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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.100 by elmex, Sun Apr 27 19:15:43 2008 UTC vs.
Revision 1.135 by root, Sun May 25 04:49:01 2008 UTC

…		…
1	=head1 NAME	1	=head1 => NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
16	...	16	...
17	});	17	});
18		18
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	19	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		20	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	21	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's
22		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	#TODO#
72
73	Net::IRC3
74	AnyEvent::HTTPD
75	AnyEvent::DNS
76	IO::AnyEvent
77	Net::FPing
78	Net::XMPP2
79	Coro
80
81	AnyEvent::IRC
82	AnyEvent::HTTPD
83	AnyEvent::DNS
84	AnyEvent::Handle
85	AnyEvent::Socket
86	AnyEvent::FPing
87	AnyEvent::XMPP
88	AnyEvent::SNMP
89	Coro
90		70
91	=head1 DESCRIPTION	71	=head1 DESCRIPTION
92		72
93	L<AnyEvent> provides an identical interface to multiple event loops. This	73	L<AnyEvent> provides an identical interface to multiple event loops. This
94	allows module authors to utilise an event loop without forcing module	74	allows module authors to utilise an event loop without forcing module
…		…
98	The interface itself is vaguely similar, but not identical to the L<Event>	78	The interface itself is vaguely similar, but not identical to the L<Event>
99	module.	79	module.
100		80
101	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
102	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
103	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	83	following modules is already loaded: L<EV>,
104	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>,
105	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
106	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
107	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
108	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
…		…
128		108
129	=head1 WATCHERS	109	=head1 WATCHERS
130		110
131	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
132	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
133	the callback to call, the filehandle to watch, etc.	113	the callback to call, the file handle to watch, etc.
134		114
135	These watchers are normal Perl objects with normal Perl lifetime. After	115	These watchers are normal Perl objects with normal Perl lifetime. After
136	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
137	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
138	is in control).	118	is in control).
…		…
257		237
258	Although the callback might get passed parameters, their value and	238	Although the callback might get passed parameters, their value and
259	presence is undefined and you cannot rely on them. Portable AnyEvent	239	presence is undefined and you cannot rely on them. Portable AnyEvent
260	callbacks cannot use arguments passed to signal watcher callbacks.	240	callbacks cannot use arguments passed to signal watcher callbacks.
261		241
262	Multiple signal occurances can be clumped together into one callback	242	Multiple signal occurrences can be clumped together into one callback
263	invocation, and callback invocation will be synchronous. synchronous means	243	invocation, and callback invocation will be synchronous. Synchronous means
264	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,
265	but it is guarenteed not to interrupt any other callbacks.	245	but it is guaranteed not to interrupt any other callbacks.
266		246
267	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
268	between multiple watchers.	248	between multiple watchers.
269		249
270	This watcher might use C<%SIG>, so programs overwriting those signals	250	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
299		279
300	Example: fork a process and wait for it	280	Example: fork a process and wait for it
301		281
302	my $done = AnyEvent->condvar;	282	my $done = AnyEvent->condvar;
303		283
304	AnyEvent::detect; # force event module to be initialised
305
306	my $pid = fork or exit 5;	284	my $pid = fork or exit 5;
307		285
308	my $w = AnyEvent->child (	286	my $w = AnyEvent->child (
309	pid => $pid,	287	pid => $pid,
310	cb => sub {	288	cb => sub {
311	my ($pid, $status) = @_;	289	my ($pid, $status) = @_;
312	warn "pid $pid exited with status $status";	290	warn "pid $pid exited with status $status";
313	$done->broadcast;	291	$done->send;
314	},	292	},
315	);	293	);
316		294
317	# do something else, then wait for process exit	295	# do something else, then wait for process exit
318	$done->wait;	296	$done->recv;
319		297
320	=head2 CONDITION VARIABLES	298	=head2 CONDITION VARIABLES
321		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
322	Condition variables can be created by calling the C<< AnyEvent->condvar >>	310	Condition variables can be created by calling the C<< AnyEvent->condvar
323	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.
324		314
325	A condition variable waits for a condition - precisely that the C<<	315	After creation, the condition variable is "false" until it becomes "true"
326	->broadcast >> method has been called.	316	by calling the C<send> method (or calling the condition variable as if it
		317	were a callback, read about the caveats in the description for the C<<
		318	->send >> method).
327		319
328	They are very useful to signal that a condition has been fulfilled, for	320	Condition variables are similar to callbacks, except that you can
		321	optionally wait for them. They can also be called merge points - points
		322	in time where multiple outstanding events have been processed. And yet
		323	another way to call them is transactions - each condition variable can be
		324	used to represent a transaction, which finishes at some point and delivers
		325	a result.
		326
		327	Condition variables are very useful to signal that something has finished,
329	example, if you write a module that does asynchronous http requests,	328	for example, if you write a module that does asynchronous http requests,
330	then a condition variable would be the ideal candidate to signal the	329	then a condition variable would be the ideal candidate to signal the
331	availability of results.	330	availability of results. The user can either act when the callback is
		331	called or can synchronously C<< ->recv >> for the results.
332		332
333	You can also use condition variables to block your main program until	333	You can also use them to simulate traditional event loops - for example,
334	an event occurs - for example, you could C<< ->wait >> in your main	334	you can block your main program until an event occurs - for example, you
335	program until the user clicks the Quit button in your app, which would C<<	335	could C<< ->recv >> in your main program until the user clicks the Quit
336	->broadcast >> the "quit" event.	336	button of your app, which would C<< ->send >> the "quit" event.
