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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.90 by root, Fri Apr 25 14:24:29 2008 UTC vs.
Revision 1.152 by root, Tue Jun 3 09:02:46 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
		23	=head1 INTRODUCTION/TUTORIAL
		24
		25	This manpage is mainly a reference manual. If you are interested
		26	in a tutorial or some gentle introduction, have a look at the
		27	L<AnyEvent::Intro> manpage.
22		28
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	29	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		30
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	31	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	32	nowadays. So what is different about AnyEvent?
…		…
48	isn't itself. What's worse, all the potential users of your module are	54	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.	55	I<also> forced to use the same event loop you use.
50		56
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	58	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	59	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,	60	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	61	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	62	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	63	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).	64	event loops to AnyEvent, too, so it is future-proof).
59		65
60	In addition to being free of having to use I<the one and only true event	66	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	67	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	68	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	69	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	70	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	71	technically possible.
66		72
		73	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		74	of useful functionality, such as an asynchronous DNS resolver, 100%
		75	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		76	such as Windows) and lots of real-world knowledge and workarounds for
		77	platform bugs and differences.
		78
67	Of course, if you want lots of policy (this can arguably be somewhat	79	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	80	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	81	model, you should I<not> use this module.
70
71		82
72	=head1 DESCRIPTION	83	=head1 DESCRIPTION
73		84
74	L<AnyEvent> provides an identical interface to multiple event loops. This	85	L<AnyEvent> provides an identical interface to multiple event loops. This
75	allows module authors to utilise an event loop without forcing module	86	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>	90	The interface itself is vaguely similar, but not identical to the L<Event>
80	module.	91	module.
81		92
82	During the first call of any watcher-creation method, the module tries	93	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	94	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>,	95	following modules is already loaded: L<EV>,
85	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	96	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	97	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	98	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	99	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	100	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	114	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...	115	use AnyEvent so their modules work together with others seamlessly...
105		116
106	The pure-perl implementation of AnyEvent is called	117	The pure-perl implementation of AnyEvent is called
107	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	118	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
108	explicitly.	119	explicitly and enjoy the high availability of that event loop :)
109		120
110	=head1 WATCHERS	121	=head1 WATCHERS
111		122
112	AnyEvent has the central concept of a I<watcher>, which is an object that	123	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	124	stores relevant data for each kind of event you are waiting for, such as
114	the callback to call, the filehandle to watch, etc.	125	the callback to call, the file handle to watch, etc.
115		126
116	These watchers are normal Perl objects with normal Perl lifetime. After	127	These watchers are normal Perl objects with normal Perl lifetime. After
117	creating a watcher it will immediately "watch" for events and invoke the	128	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	129	callback when the event occurs (of course, only when the event model
119	is in control).	130	is in control).
…		…
127	Many watchers either are used with "recursion" (repeating timers for	138	Many watchers either are used with "recursion" (repeating timers for
128	example), or need to refer to their watcher object in other ways.	139	example), or need to refer to their watcher object in other ways.
129		140
130	An any way to achieve that is this pattern:	141	An any way to achieve that is this pattern:
131		142
132	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	143	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
133	# you can use $w here, for example to undef it	144	# you can use $w here, for example to undef it
134	undef $w;	145	undef $w;
135	});	146	});
136		147
137	Note that C<my $w; $w => combination. This is necessary because in Perl,	148	Note that C<my $w; $w => combination. This is necessary because in Perl,
138	my variables are only visible after the statement in which they are	149	my variables are only visible after the statement in which they are
139	declared.	150	declared.
140		151
…		…
228	timers.	239	timers.
229		240
230	AnyEvent always prefers relative timers, if available, matching the	241	AnyEvent always prefers relative timers, if available, matching the
231	AnyEvent API.	242	AnyEvent API.
232		243
		244	AnyEvent has two additional methods that return the "current time":
		245
		246	=over 4
		247
		248	=item AnyEvent->time
		249
		250	This returns the "current wallclock time" as a fractional number of
		251	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		252	return, and the result is guaranteed to be compatible with those).
		253
		254	It progresses independently of any event loop processing, i.e. each call
		255	will check the system clock, which usually gets updated frequently.
		256
		257	=item AnyEvent->now
		258
		259	This also returns the "current wallclock time", but unlike C<time>, above,
		260	this value might change only once per event loop iteration, depending on
		261	the event loop (most return the same time as C<time>, above). This is the
		262	time that AnyEvent's timers get scheduled against.
		263
		264	I<In almost all cases (in all cases if you don't care), this is the
		265	function to call when you want to know the current time.>
		266
		267	This function is also often faster then C<< AnyEvent->time >>, and
		268	thus the preferred method if you want some timestamp (for example,
		269	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		270
		271	The rest of this section is only of relevance if you try to be very exact
		272	with your timing, you can skip it without bad conscience.
		273
		274	For a practical example of when these times differ, consider L<Event::Lib>
		275	and L<EV> and the following set-up:
		276
		277	The event loop is running and has just invoked one of your callback at
		278	time=500 (assume no other callbacks delay processing). In your callback,
		279	you wait a second by executing C<sleep 1> (blocking the process for a
		280	second) and then (at time=501) you create a relative timer that fires
		281	after three seconds.
		282
		283	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		284	both return C<501>, because that is the current time, and the timer will
		285	be scheduled to fire at time=504 (C<501> + C<3>).
		286
		287	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		288	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		289	last event processing phase started. With L<EV>, your timer gets scheduled
		290	to run at time=503 (C<500> + C<3>).
		291
		292	In one sense, L<Event::Lib> is more exact, as it uses the current time
		293	regardless of any delays introduced by event processing. However, most
		294	callbacks do not expect large delays in processing, so this causes a
		295	higher drift (and a lot more system calls to get the current time).
		296
		297	In another sense, L<EV> is more exact, as your timer will be scheduled at
		298	the same time, regardless of how long event processing actually took.
		299
		300	In either case, if you care (and in most cases, you don't), then you
		301	can get whatever behaviour you want with any event loop, by taking the
		302	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		303	account.
		304
		305	=back
		306
233	=head2 SIGNAL WATCHERS	307	=head2 SIGNAL WATCHERS
234		308
235	You can watch for signals using a signal watcher, C<signal> is the signal	309	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	310	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
237	be invoked whenever a signal occurs.	311	be invoked whenever a signal occurs.
