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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.95 by root, Sat Apr 26 11:06:45 2008 UTC vs.
Revision 1.134 by root, Sun May 25 04:44:04 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		22
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		24
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	26	nowadays. So what is different about AnyEvent?
…		…
57	as those use one of the supported event loops. It is trivial to add new	57	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).	58	event loops to AnyEvent, too, so it is future-proof).
59		59
60	In addition to being free of having to use I<the one and only true event	60	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	61	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	62	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	63	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	64	offering the functionality that is necessary, in as thin as a wrapper as
65	technically possible.	65	technically possible.
66		66
67	Of course, if you want lots of policy (this can arguably be somewhat	67	Of course, if you 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	68	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	69	model, you should I<not> use this module.
70
71		70
72	=head1 DESCRIPTION	71	=head1 DESCRIPTION
73		72
74	L<AnyEvent> provides an identical interface to multiple event loops. This	73	L<AnyEvent> provides an identical interface to multiple event loops. This
75	allows module authors to utilise an event loop without forcing module	74	allows module authors to utilise an event loop without forcing module
…		…
79	The interface itself is vaguely similar, but not identical to the L<Event>	78	The interface itself is vaguely similar, but not identical to the L<Event>
80	module.	79	module.
81		80
82	During the first call of any watcher-creation method, the module tries	81	During the first call of any watcher-creation method, the module tries
83	to detect the currently loaded event loop by probing whether one of the	82	to detect the currently loaded event loop by probing whether one of the
84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	83	following modules is already loaded: L<EV>,
85	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	84	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
86	L<POE>. The first one found is used. If none are found, the module tries	85	L<POE>. The first one found is used. If none are found, the module tries
87	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl	86	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
88	adaptor should always succeed) in the order given. The first one that can	87	adaptor should always succeed) in the order given. The first one that can
89	be successfully loaded will be used. If, after this, still none could be	88	be successfully loaded will be used. If, after this, still none could be
…		…
109		108
110	=head1 WATCHERS	109	=head1 WATCHERS
111		110
112	AnyEvent has the central concept of a I<watcher>, which is an object that	111	AnyEvent has the central concept of a I<watcher>, which is an object that
113	stores relevant data for each kind of event you are waiting for, such as	112	stores relevant data for each kind of event you are waiting for, such as
114	the callback to call, the filehandle to watch, etc.	113	the callback to call, the file handle to watch, etc.
115		114
116	These watchers are normal Perl objects with normal Perl lifetime. After	115	These watchers are normal Perl objects with normal Perl lifetime. After
117	creating a watcher it will immediately "watch" for events and invoke the	116	creating a watcher it will immediately "watch" for events and invoke the
118	callback when the event occurs (of course, only when the event model	117	callback when the event occurs (of course, only when the event model
119	is in control).	118	is in control).
…		…
238		237
239	Although the callback might get passed parameters, their value and	238	Although the callback might get passed parameters, their value and
240	presence is undefined and you cannot rely on them. Portable AnyEvent	239	presence is undefined and you cannot rely on them. Portable AnyEvent
241	callbacks cannot use arguments passed to signal watcher callbacks.	240	callbacks cannot use arguments passed to signal watcher callbacks.
242		241
243	Multiple signal occurances can be clumped together into one callback	242	Multiple signal occurrences can be clumped together into one callback
244	invocation, and callback invocation will be synchronous. synchronous means	243	invocation, and callback invocation will be synchronous. Synchronous means
245	that it might take a while until the signal gets handled by the process,	244	that it might take a while until the signal gets handled by the process,
246	but it is guarenteed not to interrupt any other callbacks.	245	but it is guaranteed not to interrupt any other callbacks.
247		246
248	The main advantage of using these watchers is that you can share a signal	247	The main advantage of using these watchers is that you can share a signal
249	between multiple watchers.	248	between multiple watchers.
250		249
251	This watcher might use C<%SIG>, so programs overwriting those signals	250	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
280		279
281	Example: fork a process and wait for it	280	Example: fork a process and wait for it
282		281
283	my $done = AnyEvent->condvar;	282	my $done = AnyEvent->condvar;
284		283
285	AnyEvent::detect; # force event module to be initialised
286
287	my $pid = fork or exit 5;	284	my $pid = fork or exit 5;
288		285
289	my $w = AnyEvent->child (	286	my $w = AnyEvent->child (
290	pid => $pid,	287	pid => $pid,
291	cb => sub {	288	cb => sub {
292	my ($pid, $status) = @_;	289	my ($pid, $status) = @_;
293	warn "pid $pid exited with status $status";	290	warn "pid $pid exited with status $status";
294	$done->broadcast;	291	$done->send;
295	},	292	},
296	);	293	);
297		294
298	# do something else, then wait for process exit	295	# do something else, then wait for process exit
299	$done->wait;	296	$done->recv;
300		297
301	=head2 CONDITION VARIABLES	298	=head2 CONDITION VARIABLES
302		299
		300	If you are familiar with some event loops you will know that all of them
		301	require you to run some blocking "loop", "run" or similar function that
		302	will actively watch for new events and call your callbacks.
		303
		304	AnyEvent is different, it expects somebody else to run the event loop and
		305	will only block when necessary (usually when told by the user).
		306
		307	The instrument to do that is called a "condition variable", so called
		308	because they represent a condition that must become true.
		309
303	Condition variables can be created by calling the C<< AnyEvent->condvar >>	310	Condition variables can be created by calling the C<< AnyEvent->condvar
304	method without any arguments.	311	>> method, usually without arguments. The only argument pair allowed is
		312	C<cb>, which specifies a callback to be called when the condition variable
		313	becomes true.
305		314
306	A condition variable waits for a condition - precisely that the C<<	315	After creation, the condition variable is "false" until it becomes "true"
307	->broadcast >> method has been called.	316	by calling the C<send> method (or calling the condition variable as if it
		317	were a callback).
