[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 1.142 by root, Tue May 27 02:34:30 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?
…		…
48	isn't itself. What's worse, all the potential users of your module are	48	isn't itself. What's worse, all the potential users of your module are
49	I<also> forced to use the same event loop you use.	49	I<also> forced to use the same event loop you use.
50		50
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if	53	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	54	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	55	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	56	event models it supports (including stuff like POE and IO::Async, as long
57	as those use one of the supported event loops. It is trivial to add new	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, AnyEvent comes with a big (and fully optional!) toolbox
		68	of useful functionality, such as an asynchronous DNS resolver, 100%
		69	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		70	such as Windows) and lots of real-world knowledge and workarounds for
		71	platform bugs and differences.
		72
67	Of course, if you want lots of policy (this can arguably be somewhat	73	Now, if you I<do want> lots of policy (this can arguably be somewhat
68	useful) and you want to force your users to use the one and only event	74	useful) and you want to force your users to use the one and only event
69	model, you should I<not> use this module.	75	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		76
91	=head1 DESCRIPTION	77	=head1 DESCRIPTION
92		78
93	L<AnyEvent> provides an identical interface to multiple event loops. This	79	L<AnyEvent> provides an identical interface to multiple event loops. This
94	allows module authors to utilise an event loop without forcing module	80	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>	84	The interface itself is vaguely similar, but not identical to the L<Event>
99	module.	85	module.
100		86
101	During the first call of any watcher-creation method, the module tries	87	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	88	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>,	89	following modules is already loaded: L<EV>,
104	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,	90	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	91	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	92	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	93	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	94	be successfully loaded will be used. If, after this, still none could be
…		…
122	starts using it, all bets are off. Maybe you should tell their authors to	108	starts using it, all bets are off. Maybe you should tell their authors to
123	use AnyEvent so their modules work together with others seamlessly...	109	use AnyEvent so their modules work together with others seamlessly...
124		110
125	The pure-perl implementation of AnyEvent is called	111	The pure-perl implementation of AnyEvent is called
126	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	112	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
127	explicitly.	113	explicitly and enjoy the high availability of that event loop :)
128		114
129	=head1 WATCHERS	115	=head1 WATCHERS
130		116
131	AnyEvent has the central concept of a I<watcher>, which is an object that	117	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	118	stores relevant data for each kind of event you are waiting for, such as
133	the callback to call, the filehandle to watch, etc.	119	the callback to call, the file handle to watch, etc.
134		120
135	These watchers are normal Perl objects with normal Perl lifetime. After	121	These watchers are normal Perl objects with normal Perl lifetime. After
136	creating a watcher it will immediately "watch" for events and invoke the	122	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	123	callback when the event occurs (of course, only when the event model
138	is in control).	124	is in control).
…		…
257		243
258	Although the callback might get passed parameters, their value and	244	Although the callback might get passed parameters, their value and
259	presence is undefined and you cannot rely on them. Portable AnyEvent	245	presence is undefined and you cannot rely on them. Portable AnyEvent
260	callbacks cannot use arguments passed to signal watcher callbacks.	246	callbacks cannot use arguments passed to signal watcher callbacks.
261		247
262	Multiple signal occurances can be clumped together into one callback	248	Multiple signal occurrences can be clumped together into one callback
263	invocation, and callback invocation will be synchronous. synchronous means	249	invocation, and callback invocation will be synchronous. Synchronous means
264	that it might take a while until the signal gets handled by the process,	250	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.	251	but it is guaranteed not to interrupt any other callbacks.
266		252
267	The main advantage of using these watchers is that you can share a signal	253	The main advantage of using these watchers is that you can share a signal
268	between multiple watchers.	254	between multiple watchers.
269		255
270	This watcher might use C<%SIG>, so programs overwriting those signals	256	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
299		285
300	Example: fork a process and wait for it	286	Example: fork a process and wait for it
301		287
302	my $done = AnyEvent->condvar;	288	my $done = AnyEvent->condvar;
303		289
304	AnyEvent::detect; # force event module to be initialised
305
306	my $pid = fork or exit 5;	290	my $pid = fork or exit 5;
307		291
308	my $w = AnyEvent->child (	292	my $w = AnyEvent->child (
309	pid => $pid,	293	pid => $pid,
310	cb => sub {	294	cb => sub {
311	my ($pid, $status) = @_;	295	my ($pid, $status) = @_;
312	warn "pid $pid exited with status $status";	296	warn "pid $pid exited with status $status";
313	$done->broadcast;	297	$done->send;
314	},	298	},
315	);	299	);
316		300
317	# do something else, then wait for process exit	301	# do something else, then wait for process exit
318	$done->wait;	302	$done->recv;
319		303
320	=head2 CONDITION VARIABLES	304	=head2 CONDITION VARIABLES
321		305
		306	If you are familiar with some event loops you will know that all of them
		307	require you to run some blocking "loop", "run" or similar function that
		308	will actively watch for new events and call your callbacks.
