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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.102 by root, Sun Apr 27 21:16:26 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		76
71	=head1 DESCRIPTION	77	=head1 DESCRIPTION
72		78
…		…
78	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>
79	module.	85	module.
80		86
81	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
82	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
83	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	89	following modules is already loaded: L<EV>,
84	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>,
85	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
86	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
87	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
88	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
…		…
102	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
103	use AnyEvent so their modules work together with others seamlessly...	109	use AnyEvent so their modules work together with others seamlessly...
104		110
105	The pure-perl implementation of AnyEvent is called	111	The pure-perl implementation of AnyEvent is called
106	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
107	explicitly.	113	explicitly and enjoy the high availability of that event loop :)
108		114
109	=head1 WATCHERS	115	=head1 WATCHERS
110		116
111	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
112	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
113	the callback to call, the filehandle to watch, etc.	119	the callback to call, the file handle to watch, etc.
114		120
115	These watchers are normal Perl objects with normal Perl lifetime. After	121	These watchers are normal Perl objects with normal Perl lifetime. After
116	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
117	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
118	is in control).	124	is in control).
…		…
227	timers.	233	timers.
228		234
229	AnyEvent always prefers relative timers, if available, matching the	235	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	236	AnyEvent API.
231		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
232	=head2 SIGNAL WATCHERS	293	=head2 SIGNAL WATCHERS
233		294
234	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
235	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
236	be invoked whenever a signal occurs.	297	be invoked whenever a signal occurs.
237		298
238	Although the callback might get passed parameters, their value and	299	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	300	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	301	callbacks cannot use arguments passed to signal watcher callbacks.
241		302
242	Multiple signal occurances can be clumped together into one callback	303	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	304	invocation, and callback invocation will be synchronous. Synchronous means
244	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,
245	but it is guarenteed not to interrupt any other callbacks.	306	but it is guaranteed not to interrupt any other callbacks.
246		307
247	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
248	between multiple watchers.	309	between multiple watchers.
249		310
250	This watcher might use C<%SIG>, so programs overwriting those signals	311	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
279		340
280	Example: fork a process and wait for it	341	Example: fork a process and wait for it
281		342
282	my $done = AnyEvent->condvar;	343	my $done = AnyEvent->condvar;
283		344
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	345	my $pid = fork or exit 5;
287		346
288	my $w = AnyEvent->child (	347	my $w = AnyEvent->child (
289	pid => $pid,	348	pid => $pid,
290	cb => sub {	349	cb => sub {
291	my ($pid, $status) = @_;	350	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	351	warn "pid $pid exited with status $status";
293	$done->broadcast;	352	$done->send;
294	},	353	},
295	);	354	);
296		355
297	# do something else, then wait for process exit	356	# do something else, then wait for process exit
298	$done->wait;	357	$done->recv;
299		358
300	=head2 CONDITION VARIABLES	359	=head2 CONDITION VARIABLES
301		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
302	Condition variables can be created by calling the C<< AnyEvent->condvar >>	371	Condition variables can be created by calling the C<< AnyEvent->condvar
303	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.
304		375
305	A condition variable waits for a condition - precisely that the C<<	376	After creation, the condition variable is "false" until it becomes "true"
306	->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).
307		380
308	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,
309	example, if you write a module that does asynchronous http requests,	389	for example, if you write a module that does asynchronous http requests,
310	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
311	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.
312		393
313	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,
314	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
315	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
316	->broadcast >> the "quit" event.	397	button of your app, which would C<< ->send >> the "quit" event.
317		398
318	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
319	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
320	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
321	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,
322	as this asks for trouble.	403	as this asks for trouble.
323		404
324	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.
325		446
326	=over 4	447	=over 4
327		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
328	=item $cv->wait	480	=item $cv->end
329		481
330	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 $cv->recv
		539
		540	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
331	called on c<$cv>, while servicing other watchers normally.	541	>> methods have been called on c<$cv>, while servicing other watchers
		542	normally.
332		543
333	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
334	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.
335		552
336	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
337	(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
338	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
339	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
340	condition variables with some kind of request results and supporting	557	condition variables with some kind of request results and supporting
341	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,
342	while still suppporting blocking waits if the caller so desires).	559	while still supporting blocking waits if the caller so desires).
343		560
344	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
345	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
346	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	563	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
347	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	564	can supply.
348	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
349	from different coroutines, however).
350		565
351	=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).
352		571
353	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
354	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
355	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.
