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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.84 by root, Fri Apr 25 13:48:42 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		76
72	=head1 DESCRIPTION	77	=head1 DESCRIPTION
73		78
74	L<AnyEvent> provides an identical interface to multiple event loops. This	79	L<AnyEvent> provides an identical interface to multiple event loops. This
75	allows module authors to utilise an event loop without forcing module	80	allows module authors to utilise an event loop without forcing module
…		…
79	The interface itself is vaguely similar, but not identical to the L<Event>	84	The interface itself is vaguely similar, but not identical to the L<Event>
80	module.	85	module.
81		86
82	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
83	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
84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,	89	following modules is already loaded: L<EV>,
85	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>,
86	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
87	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
88	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
89	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
…		…
103	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
104	use AnyEvent so their modules work together with others seamlessly...	109	use AnyEvent so their modules work together with others seamlessly...
105		110
106	The pure-perl implementation of AnyEvent is called	111	The pure-perl implementation of AnyEvent is called
107	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
108	explicitly.	113	explicitly and enjoy the high availability of that event loop :)
109		114
110	=head1 WATCHERS	115	=head1 WATCHERS
111		116
112	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
113	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
114	the callback to call, the filehandle to watch, etc.	119	the callback to call, the file handle to watch, etc.
115		120
116	These watchers are normal Perl objects with normal Perl lifetime. After	121	These watchers are normal Perl objects with normal Perl lifetime. After
117	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
118	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
119	is in control).	124	is in control).
…		…
141	=head2 I/O WATCHERS	146	=head2 I/O WATCHERS
142		147
143	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	148	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
144	with the following mandatory key-value pairs as arguments:	149	with the following mandatory key-value pairs as arguments:
145		150
146	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for	151	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch
147	events. C<poll> must be a string that is either C<r> or C<w>, which	152	for events. C<poll> must be a string that is either C<r> or C<w>,
148	creates a watcher waiting for "r"eadable or "w"ritable events,	153	which creates a watcher waiting for "r"eadable or "w"ritable events,
149	respectively. C<cb> is the callback to invoke each time the file handle	154	respectively. C<cb> is the callback to invoke each time the file handle
150	becomes ready.	155	becomes ready.
		156
		157	Although the callback might get passed parameters, their value and
		158	presence is undefined and you cannot rely on them. Portable AnyEvent
		159	callbacks cannot use arguments passed to I/O watcher callbacks.
151		160
152	The I/O watcher might use the underlying file descriptor or a copy of it.	161	The I/O watcher might use the underlying file descriptor or a copy of it.
153	You must not close a file handle as long as any watcher is active on the	162	You must not close a file handle as long as any watcher is active on the
154	underlying file descriptor.	163	underlying file descriptor.
155		164
156	Some event loops issue spurious readyness notifications, so you should	165	Some event loops issue spurious readyness notifications, so you should
157	always use non-blocking calls when reading/writing from/to your file	166	always use non-blocking calls when reading/writing from/to your file
158	handles.	167	handles.
159
160	Although the callback might get passed parameters, their value and
161	presence is undefined and you cannot rely on them. Portable AnyEvent
162	callbacks cannot use arguments passed to I/O watcher callbacks.
163		168
164	Example:	169	Example:
165		170
166	# wait for readability of STDIN, then read a line and disable the watcher	171	# wait for readability of STDIN, then read a line and disable the watcher
167	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
…		…
174		179
175	You can create a time watcher by calling the C<< AnyEvent->timer >>	180	You can create a time watcher by calling the C<< AnyEvent->timer >>
176	method with the following mandatory arguments:	181	method with the following mandatory arguments:
177		182
178	C<after> specifies after how many seconds (fractional values are	183	C<after> specifies after how many seconds (fractional values are
179	supported) should the timer activate. C<cb> the callback to invoke in that	184	supported) the callback should be invoked. C<cb> is the callback to invoke
180	case.	185	in that case.
		186
		187	Although the callback might get passed parameters, their value and
		188	presence is undefined and you cannot rely on them. Portable AnyEvent
		189	callbacks cannot use arguments passed to time watcher callbacks.
181		190
182	The timer callback will be invoked at most once: if you want a repeating	191	The timer callback will be invoked at most once: if you want a repeating
183	timer you have to create a new watcher (this is a limitation by both Tk	192	timer you have to create a new watcher (this is a limitation by both Tk
184	and Glib).	193	and Glib).