308		318
309	They are very useful to signal that a condition has been fulfilled, for	319	Condition variables are similar to callbacks, except that you can
		320	optionally wait for them. They can also be called merge points - points
		321	in time where multiple outstanding events have been processed. And yet
		322	another way to call them is transactions - each condition variable can be
		323	used to represent a transaction, which finishes at some point and delivers
		324	a result.
		325
		326	Condition variables are very useful to signal that something has finished,
310	example, if you write a module that does asynchronous http requests,	327	for example, if you write a module that does asynchronous http requests,
311	then a condition variable would be the ideal candidate to signal the	328	then a condition variable would be the ideal candidate to signal the
312	availability of results.	329	availability of results. The user can either act when the callback is
		330	called or can synchronously C<< ->recv >> for the results.
313		331
314	You can also use condition variables to block your main program until	332	You can also use them to simulate traditional event loops - for example,
315	an event occurs - for example, you could C<< ->wait >> in your main	333	you can block your main program until an event occurs - for example, you
316	program until the user clicks the Quit button in your app, which would C<<	334	could C<< ->recv >> in your main program until the user clicks the Quit
317	->broadcast >> the "quit" event.	335	button of your app, which would C<< ->send >> the "quit" event.
318		336
319	Note that condition variables recurse into the event loop - if you have	337	Note that condition variables recurse into the event loop - if you have
320	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	338	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
321	lose. Therefore, condition variables are good to export to your caller, but	339	lose. Therefore, condition variables are good to export to your caller, but
322	you should avoid making a blocking wait yourself, at least in callbacks,	340	you should avoid making a blocking wait yourself, at least in callbacks,
323	as this asks for trouble.	341	as this asks for trouble.
324		342
325	This object has two methods:	343	Condition variables are represented by hash refs in perl, and the keys
		344	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		345	easy (it is often useful to build your own transaction class on top of
		346	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		347	it's C<new> method in your own C<new> method.
		348
		349	There are two "sides" to a condition variable - the "producer side" which
		350	eventually calls C<< -> send >>, and the "consumer side", which waits
		351	for the send to occur.
		352
		353	Example: wait for a timer.
		354
		355	# wait till the result is ready
		356	my $result_ready = AnyEvent->condvar;
		357
		358	# do something such as adding a timer
		359	# or socket watcher the calls $result_ready->send
		360	# when the "result" is ready.
		361	# in this case, we simply use a timer:
		362	my $w = AnyEvent->timer (
		363	after => 1,
		364	cb => sub { $result_ready->send },
		365	);
		366
		367	# this "blocks" (while handling events) till the callback
		368	# calls send
		369	$result_ready->recv;
		370
		371	Example: wait for a timer, but take advantage of the fact that
		372	condition variables are also code references.
		373
		374	my $done = AnyEvent->condvar;
		375	my $delay = AnyEvent->timer (after => 5, cb => $done);
		376	$done->recv;
		377
		378	=head3 METHODS FOR PRODUCERS
		379
		380	These methods should only be used by the producing side, i.e. the
		381	code/module that eventually sends the signal. Note that it is also
		382	the producer side which creates the condvar in most cases, but it isn't
		383	uncommon for the consumer to create it as well.
326		384
327	=over 4	385	=over 4
328		386
		387	=item $cv->send (...)
		388
		389	Flag the condition as ready - a running C<< ->recv >> and all further
		390	calls to C<recv> will (eventually) return after this method has been
		391	called. If nobody is waiting the send will be remembered.
		392
		393	If a callback has been set on the condition variable, it is called
		394	immediately from within send.
		395
		396	Any arguments passed to the C<send> call will be returned by all
		397	future C<< ->recv >> calls.
		398
		399	Condition variables are overloaded so one can call them directly (as a
		400	code reference). Calling them directly is the same as calling C<send>.
		401
		402	=item $cv->croak ($error)
		403
		404	Similar to send, but causes all call's to C<< ->recv >> to invoke
		405	C<Carp::croak> with the given error message/object/scalar.
		406
		407	This can be used to signal any errors to the condition variable
		408	user/consumer.
		409
		410	=item $cv->begin ([group callback])
		411
329	=item $cv->wait	412	=item $cv->end
330		413
331	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	414	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		415
		416	These two methods can be used to combine many transactions/events into
		417	one. For example, a function that pings many hosts in parallel might want
		418	to use a condition variable for the whole process.
		419
		420	Every call to C<< ->begin >> will increment a counter, and every call to
		421	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		422	>>, the (last) callback passed to C<begin> will be executed. That callback
		423	is I<supposed> to call C<< ->send >>, but that is not required. If no
		424	callback was set, C<send> will be called without any arguments.
		425
		426	Let's clarify this with the ping example:
		427
		428	my $cv = AnyEvent->condvar;
		429
		430	my %result;
		431	$cv->begin (sub { $cv->send (\%result) });
		432
		433	for my $host (@list_of_hosts) {
		434	$cv->begin;
		435	ping_host_then_call_callback $host, sub {
		436	$result{$host} = ...;
		437	$cv->end;
		438	};
		439	}
		440
		441	$cv->end;
		442
		443	This code fragment supposedly pings a number of hosts and calls
		444	C<send> after results for all then have have been gathered - in any
		445	order. To achieve this, the code issues a call to C<begin> when it starts
		446	each ping request and calls C<end> when it has received some result for
		447	it. Since C<begin> and C<end> only maintain a counter, the order in which
		448	results arrive is not relevant.
		449
		450	There is an additional bracketing call to C<begin> and C<end> outside the
		451	loop, which serves two important purposes: first, it sets the callback
		452	to be called once the counter reaches C<0>, and second, it ensures that
		453	C<send> is called even when C<no> hosts are being pinged (the loop
		454	doesn't execute once).
		455
		456	This is the general pattern when you "fan out" into multiple subrequests:
		457	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		458	is called at least once, and then, for each subrequest you start, call
		459	C<begin> and for each subrequest you finish, call C<end>.
		460
		461	=back
		462
		463	=head3 METHODS FOR CONSUMERS
		464
		465	These methods should only be used by the consuming side, i.e. the
		466	code awaits the condition.