356		590
357	=back	591	=back
358
359	Example:
360
361	# wait till the result is ready
362	my $result_ready = AnyEvent->condvar;
363
364	# do something such as adding a timer
365	# or socket watcher the calls $result_ready->broadcast
366	# when the "result" is ready.
367	# in this case, we simply use a timer:
368	my $w = AnyEvent->timer (
369	after => 1,
370	cb => sub { $result_ready->broadcast },
371	);
372
373	# this "blocks" (while handling events) till the watcher
374	# calls broadcast
375	$result_ready->wait;
376		592
377	=head1 GLOBAL VARIABLES AND FUNCTIONS	593	=head1 GLOBAL VARIABLES AND FUNCTIONS
378		594
379	=over 4	595	=over 4
380		596
…		…
386	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	602	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
387	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	603	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
388		604
389	The known classes so far are:	605	The known classes so far are:
390		606
391	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
392	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
393	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	607	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
394	AnyEvent::Impl::Event based on Event, second best choice.	608	AnyEvent::Impl::Event based on Event, second best choice.
		609	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
395	AnyEvent::Impl::Glib based on Glib, third-best choice.	610	AnyEvent::Impl::Glib based on Glib, third-best choice.
396	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
397	AnyEvent::Impl::Tk based on Tk, very bad choice.	611	AnyEvent::Impl::Tk based on Tk, very bad choice.
398	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	612	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
399	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	613	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
400	AnyEvent::Impl::POE based on POE, not generic enough for full support.	614	AnyEvent::Impl::POE based on POE, not generic enough for full support.
401		615
…		…
414	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	628	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
415	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
416	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
417	runtime.	631	runtime.
418		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
419	=back	654	=back
420		655
421	=head1 WHAT TO DO IN A MODULE	656	=head1 WHAT TO DO IN A MODULE
422		657
423	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
…		…
426	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
427	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
428	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
429	to load the event module first.	664	to load the event module first.
430		665
431	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
432	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
433	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
434	events is to stay interactive.	669	events is to stay interactive.
435		670
436	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
437	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
438	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 >>
439	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).
440		675
441	=head1 WHAT TO DO IN THE MAIN PROGRAM	676	=head1 WHAT TO DO IN THE MAIN PROGRAM
442		677
443	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
…		…
445		680
446	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
447	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
448	decide which implementation to chose if some module relies on it.	683	decide which implementation to chose if some module relies on it.
449		684
450	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
451	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
452	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
453	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
454	modules might create watchers when they are loaded, and AnyEvent will	689	modules might create watchers when they are loaded, and AnyEvent will
455	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
456	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.
457		692
458	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
459	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	694	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
460	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
461		713
462	=head1 OTHER MODULES	714	=head1 OTHER MODULES
463		715
464	The following is a non-exhaustive list of additional modules that use	716	The following is a non-exhaustive list of additional modules that use
465	AnyEvent and can therefore be mixed easily with other AnyEvent modules	717	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
477		729
478	Provide read and write buffers and manages watchers for reads and writes.	730	Provide read and write buffers and manages watchers for reads and writes.
479		731
480	=item L<AnyEvent::Socket>	732	=item L<AnyEvent::Socket>
481		733
482	Provides a means to do non-blocking connects, accepts etc.	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.
483		741
484	=item L<AnyEvent::HTTPD>	742	=item L<AnyEvent::HTTPD>
485		743
486	Provides a simple web application server framework.	744	Provides a simple web application server framework.
487
488	=item L<AnyEvent::DNS>
489
490	Provides asynchronous DNS resolver capabilities, beyond what
491	L<AnyEvent::Util> offers.
492		745
493	=item L<AnyEvent::FastPing>	746	=item L<AnyEvent::FastPing>
494		747
495	The fastest ping in the west.	748	The fastest ping in the west.
496		749
…		…
511		764
512	High level API for event-based execution flow control.	765	High level API for event-based execution flow control.
513		766
514	=item L<Coro>	767	=item L<Coro>
515		768
516	Has special support for AnyEvent.	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.
517		781
518	=item L<IO::Lambda>	782	=item L<IO::Lambda>
519		783
520	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	784	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
521
522	=item L<IO::AIO>
523
524	Truly asynchronous I/O, should be in the toolbox of every event
525	programmer. Can be trivially made to use AnyEvent.
