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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.96 by root, Sat Apr 26 11:16:16 2008 UTC vs.
Revision 1.147 by root, Fri May 30 21:43:26 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, i.e. each call
		249	will check the system clock, which usually gets updated frequently.
		250
		251	=item AnyEvent->now
		252
		253	This also returns the "current wallclock time", but unlike C<time>, above,
		254	this value might change only once per event loop iteration, depending on
		255	the event loop (most return the same time as C<time>, above). This is the
		256	time that AnyEvent's timers get scheduled against.
		257
		258	I<In almost all cases (in all cases if you don't care), this is the
		259	function to call when you want to know the current time.>
		260
		261	This function is also often faster then C<< AnyEvent->time >>, and
		262	thus the preferred method if you want some timestamp (for example,
		263	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		264
		265	The rest of this section is only of relevance if you try to be very exact
		266	with your timing, you can skip it without bad conscience.
		267
		268	For a practical example of when these times differ, consider L<Event::Lib>
		269	and L<EV> and the following set-up:
		270
		271	The event loop is running and has just invoked one of your callback at
		272	time=500 (assume no other callbacks delay processing). In your callback,
		273	you wait a second by executing C<sleep 1> (blocking the process for a
		274	second) and then (at time=501) you create a relative timer that fires
		275	after three seconds.
		276
		277	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		278	both return C<501>, because that is the current time, and the timer will
		279	be scheduled to fire at time=504 (C<501> + C<3>).
		280
		281	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		282	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		283	last event processing phase started. With L<EV>, your timer gets scheduled
		284	to run at time=503 (C<500> + C<3>).
		285
		286	In one sense, L<Event::Lib> is more exact, as it uses the current time
		287	regardless of any delays introduced by event processing. However, most
		288	callbacks do not expect large delays in processing, so this causes a
		289	higher drift (and a lot more system calls to get the current time).
		290
		291	In another sense, L<EV> is more exact, as your timer will be scheduled at
		292	the same time, regardless of how long event processing actually took.
		293
		294	In either case, if you care (and in most cases, you don't), then you
		295	can get whatever behaviour you want with any event loop, by taking the
		296	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		297	account.
		298
		299	=back
		300
233	=head2 SIGNAL WATCHERS	301	=head2 SIGNAL WATCHERS
234		302
235	You can watch for signals using a signal watcher, C<signal> is the signal	303	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	304	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
237	be invoked whenever a signal occurs.	305	be invoked whenever a signal occurs.
238		306
239	Although the callback might get passed parameters, their value and	307	Although the callback might get passed parameters, their value and
240	presence is undefined and you cannot rely on them. Portable AnyEvent	308	presence is undefined and you cannot rely on them. Portable AnyEvent
241	callbacks cannot use arguments passed to signal watcher callbacks.	309	callbacks cannot use arguments passed to signal watcher callbacks.
242		310
243	Multiple signal occurances can be clumped together into one callback	311	Multiple signal occurrences can be clumped together into one callback
244	invocation, and callback invocation will be synchronous. synchronous means	312	invocation, and callback invocation will be synchronous. Synchronous means
245	that it might take a while until the signal gets handled by the process,	313	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.	314	but it is guaranteed not to interrupt any other callbacks.
247		315
248	The main advantage of using these watchers is that you can share a signal	316	The main advantage of using these watchers is that you can share a signal
249	between multiple watchers.	317	between multiple watchers.
250		318
251	This watcher might use C<%SIG>, so programs overwriting those signals	319	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
280		348
281	Example: fork a process and wait for it	349	Example: fork a process and wait for it
282		350
283	my $done = AnyEvent->condvar;	351	my $done = AnyEvent->condvar;
284		352
285	AnyEvent::detect; # force event module to be initialised
286
287	my $pid = fork or exit 5;	353	my $pid = fork or exit 5;
288		354
289	my $w = AnyEvent->child (	355	my $w = AnyEvent->child (
290	pid => $pid,	356	pid => $pid,
291	cb => sub {	357	cb => sub {
292	my ($pid, $status) = @_;	358	my ($pid, $status) = @_;
293	warn "pid $pid exited with status $status";	359	warn "pid $pid exited with status $status";
294	$done->broadcast;	360	$done->send;
295	},	361	},
296	);	362	);
297		363
298	# do something else, then wait for process exit	364	# do something else, then wait for process exit
299	$done->wait;	365	$done->recv;
300		366
301	=head2 CONDITION VARIABLES	367	=head2 CONDITION VARIABLES
302		368
		369	If you are familiar with some event loops you will know that all of them
		370	require you to run some blocking "loop", "run" or similar function that
		371	will actively watch for new events and call your callbacks.
		372
		373	AnyEvent is different, it expects somebody else to run the event loop and
		374	will only block when necessary (usually when told by the user).
		375
		376	The instrument to do that is called a "condition variable", so called
		377	because they represent a condition that must become true.
		378
303	Condition variables can be created by calling the C<< AnyEvent->condvar >>	379	Condition variables can be created by calling the C<< AnyEvent->condvar
304	method without any arguments.	380	>> method, usually without arguments. The only argument pair allowed is
		381	C<cb>, which specifies a callback to be called when the condition variable
		382	becomes true.
305		383
306	A condition variable waits for a condition - precisely that the C<<	384	After creation, the condition variable is "false" until it becomes "true"
307	->broadcast >> method has been called.	385	by calling the C<send> method (or calling the condition variable as if it
		386	were a callback, read about the caveats in the description for the C<<
		387	->send >> method).