		467
		468	=over 4
		469
		470	=item $cv->recv
		471
		472	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
332	called on c<$cv>, while servicing other watchers normally.	473	>> methods have been called on c<$cv>, while servicing other watchers
		474	normally.
333		475
334	You can only wait once on a condition - additional calls will return	476	You can only wait once on a condition - additional calls are valid but
335	immediately.	477	will return immediately.
		478
		479	If an error condition has been set by calling C<< ->croak >>, then this
		480	function will call C<croak>.
		481
		482	In list context, all parameters passed to C<send> will be returned,
		483	in scalar context only the first one will be returned.
336		484
337	Not all event models support a blocking wait - some die in that case	485	Not all event models support a blocking wait - some die in that case
338	(programs might want to do that to stay interactive), so I<if you are	486	(programs might want to do that to stay interactive), so I<if you are
339	using this from a module, never require a blocking wait>, but let the	487	using this from a module, never require a blocking wait>, but let the
340	caller decide whether the call will block or not (for example, by coupling	488	caller decide whether the call will block or not (for example, by coupling
341	condition variables with some kind of request results and supporting	489	condition variables with some kind of request results and supporting
342	callbacks so the caller knows that getting the result will not block,	490	callbacks so the caller knows that getting the result will not block,
343	while still suppporting blocking waits if the caller so desires).	491	while still supporting blocking waits if the caller so desires).
344		492
345	Another reason I<never> to C<< ->wait >> in a module is that you cannot	493	Another reason I<never> to C<< ->recv >> in a module is that you cannot
346	sensibly have two C<< ->wait >>'s in parallel, as that would require	494	sensibly have two C<< ->recv >>'s in parallel, as that would require
347	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	495	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
348	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	496	can supply.
349	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
350	from different coroutines, however).
351		497
352	=item $cv->broadcast	498	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		499	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		500	versions and also integrates coroutines into AnyEvent, making blocking
		501	C<< ->recv >> calls perfectly safe as long as they are done from another
		502	coroutine (one that doesn't run the event loop).
353		503
354	Flag the condition as ready - a running C<< ->wait >> and all further	504	You can ensure that C<< -recv >> never blocks by setting a callback and
355	calls to C<wait> will (eventually) return after this method has been	505	only calling C<< ->recv >> from within that callback (or at a later
356	called. If nobody is waiting the broadcast will be remembered..	506	time). This will work even when the event loop does not support blocking
		507	waits otherwise.
		508
		509	=item $bool = $cv->ready
		510
		511	Returns true when the condition is "true", i.e. whether C<send> or
		512	C<croak> have been called.
		513
		514	=item $cb = $cv->cb ([new callback])
		515
		516	This is a mutator function that returns the callback set and optionally
		517	replaces it before doing so.
		518
		519	The callback will be called when the condition becomes "true", i.e. when
		520	C<send> or C<croak> are called. Calling C<recv> inside the callback
		521	or at any later time is guaranteed not to block.
357		522
358	=back	523	=back
359
360	Example:
361
362	# wait till the result is ready
363	my $result_ready = AnyEvent->condvar;
364
365	# do something such as adding a timer
366	# or socket watcher the calls $result_ready->broadcast
367	# when the "result" is ready.
368	# in this case, we simply use a timer:
369	my $w = AnyEvent->timer (
370	after => 1,
371	cb => sub { $result_ready->broadcast },
372	);
373
374	# this "blocks" (while handling events) till the watcher
375	# calls broadcast
376	$result_ready->wait;
377		524
378	=head1 GLOBAL VARIABLES AND FUNCTIONS	525	=head1 GLOBAL VARIABLES AND FUNCTIONS
379		526
380	=over 4	527	=over 4
381		528
…		…
387	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	534	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
388	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	535	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
389		536
390	The known classes so far are:	537	The known classes so far are:
391		538
392	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
393	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
394	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	539	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
395	AnyEvent::Impl::Event based on Event, second best choice.	540	AnyEvent::Impl::Event based on Event, second best choice.
		541	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
396	AnyEvent::Impl::Glib based on Glib, third-best choice.	542	AnyEvent::Impl::Glib based on Glib, third-best choice.
397	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
398	AnyEvent::Impl::Tk based on Tk, very bad choice.	543	AnyEvent::Impl::Tk based on Tk, very bad choice.
399	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	544	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
400	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	545	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
401	AnyEvent::Impl::POE based on POE, not generic enough for full support.	546	AnyEvent::Impl::POE based on POE, not generic enough for full support.
402		547
…		…
415	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	560	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
416	if necessary. You should only call this function right before you would	561	if necessary. You should only call this function right before you would
417	have created an AnyEvent watcher anyway, that is, as late as possible at	562	have created an AnyEvent watcher anyway, that is, as late as possible at
418	runtime.	563	runtime.
419		564
		565	=item $guard = AnyEvent::post_detect { BLOCK }
		566
		567	Arranges for the code block to be executed as soon as the event model is
		568	autodetected (or immediately if this has already happened).
		569
		570	If called in scalar or list context, then it creates and returns an object
		571	that automatically removes the callback again when it is destroyed. See
		572	L<Coro::BDB> for a case where this is useful.
		573
		574	=item @AnyEvent::post_detect
		575
		576	If there are any code references in this array (you can C<push> to it
		577	before or after loading AnyEvent), then they will called directly after
		578	the event loop has been chosen.
		579
		580	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		581	if it contains a true value then the event loop has already been detected,
		582	and the array will be ignored.
		583
		584	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		585
420	=back	586	=back
421		587
422	=head1 WHAT TO DO IN A MODULE	588	=head1 WHAT TO DO IN A MODULE
423		589
424	As a module author, you should C<use AnyEvent> and call AnyEvent methods	590	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
427	Be careful when you create watchers in the module body - AnyEvent will	593	Be careful when you create watchers in the module body - AnyEvent will
428	decide which event module to use as soon as the first method is called, so	594	decide which event module to use as soon as the first method is called, so
429	by calling AnyEvent in your module body you force the user of your module	595	by calling AnyEvent in your module body you force the user of your module
430	to load the event module first.	596	to load the event module first.
