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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.102 by root, Sun Apr 27 21:16:26 2008 UTC vs.
Revision 1.136 by root, Sun May 25 23:52:02 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
…		…
78	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>
79	module.	79	module.
80		80
81	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
82	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
83	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	83	following modules is already loaded: L<EV>,
84	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>,
85	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
86	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
87	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
88	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
…		…
108		108
109	=head1 WATCHERS	109	=head1 WATCHERS
110		110
111	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
112	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
113	the callback to call, the filehandle to watch, etc.	113	the callback to call, the file handle to watch, etc.
114		114
115	These watchers are normal Perl objects with normal Perl lifetime. After	115	These watchers are normal Perl objects with normal Perl lifetime. After
116	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
117	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
118	is in control).	118	is in control).
…		…
237		237
238	Although the callback might get passed parameters, their value and	238	Although the callback might get passed parameters, their value and
239	presence is undefined and you cannot rely on them. Portable AnyEvent	239	presence is undefined and you cannot rely on them. Portable AnyEvent
240	callbacks cannot use arguments passed to signal watcher callbacks.	240	callbacks cannot use arguments passed to signal watcher callbacks.
241		241
242	Multiple signal occurances can be clumped together into one callback	242	Multiple signal occurrences can be clumped together into one callback
243	invocation, and callback invocation will be synchronous. synchronous means	243	invocation, and callback invocation will be synchronous. Synchronous means
244	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,
245	but it is guarenteed not to interrupt any other callbacks.	245	but it is guaranteed not to interrupt any other callbacks.
246		246
247	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
248	between multiple watchers.	248	between multiple watchers.
249		249
250	This watcher might use C<%SIG>, so programs overwriting those signals	250	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
279		279
280	Example: fork a process and wait for it	280	Example: fork a process and wait for it
281		281
282	my $done = AnyEvent->condvar;	282	my $done = AnyEvent->condvar;
283		283
284	AnyEvent::detect; # force event module to be initialised
285
286	my $pid = fork or exit 5;	284	my $pid = fork or exit 5;
287		285
288	my $w = AnyEvent->child (	286	my $w = AnyEvent->child (
289	pid => $pid,	287	pid => $pid,
290	cb => sub {	288	cb => sub {
291	my ($pid, $status) = @_;	289	my ($pid, $status) = @_;
292	warn "pid $pid exited with status $status";	290	warn "pid $pid exited with status $status";
293	$done->broadcast;	291	$done->send;
294	},	292	},
295	);	293	);
296		294
297	# do something else, then wait for process exit	295	# do something else, then wait for process exit
298	$done->wait;	296	$done->recv;
299		297
300	=head2 CONDITION VARIABLES	298	=head2 CONDITION VARIABLES
301		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
302	Condition variables can be created by calling the C<< AnyEvent->condvar >>	310	Condition variables can be created by calling the C<< AnyEvent->condvar
303	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.
304		314
305	A condition variable waits for a condition - precisely that the C<<	315	After creation, the condition variable is "false" until it becomes "true"
306	->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).
307		319
308	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,
309	example, if you write a module that does asynchronous http requests,	328	for example, if you write a module that does asynchronous http requests,
310	then a condition variable would be the ideal candidate to signal the	329	then a condition variable would be the ideal candidate to signal the
311	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.
312		332
313	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,
314	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
315	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
316	->broadcast >> the "quit" event.	336	button of your app, which would C<< ->send >> the "quit" event.
317		337
318	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
319	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
320	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
321	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,
322	as this asks for trouble.	342	as this asks for trouble.
323		343
324	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.
325		385
326	=over 4	386	=over 4
327		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
328	=item $cv->wait	419	=item $cv->end
329		420
330	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 $cv->recv
		478
		479	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
331	called on c<$cv>, while servicing other watchers normally.	480	>> methods have been called on c<$cv>, while servicing other watchers
		481	normally.
332		482
333	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
334	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.
335		491
336	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
337	(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
338	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
339	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
340	condition variables with some kind of request results and supporting	496	condition variables with some kind of request results and supporting
341	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,
342	while still suppporting blocking waits if the caller so desires).	498	while still supporting blocking waits if the caller so desires).
343		499
344	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
345	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
346	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	502	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
347	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	503	can supply.
348	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
349	from different coroutines, however).
350		504
351	=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).
352		510
353	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
354	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
355	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.