185
186	Although the callback might get passed parameters, their value and
187	presence is undefined and you cannot rely on them. Portable AnyEvent
188	callbacks cannot use arguments passed to time watcher callbacks.
189		194
190	Example:	195	Example:
191		196
192	# fire an event after 7.7 seconds	197	# fire an event after 7.7 seconds
193	my $w = AnyEvent->timer (after => 7.7, cb => sub {	198	my $w = AnyEvent->timer (after => 7.7, cb => sub {
…		…
234		239
235	You can watch for signals using a signal watcher, C<signal> is the signal	240	You can watch for signals using a signal watcher, C<signal> is the signal
236	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	241	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
237	be invoked whenever a signal occurs.	242	be invoked whenever a signal occurs.
238		243
		244	Although the callback might get passed parameters, their value and
		245	presence is undefined and you cannot rely on them. Portable AnyEvent
		246	callbacks cannot use arguments passed to signal watcher callbacks.
		247
239	Multiple signal occurances can be clumped together into one callback	248	Multiple signal occurrences can be clumped together into one callback
240	invocation, and callback invocation will be synchronous. synchronous means	249	invocation, and callback invocation will be synchronous. Synchronous means
241	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,
242	but it is guarenteed not to interrupt any other callbacks.	251	but it is guaranteed not to interrupt any other callbacks.
243		252
244	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
245	between multiple watchers.	254	between multiple watchers.
246		255
247	This watcher might use C<%SIG>, so programs overwriting those signals	256	This watcher might use C<%SIG>, so programs overwriting those signals
…		…
257		266
258	The child process is specified by the C<pid> argument (if set to C<0>, it	267	The child process is specified by the C<pid> argument (if set to C<0>, it
259	watches for any child process exit). The watcher will trigger as often	268	watches for any child process exit). The watcher will trigger as often
260	as status change for the child are received. This works by installing a	269	as status change for the child are received. This works by installing a
261	signal handler for C<SIGCHLD>. The callback will be called with the pid	270	signal handler for C<SIGCHLD>. The callback will be called with the pid
262	and exit status (as returned by waitpid).	271	and exit status (as returned by waitpid), so unlike other watcher types,
		272	you I<can> rely on child watcher callback arguments.
263		273
264	There is a slight catch to child watchers, however: you usually start them	274	There is a slight catch to child watchers, however: you usually start them
265	I<after> the child process was created, and this means the process could	275	I<after> the child process was created, and this means the process could
266	have exited already (and no SIGCHLD will be sent anymore).	276	have exited already (and no SIGCHLD will be sent anymore).
267		277
…		…
274	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	284	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).
275		285
276	Example: fork a process and wait for it	286	Example: fork a process and wait for it
277		287
278	my $done = AnyEvent->condvar;	288	my $done = AnyEvent->condvar;
279
280	AnyEvent::detect; # force event module to be initialised
281		289
282	my $pid = fork or exit 5;	290	my $pid = fork or exit 5;
283		291
284	my $w = AnyEvent->child (	292	my $w = AnyEvent->child (
285	pid => $pid,	293	pid => $pid,
286	cb => sub {	294	cb => sub {
287	my ($pid, $status) = @_;	295	my ($pid, $status) = @_;
288	warn "pid $pid exited with status $status";	296	warn "pid $pid exited with status $status";
289	$done->broadcast;	297	$done->send;
290	},	298	},
291	);	299	);
292		300
293	# do something else, then wait for process exit	301	# do something else, then wait for process exit
294	$done->wait;	302	$done->recv;
295		303
296	=head2 CONDITION VARIABLES	304	=head2 CONDITION VARIABLES
297		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
298	Condition variables can be created by calling the C<< AnyEvent->condvar >>	316	Condition variables can be created by calling the C<< AnyEvent->condvar
299	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.
300		320
301	A condition variable waits for a condition - precisely that the C<<	321	After creation, the condition variable is "false" until it becomes "true"
302	->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).
303		325
304	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,
305	example, if you write a module that does asynchronous http requests,	334	for example, if you write a module that does asynchronous http requests,
306	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
307	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.
308		338
309	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,
310	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
311	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
312	->broadcast >> the "quit" event.	342	button of your app, which would C<< ->send >> the "quit" event.
313		343
314	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
315	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
316	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
317	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,
318	as this asks for trouble.	348	as this asks for trouble.
319		349
320	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.
