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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.101 by root, Sun Apr 27 19:36:55 2008 UTC vs.
Revision 1.155 by root, Fri Jun 6 07:07:01 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		82
71	=head1 DESCRIPTION	83	=head1 DESCRIPTION
72		84
…		…
78	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>
79	module.	91	module.
80		92
81	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
82	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
83	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	95	following modules is already loaded: L<EV>,
84	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>,
85	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
86	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
87	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
88	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
…		…
102	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
103	use AnyEvent so their modules work together with others seamlessly...	115	use AnyEvent so their modules work together with others seamlessly...
104		116
105	The pure-perl implementation of AnyEvent is called	117	The pure-perl implementation of AnyEvent is called
106	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
107	explicitly.	119	explicitly and enjoy the high availability of that event loop :)
108		120
109	=head1 WATCHERS	121	=head1 WATCHERS
110		122
111	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
112	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
113	the callback to call, the filehandle to watch, etc.	125	the callback to call, the file handle to watch, etc.
114		126
115	These watchers are normal Perl objects with normal Perl lifetime. After	127	These watchers are normal Perl objects with normal Perl lifetime. After
116	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
117	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
118	is in control).	130	is in control).
…		…
126	Many watchers either are used with "recursion" (repeating timers for	138	Many watchers either are used with "recursion" (repeating timers for
127	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.
128		140
129	An any way to achieve that is this pattern:	141	An any way to achieve that is this pattern:
130		142
131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	143	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
132	# you can use $w here, for example to undef it	144	# you can use $w here, for example to undef it
133	undef $w;	145	undef $w;
134	});	146	});
135		147
136	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,
137	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
138	declared.	150	declared.
139		151
…		…
227	timers.	239	timers.
228		240
229	AnyEvent always prefers relative timers, if available, matching the	241	AnyEvent always prefers relative timers, if available, matching the
230	AnyEvent API.	242	AnyEvent API.
231		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
232	=head2 SIGNAL WATCHERS	307	=head2 SIGNAL WATCHERS
233		308
234	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
235	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
236	be invoked whenever a signal occurs.	311	be invoked whenever a signal occurs.
237		312
238	Although the callback might get passed parameters, their value and	313	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	314	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	315	callbacks cannot use arguments passed to signal watcher callbacks.
241		316
242	Multiple signal occurances can be clumped together into one callback	317	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	318	invocation, and callback invocation will be synchronous. Synchronous means
244	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,
245	but it is guarenteed not to interrupt any other callbacks.	320	but it is guaranteed not to interrupt any other callbacks.
246		321
247	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
248	between multiple watchers.	323	between multiple watchers.
249		324
250	This watcher might use C<%SIG>, so programs overwriting those signals	325	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
277	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
278	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	353	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
279		354
280	Example: fork a process and wait for it	355	Example: fork a process and wait for it
281		356
282	my $done = AnyEvent->condvar;	357	my $done = AnyEvent->condvar;
283		358
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	359	my $pid = fork or exit 5;
287		360
288	my $w = AnyEvent->child (	361	my $w = AnyEvent->child (
289	pid => $pid,	362	pid => $pid,
290	cb => sub {	363	cb => sub {
291	my ($pid, $status) = @_;	364	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	365	warn "pid $pid exited with status $status";
293	$done->broadcast;	366	$done->send;
294	},	367	},
295	);	368	);
296		369
297	# do something else, then wait for process exit	370	# do something else, then wait for process exit
298	$done->wait;	371	$done->recv;
299		372
300	=head2 CONDITION VARIABLES	373	=head2 CONDITION VARIABLES
301		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
302	Condition variables can be created by calling the C<< AnyEvent->condvar >>	385	Condition variables can be created by calling the C<< AnyEvent->condvar
303	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.
304		389
305	A condition variable waits for a condition - precisely that the C<<	390	After creation, the condition variable is "false" until it becomes "true"
306	->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).