		309
		310	AnyEvent is different, it expects somebody else to run the event loop and
		311	will only block when necessary (usually when told by the user).
		312
		313	The instrument to do that is called a "condition variable", so called
		314	because they represent a condition that must become true.
		315
322	Condition variables can be created by calling the C<< AnyEvent->condvar >>	316	Condition variables can be created by calling the C<< AnyEvent->condvar
323	method without any arguments.	317	>> method, usually without arguments. The only argument pair allowed is
		318	C<cb>, which specifies a callback to be called when the condition variable
		319	becomes true.
324		320
325	A condition variable waits for a condition - precisely that the C<<	321	After creation, the condition variable is "false" until it becomes "true"
326	->broadcast >> method has been called.	322	by calling the C<send> method (or calling the condition variable as if it
		323	were a callback, read about the caveats in the description for the C<<
		324	->send >> method).
327		325
328	They are very useful to signal that a condition has been fulfilled, for	326	Condition variables are similar to callbacks, except that you can
		327	optionally wait for them. They can also be called merge points - points
		328	in time where multiple outstanding events have been processed. And yet
		329	another way to call them is transactions - each condition variable can be
		330	used to represent a transaction, which finishes at some point and delivers
		331	a result.
		332
		333	Condition variables are very useful to signal that something has finished,
329	example, if you write a module that does asynchronous http requests,	334	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	335	then a condition variable would be the ideal candidate to signal the
331	availability of results.	336	availability of results. The user can either act when the callback is
		337	called or can synchronously C<< ->recv >> for the results.
332		338
333	You can also use condition variables to block your main program until	339	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	340	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<<	341	could C<< ->recv >> in your main program until the user clicks the Quit
336	->broadcast >> the "quit" event.	342	button of your app, which would C<< ->send >> the "quit" event.
337		343
338	Note that condition variables recurse into the event loop - if you have	344	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	345	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	346	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,	347	you should avoid making a blocking wait yourself, at least in callbacks,
342	as this asks for trouble.	348	as this asks for trouble.
343		349
344	This object has two methods:	350	Condition variables are represented by hash refs in perl, and the keys
		351	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		352	easy (it is often useful to build your own transaction class on top of
		353	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		354	it's C<new> method in your own C<new> method.
		355
		356	There are two "sides" to a condition variable - the "producer side" which
		357	eventually calls C<< -> send >>, and the "consumer side", which waits
		358	for the send to occur.
		359
		360	Example: wait for a timer.
		361
		362	# wait till the result is ready
		363	my $result_ready = AnyEvent->condvar;
		364
		365	# do something such as adding a timer
		366	# or socket watcher the calls $result_ready->send
		367	# when the "result" is ready.
		368	# in this case, we simply use a timer:
		369	my $w = AnyEvent->timer (
		370	after => 1,
		371	cb => sub { $result_ready->send },
		372	);
		373
		374	# this "blocks" (while handling events) till the callback
		375	# calls send
		376	$result_ready->recv;
		377
		378	Example: wait for a timer, but take advantage of the fact that
		379	condition variables are also code references.
		380
		381	my $done = AnyEvent->condvar;
		382	my $delay = AnyEvent->timer (after => 5, cb => $done);
		383	$done->recv;
		384
		385	=head3 METHODS FOR PRODUCERS
		386
		387	These methods should only be used by the producing side, i.e. the
		388	code/module that eventually sends the signal. Note that it is also
		389	the producer side which creates the condvar in most cases, but it isn't
		390	uncommon for the consumer to create it as well.
345		391
346	=over 4	392	=over 4
347		393
		394	=item $cv->send (...)
		395
		396	Flag the condition as ready - a running C<< ->recv >> and all further
		397	calls to C<recv> will (eventually) return after this method has been
		398	called. If nobody is waiting the send will be remembered.
		399
		400	If a callback has been set on the condition variable, it is called
		401	immediately from within send.
		402
		403	Any arguments passed to the C<send> call will be returned by all
		404	future C<< ->recv >> calls.
		405
		406	Condition variables are overloaded so one can call them directly
		407	(as a code reference). Calling them directly is the same as calling
		408	C<send>. Note, however, that many C-based event loops do not handle
		409	overloading, so as tempting as it may be, passing a condition variable
		410	instead of a callback does not work. Both the pure perl and EV loops
		411	support overloading, however, as well as all functions that use perl to
		412	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		413	example).
		414
		415	=item $cv->croak ($error)
		416
		417	Similar to send, but causes all call's to C<< ->recv >> to invoke
		418	C<Carp::croak> with the given error message/object/scalar.
		419
		420	This can be used to signal any errors to the condition variable
		421	user/consumer.
		422
		423	=item $cv->begin ([group callback])
		424
348	=item $cv->wait	425	=item $cv->end
349		426
350	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	427	These two methods are EXPERIMENTAL and MIGHT CHANGE.
		428
		429	These two methods can be used to combine many transactions/events into
		430	one. For example, a function that pings many hosts in parallel might want
		431	to use a condition variable for the whole process.