238		312
239	Although the callback might get passed parameters, their value and	313	Although the callback might get passed parameters, their value and
240	presence is undefined and you cannot rely on them. Portable AnyEvent	314	presence is undefined and you cannot rely on them. Portable AnyEvent
241	callbacks cannot use arguments passed to signal watcher callbacks.	315	callbacks cannot use arguments passed to signal watcher callbacks.
242		316
243	Multiple signal occurances can be clumped together into one callback	317	Multiple signal occurrences can be clumped together into one callback
244	invocation, and callback invocation will be synchronous. synchronous means	318	invocation, and callback invocation will be synchronous. Synchronous means
245	that it might take a while until the signal gets handled by the process,	319	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.	320	but it is guaranteed not to interrupt any other callbacks.
247		321
248	The main advantage of using these watchers is that you can share a signal	322	The main advantage of using these watchers is that you can share a signal
249	between multiple watchers.	323	between multiple watchers.
250		324
251	This watcher might use C<%SIG>, so programs overwriting those signals	325	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
278	AnyEvent program, you I<have> to create at least one watcher before you	352	AnyEvent program, you I<have> to create at least one watcher before you
279	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	353	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
280		354
281	Example: fork a process and wait for it	355	Example: fork a process and wait for it
282		356
283	my $done = AnyEvent->condvar;	357	my $done = AnyEvent->condvar;
284		358
285	AnyEvent::detect; # force event module to be initialised
286
287	my $pid = fork or exit 5;	359	my $pid = fork or exit 5;
288		360
289	my $w = AnyEvent->child (	361	my $w = AnyEvent->child (
290	pid => $pid,	362	pid => $pid,
291	cb => sub {	363	cb => sub {
292	my ($pid, $status) = @_;	364	my ($pid, $status) = @_;
293	warn "pid $pid exited with status $status";	365	warn "pid $pid exited with status $status";
294	$done->broadcast;	366	$done->send;
295	},	367	},
296	);	368	);
297		369
298	# do something else, then wait for process exit	370	# do something else, then wait for process exit
299	$done->wait;	371	$done->recv;
300		372
301	=head2 CONDITION VARIABLES	373	=head2 CONDITION VARIABLES
302		374
		375	If you are familiar with some event loops you will know that all of them
		376	require you to run some blocking "loop", "run" or similar function that
		377	will actively watch for new events and call your callbacks.
		378
		379	AnyEvent is different, it expects somebody else to run the event loop and
		380	will only block when necessary (usually when told by the user).
		381
		382	The instrument to do that is called a "condition variable", so called
		383	because they represent a condition that must become true.
		384
303	Condition variables can be created by calling the C<< AnyEvent->condvar >>	385	Condition variables can be created by calling the C<< AnyEvent->condvar
304	method without any arguments.	386	>> method, usually without arguments. The only argument pair allowed is
		387	C<cb>, which specifies a callback to be called when the condition variable
		388	becomes true.
305		389
306	A condition variable waits for a condition - precisely that the C<<	390	After creation, the condition variable is "false" until it becomes "true"
307	->broadcast >> method has been called.	391	by calling the C<send> method (or calling the condition variable as if it
		392	were a callback, read about the caveats in the description for the C<<
		393	->send >> method).
308		394
309	They are very useful to signal that a condition has been fulfilled, for	395	Condition variables are similar to callbacks, except that you can
		396	optionally wait for them. They can also be called merge points - points
		397	in time where multiple outstanding events have been processed. And yet
		398	another way to call them is transactions - each condition variable can be
		399	used to represent a transaction, which finishes at some point and delivers
		400	a result.
		401
		402	Condition variables are very useful to signal that something has finished,
310	example, if you write a module that does asynchronous http requests,	403	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	404	then a condition variable would be the ideal candidate to signal the
312	availability of results.	405	availability of results. The user can either act when the callback is
		406	called or can synchronously C<< ->recv >> for the results.
313		407
314	You can also use condition variables to block your main program until	408	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	409	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<<	410	could C<< ->recv >> in your main program until the user clicks the Quit
317	->broadcast >> the "quit" event.	411	button of your app, which would C<< ->send >> the "quit" event.
318		412
319	Note that condition variables recurse into the event loop - if you have	413	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	414	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	415	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,	416	you should avoid making a blocking wait yourself, at least in callbacks,
323	as this asks for trouble.	417	as this asks for trouble.
324		418
325	This object has two methods:	419	Condition variables are represented by hash refs in perl, and the keys
		420	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		421	easy (it is often useful to build your own transaction class on top of
		422	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		423	it's C<new> method in your own C<new> method.
		424
		425	There are two "sides" to a condition variable - the "producer side" which
		426	eventually calls C<< -> send >>, and the "consumer side", which waits
		427	for the send to occur.
		428
		429	Example: wait for a timer.
		430
		431	# wait till the result is ready
		432	my $result_ready = AnyEvent->condvar;
		433
		434	# do something such as adding a timer
		435	# or socket watcher the calls $result_ready->send
		436	# when the "result" is ready.
		437	# in this case, we simply use a timer:
		438	my $w = AnyEvent->timer (
		439	after => 1,
		440	cb => sub { $result_ready->send },
		441	);
		442
		443	# this "blocks" (while handling events) till the callback
		444	# calls send
		445	$result_ready->recv;
		446
		447	Example: wait for a timer, but take advantage of the fact that
		448	condition variables are also code references.
		449
		450	my $done = AnyEvent->condvar;
		451	my $delay = AnyEvent->timer (after => 5, cb => $done);
		452	$done->recv;
		453
		454	=head3 METHODS FOR PRODUCERS
		455
		456	These methods should only be used by the producing side, i.e. the
		457	code/module that eventually sends the signal. Note that it is also
		458	the producer side which creates the condvar in most cases, but it isn't
		459	uncommon for the consumer to create it as well.
326		460
327	=over 4	461	=over 4
328		462
		463	=item $cv->send (...)
		464
		465	Flag the condition as ready - a running C<< ->recv >> and all further
		466	calls to C<recv> will (eventually) return after this method has been
		467	called. If nobody is waiting the send will be remembered.
		468
		469	If a callback has been set on the condition variable, it is called
		470	immediately from within send.
		471
		472	Any arguments passed to the C<send> call will be returned by all
		473	future C<< ->recv >> calls.