307		394
308	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,
309	example, if you write a module that does asynchronous http requests,	403	for example, if you write a module that does asynchronous http requests,
310	then a condition variable would be the ideal candidate to signal the	404	then a condition variable would be the ideal candidate to signal the
311	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.
312		407
313	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,
314	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
315	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
316	->broadcast >> the "quit" event.	411	button of your app, which would C<< ->send >> the "quit" event.
317		412
318	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
319	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
320	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
321	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,
322	as this asks for trouble.	417	as this asks for trouble.
323		418
324	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.
325		460
326	=over 4	461	=over 4
327		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
328	=item $cv->wait	494	=item $cv->end
329		495
330	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 $cv->recv
		553
		554	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
331	called on c<$cv>, while servicing other watchers normally.	555	>> methods have been called on c<$cv>, while servicing other watchers
		556	normally.
332		557
333	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
334	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.
335		566
336	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
337	(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
338	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
339	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
340	condition variables with some kind of request results and supporting	571	condition variables with some kind of request results and supporting
341	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,
342	while still suppporting blocking waits if the caller so desires).	573	while still supporting blocking waits if the caller so desires).
343		574
344	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
345	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
346	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	577	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
347	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	578	can supply.
348	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
349	from different coroutines, however).
350		579
351	=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).
352		585
353	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
354	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
355	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.
356		605
357	=back	606	=back
358
359	Example:
360
361	# wait till the result is ready
362	my $result_ready = AnyEvent->condvar;
363
364	# do something such as adding a timer
365	# or socket watcher the calls $result_ready->broadcast
366	# when the "result" is ready.
367	# in this case, we simply use a timer:
368	my $w = AnyEvent->timer (
369	after => 1,
370	cb => sub { $result_ready->broadcast },
371	);
372
373	# this "blocks" (while handling events) till the watcher
374	# calls broadcast
375	$result_ready->wait;
376		607
377	=head1 GLOBAL VARIABLES AND FUNCTIONS	608	=head1 GLOBAL VARIABLES AND FUNCTIONS
378		609
379	=over 4	610	=over 4
380		611
…		…
386	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	617	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
387	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	618	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
388		619
389	The known classes so far are:	620	The known classes so far are:
390		621
391	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
392	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
393	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	622	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
394	AnyEvent::Impl::Event based on Event, second best choice.	623	AnyEvent::Impl::Event based on Event, second best choice.
		624	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
395	AnyEvent::Impl::Glib based on Glib, third-best choice.	625	AnyEvent::Impl::Glib based on Glib, third-best choice.
396	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
397	AnyEvent::Impl::Tk based on Tk, very bad choice.	626	AnyEvent::Impl::Tk based on Tk, very bad choice.
398	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	627	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
399	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	628	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
400	AnyEvent::Impl::POE based on POE, not generic enough for full support.	629	AnyEvent::Impl::POE based on POE, not generic enough for full support.
401		630
…		…
414	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	643	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
415	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
416	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
417	runtime.	646	runtime.
418		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
419	=back	669	=back
420		670
421	=head1 WHAT TO DO IN A MODULE	671	=head1 WHAT TO DO IN A MODULE
422		672
423	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
…		…
426	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
427	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
428	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
429	to load the event module first.	679	to load the event module first.
430		680
431	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
432	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
433	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
434	events is to stay interactive.	684	events is to stay interactive.
435		685
436	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
437	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
438	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 >>
439	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).
440		690
441	=head1 WHAT TO DO IN THE MAIN PROGRAM	691	=head1 WHAT TO DO IN THE MAIN PROGRAM
442		692
443	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
…		…
445		695
446	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
447	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
448	decide which implementation to chose if some module relies on it.	698	decide which implementation to chose if some module relies on it.
449		699
450	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
451	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
452	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
453	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
454	modules might create watchers when they are loaded, and AnyEvent will	704	modules might create watchers when they are loaded, and AnyEvent will
455	decide on the event model to use as soon as it creates watchers, and it	705	decide on the event model to use as soon as it creates watchers, and it
456	might chose the wrong one unless you load the correct one yourself.	706	might chose the wrong one unless you load the correct one yourself.
