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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.105 by root, Thu May 1 12:35:54 2008 UTC vs.
Revision 1.160 by root, Sun Jun 22 12:17:47 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
302	If you are familiar with some event loops you will know that all of them	375	If you are familiar with some event loops you will know that all of them
303	require you to run some blocking "loop", "run" or similar function that	376	require you to run some blocking "loop", "run" or similar function that
…		…
312	Condition variables can be created by calling the C<< AnyEvent->condvar	385	Condition variables can be created by calling the C<< AnyEvent->condvar
313	>> method, usually without arguments. The only argument pair allowed is	386	>> method, usually without arguments. The only argument pair allowed is
314	C<cb>, which specifies a callback to be called when the condition variable	387	C<cb>, which specifies a callback to be called when the condition variable
315	becomes true.	388	becomes true.
316		389
317	After creation, the conditon variable is "false" until it becomes "true"	390	After creation, the condition variable is "false" until it becomes "true"
318	by calling the C<broadcast> method.	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).
319		394
320	Condition variables are similar to callbacks, except that you can	395	Condition variables are similar to callbacks, except that you can
321	optionally wait for them. They can also be called merge points - points	396	optionally wait for them. They can also be called merge points - points
322	in time where multiple outstandign events have been processed. And yet	397	in time where multiple outstanding events have been processed. And yet
323	another way to call them is transations - each condition variable can be	398	another way to call them is transactions - each condition variable can be
324	used to represent a transaction, which finishes at some point and delivers	399	used to represent a transaction, which finishes at some point and delivers
325	a result.	400	a result.
326		401
327	Condition variables are very useful to signal that something has finished,	402	Condition variables are very useful to signal that something has finished,
328	for example, if you write a module that does asynchronous http requests,	403	for example, if you write a module that does asynchronous http requests,
329	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
330	availability of results. The user can either act when the callback is	405	availability of results. The user can either act when the callback is
331	called or can synchronously C<< ->wait >> for the results.	406	called or can synchronously C<< ->recv >> for the results.
332		407
333	You can also use them to simulate traditional event loops - for example,	408	You can also use them to simulate traditional event loops - for example,
334	you can block your main program until an event occurs - for example, you	409	you can block your main program until an event occurs - for example, you
335	could C<< ->wait >> in your main program until the user clicks the Quit	410	could C<< ->recv >> in your main program until the user clicks the Quit
336	button of your app, which would C<< ->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 pieces 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	Condition variables are represented by hash refs in perl, and the keys	419	Condition variables are represented by hash refs in perl, and the keys
…		…
346	easy (it is often useful to build your own transaction class on top of	421	easy (it is often useful to build your own transaction class on top of
347	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call	422	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
348	it's C<new> method in your own C<new> method.	423	it's C<new> method in your own C<new> method.
349		424
350	There are two "sides" to a condition variable - the "producer side" which	425	There are two "sides" to a condition variable - the "producer side" which
351	eventually calls C<< -> broadcast >>, and the "consumer side", which waits	426	eventually calls C<< -> send >>, and the "consumer side", which waits
352	for the broadcast to occur.	427	for the send to occur.
353		428
354	Example:	429	Example: wait for a timer.
355		430
356	# wait till the result is ready	431	# wait till the result is ready
357	my $result_ready = AnyEvent->condvar;	432	my $result_ready = AnyEvent->condvar;
358		433
359	# do something such as adding a timer	434	# do something such as adding a timer
360	# or socket watcher the calls $result_ready->broadcast	435	# or socket watcher the calls $result_ready->send
361	# when the "result" is ready.	436	# when the "result" is ready.
362	# in this case, we simply use a timer:	437	# in this case, we simply use a timer:
363	my $w = AnyEvent->timer (	438	my $w = AnyEvent->timer (
364	after => 1,	439	after => 1,
365	cb => sub { $result_ready->broadcast },	440	cb => sub { $result_ready->send },
366	);	441	);
367		442
368	# this "blocks" (while handling events) till the callback	443	# this "blocks" (while handling events) till the callback
369	# calls broadcast	444	# calls send
370	$result_ready->wait;	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;
371		453
372	=head3 METHODS FOR PRODUCERS	454	=head3 METHODS FOR PRODUCERS
373		455
374	These methods should only be used by the producing side, i.e. the	456	These methods should only be used by the producing side, i.e. the
375	code/module that eventually broadcasts the signal. Note that it is also	457	code/module that eventually sends the signal. Note that it is also
376	the producer side which creates the condvar in most cases, but it isn't	458	the producer side which creates the condvar in most cases, but it isn't
377	uncommon for the consumer to create it as well.	459	uncommon for the consumer to create it as well.