		474
		475	Condition variables are overloaded so one can call them directly
		476	(as a code reference). Calling them directly is the same as calling
		477	C<send>. Note, however, that many C-based event loops do not handle
		478	overloading, so as tempting as it may be, passing a condition variable
		479	instead of a callback does not work. Both the pure perl and EV loops
		480	support overloading, however, as well as all functions that use perl to
		481	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		482	example).
		483
		484	=item $cv->croak ($error)
		485
		486	Similar to send, but causes all call's to C<< ->recv >> to invoke
		487	C<Carp::croak> with the given error message/object/scalar.
		488
		489	This can be used to signal any errors to the condition variable
		490	user/consumer.
		491
		492	=item $cv->begin ([group callback])
		493
329	=item $cv->wait	494	=item $cv->end
330		495
331	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	496	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		497
		498	These two methods can be used to combine many transactions/events into
		499	one. For example, a function that pings many hosts in parallel might want
		500	to use a condition variable for the whole process.
		501
		502	Every call to C<< ->begin >> will increment a counter, and every call to
		503	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		504	>>, the (last) callback passed to C<begin> will be executed. That callback
		505	is I<supposed> to call C<< ->send >>, but that is not required. If no
		506	callback was set, C<send> will be called without any arguments.
		507
		508	Let's clarify this with the ping example:
		509
		510	my $cv = AnyEvent->condvar;
		511
		512	my %result;
		513	$cv->begin (sub { $cv->send (\%result) });
		514
		515	for my $host (@list_of_hosts) {
		516	$cv->begin;
		517	ping_host_then_call_callback $host, sub {
		518	$result{$host} = ...;
		519	$cv->end;
		520	};
		521	}
		522
		523	$cv->end;
		524
		525	This code fragment supposedly pings a number of hosts and calls
		526	C<send> after results for all then have have been gathered - in any
		527	order. To achieve this, the code issues a call to C<begin> when it starts
		528	each ping request and calls C<end> when it has received some result for
		529	it. Since C<begin> and C<end> only maintain a counter, the order in which
		530	results arrive is not relevant.
		531
		532	There is an additional bracketing call to C<begin> and C<end> outside the
		533	loop, which serves two important purposes: first, it sets the callback
		534	to be called once the counter reaches C<0>, and second, it ensures that
		535	C<send> is called even when C<no> hosts are being pinged (the loop
		536	doesn't execute once).
		537
		538	This is the general pattern when you "fan out" into multiple subrequests:
		539	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		540	is called at least once, and then, for each subrequest you start, call
		541	C<begin> and for each subrequest you finish, call C<end>.
		542
		543	=back
		544
		545	=head3 METHODS FOR CONSUMERS
		546
		547	These methods should only be used by the consuming side, i.e. the
		548	code awaits the condition.
		549
		550	=over 4
		551
		552	=item $cv->recv
		553
		554	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
332	called on c<$cv>, while servicing other watchers normally.	555	>> methods have been called on c<$cv>, while servicing other watchers
		556	normally.
333		557
334	You can only wait once on a condition - additional calls will return	558	You can only wait once on a condition - additional calls are valid but
335	immediately.	559	will return immediately.
		560
		561	If an error condition has been set by calling C<< ->croak >>, then this
		562	function will call C<croak>.
		563
		564	In list context, all parameters passed to C<send> will be returned,
		565	in scalar context only the first one will be returned.
336		566
337	Not all event models support a blocking wait - some die in that case	567	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	568	(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	569	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	570	caller decide whether the call will block or not (for example, by coupling
341	condition variables with some kind of request results and supporting	571	condition variables with some kind of request results and supporting
342	callbacks so the caller knows that getting the result will not block,	572	callbacks so the caller knows that getting the result will not block,
343	while still suppporting blocking waits if the caller so desires).	573	while still supporting blocking waits if the caller so desires).
344		574
345	Another reason I<never> to C<< ->wait >> in a module is that you cannot	575	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	576	sensibly have two C<< ->recv >>'s in parallel, as that would require
347	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	577	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
348	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	578	can supply.
349	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
350	from different coroutines, however).
351		579
352	=item $cv->broadcast	580	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		581	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		582	versions and also integrates coroutines into AnyEvent, making blocking
		583	C<< ->recv >> calls perfectly safe as long as they are done from another
		584	coroutine (one that doesn't run the event loop).
353		585
354	Flag the condition as ready - a running C<< ->wait >> and all further	586	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	587	only calling C<< ->recv >> from within that callback (or at a later
356	called. If nobody is waiting the broadcast will be remembered..	588	time). This will work even when the event loop does not support blocking
		589	waits otherwise.
		590
		591	=item $bool = $cv->ready
		592
		593	Returns true when the condition is "true", i.e. whether C<send> or
		594	C<croak> have been called.
		595
		596	=item $cb = $cv->cb ([new callback])
		597
		598	This is a mutator function that returns the callback set and optionally
		599	replaces it before doing so.
		600
		601	The callback will be called when the condition becomes "true", i.e. when
		602	C<send> or C<croak> are called, with the only argument being the condition
		603	variable itself. Calling C<recv> inside the callback or at any later time
		604	is guaranteed not to block.
357		605
358	=back	606	=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	$result_ready->wait;
377		607
378	=head1 GLOBAL VARIABLES AND FUNCTIONS	608	=head1 GLOBAL VARIABLES AND FUNCTIONS
379		609
380	=over 4	610	=over 4
381		611
…		…
387	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	617	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
388	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	618	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
389		619
390	The known classes so far are:	620	The known classes so far are:
391		621
392	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
393	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
394	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	622	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
395	AnyEvent::Impl::Event based on Event, second best choice.	623	AnyEvent::Impl::Event based on Event, second best choice.
		624	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
396	AnyEvent::Impl::Glib based on Glib, third-best choice.	625	AnyEvent::Impl::Glib based on Glib, third-best choice.
397	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
398	AnyEvent::Impl::Tk based on Tk, very bad choice.	626	AnyEvent::Impl::Tk based on Tk, very bad choice.
399	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	627	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
400	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	628	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
401	AnyEvent::Impl::POE based on POE, not generic enough for full support.	629	AnyEvent::Impl::POE based on POE, not generic enough for full support.