308		388
309	They are very useful to signal that a condition has been fulfilled, for	389	Condition variables are similar to callbacks, except that you can
		390	optionally wait for them. They can also be called merge points - points
		391	in time where multiple outstanding events have been processed. And yet
		392	another way to call them is transactions - each condition variable can be
		393	used to represent a transaction, which finishes at some point and delivers
		394	a result.
		395
		396	Condition variables are very useful to signal that something has finished,
310	example, if you write a module that does asynchronous http requests,	397	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	398	then a condition variable would be the ideal candidate to signal the
312	availability of results.	399	availability of results. The user can either act when the callback is
		400	called or can synchronously C<< ->recv >> for the results.
313		401
314	You can also use condition variables to block your main program until	402	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	403	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<<	404	could C<< ->recv >> in your main program until the user clicks the Quit
317	->broadcast >> the "quit" event.	405	button of your app, which would C<< ->send >> the "quit" event.
318		406
319	Note that condition variables recurse into the event loop - if you have	407	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	408	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	409	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,	410	you should avoid making a blocking wait yourself, at least in callbacks,
323	as this asks for trouble.	411	as this asks for trouble.
324		412
325	This object has two methods:	413	Condition variables are represented by hash refs in perl, and the keys
		414	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		415	easy (it is often useful to build your own transaction class on top of
		416	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		417	it's C<new> method in your own C<new> method.
		418
		419	There are two "sides" to a condition variable - the "producer side" which
		420	eventually calls C<< -> send >>, and the "consumer side", which waits
		421	for the send to occur.
		422
		423	Example: wait for a timer.
		424
		425	# wait till the result is ready
		426	my $result_ready = AnyEvent->condvar;
		427
		428	# do something such as adding a timer
		429	# or socket watcher the calls $result_ready->send
		430	# when the "result" is ready.
		431	# in this case, we simply use a timer:
		432	my $w = AnyEvent->timer (
		433	after => 1,
		434	cb => sub { $result_ready->send },
		435	);
		436
		437	# this "blocks" (while handling events) till the callback
		438	# calls send
		439	$result_ready->recv;
		440
		441	Example: wait for a timer, but take advantage of the fact that
		442	condition variables are also code references.
		443
		444	my $done = AnyEvent->condvar;
		445	my $delay = AnyEvent->timer (after => 5, cb => $done);
		446	$done->recv;
		447
		448	=head3 METHODS FOR PRODUCERS
		449
		450	These methods should only be used by the producing side, i.e. the
		451	code/module that eventually sends the signal. Note that it is also
		452	the producer side which creates the condvar in most cases, but it isn't
		453	uncommon for the consumer to create it as well.
326		454
327	=over 4	455	=over 4
328		456
		457	=item $cv->send (...)
		458
		459	Flag the condition as ready - a running C<< ->recv >> and all further
		460	calls to C<recv> will (eventually) return after this method has been
		461	called. If nobody is waiting the send will be remembered.
		462
		463	If a callback has been set on the condition variable, it is called
		464	immediately from within send.
		465
		466	Any arguments passed to the C<send> call will be returned by all
		467	future C<< ->recv >> calls.
		468
		469	Condition variables are overloaded so one can call them directly
		470	(as a code reference). Calling them directly is the same as calling
		471	C<send>. Note, however, that many C-based event loops do not handle
		472	overloading, so as tempting as it may be, passing a condition variable
		473	instead of a callback does not work. Both the pure perl and EV loops
		474	support overloading, however, as well as all functions that use perl to
		475	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		476	example).
		477
		478	=item $cv->croak ($error)
		479
		480	Similar to send, but causes all call's to C<< ->recv >> to invoke
		481	C<Carp::croak> with the given error message/object/scalar.
		482
		483	This can be used to signal any errors to the condition variable
		484	user/consumer.
		485
		486	=item $cv->begin ([group callback])
		487
329	=item $cv->wait	488	=item $cv->end
330		489
331	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	490	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		491
		492	These two methods can be used to combine many transactions/events into
		493	one. For example, a function that pings many hosts in parallel might want
		494	to use a condition variable for the whole process.
		495
		496	Every call to C<< ->begin >> will increment a counter, and every call to
		497	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		498	>>, the (last) callback passed to C<begin> will be executed. That callback
		499	is I<supposed> to call C<< ->send >>, but that is not required. If no
		500	callback was set, C<send> will be called without any arguments.
		501
		502	Let's clarify this with the ping example:
		503
		504	my $cv = AnyEvent->condvar;
		505
		506	my %result;
		507	$cv->begin (sub { $cv->send (\%result) });
		508
		509	for my $host (@list_of_hosts) {
		510	$cv->begin;
		511	ping_host_then_call_callback $host, sub {
		512	$result{$host} = ...;
		513	$cv->end;
		514	};
		515	}
		516
		517	$cv->end;
		518
		519	This code fragment supposedly pings a number of hosts and calls
		520	C<send> after results for all then have have been gathered - in any
		521	order. To achieve this, the code issues a call to C<begin> when it starts
		522	each ping request and calls C<end> when it has received some result for
		523	it. Since C<begin> and C<end> only maintain a counter, the order in which
		524	results arrive is not relevant.
		525
		526	There is an additional bracketing call to C<begin> and C<end> outside the
		527	loop, which serves two important purposes: first, it sets the callback
		528	to be called once the counter reaches C<0>, and second, it ensures that
		529	C<send> is called even when C<no> hosts are being pinged (the loop
		530	doesn't execute once).