378		460
379	=over 4	461	=over 4
380		462
381	=item $cv->broadcast (...)	463	=item $cv->send (...)
382		464
383	Flag the condition as ready - a running C<< ->wait >> and all further	465	Flag the condition as ready - a running C<< ->recv >> and all further
384	calls to C<wait> will (eventually) return after this method has been	466	calls to C<recv> will (eventually) return after this method has been
385	called. If nobody is waiting the broadcast will be remembered.	467	called. If nobody is waiting the send will be remembered.
386		468
387	If a callback has been set on the condition variable, it is called	469	If a callback has been set on the condition variable, it is called
388	immediately from within broadcast.	470	immediately from within send.
389		471
390	Any arguments passed to the C<broadcast> call will be returned by all	472	Any arguments passed to the C<send> call will be returned by all
391	future C<< ->wait >> calls.	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).
392		483
393	=item $cv->croak ($error)	484	=item $cv->croak ($error)
394		485
395	Similar to broadcast, but causes all call's wait C<< ->wait >> to invoke	486	Similar to send, but causes all call's to C<< ->recv >> to invoke
396	C<Carp::croak> with the given error message/object/scalar.	487	C<Carp::croak> with the given error message/object/scalar.
397		488
398	This can be used to signal any errors to the condition variable	489	This can be used to signal any errors to the condition variable
399	user/consumer.	490	user/consumer.
400		491
401	=item $cv->begin ([group callback])	492	=item $cv->begin ([group callback])
402		493
403	=item $cv->end	494	=item $cv->end
		495
		496	These two methods are EXPERIMENTAL and MIGHT CHANGE.
404		497
405	These two methods can be used to combine many transactions/events into	498	These two methods can be used to combine many transactions/events into
406	one. For example, a function that pings many hosts in parallel might want	499	one. For example, a function that pings many hosts in parallel might want
407	to use a condition variable for the whole process.	500	to use a condition variable for the whole process.
408		501
409	Every call to C<< ->begin >> will increment a counter, and every call to	502	Every call to C<< ->begin >> will increment a counter, and every call to
410	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	503	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
411	>>, the (last) callback passed to C<begin> will be executed. That callback	504	>>, the (last) callback passed to C<begin> will be executed. That callback
412	is I<supposed> to call C<< ->broadcast >>, but that is not required. If no	505	is I<supposed> to call C<< ->send >>, but that is not required. If no
413	callback was set, C<broadcast> will be called without any arguments.	506	callback was set, C<send> will be called without any arguments.
414		507
415	Let's clarify this with the ping example:	508	Let's clarify this with the ping example:
416		509
417	my $cv = AnyEvent->condvar;	510	my $cv = AnyEvent->condvar;
418		511
419	my %result;	512	my %result;
420	$cv->begin (sub { $cv->broadcast (\%result) });	513	$cv->begin (sub { $cv->send (\%result) });
421		514
422	for my $host (@list_of_hosts) {	515	for my $host (@list_of_hosts) {
423	$cv->begin;	516	$cv->begin;
424	ping_host_then_call_callback $host, sub {	517	ping_host_then_call_callback $host, sub {
425	$result{$host} = ...;	518	$result{$host} = ...;
…		…
428	}	521	}
429		522
430	$cv->end;	523	$cv->end;
431		524
432	This code fragment supposedly pings a number of hosts and calls	525	This code fragment supposedly pings a number of hosts and calls
433	C<broadcast> after results for all then have have been gathered - in any	526	C<send> after results for all then have have been gathered - in any
434	order. To achieve this, the code issues a call to C<begin> when it starts	527	order. To achieve this, the code issues a call to C<begin> when it starts
435	each ping request and calls C<end> when it has received some result for	528	each ping request and calls C<end> when it has received some result for
436	it. Since C<begin> and C<end> only maintain a counter, the order in which	529	it. Since C<begin> and C<end> only maintain a counter, the order in which
437	results arrive is not relevant.	530	results arrive is not relevant.
438		531
439	There is an additional bracketing call to C<begin> and C<end> outside the	532	There is an additional bracketing call to C<begin> and C<end> outside the
440	loop, which serves two important purposes: first, it sets the callback	533	loop, which serves two important purposes: first, it sets the callback
441	to be called once the counter reaches C<0>, and second, it ensures that	534	to be called once the counter reaches C<0>, and second, it ensures that
442	broadcast is called even when C<no> hosts are being pinged (the loop	535	C<send> is called even when C<no> hosts are being pinged (the loop
443	doesn't execute once).	536	doesn't execute once).
