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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.98 by root, Sun Apr 27 16:31:48 2008 UTC vs.
Revision 1.148 by root, Sat May 31 00:40:16 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	#TODO#
72
73	Net::IRC3
74	AnyEvent::HTTPD
75	AnyEvent::DNS
76	IO::AnyEvent
77	Net::FPing
78	Net::XMPP2
79	Coro
80
81	AnyEvent::IRC
82	AnyEvent::HTTPD
83	AnyEvent::DNS
84	AnyEvent::Handle
85	AnyEvent::Socket
86	AnyEvent::FPing
87	AnyEvent::XMPP
88	AnyEvent::SNMP
89	Coro
90		82
91	=head1 DESCRIPTION	83	=head1 DESCRIPTION
92		84
93	L<AnyEvent> provides an identical interface to multiple event loops. This	85	L<AnyEvent> provides an identical interface to multiple event loops. This
94	allows module authors to utilise an event loop without forcing module	86	allows module authors to utilise an event loop without forcing module
…		…
98	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>
99	module.	91	module.
100		92
101	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
102	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
103	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	95	following modules is already loaded: L<EV>,
104	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>,
105	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
106	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
107	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
108	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
…		…
122	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
123	use AnyEvent so their modules work together with others seamlessly...	115	use AnyEvent so their modules work together with others seamlessly...
124		116
125	The pure-perl implementation of AnyEvent is called	117	The pure-perl implementation of AnyEvent is called
126	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
127	explicitly.	119	explicitly and enjoy the high availability of that event loop :)
128		120
129	=head1 WATCHERS	121	=head1 WATCHERS
130		122
131	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
132	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
133	the callback to call, the filehandle to watch, etc.	125	the callback to call, the file handle to watch, etc.
134		126
135	These watchers are normal Perl objects with normal Perl lifetime. After	127	These watchers are normal Perl objects with normal Perl lifetime. After
136	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
137	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
138	is in control).	130	is in control).
…		…
247	timers.	239	timers.
248		240
249	AnyEvent always prefers relative timers, if available, matching the	241	AnyEvent always prefers relative timers, if available, matching the
250	AnyEvent API.	242	AnyEvent API.
251		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
252	=head2 SIGNAL WATCHERS	307	=head2 SIGNAL WATCHERS
253		308
254	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
255	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
256	be invoked whenever a signal occurs.	311	be invoked whenever a signal occurs.
257		312
258	Although the callback might get passed parameters, their value and	313	Although the callback might get passed parameters, their value and
259	presence is undefined and you cannot rely on them. Portable AnyEvent	314	presence is undefined and you cannot rely on them. Portable AnyEvent
260	callbacks cannot use arguments passed to signal watcher callbacks.	315	callbacks cannot use arguments passed to signal watcher callbacks.
261		316
262	Multiple signal occurances can be clumped together into one callback	317	Multiple signal occurrences can be clumped together into one callback
263	invocation, and callback invocation will be synchronous. synchronous means	318	invocation, and callback invocation will be synchronous. Synchronous means
264	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,
265	but it is guarenteed not to interrupt any other callbacks.	320	but it is guaranteed not to interrupt any other callbacks.
266		321
267	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
268	between multiple watchers.	323	between multiple watchers.
269		324
270	This watcher might use C<%SIG>, so programs overwriting those signals	325	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
299		354
300	Example: fork a process and wait for it	355	Example: fork a process and wait for it
301		356
302	my $done = AnyEvent->condvar;	357	my $done = AnyEvent->condvar;
303		358
304	AnyEvent::detect; # force event module to be initialised
305
306	my $pid = fork or exit 5;	359	my $pid = fork or exit 5;
307		360
308	my $w = AnyEvent->child (	361	my $w = AnyEvent->child (
309	pid => $pid,	362	pid => $pid,
310	cb => sub {	363	cb => sub {
311	my ($pid, $status) = @_;	364	my ($pid, $status) = @_;
312	warn "pid $pid exited with status $status";	365	warn "pid $pid exited with status $status";
313	$done->broadcast;	366	$done->send;
314	},	367	},
315	);	368	);
316		369
317	# do something else, then wait for process exit	370	# do something else, then wait for process exit
318	$done->wait;	371	$done->recv;
319		372
320	=head2 CONDITION VARIABLES	373	=head2 CONDITION VARIABLES
321		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
322	Condition variables can be created by calling the C<< AnyEvent->condvar >>	385	Condition variables can be created by calling the C<< AnyEvent->condvar
323	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.
324		389
325	A condition variable waits for a condition - precisely that the C<<	390	After creation, the condition variable is "false" until it becomes "true"
326	->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).
327		394
328	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,
329	example, if you write a module that does asynchronous http requests,	403	for example, if you write a module that does asynchronous http requests,
330	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
331	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.
332		407
333	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,
334	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
335	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
336	->broadcast >> the "quit" event.	411	button of your app, which would C<< ->send >> the "quit" event.