337		337
338	Note that condition variables recurse into the event loop - if you have	338	Note that condition variables recurse into the event loop - if you have
339	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you	339	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
340	lose. Therefore, condition variables are good to export to your caller, but	340	lose. Therefore, condition variables are good to export to your caller, but
341	you should avoid making a blocking wait yourself, at least in callbacks,	341	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	342	as this asks for trouble.
343		343
344	This object has two methods:	344	Condition variables are represented by hash refs in perl, and the keys
		345	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		346	easy (it is often useful to build your own transaction class on top of
		347	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		348	it's C<new> method in your own C<new> method.
		349
		350	There are two "sides" to a condition variable - the "producer side" which
		351	eventually calls C<< -> send >>, and the "consumer side", which waits
		352	for the send to occur.
		353
		354	Example: wait for a timer.
		355
		356	# wait till the result is ready
		357	my $result_ready = AnyEvent->condvar;
		358
		359	# do something such as adding a timer
		360	# or socket watcher the calls $result_ready->send
		361	# when the "result" is ready.
		362	# in this case, we simply use a timer:
		363	my $w = AnyEvent->timer (
		364	after => 1,
		365	cb => sub { $result_ready->send },
		366	);
		367
		368	# this "blocks" (while handling events) till the callback
		369	# calls send
		370	$result_ready->recv;
		371
		372	Example: wait for a timer, but take advantage of the fact that
		373	condition variables are also code references.
		374
		375	my $done = AnyEvent->condvar;
		376	my $delay = AnyEvent->timer (after => 5, cb => $done);
		377	$done->recv;
		378
		379	=head3 METHODS FOR PRODUCERS
		380
		381	These methods should only be used by the producing side, i.e. the
		382	code/module that eventually sends the signal. Note that it is also
		383	the producer side which creates the condvar in most cases, but it isn't
		384	uncommon for the consumer to create it as well.
345		385
346	=over 4	386	=over 4
347		387
		388	=item $cv->send (...)
		389
		390	Flag the condition as ready - a running C<< ->recv >> and all further
		391	calls to C<recv> will (eventually) return after this method has been
		392	called. If nobody is waiting the send will be remembered.
		393
		394	If a callback has been set on the condition variable, it is called
		395	immediately from within send.
		396
		397	Any arguments passed to the C<send> call will be returned by all
		398	future C<< ->recv >> calls.
		399
		400	Condition variables are overloaded so one can call them directly
		401	(as a code reference). Calling them directly is the same as calling
		402	C<send>. Note, however, that many C-based event loops do not handle
		403	overloading, so as tempting as it may be, passing a condition variable
		404	instead of a callback does not work. Both the pure perl and EV loops
		405	support overloading, however, as well as all functions that use perl to
		406	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		407	example).
		408
		409	=item $cv->croak ($error)
		410
		411	Similar to send, but causes all call's to C<< ->recv >> to invoke
		412	C<Carp::croak> with the given error message/object/scalar.
		413
		414	This can be used to signal any errors to the condition variable
		415	user/consumer.
		416
		417	=item $cv->begin ([group callback])
		418
348	=item $cv->wait	419	=item $cv->end
349		420
350	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	421	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		422
		423	These two methods can be used to combine many transactions/events into
		424	one. For example, a function that pings many hosts in parallel might want
		425	to use a condition variable for the whole process.
		426
		427	Every call to C<< ->begin >> will increment a counter, and every call to
		428	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		429	>>, the (last) callback passed to C<begin> will be executed. That callback
		430	is I<supposed> to call C<< ->send >>, but that is not required. If no
		431	callback was set, C<send> will be called without any arguments.
		432
		433	Let's clarify this with the ping example:
		434
		435	my $cv = AnyEvent->condvar;
		436
		437	my %result;
		438	$cv->begin (sub { $cv->send (\%result) });
		439
		440	for my $host (@list_of_hosts) {
		441	$cv->begin;
		442	ping_host_then_call_callback $host, sub {
		443	$result{$host} = ...;
		444	$cv->end;
		445	};
		446	}
		447
		448	$cv->end;
		449
		450	This code fragment supposedly pings a number of hosts and calls
		451	C<send> after results for all then have have been gathered - in any
		452	order. To achieve this, the code issues a call to C<begin> when it starts
		453	each ping request and calls C<end> when it has received some result for
		454	it. Since C<begin> and C<end> only maintain a counter, the order in which
		455	results arrive is not relevant.
		456
		457	There is an additional bracketing call to C<begin> and C<end> outside the
		458	loop, which serves two important purposes: first, it sets the callback
		459	to be called once the counter reaches C<0>, and second, it ensures that
		460	C<send> is called even when C<no> hosts are being pinged (the loop
		461	doesn't execute once).
		462
		463	This is the general pattern when you "fan out" into multiple subrequests:
		464	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		465	is called at least once, and then, for each subrequest you start, call
		466	C<begin> and for each subrequest you finish, call C<end>.
		467
		468	=back
		469
		470	=head3 METHODS FOR CONSUMERS
		471
		472	These methods should only be used by the consuming side, i.e. the
		473	code awaits the condition.
		474
		475	=over 4
		476
		477	=item $cv->recv
		478
		479	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
351	called on c<$cv>, while servicing other watchers normally.	480	>> methods have been called on c<$cv>, while servicing other watchers
		481	normally.
352		482
353	You can only wait once on a condition - additional calls will return	483	You can only wait once on a condition - additional calls are valid but
354	immediately.	484	will return immediately.
		485
		486	If an error condition has been set by calling C<< ->croak >>, then this
		487	function will call C<croak>.