		432
		433	Every call to C<< ->begin >> will increment a counter, and every call to
		434	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		435	>>, the (last) callback passed to C<begin> will be executed. That callback
		436	is I<supposed> to call C<< ->send >>, but that is not required. If no
		437	callback was set, C<send> will be called without any arguments.
		438
		439	Let's clarify this with the ping example:
		440
		441	my $cv = AnyEvent->condvar;
		442
		443	my %result;
		444	$cv->begin (sub { $cv->send (\%result) });
		445
		446	for my $host (@list_of_hosts) {
		447	$cv->begin;
		448	ping_host_then_call_callback $host, sub {
		449	$result{$host} = ...;
		450	$cv->end;
		451	};
		452	}
		453
		454	$cv->end;
		455
		456	This code fragment supposedly pings a number of hosts and calls
		457	C<send> after results for all then have have been gathered - in any
		458	order. To achieve this, the code issues a call to C<begin> when it starts
		459	each ping request and calls C<end> when it has received some result for
		460	it. Since C<begin> and C<end> only maintain a counter, the order in which
		461	results arrive is not relevant.
		462
		463	There is an additional bracketing call to C<begin> and C<end> outside the
		464	loop, which serves two important purposes: first, it sets the callback
		465	to be called once the counter reaches C<0>, and second, it ensures that
		466	C<send> is called even when C<no> hosts are being pinged (the loop
		467	doesn't execute once).
		468
		469	This is the general pattern when you "fan out" into multiple subrequests:
		470	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>
		471	is called at least once, and then, for each subrequest you start, call
		472	C<begin> and for each subrequest you finish, call C<end>.
		473
		474	=back
		475
		476	=head3 METHODS FOR CONSUMERS
		477
		478	These methods should only be used by the consuming side, i.e. the
		479	code awaits the condition.
		480
		481	=over 4
		482
		483	=item $cv->recv
		484
		485	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
351	called on c<$cv>, while servicing other watchers normally.	486	>> methods have been called on c<$cv>, while servicing other watchers
		487	normally.
352		488
353	You can only wait once on a condition - additional calls will return	489	You can only wait once on a condition - additional calls are valid but
354	immediately.	490	will return immediately.
		491
		492	If an error condition has been set by calling C<< ->croak >>, then this
		493	function will call C<croak>.
		494
		495	In list context, all parameters passed to C<send> will be returned,
		496	in scalar context only the first one will be returned.
355		497
356	Not all event models support a blocking wait - some die in that case	498	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	499	(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	500	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	501	caller decide whether the call will block or not (for example, by coupling
360	condition variables with some kind of request results and supporting	502	condition variables with some kind of request results and supporting
361	callbacks so the caller knows that getting the result will not block,	503	callbacks so the caller knows that getting the result will not block,
362	while still suppporting blocking waits if the caller so desires).	504	while still supporting blocking waits if the caller so desires).
363		505
364	Another reason I<never> to C<< ->wait >> in a module is that you cannot	506	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	507	sensibly have two C<< ->recv >>'s in parallel, as that would require
366	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	508	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
367	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	509	can supply.
368	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
369	from different coroutines, however).
370		510
371	=item $cv->broadcast	511	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		512	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		513	versions and also integrates coroutines into AnyEvent, making blocking
		514	C<< ->recv >> calls perfectly safe as long as they are done from another
		515	coroutine (one that doesn't run the event loop).
372		516
373	Flag the condition as ready - a running C<< ->wait >> and all further	517	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	518	only calling C<< ->recv >> from within that callback (or at a later
375	called. If nobody is waiting the broadcast will be remembered..	519	time). This will work even when the event loop does not support blocking
		520	waits otherwise.
		521
		522	=item $bool = $cv->ready
		523
		524	Returns true when the condition is "true", i.e. whether C<send> or
		525	C<croak> have been called.
		526
		527	=item $cb = $cv->cb ([new callback])
		528
		529	This is a mutator function that returns the callback set and optionally
		530	replaces it before doing so.
		531
		532	The callback will be called when the condition becomes "true", i.e. when
		533	C<send> or C<croak> are called. Calling C<recv> inside the callback
		534	or at any later time is guaranteed not to block.
376		535
377	=back	536	=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	$result_ready->wait;
396		537
397	=head1 GLOBAL VARIABLES AND FUNCTIONS	538	=head1 GLOBAL VARIABLES AND FUNCTIONS
398		539
399	=over 4	540	=over 4
400		541
…		…
406	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	547	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
407	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	548	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
408		549
409	The known classes so far are:	550	The known classes so far are:
410		551
411	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
412	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
413	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	552	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
414	AnyEvent::Impl::Event based on Event, second best choice.	553	AnyEvent::Impl::Event based on Event, second best choice.
