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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.94 by root, Sat Apr 26 04:33:51 2008 UTC vs.
Revision 1.131 by root, Sat May 24 17:48:38 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
…		…
458		624
459	You can chose to use a rather inefficient pure-perl implementation by	625	You can chose to use a rather inefficient pure-perl implementation by
460	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	626	loading the C<AnyEvent::Impl::Perl> module, which gives you similar
461	behaviour everywhere, but letting AnyEvent chose is generally better.	627	behaviour everywhere, but letting AnyEvent chose is generally better.
462		628
		629	=head1 OTHER MODULES
		630
		631	The following is a non-exhaustive list of additional modules that use
		632	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		633	in the same program. Some of the modules come with AnyEvent, some are
		634	available via CPAN.
		635
		636	=over 4
		637
		638	=item L<AnyEvent::Util>
		639
		640	Contains various utility functions that replace often-used but blocking
		641	functions such as C<inet_aton> by event-/callback-based versions.
		642
		643	=item L<AnyEvent::Handle>
		644
		645	Provide read and write buffers and manages watchers for reads and writes.
		646
		647	=item L<AnyEvent::Socket>
		648
		649	Provides various utility functions for (internet protocol) sockets,
		650	addresses and name resolution. Also functions to create non-blocking tcp
		651	connections or tcp servers, with IPv6 and SRV record support and more.
		652
		653	=item L<AnyEvent::HTTPD>
		654
		655	Provides a simple web application server framework.
		656
		657	=item L<AnyEvent::DNS>
		658
		659	Provides rich asynchronous DNS resolver capabilities.
		660
		661	=item L<AnyEvent::FastPing>
		662
		663	The fastest ping in the west.
		664
		665	=item L<Net::IRC3>
		666
		667	AnyEvent based IRC client module family.
		668
		669	=item L<Net::XMPP2>
		670
		671	AnyEvent based XMPP (Jabber protocol) module family.
		672
		673	=item L<Net::FCP>
		674
		675	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		676	of AnyEvent.
		677
		678	=item L<Event::ExecFlow>
		679
		680	High level API for event-based execution flow control.
		681
		682	=item L<Coro>
		683
		684	Has special support for AnyEvent via L<Coro::AnyEvent>.
		685
		686	=item L<AnyEvent::AIO>, L<IO::AIO>
		687
		688	Truly asynchronous I/O, should be in the toolbox of every event
		689	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
		690	together.
		691
		692	=item L<AnyEvent::BDB>, L<BDB>
		693
		694	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
		695	IO::AIO and AnyEvent together.
		696
		697	=item L<IO::Lambda>
		698
		699	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
		700
		701	=back
		702
463	=cut	703	=cut
464		704
465	package AnyEvent;	705	package AnyEvent;
466		706
467	no warnings;	707	no warnings;
468	use strict;	708	use strict;
469		709
470	use Carp;	710	use Carp;
471		711
472	our $VERSION = '3.3';	712	our $VERSION = '4.0';
473	our $MODEL;	713	our $MODEL;
474		714
475	our $AUTOLOAD;	715	our $AUTOLOAD;
476	our @ISA;	716	our @ISA;
477		717
478	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	718	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
479		719
480	our @REGISTRY;	720	our @REGISTRY;
481		721
		722	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2)
		723
		724	{
		725	my $idx;
		726	$PROTOCOL{$_} = ++$idx
		727	for split /\s,\s/, $ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		728	}
		729
482	my @models = (	730	my @models = (
483	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
484	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
485	[EV:: => AnyEvent::Impl::EV::],	731	[EV:: => AnyEvent::Impl::EV::],
486	[Event:: => AnyEvent::Impl::Event::],	732	[Event:: => AnyEvent::Impl::Event::],
487	[Glib:: => AnyEvent::Impl::Glib::],
488	[Tk:: => AnyEvent::Impl::Tk::],	733	[Tk:: => AnyEvent::Impl::Tk::],
489	[Wx:: => AnyEvent::Impl::POE::],	734	[Wx:: => AnyEvent::Impl::POE::],
490	[Prima:: => AnyEvent::Impl::POE::],	735	[Prima:: => AnyEvent::Impl::POE::],
491	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	736	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
492	# everything below here will not be autoprobed as the pureperl backend should work everywhere	737	# everything below here will not be autoprobed as the pureperl backend should work everywhere
		738	[Glib:: => AnyEvent::Impl::Glib::],
493	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	739	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
494	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	740	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
495	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	741	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
496	);	742	);
497		743