		531
		532	This is the general pattern when you "fan out" into multiple subrequests:
		533	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		534	is called at least once, and then, for each subrequest you start, call
		535	C<begin> and for each subrequest you finish, call C<end>.
		536
		537	=back
		538
		539	=head3 METHODS FOR CONSUMERS
		540
		541	These methods should only be used by the consuming side, i.e. the
		542	code awaits the condition.
		543
		544	=over 4
		545
		546	=item $cv->recv
		547
		548	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
332	called on c<$cv>, while servicing other watchers normally.	549	>> methods have been called on c<$cv>, while servicing other watchers
		550	normally.
333		551
334	You can only wait once on a condition - additional calls will return	552	You can only wait once on a condition - additional calls are valid but
335	immediately.	553	will return immediately.
		554
		555	If an error condition has been set by calling C<< ->croak >>, then this
		556	function will call C<croak>.
		557
		558	In list context, all parameters passed to C<send> will be returned,
		559	in scalar context only the first one will be returned.
336		560
337	Not all event models support a blocking wait - some die in that case	561	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	562	(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	563	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	564	caller decide whether the call will block or not (for example, by coupling
341	condition variables with some kind of request results and supporting	565	condition variables with some kind of request results and supporting
342	callbacks so the caller knows that getting the result will not block,	566	callbacks so the caller knows that getting the result will not block,
343	while still suppporting blocking waits if the caller so desires).	567	while still supporting blocking waits if the caller so desires).
344		568
345	Another reason I<never> to C<< ->wait >> in a module is that you cannot	569	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	570	sensibly have two C<< ->recv >>'s in parallel, as that would require
347	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	571	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
348	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	572	can supply.
349	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
350	from different coroutines, however).
351		573
352	=item $cv->broadcast	574	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		575	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		576	versions and also integrates coroutines into AnyEvent, making blocking
		577	C<< ->recv >> calls perfectly safe as long as they are done from another
		578	coroutine (one that doesn't run the event loop).
353		579
354	Flag the condition as ready - a running C<< ->wait >> and all further	580	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	581	only calling C<< ->recv >> from within that callback (or at a later
356	called. If nobody is waiting the broadcast will be remembered..	582	time). This will work even when the event loop does not support blocking
		583	waits otherwise.
		584
		585	=item $bool = $cv->ready
		586
		587	Returns true when the condition is "true", i.e. whether C<send> or
		588	C<croak> have been called.
		589
		590	=item $cb = $cv->cb ([new callback])
		591
		592	This is a mutator function that returns the callback set and optionally
		593	replaces it before doing so.
		594
		595	The callback will be called when the condition becomes "true", i.e. when
		596	C<send> or C<croak> are called. Calling C<recv> inside the callback
		597	or at any later time is guaranteed not to block.
357		598
358	=back	599	=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	$result_ready->wait;
377		600
378	=head1 GLOBAL VARIABLES AND FUNCTIONS	601	=head1 GLOBAL VARIABLES AND FUNCTIONS
379		602
380	=over 4	603	=over 4
381		604
…		…
387	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	610	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
388	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	611	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
389		612
390	The known classes so far are:	613	The known classes so far are:
391		614
392	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
393	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
394	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	615	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
395	AnyEvent::Impl::Event based on Event, second best choice.	616	AnyEvent::Impl::Event based on Event, second best choice.
		617	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
396	AnyEvent::Impl::Glib based on Glib, third-best choice.	618	AnyEvent::Impl::Glib based on Glib, third-best choice.
397	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
398	AnyEvent::Impl::Tk based on Tk, very bad choice.	619	AnyEvent::Impl::Tk based on Tk, very bad choice.
399	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	620	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
400	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	621	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
401	AnyEvent::Impl::POE based on POE, not generic enough for full support.	622	AnyEvent::Impl::POE based on POE, not generic enough for full support.
402		623
…		…
415	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	636	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
416	if necessary. You should only call this function right before you would	637	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	638	have created an AnyEvent watcher anyway, that is, as late as possible at
418	runtime.	639	runtime.
419		640
		641	=item $guard = AnyEvent::post_detect { BLOCK }
		642
		643	Arranges for the code block to be executed as soon as the event model is
		644	autodetected (or immediately if this has already happened).
		645
		646	If called in scalar or list context, then it creates and returns an object
		647	that automatically removes the callback again when it is destroyed. See
		648	L<Coro::BDB> for a case where this is useful.
		649
		650	=item @AnyEvent::post_detect
		651
		652	If there are any code references in this array (you can C<push> to it
		653	before or after loading AnyEvent), then they will called directly after
		654	the event loop has been chosen.
		655
		656	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		657	if it contains a true value then the event loop has already been detected,
		658	and the array will be ignored.
		659
		660	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		661
420	=back	662	=back
421		663
422	=head1 WHAT TO DO IN A MODULE	664	=head1 WHAT TO DO IN A MODULE
423		665
424	As a module author, you should C<use AnyEvent> and call AnyEvent methods	666	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	669	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	670	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	671	by calling AnyEvent in your module body you force the user of your module
430	to load the event module first.	672	to load the event module first.
431		673
432	Never call C<< ->wait >> on a condition variable unless you I<know> that	674	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	675	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	676	because it will stall the whole program, and the whole point of using
435	events is to stay interactive.	677	events is to stay interactive.
