[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 1.158 by root, Fri Jun 6 15:35:30 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).
…		…
146	Many watchers either are used with "recursion" (repeating timers for	138	Many watchers either are used with "recursion" (repeating timers for
147	example), or need to refer to their watcher object in other ways.	139	example), or need to refer to their watcher object in other ways.
148		140
149	An any way to achieve that is this pattern:	141	An any way to achieve that is this pattern:
150		142
151	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	143	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
152	# you can use $w here, for example to undef it	144	# you can use $w here, for example to undef it
153	undef $w;	145	undef $w;
154	});	146	});
155		147
156	Note that C<my $w; $w => combination. This is necessary because in Perl,	148	Note that C<my $w; $w => combination. This is necessary because in Perl,
157	my variables are only visible after the statement in which they are	149	my variables are only visible after the statement in which they are
158	declared.	150	declared.
159		151
…		…
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
…		…
297	AnyEvent program, you I<have> to create at least one watcher before you	352	AnyEvent program, you I<have> to create at least one watcher before you
298	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	353	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
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::HTTP>
		758
		759	A simple-to-use HTTP library that is capable of making a lot of concurrent
		760	HTTP requests.
		761
		762	=item L<AnyEvent::HTTPD>
		763
		764	Provides a simple web application server framework.
		765
496	=item L<AnyEvent::FastPing>	766	=item L<AnyEvent::FastPing>
497		767
		768	The fastest ping in the west.
		769
498	=item L<Net::IRC3>	770	=item L<Net::IRC3>
499		771
		772	AnyEvent based IRC client module family.
		773
500	=item L<Net::XMPP2>	774	=item L<Net::XMPP2>
		775
		776	AnyEvent based XMPP (Jabber protocol) module family.
		777
		778	=item L<Net::FCP>
		779
		780	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		781	of AnyEvent.
		782
		783	=item L<Event::ExecFlow>
		784
		785	High level API for event-based execution flow control.
		786
		787	=item L<Coro>
		788
		789	Has special support for AnyEvent via L<Coro::AnyEvent>.
		790
		791	=item L<AnyEvent::AIO>, L<IO::AIO>
		792
		793	Truly asynchronous I/O, should be in the toolbox of every event
		794	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
		795	together.
		796
		797	=item L<AnyEvent::BDB>, L<BDB>
		798
		799	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
		800	IO::AIO and AnyEvent together.
		801
		802	=item L<IO::Lambda>
		803
		804	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
501		805
502	=back	806	=back
503		807
504	=cut	808	=cut
505		809
…		…
508	no warnings;	812	no warnings;
509	use strict;	813	use strict;
510		814
511	use Carp;	815	use Carp;
512		816
513	our $VERSION = '3.3';	817	our $VERSION = 4.151;
514	our $MODEL;	818	our $MODEL;
515		819
516	our $AUTOLOAD;	820	our $AUTOLOAD;
517	our @ISA;	821	our @ISA;
518		822
		823	our @REGISTRY;
		824
		825	our $WIN32;
		826
		827	BEGIN {
		828	my $win32 = ! ! ($^O =~ /mswin32/i);
		829	eval "sub WIN32(){ $win32 }";
		830	}
		831
519	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	832	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
520		833
521	our @REGISTRY;	834	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
		835
		836	{
		837	my $idx;
		838	$PROTOCOL{$_} = ++$idx
		839	for reverse split /\s,\s/,
		840	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		841	}
522		842
523	my @models = (	843	my @models = (
524	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
525	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
526	[EV:: => AnyEvent::Impl::EV::],	844	[EV:: => AnyEvent::Impl::EV::],
527	[Event:: => AnyEvent::Impl::Event::],	845	[Event:: => AnyEvent::Impl::Event::],
528	[Glib:: => AnyEvent::Impl::Glib::],
529	[Tk:: => AnyEvent::Impl::Tk::],
530	[Wx:: => AnyEvent::Impl::POE::],
531	[Prima:: => AnyEvent::Impl::POE::],
532	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	846	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
533	# everything below here will not be autoprobed as the pureperl backend should work everywhere	847	# everything below here will not be autoprobed
		848	# as the pureperl backend should work everywhere
		849	# and is usually faster
		850	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		851	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
534	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	852	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
535	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	853	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
536	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	854	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		855	[Wx:: => AnyEvent::Impl::POE::],