498	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	744	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
		745
		746	our @post_detect;
		747
		748	sub post_detect(&) {
		749	my ($cb) = @_;
		750
		751	if ($MODEL) {
		752	$cb->();
		753
		754	1
		755	} else {
		756	push @post_detect, $cb;
		757
		758	defined wantarray
		759	? bless \$cb, "AnyEvent::Util::PostDetect"
		760	: ()
		761	}
		762	}
		763
		764	sub AnyEvent::Util::PostDetect::DESTROY {
		765	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		766	}
499		767
500	sub detect() {	768	sub detect() {
501	unless ($MODEL) {	769	unless ($MODEL) {
502	no strict 'refs';	770	no strict 'refs';
503		771
…		…
537	last;	805	last;
538	}	806	}
539	}	807	}
540		808
541	$MODEL	809	$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.";	810	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
543	}	811	}
544	}	812	}
545		813
546	unshift @ISA, $MODEL;	814	unshift @ISA, $MODEL;
547	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	815	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		816
		817	(shift @post_detect)->() while @post_detect;
548	}	818	}
549		819
550	$MODEL	820	$MODEL
551	}	821	}
552		822
…		…
562	$class->$func (@_);	832	$class->$func (@_);
563	}	833	}
564		834
565	package AnyEvent::Base;	835	package AnyEvent::Base;
566		836
567	# default implementation for ->condvar, ->wait, ->broadcast	837	# default implementation for ->condvar
568		838
569	sub condvar {	839	sub condvar {
570	bless \my $flag, "AnyEvent::Base::CondVar"	840	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	}	841	}
580		842
581	# default implementation for ->signal	843	# default implementation for ->signal
582		844
583	our %SIG_CB;	845	our %SIG_CB;
…		…
657	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	919	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
658		920
659	undef $CHLD_W unless keys %PID_CB;	921	undef $CHLD_W unless keys %PID_CB;
660	}	922	}
661		923
		924	package AnyEvent::CondVar;
		925
		926	our @ISA = AnyEvent::CondVar::Base::;
		927
		928	package AnyEvent::CondVar::Base;
		929
		930	use overload
		931	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		932	fallback => 1;
		933
		934	sub _send {
		935	# nop
		936	}
		937
		938	sub send {
		939	my $cv = shift;
		940	$cv->{_ae_sent} = [@_];
		941	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		942	$cv->_send;
		943	}
		944
		945	sub croak {
		946	$_[0]{_ae_croak} = $_[1];
		947	$_[0]->send;
		948	}
		949
		950	sub ready {
		951	$_[0]{_ae_sent}
		952	}
		953
		954	sub _wait {
		955	AnyEvent->one_event while !$_[0]{_ae_sent};
		956	}
		957
		958	sub recv {
		959	$_[0]->_wait;
		960
		961	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		962	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		963	}
		964
		965	sub cb {
		966	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		967	$_[0]{_ae_cb}
		968	}
		969
		970	sub begin {
		971	++$_[0]{_ae_counter};
		972	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		973	}
		974
		975	sub end {
		976	return if --$_[0]{_ae_counter};
		977	&{ $_[0]{_ae_end_cb} \|\| sub { $_[0]->send } };
		978	}
		979
		980	# undocumented/compatibility with pre-3.4
		981	*broadcast = \&send;
		982	*wait = \&_wait;
		983
662	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	984	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
663		985
664	This is an advanced topic that you do not normally need to use AnyEvent in	986	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	987	a module. This section is only of use to event loop authors who want to
666	provide AnyEvent compatibility.	988	provide AnyEvent compatibility.
…		…
722	model it chooses.	1044	model it chooses.
723		1045
724	=item C<PERL_ANYEVENT_MODEL>	1046	=item C<PERL_ANYEVENT_MODEL>
725		1047
726	This can be used to specify the event model to be used by AnyEvent, before	1048	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	1049	auto detection and -probing kicks in. It must be a string consisting
728	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1050	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,	1051	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	1052	used as event model. If it fails to load AnyEvent will proceed with
731	autodetection and -probing.	1053	auto detection and -probing.
732		1054
733	This functionality might change in future versions.	1055	This functionality might change in future versions.
734		1056
735	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1057	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
736	could start your program like this:	1058	could start your program like this:
737		1059
738	PERL_ANYEVENT_MODEL=Perl perl ...	1060	PERL_ANYEVENT_MODEL=Perl perl ...
		1061
		1062	=item C<PERL_ANYEVENT_PROTOCOLS>
		1063
		1064	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1065	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1066	of auto probing).
