->now
		254
		255	This also returns the "current wallclock time", but unlike C<time>, above,
		256	this value might change only once per event loop iteration, depending on
		257	the event loop (most return the same time as C<time>, above). This is the
		258	time that AnyEvent timers get scheduled against.
		259
		260	For a practical example of when these times differ, consider L<Event::Lib>
		261	and L<EV> and the following set-up:
		262
		263	The event loop is running and has just invoked one of your callback at
		264	time=500 (assume no other callbacks delay processing). In your callback,
		265	you wait a second by executing C<sleep 1> (blocking the process for a
		266	second) and then (at time=501) you create a relative timer that fires
		267	after three seconds.
		268
		269	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		270	both return C<501>, because that is the current time, and the timer will
		271	be scheduled to fire at time=504 (C<501> + C<3>).
		272
		273	With L<EV>m C<< AnyEvent->time >> returns C<501> (as that is the current
		274	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		275	last event processing phase started. With L<EV>, your timer gets scheduled
		276	to run at time=503 (C<500> + C<3>).
		277
		278	In one sense, L<Event::Lib> is more exact, as it uses the current time
		279	regardless of any delays introduced by event processing. However, most
		280	callbacks do not expect large delays in processing, so this causes a
		281	higher drift (and a lot more syscalls to get the current time).
		282
		283	In another sense, L<EV> is more exact, as your timer will be scheduled at
		284	the same time, regardless of how long event processing actually took.
		285
		286	In either case, if you care (and in most cases, you don't), then you
		287	can get whatever behaviour you want with any event loop, by taking the
		288	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		289	account.
		290
		291	=back
		292
233	=head2 SIGNAL WATCHERS	293	=head2 SIGNAL WATCHERS
234		294
235	You can watch for signals using a signal watcher, C<signal> is the signal	295	You can watch for signals using a signal watcher, C<signal> is the signal
236	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	296	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
237	be invoked whenever a signal occurs.	297	be invoked whenever a signal occurs.
238		298
239	Although the callback might get passed parameters, their value and	299	Although the callback might get passed parameters, their value and
240	presence is undefined and you cannot rely on them. Portable AnyEvent	300	presence is undefined and you cannot rely on them. Portable AnyEvent
241	callbacks cannot use arguments passed to signal watcher callbacks.	301	callbacks cannot use arguments passed to signal watcher callbacks.
242		302
243	Multiple signal occurances can be clumped together into one callback	303	Multiple signal occurrences can be clumped together into one callback
244	invocation, and callback invocation will be synchronous. synchronous means	304	invocation, and callback invocation will be synchronous. Synchronous means
245	that it might take a while until the signal gets handled by the process,	305	that it might take a while until the signal gets handled by the process,
246	but it is guarenteed not to interrupt any other callbacks.	306	but it is guaranteed not to interrupt any other callbacks.
247		307
248	The main advantage of using these watchers is that you can share a signal	308	The main advantage of using these watchers is that you can share a signal
249	between multiple watchers.	309	between multiple watchers.
250		310
251	This watcher might use C<%SIG>, so programs overwriting those signals	311	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
280		340
281	Example: fork a process and wait for it	341	Example: fork a process and wait for it
282		342
283	my $done = AnyEvent->condvar;	343	my $done = AnyEvent->condvar;
284		344
285	AnyEvent::detect; # force event module to be initialised
286
287	my $pid = fork or exit 5;	345	my $pid = fork or exit 5;
288		346
289	my $w = AnyEvent->child (	347	my $w = AnyEvent->child (
290	pid => $pid,	348	pid => $pid,
291	cb => sub {	349	cb => sub {
292	my ($pid, $status) = @_;	350	my ($pid, $status) = @_;
293	warn "pid $pid exited with status $status";	351	warn "pid $pid exited with status $status";
294	$done->broadcast;	352	$done->send;
295	},	353	},
296	);	354	);
297		355
298	# do something else, then wait for process exit	356	# do something else, then wait for process exit
299	$done->wait;	357	$done->recv;
300		358
301	=head2 CONDITION VARIABLES	359	=head2 CONDITION VARIABLES
302		360
		361	If you are familiar with some event loops you will know that all of them
		362	require you to run some blocking "loop", "run" or similar function that
		363	will actively watch for new events and call your callbacks.
		364
		365	AnyEvent is different, it expects somebody else to run the event loop and
		366	will only block when necessary (usually when told by the user).
		367
		368	The instrument to do that is called a "condition variable", so called
		369	because they represent a condition that must become true.
		370
303	Condition variables can be created by calling the C<< AnyEvent->condvar >>	371	Condition variables can be created by calling the C<< AnyEvent->condvar
304	method without any arguments.	372	>> method, usually without arguments. The only argument pair allowed is
		373	C<cb>, which specifies a callback to be called when the condition variable
		374	becomes true.
305		375
306	A condition variable waits for a condition - precisely that the C<<	376	After creation, the condition variable is "false" until it becomes "true"
307	->broadcast >> method has been called.	377	by calling the C<send> method (or calling the condition variable as if it
		378	were a callback, read about the caveats in the description for the C<<
		379	->send >> method).
308		380
309	They are very useful to signal that a condition has been fulfilled, for	381	Condition variables are similar to callbacks, except that you can
		382	optionally wait for them. They can also be called merge points - points
		383	in time where multiple outstanding events have been processed. And yet
		384	another way to call them is transactions - each condition variable can be
		385	used to represent a transaction, which finishes at some point and delivers
		386	a result.
		387
		388	Condition variables are very useful to signal that something has finished,
310	example, if you write a module that does asynchronous http requests,	389	for example, if you write a module that does asynchronous http requests,
311	then a condition variable would be the ideal candidate to signal the	390	then a condition variable would be the ideal candidate to signal the
312	availability of results.	391	availability of results. The user can either act when the callback is
		392	called or can synchronously C<< ->recv >> for the results.
313		393
314	You can also use condition variables to block your main program until	394	You can also use them to simulate traditional event loops - for example,
315	an event occurs - for example, you could C<< ->wait >> in your main	395	you can block your main program until an event occurs - for example, you
316	program until the user clicks the Quit button in your app, which would C<<	396	could C<< ->recv >> in your main program until the user clicks the Quit
317	->broadcast >> the "quit" event.	397	button of your app, which would C<< ->send >> the "quit" event.