402		630
…		…
415	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	643	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
416	if necessary. You should only call this function right before you would	644	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	645	have created an AnyEvent watcher anyway, that is, as late as possible at
418	runtime.	646	runtime.
419		647
		648	=item $guard = AnyEvent::post_detect { BLOCK }
		649
		650	Arranges for the code block to be executed as soon as the event model is
		651	autodetected (or immediately if this has already happened).
		652
		653	If called in scalar or list context, then it creates and returns an object
		654	that automatically removes the callback again when it is destroyed. See
		655	L<Coro::BDB> for a case where this is useful.
		656
		657	=item @AnyEvent::post_detect
		658
		659	If there are any code references in this array (you can C<push> to it
		660	before or after loading AnyEvent), then they will called directly after
		661	the event loop has been chosen.
		662
		663	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		664	if it contains a true value then the event loop has already been detected,
		665	and the array will be ignored.
		666
		667	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		668
420	=back	669	=back
421		670
422	=head1 WHAT TO DO IN A MODULE	671	=head1 WHAT TO DO IN A MODULE
423		672
424	As a module author, you should C<use AnyEvent> and call AnyEvent methods	673	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	676	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	677	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	678	by calling AnyEvent in your module body you force the user of your module
430	to load the event module first.	679	to load the event module first.
431		680
432	Never call C<< ->wait >> on a condition variable unless you I<know> that	681	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	682	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	683	because it will stall the whole program, and the whole point of using
435	events is to stay interactive.	684	events is to stay interactive.
436		685
437	It is fine, however, to call C<< ->wait >> when the user of your module	686	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	687	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 >>	688	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).	689	freely, as the user of your module knows what she is doing. always).
441		690
442	=head1 WHAT TO DO IN THE MAIN PROGRAM	691	=head1 WHAT TO DO IN THE MAIN PROGRAM
443		692
444	There will always be a single main program - the only place that should	693	There will always be a single main program - the only place that should
…		…
446		695
447	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	696	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	697	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.	698	decide which implementation to chose if some module relies on it.
450		699
451	If the main program relies on a specific event model. For example, in	700	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	701	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	702	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	703	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	704	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	705	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.	706	might chose the wrong one unless you load the correct one yourself.
458		707
459	You can chose to use a rather inefficient pure-perl implementation by	708	You can chose to use a pure-perl implementation by loading the
460	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	709	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
461	behaviour everywhere, but letting AnyEvent chose is generally better.	710	everywhere, but letting AnyEvent chose the model is generally better.
		711
		712	=head2 MAINLOOP EMULATION
		713
		714	Sometimes (often for short test scripts, or even standalone programs who
		715	only want to use AnyEvent), you do not want to run a specific event loop.
		716
		717	In that case, you can use a condition variable like this:
		718
		719	AnyEvent->condvar->recv;
		720
		721	This has the effect of entering the event loop and looping forever.
		722
		723	Note that usually your program has some exit condition, in which case
		724	it is better to use the "traditional" approach of storing a condition
		725	variable somewhere, waiting for it, and sending it when the program should
		726	exit cleanly.
		727
		728
		729	=head1 OTHER MODULES
		730
		731	The following is a non-exhaustive list of additional modules that use
		732	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		733	in the same program. Some of the modules come with AnyEvent, some are
		734	available via CPAN.
		735
		736	=over 4
		737
		738	=item L<AnyEvent::Util>
		739
		740	Contains various utility functions that replace often-used but blocking
		741	functions such as C<inet_aton> by event-/callback-based versions.
		742
		743	=item L<AnyEvent::Handle>
		744
		745	Provide read and write buffers and manages watchers for reads and writes.
		746
		747	=item L<AnyEvent::Socket>
		748
		749	Provides various utility functions for (internet protocol) sockets,
		750	addresses and name resolution. Also functions to create non-blocking tcp
		751	connections or tcp servers, with IPv6 and SRV record support and more.
		752
		753	=item L<AnyEvent::DNS>
		754
		755	Provides rich asynchronous DNS resolver capabilities.
		756
		757	=item L<AnyEvent::HTTPD>
		758
		759	Provides a simple web application server framework.
		760
		761	=item L<AnyEvent::FastPing>
		762
		763	The fastest ping in the west.
		764
		765	=item L<Net::IRC3>
		766
		767	AnyEvent based IRC client module family.
		768
		769	=item L<Net::XMPP2>
		770
		771	AnyEvent based XMPP (Jabber protocol) module family.
		772
		773	=item L<Net::FCP>
		774
		775	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		776	of AnyEvent.
		777
		778	=item L<Event::ExecFlow>
		779
		780	High level API for event-based execution flow control.
		781
		782	=item L<Coro>
		783
		784	Has special support for AnyEvent via L<Coro::AnyEvent>.
		785
		786	=item L<AnyEvent::AIO>, L<IO::AIO>
		787
		788	Truly asynchronous I/O, should be in the toolbox of every event
		789	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
		790	together.