		488
		489	In list context, all parameters passed to C<send> will be returned,
		490	in scalar context only the first one will be returned.
355		491
356	Not all event models support a blocking wait - some die in that case	492	Not all event models support a blocking wait - some die in that case
357	(programs might want to do that to stay interactive), so I<if you are	493	(programs might want to do that to stay interactive), so I<if you are
358	using this from a module, never require a blocking wait>, but let the	494	using this from a module, never require a blocking wait>, but let the
359	caller decide whether the call will block or not (for example, by coupling	495	caller decide whether the call will block or not (for example, by coupling
360	condition variables with some kind of request results and supporting	496	condition variables with some kind of request results and supporting
361	callbacks so the caller knows that getting the result will not block,	497	callbacks so the caller knows that getting the result will not block,
362	while still suppporting blocking waits if the caller so desires).	498	while still supporting blocking waits if the caller so desires).
363		499
364	Another reason I<never> to C<< ->wait >> in a module is that you cannot	500	Another reason I<never> to C<< ->recv >> in a module is that you cannot
365	sensibly have two C<< ->wait >>'s in parallel, as that would require	501	sensibly have two C<< ->recv >>'s in parallel, as that would require
366	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	502	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
367	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	503	can supply.
368	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
369	from different coroutines, however).
370		504
371	=item $cv->broadcast	505	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		506	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		507	versions and also integrates coroutines into AnyEvent, making blocking
		508	C<< ->recv >> calls perfectly safe as long as they are done from another
		509	coroutine (one that doesn't run the event loop).
372		510
373	Flag the condition as ready - a running C<< ->wait >> and all further	511	You can ensure that C<< -recv >> never blocks by setting a callback and
374	calls to C<wait> will (eventually) return after this method has been	512	only calling C<< ->recv >> from within that callback (or at a later
375	called. If nobody is waiting the broadcast will be remembered..	513	time). This will work even when the event loop does not support blocking
		514	waits otherwise.
		515
		516	=item $bool = $cv->ready
		517
		518	Returns true when the condition is "true", i.e. whether C<send> or
		519	C<croak> have been called.
		520
		521	=item $cb = $cv->cb ([new callback])
		522
		523	This is a mutator function that returns the callback set and optionally
		524	replaces it before doing so.
		525
		526	The callback will be called when the condition becomes "true", i.e. when
		527	C<send> or C<croak> are called. Calling C<recv> inside the callback
		528	or at any later time is guaranteed not to block.
376		529
377	=back	530	=back
378
379	Example:
380
381	# wait till the result is ready
382	my $result_ready = AnyEvent->condvar;
383
384	# do something such as adding a timer
385	# or socket watcher the calls $result_ready->broadcast
386	# when the "result" is ready.
387	# in this case, we simply use a timer:
388	my $w = AnyEvent->timer (
389	after => 1,
390	cb => sub { $result_ready->broadcast },
391	);
392
393	# this "blocks" (while handling events) till the watcher
394	# calls broadcast
395	$result_ready->wait;
396		531
397	=head1 GLOBAL VARIABLES AND FUNCTIONS	532	=head1 GLOBAL VARIABLES AND FUNCTIONS
398		533
399	=over 4	534	=over 4
400		535
…		…
406	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	541	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
407	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	542	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
408		543
409	The known classes so far are:	544	The known classes so far are:
410		545
411	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
412	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
413	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	546	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
414	AnyEvent::Impl::Event based on Event, second best choice.	547	AnyEvent::Impl::Event based on Event, second best choice.
		548	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
415	AnyEvent::Impl::Glib based on Glib, third-best choice.	549	AnyEvent::Impl::Glib based on Glib, third-best choice.
416	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
417	AnyEvent::Impl::Tk based on Tk, very bad choice.	550	AnyEvent::Impl::Tk based on Tk, very bad choice.
418	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	551	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
419	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	552	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
420	AnyEvent::Impl::POE based on POE, not generic enough for full support.	553	AnyEvent::Impl::POE based on POE, not generic enough for full support.
421		554
…		…
434	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	567	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
435	if necessary. You should only call this function right before you would	568	if necessary. You should only call this function right before you would
436	have created an AnyEvent watcher anyway, that is, as late as possible at	569	have created an AnyEvent watcher anyway, that is, as late as possible at
437	runtime.	570	runtime.
438		571
		572	=item $guard = AnyEvent::post_detect { BLOCK }
		573
		574	Arranges for the code block to be executed as soon as the event model is
		575	autodetected (or immediately if this has already happened).
		576
		577	If called in scalar or list context, then it creates and returns an object
		578	that automatically removes the callback again when it is destroyed. See
		579	L<Coro::BDB> for a case where this is useful.
		580
		581	=item @AnyEvent::post_detect
		582
		583	If there are any code references in this array (you can C<push> to it
		584	before or after loading AnyEvent), then they will called directly after
		585	the event loop has been chosen.
		586
		587	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		588	if it contains a true value then the event loop has already been detected,
		589	and the array will be ignored.
		590
		591	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		592
439	=back	593	=back
440		594
441	=head1 WHAT TO DO IN A MODULE	595	=head1 WHAT TO DO IN A MODULE
442		596
443	As a module author, you should C<use AnyEvent> and call AnyEvent methods	597	As a module author, you should C<use AnyEvent> and call AnyEvent methods
…		…
446	Be careful when you create watchers in the module body - AnyEvent will	600	Be careful when you create watchers in the module body - AnyEvent will
447	decide which event module to use as soon as the first method is called, so	601	decide which event module to use as soon as the first method is called, so
448	by calling AnyEvent in your module body you force the user of your module	602	by calling AnyEvent in your module body you force the user of your module
449	to load the event module first.	603	to load the event module first.