318		398
319	Note that condition variables recurse into the event loop - if you have	399	Note that condition variables recurse into the event loop - if you have
320	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	400	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
321	lose. Therefore, condition variables are good to export to your caller, but	401	lose. Therefore, condition variables are good to export to your caller, but
322	you should avoid making a blocking wait yourself, at least in callbacks,	402	you should avoid making a blocking wait yourself, at least in callbacks,
323	as this asks for trouble.	403	as this asks for trouble.
324		404
325	This object has two methods:	405	Condition variables are represented by hash refs in perl, and the keys
		406	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		407	easy (it is often useful to build your own transaction class on top of
		408	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		409	it's C<new> method in your own C<new> method.
		410
		411	There are two "sides" to a condition variable - the "producer side" which
		412	eventually calls C<< -> send >>, and the "consumer side", which waits
		413	for the send to occur.
		414
		415	Example: wait for a timer.
		416
		417	# wait till the result is ready
		418	my $result_ready = AnyEvent->condvar;
		419
		420	# do something such as adding a timer
		421	# or socket watcher the calls $result_ready->send
		422	# when the "result" is ready.
		423	# in this case, we simply use a timer:
		424	my $w = AnyEvent->timer (
		425	after => 1,
		426	cb => sub { $result_ready->send },
		427	);
		428
		429	# this "blocks" (while handling events) till the callback
		430	# calls send
		431	$result_ready->recv;
		432
		433	Example: wait for a timer, but take advantage of the fact that
		434	condition variables are also code references.
		435
		436	my $done = AnyEvent->condvar;
		437	my $delay = AnyEvent->timer (after => 5, cb => $done);
		438	$done->recv;
		439
		440	=head3 METHODS FOR PRODUCERS
		441
		442	These methods should only be used by the producing side, i.e. the
		443	code/module that eventually sends the signal. Note that it is also
		444	the producer side which creates the condvar in most cases, but it isn't
		445	uncommon for the consumer to create it as well.
326		446
327	=over 4	447	=over 4
328		448
		449	=item $cv->send (...)
		450
		451	Flag the condition as ready - a running C<< ->recv >> and all further
		452	calls to C<recv> will (eventually) return after this method has been
		453	called. If nobody is waiting the send will be remembered.
		454
		455	If a callback has been set on the condition variable, it is called
		456	immediately from within send.
		457
		458	Any arguments passed to the C<send> call will be returned by all
		459	future C<< ->recv >> calls.
		460
		461	Condition variables are overloaded so one can call them directly
		462	(as a code reference). Calling them directly is the same as calling
		463	C<send>. Note, however, that many C-based event loops do not handle
		464	overloading, so as tempting as it may be, passing a condition variable
		465	instead of a callback does not work. Both the pure perl and EV loops
		466	support overloading, however, as well as all functions that use perl to
		467	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		468	example).
		469
		470	=item $cv->croak ($error)
		471
		472	Similar to send, but causes all call's to C<< ->recv >> to invoke
		473	C<Carp::croak> with the given error message/object/scalar.
		474
		475	This can be used to signal any errors to the condition variable
		476	user/consumer.
		477
		478	=item $cv->begin ([group callback])
		479
329	=item $cv->wait	480	=item $cv->end
330		481
331	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	482	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		483
		484	These two methods can be used to combine many transactions/events into
		485	one. For example, a function that pings many hosts in parallel might want
		486	to use a condition variable for the whole process.
		487
		488	Every call to C<< ->begin >> will increment a counter, and every call to
		489	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		490	>>, the (last) callback passed to C<begin> will be executed. That callback
		491	is I<supposed> to call C<< ->send >>, but that is not required. If no
		492	callback was set, C<send> will be called without any arguments.
		493
		494	Let's clarify this with the ping example:
		495
		496	my $cv = AnyEvent->condvar;
		497
		498	my %result;
		499	$cv->begin (sub { $cv->send (\%result) });
		500
		501	for my $host (@list_of_hosts) {
		502	$cv->begin;
		503	ping_host_then_call_callback $host, sub {
		504	$result{$host} = ...;
		505	$cv->end;
		506	};
		507	}
		508
		509	$cv->end;
		510
		511	This code fragment supposedly pings a number of hosts and calls
		512	C<send> after results for all then have have been gathered - in any
		513	order. To achieve this, the code issues a call to C<begin> when it starts
		514	each ping request and calls C<end> when it has received some result for
		515	it. Since C<begin> and C<end> only maintain a counter, the order in which
		516	results arrive is not relevant.
		517
		518	There is an additional bracketing call to C<begin> and C<end> outside the
		519	loop, which serves two important purposes: first, it sets the callback
		520	to be called once the counter reaches C<0>, and second, it ensures that
		521	C<send> is called even when C<no> hosts are being pinged (the loop
		522	doesn't execute once).
		523
		524	This is the general pattern when you "fan out" into multiple subrequests:
		525	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		526	is called at least once, and then, for each subrequest you start, call
		527	C<begin> and for each subrequest you finish, call C<end>.
		528
		529	=back
		530
		531	=head3 METHODS FOR CONSUMERS
		532
		533	These methods should only be used by the consuming side, i.e. the
		534	code awaits the condition.
		535
		536	=over 4
		537
		538	=item $cv->recv
		539
		540	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
332	called on c<$cv>, while servicing other watchers normally.	541	>> methods have been called on c<$cv>, while servicing other watchers
		542	normally.
333		543
334	You can only wait once on a condition - additional calls will return	544	You can only wait once on a condition - additional calls are valid but
335	immediately.	545	will return immediately.
		546
		547	If an error condition has been set by calling C<< ->croak >>, then this
		548	function will call C<croak>.
		549
		550	In list context, all parameters passed to C<send> will be returned,
		551	in scalar context only the first one will be returned.