337		412
338	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
339	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
340	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
341	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,
342	as this asks for trouble.	417	as this asks for trouble.
343		418
344	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.
345		460
346	=over 4	461	=over 4
347		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
348	=item $cv->wait	494	=item $cv->end
349		495
350	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 $cv->recv
		553
		554	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
351	called on c<$cv>, while servicing other watchers normally.	555	>> methods have been called on c<$cv>, while servicing other watchers
		556	normally.
352		557
353	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
354	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.
355		566
356	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
357	(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
358	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
359	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
360	condition variables with some kind of request results and supporting	571	condition variables with some kind of request results and supporting
361	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,
362	while still suppporting blocking waits if the caller so desires).	573	while still supporting blocking waits if the caller so desires).
363		574
364	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
365	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
366	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	577	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
367	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	578	can supply.
368	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
369	from different coroutines, however).
370		579
371	=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).
372		585
373	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
374	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
375	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. Calling C<recv> inside the callback
		603	or at any later time is guaranteed not to block.
376		604
377	=back	605	=back
378
379	Example:
380
381	# wait till the result is ready
382	my $result_ready = AnyEvent->condvar;
383
384	# do something such as adding a timer
385	# or socket watcher the calls $result_ready->broadcast
386	# when the "result" is ready.
387	# in this case, we simply use a timer:
388	my $w = AnyEvent->timer (
389	after => 1,
390	cb => sub { $result_ready->broadcast },
391	);
392
393	# this "blocks" (while handling events) till the watcher
394	# calls broadcast
395	$result_ready->wait;
396		606
397	=head1 GLOBAL VARIABLES AND FUNCTIONS	607	=head1 GLOBAL VARIABLES AND FUNCTIONS
398		608
399	=over 4	609	=over 4
400		610
…		…
406	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	616	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
407	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	617	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
408		618
409	The known classes so far are:	619	The known classes so far are:
410		620
411	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
412	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
413	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	621	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
414	AnyEvent::Impl::Event based on Event, second best choice.	622	AnyEvent::Impl::Event based on Event, second best choice.
		623	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
415	AnyEvent::Impl::Glib based on Glib, third-best choice.	624	AnyEvent::Impl::Glib based on Glib, third-best choice.
416	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
417	AnyEvent::Impl::Tk based on Tk, very bad choice.	625	AnyEvent::Impl::Tk based on Tk, very bad choice.
418	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	626	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
419	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	627	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
420	AnyEvent::Impl::POE based on POE, not generic enough for full support.	628	AnyEvent::Impl::POE based on POE, not generic enough for full support.
421		629
…		…
434	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	642	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
435	if necessary. You should only call this function right before you would	643	if necessary. You should only call this function right before you would
436	have created an AnyEvent watcher anyway, that is, as late as possible at	644	have created an AnyEvent watcher anyway, that is, as late as possible at
437	runtime.	645	runtime.
438		646
		647	=item $guard = AnyEvent::post_detect { BLOCK }
		648
		649	Arranges for the code block to be executed as soon as the event model is
		650	autodetected (or immediately if this has already happened).
		651
		652	If called in scalar or list context, then it creates and returns an object
		653	that automatically removes the callback again when it is destroyed. See
		654	L<Coro::BDB> for a case where this is useful.
		655
		656	=item @AnyEvent::post_detect
		657
		658	If there are any code references in this array (you can C<push> to it
		659	before or after loading AnyEvent), then they will called directly after
		660	the event loop has been chosen.
		661
		662	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		663	if it contains a true value then the event loop has already been detected,
		664	and the array will be ignored.
		665
		666	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		667
439	=back	668	=back
440		669
441	=head1 WHAT TO DO IN A MODULE	670	=head1 WHAT TO DO IN A MODULE
442		671
443	As a module author, you should C<use AnyEvent> and call AnyEvent methods	672	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
446	Be careful when you create watchers in the module body - AnyEvent will	675	Be careful when you create watchers in the module body - AnyEvent will
447	decide which event module to use as soon as the first method is called, so	676	decide which event module to use as soon as the first method is called, so
448	by calling AnyEvent in your module body you force the user of your module	677	by calling AnyEvent in your module body you force the user of your module
449	to load the event module first.	678	to load the event module first.
450		679
451	Never call C<< ->wait >> on a condition variable unless you I<know> that	680	Never call C<< ->recv >> on a condition variable unless you I<know> that
452	the C<< ->broadcast >> method has been called on it already. This is	681	the C<< ->send >> method has been called on it already. This is
453	because it will stall the whole program, and the whole point of using	682	because it will stall the whole program, and the whole point of using
454	events is to stay interactive.	683	events is to stay interactive.
