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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.170 by root, Wed Jul 9 11:53:40 2008 UTC vs.
Revision 1.233 by root, Thu Jul 9 01:22:50 2009 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, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
22		39
23	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
24		41
25	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
128	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
129	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
130	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
131	is in control).	148	is in control).
132		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
133	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
134	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
135	to it).	158	to it).
136		159
137	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
153	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
154		177
155	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
156	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
157		180
158	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	181	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
159	(AnyEvent might or might not keep a reference to this file handle). C<poll>	182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
160	must be a string that is either C<r> or C<w>, which creates a watcher	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
161	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
162	callback to invoke each time the file handle becomes ready.	191	C<cb> is the callback to invoke each time the file handle becomes ready.
163		192
164	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
165	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
166	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
167		196
…		…
299	In either case, if you care (and in most cases, you don't), then you	328	In either case, if you care (and in most cases, you don't), then you
300	can get whatever behaviour you want with any event loop, by taking the	329	can get whatever behaviour you want with any event loop, by taking the
301	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
302	account.	331	account.
303		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
304	=back	348	=back
305		349
306	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
307		351
308	You can watch for signals using a signal watcher, C<signal> is the signal	352	You can watch for signals using a signal watcher, C<signal> is the signal
…		…
331	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
332		376
333	You can also watch on a child process exit and catch its exit status.	377	You can also watch on a child process exit and catch its exit status.
334		378
335	The child process is specified by the C<pid> argument (if set to C<0>, it	379	The child process is specified by the C<pid> argument (if set to C<0>, it
336	watches for any child process exit). The watcher will trigger as often	380	watches for any child process exit). The watcher will triggered only when
337	as status change for the child are received. This works by installing a	381	the child process has finished and an exit status is available, not on
338	signal handler for C<SIGCHLD>. The callback will be called with the pid	382	any trace events (stopped/continued).
339	and exit status (as returned by waitpid), so unlike other watcher types,	383
340	you I<can> rely on child watcher callback arguments.	384	The callback will be called with the pid and exit status (as returned by
		385	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		386	callback arguments.
		387
		388	This watcher type works by installing a signal handler for C<SIGCHLD>,
		389	and since it cannot be shared, nothing else should use SIGCHLD or reap
		390	random child processes (waiting for specific child processes, e.g. inside
		391	C<system>, is just fine).
341		392
342	There is a slight catch to child watchers, however: you usually start them	393	There is a slight catch to child watchers, however: you usually start them
343	I<after> the child process was created, and this means the process could	394	I<after> the child process was created, and this means the process could
344	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
345		396
346	Not all event models handle this correctly (POE doesn't), but even for	397	Not all event models handle this correctly (neither POE nor IO::Async do,
		398	see their AnyEvent::Impl manpages for details), but even for event models
347	event models that I<do> handle this correctly, they usually need to be	399	that I<do> handle this correctly, they usually need to be loaded before
348	loaded before the process exits (i.e. before you fork in the first place).	400	the process exits (i.e. before you fork in the first place). AnyEvent's
		401	pure perl event loop handles all cases correctly regardless of when you
		402	start the watcher.
349		403
350	This means you cannot create a child watcher as the very first thing in an	404	This means you cannot create a child watcher as the very first
351	AnyEvent program, you I<have> to create at least one watcher before you	405	thing in an AnyEvent program, you I<have> to create at least one
352	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	406	watcher before you C<fork> the child (alternatively, you can call
		407	C<AnyEvent::detect>).
353		408
354	Example: fork a process and wait for it	409	Example: fork a process and wait for it
355		410
356	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
357		412
…		…
367	);	422	);
368		423
369	# do something else, then wait for process exit	424	# do something else, then wait for process exit
370	$done->recv;	425	$done->recv;
371		426
		427	=head2 IDLE WATCHERS
		428
		429	Sometimes there is a need to do something, but it is not so important
		430	to do it instantly, but only when there is nothing better to do. This
		431	"nothing better to do" is usually defined to be "no other events need
		432	attention by the event loop".
		433
		434	Idle watchers ideally get invoked when the event loop has nothing
		435	better to do, just before it would block the process to wait for new
		436	events. Instead of blocking, the idle watcher is invoked.
		437
		438	Most event loops unfortunately do not really support idle watchers (only
		439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		440	will simply call the callback "from time to time".