336		552
337	Not all event models support a blocking wait - some die in that case	553	Not all event models support a blocking wait - some die in that case
338	(programs might want to do that to stay interactive), so I<if you are	554	(programs might want to do that to stay interactive), so I<if you are
339	using this from a module, never require a blocking wait>, but let the	555	using this from a module, never require a blocking wait>, but let the
340	caller decide whether the call will block or not (for example, by coupling	556	caller decide whether the call will block or not (for example, by coupling
341	condition variables with some kind of request results and supporting	557	condition variables with some kind of request results and supporting
342	callbacks so the caller knows that getting the result will not block,	558	callbacks so the caller knows that getting the result will not block,
343	while still suppporting blocking waits if the caller so desires).	559	while still supporting blocking waits if the caller so desires).
344		560
345	Another reason I<never> to C<< ->wait >> in a module is that you cannot	561	Another reason I<never> to C<< ->recv >> in a module is that you cannot
346	sensibly have two C<< ->wait >>'s in parallel, as that would require	562	sensibly have two C<< ->recv >>'s in parallel, as that would require
347	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	563	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
348	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	564	can supply.
349	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
350	from different coroutines, however).
351		565
352	=item $cv->broadcast	566	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		567	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		568	versions and also integrates coroutines into AnyEvent, making blocking
		569	C<< ->recv >> calls perfectly safe as long as they are done from another
		570	coroutine (one that doesn't run the event loop).
353		571
354	Flag the condition as ready - a running C<< ->wait >> and all further	572	You can ensure that C<< -recv >> never blocks by setting a callback and
355	calls to C<wait> will (eventually) return after this method has been	573	only calling C<< ->recv >> from within that callback (or at a later
356	called. If nobody is waiting the broadcast will be remembered..	574	time). This will work even when the event loop does not support blocking
		575	waits otherwise.
		576
		577	=item $bool = $cv->ready
		578
		579	Returns true when the condition is "true", i.e. whether C<send> or
		580	C<croak> have been called.
		581
		582	=item $cb = $cv->cb ([new callback])
		583
		584	This is a mutator function that returns the callback set and optionally
		585	replaces it before doing so.
		586
		587	The callback will be called when the condition becomes "true", i.e. when
		588	C<send> or C<croak> are called. Calling C<recv> inside the callback
		589	or at any later time is guaranteed not to block.
357		590
358	=back	591	=back
359
360	Example:
361
362	# wait till the result is ready
363	my $result_ready = AnyEvent->condvar;
364
365	# do something such as adding a timer
366	# or socket watcher the calls $result_ready->broadcast
367	# when the "result" is ready.
368	# in this case, we simply use a timer:
369	my $w = AnyEvent->timer (
370	after => 1,
371	cb => sub { $result_ready->broadcast },
372	);
373
374	# this "blocks" (while handling events) till the watcher
375	# calls broadcast
376	$result_ready->wait;
377		592
378	=head1 GLOBAL VARIABLES AND FUNCTIONS	593	=head1 GLOBAL VARIABLES AND FUNCTIONS
379		594
380	=over 4	595	=over 4
381		596
…		…
387	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	602	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
388	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	603	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
389		604
390	The known classes so far are:	605	The known classes so far are:
391		606
392	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
393	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
394	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	607	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
395	AnyEvent::Impl::Event based on Event, second best choice.	608	AnyEvent::Impl::Event based on Event, second best choice.
		609	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
396	AnyEvent::Impl::Glib based on Glib, third-best choice.	610	AnyEvent::Impl::Glib based on Glib, third-best choice.
397	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
398	AnyEvent::Impl::Tk based on Tk, very bad choice.	611	AnyEvent::Impl::Tk based on Tk, very bad choice.
399	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	612	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
400	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	613	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
401	AnyEvent::Impl::POE based on POE, not generic enough for full support.	614	AnyEvent::Impl::POE based on POE, not generic enough for full support.
402		615
…		…
415	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	628	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
416	if necessary. You should only call this function right before you would	629	if necessary. You should only call this function right before you would
417	have created an AnyEvent watcher anyway, that is, as late as possible at	630	have created an AnyEvent watcher anyway, that is, as late as possible at
418	runtime.	631	runtime.
419		632
		633	=item $guard = AnyEvent::post_detect { BLOCK }
		634
		635	Arranges for the code block to be executed as soon as the event model is
		636	autodetected (or immediately if this has already happened).
		637
		638	If called in scalar or list context, then it creates and returns an object
		639	that automatically removes the callback again when it is destroyed. See
		640	L<Coro::BDB> for a case where this is useful.
		641
		642	=item @AnyEvent::post_detect
		643
		644	If there are any code references in this array (you can C<push> to it
		645	before or after loading AnyEvent), then they will called directly after
		646	the event loop has been chosen.
		647
		648	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		649	if it contains a true value then the event loop has already been detected,
		650	and the array will be ignored.
		651
		652	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		653
420	=back	654	=back
421		655
422	=head1 WHAT TO DO IN A MODULE	656	=head1 WHAT TO DO IN A MODULE
423		657
424	As a module author, you should C<use AnyEvent> and call AnyEvent methods	658	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
427	Be careful when you create watchers in the module body - AnyEvent will	661	Be careful when you create watchers in the module body - AnyEvent will
428	decide which event module to use as soon as the first method is called, so	662	decide which event module to use as soon as the first method is called, so
429	by calling AnyEvent in your module body you force the user of your module	663	by calling AnyEvent in your module body you force the user of your module
430	to load the event module first.	664	to load the event module first.
431		665
432	Never call C<< ->wait >> on a condition variable unless you I<know> that	666	Never call C<< ->recv >> on a condition variable unless you I<know> that
433	the C<< ->broadcast >> method has been called on it already. This is	667	the C<< ->send >> method has been called on it already. This is
434	because it will stall the whole program, and the whole point of using	668	because it will stall the whole program, and the whole point of using
435	events is to stay interactive.	669	events is to stay interactive.
436		670
437	It is fine, however, to call C<< ->wait >> when the user of your module	671	It is fine, however, to call C<< ->recv >> when the user of your module
438	requests it (i.e. if you create a http request object ad have a method	672	requests it (i.e. if you create a http request object ad have a method
439	called C<results> that returns the results, it should call C<< ->wait >>	673	called C<results> that returns the results, it should call C<< ->recv >>
440	freely, as the user of your module knows what she is doing. always).	674	freely, as the user of your module knows what she is doing. always).