321		391
322	=over 4	392	=over 4
323		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
324	=item $cv->wait	425	=item $cv->end
325		426
326	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 $cv->recv
		484
		485	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
327	called on c<$cv>, while servicing other watchers normally.	486	>> methods have been called on c<$cv>, while servicing other watchers
		487	normally.
328		488
329	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
330	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.
331		497
332	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
333	(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
334	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
335	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
336	condition variables with some kind of request results and supporting	502	condition variables with some kind of request results and supporting
337	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,
338	while still suppporting blocking waits if the caller so desires).	504	while still supporting blocking waits if the caller so desires).
339		505
340	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
341	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
342	multiple interpreters or coroutines/threads, none of which C<AnyEvent>	508	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
343	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and	509	can supply.
344	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
345	from different coroutines, however).
346		510
347	=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).
348		516
349	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
350	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
351	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.
352		535
353	=back	536	=back
354
355	Example:
356
357	# wait till the result is ready
358	my $result_ready = AnyEvent->condvar;
359
360	# do something such as adding a timer
361	# or socket watcher the calls $result_ready->broadcast
362	# when the "result" is ready.
363	# in this case, we simply use a timer:
364	my $w = AnyEvent->timer (
365	after => 1,
366	cb => sub { $result_ready->broadcast },
367	);
368
369	# this "blocks" (while handling events) till the watcher
370	# calls broadcast
371	$result_ready->wait;
372		537
373	=head1 GLOBAL VARIABLES AND FUNCTIONS	538	=head1 GLOBAL VARIABLES AND FUNCTIONS
374		539
375	=over 4	540	=over 4
376		541
…		…
382	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	547	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
383	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	548	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
384		549
385	The known classes so far are:	550	The known classes so far are:
386		551
387	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
388	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
389	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).	552	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
390	AnyEvent::Impl::Event based on Event, second best choice.	553	AnyEvent::Impl::Event based on Event, second best choice.
		554	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
391	AnyEvent::Impl::Glib based on Glib, third-best choice.	555	AnyEvent::Impl::Glib based on Glib, third-best choice.
392	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
393	AnyEvent::Impl::Tk based on Tk, very bad choice.	556	AnyEvent::Impl::Tk based on Tk, very bad choice.
394	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	557	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
395	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	558	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
396	AnyEvent::Impl::POE based on POE, not generic enough for full support.	559	AnyEvent::Impl::POE based on POE, not generic enough for full support.
397		560
…		…
410	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	573	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
411	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
412	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
413	runtime.	576	runtime.
414		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
415	=back	599	=back
416		600
417	=head1 WHAT TO DO IN A MODULE	601	=head1 WHAT TO DO IN A MODULE
418		602
419	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
…		…
422	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
423	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
424	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
425	to load the event module first.	609	to load the event module first.
426		610
427	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
428	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
429	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
430	events is to stay interactive.	614	events is to stay interactive.
431		615
432	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
433	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
434	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 >>
435	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).
436		620
437	=head1 WHAT TO DO IN THE MAIN PROGRAM	621	=head1 WHAT TO DO IN THE MAIN PROGRAM
438		622
439	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
…		…
441		625
442	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
443	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
444	decide which implementation to chose if some module relies on it.	628	decide which implementation to chose if some module relies on it.
445		629
446	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
447	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
448	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
449	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
450	modules might create watchers when they are loaded, and AnyEvent will	634	modules might create watchers when they are loaded, and AnyEvent will
451	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
452	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.
453		637
454	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
455	loading the C<AnyEvent::Impl::Perl> module, which gives you similar	639	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
456	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
		658
		659	=head1 OTHER MODULES
		660
		661	The following is a non-exhaustive list of additional modules that use
		662	AnyEvent and can therefore be mixed easily with other AnyEvent modules
		663	in the same program. Some of the modules come with AnyEvent, some are
		664	available via CPAN.
		665
		666	=over 4
		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
		691	=item L<AnyEvent::FastPing>
		692
		693	The fastest ping in the west.
		694
		695	=item L<Net::IRC3>
		696
		697	AnyEvent based IRC client module family.
		698
		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.