450		604
451	Never call C<< ->wait >> on a condition variable unless you I<know> that	605	Never call C<< ->recv >> on a condition variable unless you I<know> that
452	the C<< ->broadcast >> method has been called on it already. This is	606	the C<< ->send >> method has been called on it already. This is
453	because it will stall the whole program, and the whole point of using	607	because it will stall the whole program, and the whole point of using
454	events is to stay interactive.	608	events is to stay interactive.
455		609
456	It is fine, however, to call C<< ->wait >> when the user of your module	610	It is fine, however, to call C<< ->recv >> when the user of your module
457	requests it (i.e. if you create a http request object ad have a method	611	requests it (i.e. if you create a http request object ad have a method
458	called C<results> that returns the results, it should call C<< ->wait >>	612	called C<results> that returns the results, it should call C<< ->recv >>
459	freely, as the user of your module knows what she is doing. always).	613	freely, as the user of your module knows what she is doing. always).
460		614
461	=head1 WHAT TO DO IN THE MAIN PROGRAM	615	=head1 WHAT TO DO IN THE MAIN PROGRAM
462		616
463	There will always be a single main program - the only place that should	617	There will always be a single main program - the only place that should
…		…
465		619
466	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	620	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
467	do anything special (it does not need to be event-based) and let AnyEvent	621	do anything special (it does not need to be event-based) and let AnyEvent
468	decide which implementation to chose if some module relies on it.	622	decide which implementation to chose if some module relies on it.
469		623
470	If the main program relies on a specific event model. For example, in	624	If the main program relies on a specific event model - for example, in
471	Gtk2 programs you have to rely on the Glib module. You should load the	625	Gtk2 programs you have to rely on the Glib module - you should load the
472	event module before loading AnyEvent or any module that uses it: generally	626	event module before loading AnyEvent or any module that uses it: generally
473	speaking, you should load it as early as possible. The reason is that	627	speaking, you should load it as early as possible. The reason is that
474	modules might create watchers when they are loaded, and AnyEvent will	628	modules might create watchers when they are loaded, and AnyEvent will
475	decide on the event model to use as soon as it creates watchers, and it	629	decide on the event model to use as soon as it creates watchers, and it
476	might chose the wrong one unless you load the correct one yourself.	630	might chose the wrong one unless you load the correct one yourself.
477		631
478	You can chose to use a rather inefficient pure-perl implementation by	632	You can chose to use a pure-perl implementation by loading the
479	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	633	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
480	behaviour everywhere, but letting AnyEvent chose is generally better.	634	everywhere, but letting AnyEvent chose the model is generally better.
		635
		636	=head2 MAINLOOP EMULATION
		637
		638	Sometimes (often for short test scripts, or even standalone programs who
		639	only want to use AnyEvent), you do not want to run a specific event loop.
		640
		641	In that case, you can use a condition variable like this:
		642
		643	AnyEvent->condvar->recv;
		644
		645	This has the effect of entering the event loop and looping forever.
		646
		647	Note that usually your program has some exit condition, in which case
		648	it is better to use the "traditional" approach of storing a condition
		649	variable somewhere, waiting for it, and sending it when the program should
		650	exit cleanly.
		651
481		652
482	=head1 OTHER MODULES	653	=head1 OTHER MODULES
483		654
484	L<AnyEvent> itself comes with useful utility modules:	655	The following is a non-exhaustive list of additional modules that use
485		656	AnyEvent and can therefore be mixed easily with other AnyEvent modules
486	To make it easier to do non-blocking IO the modules L<AnyEvent::Handle>	657	in the same program. Some of the modules come with AnyEvent, some are
487	and L<AnyEvent::Socket> are provided. L<AnyEvent::Handle> provides	658	available via CPAN.
488	read and write buffers and manages watchers for reads and writes.
489	L<AnyEvent::Socket> provides means to do non-blocking connects.
490
491	Aside from those there are these modules that support AnyEvent (and use it
492	for non-blocking IO):
493		659
494	=over 4	660	=over 4
495		661
		662	=item L<AnyEvent::Util>
		663
		664	Contains various utility functions that replace often-used but blocking
		665	functions such as C<inet_aton> by event-/callback-based versions.
		666
		667	=item L<AnyEvent::Handle>
		668
		669	Provide read and write buffers and manages watchers for reads and writes.
		670
		671	=item L<AnyEvent::Socket>
		672
		673	Provides various utility functions for (internet protocol) sockets,
		674	addresses and name resolution. Also functions to create non-blocking tcp
		675	connections or tcp servers, with IPv6 and SRV record support and more.
		676
		677	=item L<AnyEvent::DNS>
		678
		679	Provides rich asynchronous DNS resolver capabilities.
		680
		681	=item L<AnyEvent::HTTPD>
		682
		683	Provides a simple web application server framework.
		684
496	=item L<AnyEvent::FastPing>	685	=item L<AnyEvent::FastPing>
497		686
		687	The fastest ping in the west.
		688
498	=item L<Net::IRC3>	689	=item L<Net::IRC3>
499		690
		691	AnyEvent based IRC client module family.
		692
500	=item L<Net::XMPP2>	693	=item L<Net::XMPP2>
		694
		695	AnyEvent based XMPP (Jabber protocol) module family.
		696
		697	=item L<Net::FCP>
		698
		699	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		700	of AnyEvent.