455		684
456	It is fine, however, to call C<< ->wait >> when the user of your module	685	It is fine, however, to call C<< ->recv >> when the user of your module
457	requests it (i.e. if you create a http request object ad have a method	686	requests it (i.e. if you create a http request object ad have a method
458	called C<results> that returns the results, it should call C<< ->wait >>	687	called C<results> that returns the results, it should call C<< ->recv >>
459	freely, as the user of your module knows what she is doing. always).	688	freely, as the user of your module knows what she is doing. always).
460		689
461	=head1 WHAT TO DO IN THE MAIN PROGRAM	690	=head1 WHAT TO DO IN THE MAIN PROGRAM
462		691
463	There will always be a single main program - the only place that should	692	There will always be a single main program - the only place that should
…		…
465		694
466	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	695	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
467	do anything special (it does not need to be event-based) and let AnyEvent	696	do anything special (it does not need to be event-based) and let AnyEvent
468	decide which implementation to chose if some module relies on it.	697	decide which implementation to chose if some module relies on it.
469		698
470	If the main program relies on a specific event model. For example, in	699	If the main program relies on a specific event model - for example, in
471	Gtk2 programs you have to rely on the Glib module. You should load the	700	Gtk2 programs you have to rely on the Glib module - you should load the
472	event module before loading AnyEvent or any module that uses it: generally	701	event module before loading AnyEvent or any module that uses it: generally
473	speaking, you should load it as early as possible. The reason is that	702	speaking, you should load it as early as possible. The reason is that
474	modules might create watchers when they are loaded, and AnyEvent will	703	modules might create watchers when they are loaded, and AnyEvent will
475	decide on the event model to use as soon as it creates watchers, and it	704	decide on the event model to use as soon as it creates watchers, and it
476	might chose the wrong one unless you load the correct one yourself.	705	might chose the wrong one unless you load the correct one yourself.
477		706
478	You can chose to use a rather inefficient pure-perl implementation by	707	You can chose to use a pure-perl implementation by loading the
479	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	708	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
480	behaviour everywhere, but letting AnyEvent chose is generally better.	709	everywhere, but letting AnyEvent chose the model is generally better.
		710
		711	=head2 MAINLOOP EMULATION
		712
		713	Sometimes (often for short test scripts, or even standalone programs who
		714	only want to use AnyEvent), you do not want to run a specific event loop.
		715
		716	In that case, you can use a condition variable like this:
		717
		718	AnyEvent->condvar->recv;
		719
		720	This has the effect of entering the event loop and looping forever.
		721
		722	Note that usually your program has some exit condition, in which case
		723	it is better to use the "traditional" approach of storing a condition
		724	variable somewhere, waiting for it, and sending it when the program should
		725	exit cleanly.
		726
		727
		728	=head1 OTHER MODULES
		729
		730	The following is a non-exhaustive list of additional modules that use
		731	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		732	in the same program. Some of the modules come with AnyEvent, some are
		733	available via CPAN.
		734
		735	=over 4
		736
		737	=item L<AnyEvent::Util>
		738
		739	Contains various utility functions that replace often-used but blocking
		740	functions such as C<inet_aton> by event-/callback-based versions.
		741
		742	=item L<AnyEvent::Handle>
		743
		744	Provide read and write buffers and manages watchers for reads and writes.
		745
		746	=item L<AnyEvent::Socket>
		747
		748	Provides various utility functions for (internet protocol) sockets,
		749	addresses and name resolution. Also functions to create non-blocking tcp
		750	connections or tcp servers, with IPv6 and SRV record support and more.
		751
		752	=item L<AnyEvent::DNS>
		753
		754	Provides rich asynchronous DNS resolver capabilities.
		755
		756	=item L<AnyEvent::HTTPD>
		757
		758	Provides a simple web application server framework.
		759
		760	=item L<AnyEvent::FastPing>
		761
		762	The fastest ping in the west.
		763
		764	=item L<Net::IRC3>
		765
		766	AnyEvent based IRC client module family.
		767
		768	=item L<Net::XMPP2>
		769
		770	AnyEvent based XMPP (Jabber protocol) module family.
		771
		772	=item L<Net::FCP>
		773
		774	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		775	of AnyEvent.
		776
		777	=item L<Event::ExecFlow>
		778
		779	High level API for event-based execution flow control.
		780
		781	=item L<Coro>
		782
		783	Has special support for AnyEvent via L<Coro::AnyEvent>.
		784
		785	=item L<AnyEvent::AIO>, L<IO::AIO>
		786
		787	Truly asynchronous I/O, should be in the toolbox of every event
		788	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
		789	together.