		791
		792	=item L<AnyEvent::BDB>, L<BDB>
		793
		794	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
		795	IO::AIO and AnyEvent together.
		796
		797	=item L<IO::Lambda>
		798
		799	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		800
		801	=back
462		802
463	=cut	803	=cut
464		804
465	package AnyEvent;	805	package AnyEvent;
466		806
467	no warnings;	807	no warnings;
468	use strict;	808	use strict;
469		809
470	use Carp;	810	use Carp;
471		811
472	our $VERSION = '3.3';	812	our $VERSION = 4.12;
473	our $MODEL;	813	our $MODEL;
474		814
475	our $AUTOLOAD;	815	our $AUTOLOAD;
476	our @ISA;	816	our @ISA;
477		817
		818	our @REGISTRY;
		819
		820	our $WIN32;
		821
		822	BEGIN {
		823	my $win32 = ! ! ($^O =~ /mswin32/i);
		824	eval "sub WIN32(){ $win32 }";
		825	}
		826
478	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	827	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
479		828
480	our @REGISTRY;	829	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
		830
		831	{
		832	my $idx;
		833	$PROTOCOL{$_} = ++$idx
		834	for reverse split /\s,\s/,
		835	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		836	}
481		837
482	my @models = (	838	my @models = (
483	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
484	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
485	[EV:: => AnyEvent::Impl::EV::],	839	[EV:: => AnyEvent::Impl::EV::],
486	[Event:: => AnyEvent::Impl::Event::],	840	[Event:: => AnyEvent::Impl::Event::],
487	[Glib:: => AnyEvent::Impl::Glib::],
488	[Tk:: => AnyEvent::Impl::Tk::],
489	[Wx:: => AnyEvent::Impl::POE::],
490	[Prima:: => AnyEvent::Impl::POE::],
491	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	841	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
492	# everything below here will not be autoprobed as the pureperl backend should work everywhere	842	# everything below here will not be autoprobed
		843	# as the pureperl backend should work everywhere
		844	# and is usually faster
		845	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		846	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
493	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	847	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
494	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	848	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
495	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	849	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		850	[Wx:: => AnyEvent::Impl::POE::],
		851	[Prima:: => AnyEvent::Impl::POE::],
496	);	852	);
497		853
498	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	854	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		855
		856	our @post_detect;
		857
		858	sub post_detect(&) {
		859	my ($cb) = @_;
		860
		861	if ($MODEL) {
		862	$cb->();
		863
		864	1
		865	} else {
		866	push @post_detect, $cb;
		867
		868	defined wantarray
		869	? bless \$cb, "AnyEvent::Util::PostDetect"
		870	: ()
		871	}
		872	}
		873
		874	sub AnyEvent::Util::PostDetect::DESTROY {
		875	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		876	}
499		877
500	sub detect() {	878	sub detect() {
501	unless ($MODEL) {	879	unless ($MODEL) {
502	no strict 'refs';	880	no strict 'refs';
		881	local $SIG{__DIE__};
503		882
504	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	883	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
505	my $model = "AnyEvent::Impl::$1";	884	my $model = "AnyEvent::Impl::$1";
506	if (eval "require $model") {	885	if (eval "require $model") {
507	$MODEL = $model;	886	$MODEL = $model;
…		…
537	last;	916	last;
538	}	917	}
539	}	918	}
540		919
541	$MODEL	920	$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.";	921	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
543	}	922	}
544	}	923	}
545		924
546	unshift @ISA, $MODEL;	925	unshift @ISA, $MODEL;
547	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	926	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		927
		928	(shift @post_detect)->() while @post_detect;
548	}	929	}
549		930
550	$MODEL	931	$MODEL
551	}	932	}
552		933
…		…
562	$class->$func (@_);	943	$class->$func (@_);
563	}	944	}
564		945
565	package AnyEvent::Base;	946	package AnyEvent::Base;
566		947
		948	# default implementation for now and time
		949
		950	use Time::HiRes ();
		951
		952	sub time { Time::HiRes::time }
		953	sub now { Time::HiRes::time }
		954
567	# default implementation for ->condvar, ->wait, ->broadcast	955	# default implementation for ->condvar
568		956
569	sub condvar {	957	sub condvar {
570	bless \my $flag, "AnyEvent::Base::CondVar"	958	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	}	959	}
580		960
581	# default implementation for ->signal	961	# default implementation for ->signal
582		962
583	our %SIG_CB;	963	our %SIG_CB;
…		…
636	or Carp::croak "required option 'pid' is missing";	1016	or Carp::croak "required option 'pid' is missing";
637		1017
638	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1018	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
639		1019
640	unless ($WNOHANG) {	1020	unless ($WNOHANG) {
641	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1021	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
642	}	1022	}
643		1023
644	unless ($CHLD_W) {	1024	unless ($CHLD_W) {
645	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1025	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
646	# child could be a zombie already, so make at least one round	1026	# child could be a zombie already, so make at least one round
…		…
656	delete $PID_CB{$pid}{$cb};	1036	delete $PID_CB{$pid}{$cb};
657	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1037	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
658		1038
659	undef $CHLD_W unless keys %PID_CB;	1039	undef $CHLD_W unless keys %PID_CB;
660	}	1040	}
		1041
		1042	package AnyEvent::CondVar;
		1043
		1044	our @ISA = AnyEvent::CondVar::Base::;
		1045
		1046	package AnyEvent::CondVar::Base;
		1047
		1048	use overload
		1049	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1050	fallback => 1;
		1051
		1052	sub _send {
		1053	# nop
		1054	}
		1055
		1056	sub send {
		1057	my $cv = shift;
		1058	$cv->{_ae_sent} = [@_];
		1059	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1060	$cv->_send;
		1061	}
		1062
		1063	sub croak {
		1064	$_[0]{_ae_croak} = $_[1];
		1065	$_[0]->send;
		1066	}
		1067
		1068	sub ready {
		1069	$_[0]{_ae_sent}
		1070	}
		1071
		1072	sub _wait {
		1073	AnyEvent->one_event while !$_[0]{_ae_sent};
		1074	}
		1075
		1076	sub recv {
		1077	$_[0]->_wait;
		1078
		1079	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1080	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1081	}
		1082
		1083	sub cb {
		1084	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1085	$_[0]{_ae_cb}
		1086	}
		1087
		1088	sub begin {
		1089	++$_[0]{_ae_counter};
		1090	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1091	}
		1092
		1093	sub end {
		1094	return if --$_[0]{_ae_counter};
		1095	&{ $_[0]{_ae_end_cb} \|\| sub { $_[0]->send } };
		1096	}
		1097
		1098	# undocumented/compatibility with pre-3.4
		1099	*broadcast = \&send;
		1100	*wait = \&_wait;
661		1101
662	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1102	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
663		1103
664	This is an advanced topic that you do not normally need to use AnyEvent in	1104	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	1105	a module. This section is only of use to event loop authors who want to
…		…
722	model it chooses.	1162	model it chooses.
723		1163
724	=item C<PERL_ANYEVENT_MODEL>	1164	=item C<PERL_ANYEVENT_MODEL>
725		1165
726	This can be used to specify the event model to be used by AnyEvent, before	1166	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	1167	auto detection and -probing kicks in. It must be a string consisting
728	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1168	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,	1169	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	1170	used as event model. If it fails to load AnyEvent will proceed with
731	autodetection and -probing.	1171	auto detection and -probing.
732		1172
733	This functionality might change in future versions.	1173	This functionality might change in future versions.
734		1174
735	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1175	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
736	could start your program like this:	1176	could start your program like this:
737		1177
738	PERL_ANYEVENT_MODEL=Perl perl ...	1178	PERL_ANYEVENT_MODEL=Perl perl ...
		1179
		1180	=item C<PERL_ANYEVENT_PROTOCOLS>
		1181
		1182	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1183	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1184	of auto probing).