441		675
442	=head1 WHAT TO DO IN THE MAIN PROGRAM	676	=head1 WHAT TO DO IN THE MAIN PROGRAM
443		677
444	There will always be a single main program - the only place that should	678	There will always be a single main program - the only place that should
…		…
446		680
447	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	681	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
448	do anything special (it does not need to be event-based) and let AnyEvent	682	do anything special (it does not need to be event-based) and let AnyEvent
449	decide which implementation to chose if some module relies on it.	683	decide which implementation to chose if some module relies on it.
450		684
451	If the main program relies on a specific event model. For example, in	685	If the main program relies on a specific event model - for example, in
452	Gtk2 programs you have to rely on the Glib module. You should load the	686	Gtk2 programs you have to rely on the Glib module - you should load the
453	event module before loading AnyEvent or any module that uses it: generally	687	event module before loading AnyEvent or any module that uses it: generally
454	speaking, you should load it as early as possible. The reason is that	688	speaking, you should load it as early as possible. The reason is that
455	modules might create watchers when they are loaded, and AnyEvent will	689	modules might create watchers when they are loaded, and AnyEvent will
456	decide on the event model to use as soon as it creates watchers, and it	690	decide on the event model to use as soon as it creates watchers, and it
457	might chose the wrong one unless you load the correct one yourself.	691	might chose the wrong one unless you load the correct one yourself.
458		692
459	You can chose to use a rather inefficient pure-perl implementation by	693	You can chose to use a pure-perl implementation by loading the
460	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	694	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
461	behaviour everywhere, but letting AnyEvent chose is generally better.	695	everywhere, but letting AnyEvent chose the model is generally better.
		696
		697	=head2 MAINLOOP EMULATION
		698
		699	Sometimes (often for short test scripts, or even standalone programs who
		700	only want to use AnyEvent), you do not want to run a specific event loop.
		701
		702	In that case, you can use a condition variable like this:
		703
		704	AnyEvent->condvar->recv;
		705
		706	This has the effect of entering the event loop and looping forever.
		707
		708	Note that usually your program has some exit condition, in which case
		709	it is better to use the "traditional" approach of storing a condition
		710	variable somewhere, waiting for it, and sending it when the program should
		711	exit cleanly.
		712
		713
		714	=head1 OTHER MODULES
		715
		716	The following is a non-exhaustive list of additional modules that use
		717	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		718	in the same program. Some of the modules come with AnyEvent, some are
		719	available via CPAN.
		720
		721	=over 4
		722
		723	=item L<AnyEvent::Util>
		724
		725	Contains various utility functions that replace often-used but blocking
		726	functions such as C<inet_aton> by event-/callback-based versions.
		727
		728	=item L<AnyEvent::Handle>
		729
		730	Provide read and write buffers and manages watchers for reads and writes.
		731
		732	=item L<AnyEvent::Socket>
		733
		734	Provides various utility functions for (internet protocol) sockets,
		735	addresses and name resolution. Also functions to create non-blocking tcp
		736	connections or tcp servers, with IPv6 and SRV record support and more.
		737
		738	=item L<AnyEvent::DNS>
		739
		740	Provides rich asynchronous DNS resolver capabilities.
		741
		742	=item L<AnyEvent::HTTPD>
		743
		744	Provides a simple web application server framework.
		745
		746	=item L<AnyEvent::FastPing>
		747
		748	The fastest ping in the west.
		749
		750	=item L<Net::IRC3>
		751
		752	AnyEvent based IRC client module family.
		753
		754	=item L<Net::XMPP2>
		755
		756	AnyEvent based XMPP (Jabber protocol) module family.
		757
		758	=item L<Net::FCP>
		759
		760	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		761	of AnyEvent.
		762
		763	=item L<Event::ExecFlow>
		764
		765	High level API for event-based execution flow control.
		766
		767	=item L<Coro>
		768
		769	Has special support for AnyEvent via L<Coro::AnyEvent>.
		770
		771	=item L<AnyEvent::AIO>, L<IO::AIO>
		772
		773	Truly asynchronous I/O, should be in the toolbox of every event
		774	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
		775	together.
		776
		777	=item L<AnyEvent::BDB>, L<BDB>
		778
		779	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
		780	IO::AIO and AnyEvent together.
		781
		782	=item L<IO::Lambda>
		783
		784	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		785
		786	=back
462		787
463	=cut	788	=cut
464		789
465	package AnyEvent;	790	package AnyEvent;
466		791
467	no warnings;	792	no warnings;
468	use strict;	793	use strict;
469		794
470	use Carp;	795	use Carp;
471		796
472	our $VERSION = '3.3';	797	our $VERSION = '4.05';
473	our $MODEL;	798	our $MODEL;
474		799
475	our $AUTOLOAD;	800	our $AUTOLOAD;
476	our @ISA;	801	our @ISA;
477		802
		803	our @REGISTRY;
		804
		805	our $WIN32;
		806
		807	BEGIN {
		808	my $win32 = ! ! ($^O =~ /mswin32/i);
		809	eval "sub WIN32(){ $win32 }";
		810	}
		811
478	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	812	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
479		813
480	our @REGISTRY;	814	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
		815
		816	{
		817	my $idx;
		818	$PROTOCOL{$_} = ++$idx
		819	for reverse split /\s,\s/,
		820	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		821	}
481		822
482	my @models = (	823	my @models = (
483	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
484	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
485	[EV:: => AnyEvent::Impl::EV::],	824	[EV:: => AnyEvent::Impl::EV::],
486	[Event:: => AnyEvent::Impl::Event::],	825	[Event:: => AnyEvent::Impl::Event::],
487	[Glib:: => AnyEvent::Impl::Glib::],
488	[Tk:: => AnyEvent::Impl::Tk::],
489	[Wx:: => AnyEvent::Impl::POE::],
490	[Prima:: => AnyEvent::Impl::POE::],
491	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	826	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
492	# everything below here will not be autoprobed as the pureperl backend should work everywhere	827	# everything below here will not be autoprobed
		828	# as the pureperl backend should work everywhere
		829	# and is usually faster
		830	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		831	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
493	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	832	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
494	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	833	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