		790
		791	=item L<AnyEvent::BDB>, L<BDB>
		792
		793	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
		794	IO::AIO and AnyEvent together.
		795
		796	=item L<IO::Lambda>
		797
		798	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		799
		800	=back
481		801
482	=cut	802	=cut
483		803
484	package AnyEvent;	804	package AnyEvent;
485		805
486	no warnings;	806	no warnings;
487	use strict;	807	use strict;
488		808
489	use Carp;	809	use Carp;
490		810
491	our $VERSION = '3.3';	811	our $VERSION = 4.11;
492	our $MODEL;	812	our $MODEL;
493		813
494	our $AUTOLOAD;	814	our $AUTOLOAD;
495	our @ISA;	815	our @ISA;
496		816
		817	our @REGISTRY;
		818
		819	our $WIN32;
		820
		821	BEGIN {
		822	my $win32 = ! ! ($^O =~ /mswin32/i);
		823	eval "sub WIN32(){ $win32 }";
		824	}
		825
497	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	826	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
498		827
499	our @REGISTRY;	828	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
		829
		830	{
		831	my $idx;
		832	$PROTOCOL{$_} = ++$idx
		833	for reverse split /\s,\s/,
		834	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		835	}
500		836
501	my @models = (	837	my @models = (
502	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
503	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
504	[EV:: => AnyEvent::Impl::EV::],	838	[EV:: => AnyEvent::Impl::EV::],
505	[Event:: => AnyEvent::Impl::Event::],	839	[Event:: => AnyEvent::Impl::Event::],
506	[Glib:: => AnyEvent::Impl::Glib::],
507	[Tk:: => AnyEvent::Impl::Tk::],
508	[Wx:: => AnyEvent::Impl::POE::],
509	[Prima:: => AnyEvent::Impl::POE::],
510	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	840	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
511	# everything below here will not be autoprobed as the pureperl backend should work everywhere	841	# everything below here will not be autoprobed
		842	# as the pureperl backend should work everywhere
		843	# and is usually faster
		844	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		845	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
512	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	846	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
513	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	847	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
514	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	848	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		849	[Wx:: => AnyEvent::Impl::POE::],
		850	[Prima:: => AnyEvent::Impl::POE::],
515	);	851	);
516		852
517	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	853	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		854
		855	our @post_detect;
		856
		857	sub post_detect(&) {
		858	my ($cb) = @_;
		859
		860	if ($MODEL) {
		861	$cb->();
		862
		863	1
		864	} else {
		865	push @post_detect, $cb;
		866
		867	defined wantarray
		868	? bless \$cb, "AnyEvent::Util::PostDetect"
		869	: ()
		870	}
		871	}
		872
		873	sub AnyEvent::Util::PostDetect::DESTROY {
		874	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		875	}
518		876
519	sub detect() {	877	sub detect() {
520	unless ($MODEL) {	878	unless ($MODEL) {
521	no strict 'refs';	879	no strict 'refs';
		880	local $SIG{__DIE__};
522		881
523	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	882	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
524	my $model = "AnyEvent::Impl::$1";	883	my $model = "AnyEvent::Impl::$1";
525	if (eval "require $model") {	884	if (eval "require $model") {
526	$MODEL = $model;	885	$MODEL = $model;
…		…
556	last;	915	last;
557	}	916	}
558	}	917	}
559		918
560	$MODEL	919	$MODEL
561	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.";	920	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
562	}	921	}
563	}	922	}
564		923
565	unshift @ISA, $MODEL;	924	unshift @ISA, $MODEL;
566	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	925	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		926
		927	(shift @post_detect)->() while @post_detect;
567	}	928	}
568		929
569	$MODEL	930	$MODEL
570	}	931	}
571		932
…		…
581	$class->$func (@_);	942	$class->$func (@_);
582	}	943	}
583		944
584	package AnyEvent::Base;	945	package AnyEvent::Base;
585		946
		947	# default implementation for now and time
		948
		949	use Time::HiRes ();
		950
		951	sub time { Time::HiRes::time }
		952	sub now { Time::HiRes::time }
		953
586	# default implementation for ->condvar, ->wait, ->broadcast	954	# default implementation for ->condvar
587		955
588	sub condvar {	956	sub condvar {
589	bless \my $flag, "AnyEvent::Base::CondVar"	957	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
590	}
591
592	sub AnyEvent::Base::CondVar::broadcast {
593	${$_[0]}++;
594	}
595
596	sub AnyEvent::Base::CondVar::wait {
597	AnyEvent->one_event while !${$_[0]};
598	}	958	}
599		959
600	# default implementation for ->signal	960	# default implementation for ->signal
601		961
602	our %SIG_CB;	962	our %SIG_CB;
…		…
655	or Carp::croak "required option 'pid' is missing";	1015	or Carp::croak "required option 'pid' is missing";
656		1016
657	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1017	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
658		1018
659	unless ($WNOHANG) {	1019	unless ($WNOHANG) {