444		537
445	This is the general pattern when you "fan out" into multiple subrequests:	538	This is the general pattern when you "fan out" into multiple subrequests:
446	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	539	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
447	is called at least once, and then, for each subrequest you start, call	540	is called at least once, and then, for each subrequest you start, call
448	C<begin> and for eahc subrequest you finish, call C<end>.	541	C<begin> and for each subrequest you finish, call C<end>.
449		542
450	=back	543	=back
451		544
452	=head3 METHODS FOR CONSUMERS	545	=head3 METHODS FOR CONSUMERS
453		546
454	These methods should only be used by the consuming side, i.e. the	547	These methods should only be used by the consuming side, i.e. the
455	code awaits the condition.	548	code awaits the condition.
456		549
457	=item $cv->wait	550	=over 4
458		551
		552	=item $cv->recv
		553
459	Wait (blocking if necessary) until the C<< ->broadcast >> or C<< ->croak	554	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
460	>> methods have been called on c<$cv>, while servicing other watchers	555	>> methods have been called on c<$cv>, while servicing other watchers
461	normally.	556	normally.
462		557
463	You can only wait once on a condition - additional calls are valid but	558	You can only wait once on a condition - additional calls are valid but
464	will return immediately.	559	will return immediately.
465		560
466	If an error condition has been set by calling C<< ->croak >>, then this	561	If an error condition has been set by calling C<< ->croak >>, then this
467	function will call C<croak>.	562	function will call C<croak>.
468		563
469	In list context, all parameters passed to C<broadcast> will be returned,	564	In list context, all parameters passed to C<send> will be returned,
470	in scalar context only the first one will be returned.	565	in scalar context only the first one will be returned.
471		566
472	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
473	(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
474	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
475	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
476	condition variables with some kind of request results and supporting	571	condition variables with some kind of request results and supporting
477	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,
478	while still suppporting blocking waits if the caller so desires).	573	while still supporting blocking waits if the caller so desires).
479		574
480	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
481	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
482	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	577	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
483	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	578	can supply.
484	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
485	from different coroutines, however).
486		579
		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).
		585
487	You can ensure that C<< -wait >> never blocks by setting a callback and	586	You can ensure that C<< -recv >> never blocks by setting a callback and
488	only calling C<< ->wait >> from within that callback (or at a later	587	only calling C<< ->recv >> from within that callback (or at a later
489	time). This will work even when the event loop does not support blocking	588	time). This will work even when the event loop does not support blocking
490	waits otherwise.	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 = $cv->cb ([new callback])
		597
		598	This is a mutator function that returns the callback set and optionally
		599	replaces it before doing so.
		600
		601	The callback will be called when the condition becomes "true", i.e. when
		602	C<send> or C<croak> are called, with the only argument being the condition
		603	variable itself. Calling C<recv> inside the callback or at any later time
		604	is guaranteed not to block.
491		605
492	=back	606	=back
493		607
494	=head1 GLOBAL VARIABLES AND FUNCTIONS	608	=head1 GLOBAL VARIABLES AND FUNCTIONS
495		609
…		…
503	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	617	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
504	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	618	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
505		619
506	The known classes so far are:	620	The known classes so far are:
507		621
508	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
509	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
510	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	622	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
511	AnyEvent::Impl::Event based on Event, second best choice.	623	AnyEvent::Impl::Event based on Event, second best choice.
512	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.	624	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
513	AnyEvent::Impl::Glib based on Glib, third-best choice.	625	AnyEvent::Impl::Glib based on Glib, third-best choice.
514	AnyEvent::Impl::Tk based on Tk, very bad choice.	626	AnyEvent::Impl::Tk based on Tk, very bad choice.
…		…
531	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	643	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
532	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
533	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
534	runtime.	646	runtime.
535		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
536	=back	669	=back
537		670
538	=head1 WHAT TO DO IN A MODULE	671	=head1 WHAT TO DO IN A MODULE
539		672
540	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
…		…
543	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
544	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
545	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
546	to load the event module first.	679	to load the event module first.
547		680
548	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
549	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
550	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
551	events is to stay interactive.	684	events is to stay interactive.
552		685
553	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
554	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
555	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 >>
556	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).
557		690
558	=head1 WHAT TO DO IN THE MAIN PROGRAM	691	=head1 WHAT TO DO IN THE MAIN PROGRAM
559		692
560	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
…		…
562		695
563	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
564	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
565	decide which implementation to chose if some module relies on it.	698	decide which implementation to chose if some module relies on it.