457		707
458	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
459	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	709	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
460	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
461		728
462	=head1 OTHER MODULES	729	=head1 OTHER MODULES
463		730
464	The following is a non-exhaustive list of additional modules that use	731	The following is a non-exhaustive list of additional modules that use
465	AnyEvent and can therefore be mixed easily with other AnyEvent modules	732	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
477		744
478	Provide read and write buffers and manages watchers for reads and writes.	745	Provide read and write buffers and manages watchers for reads and writes.
479		746
480	=item L<AnyEvent::Socket>	747	=item L<AnyEvent::Socket>
481		748
482	Provides a means to do non-blocking connects, accepts etc.	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.
483		761
484	=item L<AnyEvent::HTTPD>	762	=item L<AnyEvent::HTTPD>
485		763
486	Provides a simple web application server framework.	764	Provides a simple web application server framework.
487
488	=item L<AnyEvent::DNS>
489
490	Provides asynchronous DNS resolver capabilities, beyond what
491	L<AnyEvent::Util> offers.
492		765
493	=item L<AnyEvent::FastPing>	766	=item L<AnyEvent::FastPing>
494		767
495	The fastest ping in the west.	768	The fastest ping in the west.
496		769
…		…
511		784
512	High level API for event-based execution flow control.	785	High level API for event-based execution flow control.
513		786
514	=item L<Coro>	787	=item L<Coro>
515		788
516	Has special support for AnyEvent.	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.
517		801
518	=item L<IO::Lambda>	802	=item L<IO::Lambda>
519		803
520	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	804	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
521
522	=item L<IO::AIO>
523
524	Truly asynchronous I/O, should be in the toolbox of every event
525	programmer. Can be trivially made to use AnyEvent.
526
527	=item L<BDB>
528
529	Truly asynchronous Berkeley DB access. Can be trivially made to use
530	AnyEvent.
531		805
532	=back	806	=back
533		807
534	=cut	808	=cut
535		809
…		…
538	no warnings;	812	no warnings;
539	use strict;	813	use strict;
540		814
541	use Carp;	815	use Carp;
542		816
543	our $VERSION = '3.3';	817	our $VERSION = 4.14;
544	our $MODEL;	818	our $MODEL;
545		819
546	our $AUTOLOAD;	820	our $AUTOLOAD;
547	our @ISA;	821	our @ISA;
548		822
		823	our @REGISTRY;
		824
		825	our $WIN32;
		826
		827	BEGIN {
		828	my $win32 = ! ! ($^O =~ /mswin32/i);
		829	eval "sub WIN32(){ $win32 }";
		830	}
		831
549	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	832	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
550		833
551	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	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		841	}
552		842
553	my @models = (	843	my @models = (
554	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
555	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
556	[EV:: => AnyEvent::Impl::EV::],	844	[EV:: => AnyEvent::Impl::EV::],
557	[Event:: => AnyEvent::Impl::Event::],	845	[Event:: => AnyEvent::Impl::Event::],
558	[Glib:: => AnyEvent::Impl::Glib::],
559	[Tk:: => AnyEvent::Impl::Tk::],
560	[Wx:: => AnyEvent::Impl::POE::],
561	[Prima:: => AnyEvent::Impl::POE::],
562	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	846	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
563	# everything below here will not be autoprobed as the pureperl backend should work everywhere	847	# everything below here will not be autoprobed
		848	# as the pureperl backend should work everywhere
		849	# and is usually faster
		850	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		851	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
564	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	852	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
565	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	853	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
566	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	854	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		855	[Wx:: => AnyEvent::Impl::POE::],
		856	[Prima:: => AnyEvent::Impl::POE::],