495	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	834	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		835	[Wx:: => AnyEvent::Impl::POE::],
		836	[Prima:: => AnyEvent::Impl::POE::],
496	);	837	);
497		838
498	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	839	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		840
		841	our @post_detect;
		842
		843	sub post_detect(&) {
		844	my ($cb) = @_;
		845
		846	if ($MODEL) {
		847	$cb->();
		848
		849	1
		850	} else {
		851	push @post_detect, $cb;
		852
		853	defined wantarray
		854	? bless \$cb, "AnyEvent::Util::PostDetect"
		855	: ()
		856	}
		857	}
		858
		859	sub AnyEvent::Util::PostDetect::DESTROY {
		860	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		861	}
499		862
500	sub detect() {	863	sub detect() {
501	unless ($MODEL) {	864	unless ($MODEL) {
502	no strict 'refs';	865	no strict 'refs';
		866	local $SIG{__DIE__};
503		867
504	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	868	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
505	my $model = "AnyEvent::Impl::$1";	869	my $model = "AnyEvent::Impl::$1";
506	if (eval "require $model") {	870	if (eval "require $model") {
507	$MODEL = $model;	871	$MODEL = $model;
…		…
537	last;	901	last;
538	}	902	}
539	}	903	}
540		904
541	$MODEL	905	$MODEL
542	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	906	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
543	}	907	}
544	}	908	}
545		909
546	unshift @ISA, $MODEL;	910	unshift @ISA, $MODEL;
547	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	911	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		912
		913	(shift @post_detect)->() while @post_detect;
548	}	914	}
549		915
550	$MODEL	916	$MODEL
551	}	917	}
552		918
…		…
562	$class->$func (@_);	928	$class->$func (@_);
563	}	929	}
564		930
565	package AnyEvent::Base;	931	package AnyEvent::Base;
566		932
		933	# default implementation for now and time
		934
		935	use Time::HiRes ();
		936
		937	sub time { Time::HiRes::time }
		938	sub now { Time::HiRes::time }
		939
567	# default implementation for ->condvar, ->wait, ->broadcast	940	# default implementation for ->condvar
568		941
569	sub condvar {	942	sub condvar {
570	bless \my $flag, "AnyEvent::Base::CondVar"	943	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
571	}
572
573	sub AnyEvent::Base::CondVar::broadcast {
574	${$_[0]}++;
575	}
576
577	sub AnyEvent::Base::CondVar::wait {
578	AnyEvent->one_event while !${$_[0]};
579	}	944	}
580		945
581	# default implementation for ->signal	946	# default implementation for ->signal
582		947
583	our %SIG_CB;	948	our %SIG_CB;
…		…
636	or Carp::croak "required option 'pid' is missing";	1001	or Carp::croak "required option 'pid' is missing";
637		1002
638	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1003	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
639		1004
640	unless ($WNOHANG) {	1005	unless ($WNOHANG) {
641	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1006	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
642	}	1007	}
643		1008
644	unless ($CHLD_W) {	1009	unless ($CHLD_W) {
645	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1010	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
646	# child could be a zombie already, so make at least one round	1011	# child could be a zombie already, so make at least one round
…		…
656	delete $PID_CB{$pid}{$cb};	1021	delete $PID_CB{$pid}{$cb};
657	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1022	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
658		1023
659	undef $CHLD_W unless keys %PID_CB;	1024	undef $CHLD_W unless keys %PID_CB;
660	}	1025	}
		1026
		1027	package AnyEvent::CondVar;
		1028
		1029	our @ISA = AnyEvent::CondVar::Base::;
		1030
		1031	package AnyEvent::CondVar::Base;
		1032
		1033	use overload
		1034	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1035	fallback => 1;
		1036
		1037	sub _send {
		1038	# nop
		1039	}
		1040
		1041	sub send {
		1042	my $cv = shift;
		1043	$cv->{_ae_sent} = [@_];
		1044	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1045	$cv->_send;
		1046	}
		1047
		1048	sub croak {
		1049	$_[0]{_ae_croak} = $_[1];
		1050	$_[0]->send;
		1051	}
		1052
		1053	sub ready {
		1054	$_[0]{_ae_sent}
		1055	}
		1056
		1057	sub _wait {
		1058	AnyEvent->one_event while !$_[0]{_ae_sent};
		1059	}
		1060
		1061	sub recv {
		1062	$_[0]->_wait;
		1063
		1064	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1065	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1066	}
		1067
		1068	sub cb {
		1069	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1070	$_[0]{_ae_cb}
		1071	}
		1072
		1073	sub begin {
		1074	++$_[0]{_ae_counter};
		1075	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1076	}
		1077
		1078	sub end {
		1079	return if --$_[0]{_ae_counter};
		1080	&{ $_[0]{_ae_end_cb} \|\| sub { $_[0]->send } };
		1081	}
		1082
		1083	# undocumented/compatibility with pre-3.4
		1084	*broadcast = \&send;
		1085	*wait = \&_wait;
661		1086
662	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1087	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
663		1088
664	This is an advanced topic that you do not normally need to use AnyEvent in	1089	This is an advanced topic that you do not normally need to use AnyEvent in
665	a module. This section is only of use to event loop authors who want to	1090	a module. This section is only of use to event loop authors who want to
…		…
722	model it chooses.	1147	model it chooses.
723		1148
724	=item C<PERL_ANYEVENT_MODEL>	1149	=item C<PERL_ANYEVENT_MODEL>
725		1150
726	This can be used to specify the event model to be used by AnyEvent, before	1151	This can be used to specify the event model to be used by AnyEvent, before
727	autodetection and -probing kicks in. It must be a string consisting	1152	auto detection and -probing kicks in. It must be a string consisting
728	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1153	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
729	and the resulting module name is loaded and if the load was successful,	1154	and the resulting module name is loaded and if the load was successful,
730	used as event model. If it fails to load AnyEvent will proceed with	1155	used as event model. If it fails to load AnyEvent will proceed with
731	autodetection and -probing.	1156	auto detection and -probing.
732		1157
733	This functionality might change in future versions.	1158	This functionality might change in future versions.
734		1159
735	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1160	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
736	could start your program like this:	1161	could start your program like this:
737		1162
738	PERL_ANYEVENT_MODEL=Perl perl ...	1163	PERL_ANYEVENT_MODEL=Perl perl ...
		1164
		1165	=item C<PERL_ANYEVENT_PROTOCOLS>
		1166
		1167	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1168	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1169	of auto probing).