		701
		702	=item L<Event::ExecFlow>
		703
		704	High level API for event-based execution flow control.
		705
		706	=item L<Coro>
		707
		708	Has special support for AnyEvent via L<Coro::AnyEvent>.
		709
		710	=item L<AnyEvent::AIO>, L<IO::AIO>
		711
		712	Truly asynchronous I/O, should be in the toolbox of every event
		713	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
		714	together.
		715
		716	=item L<AnyEvent::BDB>, L<BDB>
		717
		718	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
		719	IO::AIO and AnyEvent together.
		720
		721	=item L<IO::Lambda>
		722
		723	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
501		724
502	=back	725	=back
503		726
504	=cut	727	=cut
505		728
…		…
508	no warnings;	731	no warnings;
509	use strict;	732	use strict;
510		733
511	use Carp;	734	use Carp;
512		735
513	our $VERSION = '3.3';	736	our $VERSION = '4.03';
514	our $MODEL;	737	our $MODEL;
515		738
516	our $AUTOLOAD;	739	our $AUTOLOAD;
517	our @ISA;	740	our @ISA;
518		741
		742	our @REGISTRY;
		743
519	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	744	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
520		745
521	our @REGISTRY;	746	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2)
		747
		748	{
		749	my $idx;
		750	$PROTOCOL{$_} = ++$idx
		751	for split /\s,\s/, $ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		752	}
522		753
523	my @models = (	754	my @models = (
524	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
525	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
526	[EV:: => AnyEvent::Impl::EV::],	755	[EV:: => AnyEvent::Impl::EV::],
527	[Event:: => AnyEvent::Impl::Event::],	756	[Event:: => AnyEvent::Impl::Event::],
528	[Glib:: => AnyEvent::Impl::Glib::],
529	[Tk:: => AnyEvent::Impl::Tk::],
530	[Wx:: => AnyEvent::Impl::POE::],
531	[Prima:: => AnyEvent::Impl::POE::],
532	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	757	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
533	# everything below here will not be autoprobed as the pureperl backend should work everywhere	758	# everything below here will not be autoprobed
		759	# as the pureperl backend should work everywhere
		760	# and is usually faster
		761	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		762	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
534	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	763	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
535	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	764	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
536	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	765	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		766	[Wx:: => AnyEvent::Impl::POE::],
		767	[Prima:: => AnyEvent::Impl::POE::],
537	);	768	);
538		769
539	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	770	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
		771
		772	our @post_detect;
		773
		774	sub post_detect(&) {
		775	my ($cb) = @_;
		776
		777	if ($MODEL) {
		778	$cb->();
		779
		780	1
		781	} else {
		782	push @post_detect, $cb;
		783
		784	defined wantarray
		785	? bless \$cb, "AnyEvent::Util::PostDetect"
		786	: ()
		787	}
		788	}
		789
		790	sub AnyEvent::Util::PostDetect::DESTROY {
		791	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		792	}
540		793
541	sub detect() {	794	sub detect() {
542	unless ($MODEL) {	795	unless ($MODEL) {
543	no strict 'refs';	796	no strict 'refs';
544		797
…		…
578	last;	831	last;
579	}	832	}
580	}	833	}
581		834
582	$MODEL	835	$MODEL
583	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	836	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
584	}	837	}
585	}	838	}
586		839
587	unshift @ISA, $MODEL;	840	unshift @ISA, $MODEL;
588	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	841	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		842
		843	(shift @post_detect)->() while @post_detect;
589	}	844	}
590		845
591	$MODEL	846	$MODEL
592	}	847	}
593		848
…		…
603	$class->$func (@_);	858	$class->$func (@_);
604	}	859	}
605		860
606	package AnyEvent::Base;	861	package AnyEvent::Base;
607		862
608	# default implementation for ->condvar, ->wait, ->broadcast	863	# default implementation for ->condvar
609		864
610	sub condvar {	865	sub condvar {
611	bless \my $flag, "AnyEvent::Base::CondVar"	866	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
612	}
613
614	sub AnyEvent::Base::CondVar::broadcast {
615	${$_[0]}++;
616	}
617
618	sub AnyEvent::Base::CondVar::wait {
619	AnyEvent->one_event while !${$_[0]};
620	}	867	}
621		868
622	# default implementation for ->signal	869	# default implementation for ->signal
623		870
624	our %SIG_CB;	871	our %SIG_CB;
…		…
698	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	945	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
699		946
700	undef $CHLD_W unless keys %PID_CB;	947	undef $CHLD_W unless keys %PID_CB;
701	}	948	}
702		949
		950	package AnyEvent::CondVar;
		951
		952	our @ISA = AnyEvent::CondVar::Base::;
		953
		954	package AnyEvent::CondVar::Base;
		955
		956	use overload
		957	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		958	fallback => 1;
		959
		960	sub _send {
		961	# nop
		962	}
		963
		964	sub send {
		965	my $cv = shift;
		966	$cv->{_ae_sent} = [@_];
		967	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		968	$cv->_send;
		969	}
		970
		971	sub croak {
		972	$_[0]{_ae_croak} = $_[1];
		973	$_[0]->send;
		974	}
		975
		976	sub ready {
		977	$_[0]{_ae_sent}
		978	}
		979
		980	sub _wait {
		981	AnyEvent->one_event while !$_[0]{_ae_sent};
		982	}
		983
		984	sub recv {
		985	$_[0]->_wait;
		986
		987	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		988	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		989	}
		990
		991	sub cb {
		992	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		993	$_[0]{_ae_cb}
		994	}
		995
		996	sub begin {
		997	++$_[0]{_ae_counter};
		998	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		999	}
		1000
		1001	sub end {
		1002	return if --$_[0]{_ae_counter};
		1003	&{ $_[0]{_ae_end_cb} \|\| sub { $_[0]->send } };
		1004	}
		1005
		1006	# undocumented/compatibility with pre-3.4
		1007	*broadcast = \&send;
		1008	*wait = \&_wait;
		1009
703	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1010	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
704		1011
705	This is an advanced topic that you do not normally need to use AnyEvent in	1012	This is an advanced topic that you do not normally need to use AnyEvent in
706	a module. This section is only of use to event loop authors who want to	1013	a module. This section is only of use to event loop authors who want to
707	provide AnyEvent compatibility.	1014	provide AnyEvent compatibility.