431		597
432	Never call C<< ->wait >> on a condition variable unless you I<know> that	598	Never call C<< ->recv >> on a condition variable unless you I<know> that
433	the C<< ->broadcast >> method has been called on it already. This is	599	the C<< ->send >> method has been called on it already. This is
434	because it will stall the whole program, and the whole point of using	600	because it will stall the whole program, and the whole point of using
435	events is to stay interactive.	601	events is to stay interactive.
436		602
437	It is fine, however, to call C<< ->wait >> when the user of your module	603	It is fine, however, to call C<< ->recv >> when the user of your module
438	requests it (i.e. if you create a http request object ad have a method	604	requests it (i.e. if you create a http request object ad have a method
439	called C<results> that returns the results, it should call C<< ->wait >>	605	called C<results> that returns the results, it should call C<< ->recv >>
440	freely, as the user of your module knows what she is doing. always).	606	freely, as the user of your module knows what she is doing. always).
441		607
442	=head1 WHAT TO DO IN THE MAIN PROGRAM	608	=head1 WHAT TO DO IN THE MAIN PROGRAM
443		609
444	There will always be a single main program - the only place that should	610	There will always be a single main program - the only place that should
…		…
446		612
447	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	613	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
448	do anything special (it does not need to be event-based) and let AnyEvent	614	do anything special (it does not need to be event-based) and let AnyEvent
449	decide which implementation to chose if some module relies on it.	615	decide which implementation to chose if some module relies on it.
450		616
451	If the main program relies on a specific event model. For example, in	617	If the main program relies on a specific event model - for example, in
452	Gtk2 programs you have to rely on the Glib module. You should load the	618	Gtk2 programs you have to rely on the Glib module - you should load the
453	event module before loading AnyEvent or any module that uses it: generally	619	event module before loading AnyEvent or any module that uses it: generally
454	speaking, you should load it as early as possible. The reason is that	620	speaking, you should load it as early as possible. The reason is that
455	modules might create watchers when they are loaded, and AnyEvent will	621	modules might create watchers when they are loaded, and AnyEvent will
456	decide on the event model to use as soon as it creates watchers, and it	622	decide on the event model to use as soon as it creates watchers, and it
457	might chose the wrong one unless you load the correct one yourself.	623	might chose the wrong one unless you load the correct one yourself.
458		624
459	You can chose to use a rather inefficient pure-perl implementation by	625	You can chose to use a pure-perl implementation by loading the
460	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	626	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
461	behaviour everywhere, but letting AnyEvent chose is generally better.	627	everywhere, but letting AnyEvent chose the model is generally better.
		628
		629	=head2 MAINLOOP EMULATION
		630
		631	Sometimes (often for short test scripts, or even standalone programs who
		632	only want to use AnyEvent), you do not want to run a specific event loop.
		633
		634	In that case, you can use a condition variable like this:
		635
		636	AnyEvent->condvar->recv;
		637
		638	This has the effect of entering the event loop and looping forever.
		639
		640	Note that usually your program has some exit condition, in which case
		641	it is better to use the "traditional" approach of storing a condition
		642	variable somewhere, waiting for it, and sending it when the program should
		643	exit cleanly.
		644
		645
		646	=head1 OTHER MODULES
		647
		648	The following is a non-exhaustive list of additional modules that use
		649	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		650	in the same program. Some of the modules come with AnyEvent, some are
		651	available via CPAN.
		652
		653	=over 4
		654
		655	=item L<AnyEvent::Util>
		656
		657	Contains various utility functions that replace often-used but blocking
		658	functions such as C<inet_aton> by event-/callback-based versions.
		659
		660	=item L<AnyEvent::Handle>
		661
		662	Provide read and write buffers and manages watchers for reads and writes.
		663
		664	=item L<AnyEvent::Socket>
		665
		666	Provides various utility functions for (internet protocol) sockets,
		667	addresses and name resolution. Also functions to create non-blocking tcp
		668	connections or tcp servers, with IPv6 and SRV record support and more.
		669
		670	=item L<AnyEvent::DNS>
		671
		672	Provides rich asynchronous DNS resolver capabilities.
		673
		674	=item L<AnyEvent::HTTPD>
		675
		676	Provides a simple web application server framework.
		677
		678	=item L<AnyEvent::FastPing>
		679
		680	The fastest ping in the west.
		681
		682	=item L<Net::IRC3>
		683
		684	AnyEvent based IRC client module family.
		685
		686	=item L<Net::XMPP2>
		687
		688	AnyEvent based XMPP (Jabber protocol) module family.
		689
		690	=item L<Net::FCP>
		691
		692	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		693	of AnyEvent.
		694
		695	=item L<Event::ExecFlow>
		696
		697	High level API for event-based execution flow control.
		698
		699	=item L<Coro>
		700
		701	Has special support for AnyEvent via L<Coro::AnyEvent>.
		702
		703	=item L<AnyEvent::AIO>, L<IO::AIO>
		704
		705	Truly asynchronous I/O, should be in the toolbox of every event
		706	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
		707	together.
