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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.100 by elmex, Sun Apr 27 19:15:43 2008 UTC vs.
Revision 1.149 by root, Sat May 31 01:41:22 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, 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.
376		605
377	=back	606	=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	$result_ready->wait;
396		607
397	=head1 GLOBAL VARIABLES AND FUNCTIONS	608	=head1 GLOBAL VARIABLES AND FUNCTIONS
398		609
399	=over 4	610	=over 4
400		611
…		…
406	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	617	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
407	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	618	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
408		619
409	The known classes so far are:	620	The known classes so far are:
410		621
411	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
412	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
413	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	622	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
414	AnyEvent::Impl::Event based on Event, second best choice.	623	AnyEvent::Impl::Event based on Event, second best choice.
		624	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
415	AnyEvent::Impl::Glib based on Glib, third-best choice.	625	AnyEvent::Impl::Glib based on Glib, third-best choice.
416	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
417	AnyEvent::Impl::Tk based on Tk, very bad choice.	626	AnyEvent::Impl::Tk based on Tk, very bad choice.
418	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	627	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
419	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	628	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
420	AnyEvent::Impl::POE based on POE, not generic enough for full support.	629	AnyEvent::Impl::POE based on POE, not generic enough for full support.
421		630
…		…
434	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	643	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
435	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
436	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
437	runtime.	646	runtime.
438		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
439	=back	669	=back
440		670
441	=head1 WHAT TO DO IN A MODULE	671	=head1 WHAT TO DO IN A MODULE
442		672
443	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
…		…
446	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
447	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
448	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
449	to load the event module first.	679	to load the event module first.
450		680
451	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
452	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
453	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
454	events is to stay interactive.	684	events is to stay interactive.
455		685
456	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
457	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
458	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 >>
459	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).
460		690
461	=head1 WHAT TO DO IN THE MAIN PROGRAM	691	=head1 WHAT TO DO IN THE MAIN PROGRAM
462		692
463	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
…		…
465		695
466	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
467	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
468	decide which implementation to chose if some module relies on it.	698	decide which implementation to chose if some module relies on it.
469		699
470	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
471	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
472	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
473	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
474	modules might create watchers when they are loaded, and AnyEvent will	704	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	705	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.	706	might chose the wrong one unless you load the correct one yourself.
477		707
478	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
479	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	709	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
480	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
481		728
482	=head1 OTHER MODULES	729	=head1 OTHER MODULES
483		730
484	L<AnyEvent> itself comes with useful utility modules:	731	The following is a non-exhaustive list of additional modules that use
485		732	AnyEvent and can therefore be mixed easily with other AnyEvent modules
486	To make it easier to do non-blocking IO the modules L<AnyEvent::Handle>	733	in the same program. Some of the modules come with AnyEvent, some are
487	and L<AnyEvent::Socket> are provided. L<AnyEvent::Handle> provides	734	available via CPAN.
488	read and write buffers and manages watchers for reads and writes.
489	L<AnyEvent::Socket> provides means to do non-blocking connects.
490
491	Aside from those there are these modules that support AnyEvent (and use it
492	for non-blocking IO):
493		735
494	=over 4	736	=over 4
495		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
496	=item L<AnyEvent::FastPing>	761	=item L<AnyEvent::FastPing>
497		762
		763	The fastest ping in the west.
		764
498	=item L<Net::IRC3>	765	=item L<Net::IRC3>
499		766
		767	AnyEvent based IRC client module family.
		768
500	=item L<Net::XMPP2>	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.