		554	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
415	AnyEvent::Impl::Glib based on Glib, third-best choice.	555	AnyEvent::Impl::Glib based on Glib, third-best choice.
416	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
417	AnyEvent::Impl::Tk based on Tk, very bad choice.	556	AnyEvent::Impl::Tk based on Tk, very bad choice.
418	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	557	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
419	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	558	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
420	AnyEvent::Impl::POE based on POE, not generic enough for full support.	559	AnyEvent::Impl::POE based on POE, not generic enough for full support.
421		560
…		…
434	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	573	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
435	if necessary. You should only call this function right before you would	574	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	575	have created an AnyEvent watcher anyway, that is, as late as possible at
437	runtime.	576	runtime.
438		577
		578	=item $guard = AnyEvent::post_detect { BLOCK }
		579
		580	Arranges for the code block to be executed as soon as the event model is
		581	autodetected (or immediately if this has already happened).
		582
		583	If called in scalar or list context, then it creates and returns an object
		584	that automatically removes the callback again when it is destroyed. See
		585	L<Coro::BDB> for a case where this is useful.
		586
		587	=item @AnyEvent::post_detect
		588
		589	If there are any code references in this array (you can C<push> to it
		590	before or after loading AnyEvent), then they will called directly after
		591	the event loop has been chosen.
		592
		593	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		594	if it contains a true value then the event loop has already been detected,
		595	and the array will be ignored.
		596
		597	Best use C<AnyEvent::post_detect { BLOCK }> instead.
		598
439	=back	599	=back
440		600
441	=head1 WHAT TO DO IN A MODULE	601	=head1 WHAT TO DO IN A MODULE
442		602
443	As a module author, you should C<use AnyEvent> and call AnyEvent methods	603	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	606	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	607	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	608	by calling AnyEvent in your module body you force the user of your module
449	to load the event module first.	609	to load the event module first.
450		610
451	Never call C<< ->wait >> on a condition variable unless you I<know> that	611	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	612	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	613	because it will stall the whole program, and the whole point of using
454	events is to stay interactive.	614	events is to stay interactive.
455		615
456	It is fine, however, to call C<< ->wait >> when the user of your module	616	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	617	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 >>	618	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).	619	freely, as the user of your module knows what she is doing. always).
460		620
461	=head1 WHAT TO DO IN THE MAIN PROGRAM	621	=head1 WHAT TO DO IN THE MAIN PROGRAM
462		622
463	There will always be a single main program - the only place that should	623	There will always be a single main program - the only place that should
…		…
465		625
466	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	626	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	627	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.	628	decide which implementation to chose if some module relies on it.
469		629
470	If the main program relies on a specific event model. For example, in	630	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	631	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	632	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	633	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	634	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	635	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.	636	might chose the wrong one unless you load the correct one yourself.
477		637
478	You can chose to use a rather inefficient pure-perl implementation by	638	You can chose to use a pure-perl implementation by loading the
479	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	639	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
480	behaviour everywhere, but letting AnyEvent chose is generally better.	640	everywhere, but letting AnyEvent chose the model is generally better.
		641
		642	=head2 MAINLOOP EMULATION
		643
		644	Sometimes (often for short test scripts, or even standalone programs who
		645	only want to use AnyEvent), you do not want to run a specific event loop.
		646
		647	In that case, you can use a condition variable like this:
		648
		649	AnyEvent->condvar->recv;
		650
		651	This has the effect of entering the event loop and looping forever.
		652
		653	Note that usually your program has some exit condition, in which case
		654	it is better to use the "traditional" approach of storing a condition
		655	variable somewhere, waiting for it, and sending it when the program should
		656	exit cleanly.
		657
481		658
482	=head1 OTHER MODULES	659	=head1 OTHER MODULES
483		660
484	L<AnyEvent> itself comes with useful utility modules:	661	The following is a non-exhaustive list of additional modules that use
485		662	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>	663	in the same program. Some of the modules come with AnyEvent, some are
487	and L<AnyEvent::Socket> are provided. L<AnyEvent::Handle> provides	664	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		665
494	=over 4	666	=over 4
495		667
		668	=item L<AnyEvent::Util>
		669
		670	Contains various utility functions that replace often-used but blocking
		671	functions such as C<inet_aton> by event-/callback-based versions.
		672
		673	=item L<AnyEvent::Handle>
		674
		675	Provide read and write buffers and manages watchers for reads and writes.
		676
		677	=item L<AnyEvent::Socket>
		678
		679	Provides various utility functions for (internet protocol) sockets,
		680	addresses and name resolution. Also functions to create non-blocking tcp
		681	connections or tcp servers, with IPv6 and SRV record support and more.
		682
		683	=item L<AnyEvent::DNS>
		684
		685	Provides rich asynchronous DNS resolver capabilities.
		686
		687	=item L<AnyEvent::HTTPD>
		688
		689	Provides a simple web application server framework.
		690
496	=item L<AnyEvent::FastPing>	691	=item L<AnyEvent::FastPing>
497		692
		693	The fastest ping in the west.
		694
498	=item L<Net::IRC3>	695	=item L<Net::IRC3>
499		696
		697	AnyEvent based IRC client module family.
		698
500	=item L<Net::XMPP2>	699	=item L<Net::XMPP2>
		700
		701	AnyEvent based XMPP (Jabber protocol) module family.
		702
		703	=item L<Net::FCP>
		704
		705	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		706	of AnyEvent.