		1185
		1186	Must be set to a comma-separated list of protocols or address families,
		1187	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1188	used, and preference will be given to protocols mentioned earlier in the
		1189	list.
		1190
		1191	This variable can effectively be used for denial-of-service attacks
		1192	against local programs (e.g. when setuid), although the impact is likely
		1193	small, as the program has to handle connection errors already-
		1194
		1195	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1196	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1197	- only support IPv4, never try to resolve or contact IPv6
		1198	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1199	IPv6, but prefer IPv6 over IPv4.
		1200
		1201	=item C<PERL_ANYEVENT_EDNS0>
		1202
		1203	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1204	for DNS. This extension is generally useful to reduce DNS traffic, but
		1205	some (broken) firewalls drop such DNS packets, which is why it is off by
		1206	default.
		1207
		1208	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1209	EDNS0 in its DNS requests.
		1210
		1211	=item C<PERL_ANYEVENT_MAX_FORKS>
		1212
		1213	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1214	will create in parallel.
739		1215
740	=back	1216	=back
741		1217
742	=head1 EXAMPLE PROGRAM	1218	=head1 EXAMPLE PROGRAM
743		1219
…		…
754	poll => 'r',	1230	poll => 'r',
755	cb => sub {	1231	cb => sub {
756	warn "io event <$_[0]>\n"; # will always output <r>	1232	warn "io event <$_[0]>\n"; # will always output <r>
757	chomp (my $input = <STDIN>); # read a line	1233	chomp (my $input = <STDIN>); # read a line
758	warn "read: $input\n"; # output what has been read	1234	warn "read: $input\n"; # output what has been read
759	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1235	$cv->send if $input =~ /^q/i; # quit program if /^q/i
760	},	1236	},
761	);	1237	);
762		1238
763	my $time_watcher; # can only be used once	1239	my $time_watcher; # can only be used once
764		1240
…		…
769	});	1245	});
770	}	1246	}
771		1247
772	new_timer; # create first timer	1248	new_timer; # create first timer
773		1249
774	$cv->wait; # wait until user enters /^q/i	1250	$cv->recv; # wait until user enters /^q/i
775		1251
776	=head1 REAL-WORLD EXAMPLE	1252	=head1 REAL-WORLD EXAMPLE
777		1253
778	Consider the L<Net::FCP> module. It features (among others) the following	1254	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:	1255	API calls, which are to freenet what HTTP GET requests are to http:
…		…
829	syswrite $txn->{fh}, $txn->{request}	1305	syswrite $txn->{fh}, $txn->{request}
830	or die "connection or write error";	1306	or die "connection or write error";
831	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1307	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
832		1308
833	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1309	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:	1310	result and signals any possible waiters that the request has finished:
835		1311
836	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1312	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
837		1313
838	if (end-of-file or data complete) {	1314	if (end-of-file or data complete) {
839	$txn->{result} = $txn->{buf};	1315	$txn->{result} = $txn->{buf};
840	$txn->{finished}->broadcast;	1316	$txn->{finished}->send;
841	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1317	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
842	}	1318	}
843		1319
844	The C<result> method, finally, just waits for the finished signal (if the	1320	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	1321	request was already finished, it doesn't wait, of course, and returns the
846	data:	1322	data:
847		1323
848	$txn->{finished}->wait;	1324	$txn->{finished}->recv;
849	return $txn->{result};	1325	return $txn->{result};
850		1326
851	The actual code goes further and collects all errors (C<die>s, exceptions)	1327	The actual code goes further and collects all errors (C<die>s, exceptions)
852	that occured during request processing. The C<result> method detects	1328	that occurred during request processing. The C<result> method detects
853	whether an exception as thrown (it is stored inside the $txn object)	1329	whether an exception as thrown (it is stored inside the $txn object)
854	and just throws the exception, which means connection errors and other	1330	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	1331	problems get reported tot he code that tries to use the result, not in a
856	random callback.	1332	random callback.
857		1333
…		…
888		1364
889	my $quit = AnyEvent->condvar;	1365	my $quit = AnyEvent->condvar;
890		1366
891	$fcp->txn_client_get ($url)->cb (sub {	1367	$fcp->txn_client_get ($url)->cb (sub {
892	...	1368	...
893	$quit->broadcast;	1369	$quit->send;
894	});	1370	});
895		1371
896	$quit->wait;	1372	$quit->recv;
897		1373
898		1374
899	=head1 BENCHMARK	1375	=head1 BENCHMARKS
900		1376
901	To give you an idea of the performance and overheads that AnyEvent adds	1377	To give you an idea of the performance and overheads that AnyEvent adds
902	over the event loops themselves (and to give you an impression of the	1378	over the event loops themselves and to give you an impression of the speed
903	speed of various event loops), here is a benchmark of various supported	1379	of various event loops I prepared some benchmarks.
904	event models natively and with anyevent. The benchmark creates a lot of	1380
905	timers (with a zero timeout) and I/O watchers (watching STDOUT, a pty, to	1381	=head2 BENCHMARKING ANYEVENT OVERHEAD
		1382
		1383	Here is a benchmark of various supported event models used natively and
		1384	through AnyEvent. The benchmark creates a lot of timers (with a zero
		1385	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
906	become writable, which it is), lets them fire exactly once and destroys	1386	which it is), lets them fire exactly once and destroys them again.
907	them again.
908		1387
909	Rewriting the benchmark to use many different sockets instead of using	1388	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
910	the same filehandle for all I/O watchers results in a much longer runtime	1389	distribution.
911	(socket creation is expensive), but qualitatively the same figures, so it
912	was not used.
913		1390
914	=head2 Explanation of the columns	1391	=head3 Explanation of the columns
915		1392
916	I<watcher> is the number of event watchers created/destroyed. Since	1393	I<watcher> is the number of event watchers created/destroyed. Since
917	different event models feature vastly different performances, each event	1394	different event models feature vastly different performances, each event
918	loop was given a number of watchers so that overall runtime is acceptable	1395	loop was given a number of watchers so that overall runtime is acceptable
919	and similar between tested event loop (and keep them from crashing): Glib	1396	and similar between tested event loop (and keep them from crashing): Glib
…		…
929	all watchers, to avoid adding memory overhead. That means closure creation	1406	all watchers, to avoid adding memory overhead. That means closure creation
930	and memory usage is not included in the figures.	1407	and memory usage is not included in the figures.