566		699
567	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
568	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
569	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
570	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
571	modules might create watchers when they are loaded, and AnyEvent will	704	modules might create watchers when they are loaded, and AnyEvent will
572	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
573	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.
574		707
575	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
576	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	709	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
577	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
578		728
579	=head1 OTHER MODULES	729	=head1 OTHER MODULES
580		730
581	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
582	AnyEvent and can therefore be mixed easily with other AnyEvent modules	732	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
594		744
595	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.
596		746
597	=item L<AnyEvent::Socket>	747	=item L<AnyEvent::Socket>
598		748
599	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.
600		761
601	=item L<AnyEvent::HTTPD>	762	=item L<AnyEvent::HTTPD>
602		763
603	Provides a simple web application server framework.	764	Provides a simple web application server framework.
604		765
605	=item L<AnyEvent::DNS>
606
607	Provides asynchronous DNS resolver capabilities, beyond what
608	L<AnyEvent::Util> offers.
609
610	=item L<AnyEvent::FastPing>	766	=item L<AnyEvent::FastPing>
611		767
612	The fastest ping in the west.	768	The fastest ping in the west.
		769
		770	=item L<AnyEvent::DBI>
		771
		772	Executes DBI requests asynchronously in a proxy process.
613		773
614	=item L<Net::IRC3>	774	=item L<Net::IRC3>
615		775
616	AnyEvent based IRC client module family.	776	AnyEvent based IRC client module family.
617		777
…		…
628		788
629	High level API for event-based execution flow control.	789	High level API for event-based execution flow control.
630		790
631	=item L<Coro>	791	=item L<Coro>
632		792
633	Has special support for AnyEvent.	793	Has special support for AnyEvent via L<Coro::AnyEvent>.
		794
		795	=item L<AnyEvent::AIO>, L<IO::AIO>
		796
		797	Truly asynchronous I/O, should be in the toolbox of every event
		798	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
		799	together.
		800
		801	=item L<AnyEvent::BDB>, L<BDB>
		802
		803	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
		804	IO::AIO and AnyEvent together.
634		805
635	=item L<IO::Lambda>	806	=item L<IO::Lambda>
636		807
637	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	808	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
638
639	=item L<IO::AIO>
640
641	Truly asynchronous I/O, should be in the toolbox of every event
642	programmer. Can be trivially made to use AnyEvent.
643
644	=item L<BDB>
645
646	Truly asynchronous Berkeley DB access. Can be trivially made to use
647	AnyEvent.
648		809
649	=back	810	=back
650		811
651	=cut	812	=cut
652		813
…		…
655	no warnings;	816	no warnings;
656	use strict;	817	use strict;
657		818
658	use Carp;	819	use Carp;
659		820
660	our $VERSION = '3.3';	821	our $VERSION = 4.152;
661	our $MODEL;	822	our $MODEL;
662		823
663	our $AUTOLOAD;	824	our $AUTOLOAD;
664	our @ISA;	825	our @ISA;
665		826
		827	our @REGISTRY;
		828
		829	our $WIN32;
		830
		831	BEGIN {
		832	my $win32 = ! ! ($^O =~ /mswin32/i);
		833	eval "sub WIN32(){ $win32 }";
		834	}
		835
666	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	836	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
667		837
668	our @REGISTRY;	838	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
		839
		840	{
		841	my $idx;
		842	$PROTOCOL{$_} = ++$idx
		843	for reverse split /\s,\s/,
		844	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		845	}
669		846
670	my @models = (	847	my @models = (
671	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
672	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
673	[EV:: => AnyEvent::Impl::EV::],	848	[EV:: => AnyEvent::Impl::EV::],
674	[Event:: => AnyEvent::Impl::Event::],	849	[Event:: => AnyEvent::Impl::Event::],
675	[Tk:: => AnyEvent::Impl::Tk::],
676	[Wx:: => AnyEvent::Impl::POE::],
677	[Prima:: => AnyEvent::Impl::POE::],
678	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	850	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
679	# everything below here will not be autoprobed as the pureperl backend should work everywhere	851	# everything below here will not be autoprobed
680	[Glib:: => AnyEvent::Impl::Glib::],	852	# as the pureperl backend should work everywhere
		853	# and is usually faster
		854	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		855	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
681	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	856	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
682	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	857	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
683	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	858	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		859	[Wx:: => AnyEvent::Impl::POE::],
		860	[Prima:: => AnyEvent::Impl::POE::],
684	);	861	);