436		678
437	It is fine, however, to call C<< ->wait >> when the user of your module	679	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	680	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 >>	681	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).	682	freely, as the user of your module knows what she is doing. always).
441		683
442	=head1 WHAT TO DO IN THE MAIN PROGRAM	684	=head1 WHAT TO DO IN THE MAIN PROGRAM
443		685
444	There will always be a single main program - the only place that should	686	There will always be a single main program - the only place that should
…		…
446		688
447	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	689	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	690	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.	691	decide which implementation to chose if some module relies on it.
450		692
451	If the main program relies on a specific event model. For example, in	693	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	694	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	695	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	696	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	697	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	698	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.	699	might chose the wrong one unless you load the correct one yourself.
458		700
459	You can chose to use a rather inefficient pure-perl implementation by	701	You can chose to use a pure-perl implementation by loading the
460	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	702	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
461	behaviour everywhere, but letting AnyEvent chose is generally better.	703	everywhere, but letting AnyEvent chose the model is generally better.
		704
		705	=head2 MAINLOOP EMULATION
		706
		707	Sometimes (often for short test scripts, or even standalone programs who
		708	only want to use AnyEvent), you do not want to run a specific event loop.
		709
		710	In that case, you can use a condition variable like this:
		711
		712	AnyEvent->condvar->recv;
		713
		714	This has the effect of entering the event loop and looping forever.
		715
		716	Note that usually your program has some exit condition, in which case
		717	it is better to use the "traditional" approach of storing a condition
		718	variable somewhere, waiting for it, and sending it when the program should
		719	exit cleanly.
		720
		721
		722	=head1 OTHER MODULES
		723
		724	The following is a non-exhaustive list of additional modules that use
		725	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		726	in the same program. Some of the modules come with AnyEvent, some are
		727	available via CPAN.
		728
		729	=over 4
		730
		731	=item L<AnyEvent::Util>
		732
		733	Contains various utility functions that replace often-used but blocking
		734	functions such as C<inet_aton> by event-/callback-based versions.
		735
		736	=item L<AnyEvent::Handle>
		737
		738	Provide read and write buffers and manages watchers for reads and writes.
		739
		740	=item L<AnyEvent::Socket>
		741
		742	Provides various utility functions for (internet protocol) sockets,
		743	addresses and name resolution. Also functions to create non-blocking tcp
		744	connections or tcp servers, with IPv6 and SRV record support and more.
		745
		746	=item L<AnyEvent::DNS>
		747
		748	Provides rich asynchronous DNS resolver capabilities.
		749
		750	=item L<AnyEvent::HTTPD>
		751
		752	Provides a simple web application server framework.
		753
		754	=item L<AnyEvent::FastPing>
		755
		756	The fastest ping in the west.
		757
		758	=item L<Net::IRC3>
		759
		760	AnyEvent based IRC client module family.
		761
		762	=item L<Net::XMPP2>
		763
		764	AnyEvent based XMPP (Jabber protocol) module family.
		765
		766	=item L<Net::FCP>
		767
		768	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		769	of AnyEvent.
		770
		771	=item L<Event::ExecFlow>
		772
		773	High level API for event-based execution flow control.
		774
		775	=item L<Coro>
		776
		777	Has special support for AnyEvent via L<Coro::AnyEvent>.
		778
		779	=item L<AnyEvent::AIO>, L<IO::AIO>
		780
		781	Truly asynchronous I/O, should be in the toolbox of every event
		782	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
		783	together.
		784
		785	=item L<AnyEvent::BDB>, L<BDB>
		786
		787	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
		788	IO::AIO and AnyEvent together.
		789
		790	=item L<IO::Lambda>
		791
		792	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		793
		794	=back
462		795
463	=cut	796	=cut
464		797
465	package AnyEvent;	798	package AnyEvent;
466		799
467	no warnings;	800	no warnings;
468	use strict;	801	use strict;
469		802
470	use Carp;	803	use Carp;
471		804
472	our $VERSION = '3.3';	805	our $VERSION = 4.11;
473	our $MODEL;	806	our $MODEL;
474		807
475	our $AUTOLOAD;	808	our $AUTOLOAD;
476	our @ISA;	809	our @ISA;
477		810
		811	our @REGISTRY;
		812
		813	our $WIN32;
		814
		815	BEGIN {
		816	my $win32 = ! ! ($^O =~ /mswin32/i);
		817	eval "sub WIN32(){ $win32 }";
		818	}
		819
478	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	820	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
479		821
480	our @REGISTRY;	822	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
		823
		824	{
		825	my $idx;
		826	$PROTOCOL{$_} = ++$idx
		827	for reverse split /\s,\s/,
		828	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		829	}
481		830
482	my @models = (	831	my @models = (
483	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
484	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
485	[EV:: => AnyEvent::Impl::EV::],	832	[EV:: => AnyEvent::Impl::EV::],
486	[Event:: => AnyEvent::Impl::Event::],	833	[Event:: => AnyEvent::Impl::Event::],
487	[Glib:: => AnyEvent::Impl::Glib::],
488	[Tk:: => AnyEvent::Impl::Tk::],
489	[Wx:: => AnyEvent::Impl::POE::],
490	[Prima:: => AnyEvent::Impl::POE::],
491	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	834	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
492	# everything below here will not be autoprobed as the pureperl backend should work everywhere	835	# everything below here will not be autoprobed
		836	# as the pureperl backend should work everywhere