660	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1020	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
661	}	1021	}
662		1022
663	unless ($CHLD_W) {	1023	unless ($CHLD_W) {
664	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1024	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
665	# child could be a zombie already, so make at least one round	1025	# child could be a zombie already, so make at least one round
…		…
675	delete $PID_CB{$pid}{$cb};	1035	delete $PID_CB{$pid}{$cb};
676	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1036	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
677		1037
678	undef $CHLD_W unless keys %PID_CB;	1038	undef $CHLD_W unless keys %PID_CB;
679	}	1039	}
		1040
		1041	package AnyEvent::CondVar;
		1042
		1043	our @ISA = AnyEvent::CondVar::Base::;
		1044
		1045	package AnyEvent::CondVar::Base;
		1046
		1047	use overload
		1048	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1049	fallback => 1;
		1050
		1051	sub _send {
		1052	# nop
		1053	}
		1054
		1055	sub send {
		1056	my $cv = shift;
		1057	$cv->{_ae_sent} = [@_];
		1058	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1059	$cv->_send;
		1060	}
		1061
		1062	sub croak {
		1063	$_[0]{_ae_croak} = $_[1];
		1064	$_[0]->send;
		1065	}
		1066
		1067	sub ready {
		1068	$_[0]{_ae_sent}
		1069	}
		1070
		1071	sub _wait {
		1072	AnyEvent->one_event while !$_[0]{_ae_sent};
		1073	}
		1074
		1075	sub recv {
		1076	$_[0]->_wait;
		1077
		1078	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1079	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1080	}
		1081
		1082	sub cb {
		1083	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1084	$_[0]{_ae_cb}
		1085	}
		1086
		1087	sub begin {
		1088	++$_[0]{_ae_counter};
		1089	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1090	}
		1091
		1092	sub end {
		1093	return if --$_[0]{_ae_counter};
		1094	&{ $_[0]{_ae_end_cb} \|\| sub { $_[0]->send } };
		1095	}
		1096
		1097	# undocumented/compatibility with pre-3.4
		1098	*broadcast = \&send;
		1099	*wait = \&_wait;
680		1100
681	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1101	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
682		1102
683	This is an advanced topic that you do not normally need to use AnyEvent in	1103	This is an advanced topic that you do not normally need to use AnyEvent in
684	a module. This section is only of use to event loop authors who want to	1104	a module. This section is only of use to event loop authors who want to
…		…
741	model it chooses.	1161	model it chooses.
742		1162
743	=item C<PERL_ANYEVENT_MODEL>	1163	=item C<PERL_ANYEVENT_MODEL>
744		1164
745	This can be used to specify the event model to be used by AnyEvent, before	1165	This can be used to specify the event model to be used by AnyEvent, before
746	autodetection and -probing kicks in. It must be a string consisting	1166	auto detection and -probing kicks in. It must be a string consisting
747	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1167	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
748	and the resulting module name is loaded and if the load was successful,	1168	and the resulting module name is loaded and if the load was successful,
749	used as event model. If it fails to load AnyEvent will proceed with	1169	used as event model. If it fails to load AnyEvent will proceed with
750	autodetection and -probing.	1170	auto detection and -probing.
751		1171
752	This functionality might change in future versions.	1172	This functionality might change in future versions.
753		1173
754	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1174	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
755	could start your program like this:	1175	could start your program like this:
756		1176
757	PERL_ANYEVENT_MODEL=Perl perl ...	1177	PERL_ANYEVENT_MODEL=Perl perl ...
		1178
		1179	=item C<PERL_ANYEVENT_PROTOCOLS>
		1180
		1181	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1182	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1183	of auto probing).
		1184
		1185	Must be set to a comma-separated list of protocols or address families,
		1186	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1187	used, and preference will be given to protocols mentioned earlier in the
		1188	list.
		1189
		1190	This variable can effectively be used for denial-of-service attacks
		1191	against local programs (e.g. when setuid), although the impact is likely
		1192	small, as the program has to handle connection errors already-
		1193
		1194	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1195	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1196	- only support IPv4, never try to resolve or contact IPv6
		1197	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1198	IPv6, but prefer IPv6 over IPv4.
		1199
		1200	=item C<PERL_ANYEVENT_EDNS0>
		1201
		1202	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1203	for DNS. This extension is generally useful to reduce DNS traffic, but
		1204	some (broken) firewalls drop such DNS packets, which is why it is off by
		1205	default.
		1206
		1207	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1208	EDNS0 in its DNS requests.
		1209
		1210	=item C<PERL_ANYEVENT_MAX_FORKS>
		1211
		1212	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1213	will create in parallel.