		856	[Prima:: => AnyEvent::Impl::POE::],
537	);	857	);
538		858
539	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	859	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		860
		861	our @post_detect;
		862
		863	sub post_detect(&) {
		864	my ($cb) = @_;
		865
		866	if ($MODEL) {
		867	$cb->();
		868
		869	1
		870	} else {
		871	push @post_detect, $cb;
		872
		873	defined wantarray
		874	? bless \$cb, "AnyEvent::Util::PostDetect"
		875	: ()
		876	}
		877	}
		878
		879	sub AnyEvent::Util::PostDetect::DESTROY {
		880	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		881	}
540		882
541	sub detect() {	883	sub detect() {
542	unless ($MODEL) {	884	unless ($MODEL) {
543	no strict 'refs';	885	no strict 'refs';
		886	local $SIG{__DIE__};
544		887
545	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	888	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
546	my $model = "AnyEvent::Impl::$1";	889	my $model = "AnyEvent::Impl::$1";
547	if (eval "require $model") {	890	if (eval "require $model") {
548	$MODEL = $model;	891	$MODEL = $model;
…		…
578	last;	921	last;
579	}	922	}
580	}	923	}
581		924
582	$MODEL	925	$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.";	926	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
584	}	927	}
585	}	928	}
586		929
587	unshift @ISA, $MODEL;	930	unshift @ISA, $MODEL;
588	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	931	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		932
		933	(shift @post_detect)->() while @post_detect;
589	}	934	}
590		935
591	$MODEL	936	$MODEL
592	}	937	}
593		938
…		…
603	$class->$func (@_);	948	$class->$func (@_);
604	}	949	}
605		950
606	package AnyEvent::Base;	951	package AnyEvent::Base;
607		952
		953	# default implementation for now and time
		954
		955	use Time::HiRes ();
		956
		957	sub time { Time::HiRes::time }
		958	sub now { Time::HiRes::time }
		959
608	# default implementation for ->condvar, ->wait, ->broadcast	960	# default implementation for ->condvar
609		961
610	sub condvar {	962	sub condvar {
611	bless \my $flag, "AnyEvent::Base::CondVar"	963	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	}	964	}
621		965
622	# default implementation for ->signal	966	# default implementation for ->signal
623		967
624	our %SIG_CB;	968	our %SIG_CB;
…		…
677	or Carp::croak "required option 'pid' is missing";	1021	or Carp::croak "required option 'pid' is missing";
678		1022
679	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1023	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
680		1024
681	unless ($WNOHANG) {	1025	unless ($WNOHANG) {
682	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1026	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
683	}	1027	}
684		1028
685	unless ($CHLD_W) {	1029	unless ($CHLD_W) {
686	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1030	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
687	# child could be a zombie already, so make at least one round	1031	# child could be a zombie already, so make at least one round
…		…
697	delete $PID_CB{$pid}{$cb};	1041	delete $PID_CB{$pid}{$cb};
698	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1042	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
699		1043
700	undef $CHLD_W unless keys %PID_CB;	1044	undef $CHLD_W unless keys %PID_CB;
701	}	1045	}
		1046
		1047	package AnyEvent::CondVar;
		1048
		1049	our @ISA = AnyEvent::CondVar::Base::;
		1050
		1051	package AnyEvent::CondVar::Base;
		1052
		1053	use overload
		1054	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1055	fallback => 1;
		1056
		1057	sub _send {
		1058	# nop
		1059	}
		1060
		1061	sub send {
		1062	my $cv = shift;
		1063	$cv->{_ae_sent} = [@_];
		1064	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1065	$cv->_send;
		1066	}
		1067
		1068	sub croak {
		1069	$_[0]{_ae_croak} = $_[1];
		1070	$_[0]->send;
		1071	}
		1072
		1073	sub ready {
		1074	$_[0]{_ae_sent}
		1075	}
		1076
		1077	sub _wait {
		1078	AnyEvent->one_event while !$_[0]{_ae_sent};
		1079	}
		1080
		1081	sub recv {
		1082	$_[0]->_wait;
		1083
		1084	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1085	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1086	}
		1087
		1088	sub cb {
		1089	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1090	$_[0]{_ae_cb}
		1091	}
		1092
		1093	sub begin {
		1094	++$_[0]{_ae_counter};
		1095	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1096	}
		1097
		1098	sub end {
		1099	return if --$_[0]{_ae_counter};
		1100	&{ $_[0]{_ae_end_cb} \|\| sub { $_[0]->send } };
		1101	}
		1102
		1103	# undocumented/compatibility with pre-3.4
		1104	*broadcast = \&send;
		1105	*wait = \&_wait;
702		1106
703	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1107	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
704		1108
705	This is an advanced topic that you do not normally need to use AnyEvent in	1109	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	1110	a module. This section is only of use to event loop authors who want to
…		…
763	model it chooses.	1167	model it chooses.