		708
		709	=item L<AnyEvent::BDB>, L<BDB>
		710
		711	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
		712	IO::AIO and AnyEvent together.
		713
		714	=item L<IO::Lambda>
		715
		716	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		717
		718	=back
462		719
463	=cut	720	=cut
464		721
465	package AnyEvent;	722	package AnyEvent;
466		723
467	no warnings;	724	no warnings;
468	use strict;	725	use strict;
469		726
470	use Carp;	727	use Carp;
471		728
472	our $VERSION = '3.3';	729	our $VERSION = '4.03';
473	our $MODEL;	730	our $MODEL;
474		731
475	our $AUTOLOAD;	732	our $AUTOLOAD;
476	our @ISA;	733	our @ISA;
477		734
478	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	735	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
479		736
480	our @REGISTRY;	737	our @REGISTRY;
481		738
		739	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2)
		740
		741	{
		742	my $idx;
		743	$PROTOCOL{$_} = ++$idx
		744	for split /\s,\s/, $ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		745	}
		746
482	my @models = (	747	my @models = (
483	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
484	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
485	[EV:: => AnyEvent::Impl::EV::],	748	[EV:: => AnyEvent::Impl::EV::],
486	[Event:: => AnyEvent::Impl::Event::],	749	[Event:: => AnyEvent::Impl::Event::],
487	[Glib:: => AnyEvent::Impl::Glib::],
488	[Tk:: => AnyEvent::Impl::Tk::],	750	[Tk:: => AnyEvent::Impl::Tk::],
489	[Wx:: => AnyEvent::Impl::POE::],	751	[Wx:: => AnyEvent::Impl::POE::],
490	[Prima:: => AnyEvent::Impl::POE::],	752	[Prima:: => AnyEvent::Impl::POE::],
491	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	753	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
492	# everything below here will not be autoprobed as the pureperl backend should work everywhere	754	# everything below here will not be autoprobed as the pureperl backend should work everywhere
		755	[Glib:: => AnyEvent::Impl::Glib::],
493	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	756	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
494	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	757	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
495	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	758	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
496	);	759	);
497		760
498	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	761	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
		762
		763	our @post_detect;
		764
		765	sub post_detect(&) {
		766	my ($cb) = @_;
		767
		768	if ($MODEL) {
		769	$cb->();
		770
		771	1
		772	} else {
		773	push @post_detect, $cb;
		774
		775	defined wantarray
		776	? bless \$cb, "AnyEvent::Util::PostDetect"
		777	: ()
		778	}
		779	}
		780
		781	sub AnyEvent::Util::PostDetect::DESTROY {
		782	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		783	}
499		784
500	sub detect() {	785	sub detect() {
501	unless ($MODEL) {	786	unless ($MODEL) {
502	no strict 'refs';	787	no strict 'refs';
503		788
…		…
537	last;	822	last;
538	}	823	}
539	}	824	}
540		825
541	$MODEL	826	$MODEL
542	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.";	827	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
543	}	828	}
544	}	829	}
545		830
546	unshift @ISA, $MODEL;	831	unshift @ISA, $MODEL;
547	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	832	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		833
		834	(shift @post_detect)->() while @post_detect;
548	}	835	}
549		836
550	$MODEL	837	$MODEL
551	}	838	}
552		839
…		…
562	$class->$func (@_);	849	$class->$func (@_);
563	}	850	}
564		851
565	package AnyEvent::Base;	852	package AnyEvent::Base;
566		853
567	# default implementation for ->condvar, ->wait, ->broadcast	854	# default implementation for ->condvar
568		855
569	sub condvar {	856	sub condvar {
570	bless \my $flag, "AnyEvent::Base::CondVar"	857	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
571	}
572
573	sub AnyEvent::Base::CondVar::broadcast {
574	${$_[0]}++;
575	}
576
577	sub AnyEvent::Base::CondVar::wait {
578	AnyEvent->one_event while !${$_[0]};
579	}	858	}
580		859
581	# default implementation for ->signal	860	# default implementation for ->signal
582		861
583	our %SIG_CB;	862	our %SIG_CB;
…		…
657	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	936	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
658		937
659	undef $CHLD_W unless keys %PID_CB;	938	undef $CHLD_W unless keys %PID_CB;
660	}	939	}
661		940
		941	package AnyEvent::CondVar;
		942
		943	our @ISA = AnyEvent::CondVar::Base::;
		944
		945	package AnyEvent::CondVar::Base;
		946
		947	use overload
		948	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		949	fallback => 1;
		950
		951	sub _send {
		952	# nop
		953	}
		954
		955	sub send {
		956	my $cv = shift;
		957	$cv->{_ae_sent} = [@_];
		958	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		959	$cv->_send;
		960	}
		961
		962	sub croak {
		963	$_[0]{_ae_croak} = $_[1];
		964	$_[0]->send;
		965	}
		966
		967	sub ready {
		968	$_[0]{_ae_sent}
		969	}
		970
		971	sub _wait {
		972	AnyEvent->one_event while !$_[0]{_ae_sent};
		973	}
		974
		975	sub recv {
		976	$_[0]->_wait;
		977
		978	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		979	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		980	}
		981
		982	sub cb {
		983	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		984	$_[0]{_ae_cb}
		985	}
		986
		987	sub begin {
		988	++$_[0]{_ae_counter};
		989	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		990	}
		991
		992	sub end {
		993	return if --$_[0]{_ae_counter};
		994	&{ $_[0]{_ae_end_cb} \|\| sub { $_[0]->send } };
		995	}
		996
		997	# undocumented/compatibility with pre-3.4
		998	*broadcast = \&send;
		999	*wait = \&_wait;
		1000
662	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1001	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
663		1002
664	This is an advanced topic that you do not normally need to use AnyEvent in	1003	This is an advanced topic that you do not normally need to use AnyEvent in
665	a module. This section is only of use to event loop authors who want to	1004	a module. This section is only of use to event loop authors who want to
666	provide AnyEvent compatibility.	1005	provide AnyEvent compatibility.
…		…
722	model it chooses.	1061	model it chooses.
723		1062
724	=item C<PERL_ANYEVENT_MODEL>	1063	=item C<PERL_ANYEVENT_MODEL>
725		1064
726	This can be used to specify the event model to be used by AnyEvent, before	1065	This can be used to specify the event model to be used by AnyEvent, before
727	autodetection and -probing kicks in. It must be a string consisting	1066	auto detection and -probing kicks in. It must be a string consisting
728	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1067	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
729	and the resulting module name is loaded and if the load was successful,	1068	and the resulting module name is loaded and if the load was successful,
730	used as event model. If it fails to load AnyEvent will proceed with	1069	used as event model. If it fails to load AnyEvent will proceed with
731	autodetection and -probing.	1070	auto detection and -probing.
732		1071
733	This functionality might change in future versions.	1072	This functionality might change in future versions.
734		1073
735	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1074	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
736	could start your program like this:	1075	could start your program like this:
737		1076
738	PERL_ANYEVENT_MODEL=Perl perl ...	1077	PERL_ANYEVENT_MODEL=Perl perl ...
		1078
		1079	=item C<PERL_ANYEVENT_PROTOCOLS>
		1080
		1081	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1082	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1083	of auto probing).