567	);	857	);
568		858
569	our %method = map +($_ => 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	}
570		882
571	sub detect() {	883	sub detect() {
572	unless ($MODEL) {	884	unless ($MODEL) {
573	no strict 'refs';	885	no strict 'refs';
		886	local $SIG{__DIE__};
574		887
575	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	888	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
576	my $model = "AnyEvent::Impl::$1";	889	my $model = "AnyEvent::Impl::$1";
577	if (eval "require $model") {	890	if (eval "require $model") {
578	$MODEL = $model;	891	$MODEL = $model;
…		…
608	last;	921	last;
609	}	922	}
610	}	923	}
611		924
612	$MODEL	925	$MODEL
613	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	926	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
614	}	927	}
615	}	928	}
616		929
617	unshift @ISA, $MODEL;	930	unshift @ISA, $MODEL;
618	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	931	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		932
		933	(shift @post_detect)->() while @post_detect;
619	}	934	}
620		935
621	$MODEL	936	$MODEL
622	}	937	}
623		938
…		…
633	$class->$func (@_);	948	$class->$func (@_);
634	}	949	}
635		950
636	package AnyEvent::Base;	951	package AnyEvent::Base;
637		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
638	# default implementation for ->condvar, ->wait, ->broadcast	960	# default implementation for ->condvar
639		961
640	sub condvar {	962	sub condvar {
641	bless \my $flag, "AnyEvent::Base::CondVar"	963	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
642	}
643
644	sub AnyEvent::Base::CondVar::broadcast {
645	${$_[0]}++;
646	}
647
648	sub AnyEvent::Base::CondVar::wait {
649	AnyEvent->one_event while !${$_[0]};
650	}	964	}
651		965
652	# default implementation for ->signal	966	# default implementation for ->signal
653		967
654	our %SIG_CB;	968	our %SIG_CB;
…		…
707	or Carp::croak "required option 'pid' is missing";	1021	or Carp::croak "required option 'pid' is missing";
708		1022
709	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1023	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
710		1024
711	unless ($WNOHANG) {	1025	unless ($WNOHANG) {
712	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1026	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
713	}	1027	}
714		1028
715	unless ($CHLD_W) {	1029	unless ($CHLD_W) {
716	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1030	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
717	# 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
…		…
727	delete $PID_CB{$pid}{$cb};	1041	delete $PID_CB{$pid}{$cb};
728	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1042	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
729		1043
730	undef $CHLD_W unless keys %PID_CB;	1044	undef $CHLD_W unless keys %PID_CB;
731	}	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;
732		1106
733	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1107	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
734		1108
735	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
736	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
…		…
793	model it chooses.	1167	model it chooses.
794		1168
795	=item C<PERL_ANYEVENT_MODEL>	1169	=item C<PERL_ANYEVENT_MODEL>
796		1170
797	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
798	autodetection and -probing kicks in. It must be a string consisting	1172	auto detection and -probing kicks in. It must be a string consisting
799	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1173	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
800	and the resulting module name is loaded and if the load was successful,	1174	and the resulting module name is loaded and if the load was successful,
801	used as event model. If it fails to load AnyEvent will proceed with	1175	used as event model. If it fails to load AnyEvent will proceed with
802	autodetection and -probing.	1176	auto detection and -probing.
803		1177
804	This functionality might change in future versions.	1178	This functionality might change in future versions.
805		1179
806	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
807	could start your program like this:	1181	could start your program like this:
808		1182
809	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.