		730
		731	=back
457		732
458	=cut	733	=cut
459		734
460	package AnyEvent;	735	package AnyEvent;
461		736
462	no warnings;	737	no warnings;
463	use strict;	738	use strict;
464		739
465	use Carp;	740	use Carp;
466		741
467	our $VERSION = '3.3';	742	our $VERSION = '4.05';
468	our $MODEL;	743	our $MODEL;
469		744
470	our $AUTOLOAD;	745	our $AUTOLOAD;
471	our @ISA;	746	our @ISA;
472		747
		748	our @REGISTRY;
		749
		750	our $WIN32;
		751
		752	BEGIN {
		753	my $win32 = ! ! ($^O =~ /mswin32/i);
		754	eval "sub WIN32(){ $win32 }";
		755	}
		756
473	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	757	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
474		758
475	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	$ENV{PERL_ANYEVENT_PROTOCOLS} \|\| "ipv4,ipv6";
		766	}
476		767
477	my @models = (	768	my @models = (
478	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
479	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
480	[EV:: => AnyEvent::Impl::EV::],	769	[EV:: => AnyEvent::Impl::EV::],
481	[Event:: => AnyEvent::Impl::Event::],	770	[Event:: => AnyEvent::Impl::Event::],
482	[Glib:: => AnyEvent::Impl::Glib::],
483	[Tk:: => AnyEvent::Impl::Tk::],
484	[Wx:: => AnyEvent::Impl::POE::],
485	[Prima:: => AnyEvent::Impl::POE::],
486	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	771	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
487	# everything below here will not be autoprobed as the pureperl backend should work everywhere	772	# everything below here will not be autoprobed
		773	# as the pureperl backend should work everywhere
		774	# and is usually faster
		775	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		776	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
488	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	777	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
489	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	778	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
490	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	779	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		780	[Wx:: => AnyEvent::Impl::POE::],
		781	[Prima:: => AnyEvent::Impl::POE::],
491	);	782	);
492		783
493	our %method = map +($_ => 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	}
494		807
495	sub detect() {	808	sub detect() {
496	unless ($MODEL) {	809	unless ($MODEL) {
497	no strict 'refs';	810	no strict 'refs';
		811	local $SIG{__DIE__};
498		812
499	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	813	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
500	my $model = "AnyEvent::Impl::$1";	814	my $model = "AnyEvent::Impl::$1";
501	if (eval "require $model") {	815	if (eval "require $model") {
502	$MODEL = $model;	816	$MODEL = $model;
…		…
532	last;	846	last;
533	}	847	}
534	}	848	}
535		849
536	$MODEL	850	$MODEL
537	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.";
538	}	852	}
539	}	853	}
540		854
541	unshift @ISA, $MODEL;	855	unshift @ISA, $MODEL;
542	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	856	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		857
		858	(shift @post_detect)->() while @post_detect;
543	}	859	}
544		860
545	$MODEL	861	$MODEL
546	}	862	}
547		863
…		…
557	$class->$func (@_);	873	$class->$func (@_);
558	}	874	}
559		875
560	package AnyEvent::Base;	876	package AnyEvent::Base;
561		877
562	# default implementation for ->condvar, ->wait, ->broadcast	878	# default implementation for ->condvar
563		879
564	sub condvar {	880	sub condvar {
565	bless \my $flag, "AnyEvent::Base::CondVar"	881	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::
566	}
567
568	sub AnyEvent::Base::CondVar::broadcast {
569	${$_[0]}++;
570	}
571
572	sub AnyEvent::Base::CondVar::wait {
573	AnyEvent->one_event while !${$_[0]};
574	}	882	}
575		883
576	# default implementation for ->signal	884	# default implementation for ->signal
577		885
578	our %SIG_CB;	886	our %SIG_CB;
…		…
631	or Carp::croak "required option 'pid' is missing";	939	or Carp::croak "required option 'pid' is missing";
632		940
633	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	941	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
634		942
635	unless ($WNOHANG) {	943	unless ($WNOHANG) {
636	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;	944	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
637	}	945	}
638		946
639	unless ($CHLD_W) {	947	unless ($CHLD_W) {
640	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	948	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
641	# 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
…		…
651	delete $PID_CB{$pid}{$cb};	959	delete $PID_CB{$pid}{$cb};
652	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	960	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
653		961
654	undef $CHLD_W unless keys %PID_CB;	962	undef $CHLD_W unless keys %PID_CB;
655	}	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;
656		1024
657	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1025	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
658		1026
659	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
660	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
…		…
717	model it chooses.	1085	model it chooses.
718		1086
719	=item C<PERL_ANYEVENT_MODEL>	1087	=item C<PERL_ANYEVENT_MODEL>
720		1088
721	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
722	autodetection and -probing kicks in. It must be a string consisting	1090	auto detection and -probing kicks in. It must be a string consisting
723	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended	1091	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
724	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,
725	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
726	autodetection and -probing.	1094	auto detection and -probing.