356		529
357	=back	530	=back
358
359	Example:
360
361	# wait till the result is ready
362	my $result_ready = AnyEvent->condvar;
363
364	# do something such as adding a timer
365	# or socket watcher the calls $result_ready->broadcast
366	# when the "result" is ready.
367	# in this case, we simply use a timer:
368	my $w = AnyEvent->timer (
369	after => 1,
370	cb => sub { $result_ready->broadcast },
371	);
372
373	# this "blocks" (while handling events) till the watcher
374	# calls broadcast
375	$result_ready->wait;
376		531
377	=head1 GLOBAL VARIABLES AND FUNCTIONS	532	=head1 GLOBAL VARIABLES AND FUNCTIONS
378		533
379	=over 4	534	=over 4
380		535
…		…
386	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	541	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
387	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	542	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
388		543
389	The known classes so far are:	544	The known classes so far are:
390		545
391	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
392	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
393	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	546	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
394	AnyEvent::Impl::Event based on Event, second best choice.	547	AnyEvent::Impl::Event based on Event, second best choice.
		548	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
395	AnyEvent::Impl::Glib based on Glib, third-best choice.	549	AnyEvent::Impl::Glib based on Glib, third-best choice.
396	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
397	AnyEvent::Impl::Tk based on Tk, very bad choice.	550	AnyEvent::Impl::Tk based on Tk, very bad choice.
398	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	551	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
399	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	552	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
400	AnyEvent::Impl::POE based on POE, not generic enough for full support.	553	AnyEvent::Impl::POE based on POE, not generic enough for full support.
401		554
…		…
414	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	567	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
415	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
416	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
417	runtime.	570	runtime.
418		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
419	=back	593	=back
420		594
421	=head1 WHAT TO DO IN A MODULE	595	=head1 WHAT TO DO IN A MODULE
422		596
423	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
…		…
426	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
427	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
428	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
429	to load the event module first.	603	to load the event module first.
430		604
431	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
432	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
433	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
434	events is to stay interactive.	608	events is to stay interactive.
435		609
436	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
437	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
438	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 >>
439	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).
440		614
441	=head1 WHAT TO DO IN THE MAIN PROGRAM	615	=head1 WHAT TO DO IN THE MAIN PROGRAM
442		616
443	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
…		…
445		619
446	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
447	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
448	decide which implementation to chose if some module relies on it.	622	decide which implementation to chose if some module relies on it.
449		623
450	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
451	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
452	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
453	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
454	modules might create watchers when they are loaded, and AnyEvent will	628	modules might create watchers when they are loaded, and AnyEvent will
455	decide on the event model to use as soon as it creates watchers, and it	629	decide on the event model to use as soon as it creates watchers, and it
456	might chose the wrong one unless you load the correct one yourself.	630	might chose the wrong one unless you load the correct one yourself.
457		631
458	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
459	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	633	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
460	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
461		652
462	=head1 OTHER MODULES	653	=head1 OTHER MODULES
463		654
464	The following is a non-exhaustive list of additional modules that use	655	The following is a non-exhaustive list of additional modules that use
465	AnyEvent and can therefore be mixed easily with other AnyEvent modules	656	AnyEvent and can therefore be mixed easily with other AnyEvent modules
…		…
477		668
478	Provide read and write buffers and manages watchers for reads and writes.	669	Provide read and write buffers and manages watchers for reads and writes.
479		670
480	=item L<AnyEvent::Socket>	671	=item L<AnyEvent::Socket>
481		672
482	Provides a means to do non-blocking connects, accepts etc.	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.
483		680
484	=item L<AnyEvent::HTTPD>	681	=item L<AnyEvent::HTTPD>
485		682
486	Provides a simple web application server framework.	683	Provides a simple web application server framework.
487
488	=item L<AnyEvent::DNS>
489
490	Provides asynchronous DNS resolver capabilities, beyond what
491	L<AnyEvent::Util> offers.
492		684
493	=item L<AnyEvent::FastPing>	685	=item L<AnyEvent::FastPing>
494		686
495	The fastest ping in the west.	687	The fastest ping in the west.
496		688
…		…
511		703
512	High level API for event-based execution flow control.	704	High level API for event-based execution flow control.
513		705
514	=item L<Coro>	706	=item L<Coro>
515		707
516	Has special support for AnyEvent.	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.
517		720
518	=item L<IO::Lambda>	721	=item L<IO::Lambda>
519		722
520	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.	723	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
521
522	=item L<IO::AIO>
523
524	Truly asynchronous I/O, should be in the toolbox of every event
525	programmer. Can be trivially made to use AnyEvent.