		1170
		1171	Must be set to a comma-separated list of protocols or address families,
		1172	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1173	used, and preference will be given to protocols mentioned earlier in the
		1174	list.
		1175
		1176	This variable can effectively be used for denial-of-service attacks
		1177	against local programs (e.g. when setuid), although the impact is likely
		1178	small, as the program has to handle connection errors already-
		1179
		1180	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1181	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1182	- only support IPv4, never try to resolve or contact IPv6
		1183	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1184	IPv6, but prefer IPv6 over IPv4.
		1185
		1186	=item C<PERL_ANYEVENT_EDNS0>
		1187
		1188	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1189	for DNS. This extension is generally useful to reduce DNS traffic, but
		1190	some (broken) firewalls drop such DNS packets, which is why it is off by
		1191	default.
		1192
		1193	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1194	EDNS0 in its DNS requests.
		1195
		1196	=item C<PERL_ANYEVENT_MAX_FORKS>
		1197
		1198	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1199	will create in parallel.
739		1200
740	=back	1201	=back
741		1202
742	=head1 EXAMPLE PROGRAM	1203	=head1 EXAMPLE PROGRAM
743		1204
…		…
754	poll => 'r',	1215	poll => 'r',
755	cb => sub {	1216	cb => sub {
756	warn "io event <$_[0]>\n"; # will always output <r>	1217	warn "io event <$_[0]>\n"; # will always output <r>
757	chomp (my $input = <STDIN>); # read a line	1218	chomp (my $input = <STDIN>); # read a line
758	warn "read: $input\n"; # output what has been read	1219	warn "read: $input\n"; # output what has been read
759	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1220	$cv->send if $input =~ /^q/i; # quit program if /^q/i
760	},	1221	},
761	);	1222	);
762		1223
763	my $time_watcher; # can only be used once	1224	my $time_watcher; # can only be used once
764		1225
…		…
769	});	1230	});
770	}	1231	}
771		1232
772	new_timer; # create first timer	1233	new_timer; # create first timer
773		1234
774	$cv->wait; # wait until user enters /^q/i	1235	$cv->recv; # wait until user enters /^q/i
775		1236
776	=head1 REAL-WORLD EXAMPLE	1237	=head1 REAL-WORLD EXAMPLE
777		1238
778	Consider the L<Net::FCP> module. It features (among others) the following	1239	Consider the L<Net::FCP> module. It features (among others) the following
779	API calls, which are to freenet what HTTP GET requests are to http:	1240	API calls, which are to freenet what HTTP GET requests are to http:
…		…
829	syswrite $txn->{fh}, $txn->{request}	1290	syswrite $txn->{fh}, $txn->{request}
830	or die "connection or write error";	1291	or die "connection or write error";
831	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1292	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
832		1293
833	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1294	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
834	result and signals any possible waiters that the request ahs finished:	1295	result and signals any possible waiters that the request has finished:
835		1296
836	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1297	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
837		1298
838	if (end-of-file or data complete) {	1299	if (end-of-file or data complete) {
839	$txn->{result} = $txn->{buf};	1300	$txn->{result} = $txn->{buf};
840	$txn->{finished}->broadcast;	1301	$txn->{finished}->send;
841	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1302	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
842	}	1303	}
843		1304
844	The C<result> method, finally, just waits for the finished signal (if the	1305	The C<result> method, finally, just waits for the finished signal (if the
845	request was already finished, it doesn't wait, of course, and returns the	1306	request was already finished, it doesn't wait, of course, and returns the
846	data:	1307	data:
847		1308
848	$txn->{finished}->wait;	1309	$txn->{finished}->recv;
849	return $txn->{result};	1310	return $txn->{result};
850		1311
851	The actual code goes further and collects all errors (C<die>s, exceptions)	1312	The actual code goes further and collects all errors (C<die>s, exceptions)
852	that occured during request processing. The C<result> method detects	1313	that occurred during request processing. The C<result> method detects
853	whether an exception as thrown (it is stored inside the $txn object)	1314	whether an exception as thrown (it is stored inside the $txn object)
854	and just throws the exception, which means connection errors and other	1315	and just throws the exception, which means connection errors and other
855	problems get reported tot he code that tries to use the result, not in a	1316	problems get reported tot he code that tries to use the result, not in a
856	random callback.	1317	random callback.
857		1318
…		…
888		1349
889	my $quit = AnyEvent->condvar;	1350	my $quit = AnyEvent->condvar;
890		1351
891	$fcp->txn_client_get ($url)->cb (sub {	1352	$fcp->txn_client_get ($url)->cb (sub {
892	...	1353	...
893	$quit->broadcast;	1354	$quit->send;
894	});	1355	});
895		1356
896	$quit->wait;	1357	$quit->recv;
897		1358
898		1359
899	=head1 BENCHMARKS	1360	=head1 BENCHMARKS
900		1361
901	To give you an idea of the performance and overheads that AnyEvent adds	1362	To give you an idea of the performance and overheads that AnyEvent adds
…		…
903	of various event loops I prepared some benchmarks.	1364	of various event loops I prepared some benchmarks.
904		1365
905	=head2 BENCHMARKING ANYEVENT OVERHEAD	1366	=head2 BENCHMARKING ANYEVENT OVERHEAD
906		1367
907	Here is a benchmark of various supported event models used natively and	1368	Here is a benchmark of various supported event models used natively and
908	through anyevent. The benchmark creates a lot of timers (with a zero	1369	through AnyEvent. The benchmark creates a lot of timers (with a zero
909	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1370	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
910	which it is), lets them fire exactly once and destroys them again.	1371	which it is), lets them fire exactly once and destroys them again.
911		1372
912	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1373	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
913	distribution.	1374	distribution.
…		…
930	all watchers, to avoid adding memory overhead. That means closure creation	1391	all watchers, to avoid adding memory overhead. That means closure creation
931	and memory usage is not included in the figures.	1392	and memory usage is not included in the figures.