		707
		708	=item L<Event::ExecFlow>
		709
		710	High level API for event-based execution flow control.
		711
		712	=item L<Coro>
		713
		714	Has special support for AnyEvent via L<Coro::AnyEvent>.
		715
		716	=item L<AnyEvent::AIO>, L<IO::AIO>
		717
		718	Truly asynchronous I/O, should be in the toolbox of every event
		719	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
		720	together.
		721
		722	=item L<AnyEvent::BDB>, L<BDB>
		723
		724	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
		725	IO::AIO and AnyEvent together.
		726
		727	=item L<IO::Lambda>
		728
		729	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
501		730
502	=back	731	=back
503		732
504	=cut	733	=cut
505		734
…		…
508	no warnings;	737	no warnings;
509	use strict;	738	use strict;
510		739
511	use Carp;	740	use Carp;
512		741
513	our $VERSION = '3.3';	742	our $VERSION = '4.05';
514	our $MODEL;	743	our $MODEL;
515		744
516	our $AUTOLOAD;	745	our $AUTOLOAD;
517	our @ISA;	746	our @ISA;
518		747
		748	our @REGISTRY;
		749
		750	our $WIN32;
		751
		752	BEGIN {
		753	my $win32 = ! ! ($^O =~ /mswin32/i);
		754	eval "sub WIN32(){ $win32 }";
		755	}
		756
519	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	757	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
520		758
521	our @REGISTRY;	759	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
		760
		761	{
		762	my $idx;
		763	$PROTOCOL{$_} = ++$idx
		764	for reverse split /\s,\s/,
		765	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		766	}
522		767
523	my @models = (	768	my @models = (
524	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
525	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
526	[EV:: => AnyEvent::Impl::EV::],	769	[EV:: => AnyEvent::Impl::EV::],
527	[Event:: => AnyEvent::Impl::Event::],	770	[Event:: => AnyEvent::Impl::Event::],
528	[Glib:: => AnyEvent::Impl::Glib::],
529	[Tk:: => AnyEvent::Impl::Tk::],
530	[Wx:: => AnyEvent::Impl::POE::],
531	[Prima:: => AnyEvent::Impl::POE::],
532	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	771	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
533	# everything below here will not be autoprobed as the pureperl backend should work everywhere	772	# everything below here will not be autoprobed
		773	# as the pureperl backend should work everywhere
		774	# and is usually faster
		775	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		776	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
534	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	777	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
535	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	778	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
536	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	779	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		780	[Wx:: => AnyEvent::Impl::POE::],
		781	[Prima:: => AnyEvent::Impl::POE::],
537	);	782	);
538		783
539	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);	784	our %method = map +($_ => 1), qw(io timer signal child condvar one_event DESTROY);
		785
		786	our @post_detect;
		787
		788	sub post_detect(&) {
		789	my ($cb) = @_;
		790
		791	if ($MODEL) {
		792	$cb->();
		793
		794	1
		795	} else {
		796	push @post_detect, $cb;
		797
		798	defined wantarray
		799	? bless \$cb, "AnyEvent::Util::PostDetect"
		800	: ()
		801	}
		802	}
		803
		804	sub AnyEvent::Util::PostDetect::DESTROY {
		805	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		806	}
540		807
541	sub detect() {	808	sub detect() {
542	unless ($MODEL) {	809	unless ($MODEL) {
543	no strict 'refs';	810	no strict 'refs';
		811	local $SIG{__DIE__};
544		812
545	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	813	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
546	my $model = "AnyEvent::Impl::$1";	814	my $model = "AnyEvent::Impl::$1";
547	if (eval "require $model") {	815	if (eval "require $model") {
548	$MODEL = $model;	816	$MODEL = $model;
…		…
578	last;	846	last;
579	}	847	}
580	}	848	}
581		849
582	$MODEL	850	$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.";	851	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";
584	}	852	}
585	}	853	}
586		854
587	unshift @ISA, $MODEL;	855	unshift @ISA, $MODEL;
588	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	856	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		857
		858	(shift @post_detect)->() while @post_detect;
589	}	859	}
590		860
591	$MODEL	861	$MODEL
592	}	862	}
593		863
…		…
603	$class->$func (@_);	873	$class->$func (@_);
604	}	874	}
605		875
606	package AnyEvent::Base;	876	package AnyEvent::Base;
607		877
608	# default implementation for ->condvar, ->wait, ->broadcast	878	# default implementation for ->condvar
609		879
610	sub condvar {	880	sub condvar {
611	bless \my $flag, "AnyEvent::Base::CondVar"	881	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	}	882	}
621		883
622	# default implementation for ->signal	884	# default implementation for ->signal
623		885
624	our %SIG_CB;	886	our %SIG_CB;
…		…
677	or Carp::croak "required option 'pid' is missing";	939	or Carp::croak "required option 'pid' is missing";
678		940