764		1168
765	=item C<PERL_ANYEVENT_MODEL>	1169	=item C<PERL_ANYEVENT_MODEL>
766		1170
767	This can be used to specify the event model to be used by AnyEvent, before	1171	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	1172	auto detection and -probing kicks in. It must be a string consisting
769	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1173	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,	1174	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	1175	used as event model. If it fails to load AnyEvent will proceed with
772	autodetection and -probing.	1176	auto detection and -probing.
773		1177
774	This functionality might change in future versions.	1178	This functionality might change in future versions.
775		1179
776	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1180	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
777	could start your program like this:	1181	could start your program like this:
778		1182
779	PERL_ANYEVENT_MODEL=Perl perl ...	1183	PERL_ANYEVENT_MODEL=Perl perl ...
		1184
		1185	=item C<PERL_ANYEVENT_PROTOCOLS>
		1186
		1187	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1188	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1189	of auto probing).
		1190
		1191	Must be set to a comma-separated list of protocols or address families,
		1192	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1193	used, and preference will be given to protocols mentioned earlier in the
		1194	list.
		1195
		1196	This variable can effectively be used for denial-of-service attacks
		1197	against local programs (e.g. when setuid), although the impact is likely
		1198	small, as the program has to handle connection errors already-
		1199
		1200	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1201	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1202	- only support IPv4, never try to resolve or contact IPv6
		1203	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1204	IPv6, but prefer IPv6 over IPv4.
		1205
		1206	=item C<PERL_ANYEVENT_EDNS0>
		1207
		1208	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1209	for DNS. This extension is generally useful to reduce DNS traffic, but
		1210	some (broken) firewalls drop such DNS packets, which is why it is off by
		1211	default.
		1212
		1213	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1214	EDNS0 in its DNS requests.
		1215
		1216	=item C<PERL_ANYEVENT_MAX_FORKS>
		1217
		1218	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1219	will create in parallel.
780		1220
781	=back	1221	=back
782		1222
783	=head1 EXAMPLE PROGRAM	1223	=head1 EXAMPLE PROGRAM
784		1224
…		…
795	poll => 'r',	1235	poll => 'r',
796	cb => sub {	1236	cb => sub {
797	warn "io event <$_[0]>\n"; # will always output <r>	1237	warn "io event <$_[0]>\n"; # will always output <r>
798	chomp (my $input = <STDIN>); # read a line	1238	chomp (my $input = <STDIN>); # read a line
799	warn "read: $input\n"; # output what has been read	1239	warn "read: $input\n"; # output what has been read
800	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1240	$cv->send if $input =~ /^q/i; # quit program if /^q/i
801	},	1241	},
802	);	1242	);
803		1243
804	my $time_watcher; # can only be used once	1244	my $time_watcher; # can only be used once
805		1245
…		…
810	});	1250	});
811	}	1251	}
812		1252
813	new_timer; # create first timer	1253	new_timer; # create first timer
814		1254
815	$cv->wait; # wait until user enters /^q/i	1255	$cv->recv; # wait until user enters /^q/i
816		1256
817	=head1 REAL-WORLD EXAMPLE	1257	=head1 REAL-WORLD EXAMPLE
818		1258
819	Consider the L<Net::FCP> module. It features (among others) the following	1259	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:	1260	API calls, which are to freenet what HTTP GET requests are to http:
…		…
870	syswrite $txn->{fh}, $txn->{request}	1310	syswrite $txn->{fh}, $txn->{request}
871	or die "connection or write error";	1311	or die "connection or write error";
872	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1312	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
873		1313
874	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1314	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:	1315	result and signals any possible waiters that the request has finished:
876		1316
877	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1317	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
878		1318
879	if (end-of-file or data complete) {	1319	if (end-of-file or data complete) {
880	$txn->{result} = $txn->{buf};	1320	$txn->{result} = $txn->{buf};
881	$txn->{finished}->broadcast;	1321	$txn->{finished}->send;
882	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1322	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
883	}	1323	}
884		1324
885	The C<result> method, finally, just waits for the finished signal (if the	1325	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	1326	request was already finished, it doesn't wait, of course, and returns the
887	data:	1327	data:
888		1328
889	$txn->{finished}->wait;	1329	$txn->{finished}->recv;
890	return $txn->{result};	1330	return $txn->{result};
891		1331
892	The actual code goes further and collects all errors (C<die>s, exceptions)	1332	The actual code goes further and collects all errors (C<die>s, exceptions)
893	that occured during request processing. The C<result> method detects	1333	that occurred during request processing. The C<result> method detects
894	whether an exception as thrown (it is stored inside the $txn object)	1334	whether an exception as thrown (it is stored inside the $txn object)
895	and just throws the exception, which means connection errors and other	1335	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	1336	problems get reported tot he code that tries to use the result, not in a
897	random callback.	1337	random callback.