685		862
686	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	863	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);
		864
		865	our @post_detect;
		866
		867	sub post_detect(&) {
		868	my ($cb) = @_;
		869
		870	if ($MODEL) {
		871	$cb->();
		872
		873	1
		874	} else {
		875	push @post_detect, $cb;
		876
		877	defined wantarray
		878	? bless \$cb, "AnyEvent::Util::PostDetect"
		879	: ()
		880	}
		881	}
		882
		883	sub AnyEvent::Util::PostDetect::DESTROY {
		884	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		885	}
687		886
688	sub detect() {	887	sub detect() {
689	unless ($MODEL) {	888	unless ($MODEL) {
690	no strict 'refs';	889	no strict 'refs';
		890	local $SIG{__DIE__};
691		891
692	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	892	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
693	my $model = "AnyEvent::Impl::$1";	893	my $model = "AnyEvent::Impl::$1";
694	if (eval "require $model") {	894	if (eval "require $model") {
695	$MODEL = $model;	895	$MODEL = $model;
…		…
725	last;	925	last;
726	}	926	}
727	}	927	}
728		928
729	$MODEL	929	$MODEL
730	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.";	930	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
731	}	931	}
732	}	932	}
733		933
734	unshift @ISA, $MODEL;	934	unshift @ISA, $MODEL;
735	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	935	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		936
		937	(shift @post_detect)->() while @post_detect;
736	}	938	}
737		939
738	$MODEL	940	$MODEL
739	}	941	}
740		942
…		…
750	$class->$func (@_);	952	$class->$func (@_);
751	}	953	}
752		954
753	package AnyEvent::Base;	955	package AnyEvent::Base;
754		956
		957	# default implementation for now and time
		958
		959	use Time::HiRes ();
		960
		961	sub time { Time::HiRes::time }
		962	sub now { Time::HiRes::time }
		963
755	# default implementation for ->condvar, ->wait, ->broadcast	964	# default implementation for ->condvar
756		965
757	sub condvar {	966	sub condvar {
758	bless \my $flag, "AnyEvent::Base::CondVar"	967	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
759	}
760
761	sub AnyEvent::Base::CondVar::broadcast {
762	${$_[0]}++;
763	}
764
765	sub AnyEvent::Base::CondVar::wait {
766	AnyEvent->one_event while !${$_[0]};
767	}	968	}
768		969
769	# default implementation for ->signal	970	# default implementation for ->signal
770		971
771	our %SIG_CB;	972	our %SIG_CB;
…		…
824	or Carp::croak "required option 'pid' is missing";	1025	or Carp::croak "required option 'pid' is missing";
825		1026
826	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1027	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
827		1028
828	unless ($WNOHANG) {	1029	unless ($WNOHANG) {
829	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	1030	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
830	}	1031	}
831		1032
832	unless ($CHLD_W) {	1033	unless ($CHLD_W) {
833	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1034	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
834	# child could be a zombie already, so make at least one round	1035	# child could be a zombie already, so make at least one round
…		…
844	delete $PID_CB{$pid}{$cb};	1045	delete $PID_CB{$pid}{$cb};
845	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1046	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
846		1047
847	undef $CHLD_W unless keys %PID_CB;	1048	undef $CHLD_W unless keys %PID_CB;
848	}	1049	}
		1050
		1051	package AnyEvent::CondVar;
		1052
		1053	our @ISA = AnyEvent::CondVar::Base::;
		1054
		1055	package AnyEvent::CondVar::Base;
		1056
		1057	use overload
		1058	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1059	fallback => 1;
		1060
		1061	sub _send {
		1062	# nop
		1063	}
		1064
		1065	sub send {
		1066	my $cv = shift;
		1067	$cv->{_ae_sent} = [@_];
		1068	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1069	$cv->_send;
		1070	}
		1071
		1072	sub croak {
		1073	$_[0]{_ae_croak} = $_[1];
		1074	$_[0]->send;
		1075	}
		1076
		1077	sub ready {
		1078	$_[0]{_ae_sent}
		1079	}
		1080
		1081	sub _wait {
		1082	AnyEvent->one_event while !$_[0]{_ae_sent};
		1083	}
		1084
		1085	sub recv {
		1086	$_[0]->_wait;
		1087
		1088	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1089	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1090	}
		1091
		1092	sub cb {
		1093	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1094	$_[0]{_ae_cb}
		1095	}
		1096
		1097	sub begin {
		1098	++$_[0]{_ae_counter};
		1099	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1100	}
		1101
		1102	sub end {
		1103	return if --$_[0]{_ae_counter};
		1104	&{ $_[0]{_ae_end_cb} \|\| sub { $_[0]->send } };
		1105	}
		1106
		1107	# undocumented/compatibility with pre-3.4
		1108	*broadcast = \&send;
		1109	*wait = \&_wait;
849		1110
850	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1111	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
851		1112
852	This is an advanced topic that you do not normally need to use AnyEvent in	1113	This is an advanced topic that you do not normally need to use AnyEvent in
853	a module. This section is only of use to event loop authors who want to	1114	a module. This section is only of use to event loop authors who want to
…		…
910	model it chooses.	1171	model it chooses.