727		1095
728	This functionality might change in future versions.	1096	This functionality might change in future versions.
729		1097
730	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
731	could start your program like this:	1099	could start your program like this:
732		1100
733	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.
734		1138
735	=back	1139	=back
736		1140
737	=head1 EXAMPLE PROGRAM	1141	=head1 EXAMPLE PROGRAM
738		1142
…		…
749	poll => 'r',	1153	poll => 'r',
750	cb => sub {	1154	cb => sub {
751	warn "io event <$_[0]>\n"; # will always output <r>	1155	warn "io event <$_[0]>\n"; # will always output <r>
752	chomp (my $input = <STDIN>); # read a line	1156	chomp (my $input = <STDIN>); # read a line
753	warn "read: $input\n"; # output what has been read	1157	warn "read: $input\n"; # output what has been read
754	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1158	$cv->send if $input =~ /^q/i; # quit program if /^q/i
755	},	1159	},
756	);	1160	);
757		1161
758	my $time_watcher; # can only be used once	1162	my $time_watcher; # can only be used once
759		1163
…		…
764	});	1168	});
765	}	1169	}
766		1170
767	new_timer; # create first timer	1171	new_timer; # create first timer
768		1172
769	$cv->wait; # wait until user enters /^q/i	1173	$cv->recv; # wait until user enters /^q/i
770		1174
771	=head1 REAL-WORLD EXAMPLE	1175	=head1 REAL-WORLD EXAMPLE
772		1176
773	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
774	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:
…		…
824	syswrite $txn->{fh}, $txn->{request}	1228	syswrite $txn->{fh}, $txn->{request}
825	or die "connection or write error";	1229	or die "connection or write error";
826	$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 });
827		1231
828	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
829	result and signals any possible waiters that the request ahs finished:	1233	result and signals any possible waiters that the request has finished:
830		1234
831	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1235	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
832		1236
833	if (end-of-file or data complete) {	1237	if (end-of-file or data complete) {
834	$txn->{result} = $txn->{buf};	1238	$txn->{result} = $txn->{buf};
835	$txn->{finished}->broadcast;	1239	$txn->{finished}->send;
836	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1240	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
837	}	1241	}
838		1242
839	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
840	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
841	data:	1245	data:
842		1246
843	$txn->{finished}->wait;	1247	$txn->{finished}->recv;
844	return $txn->{result};	1248	return $txn->{result};
845		1249
846	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)
847	that occured during request processing. The C<result> method detects	1251	that occurred during request processing. The C<result> method detects
848	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)
849	and just throws the exception, which means connection errors and other	1253	and just throws the exception, which means connection errors and other
850	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
851	random callback.	1255	random callback.
852		1256
…		…
883		1287
884	my $quit = AnyEvent->condvar;	1288	my $quit = AnyEvent->condvar;
885		1289
886	$fcp->txn_client_get ($url)->cb (sub {	1290	$fcp->txn_client_get ($url)->cb (sub {
887	...	1291	...
888	$quit->broadcast;	1292	$quit->send;
889	});	1293	});
890		1294
891	$quit->wait;	1295	$quit->recv;
892		1296
893		1297
894	=head1 BENCHMARK	1298	=head1 BENCHMARKS
895		1299
896	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
897	over the event loops themselves (and to give you an impression of the	1301	over the event loops themselves and to give you an impression of the speed
898	speed of various event loops), here is a benchmark of various supported	1302	of various event loops I prepared some benchmarks.
899	event models natively and with anyevent. The benchmark creates a lot of	1303
900	timers (with a zero timeout) and I/O watchers (watching STDOUT, a pty, to	1304	=head2 BENCHMARKING ANYEVENT OVERHEAD
		1305
		1306	Here is a benchmark of various supported event models used natively and
		1307	through AnyEvent. The benchmark creates a lot of timers (with a zero
		1308	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
901	become writable, which it is), lets them fire exactly once and destroys	1309	which it is), lets them fire exactly once and destroys them again.
902	them again.
903		1310
904	Rewriting the benchmark to use many different sockets instead of using	1311	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
905	the same filehandle for all I/O watchers results in a much longer runtime	1312	distribution.
906	(socket creation is expensive), but qualitatively the same figures, so it
907	was not used.