501		800
502	=back	801	=back
503		802
504	=cut	803	=cut
505		804
…		…
508	no warnings;	807	no warnings;
509	use strict;	808	use strict;
510		809
511	use Carp;	810	use Carp;
512		811
513	our $VERSION = '3.3';	812	our $VERSION = 4.11;
514	our $MODEL;	813	our $MODEL;
515		814
516	our $AUTOLOAD;	815	our $AUTOLOAD;
517	our @ISA;	816	our @ISA;
518		817
		818	our @REGISTRY;
		819
		820	our $WIN32;
		821
		822	BEGIN {
		823	my $win32 = ! ! ($^O =~ /mswin32/i);
		824	eval "sub WIN32(){ $win32 }";
		825	}
		826
519	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	827	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
520		828
521	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	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		836	}
522		837
523	my @models = (	838	my @models = (
524	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
525	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
526	[EV:: => AnyEvent::Impl::EV::],	839	[EV:: => AnyEvent::Impl::EV::],
527	[Event:: => AnyEvent::Impl::Event::],	840	[Event:: => AnyEvent::Impl::Event::],
528	[Glib:: => AnyEvent::Impl::Glib::],
529	[Tk:: => AnyEvent::Impl::Tk::],
530	[Wx:: => AnyEvent::Impl::POE::],
531	[Prima:: => AnyEvent::Impl::POE::],
532	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	841	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
533	# everything below here will not be autoprobed as the pureperl backend should work everywhere	842	# everything below here will not be autoprobed
		843	# as the pureperl backend should work everywhere
		844	# and is usually faster
		845	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		846	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
534	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	847	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
535	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	848	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
536	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	849	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		850	[Wx:: => AnyEvent::Impl::POE::],
		851	[Prima:: => AnyEvent::Impl::POE::],
537	);	852	);
538		853
539	our %method = map +($_ => 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	}
540		877
541	sub detect() {	878	sub detect() {
542	unless ($MODEL) {	879	unless ($MODEL) {
543	no strict 'refs';	880	no strict 'refs';
		881	local $SIG{__DIE__};
544		882
545	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	883	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
546	my $model = "AnyEvent::Impl::$1";	884	my $model = "AnyEvent::Impl::$1";
547	if (eval "require $model") {	885	if (eval "require $model") {
548	$MODEL = $model;	886	$MODEL = $model;
…		…
578	last;	916	last;
579	}	917	}
580	}	918	}
581		919
582	$MODEL	920	$MODEL
583	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.";
584	}	922	}
585	}	923	}
586		924
587	unshift @ISA, $MODEL;	925	unshift @ISA, $MODEL;
588	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	926	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		927
		928	(shift @post_detect)->() while @post_detect;
589	}	929	}
590		930
591	$MODEL	931	$MODEL
592	}	932	}
593		933
…		…
603	$class->$func (@_);	943	$class->$func (@_);
604	}	944	}
605		945
606	package AnyEvent::Base;	946	package AnyEvent::Base;
607		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
608	# default implementation for ->condvar, ->wait, ->broadcast	955	# default implementation for ->condvar
609		956
610	sub condvar {	957	sub condvar {
611	bless \my $flag, "AnyEvent::Base::CondVar"	958	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
612	}
613
614	sub AnyEvent::Base::CondVar::broadcast {
615	${$_[0]}++;
616	}
617
618	sub AnyEvent::Base::CondVar::wait {
619	AnyEvent->one_event while !${$_[0]};
620	}	959	}
621		960
622	# default implementation for ->signal	961	# default implementation for ->signal
623		962
624	our %SIG_CB;	963	our %SIG_CB;
…		…
677	or Carp::croak "required option 'pid' is missing";	1016	or Carp::croak "required option 'pid' is missing";
678		1017
679	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1018	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
680		1019
681	unless ($WNOHANG) {	1020	unless ($WNOHANG) {
682	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1021	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
683	}	1022	}
684		1023
685	unless ($CHLD_W) {	1024	unless ($CHLD_W) {
686	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1025	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
687	# 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
…		…
697	delete $PID_CB{$pid}{$cb};	1036	delete $PID_CB{$pid}{$cb};
698	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1037	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
699		1038
700	undef $CHLD_W unless keys %PID_CB;	1039	undef $CHLD_W unless keys %PID_CB;
701	}	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;
702		1101
703	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1102	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
704		1103
705	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
706	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
…		…
763	model it chooses.	1162	model it chooses.
764		1163
765	=item C<PERL_ANYEVENT_MODEL>	1164	=item C<PERL_ANYEVENT_MODEL>
766		1165
767	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
768	autodetection and -probing kicks in. It must be a string consisting	1167	auto detection and -probing kicks in. It must be a string consisting
769	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1168	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
770	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,
771	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
772	autodetection and -probing.	1171	auto detection and -probing.
773		1172
774	This functionality might change in future versions.	1173	This functionality might change in future versions.
775		1174
776	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
777	could start your program like this:	1176	could start your program like this:
778		1177
779	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.