		837	# and is usually faster
		838	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		839	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
493	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	840	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
494	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	841	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
495	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	842	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		843	[Wx:: => AnyEvent::Impl::POE::],
		844	[Prima:: => AnyEvent::Impl::POE::],
496	);	845	);
497		846
498	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	847	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		848
		849	our @post_detect;
		850
		851	sub post_detect(&) {
		852	my ($cb) = @_;
		853
		854	if ($MODEL) {
		855	$cb->();
		856
		857	1
		858	} else {
		859	push @post_detect, $cb;
		860
		861	defined wantarray
		862	? bless \$cb, "AnyEvent::Util::PostDetect"
		863	: ()
		864	}
		865	}
		866
		867	sub AnyEvent::Util::PostDetect::DESTROY {
		868	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		869	}
499		870
500	sub detect() {	871	sub detect() {
501	unless ($MODEL) {	872	unless ($MODEL) {
502	no strict 'refs';	873	no strict 'refs';
		874	local $SIG{__DIE__};
503		875
504	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	876	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
505	my $model = "AnyEvent::Impl::$1";	877	my $model = "AnyEvent::Impl::$1";
506	if (eval "require $model") {	878	if (eval "require $model") {
507	$MODEL = $model;	879	$MODEL = $model;
…		…
537	last;	909	last;
538	}	910	}
539	}	911	}
540		912
541	$MODEL	913	$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.";	914	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
543	}	915	}
544	}	916	}
545		917
546	unshift @ISA, $MODEL;	918	unshift @ISA, $MODEL;
547	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	919	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		920
		921	(shift @post_detect)->() while @post_detect;
548	}	922	}
549		923
550	$MODEL	924	$MODEL
551	}	925	}
552		926
…		…
562	$class->$func (@_);	936	$class->$func (@_);
563	}	937	}
564		938
565	package AnyEvent::Base;	939	package AnyEvent::Base;
566		940
		941	# default implementation for now and time
		942
		943	use Time::HiRes ();
		944
		945	sub time { Time::HiRes::time }
		946	sub now { Time::HiRes::time }
		947
567	# default implementation for ->condvar, ->wait, ->broadcast	948	# default implementation for ->condvar
568		949
569	sub condvar {	950	sub condvar {
570	bless \my $flag, "AnyEvent::Base::CondVar"	951	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	}	952	}
580		953
581	# default implementation for ->signal	954	# default implementation for ->signal
582		955
583	our %SIG_CB;	956	our %SIG_CB;
…		…
636	or Carp::croak "required option 'pid' is missing";	1009	or Carp::croak "required option 'pid' is missing";
637		1010
638	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1011	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
639		1012
640	unless ($WNOHANG) {	1013	unless ($WNOHANG) {
641	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1014	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
642	}	1015	}
643		1016
644	unless ($CHLD_W) {	1017	unless ($CHLD_W) {
645	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1018	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
646	# child could be a zombie already, so make at least one round	1019	# child could be a zombie already, so make at least one round
…		…
656	delete $PID_CB{$pid}{$cb};	1029	delete $PID_CB{$pid}{$cb};
657	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1030	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
658		1031
659	undef $CHLD_W unless keys %PID_CB;	1032	undef $CHLD_W unless keys %PID_CB;
660	}	1033	}
		1034
		1035	package AnyEvent::CondVar;
		1036
		1037	our @ISA = AnyEvent::CondVar::Base::;
		1038
		1039	package AnyEvent::CondVar::Base;
		1040
		1041	use overload
		1042	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1043	fallback => 1;
		1044
		1045	sub _send {
		1046	# nop
		1047	}
		1048
		1049	sub send {
		1050	my $cv = shift;
		1051	$cv->{_ae_sent} = [@_];
		1052	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1053	$cv->_send;
		1054	}
		1055
		1056	sub croak {
		1057	$_[0]{_ae_croak} = $_[1];
		1058	$_[0]->send;
		1059	}
		1060
		1061	sub ready {
		1062	$_[0]{_ae_sent}
		1063	}
		1064
		1065	sub _wait {
		1066	AnyEvent->one_event while !$_[0]{_ae_sent};
		1067	}
		1068
		1069	sub recv {
		1070	$_[0]->_wait;
		1071
		1072	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1073	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1074	}
		1075
		1076	sub cb {
		1077	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1078	$_[0]{_ae_cb}
		1079	}
		1080
		1081	sub begin {
		1082	++$_[0]{_ae_counter};
		1083	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1084	}
		1085
		1086	sub end {
		1087	return if --$_[0]{_ae_counter};
		1088	&{ $_[0]{_ae_end_cb} \|\| sub { $_[0]->send } };
		1089	}
		1090
		1091	# undocumented/compatibility with pre-3.4
		1092	*broadcast = \&send;
		1093	*wait = \&_wait;
661		1094
662	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1095	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
663		1096
664	This is an advanced topic that you do not normally need to use AnyEvent in	1097	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	1098	a module. This section is only of use to event loop authors who want to
…		…
722	model it chooses.	1155	model it chooses.
723		1156
724	=item C<PERL_ANYEVENT_MODEL>	1157	=item C<PERL_ANYEVENT_MODEL>
725		1158
726	This can be used to specify the event model to be used by AnyEvent, before	1159	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	1160	auto detection and -probing kicks in. It must be a string consisting
728	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1161	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,	1162	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	1163	used as event model. If it fails to load AnyEvent will proceed with
731	autodetection and -probing.	1164	auto detection and -probing.