908		1313
909	=head2 Explanation of the columns	1314	=head3 Explanation of the columns
910		1315
911	I<watcher> is the number of event watchers created/destroyed. Since	1316	I<watcher> is the number of event watchers created/destroyed. Since
912	different event models feature vastly different performances, each event	1317	different event models feature vastly different performances, each event
913	loop was given a number of watchers so that overall runtime is acceptable	1318	loop was given a number of watchers so that overall runtime is acceptable
914	and similar between tested event loop (and keep them from crashing): Glib	1319	and similar between tested event loop (and keep them from crashing): Glib
…		…
924	all watchers, to avoid adding memory overhead. That means closure creation	1329	all watchers, to avoid adding memory overhead. That means closure creation
925	and memory usage is not included in the figures.	1330	and memory usage is not included in the figures.
926		1331
927	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
928	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
929	invoked "watcher" times, it would C<< ->broadcast >> a condvar once to	1334	invoked "watcher" times, it would C<< ->send >> a condvar once to
930	signal the end of this phase.	1335	signal the end of this phase.
931		1336
932	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
933	watcher.	1338	watcher.
934		1339
935	=head2 Results	1340	=head3 Results
936		1341
937	name watchers bytes create invoke destroy comment	1342	name watchers bytes create invoke destroy comment
938	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1343	EV/EV 400000 244 0.56 0.46 0.31 EV native interface
939	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1344	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers
940	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1345	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal
941	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1346	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation
942	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1347	Event/Event 16000 516 31.88 31.30 0.85 Event native interface
943	Event/Any 16000 936 39.17 33.63 1.43 Event + AnyEvent watchers	1348	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers
944	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1349	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour
945	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1350	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers
946	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1351	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event
947	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1352	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select
948		1353
949	=head2 Discussion	1354	=head3 Discussion
950		1355
951	The benchmark does I<not> measure scalability of the event loop very	1356	The benchmark does I<not> measure scalability of the event loop very
952	well. For example, a select-based event loop (such as the pure perl one)	1357	well. For example, a select-based event loop (such as the pure perl one)
953	can never compete with an event loop that uses epoll when the number of	1358	can never compete with an event loop that uses epoll when the number of
954	file descriptors grows high. In this benchmark, all events become ready at	1359	file descriptors grows high. In this benchmark, all events become ready at
955	the same time, so select/poll-based implementations get an unnatural speed	1360	the same time, so select/poll-based implementations get an unnatural speed
956	boost.	1361	boost.
957		1362
		1363	Also, note that the number of watchers usually has a nonlinear effect on
		1364	overall speed, that is, creating twice as many watchers doesn't take twice
		1365	the time - usually it takes longer. This puts event loops tested with a
		1366	higher number of watchers at a disadvantage.
		1367
		1368	To put the range of results into perspective, consider that on the
		1369	benchmark machine, handling an event takes roughly 1600 CPU cycles with
		1370	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
		1371	cycles with POE.
		1372
958	C<EV> is the sole leader regarding speed and memory use, which are both	1373	C<EV> is the sole leader regarding speed and memory use, which are both
959	maximal/minimal, respectively. Even when going through AnyEvent, it uses	1374	maximal/minimal, respectively. Even when going through AnyEvent, it uses
960	far less memory than any other event loop and is still faster than Event	1375	far less memory than any other event loop and is still faster than Event
961	natively.	1376	natively.
962		1377
963	The pure perl implementation is hit in a few sweet spots (both the	1378	The pure perl implementation is hit in a few sweet spots (both the
964	zero timeout and the use of a single fd hit optimisations in the perl	1379	constant timeout and the use of a single fd hit optimisations in the perl
965	interpreter and the backend itself, and all watchers become ready at the	1380	interpreter and the backend itself). Nevertheless this shows that it
966	same time). Nevertheless this shows that it adds very little overhead in	1381	adds very little overhead in itself. Like any select-based backend its
967	itself. Like any select-based backend its performance becomes really bad	1382	performance becomes really bad with lots of file descriptors (and few of
968	with lots of file descriptors (and few of them active), of course, but	1383	them active), of course, but this was not subject of this benchmark.
969	this was not subject of this benchmark.
970		1384
971	The C<Event> module has a relatively high setup and callback invocation cost,	1385	The C<Event> module has a relatively high setup and callback invocation
972	but overall scores on the third place.	1386	cost, but overall scores in on the third place.