780		1215
781	=back	1216	=back
782		1217
783	=head1 EXAMPLE PROGRAM	1218	=head1 EXAMPLE PROGRAM
784		1219
…		…
795	poll => 'r',	1230	poll => 'r',
796	cb => sub {	1231	cb => sub {
797	warn "io event <$_[0]>\n"; # will always output <r>	1232	warn "io event <$_[0]>\n"; # will always output <r>
798	chomp (my $input = <STDIN>); # read a line	1233	chomp (my $input = <STDIN>); # read a line
799	warn "read: $input\n"; # output what has been read	1234	warn "read: $input\n"; # output what has been read
800	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1235	$cv->send if $input =~ /^q/i; # quit program if /^q/i
801	},	1236	},
802	);	1237	);
803		1238
804	my $time_watcher; # can only be used once	1239	my $time_watcher; # can only be used once
805		1240
…		…
810	});	1245	});
811	}	1246	}
812		1247
813	new_timer; # create first timer	1248	new_timer; # create first timer
814		1249
815	$cv->wait; # wait until user enters /^q/i	1250	$cv->recv; # wait until user enters /^q/i
816		1251
817	=head1 REAL-WORLD EXAMPLE	1252	=head1 REAL-WORLD EXAMPLE
818		1253
819	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
820	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:
…		…
870	syswrite $txn->{fh}, $txn->{request}	1305	syswrite $txn->{fh}, $txn->{request}
871	or die "connection or write error";	1306	or die "connection or write error";
872	$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 });
873		1308
874	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
875	result and signals any possible waiters that the request ahs finished:	1310	result and signals any possible waiters that the request has finished:
876		1311
877	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1312	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
878		1313
879	if (end-of-file or data complete) {	1314	if (end-of-file or data complete) {
880	$txn->{result} = $txn->{buf};	1315	$txn->{result} = $txn->{buf};
881	$txn->{finished}->broadcast;	1316	$txn->{finished}->send;
882	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1317	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
883	}	1318	}
884		1319
885	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
886	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
887	data:	1322	data:
888		1323
889	$txn->{finished}->wait;	1324	$txn->{finished}->recv;
890	return $txn->{result};	1325	return $txn->{result};
891		1326
892	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)
893	that occured during request processing. The C<result> method detects	1328	that occurred during request processing. The C<result> method detects
894	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)
895	and just throws the exception, which means connection errors and other	1330	and just throws the exception, which means connection errors and other
896	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
897	random callback.	1332	random callback.
898		1333
…		…
929		1364
930	my $quit = AnyEvent->condvar;	1365	my $quit = AnyEvent->condvar;
931		1366
932	$fcp->txn_client_get ($url)->cb (sub {	1367	$fcp->txn_client_get ($url)->cb (sub {
933	...	1368	...
934	$quit->broadcast;	1369	$quit->send;
935	});	1370	});
936		1371
937	$quit->wait;	1372	$quit->recv;
938		1373
939		1374
940	=head1 BENCHMARKS	1375	=head1 BENCHMARKS
941		1376
942	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
…		…
944	of various event loops I prepared some benchmarks.	1379	of various event loops I prepared some benchmarks.
945		1380
946	=head2 BENCHMARKING ANYEVENT OVERHEAD	1381	=head2 BENCHMARKING ANYEVENT OVERHEAD
947		1382
948	Here is a benchmark of various supported event models used natively and	1383	Here is a benchmark of various supported event models used natively and
949	through anyevent. The benchmark creates a lot of timers (with a zero	1384	through AnyEvent. The benchmark creates a lot of timers (with a zero
950	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1385	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
951	which it is), lets them fire exactly once and destroys them again.	1386	which it is), lets them fire exactly once and destroys them again.
952		1387
953	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1388	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
954	distribution.	1389	distribution.
…		…
971	all watchers, to avoid adding memory overhead. That means closure creation	1406	all watchers, to avoid adding memory overhead. That means closure creation
972	and memory usage is not included in the figures.	1407	and memory usage is not included in the figures.
973		1408
974	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
975	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
976	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1411	invoked "watcher" times, it would C<< ->send >> a condvar once to
977	signal the end of this phase.	1412	signal the end of this phase.
978		1413
979	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
980	watcher.	1415	watcher.
981		1416
…		…
1041	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()
1042	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
1043	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
1044	above).	1479	above).
1045		1480
1046	C<POE>, regardless of underlying event loop (whether using its pure	1481	C<POE>, regardless of underlying event loop (whether using its pure perl
1047	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
1048	couldn't be tested because it wasn't working) shows abysmal performance	1483	be tested because it wasn't working) shows abysmal performance and
1049	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
1050	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
1051	requirements are caused by requiring a session for each watcher). Watcher	1486	requirements are caused by requiring a session for each watcher). Watcher
1052	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
1053	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
1054	really account for this, as session creation overhead is small compared	1491	for the performance issues, though, as session creation overhead is
1055	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
1056	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).
1057		1497
1058	=head3 Summary	1498	=head3 Summary
1059		1499
1060	=over 4	1500	=over 4
1061		1501
…		…
1072		1512
1073	=back	1513	=back
1074		1514
1075	=head2 BENCHMARKING THE LARGE SERVER CASE	1515	=head2 BENCHMARKING THE LARGE SERVER CASE
1076		1516
1077	This benchmark atcually benchmarks the event loop itself. It works by	1517	This benchmark actually benchmarks the event loop itself. It works by
1078	creating a number of "servers": each server consists of a socketpair, a	1518	creating a number of "servers": each server consists of a socket pair, a
1079	timeout watcher that gets reset on activity (but never fires), and an I/O	1519	timeout watcher that gets reset on activity (but never fires), and an I/O
1080	watcher waiting for input on one side of the socket. Each time the socket	1520	watcher waiting for input on one side of the socket. Each time the socket
1081	watcher reads a byte it will write that byte to a random other "server".	1521	watcher reads a byte it will write that byte to a random other "server".