898		1338
…		…
929		1369
930	my $quit = AnyEvent->condvar;	1370	my $quit = AnyEvent->condvar;
931		1371
932	$fcp->txn_client_get ($url)->cb (sub {	1372	$fcp->txn_client_get ($url)->cb (sub {
933	...	1373	...
934	$quit->broadcast;	1374	$quit->send;
935	});	1375	});
936		1376
937	$quit->wait;	1377	$quit->recv;
938		1378
939		1379
940	=head1 BENCHMARKS	1380	=head1 BENCHMARKS
941		1381
942	To give you an idea of the performance and overheads that AnyEvent adds	1382	To give you an idea of the performance and overheads that AnyEvent adds
…		…
944	of various event loops I prepared some benchmarks.	1384	of various event loops I prepared some benchmarks.
945		1385
946	=head2 BENCHMARKING ANYEVENT OVERHEAD	1386	=head2 BENCHMARKING ANYEVENT OVERHEAD
947		1387
948	Here is a benchmark of various supported event models used natively and	1388	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	1389	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,	1390	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.	1391	which it is), lets them fire exactly once and destroys them again.
952		1392
953	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1393	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
954	distribution.	1394	distribution.
…		…
971	all watchers, to avoid adding memory overhead. That means closure creation	1411	all watchers, to avoid adding memory overhead. That means closure creation
972	and memory usage is not included in the figures.	1412	and memory usage is not included in the figures.
973		1413
974	I<invoke> is the time, in microseconds, used to invoke a simple	1414	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	1415	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	1416	invoked "watcher" times, it would C<< ->send >> a condvar once to
977	signal the end of this phase.	1417	signal the end of this phase.
978		1418
979	I<destroy> is the time, in microseconds, that it takes to destroy a single	1419	I<destroy> is the time, in microseconds, that it takes to destroy a single
980	watcher.	1420	watcher.
981		1421
…		…
1041	file descriptor is dup()ed for each watcher. This shows that the dup()	1481	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	1482	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	1483	hidden memory cost inside the kernel which is not reflected in the figures
1044	above).	1484	above).
1045		1485
1046	C<POE>, regardless of underlying event loop (whether using its pure	1486	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	1487	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	1488	be tested because it wasn't working) shows abysmal performance and
1049	and memory usage: Watchers use almost 30 times as much memory as	1489	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	1490	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	1491	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	1492	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1493	implementation.
		1494
1053	implementation. The design of the POE adaptor class in AnyEvent can not	1495	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	1496	for the performance issues, though, as session creation overhead is
1055	to execution of the state machine, which is coded pretty optimally within	1497	small compared to execution of the state machine, which is coded pretty
1056	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1498	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1499	using multiple sessions is not a good approach, especially regarding
		1500	memory usage, even the author of POE could not come up with a faster
		1501	design).
1057		1502
1058	=head3 Summary	1503	=head3 Summary
1059		1504
1060	=over 4	1505	=over 4
1061		1506
…		…
1072		1517
1073	=back	1518	=back
1074		1519
1075	=head2 BENCHMARKING THE LARGE SERVER CASE	1520	=head2 BENCHMARKING THE LARGE SERVER CASE
1076		1521
1077	This benchmark atcually benchmarks the event loop itself. It works by	1522	This benchmark actually benchmarks the event loop itself. It works by
1078	creating a number of "servers": each server consists of a socketpair, a	1523	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	1524	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	1525	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".	1526	watcher reads a byte it will write that byte to a random other "server".
1082		1527
1083	The effect is that there will be a lot of I/O watchers, only part of which	1528	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	1529	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	1530	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	1531	timeout is reset each time something is read because that reflects how
1087	most timeouts work (and puts extra pressure on the event loops).	1532	most timeouts work (and puts extra pressure on the event loops).