		441
		442	Example: read lines from STDIN, but only process them when the
		443	program is otherwise idle:
		444
		445	my @lines; # read data
		446	my $idle_w;
		447	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		448	push @lines, scalar <STDIN>;
		449
		450	# start an idle watcher, if not already done
		451	$idle_w \|\|= AnyEvent->idle (cb => sub {
		452	# handle only one line, when there are lines left
		453	if (my $line = shift @lines) {
		454	print "handled when idle: $line";
		455	} else {
		456	# otherwise disable the idle watcher again
		457	undef $idle_w;
		458	}
		459	});
		460	});
		461
372	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
373		463
374	If you are familiar with some event loops you will know that all of them	464	If you are familiar with some event loops you will know that all of them
375	require you to run some blocking "loop", "run" or similar function that	465	require you to run some blocking "loop", "run" or similar function that
376	will actively watch for new events and call your callbacks.	466	will actively watch for new events and call your callbacks.
…		…
381	The instrument to do that is called a "condition variable", so called	471	The instrument to do that is called a "condition variable", so called
382	because they represent a condition that must become true.	472	because they represent a condition that must become true.
383		473
384	Condition variables can be created by calling the C<< AnyEvent->condvar	474	Condition variables can be created by calling the C<< AnyEvent->condvar
385	>> method, usually without arguments. The only argument pair allowed is	475	>> method, usually without arguments. The only argument pair allowed is
		476
386	C<cb>, which specifies a callback to be called when the condition variable	477	C<cb>, which specifies a callback to be called when the condition variable
387	becomes true.	478	becomes true, with the condition variable as the first argument (but not
		479	the results).
388		480
389	After creation, the condition variable is "false" until it becomes "true"	481	After creation, the condition variable is "false" until it becomes "true"
390	by calling the C<send> method (or calling the condition variable as if it	482	by calling the C<send> method (or calling the condition variable as if it
391	were a callback, read about the caveats in the description for the C<<	483	were a callback, read about the caveats in the description for the C<<
392	->send >> method).	484	->send >> method).
…		…
448		540
449	my $done = AnyEvent->condvar;	541	my $done = AnyEvent->condvar;
450	my $delay = AnyEvent->timer (after => 5, cb => $done);	542	my $delay = AnyEvent->timer (after => 5, cb => $done);
451	$done->recv;	543	$done->recv;
452		544
		545	Example: Imagine an API that returns a condvar and doesn't support
		546	callbacks. This is how you make a synchronous call, for example from
		547	the main program:
		548
		549	use AnyEvent::CouchDB;
		550
		551	...
		552
		553	my @info = $couchdb->info->recv;
		554
		555	And this is how you would just ste a callback to be called whenever the
		556	results are available:
		557
		558	$couchdb->info->cb (sub {
		559	my @info = $_[0]->recv;
		560	});
		561
453	=head3 METHODS FOR PRODUCERS	562	=head3 METHODS FOR PRODUCERS
454		563
455	These methods should only be used by the producing side, i.e. the	564	These methods should only be used by the producing side, i.e. the
456	code/module that eventually sends the signal. Note that it is also	565	code/module that eventually sends the signal. Note that it is also
457	the producer side which creates the condvar in most cases, but it isn't	566	the producer side which creates the condvar in most cases, but it isn't
…		…
490		599
491	=item $cv->begin ([group callback])	600	=item $cv->begin ([group callback])
492		601
493	=item $cv->end	602	=item $cv->end
494		603
495	These two methods are EXPERIMENTAL and MIGHT CHANGE.
496
497	These two methods can be used to combine many transactions/events into	604	These two methods can be used to combine many transactions/events into
498	one. For example, a function that pings many hosts in parallel might want	605	one. For example, a function that pings many hosts in parallel might want
499	to use a condition variable for the whole process.	606	to use a condition variable for the whole process.
500		607
501	Every call to C<< ->begin >> will increment a counter, and every call to	608	Every call to C<< ->begin >> will increment a counter, and every call to
502	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	609	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
503	>>, the (last) callback passed to C<begin> will be executed. That callback	610	>>, the (last) callback passed to C<begin> will be executed. That callback
504	is I<supposed> to call C<< ->send >>, but that is not required. If no	611	is I<supposed> to call C<< ->send >>, but that is not required. If no
505	callback was set, C<send> will be called without any arguments.	612	callback was set, C<send> will be called without any arguments.