911		1172
912	=item C<PERL_ANYEVENT_MODEL>	1173	=item C<PERL_ANYEVENT_MODEL>
913		1174
914	This can be used to specify the event model to be used by AnyEvent, before	1175	This can be used to specify the event model to be used by AnyEvent, before
915	autodetection and -probing kicks in. It must be a string consisting	1176	auto detection and -probing kicks in. It must be a string consisting
916	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1177	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
917	and the resulting module name is loaded and if the load was successful,	1178	and the resulting module name is loaded and if the load was successful,
918	used as event model. If it fails to load AnyEvent will proceed with	1179	used as event model. If it fails to load AnyEvent will proceed with
919	autodetection and -probing.	1180	auto detection and -probing.
920		1181
921	This functionality might change in future versions.	1182	This functionality might change in future versions.
922		1183
923	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1184	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
924	could start your program like this:	1185	could start your program like this:
925		1186
926	PERL_ANYEVENT_MODEL=Perl perl ...	1187	PERL_ANYEVENT_MODEL=Perl perl ...
		1188
		1189	=item C<PERL_ANYEVENT_PROTOCOLS>
		1190
		1191	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1192	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1193	of auto probing).
		1194
		1195	Must be set to a comma-separated list of protocols or address families,
		1196	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1197	used, and preference will be given to protocols mentioned earlier in the
		1198	list.
		1199
		1200	This variable can effectively be used for denial-of-service attacks
		1201	against local programs (e.g. when setuid), although the impact is likely
		1202	small, as the program has to handle connection errors already-
		1203
		1204	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1205	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1206	- only support IPv4, never try to resolve or contact IPv6
		1207	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1208	IPv6, but prefer IPv6 over IPv4.
		1209
		1210	=item C<PERL_ANYEVENT_EDNS0>
		1211
		1212	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1213	for DNS. This extension is generally useful to reduce DNS traffic, but
		1214	some (broken) firewalls drop such DNS packets, which is why it is off by
		1215	default.
		1216
		1217	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1218	EDNS0 in its DNS requests.
		1219
		1220	=item C<PERL_ANYEVENT_MAX_FORKS>
		1221
		1222	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1223	will create in parallel.
927		1224
928	=back	1225	=back
929		1226
930	=head1 EXAMPLE PROGRAM	1227	=head1 EXAMPLE PROGRAM
931		1228
…		…
942	poll => 'r',	1239	poll => 'r',
943	cb => sub {	1240	cb => sub {
944	warn "io event <$_[0]>\n"; # will always output <r>	1241	warn "io event <$_[0]>\n"; # will always output <r>
945	chomp (my $input = <STDIN>); # read a line	1242	chomp (my $input = <STDIN>); # read a line
946	warn "read: $input\n"; # output what has been read	1243	warn "read: $input\n"; # output what has been read
947	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1244	$cv->send if $input =~ /^q/i; # quit program if /^q/i
948	},	1245	},
949	);	1246	);
950		1247
951	my $time_watcher; # can only be used once	1248	my $time_watcher; # can only be used once
952		1249
…		…
957	});	1254	});
958	}	1255	}
959		1256
960	new_timer; # create first timer	1257	new_timer; # create first timer
961		1258
962	$cv->wait; # wait until user enters /^q/i	1259	$cv->recv; # wait until user enters /^q/i
963		1260
964	=head1 REAL-WORLD EXAMPLE	1261	=head1 REAL-WORLD EXAMPLE
965		1262
966	Consider the L<Net::FCP> module. It features (among others) the following	1263	Consider the L<Net::FCP> module. It features (among others) the following
967	API calls, which are to freenet what HTTP GET requests are to http:	1264	API calls, which are to freenet what HTTP GET requests are to http:
…		…
1017	syswrite $txn->{fh}, $txn->{request}	1314	syswrite $txn->{fh}, $txn->{request}
1018	or die "connection or write error";	1315	or die "connection or write error";
1019	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1316	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
1020		1317
1021	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1318	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
1022	result and signals any possible waiters that the request ahs finished:	1319	result and signals any possible waiters that the request has finished:
1023		1320
1024	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1321	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
1025		1322
1026	if (end-of-file or data complete) {	1323	if (end-of-file or data complete) {
1027	$txn->{result} = $txn->{buf};	1324	$txn->{result} = $txn->{buf};
1028	$txn->{finished}->broadcast;	1325	$txn->{finished}->send;
1029	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1326	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
1030	}	1327	}
1031		1328
1032	The C<result> method, finally, just waits for the finished signal (if the	1329	The C<result> method, finally, just waits for the finished signal (if the
1033	request was already finished, it doesn't wait, of course, and returns the	1330	request was already finished, it doesn't wait, of course, and returns the
1034	data:	1331	data:
1035		1332
1036	$txn->{finished}->wait;	1333	$txn->{finished}->recv;
1037	return $txn->{result};	1334	return $txn->{result};
1038		1335
1039	The actual code goes further and collects all errors (C<die>s, exceptions)	1336	The actual code goes further and collects all errors (C<die>s, exceptions)
1040	that occured during request processing. The C<result> method detects	1337	that occurred during request processing. The C<result> method detects
1041	whether an exception as thrown (it is stored inside the $txn object)	1338	whether an exception as thrown (it is stored inside the $txn object)
1042	and just throws the exception, which means connection errors and other	1339	and just throws the exception, which means connection errors and other
1043	problems get reported tot he code that tries to use the result, not in a	1340	problems get reported tot he code that tries to use the result, not in a
1044	random callback.	1341	random callback.