932		1393
933	I<invoke> is the time, in microseconds, used to invoke a simple	1394	I<invoke> is the time, in microseconds, used to invoke a simple
934	callback. The callback simply counts down a Perl variable and after it was	1395	callback. The callback simply counts down a Perl variable and after it was
935	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1396	invoked "watcher" times, it would C<< ->send >> a condvar once to
936	signal the end of this phase.	1397	signal the end of this phase.
937		1398
938	I<destroy> is the time, in microseconds, that it takes to destroy a single	1399	I<destroy> is the time, in microseconds, that it takes to destroy a single
939	watcher.	1400	watcher.
940		1401
…		…
944	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1405	EV/EV 400000 244 0.56 0.46 0.31 EV native interface
945	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1406	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers
946	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1407	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal
947	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1408	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation
948	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1409	Event/Event 16000 516 31.88 31.30 0.85 Event native interface
949	Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers	1410	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers
950	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1411	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour
951	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1412	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers
952	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1413	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event
953	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1414	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select
954		1415
…		…
958	well. For example, a select-based event loop (such as the pure perl one)	1419	well. For example, a select-based event loop (such as the pure perl one)
959	can never compete with an event loop that uses epoll when the number of	1420	can never compete with an event loop that uses epoll when the number of
960	file descriptors grows high. In this benchmark, all events become ready at	1421	file descriptors grows high. In this benchmark, all events become ready at
961	the same time, so select/poll-based implementations get an unnatural speed	1422	the same time, so select/poll-based implementations get an unnatural speed
962	boost.	1423	boost.
		1424
		1425	Also, note that the number of watchers usually has a nonlinear effect on
		1426	overall speed, that is, creating twice as many watchers doesn't take twice
		1427	the time - usually it takes longer. This puts event loops tested with a
		1428	higher number of watchers at a disadvantage.
		1429
		1430	To put the range of results into perspective, consider that on the
		1431	benchmark machine, handling an event takes roughly 1600 CPU cycles with
		1432	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
		1433	cycles with POE.
963		1434
964	C<EV> is the sole leader regarding speed and memory use, which are both	1435	C<EV> is the sole leader regarding speed and memory use, which are both
965	maximal/minimal, respectively. Even when going through AnyEvent, it uses	1436	maximal/minimal, respectively. Even when going through AnyEvent, it uses
966	far less memory than any other event loop and is still faster than Event	1437	far less memory than any other event loop and is still faster than Event
967	natively.	1438	natively.
…		…
990	file descriptor is dup()ed for each watcher. This shows that the dup()	1461	file descriptor is dup()ed for each watcher. This shows that the dup()
991	employed by some adaptors is not a big performance issue (it does incur a	1462	employed by some adaptors is not a big performance issue (it does incur a
992	hidden memory cost inside the kernel which is not reflected in the figures	1463	hidden memory cost inside the kernel which is not reflected in the figures
993	above).	1464	above).
994		1465
995	C<POE>, regardless of underlying event loop (whether using its pure	1466	C<POE>, regardless of underlying event loop (whether using its pure perl
996	perl select-based backend or the Event module, the POE-EV backend	1467	select-based backend or the Event module, the POE-EV backend couldn't
997	couldn't be tested because it wasn't working) shows abysmal performance	1468	be tested because it wasn't working) shows abysmal performance and
998	and memory usage: Watchers use almost 30 times as much memory as	1469	memory usage with AnyEvent: Watchers use almost 30 times as much memory
999	EV watchers, and 10 times as much memory as Event (the high memory	1470	as EV watchers, and 10 times as much memory as Event (the high memory
1000	requirements are caused by requiring a session for each watcher). Watcher	1471	requirements are caused by requiring a session for each watcher). Watcher
1001	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1472	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1473	implementation.
		1474
1002	implementation. The design of the POE adaptor class in AnyEvent can not	1475	The design of the POE adaptor class in AnyEvent can not really account
1003	really account for this, as session creation overhead is small compared	1476	for the performance issues, though, as session creation overhead is
1004	to execution of the state machine, which is coded pretty optimally within	1477	small compared to execution of the state machine, which is coded pretty
1005	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1478	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1479	using multiple sessions is not a good approach, especially regarding
		1480	memory usage, even the author of POE could not come up with a faster
		1481	design).
1006		1482
1007	=head3 Summary	1483	=head3 Summary
1008		1484
1009	=over 4	1485	=over 4
1010		1486
…		…
1021		1497
1022	=back	1498	=back
1023		1499
1024	=head2 BENCHMARKING THE LARGE SERVER CASE	1500	=head2 BENCHMARKING THE LARGE SERVER CASE
1025		1501
1026	This benchmark atcually benchmarks the event loop itself. It works by	1502	This benchmark actually benchmarks the event loop itself. It works by
1027	creating a number of "servers": each server consists of a socketpair, a	1503	creating a number of "servers": each server consists of a socket pair, a
1028	timeout watcher that gets reset on activity (but never fires), and an I/O	1504	timeout watcher that gets reset on activity (but never fires), and an I/O
1029	watcher waiting for input on one side of the socket. Each time the socket	1505	watcher waiting for input on one side of the socket. Each time the socket
1030	watcher reads a byte it will write that byte to a random other "server".	1506	watcher reads a byte it will write that byte to a random other "server".
1031		1507
1032	The effect is that there will be a lot of I/O watchers, only part of which	1508	The effect is that there will be a lot of I/O watchers, only part of which
1033	are active at any one point (so there is a constant number of active	1509	are active at any one point (so there is a constant number of active
1034	fds for each loop iterstaion, but which fds these are is random). The	1510	fds for each loop iteration, but which fds these are is random). The
1035	timeout is reset each time something is read because that reflects how	1511	timeout is reset each time something is read because that reflects how
1036	most timeouts work (and puts extra pressure on the event loops).	1512	most timeouts work (and puts extra pressure on the event loops).
1037		1513
1038	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1514	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1039	(1%) are active. This mirrors the activity of large servers with many	1515	(1%) are active. This mirrors the activity of large servers with many
1040	connections, most of which are idle at any one point in time.	1516	connections, most of which are idle at any one point in time.
1041		1517
1042	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1518	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1043	distribution.	1519	distribution.