526
527	=item L<BDB>
528
529	Truly asynchronous Berkeley DB access. Can be trivially made to use
530	AnyEvent.
531		724
532	=back	725	=back
533		726
534	=cut	727	=cut
535		728
…		…
538	no warnings;	731	no warnings;
539	use strict;	732	use strict;
540		733
541	use Carp;	734	use Carp;
542		735
543	our $VERSION = '3.3';	736	our $VERSION = '4.03';
544	our $MODEL;	737	our $MODEL;
545		738
546	our $AUTOLOAD;	739	our $AUTOLOAD;
547	our @ISA;	740	our @ISA;
548		741
		742	our @REGISTRY;
		743
549	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	744	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
550		745
551	our @REGISTRY;	746	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
		747
		748	{
		749	my $idx;
		750	$PROTOCOL{$_} = ++$idx
		751	for reverse split /\s,\s/,
		752	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		753	}
552		754
553	my @models = (	755	my @models = (
554	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
555	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
556	[EV:: => AnyEvent::Impl::EV::],	756	[EV:: => AnyEvent::Impl::EV::],
557	[Event:: => AnyEvent::Impl::Event::],	757	[Event:: => AnyEvent::Impl::Event::],
558	[Glib:: => AnyEvent::Impl::Glib::],
559	[Tk:: => AnyEvent::Impl::Tk::],
560	[Wx:: => AnyEvent::Impl::POE::],
561	[Prima:: => AnyEvent::Impl::POE::],
562	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	758	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
563	# everything below here will not be autoprobed as the pureperl backend should work everywhere	759	# everything below here will not be autoprobed
		760	# as the pureperl backend should work everywhere
		761	# and is usually faster
		762	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		763	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
564	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	764	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
565	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	765	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
566	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	766	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		767	[Wx:: => AnyEvent::Impl::POE::],
		768	[Prima:: => AnyEvent::Impl::POE::],
567	);	769	);
568		770
569	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	771	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
		772
		773	our @post_detect;
		774
		775	sub post_detect(&) {
		776	my ($cb) = @_;
		777
		778	if ($MODEL) {
		779	$cb->();
		780
		781	1
		782	} else {
		783	push @post_detect, $cb;
		784
		785	defined wantarray
		786	? bless \$cb, "AnyEvent::Util::PostDetect"
		787	: ()
		788	}
		789	}
		790
		791	sub AnyEvent::Util::PostDetect::DESTROY {
		792	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		793	}
570		794
571	sub detect() {	795	sub detect() {
572	unless ($MODEL) {	796	unless ($MODEL) {
573	no strict 'refs';	797	no strict 'refs';
574		798
…		…
608	last;	832	last;
609	}	833	}
610	}	834	}
611		835
612	$MODEL	836	$MODEL
613	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";	837	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
614	}	838	}
615	}	839	}
616		840
617	unshift @ISA, $MODEL;	841	unshift @ISA, $MODEL;
618	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	842	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		843
		844	(shift @post_detect)->() while @post_detect;
619	}	845	}
620		846
621	$MODEL	847	$MODEL
622	}	848	}
623		849
…		…
633	$class->$func (@_);	859	$class->$func (@_);
634	}	860	}
635		861
636	package AnyEvent::Base;	862	package AnyEvent::Base;
637		863
638	# default implementation for ->condvar, ->wait, ->broadcast	864	# default implementation for ->condvar
639		865
640	sub condvar {	866	sub condvar {
641	bless \my $flag, "AnyEvent::Base::CondVar"	867	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
642	}
643
644	sub AnyEvent::Base::CondVar::broadcast {
645	${$_[0]}++;
646	}
647
648	sub AnyEvent::Base::CondVar::wait {
649	AnyEvent->one_event while !${$_[0]};
650	}	868	}
651		869
652	# default implementation for ->signal	870	# default implementation for ->signal
653		871
654	our %SIG_CB;	872	our %SIG_CB;
…		…
728	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	946	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
729		947
730	undef $CHLD_W unless keys %PID_CB;	948	undef $CHLD_W unless keys %PID_CB;
731	}	949	}
732		950
		951	package AnyEvent::CondVar;
		952