758		1214
759	=back	1215	=back
760		1216
761	=head1 EXAMPLE PROGRAM	1217	=head1 EXAMPLE PROGRAM
762		1218
…		…
773	poll => 'r',	1229	poll => 'r',
774	cb => sub {	1230	cb => sub {
775	warn "io event <$_[0]>\n"; # will always output <r>	1231	warn "io event <$_[0]>\n"; # will always output <r>
776	chomp (my $input = <STDIN>); # read a line	1232	chomp (my $input = <STDIN>); # read a line
777	warn "read: $input\n"; # output what has been read	1233	warn "read: $input\n"; # output what has been read
778	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1234	$cv->send if $input =~ /^q/i; # quit program if /^q/i
779	},	1235	},
780	);	1236	);
781		1237
782	my $time_watcher; # can only be used once	1238	my $time_watcher; # can only be used once
783		1239
…		…
788	});	1244	});
789	}	1245	}
790		1246
791	new_timer; # create first timer	1247	new_timer; # create first timer
792		1248
793	$cv->wait; # wait until user enters /^q/i	1249	$cv->recv; # wait until user enters /^q/i
794		1250
795	=head1 REAL-WORLD EXAMPLE	1251	=head1 REAL-WORLD EXAMPLE
796		1252
797	Consider the L<Net::FCP> module. It features (among others) the following	1253	Consider the L<Net::FCP> module. It features (among others) the following
798	API calls, which are to freenet what HTTP GET requests are to http:	1254	API calls, which are to freenet what HTTP GET requests are to http:
…		…
848	syswrite $txn->{fh}, $txn->{request}	1304	syswrite $txn->{fh}, $txn->{request}
849	or die "connection or write error";	1305	or die "connection or write error";
850	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1306	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
851		1307
852	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1308	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
853	result and signals any possible waiters that the request ahs finished:	1309	result and signals any possible waiters that the request has finished:
854		1310
855	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1311	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
856		1312
857	if (end-of-file or data complete) {	1313	if (end-of-file or data complete) {
858	$txn->{result} = $txn->{buf};	1314	$txn->{result} = $txn->{buf};
859	$txn->{finished}->broadcast;	1315	$txn->{finished}->send;
860	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1316	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
861	}	1317	}
862		1318
863	The C<result> method, finally, just waits for the finished signal (if the	1319	The C<result> method, finally, just waits for the finished signal (if the
864	request was already finished, it doesn't wait, of course, and returns the	1320	request was already finished, it doesn't wait, of course, and returns the
865	data:	1321	data:
866		1322
867	$txn->{finished}->wait;	1323	$txn->{finished}->recv;
868	return $txn->{result};	1324	return $txn->{result};
869		1325
870	The actual code goes further and collects all errors (C<die>s, exceptions)	1326	The actual code goes further and collects all errors (C<die>s, exceptions)
871	that occured during request processing. The C<result> method detects	1327	that occurred during request processing. The C<result> method detects
872	whether an exception as thrown (it is stored inside the $txn object)	1328	whether an exception as thrown (it is stored inside the $txn object)
873	and just throws the exception, which means connection errors and other	1329	and just throws the exception, which means connection errors and other
874	problems get reported tot he code that tries to use the result, not in a	1330	problems get reported tot he code that tries to use the result, not in a
875	random callback.	1331	random callback.
876		1332
…		…
907		1363
908	my $quit = AnyEvent->condvar;	1364	my $quit = AnyEvent->condvar;
909		1365
910	$fcp->txn_client_get ($url)->cb (sub {	1366	$fcp->txn_client_get ($url)->cb (sub {
911	...	1367	...
912	$quit->broadcast;	1368	$quit->send;
913	});	1369	});
914		1370
915	$quit->wait;	1371	$quit->recv;
916		1372
917		1373
918	=head1 BENCHMARKS	1374	=head1 BENCHMARKS
919		1375
920	To give you an idea of the performance and overheads that AnyEvent adds	1376	To give you an idea of the performance and overheads that AnyEvent adds
…		…
922	of various event loops I prepared some benchmarks.	1378	of various event loops I prepared some benchmarks.
923		1379
924	=head2 BENCHMARKING ANYEVENT OVERHEAD	1380	=head2 BENCHMARKING ANYEVENT OVERHEAD
925		1381
926	Here is a benchmark of various supported event models used natively and	1382	Here is a benchmark of various supported event models used natively and
927	through anyevent. The benchmark creates a lot of timers (with a zero	1383	through AnyEvent. The benchmark creates a lot of timers (with a zero
928	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1384	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
929	which it is), lets them fire exactly once and destroys them again.	1385	which it is), lets them fire exactly once and destroys them again.
930		1386
931	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1387	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
932	distribution.	1388	distribution.
…		…
949	all watchers, to avoid adding memory overhead. That means closure creation	1405	all watchers, to avoid adding memory overhead. That means closure creation
950	and memory usage is not included in the figures.	1406	and memory usage is not included in the figures.
951		1407
952	I<invoke> is the time, in microseconds, used to invoke a simple	1408	I<invoke> is the time, in microseconds, used to invoke a simple
953	callback. The callback simply counts down a Perl variable and after it was	1409	callback. The callback simply counts down a Perl variable and after it was
954	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1410	invoked "watcher" times, it would C<< ->send >> a condvar once to
955	signal the end of this phase.	1411	signal the end of this phase.
956		1412
957	I<destroy> is the time, in microseconds, that it takes to destroy a single	1413	I<destroy> is the time, in microseconds, that it takes to destroy a single
958	watcher.	1414	watcher.