…		…
1045	=head3 Explanation of the columns	1521	=head3 Explanation of the columns
1046		1522
1047	I<sockets> is the number of sockets, and twice the number of "servers" (as	1523	I<sockets> is the number of sockets, and twice the number of "servers" (as
1048	each server has a read and write socket end).	1524	each server has a read and write socket end).
1049		1525
1050	I<create> is the time it takes to create a socketpair (which is	1526	I<create> is the time it takes to create a socket pair (which is
1051	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1527	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1052		1528
1053	I<request>, the most important value, is the time it takes to handle a	1529	I<request>, the most important value, is the time it takes to handle a
1054	single "request", that is, reading the token from the pipe and forwarding	1530	single "request", that is, reading the token from the pipe and forwarding
1055	it to another server. This includes deleting the old timeout and creating	1531	it to another server. This includes deleting the old timeout and creating
…		…
1057		1533
1058	=head3 Results	1534	=head3 Results
1059		1535
1060	name sockets create request	1536	name sockets create request
1061	EV 20000 69.01 11.16	1537	EV 20000 69.01 11.16
1062	Perl 20000 75.28 112.76	1538	Perl 20000 73.32 35.87
1063	Event 20000 212.62 257.32	1539	Event 20000 212.62 257.32
1064	Glib 20000 651.16 1896.30	1540	Glib 20000 651.16 1896.30
1065	POE 20000 349.67 12317.24 uses POE::Loop::Event	1541	POE 20000 349.67 12317.24 uses POE::Loop::Event
1066		1542
1067	=head3 Discussion	1543	=head3 Discussion
…		…
1089		1565
1090	=head3 Summary	1566	=head3 Summary
1091		1567
1092	=over 4	1568	=over 4
1093		1569
1094	=item * The pure perl implementation performs extremely well, considering	1570	=item * The pure perl implementation performs extremely well.
1095	that it uses select.
1096		1571
1097	=item * Avoid Glib or POE in large projects where performance matters.	1572	=item * Avoid Glib or POE in large projects where performance matters.
1098		1573
1099	=back	1574	=back
1100		1575
…		…
1113		1588
1114	=head3 Results	1589	=head3 Results
1115		1590
1116	name sockets create request	1591	name sockets create request
1117	EV 16 20.00 6.54	1592	EV 16 20.00 6.54
		1593	Perl 16 25.75 12.62
1118	Event 16 81.27 35.86	1594	Event 16 81.27 35.86
1119	Glib 16 32.63 15.48	1595	Glib 16 32.63 15.48
1120	Perl 16 24.62 162.37
1121	POE 16 261.87 276.28 uses POE::Loop::Event	1596	POE 16 261.87 276.28 uses POE::Loop::Event
1122		1597
1123	=head3 Discussion	1598	=head3 Discussion
1124		1599
1125	The benchmark tries to test the performance of a typical small	1600	The benchmark tries to test the performance of a typical small
1126	server. While knowing how various event loops perform is interesting, keep	1601	server. While knowing how various event loops perform is interesting, keep
1127	in mind that their overhead in this case is usually not as important, due	1602	in mind that their overhead in this case is usually not as important, due
1128	to the small absolute number of watchers.	1603	to the small absolute number of watchers (that is, you need efficiency and
		1604	speed most when you have lots of watchers, not when you only have a few of
		1605	them).
1129		1606
1130	EV is again fastest.	1607	EV is again fastest.
1131		1608
1132	The C-based event loops Event and Glib come in second this time, as the	1609	Perl again comes second. It is noticeably faster than the C-based event
1133	overhead of running an iteration is much smaller in C than in Perl (little	1610	loops Event and Glib, although the difference is too small to really
1134	code to execute in the inner loop, and perl's function calling overhead is	1611	matter.
1135	high, and updating all the data structures is costly).
1136		1612
1137	The pure perl event loop is much slower, but still competitive.
1138
1139	POE also performs much better in this case, but is is stillf ar behind the	1613	POE also performs much better in this case, but is is still far behind the
1140	others.	1614	others.
1141		1615
1142	=head3 Summary	1616	=head3 Summary
1143		1617
1144	=over 4	1618	=over 4
…		…
1150		1624
1151		1625
1152	=head1 FORK	1626	=head1 FORK
1153		1627
1154	Most event libraries are not fork-safe. The ones who are usually are	1628	Most event libraries are not fork-safe. The ones who are usually are
1155	because they are so inefficient. Only L<EV> is fully fork-aware.	1629	because they rely on inefficient but fork-safe C<select> or C<poll>
		1630	calls. Only L<EV> is fully fork-aware.
1156		1631
1157	If you have to fork, you must either do so I<before> creating your first	1632	If you have to fork, you must either do so I<before> creating your first
1158	watcher OR you must not use AnyEvent at all in the child.	1633	watcher OR you must not use AnyEvent at all in the child.
1159		1634
1160		1635
…		…
1172		1647
1173	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1648	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1174		1649
1175	use AnyEvent;	1650	use AnyEvent;
1176		1651
		1652	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1653	be used to probe what backend is used and gain other information (which is
		1654	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
		1655
1177		1656
1178	=head1 SEE ALSO	1657	=head1 SEE ALSO
1179		1658
1180	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1659	Utility functions: L<AnyEvent::Util>.
1181	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1660
		1661	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1182	L<Event::Lib>, L<Qt>, L<POE>.	1662	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1183		1663
1184	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1664	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1185	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1665	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1186	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1666	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1187	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1667	L<AnyEvent::Impl::POE>.
1188		1668
		1669	Non-blocking file handles, sockets, TCP clients and
		1670	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1671
		1672	Asynchronous DNS: L<AnyEvent::DNS>.
		1673
		1674	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1675
1189	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1676	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1190		1677
1191		1678
1192	=head1 AUTHOR	1679	=head1 AUTHOR
1193		1680
1194	Marc Lehmann <schmorp@schmorp.de>	1681	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.94 by root, Sat Apr 26 04:33:51 2008 UTC vs. Revision 1.143 by root, Wed May 28 23:57:38 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.94 by root, Sat Apr 26 04:33:51 2008 UTC vs.
Revision 1.143 by root, Wed May 28 23:57:38 2008 UTC