		953	our @ISA = AnyEvent::CondVar::Base::;
		954
		955	package AnyEvent::CondVar::Base;
		956
		957	use overload
		958	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		959	fallback => 1;
		960
		961	sub _send {
		962	# nop
		963	}
		964
		965	sub send {
		966	my $cv = shift;
		967	$cv->{_ae_sent} = [@_];
		968	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		969	$cv->_send;
		970	}
		971
		972	sub croak {
		973	$_[0]{_ae_croak} = $_[1];
		974	$_[0]->send;
		975	}
		976
		977	sub ready {
		978	$_[0]{_ae_sent}
		979	}
		980
		981	sub _wait {
		982	AnyEvent->one_event while !$_[0]{_ae_sent};
		983	}
		984
		985	sub recv {
		986	$_[0]->_wait;
		987
		988	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		989	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		990	}
		991
		992	sub cb {
		993	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		994	$_[0]{_ae_cb}
		995	}
		996
		997	sub begin {
		998	++$_[0]{_ae_counter};
		999	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1000	}
		1001
		1002	sub end {
		1003	return if --$_[0]{_ae_counter};
		1004	&{ $_[0]{_ae_end_cb} \|\| sub { $_[0]->send } };
		1005	}
		1006
		1007	# undocumented/compatibility with pre-3.4
		1008	*broadcast = \&send;
		1009	*wait = \&_wait;
		1010
733	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1011	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
734		1012
735	This is an advanced topic that you do not normally need to use AnyEvent in	1013	This is an advanced topic that you do not normally need to use AnyEvent in
736	a module. This section is only of use to event loop authors who want to	1014	a module. This section is only of use to event loop authors who want to
737	provide AnyEvent compatibility.	1015	provide AnyEvent compatibility.
…		…
793	model it chooses.	1071	model it chooses.
794		1072
795	=item C<PERL_ANYEVENT_MODEL>	1073	=item C<PERL_ANYEVENT_MODEL>
796		1074
797	This can be used to specify the event model to be used by AnyEvent, before	1075	This can be used to specify the event model to be used by AnyEvent, before
798	autodetection and -probing kicks in. It must be a string consisting	1076	auto detection and -probing kicks in. It must be a string consisting
799	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1077	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
800	and the resulting module name is loaded and if the load was successful,	1078	and the resulting module name is loaded and if the load was successful,
801	used as event model. If it fails to load AnyEvent will proceed with	1079	used as event model. If it fails to load AnyEvent will proceed with
802	autodetection and -probing.	1080	auto detection and -probing.
803		1081
804	This functionality might change in future versions.	1082	This functionality might change in future versions.
805		1083
806	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1084	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
807	could start your program like this:	1085	could start your program like this:
808		1086
809	PERL_ANYEVENT_MODEL=Perl perl ...	1087	PERL_ANYEVENT_MODEL=Perl perl ...
		1088
		1089	=item C<PERL_ANYEVENT_PROTOCOLS>
		1090
		1091	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1092	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1093	of auto probing).
		1094
		1095	Must be set to a comma-separated list of protocols or address families,
		1096	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1097	used, and preference will be given to protocols mentioned earlier in the
		1098	list.
		1099
		1100	This variable can effectively be used for denial-of-service attacks
		1101	against local programs (e.g. when setuid), although the impact is likely
		1102	small, as the program has to handle connection errors already-
		1103
		1104	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1105	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1106	- only support IPv4, never try to resolve or contact IPv6
		1107	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1108	IPv6, but prefer IPv6 over IPv4.
		1109
		1110	=item C<PERL_ANYEVENT_EDNS0>
		1111
		1112	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1113	for DNS. This extension is generally useful to reduce DNS traffic, but
		1114	some (broken) firewalls drop such DNS packets, which is why it is off by
		1115	default.
		1116
		1117	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1118	EDNS0 in its DNS requests.