		1067
		1068	Must be set to a comma-separated list of protocols or address families,
		1069	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1070	used, and preference will be given to protocols mentioned earlier in the
		1071	list.
		1072
		1073	This variable can effectively be used for denial-of-service attacks
		1074	against local programs (e.g. when setuid), although the impact is likely
		1075	small, as the program has to handle connection errors already-
		1076
		1077	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1078	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1079	- only support IPv4, never try to resolve or contact IPv6
		1080	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1081	IPv6, but prefer IPv6 over IPv4.
		1082
		1083	=item C<PERL_ANYEVENT_EDNS0>
		1084
		1085	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1086	for DNS. This extension is generally useful to reduce DNS traffic, but
		1087	some (broken) firewalls drop such DNS packets, which is why it is off by
		1088	default.
		1089
		1090	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1091	EDNS0 in its DNS requests.
739		1092
740	=back	1093	=back
741		1094
742	=head1 EXAMPLE PROGRAM	1095	=head1 EXAMPLE PROGRAM
743		1096
…		…
754	poll => 'r',	1107	poll => 'r',
755	cb => sub {	1108	cb => sub {
756	warn "io event <$_[0]>\n"; # will always output <r>	1109	warn "io event <$_[0]>\n"; # will always output <r>
757	chomp (my $input = <STDIN>); # read a line	1110	chomp (my $input = <STDIN>); # read a line
758	warn "read: $input\n"; # output what has been read	1111	warn "read: $input\n"; # output what has been read
759	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1112	$cv->send if $input =~ /^q/i; # quit program if /^q/i
760	},	1113	},
761	);	1114	);
762		1115
763	my $time_watcher; # can only be used once	1116	my $time_watcher; # can only be used once
764		1117
…		…
769	});	1122	});
770	}	1123	}
771		1124
772	new_timer; # create first timer	1125	new_timer; # create first timer
773		1126
774	$cv->wait; # wait until user enters /^q/i	1127	$cv->recv; # wait until user enters /^q/i
775		1128
776	=head1 REAL-WORLD EXAMPLE	1129	=head1 REAL-WORLD EXAMPLE
777		1130
778	Consider the L<Net::FCP> module. It features (among others) the following	1131	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:	1132	API calls, which are to freenet what HTTP GET requests are to http:
…		…
829	syswrite $txn->{fh}, $txn->{request}	1182	syswrite $txn->{fh}, $txn->{request}
830	or die "connection or write error";	1183	or die "connection or write error";
831	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1184	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
832		1185
833	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1186	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:	1187	result and signals any possible waiters that the request has finished:
835		1188
836	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1189	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
837		1190
838	if (end-of-file or data complete) {	1191	if (end-of-file or data complete) {
839	$txn->{result} = $txn->{buf};	1192	$txn->{result} = $txn->{buf};
840	$txn->{finished}->broadcast;	1193	$txn->{finished}->send;
841	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1194	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
842	}	1195	}
843		1196
844	The C<result> method, finally, just waits for the finished signal (if the	1197	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	1198	request was already finished, it doesn't wait, of course, and returns the
846	data:	1199	data:
847		1200
848	$txn->{finished}->wait;	1201	$txn->{finished}->recv;
849	return $txn->{result};	1202	return $txn->{result};
850		1203
851	The actual code goes further and collects all errors (C<die>s, exceptions)	1204	The actual code goes further and collects all errors (C<die>s, exceptions)
852	that occured during request processing. The C<result> method detects	1205	that occurred during request processing. The C<result> method detects
853	whether an exception as thrown (it is stored inside the $txn object)	1206	whether an exception as thrown (it is stored inside the $txn object)
854	and just throws the exception, which means connection errors and other	1207	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	1208	problems get reported tot he code that tries to use the result, not in a
856	random callback.	1209	random callback.
857		1210
…		…
888		1241
889	my $quit = AnyEvent->condvar;	1242	my $quit = AnyEvent->condvar;
890		1243
891	$fcp->txn_client_get ($url)->cb (sub {	1244	$fcp->txn_client_get ($url)->cb (sub {
892	...	1245	...