526
527	=item L<BDB>
528
529	Truly asynchronous Berkeley DB access. Can be trivially made to use
530	AnyEvent.
531		785
532	=back	786	=back
533		787
534	=cut	788	=cut
535		789
…		…
538	no warnings;	792	no warnings;
539	use strict;	793	use strict;
540		794
541	use Carp;	795	use Carp;
542		796
543	our $VERSION = '3.3';	797	our $VERSION = '4.05';
544	our $MODEL;	798	our $MODEL;
545		799
546	our $AUTOLOAD;	800	our $AUTOLOAD;
547	our @ISA;	801	our @ISA;
548		802
		803	our @REGISTRY;
		804
		805	our $WIN32;
		806
		807	BEGIN {
		808	my $win32 = ! ! ($^O =~ /mswin32/i);
		809	eval "sub WIN32(){ $win32 }";
		810	}
		811
549	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	812	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
550		813
551	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	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		821	}
552		822
553	my @models = (	823	my @models = (
554	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
555	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
556	[EV:: => AnyEvent::Impl::EV::],	824	[EV:: => AnyEvent::Impl::EV::],
557	[Event:: => AnyEvent::Impl::Event::],	825	[Event:: => AnyEvent::Impl::Event::],
558	[Glib:: => AnyEvent::Impl::Glib::],
559	[Tk:: => AnyEvent::Impl::Tk::],
560	[Wx:: => AnyEvent::Impl::POE::],
561	[Prima:: => AnyEvent::Impl::POE::],
562	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	826	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
563	# everything below here will not be autoprobed as the pureperl backend should work everywhere	827	# everything below here will not be autoprobed
		828	# as the pureperl backend should work everywhere
		829	# and is usually faster
		830	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		831	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
564	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	832	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
565	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	833	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
566	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	834	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		835	[Wx:: => AnyEvent::Impl::POE::],
		836	[Prima:: => AnyEvent::Impl::POE::],
567	);	837	);
568		838
569	our %method = map +($_ => 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	}
570		862
571	sub detect() {	863	sub detect() {
572	unless ($MODEL) {	864	unless ($MODEL) {
573	no strict 'refs';	865	no strict 'refs';
		866	local $SIG{__DIE__};
574		867
575	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	868	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
576	my $model = "AnyEvent::Impl::$1";	869	my $model = "AnyEvent::Impl::$1";
577	if (eval "require $model") {	870	if (eval "require $model") {
578	$MODEL = $model;	871	$MODEL = $model;
…		…
608	last;	901	last;
609	}	902	}
610	}	903	}
611		904
612	$MODEL	905	$MODEL
613	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.";
614	}	907	}
615	}	908	}
616		909
617	unshift @ISA, $MODEL;	910	unshift @ISA, $MODEL;
618	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	911	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		912
		913	(shift @post_detect)->() while @post_detect;
619	}	914	}
620		915
621	$MODEL	916	$MODEL
622	}	917	}
623		918
…		…
633	$class->$func (@_);	928	$class->$func (@_);
634	}	929	}
635		930
636	package AnyEvent::Base;	931	package AnyEvent::Base;
637		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
638	# default implementation for ->condvar, ->wait, ->broadcast	940	# default implementation for ->condvar
639		941
640	sub condvar {	942	sub condvar {
641	bless \my $flag, "AnyEvent::Base::CondVar"	943	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
642	}
643
644	sub AnyEvent::Base::CondVar::broadcast {
645	${$_[0]}++;
646	}
647
648	sub AnyEvent::Base::CondVar::wait {
649	AnyEvent->one_event while !${$_[0]};
650	}	944	}
651		945
652	# default implementation for ->signal	946	# default implementation for ->signal
653		947
654	our %SIG_CB;	948	our %SIG_CB;
…		…
707	or Carp::croak "required option 'pid' is missing";	1001	or Carp::croak "required option 'pid' is missing";
708		1002
709	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1003	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
710		1004
711	unless ($WNOHANG) {	1005	unless ($WNOHANG) {
712	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1006	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
713	}	1007	}
714		1008
715	unless ($CHLD_W) {	1009	unless ($CHLD_W) {
716	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1010	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
717	# 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
…		…
727	delete $PID_CB{$pid}{$cb};	1021	delete $PID_CB{$pid}{$cb};
728	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1022	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
729		1023
730	undef $CHLD_W unless keys %PID_CB;	1024	undef $CHLD_W unless keys %PID_CB;
731	}	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;
732		1086
733	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1087	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
734		1088
735	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
736	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
…		…
793	model it chooses.	1147	model it chooses.