810		1119
811	=back	1120	=back
812		1121
813	=head1 EXAMPLE PROGRAM	1122	=head1 EXAMPLE PROGRAM
814		1123
…		…
825	poll => 'r',	1134	poll => 'r',
826	cb => sub {	1135	cb => sub {
827	warn "io event <$_[0]>\n"; # will always output <r>	1136	warn "io event <$_[0]>\n"; # will always output <r>
828	chomp (my $input = <STDIN>); # read a line	1137	chomp (my $input = <STDIN>); # read a line
829	warn "read: $input\n"; # output what has been read	1138	warn "read: $input\n"; # output what has been read
830	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1139	$cv->send if $input =~ /^q/i; # quit program if /^q/i
831	},	1140	},
832	);	1141	);
833		1142
834	my $time_watcher; # can only be used once	1143	my $time_watcher; # can only be used once
835		1144
…		…
840	});	1149	});
841	}	1150	}
842		1151
843	new_timer; # create first timer	1152	new_timer; # create first timer
844		1153
845	$cv->wait; # wait until user enters /^q/i	1154	$cv->recv; # wait until user enters /^q/i
846		1155
847	=head1 REAL-WORLD EXAMPLE	1156	=head1 REAL-WORLD EXAMPLE
848		1157
849	Consider the L<Net::FCP> module. It features (among others) the following	1158	Consider the L<Net::FCP> module. It features (among others) the following
850	API calls, which are to freenet what HTTP GET requests are to http:	1159	API calls, which are to freenet what HTTP GET requests are to http:
…		…
900	syswrite $txn->{fh}, $txn->{request}	1209	syswrite $txn->{fh}, $txn->{request}
901	or die "connection or write error";	1210	or die "connection or write error";
902	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1211	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
903		1212
904	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1213	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
905	result and signals any possible waiters that the request ahs finished:	1214	result and signals any possible waiters that the request has finished:
906		1215
907	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1216	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
908		1217
909	if (end-of-file or data complete) {	1218	if (end-of-file or data complete) {
910	$txn->{result} = $txn->{buf};	1219	$txn->{result} = $txn->{buf};
911	$txn->{finished}->broadcast;	1220	$txn->{finished}->send;
912	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1221	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
913	}	1222	}
914		1223
915	The C<result> method, finally, just waits for the finished signal (if the	1224	The C<result> method, finally, just waits for the finished signal (if the
916	request was already finished, it doesn't wait, of course, and returns the	1225	request was already finished, it doesn't wait, of course, and returns the
917	data:	1226	data:
918		1227
919	$txn->{finished}->wait;	1228	$txn->{finished}->recv;
920	return $txn->{result};	1229	return $txn->{result};
921		1230
922	The actual code goes further and collects all errors (C<die>s, exceptions)	1231	The actual code goes further and collects all errors (C<die>s, exceptions)
923	that occured during request processing. The C<result> method detects	1232	that occurred during request processing. The C<result> method detects
924	whether an exception as thrown (it is stored inside the $txn object)	1233	whether an exception as thrown (it is stored inside the $txn object)
925	and just throws the exception, which means connection errors and other	1234	and just throws the exception, which means connection errors and other
926	problems get reported tot he code that tries to use the result, not in a	1235	problems get reported tot he code that tries to use the result, not in a
927	random callback.	1236	random callback.
928		1237
…		…
959		1268
960	my $quit = AnyEvent->condvar;	1269	my $quit = AnyEvent->condvar;
961		1270
962	$fcp->txn_client_get ($url)->cb (sub {	1271	$fcp->txn_client_get ($url)->cb (sub {
963	...	1272	...
964	$quit->broadcast;	1273	$quit->send;
965	});	1274	});
966		1275
967	$quit->wait;	1276	$quit->recv;
968		1277
969		1278
970	=head1 BENCHMARKS	1279	=head1 BENCHMARKS
971		1280
972	To give you an idea of the performance and overheads that AnyEvent adds	1281	To give you an idea of the performance and overheads that AnyEvent adds
…		…
974	of various event loops I prepared some benchmarks.	1283	of various event loops I prepared some benchmarks.
975		1284
976	=head2 BENCHMARKING ANYEVENT OVERHEAD	1285	=head2 BENCHMARKING ANYEVENT OVERHEAD
977		1286
978	Here is a benchmark of various supported event models used natively and	1287	Here is a benchmark of various supported event models used natively and
979	through anyevent. The benchmark creates a lot of timers (with a zero	1288	through AnyEvent. The benchmark creates a lot of timers (with a zero
980	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	1289	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
981	which it is), lets them fire exactly once and destroys them again.	1290	which it is), lets them fire exactly once and destroys them again.
982		1291
983	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1292	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
984	distribution.	1293	distribution.
…		…
1001	all watchers, to avoid adding memory overhead. That means closure creation	1310	all watchers, to avoid adding memory overhead. That means closure creation
1002	and memory usage is not included in the figures.	1311	and memory usage is not included in the figures.