973		1387
974	C<Glib>'s memory usage is quite a bit bit higher, but it features a	1388	C<Glib>'s memory usage is quite a bit higher, but it features a
975	faster callback invocation and overall ends up in the same class as	1389	faster callback invocation and overall ends up in the same class as
976	C<Event>. However, Glib scales extremely badly, doubling the number of	1390	C<Event>. However, Glib scales extremely badly, doubling the number of
977	watchers increases the processing time by more than a factor of four,	1391	watchers increases the processing time by more than a factor of four,
978	making it completely unusable when using larger numbers of watchers	1392	making it completely unusable when using larger numbers of watchers
979	(note that only a single file descriptor was used in the benchmark, so	1393	(note that only a single file descriptor was used in the benchmark, so
…		…
982	The C<Tk> adaptor works relatively well. The fact that it crashes with	1396	The C<Tk> adaptor works relatively well. The fact that it crashes with
983	more than 2000 watchers is a big setback, however, as correctness takes	1397	more than 2000 watchers is a big setback, however, as correctness takes
984	precedence over speed. Nevertheless, its performance is surprising, as the	1398	precedence over speed. Nevertheless, its performance is surprising, as the
985	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()
986	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
987	hidden memory cost inside the kernel, though, that is not reflected in the	1401	hidden memory cost inside the kernel which is not reflected in the figures
988	figures above).	1402	above).
989		1403
990	C<POE>, regardless of underlying event loop (wether using its pure perl	1404	C<POE>, regardless of underlying event loop (whether using its pure perl
991	select-based backend or the Event module) shows abysmal performance and	1405	select-based backend or the Event module, the POE-EV backend couldn't
		1406	be tested because it wasn't working) shows abysmal performance and
992	memory usage: Watchers use almost 30 times as much memory as EV watchers,	1407	memory usage with AnyEvent: Watchers use almost 30 times as much memory
993	and 10 times as much memory as both Event or EV via AnyEvent. Watcher	1408	as EV watchers, and 10 times as much memory as Event (the high memory
		1409	requirements are caused by requiring a session for each watcher). Watcher
994	invocation 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
995	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
996	really account for this, as session creation overhead is small compared	1414	for the performance issues, though, as session creation overhead is
997	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
998	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).
999		1420
1000	=head2 Summary	1421	=head3 Summary
1001		1422
		1423	=over 4
		1424
1002	Using EV through AnyEvent is faster than any other event loop, but most	1425	=item * Using EV through AnyEvent is faster than any other event loop
1003	event loops have acceptable performance with or without AnyEvent.	1426	(even when used without AnyEvent), but most event loops have acceptable
		1427	performance with or without AnyEvent.
1004		1428
1005	The overhead AnyEvent adds is usually much smaller than the overhead of	1429	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
1006	the actual event loop, only with extremely fast event loops such as the EV	1430	the actual event loop, only with extremely fast event loops such as EV
1007	adds AnyEvent significant overhead.	1431	adds AnyEvent significant overhead.
1008		1432
1009	And you should simply avoid POE like the plague if you want performance or	1433	=item * You should avoid POE like the plague if you want performance or
1010	reasonable memory usage.	1434	reasonable memory usage.
1011		1435
		1436	=back
		1437
		1438	=head2 BENCHMARKING THE LARGE SERVER CASE
		1439
		1440	This benchmark actually benchmarks the event loop itself. It works by
		1441	creating a number of "servers": each server consists of a socket pair, a
		1442	timeout watcher that gets reset on activity (but never fires), and an I/O
		1443	watcher waiting for input on one side of the socket. Each time the socket
		1444	watcher reads a byte it will write that byte to a random other "server".
		1445
		1446	The effect is that there will be a lot of I/O watchers, only part of which
		1447	are active at any one point (so there is a constant number of active
		1448	fds for each loop iteration, but which fds these are is random). The
		1449	timeout is reset each time something is read because that reflects how
		1450	most timeouts work (and puts extra pressure on the event loops).
		1451
		1452	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
		1453	(1%) are active. This mirrors the activity of large servers with many
		1454	connections, most of which are idle at any one point in time.
		1455
		1456	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
		1457	distribution.
		1458
		1459	=head3 Explanation of the columns
		1460
		1461	I<sockets> is the number of sockets, and twice the number of "servers" (as
		1462	each server has a read and write socket end).
		1463
		1464	I<create> is the time it takes to create a socket pair (which is
		1465	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
		1466
		1467	I<request>, the most important value, is the time it takes to handle a
		1468	single "request", that is, reading the token from the pipe and forwarding
		1469	it to another server. This includes deleting the old timeout and creating
		1470	a new one that moves the timeout into the future.