732		1165
733	This functionality might change in future versions.	1166	This functionality might change in future versions.
734		1167
735	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1168	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
736	could start your program like this:	1169	could start your program like this:
737		1170
738	PERL_ANYEVENT_MODEL=Perl perl ...	1171	PERL_ANYEVENT_MODEL=Perl perl ...
		1172
		1173	=item C<PERL_ANYEVENT_PROTOCOLS>
		1174
		1175	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1176	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1177	of auto probing).
		1178
		1179	Must be set to a comma-separated list of protocols or address families,
		1180	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1181	used, and preference will be given to protocols mentioned earlier in the
		1182	list.
		1183
		1184	This variable can effectively be used for denial-of-service attacks
		1185	against local programs (e.g. when setuid), although the impact is likely
		1186	small, as the program has to handle connection errors already-
		1187
		1188	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1189	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1190	- only support IPv4, never try to resolve or contact IPv6
		1191	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1192	IPv6, but prefer IPv6 over IPv4.
		1193
		1194	=item C<PERL_ANYEVENT_EDNS0>
		1195
		1196	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1197	for DNS. This extension is generally useful to reduce DNS traffic, but
		1198	some (broken) firewalls drop such DNS packets, which is why it is off by
		1199	default.
		1200
		1201	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1202	EDNS0 in its DNS requests.
		1203
		1204	=item C<PERL_ANYEVENT_MAX_FORKS>
		1205
		1206	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1207	will create in parallel.
739		1208
740	=back	1209	=back
741		1210
742	=head1 EXAMPLE PROGRAM	1211	=head1 EXAMPLE PROGRAM
743		1212
…		…
754	poll => 'r',	1223	poll => 'r',
755	cb => sub {	1224	cb => sub {
756	warn "io event <$_[0]>\n"; # will always output <r>	1225	warn "io event <$_[0]>\n"; # will always output <r>
757	chomp (my $input = <STDIN>); # read a line	1226	chomp (my $input = <STDIN>); # read a line
758	warn "read: $input\n"; # output what has been read	1227	warn "read: $input\n"; # output what has been read
759	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1228	$cv->send if $input =~ /^q/i; # quit program if /^q/i
760	},	1229	},
761	);	1230	);
762		1231
763	my $time_watcher; # can only be used once	1232	my $time_watcher; # can only be used once
764		1233
…		…
769	});	1238	});
770	}	1239	}
771		1240
772	new_timer; # create first timer	1241	new_timer; # create first timer
773		1242
774	$cv->wait; # wait until user enters /^q/i	1243	$cv->recv; # wait until user enters /^q/i
775		1244
776	=head1 REAL-WORLD EXAMPLE	1245	=head1 REAL-WORLD EXAMPLE
777		1246
778	Consider the L<Net::FCP> module. It features (among others) the following	1247	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:	1248	API calls, which are to freenet what HTTP GET requests are to http:
…		…
829	syswrite $txn->{fh}, $txn->{request}	1298	syswrite $txn->{fh}, $txn->{request}
830	or die "connection or write error";	1299	or die "connection or write error";
831	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1300	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
832		1301
833	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1302	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:	1303	result and signals any possible waiters that the request has finished:
835		1304
836	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1305	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
837		1306
838	if (end-of-file or data complete) {	1307	if (end-of-file or data complete) {
839	$txn->{result} = $txn->{buf};	1308	$txn->{result} = $txn->{buf};
840	$txn->{finished}->broadcast;	1309	$txn->{finished}->send;
841	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1310	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
842	}	1311	}
843		1312
844	The C<result> method, finally, just waits for the finished signal (if the	1313	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	1314	request was already finished, it doesn't wait, of course, and returns the
846	data:	1315	data:
847		1316
848	$txn->{finished}->wait;	1317	$txn->{finished}->recv;
849	return $txn->{result};	1318	return $txn->{result};
850		1319
851	The actual code goes further and collects all errors (C<die>s, exceptions)	1320	The actual code goes further and collects all errors (C<die>s, exceptions)
852	that occured during request processing. The C<result> method detects	1321	that occurred during request processing. The C<result> method detects
853	whether an exception as thrown (it is stored inside the $txn object)	1322	whether an exception as thrown (it is stored inside the $txn object)
854	and just throws the exception, which means connection errors and other	1323	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	1324	problems get reported tot he code that tries to use the result, not in a
856	random callback.	1325	random callback.
857		1326
…		…
888		1357
889	my $quit = AnyEvent->condvar;	1358	my $quit = AnyEvent->condvar;
890		1359
891	$fcp->txn_client_get ($url)->cb (sub {	1360	$fcp->txn_client_get ($url)->cb (sub {
892	...	1361	...
893	$quit->broadcast;	1362	$quit->send;
894	});	1363	});
895		1364
896	$quit->wait;	1365	$quit->recv;
897		1366
898		1367
899	=head1 BENCHMARKS	1368	=head1 BENCHMARKS
900		1369
901	To give you an idea of the performance and overheads that AnyEvent adds	1370	To give you an idea of the performance and overheads that AnyEvent adds
…		…
903	of various event loops I prepared some benchmarks.	1372	of various event loops I prepared some benchmarks.
904		1373
905	=head2 BENCHMARKING ANYEVENT OVERHEAD	1374	=head2 BENCHMARKING ANYEVENT OVERHEAD
906		1375
907	Here is a benchmark of various supported event models used natively and	1376	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	1377	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,	1378	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.	1379	which it is), lets them fire exactly once and destroys them again.