1003		1312
1004	I<invoke> is the time, in microseconds, used to invoke a simple	1313	I<invoke> is the time, in microseconds, used to invoke a simple
1005	callback. The callback simply counts down a Perl variable and after it was	1314	callback. The callback simply counts down a Perl variable and after it was
1006	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1315	invoked "watcher" times, it would C<< ->send >> a condvar once to
1007	signal the end of this phase.	1316	signal the end of this phase.
1008		1317
1009	I<destroy> is the time, in microseconds, that it takes to destroy a single	1318	I<destroy> is the time, in microseconds, that it takes to destroy a single
1010	watcher.	1319	watcher.
1011		1320
…		…
1071	file descriptor is dup()ed for each watcher. This shows that the dup()	1380	file descriptor is dup()ed for each watcher. This shows that the dup()
1072	employed by some adaptors is not a big performance issue (it does incur a	1381	employed by some adaptors is not a big performance issue (it does incur a
1073	hidden memory cost inside the kernel which is not reflected in the figures	1382	hidden memory cost inside the kernel which is not reflected in the figures
1074	above).	1383	above).
1075		1384
1076	C<POE>, regardless of underlying event loop (whether using its pure	1385	C<POE>, regardless of underlying event loop (whether using its pure perl
1077	perl select-based backend or the Event module, the POE-EV backend	1386	select-based backend or the Event module, the POE-EV backend couldn't
1078	couldn't be tested because it wasn't working) shows abysmal performance	1387	be tested because it wasn't working) shows abysmal performance and
1079	and memory usage: Watchers use almost 30 times as much memory as	1388	memory usage with AnyEvent: Watchers use almost 30 times as much memory
1080	EV watchers, and 10 times as much memory as Event (the high memory	1389	as EV watchers, and 10 times as much memory as Event (the high memory
1081	requirements are caused by requiring a session for each watcher). Watcher	1390	requirements are caused by requiring a session for each watcher). Watcher
1082	invocation speed is almost 900 times slower than with AnyEvent's pure perl	1391	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1392	implementation.
		1393
1083	implementation. The design of the POE adaptor class in AnyEvent can not	1394	The design of the POE adaptor class in AnyEvent can not really account
1084	really account for this, as session creation overhead is small compared	1395	for the performance issues, though, as session creation overhead is
1085	to execution of the state machine, which is coded pretty optimally within	1396	small compared to execution of the state machine, which is coded pretty
1086	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1397	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1398	using multiple sessions is not a good approach, especially regarding
		1399	memory usage, even the author of POE could not come up with a faster
		1400	design).
1087		1401
1088	=head3 Summary	1402	=head3 Summary
1089		1403
1090	=over 4	1404	=over 4
1091		1405
…		…
1102		1416
1103	=back	1417	=back
1104		1418
1105	=head2 BENCHMARKING THE LARGE SERVER CASE	1419	=head2 BENCHMARKING THE LARGE SERVER CASE
1106		1420
1107	This benchmark atcually benchmarks the event loop itself. It works by	1421	This benchmark actually benchmarks the event loop itself. It works by
1108	creating a number of "servers": each server consists of a socketpair, a	1422	creating a number of "servers": each server consists of a socket pair, a
1109	timeout watcher that gets reset on activity (but never fires), and an I/O	1423	timeout watcher that gets reset on activity (but never fires), and an I/O
1110	watcher waiting for input on one side of the socket. Each time the socket	1424	watcher waiting for input on one side of the socket. Each time the socket
1111	watcher reads a byte it will write that byte to a random other "server".	1425	watcher reads a byte it will write that byte to a random other "server".
1112		1426
1113	The effect is that there will be a lot of I/O watchers, only part of which	1427	The effect is that there will be a lot of I/O watchers, only part of which
1114	are active at any one point (so there is a constant number of active	1428	are active at any one point (so there is a constant number of active
1115	fds for each loop iterstaion, but which fds these are is random). The	1429	fds for each loop iteration, but which fds these are is random). The
1116	timeout is reset each time something is read because that reflects how	1430	timeout is reset each time something is read because that reflects how
1117	most timeouts work (and puts extra pressure on the event loops).	1431	most timeouts work (and puts extra pressure on the event loops).
1118		1432
1119	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1433	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1120	(1%) are active. This mirrors the activity of large servers with many	1434	(1%) are active. This mirrors the activity of large servers with many
1121	connections, most of which are idle at any one point in time.	1435	connections, most of which are idle at any one point in time.