679	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	941	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
680		942
681	unless ($WNOHANG) {	943	unless ($WNOHANG) {
682	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	944	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
683	}	945	}
684		946
685	unless ($CHLD_W) {	947	unless ($CHLD_W) {
686	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	948	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
687	# child could be a zombie already, so make at least one round	949	# child could be a zombie already, so make at least one round
…		…
697	delete $PID_CB{$pid}{$cb};	959	delete $PID_CB{$pid}{$cb};
698	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	960	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
699		961
700	undef $CHLD_W unless keys %PID_CB;	962	undef $CHLD_W unless keys %PID_CB;
701	}	963	}
		964
		965	package AnyEvent::CondVar;
		966
		967	our @ISA = AnyEvent::CondVar::Base::;
		968
		969	package AnyEvent::CondVar::Base;
		970
		971	use overload
		972	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		973	fallback => 1;
		974
		975	sub _send {
		976	# nop
		977	}
		978
		979	sub send {
		980	my $cv = shift;
		981	$cv->{_ae_sent} = [@_];
		982	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		983	$cv->_send;
		984	}
		985
		986	sub croak {
		987	$_[0]{_ae_croak} = $_[1];
		988	$_[0]->send;
		989	}
		990
		991	sub ready {
		992	$_[0]{_ae_sent}
		993	}
		994
		995	sub _wait {
		996	AnyEvent->one_event while !$_[0]{_ae_sent};
		997	}
		998
		999	sub recv {
		1000	$_[0]->_wait;
		1001
		1002	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1003	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1004	}
		1005
		1006	sub cb {
		1007	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1008	$_[0]{_ae_cb}
		1009	}
		1010
		1011	sub begin {
		1012	++$_[0]{_ae_counter};
		1013	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1014	}
		1015
		1016	sub end {
		1017	return if --$_[0]{_ae_counter};
		1018	&{ $_[0]{_ae_end_cb} \|\| sub { $_[0]->send } };
		1019	}
		1020
		1021	# undocumented/compatibility with pre-3.4
		1022	*broadcast = \&send;
		1023	*wait = \&_wait;
702		1024
703	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1025	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
704		1026
705	This is an advanced topic that you do not normally need to use AnyEvent in	1027	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	1028	a module. This section is only of use to event loop authors who want to
…		…
763	model it chooses.	1085	model it chooses.
764		1086
765	=item C<PERL_ANYEVENT_MODEL>	1087	=item C<PERL_ANYEVENT_MODEL>
766		1088
767	This can be used to specify the event model to be used by AnyEvent, before	1089	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	1090	auto detection and -probing kicks in. It must be a string consisting
769	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1091	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,	1092	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	1093	used as event model. If it fails to load AnyEvent will proceed with
772	autodetection and -probing.	1094	auto detection and -probing.
773		1095
774	This functionality might change in future versions.	1096	This functionality might change in future versions.
775		1097
776	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you	1098	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
777	could start your program like this:	1099	could start your program like this:
778		1100
779	PERL_ANYEVENT_MODEL=Perl perl ...	1101	PERL_ANYEVENT_MODEL=Perl perl ...
		1102
		1103	=item C<PERL_ANYEVENT_PROTOCOLS>
		1104
		1105	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1106	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1107	of auto probing).
		1108
		1109	Must be set to a comma-separated list of protocols or address families,
		1110	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1111	used, and preference will be given to protocols mentioned earlier in the
		1112	list.
		1113
		1114	This variable can effectively be used for denial-of-service attacks
		1115	against local programs (e.g. when setuid), although the impact is likely
		1116	small, as the program has to handle connection errors already-
		1117
		1118	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1119	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1120	- only support IPv4, never try to resolve or contact IPv6
		1121	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1122	IPv6, but prefer IPv6 over IPv4.
		1123
		1124	=item C<PERL_ANYEVENT_EDNS0>
		1125
		1126	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1127	for DNS. This extension is generally useful to reduce DNS traffic, but
		1128	some (broken) firewalls drop such DNS packets, which is why it is off by
		1129	default.
		1130
		1131	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1132	EDNS0 in its DNS requests.
		1133
		1134	=item C<PERL_ANYEVENT_MAX_FORKS>
		1135
		1136	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1137	will create in parallel.