…		…
763	model it chooses.	1070	model it chooses.
764		1071
765	=item C<PERL_ANYEVENT_MODEL>	1072	=item C<PERL_ANYEVENT_MODEL>
766		1073
767	This can be used to specify the event model to be used by AnyEvent, before	1074	This can be used to specify the event model to be used by AnyEvent, before
768	autodetection and -probing kicks in. It must be a string consisting	1075	auto detection and -probing kicks in. It must be a string consisting
769	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1076	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
770	and the resulting module name is loaded and if the load was successful,	1077	and the resulting module name is loaded and if the load was successful,
771	used as event model. If it fails to load AnyEvent will proceed with	1078	used as event model. If it fails to load AnyEvent will proceed with
772	autodetection and -probing.	1079	auto detection and -probing.
773		1080
774	This functionality might change in future versions.	1081	This functionality might change in future versions.
775		1082
776	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1083	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
777	could start your program like this:	1084	could start your program like this:
778		1085
779	PERL_ANYEVENT_MODEL=Perl perl ...	1086	PERL_ANYEVENT_MODEL=Perl perl ...
		1087
		1088	=item C<PERL_ANYEVENT_PROTOCOLS>
		1089
		1090	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1091	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1092	of auto probing).
		1093
		1094	Must be set to a comma-separated list of protocols or address families,
		1095	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1096	used, and preference will be given to protocols mentioned earlier in the
		1097	list.
		1098
		1099	This variable can effectively be used for denial-of-service attacks
		1100	against local programs (e.g. when setuid), although the impact is likely
		1101	small, as the program has to handle connection errors already-
		1102
		1103	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1104	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1105	- only support IPv4, never try to resolve or contact IPv6
		1106	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1107	IPv6, but prefer IPv6 over IPv4.
		1108
		1109	=item C<PERL_ANYEVENT_EDNS0>
		1110
		1111	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1112	for DNS. This extension is generally useful to reduce DNS traffic, but
		1113	some (broken) firewalls drop such DNS packets, which is why it is off by
		1114	default.
		1115
		1116	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1117	EDNS0 in its DNS requests.
780		1118
781	=back	1119	=back
782		1120
783	=head1 EXAMPLE PROGRAM	1121	=head1 EXAMPLE PROGRAM
784		1122
…		…
795	poll => 'r',	1133	poll => 'r',
796	cb => sub {	1134	cb => sub {
797	warn "io event <$_[0]>\n"; # will always output <r>	1135	warn "io event <$_[0]>\n"; # will always output <r>
798	chomp (my $input = <STDIN>); # read a line	1136	chomp (my $input = <STDIN>); # read a line
799	warn "read: $input\n"; # output what has been read	1137	warn "read: $input\n"; # output what has been read
800	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1138	$cv->send if $input =~ /^q/i; # quit program if /^q/i
801	},	1139	},
802	);	1140	);
803		1141
804	my $time_watcher; # can only be used once	1142	my $time_watcher; # can only be used once
805		1143
…		…
810	});	1148	});
811	}	1149	}
812		1150
813	new_timer; # create first timer	1151	new_timer; # create first timer
814		1152
815	$cv->wait; # wait until user enters /^q/i	1153	$cv->recv; # wait until user enters /^q/i
816		1154
817	=head1 REAL-WORLD EXAMPLE	1155	=head1 REAL-WORLD EXAMPLE
818		1156
819	Consider the L<Net::FCP> module. It features (among others) the following	1157	Consider the L<Net::FCP> module. It features (among others) the following
820	API calls, which are to freenet what HTTP GET requests are to http:	1158	API calls, which are to freenet what HTTP GET requests are to http:
…		…
870	syswrite $txn->{fh}, $txn->{request}	1208	syswrite $txn->{fh}, $txn->{request}
871	or die "connection or write error";	1209	or die "connection or write error";
872	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1210	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
873		1211
874	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1212	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
875	result and signals any possible waiters that the request ahs finished:	1213	result and signals any possible waiters that the request has finished:
876		1214
877	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1215	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
878		1216
879	if (end-of-file or data complete) {	1217	if (end-of-file or data complete) {
880	$txn->{result} = $txn->{buf};	1218	$txn->{result} = $txn->{buf};
881	$txn->{finished}->broadcast;	1219	$txn->{finished}->send;
882	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1220	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
883	}	1221	}
884		1222
885	The C<result> method, finally, just waits for the finished signal (if the	1223	The C<result> method, finally, just waits for the finished signal (if the
886	request was already finished, it doesn't wait, of course, and returns the	1224	request was already finished, it doesn't wait, of course, and returns the
887	data:	1225	data:
888		1226
889	$txn->{finished}->wait;	1227	$txn->{finished}->recv;
890	return $txn->{result};	1228	return $txn->{result};
891		1229
892	The actual code goes further and collects all errors (C<die>s, exceptions)	1230	The actual code goes further and collects all errors (C<die>s, exceptions)
893	that occured during request processing. The C<result> method detects	1231	that occurred during request processing. The C<result> method detects
894	whether an exception as thrown (it is stored inside the $txn object)	1232	whether an exception as thrown (it is stored inside the $txn object)
895	and just throws the exception, which means connection errors and other	1233	and just throws the exception, which means connection errors and other
896	problems get reported tot he code that tries to use the result, not in a	1234	problems get reported tot he code that tries to use the result, not in a
897	random callback.	1235	random callback.