1045		1342
…		…
1076		1373
1077	my $quit = AnyEvent->condvar;	1374	my $quit = AnyEvent->condvar;
1078		1375
1079	$fcp->txn_client_get ($url)->cb (sub {	1376	$fcp->txn_client_get ($url)->cb (sub {
1080	...	1377	...
1081	$quit->broadcast;	1378	$quit->send;
1082	});	1379	});
1083		1380
1084	$quit->wait;	1381	$quit->recv;
1085		1382
1086		1383
1087	=head1 BENCHMARKS	1384	=head1 BENCHMARKS
1088		1385
1089	To give you an idea of the performance and overheads that AnyEvent adds	1386	To give you an idea of the performance and overheads that AnyEvent adds
…		…
1091	of various event loops I prepared some benchmarks.	1388	of various event loops I prepared some benchmarks.
1092		1389
1093	=head2 BENCHMARKING ANYEVENT OVERHEAD	1390	=head2 BENCHMARKING ANYEVENT OVERHEAD
1094		1391
1095	Here is a benchmark of various supported event models used natively and	1392	Here is a benchmark of various supported event models used natively and
1096	through anyevent. The benchmark creates a lot of timers (with a zero	1393	through AnyEvent. The benchmark creates a lot of timers (with a zero
1097	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1394	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1098	which it is), lets them fire exactly once and destroys them again.	1395	which it is), lets them fire exactly once and destroys them again.
1099		1396
1100	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1397	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1101	distribution.	1398	distribution.
…		…
1118	all watchers, to avoid adding memory overhead. That means closure creation	1415	all watchers, to avoid adding memory overhead. That means closure creation
1119	and memory usage is not included in the figures.	1416	and memory usage is not included in the figures.
1120		1417
1121	I<invoke> is the time, in microseconds, used to invoke a simple	1418	I<invoke> is the time, in microseconds, used to invoke a simple
1122	callback. The callback simply counts down a Perl variable and after it was	1419	callback. The callback simply counts down a Perl variable and after it was
1123	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1420	invoked "watcher" times, it would C<< ->send >> a condvar once to
1124	signal the end of this phase.	1421	signal the end of this phase.
1125		1422
1126	I<destroy> is the time, in microseconds, that it takes to destroy a single	1423	I<destroy> is the time, in microseconds, that it takes to destroy a single
1127	watcher.	1424	watcher.
1128		1425
…		…
1224		1521
1225	=back	1522	=back
1226		1523
1227	=head2 BENCHMARKING THE LARGE SERVER CASE	1524	=head2 BENCHMARKING THE LARGE SERVER CASE
1228		1525
1229	This benchmark atcually benchmarks the event loop itself. It works by	1526	This benchmark actually benchmarks the event loop itself. It works by
1230	creating a number of "servers": each server consists of a socketpair, a	1527	creating a number of "servers": each server consists of a socket pair, a
1231	timeout watcher that gets reset on activity (but never fires), and an I/O	1528	timeout watcher that gets reset on activity (but never fires), and an I/O
1232	watcher waiting for input on one side of the socket. Each time the socket	1529	watcher waiting for input on one side of the socket. Each time the socket
1233	watcher reads a byte it will write that byte to a random other "server".	1530	watcher reads a byte it will write that byte to a random other "server".