959		1415
…		…
1019	file descriptor is dup()ed for each watcher. This shows that the dup()	1475	file descriptor is dup()ed for each watcher. This shows that the dup()
1020	employed by some adaptors is not a big performance issue (it does incur a	1476	employed by some adaptors is not a big performance issue (it does incur a
1021	hidden memory cost inside the kernel which is not reflected in the figures	1477	hidden memory cost inside the kernel which is not reflected in the figures
1022	above).	1478	above).
1023		1479
1024	C<POE>, regardless of underlying event loop (whether using its pure	1480	C<POE>, regardless of underlying event loop (whether using its pure perl
1025	perl select-based backend or the Event module, the POE-EV backend	1481	select-based backend or the Event module, the POE-EV backend couldn't
1026	couldn't be tested because it wasn't working) shows abysmal performance	1482	be tested because it wasn't working) shows abysmal performance and
1027	and memory usage: Watchers use almost 30 times as much memory as	1483	memory usage with AnyEvent: Watchers use almost 30 times as much memory
1028	EV watchers, and 10 times as much memory as Event (the high memory	1484	as EV watchers, and 10 times as much memory as Event (the high memory
1029	requirements are caused by requiring a session for each watcher). Watcher	1485	requirements are caused by requiring a session for each watcher). Watcher
1030	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1486	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1487	implementation.
		1488
1031	implementation. The design of the POE adaptor class in AnyEvent can not	1489	The design of the POE adaptor class in AnyEvent can not really account
1032	really account for this, as session creation overhead is small compared	1490	for the performance issues, though, as session creation overhead is
1033	to execution of the state machine, which is coded pretty optimally within	1491	small compared to execution of the state machine, which is coded pretty
1034	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1492	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1493	using multiple sessions is not a good approach, especially regarding
		1494	memory usage, even the author of POE could not come up with a faster
		1495	design).
1035		1496
1036	=head3 Summary	1497	=head3 Summary
1037		1498
1038	=over 4	1499	=over 4
1039		1500
…		…
1050		1511
1051	=back	1512	=back
1052		1513
1053	=head2 BENCHMARKING THE LARGE SERVER CASE	1514	=head2 BENCHMARKING THE LARGE SERVER CASE
1054		1515
1055	This benchmark atcually benchmarks the event loop itself. It works by	1516	This benchmark actually benchmarks the event loop itself. It works by
1056	creating a number of "servers": each server consists of a socketpair, a	1517	creating a number of "servers": each server consists of a socket pair, a
1057	timeout watcher that gets reset on activity (but never fires), and an I/O	1518	timeout watcher that gets reset on activity (but never fires), and an I/O
1058	watcher waiting for input on one side of the socket. Each time the socket	1519	watcher waiting for input on one side of the socket. Each time the socket
1059	watcher reads a byte it will write that byte to a random other "server".	1520	watcher reads a byte it will write that byte to a random other "server".
1060		1521
1061	The effect is that there will be a lot of I/O watchers, only part of which	1522	The effect is that there will be a lot of I/O watchers, only part of which
1062	are active at any one point (so there is a constant number of active	1523	are active at any one point (so there is a constant number of active
1063	fds for each loop iterstaion, but which fds these are is random). The	1524	fds for each loop iteration, but which fds these are is random). The
1064	timeout is reset each time something is read because that reflects how	1525	timeout is reset each time something is read because that reflects how
1065	most timeouts work (and puts extra pressure on the event loops).	1526	most timeouts work (and puts extra pressure on the event loops).
1066		1527
1067	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1528	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1068	(1%) are active. This mirrors the activity of large servers with many	1529	(1%) are active. This mirrors the activity of large servers with many
1069	connections, most of which are idle at any one point in time.	1530	connections, most of which are idle at any one point in time.
1070		1531
1071	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1532	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1072	distribution.	1533	distribution.
…		…
1074	=head3 Explanation of the columns	1535	=head3 Explanation of the columns
1075		1536
1076	I<sockets> is the number of sockets, and twice the number of "servers" (as	1537	I<sockets> is the number of sockets, and twice the number of "servers" (as
1077	each server has a read and write socket end).	1538	each server has a read and write socket end).