898		1236
…		…
929		1267
930	my $quit = AnyEvent->condvar;	1268	my $quit = AnyEvent->condvar;
931		1269
932	$fcp->txn_client_get ($url)->cb (sub {	1270	$fcp->txn_client_get ($url)->cb (sub {
933	...	1271	...
934	$quit->broadcast;	1272	$quit->send;
935	});	1273	});
936		1274
937	$quit->wait;	1275	$quit->recv;
938		1276
939		1277
940	=head1 BENCHMARKS	1278	=head1 BENCHMARKS
941		1279
942	To give you an idea of the performance and overheads that AnyEvent adds	1280	To give you an idea of the performance and overheads that AnyEvent adds
…		…
944	of various event loops I prepared some benchmarks.	1282	of various event loops I prepared some benchmarks.
945		1283
946	=head2 BENCHMARKING ANYEVENT OVERHEAD	1284	=head2 BENCHMARKING ANYEVENT OVERHEAD
947		1285
948	Here is a benchmark of various supported event models used natively and	1286	Here is a benchmark of various supported event models used natively and
949	through anyevent. The benchmark creates a lot of timers (with a zero	1287	through AnyEvent. The benchmark creates a lot of timers (with a zero
950	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1288	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
951	which it is), lets them fire exactly once and destroys them again.	1289	which it is), lets them fire exactly once and destroys them again.
952		1290
953	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1291	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
954	distribution.	1292	distribution.
…		…
971	all watchers, to avoid adding memory overhead. That means closure creation	1309	all watchers, to avoid adding memory overhead. That means closure creation
972	and memory usage is not included in the figures.	1310	and memory usage is not included in the figures.
973		1311
974	I<invoke> is the time, in microseconds, used to invoke a simple	1312	I<invoke> is the time, in microseconds, used to invoke a simple
975	callback. The callback simply counts down a Perl variable and after it was	1313	callback. The callback simply counts down a Perl variable and after it was
976	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1314	invoked "watcher" times, it would C<< ->send >> a condvar once to
977	signal the end of this phase.	1315	signal the end of this phase.
978		1316
979	I<destroy> is the time, in microseconds, that it takes to destroy a single	1317	I<destroy> is the time, in microseconds, that it takes to destroy a single
980	watcher.	1318	watcher.
981		1319
…		…
1041	file descriptor is dup()ed for each watcher. This shows that the dup()	1379	file descriptor is dup()ed for each watcher. This shows that the dup()
1042	employed by some adaptors is not a big performance issue (it does incur a	1380	employed by some adaptors is not a big performance issue (it does incur a
1043	hidden memory cost inside the kernel which is not reflected in the figures	1381	hidden memory cost inside the kernel which is not reflected in the figures
1044	above).	1382	above).
1045		1383
1046	C<POE>, regardless of underlying event loop (whether using its pure	1384	C<POE>, regardless of underlying event loop (whether using its pure perl
1047	perl select-based backend or the Event module, the POE-EV backend	1385	select-based backend or the Event module, the POE-EV backend couldn't
1048	couldn't be tested because it wasn't working) shows abysmal performance	1386	be tested because it wasn't working) shows abysmal performance and
1049	and memory usage: Watchers use almost 30 times as much memory as	1387	memory usage with AnyEvent: Watchers use almost 30 times as much memory
1050	EV watchers, and 10 times as much memory as Event (the high memory	1388	as EV watchers, and 10 times as much memory as Event (the high memory
1051	requirements are caused by requiring a session for each watcher). Watcher	1389	requirements are caused by requiring a session for each watcher). Watcher
1052	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1390	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1391	implementation.
		1392
1053	implementation. The design of the POE adaptor class in AnyEvent can not	1393	The design of the POE adaptor class in AnyEvent can not really account
1054	really account for this, as session creation overhead is small compared	1394	for the performance issues, though, as session creation overhead is
1055	to execution of the state machine, which is coded pretty optimally within	1395	small compared to execution of the state machine, which is coded pretty
1056	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1396	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1397	using multiple sessions is not a good approach, especially regarding
		1398	memory usage, even the author of POE could not come up with a faster
		1399	design).
1057		1400
1058	=head3 Summary	1401	=head3 Summary
1059		1402
1060	=over 4	1403	=over 4
1061		1404
…		…
1072		1415
1073	=back	1416	=back
1074		1417
1075	=head2 BENCHMARKING THE LARGE SERVER CASE	1418	=head2 BENCHMARKING THE LARGE SERVER CASE
1076		1419
1077	This benchmark atcually benchmarks the event loop itself. It works by	1420	This benchmark actually benchmarks the event loop itself. It works by
1078	creating a number of "servers": each server consists of a socketpair, a	1421	creating a number of "servers": each server consists of a socket pair, a
1079	timeout watcher that gets reset on activity (but never fires), and an I/O	1422	timeout watcher that gets reset on activity (but never fires), and an I/O
1080	watcher waiting for input on one side of the socket. Each time the socket	1423	watcher waiting for input on one side of the socket. Each time the socket
1081	watcher reads a byte it will write that byte to a random other "server".	1424	watcher reads a byte it will write that byte to a random other "server".