911		1380
912	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1381	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
913	distribution.	1382	distribution.
…		…
930	all watchers, to avoid adding memory overhead. That means closure creation	1399	all watchers, to avoid adding memory overhead. That means closure creation
931	and memory usage is not included in the figures.	1400	and memory usage is not included in the figures.
932		1401
933	I<invoke> is the time, in microseconds, used to invoke a simple	1402	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	1403	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	1404	invoked "watcher" times, it would C<< ->send >> a condvar once to
936	signal the end of this phase.	1405	signal the end of this phase.
937		1406
938	I<destroy> is the time, in microseconds, that it takes to destroy a single	1407	I<destroy> is the time, in microseconds, that it takes to destroy a single
939	watcher.	1408	watcher.
940		1409
…		…
944	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1413	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	1414	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	1415	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	1416	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	1417	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	1418	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	1419	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	1420	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	1421	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	1422	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select
954		1423
…		…
1000	file descriptor is dup()ed for each watcher. This shows that the dup()	1469	file descriptor is dup()ed for each watcher. This shows that the dup()
1001	employed by some adaptors is not a big performance issue (it does incur a	1470	employed by some adaptors is not a big performance issue (it does incur a
1002	hidden memory cost inside the kernel which is not reflected in the figures	1471	hidden memory cost inside the kernel which is not reflected in the figures
1003	above).	1472	above).
1004		1473
1005	C<POE>, regardless of underlying event loop (whether using its pure	1474	C<POE>, regardless of underlying event loop (whether using its pure perl
1006	perl select-based backend or the Event module, the POE-EV backend	1475	select-based backend or the Event module, the POE-EV backend couldn't
1007	couldn't be tested because it wasn't working) shows abysmal performance	1476	be tested because it wasn't working) shows abysmal performance and
1008	and memory usage: Watchers use almost 30 times as much memory as	1477	memory usage with AnyEvent: Watchers use almost 30 times as much memory
1009	EV watchers, and 10 times as much memory as Event (the high memory	1478	as EV watchers, and 10 times as much memory as Event (the high memory
1010	requirements are caused by requiring a session for each watcher). Watcher	1479	requirements are caused by requiring a session for each watcher). Watcher
1011	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1480	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1481	implementation.
		1482
1012	implementation. The design of the POE adaptor class in AnyEvent can not	1483	The design of the POE adaptor class in AnyEvent can not really account
1013	really account for this, as session creation overhead is small compared	1484	for the performance issues, though, as session creation overhead is
1014	to execution of the state machine, which is coded pretty optimally within	1485	small compared to execution of the state machine, which is coded pretty
1015	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1486	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1487	using multiple sessions is not a good approach, especially regarding
		1488	memory usage, even the author of POE could not come up with a faster
		1489	design).
1016		1490
1017	=head3 Summary	1491	=head3 Summary
1018		1492
1019	=over 4	1493	=over 4
1020		1494
…		…
1031		1505
1032	=back	1506	=back
1033		1507
1034	=head2 BENCHMARKING THE LARGE SERVER CASE	1508	=head2 BENCHMARKING THE LARGE SERVER CASE
1035		1509
1036	This benchmark atcually benchmarks the event loop itself. It works by	1510	This benchmark actually benchmarks the event loop itself. It works by
1037	creating a number of "servers": each server consists of a socketpair, a	1511	creating a number of "servers": each server consists of a socket pair, a
1038	timeout watcher that gets reset on activity (but never fires), and an I/O	1512	timeout watcher that gets reset on activity (but never fires), and an I/O
1039	watcher waiting for input on one side of the socket. Each time the socket	1513	watcher waiting for input on one side of the socket. Each time the socket
1040	watcher reads a byte it will write that byte to a random other "server".	1514	watcher reads a byte it will write that byte to a random other "server".
1041		1515
1042	The effect is that there will be a lot of I/O watchers, only part of which	1516	The effect is that there will be a lot of I/O watchers, only part of which
1043	are active at any one point (so there is a constant number of active	1517	are active at any one point (so there is a constant number of active
1044	fds for each loop iterstaion, but which fds these are is random). The	1518	fds for each loop iteration, but which fds these are is random). The
1045	timeout is reset each time something is read because that reflects how	1519	timeout is reset each time something is read because that reflects how
1046	most timeouts work (and puts extra pressure on the event loops).	1520	most timeouts work (and puts extra pressure on the event loops).
1047		1521
1048	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1522	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1049	(1%) are active. This mirrors the activity of large servers with many	1523	(1%) are active. This mirrors the activity of large servers with many
1050	connections, most of which are idle at any one point in time.	1524	connections, most of which are idle at any one point in time.
1051		1525
1052	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1526	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1053	distribution.	1527	distribution.
…		…
1055	=head3 Explanation of the columns	1529	=head3 Explanation of the columns
1056		1530
1057	I<sockets> is the number of sockets, and twice the number of "servers" (as	1531	I<sockets> is the number of sockets, and twice the number of "servers" (as
1058	each server has a read and write socket end).	1532	each server has a read and write socket end).