1088		1533
1089	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1534	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	1535	(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.	1536	connections, most of which are idle at any one point in time.
1092		1537
1093	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1538	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1094	distribution.	1539	distribution.
…		…
1096	=head3 Explanation of the columns	1541	=head3 Explanation of the columns
1097		1542
1098	I<sockets> is the number of sockets, and twice the number of "servers" (as	1543	I<sockets> is the number of sockets, and twice the number of "servers" (as
1099	each server has a read and write socket end).	1544	each server has a read and write socket end).
1100		1545
1101	I<create> is the time it takes to create a socketpair (which is	1546	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.	1547	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1103		1548
1104	I<request>, the most important value, is the time it takes to handle a	1549	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	1550	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	1551	it to another server. This includes deleting the old timeout and creating
…		…
1140		1585
1141	=head3 Summary	1586	=head3 Summary
1142		1587
1143	=over 4	1588	=over 4
1144		1589
1145	=item * The pure perl implementation performs extremely well, considering	1590	=item * The pure perl implementation performs extremely well.
1146	that it uses select.
1147		1591
1148	=item * Avoid Glib or POE in large projects where performance matters.	1592	=item * Avoid Glib or POE in large projects where performance matters.
1149		1593
1150	=back	1594	=back
1151		1595
…		…
1180	speed most when you have lots of watchers, not when you only have a few of	1624	speed most when you have lots of watchers, not when you only have a few of
1181	them).	1625	them).
1182		1626
1183	EV is again fastest.	1627	EV is again fastest.
1184		1628
1185	The C-based event loops Event and Glib come in second this time, as the	1629	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	1630	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	1631	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		1632
1192	POE also performs much better in this case, but is is still far behind the	1633	POE also performs much better in this case, but is is still far behind the
1193	others.	1634	others.
1194		1635
1195	=head3 Summary	1636	=head3 Summary
…		…
1203		1644
1204		1645
1205	=head1 FORK	1646	=head1 FORK
1206		1647
1207	Most event libraries are not fork-safe. The ones who are usually are	1648	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.	1649	because they rely on inefficient but fork-safe C<select> or C<poll>
		1650	calls. Only L<EV> is fully fork-aware.
1209		1651
1210	If you have to fork, you must either do so I<before> creating your first	1652	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.	1653	watcher OR you must not use AnyEvent at all in the child.
1212		1654
1213		1655
…		…
1221	specified in the variable.	1663	specified in the variable.
1222		1664
1223	You can make AnyEvent completely ignore this variable by deleting it	1665	You can make AnyEvent completely ignore this variable by deleting it
1224	before the first watcher gets created, e.g. with a C<BEGIN> block:	1666	before the first watcher gets created, e.g. with a C<BEGIN> block:
1225		1667
1226	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1668	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1227		1669
1228	use AnyEvent;	1670	use AnyEvent;
		1671
		1672	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1673	be used to probe what backend is used and gain other information (which is
		1674	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
		1675
		1676
		1677	=head1 BUGS
		1678
		1679	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1680	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1681	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1682	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1683	pronounced).
1229		1684
1230		1685
1231	=head1 SEE ALSO	1686	=head1 SEE ALSO
1232		1687
1233	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1688	Utility functions: L<AnyEvent::Util>.
1234	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1689
		1690	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1235	L<Event::Lib>, L<Qt>, L<POE>.	1691	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1236		1692
1237	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1693	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1238	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1694	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>,	1695	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1240	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1696	L<AnyEvent::Impl::POE>.
1241		1697
		1698	Non-blocking file handles, sockets, TCP clients and
		1699	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1700
		1701	Asynchronous DNS: L<AnyEvent::DNS>.
		1702
		1703	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1704
1242	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1705	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1243		1706
1244		1707
1245	=head1 AUTHOR	1708	=head1 AUTHOR
1246		1709
1247	Marc Lehmann <schmorp@schmorp.de>	1710	Marc Lehmann <schmorp@schmorp.de>
1248	http://home.schmorp.de/	1711	http://home.schmorp.de/
1249		1712
1250	=cut	1713	=cut
1251		1714
1252	1	1715	1
1253		1716

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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 1.158 by root, Fri Jun 6 15:35:30 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 1.158 by root, Fri Jun 6 15:35:30 2008 UTC