931		1408
932	I<invoke> is the time, in microseconds, used to invoke a simple	1409	I<invoke> is the time, in microseconds, used to invoke a simple
933	callback. The callback simply counts down a Perl variable and after it was	1410	callback. The callback simply counts down a Perl variable and after it was
934	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1411	invoked "watcher" times, it would C<< ->send >> a condvar once to
935	signal the end of this phase.	1412	signal the end of this phase.
936		1413
937	I<destroy> is the time, in microseconds, that it takes to destroy a single	1414	I<destroy> is the time, in microseconds, that it takes to destroy a single
938	watcher.	1415	watcher.
939		1416
940	=head2 Results	1417	=head3 Results
941		1418
942	name watchers bytes create invoke destroy comment	1419	name watchers bytes create invoke destroy comment
943	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1420	EV/EV 400000 244 0.56 0.46 0.31 EV native interface
944	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1421	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers
945	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1422	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal
946	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1423	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation
947	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1424	Event/Event 16000 516 31.88 31.30 0.85 Event native interface
948	Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers	1425	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers
949	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1426	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour
950	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1427	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers
951	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1428	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event
952	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1429	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select
953		1430
954	=head2 Discussion	1431	=head3 Discussion
955		1432
956	The benchmark does I<not> measure scalability of the event loop very	1433	The benchmark does I<not> measure scalability of the event loop very
957	well. For example, a select-based event loop (such as the pure perl one)	1434	well. For example, a select-based event loop (such as the pure perl one)
958	can never compete with an event loop that uses epoll when the number of	1435	can never compete with an event loop that uses epoll when the number of
959	file descriptors grows high. In this benchmark, all events become ready at	1436	file descriptors grows high. In this benchmark, all events become ready at
960	the same time, so select/poll-based implementations get an unnatural speed	1437	the same time, so select/poll-based implementations get an unnatural speed
961	boost.	1438	boost.
		1439
		1440	Also, note that the number of watchers usually has a nonlinear effect on
		1441	overall speed, that is, creating twice as many watchers doesn't take twice
		1442	the time - usually it takes longer. This puts event loops tested with a
		1443	higher number of watchers at a disadvantage.
		1444
		1445	To put the range of results into perspective, consider that on the
		1446	benchmark machine, handling an event takes roughly 1600 CPU cycles with
		1447	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
		1448	cycles with POE.
962		1449
963	C<EV> is the sole leader regarding speed and memory use, which are both	1450	C<EV> is the sole leader regarding speed and memory use, which are both
964	maximal/minimal, respectively. Even when going through AnyEvent, it uses	1451	maximal/minimal, respectively. Even when going through AnyEvent, it uses
965	far less memory than any other event loop and is still faster than Event	1452	far less memory than any other event loop and is still faster than Event
966	natively.	1453	natively.
…		…
989	file descriptor is dup()ed for each watcher. This shows that the dup()	1476	file descriptor is dup()ed for each watcher. This shows that the dup()
990	employed by some adaptors is not a big performance issue (it does incur a	1477	employed by some adaptors is not a big performance issue (it does incur a
991	hidden memory cost inside the kernel which is not reflected in the figures	1478	hidden memory cost inside the kernel which is not reflected in the figures
992	above).	1479	above).
993		1480
994	C<POE>, regardless of underlying event loop (whether using its pure	1481	C<POE>, regardless of underlying event loop (whether using its pure perl
995	perl select-based backend or the Event module, the POE-EV backend	1482	select-based backend or the Event module, the POE-EV backend couldn't
996	couldn't be tested because it wasn't working) shows abysmal performance	1483	be tested because it wasn't working) shows abysmal performance and
997	and memory usage: Watchers use almost 30 times as much memory as	1484	memory usage with AnyEvent: Watchers use almost 30 times as much memory
998	EV watchers, and 10 times as much memory as Event (the high memory	1485	as EV watchers, and 10 times as much memory as Event (the high memory
999	requirements are caused by requiring a session for each watcher). Watcher	1486	requirements are caused by requiring a session for each watcher). Watcher
1000	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1487	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1488	implementation.
		1489
1001	implementation. The design of the POE adaptor class in AnyEvent can not	1490	The design of the POE adaptor class in AnyEvent can not really account
1002	really account for this, as session creation overhead is small compared	1491	for the performance issues, though, as session creation overhead is
1003	to execution of the state machine, which is coded pretty optimally within	1492	small compared to execution of the state machine, which is coded pretty
1004	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1493	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1494	using multiple sessions is not a good approach, especially regarding
		1495	memory usage, even the author of POE could not come up with a faster
		1496	design).
1005		1497
1006	=head2 Summary	1498	=head3 Summary
1007		1499
1008	=over 4	1500	=over 4
1009		1501
1010	=item * Using EV through AnyEvent is faster than any other event loop	1502	=item * Using EV through AnyEvent is faster than any other event loop
1011	(even when used without AnyEvent), but most event loops have acceptable	1503	(even when used without AnyEvent), but most event loops have acceptable
…		…
1018	=item * You should avoid POE like the plague if you want performance or	1510	=item * You should avoid POE like the plague if you want performance or
1019	reasonable memory usage.	1511	reasonable memory usage.
1020		1512
1021	=back	1513	=back
1022		1514
		1515	=head2 BENCHMARKING THE LARGE SERVER CASE
		1516
		1517	This benchmark actually benchmarks the event loop itself. It works by
		1518	creating a number of "servers": each server consists of a socket pair, a
		1519	timeout watcher that gets reset on activity (but never fires), and an I/O
		1520	watcher waiting for input on one side of the socket. Each time the socket
		1521	watcher reads a byte it will write that byte to a random other "server".
		1522
		1523	The effect is that there will be a lot of I/O watchers, only part of which
		1524	are active at any one point (so there is a constant number of active
		1525	fds for each loop iteration, but which fds these are is random). The
		1526	timeout is reset each time something is read because that reflects how
		1527	most timeouts work (and puts extra pressure on the event loops).
		1528
		1529	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
		1530	(1%) are active. This mirrors the activity of large servers with many
		1531	connections, most of which are idle at any one point in time.
		1532
		1533	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
		1534	distribution.