		1084
		1085	Must be set to a comma-separated list of protocols or address families,
		1086	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1087	used, and preference will be given to protocols mentioned earlier in the
		1088	list.
		1089
		1090	This variable can effectively be used for denial-of-service attacks
		1091	against local programs (e.g. when setuid), although the impact is likely
		1092	small, as the program has to handle connection errors already-
		1093
		1094	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1095	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1096	- only support IPv4, never try to resolve or contact IPv6
		1097	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1098	IPv6, but prefer IPv6 over IPv4.
		1099
		1100	=item C<PERL_ANYEVENT_EDNS0>
		1101
		1102	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1103	for DNS. This extension is generally useful to reduce DNS traffic, but
		1104	some (broken) firewalls drop such DNS packets, which is why it is off by
		1105	default.
		1106
		1107	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1108	EDNS0 in its DNS requests.
739		1109
740	=back	1110	=back
741		1111
742	=head1 EXAMPLE PROGRAM	1112	=head1 EXAMPLE PROGRAM
743		1113
…		…
754	poll => 'r',	1124	poll => 'r',
755	cb => sub {	1125	cb => sub {
756	warn "io event <$_[0]>\n"; # will always output <r>	1126	warn "io event <$_[0]>\n"; # will always output <r>
757	chomp (my $input = <STDIN>); # read a line	1127	chomp (my $input = <STDIN>); # read a line
758	warn "read: $input\n"; # output what has been read	1128	warn "read: $input\n"; # output what has been read
759	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1129	$cv->send if $input =~ /^q/i; # quit program if /^q/i
760	},	1130	},
761	);	1131	);
762		1132
763	my $time_watcher; # can only be used once	1133	my $time_watcher; # can only be used once
764		1134
…		…
769	});	1139	});
770	}	1140	}
771		1141
772	new_timer; # create first timer	1142	new_timer; # create first timer
773		1143
774	$cv->wait; # wait until user enters /^q/i	1144	$cv->recv; # wait until user enters /^q/i
775		1145
776	=head1 REAL-WORLD EXAMPLE	1146	=head1 REAL-WORLD EXAMPLE
777		1147
778	Consider the L<Net::FCP> module. It features (among others) the following	1148	Consider the L<Net::FCP> module. It features (among others) the following
779	API calls, which are to freenet what HTTP GET requests are to http:	1149	API calls, which are to freenet what HTTP GET requests are to http:
…		…
829	syswrite $txn->{fh}, $txn->{request}	1199	syswrite $txn->{fh}, $txn->{request}
830	or die "connection or write error";	1200	or die "connection or write error";
831	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1201	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
832		1202
833	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1203	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
834	result and signals any possible waiters that the request ahs finished:	1204	result and signals any possible waiters that the request has finished:
835		1205
836	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1206	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
837		1207
838	if (end-of-file or data complete) {	1208	if (end-of-file or data complete) {
839	$txn->{result} = $txn->{buf};	1209	$txn->{result} = $txn->{buf};
840	$txn->{finished}->broadcast;	1210	$txn->{finished}->send;
841	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1211	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
842	}	1212	}
843		1213
844	The C<result> method, finally, just waits for the finished signal (if the	1214	The C<result> method, finally, just waits for the finished signal (if the
845	request was already finished, it doesn't wait, of course, and returns the	1215	request was already finished, it doesn't wait, of course, and returns the
846	data:	1216	data:
847		1217
848	$txn->{finished}->wait;	1218	$txn->{finished}->recv;
849	return $txn->{result};	1219	return $txn->{result};
850		1220
851	The actual code goes further and collects all errors (C<die>s, exceptions)	1221	The actual code goes further and collects all errors (C<die>s, exceptions)
852	that occured during request processing. The C<result> method detects	1222	that occurred during request processing. The C<result> method detects
853	whether an exception as thrown (it is stored inside the $txn object)	1223	whether an exception as thrown (it is stored inside the $txn object)
854	and just throws the exception, which means connection errors and other	1224	and just throws the exception, which means connection errors and other
855	problems get reported tot he code that tries to use the result, not in a	1225	problems get reported tot he code that tries to use the result, not in a
856	random callback.	1226	random callback.
857		1227
…		…
888		1258
889	my $quit = AnyEvent->condvar;	1259	my $quit = AnyEvent->condvar;
890		1260
891	$fcp->txn_client_get ($url)->cb (sub {	1261	$fcp->txn_client_get ($url)->cb (sub {
892	...	1262	...
893	$quit->broadcast;	1263	$quit->send;
894	});	1264	});
895		1265
896	$quit->wait;	1266	$quit->recv;
897		1267
898		1268
899	=head1 BENCHMARKS	1269	=head1 BENCHMARKS
900		1270
901	To give you an idea of the performance and overheads that AnyEvent adds	1271	To give you an idea of the performance and overheads that AnyEvent adds
…		…
903	of various event loops I prepared some benchmarks.	1273	of various event loops I prepared some benchmarks.
904		1274
905	=head2 BENCHMARKING ANYEVENT OVERHEAD	1275	=head2 BENCHMARKING ANYEVENT OVERHEAD
906		1276
907	Here is a benchmark of various supported event models used natively and	1277	Here is a benchmark of various supported event models used natively and
908	through anyevent. The benchmark creates a lot of timers (with a zero	1278	through AnyEvent. The benchmark creates a lot of timers (with a zero
909	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1279	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
910	which it is), lets them fire exactly once and destroys them again.	1280	which it is), lets them fire exactly once and destroys them again.
911		1281
912	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1282	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
913	distribution.	1283	distribution.
…		…
930	all watchers, to avoid adding memory overhead. That means closure creation	1300	all watchers, to avoid adding memory overhead. That means closure creation
931	and memory usage is not included in the figures.	1301	and memory usage is not included in the figures.