780		1138
781	=back	1139	=back
782		1140
783	=head1 EXAMPLE PROGRAM	1141	=head1 EXAMPLE PROGRAM
784		1142
…		…
795	poll => 'r',	1153	poll => 'r',
796	cb => sub {	1154	cb => sub {
797	warn "io event <$_[0]>\n"; # will always output <r>	1155	warn "io event <$_[0]>\n"; # will always output <r>
798	chomp (my $input = <STDIN>); # read a line	1156	chomp (my $input = <STDIN>); # read a line
799	warn "read: $input\n"; # output what has been read	1157	warn "read: $input\n"; # output what has been read
800	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1158	$cv->send if $input =~ /^q/i; # quit program if /^q/i
801	},	1159	},
802	);	1160	);
803		1161
804	my $time_watcher; # can only be used once	1162	my $time_watcher; # can only be used once
805		1163
…		…
810	});	1168	});
811	}	1169	}
812		1170
813	new_timer; # create first timer	1171	new_timer; # create first timer
814		1172
815	$cv->wait; # wait until user enters /^q/i	1173	$cv->recv; # wait until user enters /^q/i
816		1174
817	=head1 REAL-WORLD EXAMPLE	1175	=head1 REAL-WORLD EXAMPLE
818		1176
819	Consider the L<Net::FCP> module. It features (among others) the following	1177	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:	1178	API calls, which are to freenet what HTTP GET requests are to http:
…		…
870	syswrite $txn->{fh}, $txn->{request}	1228	syswrite $txn->{fh}, $txn->{request}
871	or die "connection or write error";	1229	or die "connection or write error";
872	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1230	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
873		1231
874	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1232	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:	1233	result and signals any possible waiters that the request has finished:
876		1234
877	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1235	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
878		1236
879	if (end-of-file or data complete) {	1237	if (end-of-file or data complete) {
880	$txn->{result} = $txn->{buf};	1238	$txn->{result} = $txn->{buf};
881	$txn->{finished}->broadcast;	1239	$txn->{finished}->send;
882	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1240	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
883	}	1241	}
884		1242
885	The C<result> method, finally, just waits for the finished signal (if the	1243	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	1244	request was already finished, it doesn't wait, of course, and returns the
887	data:	1245	data:
888		1246
889	$txn->{finished}->wait;	1247	$txn->{finished}->recv;
890	return $txn->{result};	1248	return $txn->{result};
891		1249
892	The actual code goes further and collects all errors (C<die>s, exceptions)	1250	The actual code goes further and collects all errors (C<die>s, exceptions)
893	that occured during request processing. The C<result> method detects	1251	that occurred during request processing. The C<result> method detects
894	whether an exception as thrown (it is stored inside the $txn object)	1252	whether an exception as thrown (it is stored inside the $txn object)
895	and just throws the exception, which means connection errors and other	1253	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	1254	problems get reported tot he code that tries to use the result, not in a
897	random callback.	1255	random callback.
898		1256
…		…
929		1287
930	my $quit = AnyEvent->condvar;	1288	my $quit = AnyEvent->condvar;
931		1289
932	$fcp->txn_client_get ($url)->cb (sub {	1290	$fcp->txn_client_get ($url)->cb (sub {
933	...	1291	...
934	$quit->broadcast;	1292	$quit->send;
935	});	1293	});
936		1294
937	$quit->wait;	1295	$quit->recv;
938		1296
939		1297
940	=head1 BENCHMARKS	1298	=head1 BENCHMARKS
941		1299
942	To give you an idea of the performance and overheads that AnyEvent adds	1300	To give you an idea of the performance and overheads that AnyEvent adds
…		…
944	of various event loops I prepared some benchmarks.	1302	of various event loops I prepared some benchmarks.
945		1303
946	=head2 BENCHMARKING ANYEVENT OVERHEAD	1304	=head2 BENCHMARKING ANYEVENT OVERHEAD
947		1305
948	Here is a benchmark of various supported event models used natively and	1306	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	1307	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,	1308	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.	1309	which it is), lets them fire exactly once and destroys them again.
952		1310
953	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	1311	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
954	distribution.	1312	distribution.
…		…
971	all watchers, to avoid adding memory overhead. That means closure creation	1329	all watchers, to avoid adding memory overhead. That means closure creation
972	and memory usage is not included in the figures.	1330	and memory usage is not included in the figures.
973		1331
974	I<invoke> is the time, in microseconds, used to invoke a simple	1332	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	1333	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	1334	invoked "watcher" times, it would C<< ->send >> a condvar once to
977	signal the end of this phase.	1335	signal the end of this phase.
978		1336
979	I<destroy> is the time, in microseconds, that it takes to destroy a single	1337	I<destroy> is the time, in microseconds, that it takes to destroy a single
980	watcher.	1338	watcher.
981		1339
…		…
1041	file descriptor is dup()ed for each watcher. This shows that the dup()	1399	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	1400	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	1401	hidden memory cost inside the kernel which is not reflected in the figures
1044	above).	1402	above).
1045		1403
1046	C<POE>, regardless of underlying event loop (whether using its pure	1404	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	1405	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	1406	be tested because it wasn't working) shows abysmal performance and
1049	and memory usage: Watchers use almost 30 times as much memory as	1407	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	1408	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	1409	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	1410	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1411	implementation.