794		1148
795	=item C<PERL_ANYEVENT_MODEL>	1149	=item C<PERL_ANYEVENT_MODEL>
796		1150
797	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
798	autodetection and -probing kicks in. It must be a string consisting	1152	auto detection and -probing kicks in. It must be a string consisting
799	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1153	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
800	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,
801	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
802	autodetection and -probing.	1156	auto detection and -probing.
803		1157
804	This functionality might change in future versions.	1158	This functionality might change in future versions.
805		1159
806	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
807	could start your program like this:	1161	could start your program like this:
808		1162
809	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.
810		1200
811	=back	1201	=back
812		1202
813	=head1 EXAMPLE PROGRAM	1203	=head1 EXAMPLE PROGRAM
814		1204
…		…
825	poll => 'r',	1215	poll => 'r',
826	cb => sub {	1216	cb => sub {
827	warn "io event <$_[0]>\n"; # will always output <r>	1217	warn "io event <$_[0]>\n"; # will always output <r>
828	chomp (my $input = <STDIN>); # read a line	1218	chomp (my $input = <STDIN>); # read a line
829	warn "read: $input\n"; # output what has been read	1219	warn "read: $input\n"; # output what has been read
830	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1220	$cv->send if $input =~ /^q/i; # quit program if /^q/i
831	},	1221	},
832	);	1222	);
833		1223
834	my $time_watcher; # can only be used once	1224	my $time_watcher; # can only be used once
835		1225
…		…
840	});	1230	});
841	}	1231	}
842		1232
843	new_timer; # create first timer	1233	new_timer; # create first timer
844		1234
845	$cv->wait; # wait until user enters /^q/i	1235	$cv->recv; # wait until user enters /^q/i
846		1236
847	=head1 REAL-WORLD EXAMPLE	1237	=head1 REAL-WORLD EXAMPLE
848		1238
849	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
850	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:
…		…
900	syswrite $txn->{fh}, $txn->{request}	1290	syswrite $txn->{fh}, $txn->{request}
901	or die "connection or write error";	1291	or die "connection or write error";
902	$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 });
903		1293
904	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
905	result and signals any possible waiters that the request ahs finished:	1295	result and signals any possible waiters that the request has finished:
906		1296
907	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1297	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
908		1298
909	if (end-of-file or data complete) {	1299	if (end-of-file or data complete) {
910	$txn->{result} = $txn->{buf};	1300	$txn->{result} = $txn->{buf};
911	$txn->{finished}->broadcast;	1301	$txn->{finished}->send;
912	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1302	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
913	}	1303	}
914		1304
915	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
916	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
917	data:	1307	data:
918		1308
919	$txn->{finished}->wait;	1309	$txn->{finished}->recv;
920	return $txn->{result};	1310	return $txn->{result};
921		1311
922	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)
923	that occured during request processing. The C<result> method detects	1313	that occurred during request processing. The C<result> method detects
924	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)
925	and just throws the exception, which means connection errors and other	1315	and just throws the exception, which means connection errors and other
926	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
927	random callback.	1317	random callback.
928		1318
…		…
959		1349
960	my $quit = AnyEvent->condvar;	1350	my $quit = AnyEvent->condvar;
961		1351
962	$fcp->txn_client_get ($url)->cb (sub {	1352	$fcp->txn_client_get ($url)->cb (sub {
963	...	1353	...
964	$quit->broadcast;	1354	$quit->send;
965	});	1355	});
966		1356
967	$quit->wait;	1357	$quit->recv;
968		1358
969		1359
970	=head1 BENCHMARKS	1360	=head1 BENCHMARKS
971		1361
972	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
…		…
974	of various event loops I prepared some benchmarks.	1364	of various event loops I prepared some benchmarks.
975		1365
976	=head2 BENCHMARKING ANYEVENT OVERHEAD	1366	=head2 BENCHMARKING ANYEVENT OVERHEAD
977		1367
978	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
979	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
980	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,
981	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.
982		1372
983	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
984	distribution.	1374	distribution.
…		…
1001	all watchers, to avoid adding memory overhead. That means closure creation	1391	all watchers, to avoid adding memory overhead. That means closure creation
1002	and memory usage is not included in the figures.	1392	and memory usage is not included in the figures.