932		1302
933	I<invoke> is the time, in microseconds, used to invoke a simple	1303	I<invoke> is the time, in microseconds, used to invoke a simple
934	callback. The callback simply counts down a Perl variable and after it was	1304	callback. The callback simply counts down a Perl variable and after it was
935	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1305	invoked "watcher" times, it would C<< ->send >> a condvar once to
936	signal the end of this phase.	1306	signal the end of this phase.
937		1307
938	I<destroy> is the time, in microseconds, that it takes to destroy a single	1308	I<destroy> is the time, in microseconds, that it takes to destroy a single
939	watcher.	1309	watcher.
940		1310
…		…
944	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1314	EV/EV 400000 244 0.56 0.46 0.31 EV native interface
945	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1315	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers
946	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1316	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal
947	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1317	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation
948	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1318	Event/Event 16000 516 31.88 31.30 0.85 Event native interface
949	Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers	1319	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers
950	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1320	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour
951	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1321	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers
952	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1322	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event
953	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1323	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select
954		1324
…		…
963		1333
964	Also, note that the number of watchers usually has a nonlinear effect on	1334	Also, note that the number of watchers usually has a nonlinear effect on
965	overall speed, that is, creating twice as many watchers doesn't take twice	1335	overall speed, that is, creating twice as many watchers doesn't take twice
966	the time - usually it takes longer. This puts event loops tested with a	1336	the time - usually it takes longer. This puts event loops tested with a
967	higher number of watchers at a disadvantage.	1337	higher number of watchers at a disadvantage.
		1338
		1339	To put the range of results into perspective, consider that on the
		1340	benchmark machine, handling an event takes roughly 1600 CPU cycles with
		1341	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
		1342	cycles with POE.
968		1343
969	C<EV> is the sole leader regarding speed and memory use, which are both	1344	C<EV> is the sole leader regarding speed and memory use, which are both
970	maximal/minimal, respectively. Even when going through AnyEvent, it uses	1345	maximal/minimal, respectively. Even when going through AnyEvent, it uses
971	far less memory than any other event loop and is still faster than Event	1346	far less memory than any other event loop and is still faster than Event
972	natively.	1347	natively.
…		…
995	file descriptor is dup()ed for each watcher. This shows that the dup()	1370	file descriptor is dup()ed for each watcher. This shows that the dup()
996	employed by some adaptors is not a big performance issue (it does incur a	1371	employed by some adaptors is not a big performance issue (it does incur a
997	hidden memory cost inside the kernel which is not reflected in the figures	1372	hidden memory cost inside the kernel which is not reflected in the figures
998	above).	1373	above).
999		1374
1000	C<POE>, regardless of underlying event loop (whether using its pure	1375	C<POE>, regardless of underlying event loop (whether using its pure perl
1001	perl select-based backend or the Event module, the POE-EV backend	1376	select-based backend or the Event module, the POE-EV backend couldn't
1002	couldn't be tested because it wasn't working) shows abysmal performance	1377	be tested because it wasn't working) shows abysmal performance and
1003	and memory usage: Watchers use almost 30 times as much memory as	1378	memory usage with AnyEvent: Watchers use almost 30 times as much memory
1004	EV watchers, and 10 times as much memory as Event (the high memory	1379	as EV watchers, and 10 times as much memory as Event (the high memory
1005	requirements are caused by requiring a session for each watcher). Watcher	1380	requirements are caused by requiring a session for each watcher). Watcher
1006	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1381	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1382	implementation.
		1383
1007	implementation. The design of the POE adaptor class in AnyEvent can not	1384	The design of the POE adaptor class in AnyEvent can not really account
1008	really account for this, as session creation overhead is small compared	1385	for the performance issues, though, as session creation overhead is
1009	to execution of the state machine, which is coded pretty optimally within	1386	small compared to execution of the state machine, which is coded pretty
1010	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1387	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1388	using multiple sessions is not a good approach, especially regarding
		1389	memory usage, even the author of POE could not come up with a faster
		1390	design).
1011		1391
1012	=head3 Summary	1392	=head3 Summary
1013		1393
1014	=over 4	1394	=over 4
1015		1395
…		…
1026		1406
1027	=back	1407	=back
1028		1408
1029	=head2 BENCHMARKING THE LARGE SERVER CASE	1409	=head2 BENCHMARKING THE LARGE SERVER CASE
1030		1410
1031	This benchmark atcually benchmarks the event loop itself. It works by	1411	This benchmark actually benchmarks the event loop itself. It works by
1032	creating a number of "servers": each server consists of a socketpair, a	1412	creating a number of "servers": each server consists of a socket pair, a
1033	timeout watcher that gets reset on activity (but never fires), and an I/O	1413	timeout watcher that gets reset on activity (but never fires), and an I/O
1034	watcher waiting for input on one side of the socket. Each time the socket	1414	watcher waiting for input on one side of the socket. Each time the socket
1035	watcher reads a byte it will write that byte to a random other "server".	1415	watcher reads a byte it will write that byte to a random other "server".
1036		1416
1037	The effect is that there will be a lot of I/O watchers, only part of which	1417	The effect is that there will be a lot of I/O watchers, only part of which
1038	are active at any one point (so there is a constant number of active	1418	are active at any one point (so there is a constant number of active
1039	fds for each loop iterstaion, but which fds these are is random). The	1419	fds for each loop iteration, but which fds these are is random). The
1040	timeout is reset each time something is read because that reflects how	1420	timeout is reset each time something is read because that reflects how
1041	most timeouts work (and puts extra pressure on the event loops).	1421	most timeouts work (and puts extra pressure on the event loops).
1042		1422
1043	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1423	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1044	(1%) are active. This mirrors the activity of large servers with many	1424	(1%) are active. This mirrors the activity of large servers with many
1045	connections, most of which are idle at any one point in time.	1425	connections, most of which are idle at any one point in time.
1046		1426
1047	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1427	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1048	distribution.	1428	distribution.