810		1220
811	=back	1221	=back
812		1222
813	=head1 EXAMPLE PROGRAM	1223	=head1 EXAMPLE PROGRAM
814		1224
…		…
825	poll => 'r',	1235	poll => 'r',
826	cb => sub {	1236	cb => sub {
827	warn "io event <$_[0]>\n"; # will always output <r>	1237	warn "io event <$_[0]>\n"; # will always output <r>
828	chomp (my $input = <STDIN>); # read a line	1238	chomp (my $input = <STDIN>); # read a line
829	warn "read: $input\n"; # output what has been read	1239	warn "read: $input\n"; # output what has been read
830	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1240	$cv->send if $input =~ /^q/i; # quit program if /^q/i
831	},	1241	},
832	);	1242	);
833		1243
834	my $time_watcher; # can only be used once	1244	my $time_watcher; # can only be used once
835		1245
…		…
840	});	1250	});
841	}	1251	}
842		1252
843	new_timer; # create first timer	1253	new_timer; # create first timer
844		1254
845	$cv->wait; # wait until user enters /^q/i	1255	$cv->recv; # wait until user enters /^q/i
846		1256
847	=head1 REAL-WORLD EXAMPLE	1257	=head1 REAL-WORLD EXAMPLE
848		1258
849	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
850	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:
…		…
900	syswrite $txn->{fh}, $txn->{request}	1310	syswrite $txn->{fh}, $txn->{request}
901	or die "connection or write error";	1311	or die "connection or write error";
902	$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 });
903		1313
904	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
905	result and signals any possible waiters that the request ahs finished:	1315	result and signals any possible waiters that the request has finished:
906		1316
907	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1317	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
908		1318
909	if (end-of-file or data complete) {	1319	if (end-of-file or data complete) {
910	$txn->{result} = $txn->{buf};	1320	$txn->{result} = $txn->{buf};
911	$txn->{finished}->broadcast;	1321	$txn->{finished}->send;
912	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1322	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
913	}	1323	}
914		1324
915	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
916	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
917	data:	1327	data:
918		1328
919	$txn->{finished}->wait;	1329	$txn->{finished}->recv;
920	return $txn->{result};	1330	return $txn->{result};
921		1331
922	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)
923	that occured during request processing. The C<result> method detects	1333	that occurred during request processing. The C<result> method detects
924	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)
925	and just throws the exception, which means connection errors and other	1335	and just throws the exception, which means connection errors and other
926	problems get reported tot he code that tries to use the result, not in a	1336	problems get reported tot he code that tries to use the result, not in a
927	random callback.	1337	random callback.
928		1338
…		…
959		1369
960	my $quit = AnyEvent->condvar;	1370	my $quit = AnyEvent->condvar;
961		1371
962	$fcp->txn_client_get ($url)->cb (sub {	1372	$fcp->txn_client_get ($url)->cb (sub {
963	...	1373	...
964	$quit->broadcast;	1374	$quit->send;
965	});	1375	});
966		1376
967	$quit->wait;	1377	$quit->recv;
968		1378
969		1379
970	=head1 BENCHMARKS	1380	=head1 BENCHMARKS
971		1381
972	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
…		…
974	of various event loops I prepared some benchmarks.	1384	of various event loops I prepared some benchmarks.
975		1385
976	=head2 BENCHMARKING ANYEVENT OVERHEAD	1386	=head2 BENCHMARKING ANYEVENT OVERHEAD
977		1387
978	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
979	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
980	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,
981	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.
982		1392
983	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
984	distribution.	1394	distribution.
…		…
1001	all watchers, to avoid adding memory overhead. That means closure creation	1411	all watchers, to avoid adding memory overhead. That means closure creation
1002	and memory usage is not included in the figures.	1412	and memory usage is not included in the figures.
1003		1413
1004	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
1005	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
1006	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1416	invoked "watcher" times, it would C<< ->send >> a condvar once to
1007	signal the end of this phase.	1417	signal the end of this phase.
1008		1418
1009	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
1010	watcher.	1420	watcher.
1011		1421
…		…
1071	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()
1072	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
1073	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
1074	above).	1484	above).
1075		1485
1076	C<POE>, regardless of underlying event loop (whether using its pure	1486	C<POE>, regardless of underlying event loop (whether using its pure perl
1077	perl select-based backend or the Event module, the POE-EV backend	1487	select-based backend or the Event module, the POE-EV backend couldn't
1078	couldn't be tested because it wasn't working) shows abysmal performance	1488	be tested because it wasn't working) shows abysmal performance and
1079	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
1080	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
1081	requirements are caused by requiring a session for each watcher). Watcher	1491	requirements are caused by requiring a session for each watcher). Watcher
1082	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1492	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1493	implementation.
		1494
1083	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
1084	really account for this, as session creation overhead is small compared	1496	for the performance issues, though, as session creation overhead is
1085	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
1086	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).