1078		1539
1079	I<create> is the time it takes to create a socketpair (which is	1540	I<create> is the time it takes to create a socket pair (which is
1080	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1541	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1081		1542
1082	I<request>, the most important value, is the time it takes to handle a	1543	I<request>, the most important value, is the time it takes to handle a
1083	single "request", that is, reading the token from the pipe and forwarding	1544	single "request", that is, reading the token from the pipe and forwarding
1084	it to another server. This includes deleting the old timeout and creating	1545	it to another server. This includes deleting the old timeout and creating
…		…
1086		1547
1087	=head3 Results	1548	=head3 Results
1088		1549
1089	name sockets create request	1550	name sockets create request
1090	EV 20000 69.01 11.16	1551	EV 20000 69.01 11.16
1091	Perl 20000 75.28 112.76	1552	Perl 20000 73.32 35.87
1092	Event 20000 212.62 257.32	1553	Event 20000 212.62 257.32
1093	Glib 20000 651.16 1896.30	1554	Glib 20000 651.16 1896.30
1094	POE 20000 349.67 12317.24 uses POE::Loop::Event	1555	POE 20000 349.67 12317.24 uses POE::Loop::Event
1095		1556
1096	=head3 Discussion	1557	=head3 Discussion
…		…
1118		1579
1119	=head3 Summary	1580	=head3 Summary
1120		1581
1121	=over 4	1582	=over 4
1122		1583
1123	=item * The pure perl implementation performs extremely well, considering	1584	=item * The pure perl implementation performs extremely well.
1124	that it uses select.
1125		1585
1126	=item * Avoid Glib or POE in large projects where performance matters.	1586	=item * Avoid Glib or POE in large projects where performance matters.
1127		1587
1128	=back	1588	=back
1129		1589
…		…
1142		1602
1143	=head3 Results	1603	=head3 Results
1144		1604
1145	name sockets create request	1605	name sockets create request
1146	EV 16 20.00 6.54	1606	EV 16 20.00 6.54
		1607	Perl 16 25.75 12.62
1147	Event 16 81.27 35.86	1608	Event 16 81.27 35.86
1148	Glib 16 32.63 15.48	1609	Glib 16 32.63 15.48
1149	Perl 16 24.62 162.37
1150	POE 16 261.87 276.28 uses POE::Loop::Event	1610	POE 16 261.87 276.28 uses POE::Loop::Event
1151		1611
1152	=head3 Discussion	1612	=head3 Discussion
1153		1613
1154	The benchmark tries to test the performance of a typical small	1614	The benchmark tries to test the performance of a typical small
…		…
1158	speed most when you have lots of watchers, not when you only have a few of	1618	speed most when you have lots of watchers, not when you only have a few of
1159	them).	1619	them).
1160		1620
1161	EV is again fastest.	1621	EV is again fastest.
1162		1622
1163	The C-based event loops Event and Glib come in second this time, as the	1623	Perl again comes second. It is noticeably faster than the C-based event
1164	overhead of running an iteration is much smaller in C than in Perl (little	1624	loops Event and Glib, although the difference is too small to really
1165	code to execute in the inner loop, and perl's function calling overhead is	1625	matter.
1166	high, and updating all the data structures is costly).
1167
1168	The pure perl event loop is much slower, but still competitive.
1169		1626
1170	POE also performs much better in this case, but is is still far behind the	1627	POE also performs much better in this case, but is is still far behind the
1171	others.	1628	others.
1172		1629
1173	=head3 Summary	1630	=head3 Summary
…		…
1181		1638
1182		1639
1183	=head1 FORK	1640	=head1 FORK
1184		1641
1185	Most event libraries are not fork-safe. The ones who are usually are	1642	Most event libraries are not fork-safe. The ones who are usually are
1186	because they are so inefficient. Only L<EV> is fully fork-aware.	1643	because they rely on inefficient but fork-safe C<select> or C<poll>
		1644	calls. Only L<EV> is fully fork-aware.
1187		1645
1188	If you have to fork, you must either do so I<before> creating your first	1646	If you have to fork, you must either do so I<before> creating your first
1189	watcher OR you must not use AnyEvent at all in the child.	1647	watcher OR you must not use AnyEvent at all in the child.
1190		1648
1191		1649
…		…
1203		1661
1204	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1662	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1205		1663
1206	use AnyEvent;	1664	use AnyEvent;
1207		1665
		1666	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1667	be used to probe what backend is used and gain other information (which is
		1668	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
		1669
1208		1670
1209	=head1 SEE ALSO	1671	=head1 SEE ALSO
1210		1672
1211	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1673	Utility functions: L<AnyEvent::Util>.
1212	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1674
		1675	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1213	L<Event::Lib>, L<Qt>, L<POE>.	1676	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1214		1677
1215	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1678	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1216	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1679	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1217	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1680	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1218	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1681	L<AnyEvent::Impl::POE>.
1219		1682
		1683	Non-blocking file handles, sockets, TCP clients and
		1684	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1685
		1686	Asynchronous DNS: L<AnyEvent::DNS>.
		1687
		1688	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1689
1220	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1690	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1221		1691
1222		1692
1223	=head1 AUTHOR	1693	=head1 AUTHOR
1224		1694
1225	Marc Lehmann <schmorp@schmorp.de>	1695	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.98 by root, Sun Apr 27 16:31:48 2008 UTC vs. Revision 1.148 by root, Sat May 31 00:40:16 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.98 by root, Sun Apr 27 16:31:48 2008 UTC vs.
Revision 1.148 by root, Sat May 31 00:40:16 2008 UTC