…		…
1050	=head3 Explanation of the columns	1430	=head3 Explanation of the columns
1051		1431
1052	I<sockets> is the number of sockets, and twice the number of "servers" (as	1432	I<sockets> is the number of sockets, and twice the number of "servers" (as
1053	each server has a read and write socket end).	1433	each server has a read and write socket end).
1054		1434
1055	I<create> is the time it takes to create a socketpair (which is	1435	I<create> is the time it takes to create a socket pair (which is
1056	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1436	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1057		1437
1058	I<request>, the most important value, is the time it takes to handle a	1438	I<request>, the most important value, is the time it takes to handle a
1059	single "request", that is, reading the token from the pipe and forwarding	1439	single "request", that is, reading the token from the pipe and forwarding
1060	it to another server. This includes deleting the old timeout and creating	1440	it to another server. This includes deleting the old timeout and creating
…		…
1062		1442
1063	=head3 Results	1443	=head3 Results
1064		1444
1065	name sockets create request	1445	name sockets create request
1066	EV 20000 69.01 11.16	1446	EV 20000 69.01 11.16
1067	Perl 20000 75.28 112.76	1447	Perl 20000 73.32 35.87
1068	Event 20000 212.62 257.32	1448	Event 20000 212.62 257.32
1069	Glib 20000 651.16 1896.30	1449	Glib 20000 651.16 1896.30
1070	POE 20000 349.67 12317.24 uses POE::Loop::Event	1450	POE 20000 349.67 12317.24 uses POE::Loop::Event
1071		1451
1072	=head3 Discussion	1452	=head3 Discussion
…		…
1094		1474
1095	=head3 Summary	1475	=head3 Summary
1096		1476
1097	=over 4	1477	=over 4
1098		1478
1099	=item * The pure perl implementation performs extremely well, considering	1479	=item * The pure perl implementation performs extremely well.
1100	that it uses select.
1101		1480
1102	=item * Avoid Glib or POE in large projects where performance matters.	1481	=item * Avoid Glib or POE in large projects where performance matters.
1103		1482
1104	=back	1483	=back
1105		1484
…		…
1118		1497
1119	=head3 Results	1498	=head3 Results
1120		1499
1121	name sockets create request	1500	name sockets create request
1122	EV 16 20.00 6.54	1501	EV 16 20.00 6.54
		1502	Perl 16 25.75 12.62
1123	Event 16 81.27 35.86	1503	Event 16 81.27 35.86
1124	Glib 16 32.63 15.48	1504	Glib 16 32.63 15.48
1125	Perl 16 24.62 162.37
1126	POE 16 261.87 276.28 uses POE::Loop::Event	1505	POE 16 261.87 276.28 uses POE::Loop::Event
1127		1506
1128	=head3 Discussion	1507	=head3 Discussion
1129		1508
1130	The benchmark tries to test the performance of a typical small	1509	The benchmark tries to test the performance of a typical small
1131	server. While knowing how various event loops perform is interesting, keep	1510	server. While knowing how various event loops perform is interesting, keep
1132	in mind that their overhead in this case is usually not as important, due	1511	in mind that their overhead in this case is usually not as important, due
1133	to the small absolute number of watchers.	1512	to the small absolute number of watchers (that is, you need efficiency and
		1513	speed most when you have lots of watchers, not when you only have a few of
		1514	them).
1134		1515
1135	EV is again fastest.	1516	EV is again fastest.
1136		1517
1137	The C-based event loops Event and Glib come in second this time, as the	1518	Perl again comes second. It is noticeably faster than the C-based event
1138	overhead of running an iteration is much smaller in C than in Perl (little	1519	loops Event and Glib, although the difference is too small to really
1139	code to execute in the inner loop, and perl's function calling overhead is	1520	matter.
1140	high, and updating all the data structures is costly).
1141		1521
1142	The pure perl event loop is much slower, but still competitive.
1143
1144	POE also performs much better in this case, but is is stillf ar behind the	1522	POE also performs much better in this case, but is is still far behind the
1145	others.	1523	others.
1146		1524
1147	=head3 Summary	1525	=head3 Summary
1148		1526
1149	=over 4	1527	=over 4
…		…
1155		1533
1156		1534
1157	=head1 FORK	1535	=head1 FORK
1158		1536
1159	Most event libraries are not fork-safe. The ones who are usually are	1537	Most event libraries are not fork-safe. The ones who are usually are
1160	because they are so inefficient. Only L<EV> is fully fork-aware.	1538	because they rely on inefficient but fork-safe C<select> or C<poll>
		1539	calls. Only L<EV> is fully fork-aware.
1161		1540
1162	If you have to fork, you must either do so I<before> creating your first	1541	If you have to fork, you must either do so I<before> creating your first
1163	watcher OR you must not use AnyEvent at all in the child.	1542	watcher OR you must not use AnyEvent at all in the child.
1164		1543
1165		1544
…		…
1177		1556
1178	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1557	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1179		1558
1180	use AnyEvent;	1559	use AnyEvent;
1181		1560
		1561	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1562	be used to probe what backend is used and gain other information (which is
		1563	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
		1564
1182		1565
1183	=head1 SEE ALSO	1566	=head1 SEE ALSO
1184		1567
1185	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1568	Utility functions: L<AnyEvent::Util>.
1186	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1569
		1570	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1187	L<Event::Lib>, L<Qt>, L<POE>.	1571	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1188		1572
1189	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1573	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1190	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1574	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1191	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1575	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1192	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1576	L<AnyEvent::Impl::POE>.
1193		1577
		1578	Non-blocking file handles, sockets, TCP clients and
		1579	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1580
		1581	Asynchronous DNS: L<AnyEvent::DNS>.
		1582
		1583	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1584
1194	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1585	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1195		1586
1196		1587
1197	=head1 AUTHOR	1588	=head1 AUTHOR
1198		1589
1199	Marc Lehmann <schmorp@schmorp.de>	1590	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.95 by root, Sat Apr 26 11:06:45 2008 UTC vs. Revision 1.134 by root, Sun May 25 04:44:04 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.95 by root, Sat Apr 26 11:06:45 2008 UTC vs.
Revision 1.134 by root, Sun May 25 04:44:04 2008 UTC