1082		1522
1083	The effect is that there will be a lot of I/O watchers, only part of which	1523	The effect is that there will be a lot of I/O watchers, only part of which
1084	are active at any one point (so there is a constant number of active	1524	are active at any one point (so there is a constant number of active
1085	fds for each loop iterstaion, but which fds these are is random). The	1525	fds for each loop iteration, but which fds these are is random). The
1086	timeout is reset each time something is read because that reflects how	1526	timeout is reset each time something is read because that reflects how
1087	most timeouts work (and puts extra pressure on the event loops).	1527	most timeouts work (and puts extra pressure on the event loops).
1088		1528
1089	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1529	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1090	(1%) are active. This mirrors the activity of large servers with many	1530	(1%) are active. This mirrors the activity of large servers with many
1091	connections, most of which are idle at any one point in time.	1531	connections, most of which are idle at any one point in time.
1092		1532
1093	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1533	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1094	distribution.	1534	distribution.
…		…
1096	=head3 Explanation of the columns	1536	=head3 Explanation of the columns
1097		1537
1098	I<sockets> is the number of sockets, and twice the number of "servers" (as	1538	I<sockets> is the number of sockets, and twice the number of "servers" (as
1099	each server has a read and write socket end).	1539	each server has a read and write socket end).
1100		1540
1101	I<create> is the time it takes to create a socketpair (which is	1541	I<create> is the time it takes to create a socket pair (which is
1102	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1542	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1103		1543
1104	I<request>, the most important value, is the time it takes to handle a	1544	I<request>, the most important value, is the time it takes to handle a
1105	single "request", that is, reading the token from the pipe and forwarding	1545	single "request", that is, reading the token from the pipe and forwarding
1106	it to another server. This includes deleting the old timeout and creating	1546	it to another server. This includes deleting the old timeout and creating
…		…
1140		1580
1141	=head3 Summary	1581	=head3 Summary
1142		1582
1143	=over 4	1583	=over 4
1144		1584
1145	=item * The pure perl implementation performs extremely well, considering	1585	=item * The pure perl implementation performs extremely well.
1146	that it uses select.
1147		1586
1148	=item * Avoid Glib or POE in large projects where performance matters.	1587	=item * Avoid Glib or POE in large projects where performance matters.
1149		1588
1150	=back	1589	=back
1151		1590
…		…
1180	speed most when you have lots of watchers, not when you only have a few of	1619	speed most when you have lots of watchers, not when you only have a few of
1181	them).	1620	them).
1182		1621
1183	EV is again fastest.	1622	EV is again fastest.
1184		1623
1185	The C-based event loops Event and Glib come in second this time, as the	1624	Perl again comes second. It is noticeably faster than the C-based event
1186	overhead of running an iteration is much smaller in C than in Perl (little	1625	loops Event and Glib, although the difference is too small to really
1187	code to execute in the inner loop, and perl's function calling overhead is	1626	matter.
1188	high, and updating all the data structures is costly).
1189
1190	The pure perl event loop is much slower, but still competitive.
1191		1627
1192	POE also performs much better in this case, but is is still far behind the	1628	POE also performs much better in this case, but is is still far behind the
1193	others.	1629	others.
1194		1630
1195	=head3 Summary	1631	=head3 Summary
…		…
1203		1639
1204		1640
1205	=head1 FORK	1641	=head1 FORK
1206		1642
1207	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
1208	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.
1209		1646
1210	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
1211	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.
1212		1649
1213		1650
…		…
1225		1662
1226	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1663	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1227		1664
1228	use AnyEvent;	1665	use AnyEvent;
1229		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).
		1670
1230		1671
1231	=head1 SEE ALSO	1672	=head1 SEE ALSO
1232		1673
1233	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1674	Utility functions: L<AnyEvent::Util>.
1234	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>,
1235	L<Event::Lib>, L<Qt>, L<POE>.	1677	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1236		1678
1237	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1679	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1238	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>,
1239	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1681	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1240	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1682	L<AnyEvent::Impl::POE>.
1241		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
1242	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1691	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1243		1692
1244		1693
1245	=head1 AUTHOR	1694	=head1 AUTHOR
1246		1695
1247	Marc Lehmann <schmorp@schmorp.de>	1696	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.100 by elmex, Sun Apr 27 19:15:43 2008 UTC vs. Revision 1.149 by root, Sat May 31 01:41:22 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.100 by elmex, Sun Apr 27 19:15:43 2008 UTC vs.
Revision 1.149 by root, Sat May 31 01:41:22 2008 UTC