893	$quit->broadcast;	1246	$quit->send;
894	});	1247	});
895		1248
896	$quit->wait;	1249	$quit->recv;
897		1250
898		1251
899	=head1 BENCHMARKS	1252	=head1 BENCHMARKS
900		1253
901	To give you an idea of the performance and overheads that AnyEvent adds	1254	To give you an idea of the performance and overheads that AnyEvent adds
…		…
903	of various event loops I prepared some benchmarks.	1256	of various event loops I prepared some benchmarks.
904		1257
905	=head2 BENCHMARKING ANYEVENT OVERHEAD	1258	=head2 BENCHMARKING ANYEVENT OVERHEAD
906		1259
907	Here is a benchmark of various supported event models used natively and	1260	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	1261	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,	1262	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.	1263	which it is), lets them fire exactly once and destroys them again.
911		1264
912	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1265	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
913	distribution.	1266	distribution.
…		…
930	all watchers, to avoid adding memory overhead. That means closure creation	1283	all watchers, to avoid adding memory overhead. That means closure creation
931	and memory usage is not included in the figures.	1284	and memory usage is not included in the figures.
932		1285
933	I<invoke> is the time, in microseconds, used to invoke a simple	1286	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	1287	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	1288	invoked "watcher" times, it would C<< ->send >> a condvar once to
936	signal the end of this phase.	1289	signal the end of this phase.
937		1290
938	I<destroy> is the time, in microseconds, that it takes to destroy a single	1291	I<destroy> is the time, in microseconds, that it takes to destroy a single
939	watcher.	1292	watcher.
940		1293
…		…
944	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1297	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	1298	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	1299	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	1300	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	1301	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	1302	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	1303	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	1304	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	1305	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	1306	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select
954		1307
…		…
958	well. For example, a select-based event loop (such as the pure perl one)	1311	well. For example, a select-based event loop (such as the pure perl one)
959	can never compete with an event loop that uses epoll when the number of	1312	can never compete with an event loop that uses epoll when the number of
960	file descriptors grows high. In this benchmark, all events become ready at	1313	file descriptors grows high. In this benchmark, all events become ready at
961	the same time, so select/poll-based implementations get an unnatural speed	1314	the same time, so select/poll-based implementations get an unnatural speed
962	boost.	1315	boost.
		1316
		1317	Also, note that the number of watchers usually has a nonlinear effect on
		1318	overall speed, that is, creating twice as many watchers doesn't take twice
		1319	the time - usually it takes longer. This puts event loops tested with a
		1320	higher number of watchers at a disadvantage.
		1321
		1322	To put the range of results into perspective, consider that on the
		1323	benchmark machine, handling an event takes roughly 1600 CPU cycles with
		1324	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
		1325	cycles with POE.
963		1326
964	C<EV> is the sole leader regarding speed and memory use, which are both	1327	C<EV> is the sole leader regarding speed and memory use, which are both
965	maximal/minimal, respectively. Even when going through AnyEvent, it uses	1328	maximal/minimal, respectively. Even when going through AnyEvent, it uses
966	far less memory than any other event loop and is still faster than Event	1329	far less memory than any other event loop and is still faster than Event
967	natively.	1330	natively.
…		…
990	file descriptor is dup()ed for each watcher. This shows that the dup()	1353	file descriptor is dup()ed for each watcher. This shows that the dup()
991	employed by some adaptors is not a big performance issue (it does incur a	1354	employed by some adaptors is not a big performance issue (it does incur a
992	hidden memory cost inside the kernel which is not reflected in the figures	1355	hidden memory cost inside the kernel which is not reflected in the figures
993	above).	1356	above).
994		1357
995	C<POE>, regardless of underlying event loop (whether using its pure	1358	C<POE>, regardless of underlying event loop (whether using its pure perl
996	perl select-based backend or the Event module, the POE-EV backend	1359	select-based backend or the Event module, the POE-EV backend couldn't
997	couldn't be tested because it wasn't working) shows abysmal performance	1360	be tested because it wasn't working) shows abysmal performance and
998	and memory usage: Watchers use almost 30 times as much memory as	1361	memory usage with AnyEvent: Watchers use almost 30 times as much memory
999	EV watchers, and 10 times as much memory as Event (the high memory	1362	as EV watchers, and 10 times as much memory as Event (the high memory
1000	requirements are caused by requiring a session for each watcher). Watcher	1363	requirements are caused by requiring a session for each watcher). Watcher
1001	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1364	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1365	implementation.