1003		1393
1004	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
1005	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
1006	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1396	invoked "watcher" times, it would C<< ->send >> a condvar once to
1007	signal the end of this phase.	1397	signal the end of this phase.
1008		1398
1009	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
1010	watcher.	1400	watcher.
1011		1401
…		…
1071	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()
1072	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
1073	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
1074	above).	1464	above).
1075		1465
1076	C<POE>, regardless of underlying event loop (whether using its pure	1466	C<POE>, regardless of underlying event loop (whether using its pure perl
1077	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
1078	couldn't be tested because it wasn't working) shows abysmal performance	1468	be tested because it wasn't working) shows abysmal performance and
1079	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
1080	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
1081	requirements are caused by requiring a session for each watcher). Watcher	1471	requirements are caused by requiring a session for each watcher). Watcher
1082	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
1083	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
1084	really account for this, as session creation overhead is small compared	1476	for the performance issues, though, as session creation overhead is
1085	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
1086	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).
1087		1482
1088	=head3 Summary	1483	=head3 Summary
1089		1484
1090	=over 4	1485	=over 4
1091		1486
…		…
1102		1497
1103	=back	1498	=back
1104		1499
1105	=head2 BENCHMARKING THE LARGE SERVER CASE	1500	=head2 BENCHMARKING THE LARGE SERVER CASE
1106		1501
1107	This benchmark atcually benchmarks the event loop itself. It works by	1502	This benchmark actually benchmarks the event loop itself. It works by
1108	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
1109	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
1110	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
1111	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".
1112		1507
1113	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
1114	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
1115	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
1116	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
1117	most timeouts work (and puts extra pressure on the event loops).	1512	most timeouts work (and puts extra pressure on the event loops).
1118		1513
1119	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
1120	(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
1121	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.
1122		1517
1123	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
1124	distribution.	1519	distribution.
…		…
1126	=head3 Explanation of the columns	1521	=head3 Explanation of the columns
1127		1522
1128	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
1129	each server has a read and write socket end).	1524	each server has a read and write socket end).
1130		1525
1131	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
1132	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.
1133		1528
1134	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
1135	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
1136	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
…		…
1170		1565
1171	=head3 Summary	1566	=head3 Summary
1172		1567
1173	=over 4	1568	=over 4
1174		1569
1175	=item * The pure perl implementation performs extremely well, considering	1570	=item * The pure perl implementation performs extremely well.
1176	that it uses select.
1177		1571
1178	=item * Avoid Glib or POE in large projects where performance matters.	1572	=item * Avoid Glib or POE in large projects where performance matters.
1179		1573
1180	=back	1574	=back
1181		1575
…		…
1210	speed most when you have lots of watchers, not when you only have a few of	1604	speed most when you have lots of watchers, not when you only have a few of
1211	them).	1605	them).
1212		1606
1213	EV is again fastest.	1607	EV is again fastest.
1214		1608
1215	Perl again comes second. It is noticably faster than the C-based event	1609	Perl again comes second. It is noticeably faster than the C-based event
1216	loops Event and Glib, although the difference is too small to really	1610	loops Event and Glib, although the difference is too small to really
1217	matter.	1611	matter.
1218		1612
1219	POE also performs much better in this case, but is is still far behind the	1613	POE also performs much better in this case, but is is still far behind the
1220	others.	1614	others.
…		…
1230		1624
1231		1625
1232	=head1 FORK	1626	=head1 FORK
1233		1627
1234	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
1235	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.
1236		1631
1237	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
1238	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.
1239		1634
1240		1635
…		…
1252		1647
1253	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1648	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1254		1649
1255	use AnyEvent;	1650	use AnyEvent;
1256		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
1257		1656
1258	=head1 SEE ALSO	1657	=head1 SEE ALSO
1259		1658
1260	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1659	Utility functions: L<AnyEvent::Util>.
1261	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>,
1262	L<Event::Lib>, L<Qt>, L<POE>.	1662	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1263		1663
1264	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1664	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1265	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>,
1266	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1666	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1267	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1667	L<AnyEvent::Impl::POE>.
1268		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
1269	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1676	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1270		1677
1271		1678
1272	=head1 AUTHOR	1679	=head1 AUTHOR
1273		1680
1274	Marc Lehmann <schmorp@schmorp.de>	1681	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.102 by root, Sun Apr 27 21:16:26 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 1.102 by root, Sun Apr 27 21:16:26 2008 UTC vs.
Revision 1.143 by root, Wed May 28 23:57:38 2008 UTC