1087		1502
1088	=head3 Summary	1503	=head3 Summary
1089		1504
1090	=over 4	1505	=over 4
1091		1506
…		…
1102		1517
1103	=back	1518	=back
1104		1519
1105	=head2 BENCHMARKING THE LARGE SERVER CASE	1520	=head2 BENCHMARKING THE LARGE SERVER CASE
1106		1521
1107	This benchmark atcually benchmarks the event loop itself. It works by	1522	This benchmark actually benchmarks the event loop itself. It works by
1108	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
1109	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
1110	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
1111	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".
1112		1527
1113	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
1114	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
1115	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
1116	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
1117	most timeouts work (and puts extra pressure on the event loops).	1532	most timeouts work (and puts extra pressure on the event loops).
1118		1533
1119	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
1120	(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
1121	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.
1122		1537
1123	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
1124	distribution.	1539	distribution.
…		…
1126	=head3 Explanation of the columns	1541	=head3 Explanation of the columns
1127		1542
1128	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
1129	each server has a read and write socket end).	1544	each server has a read and write socket end).
1130		1545
1131	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
1132	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.
1133		1548
1134	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
1135	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
1136	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
…		…
1170		1585
1171	=head3 Summary	1586	=head3 Summary
1172		1587
1173	=over 4	1588	=over 4
1174		1589
1175	=item * The pure perl implementation performs extremely well, considering	1590	=item * The pure perl implementation performs extremely well.
1176	that it uses select.
1177		1591
1178	=item * Avoid Glib or POE in large projects where performance matters.	1592	=item * Avoid Glib or POE in large projects where performance matters.
1179		1593
1180	=back	1594	=back
1181		1595
…		…
1210	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
1211	them).	1625	them).
1212		1626
1213	EV is again fastest.	1627	EV is again fastest.
1214		1628
1215	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
1216	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
1217	code to execute in the inner loop, and perl's function calling overhead is	1631	matter.
1218	high, and updating all the data structures is costly).
1219
1220	The pure perl event loop is much slower, but still competitive.
1221		1632
1222	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
1223	others.	1634	others.
1224		1635
1225	=head3 Summary	1636	=head3 Summary
…		…
1233		1644
1234		1645
1235	=head1 FORK	1646	=head1 FORK
1236		1647
1237	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
1238	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.
1239		1651
1240	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
1241	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.
1242		1654
1243		1655
…		…
1251	specified in the variable.	1663	specified in the variable.
1252		1664
1253	You can make AnyEvent completely ignore this variable by deleting it	1665	You can make AnyEvent completely ignore this variable by deleting it
1254	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:
1255		1667
1256	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1668	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1257		1669
1258	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).
1259		1675
1260		1676
1261	=head1 SEE ALSO	1677	=head1 SEE ALSO
1262		1678
1263	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1679	Utility functions: L<AnyEvent::Util>.
1264	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1680
		1681	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1265	L<Event::Lib>, L<Qt>, L<POE>.	1682	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1266		1683
1267	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1684	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1268	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1685	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1269	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1686	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1270	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1687	L<AnyEvent::Impl::POE>.
1271		1688
		1689	Non-blocking file handles, sockets, TCP clients and
		1690	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1691
		1692	Asynchronous DNS: L<AnyEvent::DNS>.
		1693
		1694	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1695
1272	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1696	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1273		1697
1274		1698
1275	=head1 AUTHOR	1699	=head1 AUTHOR
1276		1700
1277	Marc Lehmann <schmorp@schmorp.de>	1701	Marc Lehmann <schmorp@schmorp.de>
1278	http://home.schmorp.de/	1702	http://home.schmorp.de/
1279		1703
1280	=cut	1704	=cut
1281		1705
1282	1	1706	1
1283		1707

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.101 by root, Sun Apr 27 19:36:55 2008 UTC vs. Revision 1.155 by root, Fri Jun 6 07:07:01 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.101 by root, Sun Apr 27 19:36:55 2008 UTC vs.
Revision 1.155 by root, Fri Jun 6 07:07:01 2008 UTC