		1366
1002	implementation. The design of the POE adaptor class in AnyEvent can not	1367	The design of the POE adaptor class in AnyEvent can not really account
1003	really account for this, as session creation overhead is small compared	1368	for the performance issues, though, as session creation overhead is
1004	to execution of the state machine, which is coded pretty optimally within	1369	small compared to execution of the state machine, which is coded pretty
1005	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1370	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1371	using multiple sessions is not a good approach, especially regarding
		1372	memory usage, even the author of POE could not come up with a faster
		1373	design).
1006		1374
1007	=head3 Summary	1375	=head3 Summary
1008		1376
1009	=over 4	1377	=over 4
1010		1378
…		…
1021		1389
1022	=back	1390	=back
1023		1391
1024	=head2 BENCHMARKING THE LARGE SERVER CASE	1392	=head2 BENCHMARKING THE LARGE SERVER CASE
1025		1393
1026	This benchmark atcually benchmarks the event loop itself. It works by	1394	This benchmark actually benchmarks the event loop itself. It works by
1027	creating a number of "servers": each server consists of a socketpair, a	1395	creating a number of "servers": each server consists of a socket pair, a
1028	timeout watcher that gets reset on activity (but never fires), and an I/O	1396	timeout watcher that gets reset on activity (but never fires), and an I/O
1029	watcher waiting for input on one side of the socket. Each time the socket	1397	watcher waiting for input on one side of the socket. Each time the socket
1030	watcher reads a byte it will write that byte to a random other "server".	1398	watcher reads a byte it will write that byte to a random other "server".
1031		1399
1032	The effect is that there will be a lot of I/O watchers, only part of which	1400	The effect is that there will be a lot of I/O watchers, only part of which
1033	are active at any one point (so there is a constant number of active	1401	are active at any one point (so there is a constant number of active
1034	fds for each loop iterstaion, but which fds these are is random). The	1402	fds for each loop iteration, but which fds these are is random). The
1035	timeout is reset each time something is read because that reflects how	1403	timeout is reset each time something is read because that reflects how
1036	most timeouts work (and puts extra pressure on the event loops).	1404	most timeouts work (and puts extra pressure on the event loops).
1037		1405
1038	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1406	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1039	(1%) are active. This mirrors the activity of large servers with many	1407	(1%) are active. This mirrors the activity of large servers with many
1040	connections, most of which are idle at any one point in time.	1408	connections, most of which are idle at any one point in time.
1041		1409
1042	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1410	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1043	distribution.	1411	distribution.
…		…
1045	=head3 Explanation of the columns	1413	=head3 Explanation of the columns
1046		1414
1047	I<sockets> is the number of sockets, and twice the number of "servers" (as	1415	I<sockets> is the number of sockets, and twice the number of "servers" (as
1048	each server has a read and write socket end).	1416	each server has a read and write socket end).
1049		1417
1050	I<create> is the time it takes to create a socketpair (which is	1418	I<create> is the time it takes to create a socket pair (which is
1051	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1419	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1052		1420
1053	I<request>, the most important value, is the time it takes to handle a	1421	I<request>, the most important value, is the time it takes to handle a
1054	single "request", that is, reading the token from the pipe and forwarding	1422	single "request", that is, reading the token from the pipe and forwarding
1055	it to another server. This includes deleting the old timeout and creating	1423	it to another server. This includes deleting the old timeout and creating
…		…
1057		1425
1058	=head3 Results	1426	=head3 Results
1059		1427
1060	name sockets create request	1428	name sockets create request
1061	EV 20000 69.01 11.16	1429	EV 20000 69.01 11.16
1062	Perl 20000 75.28 112.76	1430	Perl 20000 73.32 35.87
1063	Event 20000 212.62 257.32	1431	Event 20000 212.62 257.32
1064	Glib 20000 651.16 1896.30	1432	Glib 20000 651.16 1896.30
1065	POE 20000 349.67 12317.24 uses POE::Loop::Event	1433	POE 20000 349.67 12317.24 uses POE::Loop::Event
1066		1434
1067	=head3 Discussion	1435	=head3 Discussion
…		…
1089		1457
1090	=head3 Summary	1458	=head3 Summary
1091		1459
1092	=over 4	1460	=over 4
1093		1461
1094	=item * The pure perl implementation performs extremely well, considering	1462	=item * The pure perl implementation performs extremely well.
1095	that it uses select.
1096		1463
1097	=item * Avoid Glib or POE in large projects where performance matters.	1464	=item * Avoid Glib or POE in large projects where performance matters.