1059		1533
1060	I<create> is the time it takes to create a socketpair (which is	1534	I<create> is the time it takes to create a socket pair (which is
1061	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1535	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1062		1536
1063	I<request>, the most important value, is the time it takes to handle a	1537	I<request>, the most important value, is the time it takes to handle a
1064	single "request", that is, reading the token from the pipe and forwarding	1538	single "request", that is, reading the token from the pipe and forwarding
1065	it to another server. This includes deleting the old timeout and creating	1539	it to another server. This includes deleting the old timeout and creating
…		…
1067		1541
1068	=head3 Results	1542	=head3 Results
1069		1543
1070	name sockets create request	1544	name sockets create request
1071	EV 20000 69.01 11.16	1545	EV 20000 69.01 11.16
1072	Perl 20000 75.28 112.76	1546	Perl 20000 73.32 35.87
1073	Event 20000 212.62 257.32	1547	Event 20000 212.62 257.32
1074	Glib 20000 651.16 1896.30	1548	Glib 20000 651.16 1896.30
1075	POE 20000 349.67 12317.24 uses POE::Loop::Event	1549	POE 20000 349.67 12317.24 uses POE::Loop::Event
1076		1550
1077	=head3 Discussion	1551	=head3 Discussion
…		…
1099		1573
1100	=head3 Summary	1574	=head3 Summary
1101		1575
1102	=over 4	1576	=over 4
1103		1577
1104	=item * The pure perl implementation performs extremely well, considering	1578	=item * The pure perl implementation performs extremely well.
1105	that it uses select.
1106		1579
1107	=item * Avoid Glib or POE in large projects where performance matters.	1580	=item * Avoid Glib or POE in large projects where performance matters.
1108		1581
1109	=back	1582	=back
1110		1583
…		…
1123		1596
1124	=head3 Results	1597	=head3 Results
1125		1598
1126	name sockets create request	1599	name sockets create request
1127	EV 16 20.00 6.54	1600	EV 16 20.00 6.54
		1601	Perl 16 25.75 12.62
1128	Event 16 81.27 35.86	1602	Event 16 81.27 35.86
1129	Glib 16 32.63 15.48	1603	Glib 16 32.63 15.48
1130	Perl 16 24.62 162.37
1131	POE 16 261.87 276.28 uses POE::Loop::Event	1604	POE 16 261.87 276.28 uses POE::Loop::Event
1132		1605
1133	=head3 Discussion	1606	=head3 Discussion
1134		1607
1135	The benchmark tries to test the performance of a typical small	1608	The benchmark tries to test the performance of a typical small
1136	server. While knowing how various event loops perform is interesting, keep	1609	server. While knowing how various event loops perform is interesting, keep
1137	in mind that their overhead in this case is usually not as important, due	1610	in mind that their overhead in this case is usually not as important, due
1138	to the small absolute number of watchers.	1611	to the small absolute number of watchers (that is, you need efficiency and
		1612	speed most when you have lots of watchers, not when you only have a few of
		1613	them).
1139		1614
1140	EV is again fastest.	1615	EV is again fastest.
1141		1616
1142	The C-based event loops Event and Glib come in second this time, as the	1617	Perl again comes second. It is noticeably faster than the C-based event
1143	overhead of running an iteration is much smaller in C than in Perl (little	1618	loops Event and Glib, although the difference is too small to really
1144	code to execute in the inner loop, and perl's function calling overhead is	1619	matter.
1145	high, and updating all the data structures is costly).
1146		1620
1147	The pure perl event loop is much slower, but still competitive.
1148
1149	POE also performs much better in this case, but is is stillf ar behind the	1621	POE also performs much better in this case, but is is still far behind the
1150	others.	1622	others.
1151		1623
1152	=head3 Summary	1624	=head3 Summary
1153		1625
1154	=over 4	1626	=over 4
…		…
1160		1632
1161		1633
1162	=head1 FORK	1634	=head1 FORK
1163		1635
1164	Most event libraries are not fork-safe. The ones who are usually are	1636	Most event libraries are not fork-safe. The ones who are usually are
1165	because they are so inefficient. Only L<EV> is fully fork-aware.	1637	because they rely on inefficient but fork-safe C<select> or C<poll>
		1638	calls. Only L<EV> is fully fork-aware.
1166		1639
1167	If you have to fork, you must either do so I<before> creating your first	1640	If you have to fork, you must either do so I<before> creating your first
1168	watcher OR you must not use AnyEvent at all in the child.	1641	watcher OR you must not use AnyEvent at all in the child.
1169		1642
1170		1643
…		…
1182		1655
1183	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1656	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1184		1657
1185	use AnyEvent;	1658	use AnyEvent;
1186		1659
		1660	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1661	be used to probe what backend is used and gain other information (which is
		1662	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
		1663
1187		1664
1188	=head1 SEE ALSO	1665	=head1 SEE ALSO
1189		1666
1190	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1667	Utility functions: L<AnyEvent::Util>.
1191	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1668
		1669	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1192	L<Event::Lib>, L<Qt>, L<POE>.	1670	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1193		1671
1194	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1672	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1195	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1673	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1196	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1674	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1197	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1675	L<AnyEvent::Impl::POE>.
1198		1676
		1677	Non-blocking file handles, sockets, TCP clients and
		1678	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1679
		1680	Asynchronous DNS: L<AnyEvent::DNS>.
		1681
		1682	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1683
1199	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1684	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1200		1685
1201		1686
1202	=head1 AUTHOR	1687	=head1 AUTHOR
1203		1688
1204	Marc Lehmann <schmorp@schmorp.de>	1689	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.96 by root, Sat Apr 26 11:16:16 2008 UTC vs. Revision 1.147 by root, Fri May 30 21:43:26 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.96 by root, Sat Apr 26 11:16:16 2008 UTC vs.
Revision 1.147 by root, Fri May 30 21:43:26 2008 UTC