1122		1436
1123	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1437	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1124	distribution.	1438	distribution.
…		…
1126	=head3 Explanation of the columns	1440	=head3 Explanation of the columns
1127		1441
1128	I<sockets> is the number of sockets, and twice the number of "servers" (as	1442	I<sockets> is the number of sockets, and twice the number of "servers" (as
1129	each server has a read and write socket end).	1443	each server has a read and write socket end).
1130		1444
1131	I<create> is the time it takes to create a socketpair (which is	1445	I<create> is the time it takes to create a socket pair (which is
1132	nontrivial) and two watchers: an I/O watcher and a timeout watcher.	1446	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1133		1447
1134	I<request>, the most important value, is the time it takes to handle a	1448	I<request>, the most important value, is the time it takes to handle a
1135	single "request", that is, reading the token from the pipe and forwarding	1449	single "request", that is, reading the token from the pipe and forwarding
1136	it to another server. This includes deleting the old timeout and creating	1450	it to another server. This includes deleting the old timeout and creating
…		…
1170		1484
1171	=head3 Summary	1485	=head3 Summary
1172		1486
1173	=over 4	1487	=over 4
1174		1488
1175	=item * The pure perl implementation performs extremely well, considering	1489	=item * The pure perl implementation performs extremely well.
1176	that it uses select.
1177		1490
1178	=item * Avoid Glib or POE in large projects where performance matters.	1491	=item * Avoid Glib or POE in large projects where performance matters.
1179		1492
1180	=back	1493	=back
1181		1494
…		…
1210	speed most when you have lots of watchers, not when you only have a few of	1523	speed most when you have lots of watchers, not when you only have a few of
1211	them).	1524	them).
1212		1525
1213	EV is again fastest.	1526	EV is again fastest.
1214		1527
1215	Perl again comes second. It is noticably faster than the C-based event	1528	Perl again comes second. It is noticeably faster than the C-based event
1216	loops Event and Glib, although the difference is too small to really	1529	loops Event and Glib, although the difference is too small to really
1217	matter.	1530	matter.
1218		1531
1219	POE also performs much better in this case, but is is still far behind the	1532	POE also performs much better in this case, but is is still far behind the
1220	others.	1533	others.
…		…
1230		1543
1231		1544
1232	=head1 FORK	1545	=head1 FORK
1233		1546
1234	Most event libraries are not fork-safe. The ones who are usually are	1547	Most event libraries are not fork-safe. The ones who are usually are
1235	because they are so inefficient. Only L<EV> is fully fork-aware.	1548	because they rely on inefficient but fork-safe C<select> or C<poll>
		1549	calls. Only L<EV> is fully fork-aware.
1236		1550
1237	If you have to fork, you must either do so I<before> creating your first	1551	If you have to fork, you must either do so I<before> creating your first
1238	watcher OR you must not use AnyEvent at all in the child.	1552	watcher OR you must not use AnyEvent at all in the child.
1239		1553
1240		1554
…		…
1252		1566
1253	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1567	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1254		1568
1255	use AnyEvent;	1569	use AnyEvent;
1256		1570
		1571	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1572	be used to probe what backend is used and gain other information (which is
		1573	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
		1574
1257		1575
1258	=head1 SEE ALSO	1576	=head1 SEE ALSO
1259		1577
1260	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1578	Utility functions: L<AnyEvent::Util>.
1261	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1579
		1580	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1262	L<Event::Lib>, L<Qt>, L<POE>.	1581	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1263		1582
1264	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1583	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1265	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1584	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1266	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1585	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1267	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1586	L<AnyEvent::Impl::POE>.
1268		1587
		1588	Non-blocking file handles, sockets, TCP clients and
		1589	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1590
		1591	Asynchronous DNS: L<AnyEvent::DNS>.
		1592
		1593	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1594
1269	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1595	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1270		1596
1271		1597
1272	=head1 AUTHOR	1598	=head1 AUTHOR
1273		1599
1274	Marc Lehmann <schmorp@schmorp.de>	1600	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.102 by root, Sun Apr 27 21:16:26 2008 UTC vs. Revision 1.136 by root, Sun May 25 23:52:02 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.102 by root, Sun Apr 27 21:16:26 2008 UTC vs.
Revision 1.136 by root, Sun May 25 23:52:02 2008 UTC