1098		1465
1099	=back	1466	=back
1100		1467
…		…
1113		1480
1114	=head3 Results	1481	=head3 Results
1115		1482
1116	name sockets create request	1483	name sockets create request
1117	EV 16 20.00 6.54	1484	EV 16 20.00 6.54
		1485	Perl 16 25.75 12.62
1118	Event 16 81.27 35.86	1486	Event 16 81.27 35.86
1119	Glib 16 32.63 15.48	1487	Glib 16 32.63 15.48
1120	Perl 16 24.62 162.37
1121	POE 16 261.87 276.28 uses POE::Loop::Event	1488	POE 16 261.87 276.28 uses POE::Loop::Event
1122		1489
1123	=head3 Discussion	1490	=head3 Discussion
1124		1491
1125	The benchmark tries to test the performance of a typical small	1492	The benchmark tries to test the performance of a typical small
1126	server. While knowing how various event loops perform is interesting, keep	1493	server. While knowing how various event loops perform is interesting, keep
1127	in mind that their overhead in this case is usually not as important, due	1494	in mind that their overhead in this case is usually not as important, due
1128	to the small absolute number of watchers.	1495	to the small absolute number of watchers (that is, you need efficiency and
		1496	speed most when you have lots of watchers, not when you only have a few of
		1497	them).
1129		1498
1130	EV is again fastest.	1499	EV is again fastest.
1131		1500
1132	The C-based event loops Event and Glib come in second this time, as the	1501	Perl again comes second. It is noticeably faster than the C-based event
1133	overhead of running an iteration is much smaller in C than in Perl (little	1502	loops Event and Glib, although the difference is too small to really
1134	code to execute in the inner loop, and perl's function calling overhead is	1503	matter.
1135	high, and updating all the data structures is costly).
1136		1504
1137	The pure perl event loop is much slower, but still competitive.
1138
1139	POE also performs much better in this case, but is is stillf ar behind the	1505	POE also performs much better in this case, but is is still far behind the
1140	others.	1506	others.
1141		1507
1142	=head3 Summary	1508	=head3 Summary
1143		1509
1144	=over 4	1510	=over 4
…		…
1150		1516
1151		1517
1152	=head1 FORK	1518	=head1 FORK
1153		1519
1154	Most event libraries are not fork-safe. The ones who are usually are	1520	Most event libraries are not fork-safe. The ones who are usually are
1155	because they are so inefficient. Only L<EV> is fully fork-aware.	1521	because they rely on inefficient but fork-safe C<select> or C<poll>
		1522	calls. Only L<EV> is fully fork-aware.
1156		1523
1157	If you have to fork, you must either do so I<before> creating your first	1524	If you have to fork, you must either do so I<before> creating your first
1158	watcher OR you must not use AnyEvent at all in the child.	1525	watcher OR you must not use AnyEvent at all in the child.
1159		1526
1160		1527
…		…
1172		1539
1173	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1540	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1174		1541
1175	use AnyEvent;	1542	use AnyEvent;
1176		1543
		1544	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1545	be used to probe what backend is used and gain other information (which is
		1546	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
		1547
1177		1548
1178	=head1 SEE ALSO	1549	=head1 SEE ALSO
1179		1550
1180	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1551	Utility functions: L<AnyEvent::Util>.
1181	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1552
		1553	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1182	L<Event::Lib>, L<Qt>, L<POE>.	1554	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1183		1555
1184	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1556	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1185	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1557	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1186	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1558	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1187	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1559	L<AnyEvent::Impl::POE>.
1188		1560
		1561	Non-blocking file handles, sockets, TCP clients and
		1562	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1563
		1564	Asynchronous DNS: L<AnyEvent::DNS>.
		1565
		1566	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1567
1189	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1568	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1190		1569
1191		1570
1192	=head1 AUTHOR	1571	=head1 AUTHOR
1193		1572
1194	Marc Lehmann <schmorp@schmorp.de>	1573	Marc Lehmann <schmorp@schmorp.de>

Diff Legend

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

Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.94 by root, Sat Apr 26 04:33:51 2008 UTC vs. Revision 1.131 by root, Sat May 24 17:48:38 2008 UTC

Diff Legend

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.94 by root, Sat Apr 26 04:33:51 2008 UTC vs.
Revision 1.131 by root, Sat May 24 17:48:38 2008 UTC