		1535
		1536	=head3 Explanation of the columns
		1537
		1538	I<sockets> is the number of sockets, and twice the number of "servers" (as
		1539	each server has a read and write socket end).
		1540
		1541	I<create> is the time it takes to create a socket pair (which is
		1542	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
		1543
		1544	I<request>, the most important value, is the time it takes to handle a
		1545	single "request", that is, reading the token from the pipe and forwarding
		1546	it to another server. This includes deleting the old timeout and creating
		1547	a new one that moves the timeout into the future.
		1548
		1549	=head3 Results
		1550
		1551	name sockets create request
		1552	EV 20000 69.01 11.16
		1553	Perl 20000 73.32 35.87
		1554	Event 20000 212.62 257.32
		1555	Glib 20000 651.16 1896.30
		1556	POE 20000 349.67 12317.24 uses POE::Loop::Event
		1557
		1558	=head3 Discussion
		1559
		1560	This benchmark I<does> measure scalability and overall performance of the
		1561	particular event loop.
		1562
		1563	EV is again fastest. Since it is using epoll on my system, the setup time
		1564	is relatively high, though.
		1565
		1566	Perl surprisingly comes second. It is much faster than the C-based event
		1567	loops Event and Glib.
		1568
		1569	Event suffers from high setup time as well (look at its code and you will
		1570	understand why). Callback invocation also has a high overhead compared to
		1571	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
		1572	uses select or poll in basically all documented configurations.
		1573
		1574	Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It
		1575	clearly fails to perform with many filehandles or in busy servers.
		1576
		1577	POE is still completely out of the picture, taking over 1000 times as long
		1578	as EV, and over 100 times as long as the Perl implementation, even though
		1579	it uses a C-based event loop in this case.
		1580
		1581	=head3 Summary
		1582
		1583	=over 4
		1584
		1585	=item * The pure perl implementation performs extremely well.
		1586
		1587	=item * Avoid Glib or POE in large projects where performance matters.
		1588
		1589	=back
		1590
		1591	=head2 BENCHMARKING SMALL SERVERS
		1592
		1593	While event loops should scale (and select-based ones do not...) even to
		1594	large servers, most programs we (or I :) actually write have only a few
		1595	I/O watchers.
		1596
		1597	In this benchmark, I use the same benchmark program as in the large server
		1598	case, but it uses only eight "servers", of which three are active at any
		1599	one time. This should reflect performance for a small server relatively
		1600	well.
		1601
		1602	The columns are identical to the previous table.
		1603
		1604	=head3 Results
		1605
		1606	name sockets create request
		1607	EV 16 20.00 6.54
		1608	Perl 16 25.75 12.62
		1609	Event 16 81.27 35.86
		1610	Glib 16 32.63 15.48
		1611	POE 16 261.87 276.28 uses POE::Loop::Event
		1612
		1613	=head3 Discussion
		1614
		1615	The benchmark tries to test the performance of a typical small
		1616	server. While knowing how various event loops perform is interesting, keep
		1617	in mind that their overhead in this case is usually not as important, due
		1618	to the small absolute number of watchers (that is, you need efficiency and
		1619	speed most when you have lots of watchers, not when you only have a few of
		1620	them).
		1621
		1622	EV is again fastest.
		1623
		1624	Perl again comes second. It is noticeably faster than the C-based event
		1625	loops Event and Glib, although the difference is too small to really
		1626	matter.
		1627
		1628	POE also performs much better in this case, but is is still far behind the
		1629	others.
		1630
		1631	=head3 Summary
		1632
		1633	=over 4
		1634
		1635	=item * C-based event loops perform very well with small number of
		1636	watchers, as the management overhead dominates.
		1637
		1638	=back
		1639
1023		1640
1024	=head1 FORK	1641	=head1 FORK
1025		1642
1026	Most event libraries are not fork-safe. The ones who are usually are	1643	Most event libraries are not fork-safe. The ones who are usually are
1027	because they are so inefficient. Only L<EV> is fully fork-aware.	1644	because they rely on inefficient but fork-safe C<select> or C<poll>
		1645	calls. Only L<EV> is fully fork-aware.
1028		1646
1029	If you have to fork, you must either do so I<before> creating your first	1647	If you have to fork, you must either do so I<before> creating your first
1030	watcher OR you must not use AnyEvent at all in the child.	1648	watcher OR you must not use AnyEvent at all in the child.
1031		1649
1032		1650
…		…
1040	specified in the variable.	1658	specified in the variable.
1041		1659
1042	You can make AnyEvent completely ignore this variable by deleting it	1660	You can make AnyEvent completely ignore this variable by deleting it
1043	before the first watcher gets created, e.g. with a C<BEGIN> block:	1661	before the first watcher gets created, e.g. with a C<BEGIN> block:
1044		1662
1045	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1663	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1046		1664
1047	use AnyEvent;	1665	use AnyEvent;
		1666
		1667	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1668	be used to probe what backend is used and gain other information (which is
		1669	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
1048		1670
1049		1671
1050	=head1 SEE ALSO	1672	=head1 SEE ALSO
1051		1673
1052	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1674	Utility functions: L<AnyEvent::Util>.
1053	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1675
		1676	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1054	L<Event::Lib>, L<Qt>, L<POE>.	1677	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1055		1678
1056	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1679	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1057	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1680	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1058	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1681	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1059	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1682	L<AnyEvent::Impl::POE>.
1060		1683
		1684	Non-blocking file handles, sockets, TCP clients and
		1685	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1686
		1687	Asynchronous DNS: L<AnyEvent::DNS>.
		1688
		1689	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1690
1061	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1691	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1062		1692
1063		1693
1064	=head1 AUTHOR	1694	=head1 AUTHOR
1065		1695
1066	Marc Lehmann <schmorp@schmorp.de>	1696	Marc Lehmann <schmorp@schmorp.de>
1067	http://home.schmorp.de/	1697	http://home.schmorp.de/
1068		1698
1069	=cut	1699	=cut
1070		1700
1071	1	1701	1
1072		1702

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.90 by root, Fri Apr 25 14:24:29 2008 UTC vs. Revision 1.152 by root, Tue Jun 3 09:02:46 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.90 by root, Fri Apr 25 14:24:29 2008 UTC vs.
Revision 1.152 by root, Tue Jun 3 09:02:46 2008 UTC