1082		1425
1083	The effect is that there will be a lot of I/O watchers, only part of which	1426	The effect is that there will be a lot of I/O watchers, only part of which
1084	are active at any one point (so there is a constant number of active	1427	are active at any one point (so there is a constant number of active
1085	fds for each loop iterstaion, but which fds these are is random). The	1428	fds for each loop iteration, but which fds these are is random). The
1086	timeout is reset each time something is read because that reflects how	1429	timeout is reset each time something is read because that reflects how
1087	most timeouts work (and puts extra pressure on the event loops).	1430	most timeouts work (and puts extra pressure on the event loops).
1088		1431
1089	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1432	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1090	(1%) are active. This mirrors the activity of large servers with many	1433	(1%) are active. This mirrors the activity of large servers with many
1091	connections, most of which are idle at any one point in time.	1434	connections, most of which are idle at any one point in time.
1092		1435
1093	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1436	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1094	distribution.	1437	distribution.
…		…
1096	=head3 Explanation of the columns	1439	=head3 Explanation of the columns
1097		1440
1098	I<sockets> is the number of sockets, and twice the number of "servers" (as	1441	I<sockets> is the number of sockets, and twice the number of "servers" (as
1099	each server has a read and write socket end).	1442	each server has a read and write socket end).
1100		1443
1101	I<create> is the time it takes to create a socketpair (which is	1444	I<create> is the time it takes to create a socket pair (which is
1102	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1445	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1103		1446
1104	I<request>, the most important value, is the time it takes to handle a	1447	I<request>, the most important value, is the time it takes to handle a
1105	single "request", that is, reading the token from the pipe and forwarding	1448	single "request", that is, reading the token from the pipe and forwarding
1106	it to another server. This includes deleting the old timeout and creating	1449	it to another server. This includes deleting the old timeout and creating
…		…
1140		1483
1141	=head3 Summary	1484	=head3 Summary
1142		1485
1143	=over 4	1486	=over 4
1144		1487
1145	=item * The pure perl implementation performs extremely well, considering	1488	=item * The pure perl implementation performs extremely well.
1146	that it uses select.
1147		1489
1148	=item * Avoid Glib or POE in large projects where performance matters.	1490	=item * Avoid Glib or POE in large projects where performance matters.
1149		1491
1150	=back	1492	=back
1151		1493
…		…
1180	speed most when you have lots of watchers, not when you only have a few of	1522	speed most when you have lots of watchers, not when you only have a few of
1181	them).	1523	them).
1182		1524
1183	EV is again fastest.	1525	EV is again fastest.
1184		1526
1185	The C-based event loops Event and Glib come in second this time, as the	1527	Perl again comes second. It is noticeably faster than the C-based event
1186	overhead of running an iteration is much smaller in C than in Perl (little	1528	loops Event and Glib, although the difference is too small to really
1187	code to execute in the inner loop, and perl's function calling overhead is	1529	matter.
1188	high, and updating all the data structures is costly).
1189
1190	The pure perl event loop is much slower, but still competitive.
1191		1530
1192	POE also performs much better in this case, but is is still far behind the	1531	POE also performs much better in this case, but is is still far behind the
1193	others.	1532	others.
1194		1533
1195	=head3 Summary	1534	=head3 Summary
…		…
1203		1542
1204		1543
1205	=head1 FORK	1544	=head1 FORK
1206		1545
1207	Most event libraries are not fork-safe. The ones who are usually are	1546	Most event libraries are not fork-safe. The ones who are usually are
1208	because they are so inefficient. Only L<EV> is fully fork-aware.	1547	because they rely on inefficient but fork-safe C<select> or C<poll>
		1548	calls. Only L<EV> is fully fork-aware.
1209		1549
1210	If you have to fork, you must either do so I<before> creating your first	1550	If you have to fork, you must either do so I<before> creating your first
1211	watcher OR you must not use AnyEvent at all in the child.	1551	watcher OR you must not use AnyEvent at all in the child.
1212		1552
1213		1553
…		…
1225		1565
1226	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1566	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1227		1567
1228	use AnyEvent;	1568	use AnyEvent;
1229		1569
		1570	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1571	be used to probe what backend is used and gain other information (which is
		1572	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
		1573
1230		1574
1231	=head1 SEE ALSO	1575	=head1 SEE ALSO
1232		1576
1233	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1577	Utility functions: L<AnyEvent::Util>.
1234	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1578
		1579	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1235	L<Event::Lib>, L<Qt>, L<POE>.	1580	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1236		1581
1237	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1582	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1238	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1583	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1239	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1584	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1240	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1585	L<AnyEvent::Impl::POE>.
1241		1586
		1587	Non-blocking file handles, sockets, TCP clients and
		1588	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1589
		1590	Asynchronous DNS: L<AnyEvent::DNS>.
		1591
		1592	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1593
1242	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1594	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1243		1595
1244		1596
1245	=head1 AUTHOR	1597	=head1 AUTHOR
1246		1598
1247	Marc Lehmann <schmorp@schmorp.de>	1599	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.100 by elmex, Sun Apr 27 19:15:43 2008 UTC vs. Revision 1.135 by root, Sun May 25 04:49:01 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.100 by elmex, Sun Apr 27 19:15:43 2008 UTC vs.
Revision 1.135 by root, Sun May 25 04:49:01 2008 UTC