1234		1531
1235	The effect is that there will be a lot of I/O watchers, only part of which	1532	The effect is that there will be a lot of I/O watchers, only part of which
1236	are active at any one point (so there is a constant number of active	1533	are active at any one point (so there is a constant number of active
1237	fds for each loop iterstaion, but which fds these are is random). The	1534	fds for each loop iteration, but which fds these are is random). The
1238	timeout is reset each time something is read because that reflects how	1535	timeout is reset each time something is read because that reflects how
1239	most timeouts work (and puts extra pressure on the event loops).	1536	most timeouts work (and puts extra pressure on the event loops).
1240		1537
1241	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1538	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1242	(1%) are active. This mirrors the activity of large servers with many	1539	(1%) are active. This mirrors the activity of large servers with many
1243	connections, most of which are idle at any one point in time.	1540	connections, most of which are idle at any one point in time.
1244		1541
1245	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1542	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1246	distribution.	1543	distribution.
…		…
1248	=head3 Explanation of the columns	1545	=head3 Explanation of the columns
1249		1546
1250	I<sockets> is the number of sockets, and twice the number of "servers" (as	1547	I<sockets> is the number of sockets, and twice the number of "servers" (as
1251	each server has a read and write socket end).	1548	each server has a read and write socket end).
1252		1549
1253	I<create> is the time it takes to create a socketpair (which is	1550	I<create> is the time it takes to create a socket pair (which is
1254	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1551	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1255		1552
1256	I<request>, the most important value, is the time it takes to handle a	1553	I<request>, the most important value, is the time it takes to handle a
1257	single "request", that is, reading the token from the pipe and forwarding	1554	single "request", that is, reading the token from the pipe and forwarding
1258	it to another server. This includes deleting the old timeout and creating	1555	it to another server. This includes deleting the old timeout and creating
…		…
1331	speed most when you have lots of watchers, not when you only have a few of	1628	speed most when you have lots of watchers, not when you only have a few of
1332	them).	1629	them).
1333		1630
1334	EV is again fastest.	1631	EV is again fastest.
1335		1632
1336	Perl again comes second. It is noticably faster than the C-based event	1633	Perl again comes second. It is noticeably faster than the C-based event
1337	loops Event and Glib, although the difference is too small to really	1634	loops Event and Glib, although the difference is too small to really
1338	matter.	1635	matter.
1339		1636
1340	POE also performs much better in this case, but is is still far behind the	1637	POE also performs much better in this case, but is is still far behind the
1341	others.	1638	others.
…		…
1370	specified in the variable.	1667	specified in the variable.
1371		1668
1372	You can make AnyEvent completely ignore this variable by deleting it	1669	You can make AnyEvent completely ignore this variable by deleting it
1373	before the first watcher gets created, e.g. with a C<BEGIN> block:	1670	before the first watcher gets created, e.g. with a C<BEGIN> block:
1374		1671
1375	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1672	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1376		1673
1377	use AnyEvent;	1674	use AnyEvent;
		1675
		1676	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1677	be used to probe what backend is used and gain other information (which is
		1678	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
		1679
		1680
		1681	=head1 BUGS
		1682
		1683	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		1684	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		1685	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		1686	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as
		1687	pronounced).
1378		1688
1379		1689
1380	=head1 SEE ALSO	1690	=head1 SEE ALSO
1381		1691
1382	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1692	Utility functions: L<AnyEvent::Util>.
1383	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1693
		1694	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1384	L<Event::Lib>, L<Qt>, L<POE>.	1695	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1385		1696
1386	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1697	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1387	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1698	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1388	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1699	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1389	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1700	L<AnyEvent::Impl::POE>.
1390		1701
		1702	Non-blocking file handles, sockets, TCP clients and
		1703	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1704
		1705	Asynchronous DNS: L<AnyEvent::DNS>.
		1706
		1707	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1708
1391	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1709	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1392		1710
1393		1711
1394	=head1 AUTHOR	1712	=head1 AUTHOR
1395		1713
1396	Marc Lehmann <schmorp@schmorp.de>	1714	Marc Lehmann <schmorp@schmorp.de>
1397	http://home.schmorp.de/	1715	http://home.schmorp.de/
1398		1716
1399	=cut	1717	=cut
1400		1718
1401	1	1719	1
1402		1720

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.105 by root, Thu May 1 12:35:54 2008 UTC vs. Revision 1.160 by root, Sun Jun 22 12:17:47 2008 UTC

Diff Legend

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.105 by root, Thu May 1 12:35:54 2008 UTC vs.
Revision 1.160 by root, Sun Jun 22 12:17:47 2008 UTC