		1412
1053	implementation. The design of the POE adaptor class in AnyEvent can not	1413	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	1414	for the performance issues, though, as session creation overhead is
1055	to execution of the state machine, which is coded pretty optimally within	1415	small compared to execution of the state machine, which is coded pretty
1056	L<AnyEvent::Impl::POE>. POE simply seems to be abysmally slow.	1416	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1417	using multiple sessions is not a good approach, especially regarding
		1418	memory usage, even the author of POE could not come up with a faster
		1419	design).
1057		1420
1058	=head3 Summary	1421	=head3 Summary
1059		1422
1060	=over 4	1423	=over 4
1061		1424
…		…
1072		1435
1073	=back	1436	=back
1074		1437
1075	=head2 BENCHMARKING THE LARGE SERVER CASE	1438	=head2 BENCHMARKING THE LARGE SERVER CASE
1076		1439
1077	This benchmark atcually benchmarks the event loop itself. It works by	1440	This benchmark actually benchmarks the event loop itself. It works by
1078	creating a number of "servers": each server consists of a socketpair, a	1441	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	1442	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	1443	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".	1444	watcher reads a byte it will write that byte to a random other "server".
1082		1445
1083	The effect is that there will be a lot of I/O watchers, only part of which	1446	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	1447	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	1448	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	1449	timeout is reset each time something is read because that reflects how
1087	most timeouts work (and puts extra pressure on the event loops).	1450	most timeouts work (and puts extra pressure on the event loops).
1088		1451
1089	In this benchmark, we use 10000 socketpairs (20000 sockets), of which 100	1452	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	1453	(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.	1454	connections, most of which are idle at any one point in time.
1092		1455
1093	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	1456	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1094	distribution.	1457	distribution.
…		…
1096	=head3 Explanation of the columns	1459	=head3 Explanation of the columns
1097		1460
1098	I<sockets> is the number of sockets, and twice the number of "servers" (as	1461	I<sockets> is the number of sockets, and twice the number of "servers" (as
1099	each server has a read and write socket end).	1462	each server has a read and write socket end).
1100		1463
1101	I<create> is the time it takes to create a socketpair (which is	1464	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.	1465	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
1103		1466
1104	I<request>, the most important value, is the time it takes to handle a	1467	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	1468	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	1469	it to another server. This includes deleting the old timeout and creating
…		…
1140		1503
1141	=head3 Summary	1504	=head3 Summary
1142		1505
1143	=over 4	1506	=over 4
1144		1507
1145	=item * The pure perl implementation performs extremely well, considering	1508	=item * The pure perl implementation performs extremely well.
1146	that it uses select.
1147		1509
1148	=item * Avoid Glib or POE in large projects where performance matters.	1510	=item * Avoid Glib or POE in large projects where performance matters.
1149		1511
1150	=back	1512	=back
1151		1513
…		…
1180	speed most when you have lots of watchers, not when you only have a few of	1542	speed most when you have lots of watchers, not when you only have a few of
1181	them).	1543	them).
1182		1544
1183	EV is again fastest.	1545	EV is again fastest.
1184		1546
1185	The C-based event loops Event and Glib come in second this time, as the	1547	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	1548	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	1549	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		1550
1192	POE also performs much better in this case, but is is still far behind the	1551	POE also performs much better in this case, but is is still far behind the
1193	others.	1552	others.
1194		1553
1195	=head3 Summary	1554	=head3 Summary
…		…
1203		1562
1204		1563
1205	=head1 FORK	1564	=head1 FORK
1206		1565
1207	Most event libraries are not fork-safe. The ones who are usually are	1566	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.	1567	because they rely on inefficient but fork-safe C<select> or C<poll>
		1568	calls. Only L<EV> is fully fork-aware.
1209		1569
1210	If you have to fork, you must either do so I<before> creating your first	1570	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.	1571	watcher OR you must not use AnyEvent at all in the child.
1212		1572
1213		1573
…		…
1225		1585
1226	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1586	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1227		1587
1228	use AnyEvent;	1588	use AnyEvent;
1229		1589
		1590	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		1591	be used to probe what backend is used and gain other information (which is
		1592	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).
		1593
1230		1594
1231	=head1 SEE ALSO	1595	=head1 SEE ALSO
1232		1596
1233	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1597	Utility functions: L<AnyEvent::Util>.
1234	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,	1598
		1599	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
1235	L<Event::Lib>, L<Qt>, L<POE>.	1600	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1236		1601
1237	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1602	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1238	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,	1603	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>,	1604	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1240	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1605	L<AnyEvent::Impl::POE>.
1241		1606
		1607	Non-blocking file handles, sockets, TCP clients and
		1608	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.
		1609
		1610	Asynchronous DNS: L<AnyEvent::DNS>.
		1611
		1612	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,
		1613
1242	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1614	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1243		1615
1244		1616
1245	=head1 AUTHOR	1617	=head1 AUTHOR
1246		1618
1247	Marc Lehmann <schmorp@schmorp.de>	1619	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 1.142 by root, Tue May 27 02:34:30 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 1.142 by root, Tue May 27 02:34:30 2008 UTC