		1471
		1472	=head3 Results
		1473
		1474	name sockets create request
		1475	EV 20000 69.01 11.16
		1476	Perl 20000 73.32 35.87
		1477	Event 20000 212.62 257.32
		1478	Glib 20000 651.16 1896.30
		1479	POE 20000 349.67 12317.24 uses POE::Loop::Event
		1480
		1481	=head3 Discussion
		1482
		1483	This benchmark I<does> measure scalability and overall performance of the
		1484	particular event loop.
		1485
		1486	EV is again fastest. Since it is using epoll on my system, the setup time
		1487	is relatively high, though.
		1488
		1489	Perl surprisingly comes second. It is much faster than the C-based event
		1490	loops Event and Glib.
		1491
		1492	Event suffers from high setup time as well (look at its code and you will
		1493	understand why). Callback invocation also has a high overhead compared to
		1494	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
		1495	uses select or poll in basically all documented configurations.
		1496
		1497	Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It
		1498	clearly fails to perform with many filehandles or in busy servers.
		1499
		1500	POE is still completely out of the picture, taking over 1000 times as long
		1501	as EV, and over 100 times as long as the Perl implementation, even though
		1502	it uses a C-based event loop in this case.
		1503
		1504	=head3 Summary
		1505
		1506	=over 4
		1507
		1508	=item * The pure perl implementation performs extremely well.
		1509
		1510	=item * Avoid Glib or POE in large projects where performance matters.
		1511
		1512	=back
		1513
		1514	=head2 BENCHMARKING SMALL SERVERS
		1515
		1516	While event loops should scale (and select-based ones do not...) even to
		1517	large servers, most programs we (or I :) actually write have only a few
		1518	I/O watchers.
		1519
		1520	In this benchmark, I use the same benchmark program as in the large server
		1521	case, but it uses only eight "servers", of which three are active at any
		1522	one time. This should reflect performance for a small server relatively
		1523	well.
		1524
		1525	The columns are identical to the previous table.
		1526
		1527	=head3 Results
		1528
		1529	name sockets create request
		1530	EV 16 20.00 6.54
		1531	Perl 16 25.75 12.62
		1532	Event 16 81.27 35.86
		1533	Glib 16 32.63 15.48
		1534	POE 16 261.87 276.28 uses POE::Loop::Event
		1535
		1536	=head3 Discussion
		1537
		1538	The benchmark tries to test the performance of a typical small
		1539	server. While knowing how various event loops perform is interesting, keep
		1540	in mind that their overhead in this case is usually not as important, due
		1541	to the small absolute number of watchers (that is, you need efficiency and
		1542	speed most when you have lots of watchers, not when you only have a few of
		1543	them).
		1544
		1545	EV is again fastest.
		1546
		1547	Perl again comes second. It is noticeably faster than the C-based event
		1548	loops Event and Glib, although the difference is too small to really
		1549	matter.
		1550
		1551	POE also performs much better in this case, but is is still far behind the
		1552	others.
		1553
		1554	=head3 Summary
		1555
		1556	=over 4
		1557
		1558	=item * C-based event loops perform very well with small number of
		1559	watchers, as the management overhead dominates.
		1560
		1561	=back
		1562
1012		1563
1013	=head1 FORK	1564	=head1 FORK
1014		1565
1015	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
1016	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.
1017		1569
1018	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
1019	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.
1020		1572
1021		1573
…		…
1033		1585
1034	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	1586	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1035		1587
1036	use AnyEvent;	1588	use AnyEvent;
1037		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
1038		1594
1039	=head1 SEE ALSO	1595	=head1 SEE ALSO
1040		1596
1041	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,	1597	Utility functions: L<AnyEvent::Util>.
1042	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>,
1043	L<Event::Lib>, L<Qt>, L<POE>.	1600	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1044		1601
1045	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,	1602	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1046	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>,
1047	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,	1604	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1048	L<AnyEvent::Impl::Qt>, L<AnyEvent::Impl::POE>.	1605	L<AnyEvent::Impl::POE>.
1049		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
1050	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.	1614	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.
1051		1615
1052		1616
1053	=head1 AUTHOR	1617	=head1 AUTHOR
1054		1618
1055	Marc Lehmann <schmorp@schmorp.de>	1619	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.84 by root, Fri Apr 25 13:48:42 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 1.84 by root, Fri Apr 25 13:48:42 2008 UTC vs.
Revision 1.142 by root, Tue May 27 02:34:30 2008 UTC