506		613
507	Let's clarify this with the ping example:	614	You can think of C<< $cv->send >> giving you an OR condition (one call
		615	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		616	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		617
		618	Let's start with a simple example: you have two I/O watchers (for example,
		619	STDOUT and STDERR for a program), and you want to wait for both streams to
		620	close before activating a condvar:
		621
		622	my $cv = AnyEvent->condvar;
		623
		624	$cv->begin; # first watcher
		625	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		626	defined sysread $fh1, my $buf, 4096
		627	or $cv->end;
		628	});
		629
		630	$cv->begin; # second watcher
		631	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		632	defined sysread $fh2, my $buf, 4096
		633	or $cv->end;
		634	});
		635
		636	$cv->recv;
		637
		638	This works because for every event source (EOF on file handle), there is
		639	one call to C<begin>, so the condvar waits for all calls to C<end> before
		640	sending.
		641
		642	The ping example mentioned above is slightly more complicated, as the
		643	there are results to be passwd back, and the number of tasks that are
		644	begung can potentially be zero:
508		645
509	my $cv = AnyEvent->condvar;	646	my $cv = AnyEvent->condvar;
510		647
511	my %result;	648	my %result;
512	$cv->begin (sub { $cv->send (\%result) });	649	$cv->begin (sub { $cv->send (\%result) });
…		…
532	loop, which serves two important purposes: first, it sets the callback	669	loop, which serves two important purposes: first, it sets the callback
533	to be called once the counter reaches C<0>, and second, it ensures that	670	to be called once the counter reaches C<0>, and second, it ensures that
534	C<send> is called even when C<no> hosts are being pinged (the loop	671	C<send> is called even when C<no> hosts are being pinged (the loop
535	doesn't execute once).	672	doesn't execute once).
536		673
537	This is the general pattern when you "fan out" into multiple subrequests:	674	This is the general pattern when you "fan out" into multiple (but
538	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	675	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
539	is called at least once, and then, for each subrequest you start, call	676	the callback and ensure C<end> is called at least once, and then, for each
540	C<begin> and for each subrequest you finish, call C<end>.	677	subrequest you start, call C<begin> and for each subrequest you finish,
		678	call C<end>.
541		679
542	=back	680	=back
543		681
544	=head3 METHODS FOR CONSUMERS	682	=head3 METHODS FOR CONSUMERS
545		683
…		…
590	=item $bool = $cv->ready	728	=item $bool = $cv->ready
591		729
592	Returns true when the condition is "true", i.e. whether C<send> or	730	Returns true when the condition is "true", i.e. whether C<send> or
593	C<croak> have been called.	731	C<croak> have been called.
594		732
595	=item $cb = $cv->cb ([new callback])	733	=item $cb = $cv->cb ($cb->($cv))
596		734
597	This is a mutator function that returns the callback set and optionally	735	This is a mutator function that returns the callback set and optionally
598	replaces it before doing so.	736	replaces it before doing so.
599		737
600	The callback will be called when the condition becomes "true", i.e. when	738	The callback will be called when the condition becomes "true", i.e. when
…		…
602	variable itself. Calling C<recv> inside the callback or at any later time	740	variable itself. Calling C<recv> inside the callback or at any later time
603	is guaranteed not to block.	741	is guaranteed not to block.
604		742
605	=back	743	=back
606		744
		745	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		746
		747	The available backend classes are (every class has its own manpage):
		748
		749	=over 4
		750
		751	=item Backends that are autoprobed when no other event loop can be found.
		752
		753	EV is the preferred backend when no other event loop seems to be in
		754	use. If EV is not installed, then AnyEvent will try Event, and, failing
		755	that, will fall back to its own pure-perl implementation, which is
		756	available everywhere as it comes with AnyEvent itself.
		757
		758	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		759	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		760	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		761
		762	=item Backends that are transparently being picked up when they are used.
		763
		764	These will be used when they are currently loaded when the first watcher
		765	is created, in which case it is assumed that the application is using
		766	them. This means that AnyEvent will automatically pick the right backend
		767	when the main program loads an event module before anything starts to
		768	create watchers. Nothing special needs to be done by the main program.
		769
		770	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		771	AnyEvent::Impl::Tk based on Tk, very broken.
		772	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		773	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		774
		775	=item Backends with special needs.
		776
		777	Qt requires the Qt::Application to be instantiated first, but will
		778	otherwise be picked up automatically. As long as the main program
		779	instantiates the application before any AnyEvent watchers are created,
		780	everything should just work.
		781
		782	AnyEvent::Impl::Qt based on Qt.
		783
		784	Support for IO::Async can only be partial, as it is too broken and
		785	architecturally limited to even support the AnyEvent API. It also
		786	is the only event loop that needs the loop to be set explicitly, so
		787	it can only be used by a main program knowing about AnyEvent. See
		788	L<AnyEvent::Impl::Async> for the gory details.
		789
		790	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		791
		792	=item Event loops that are indirectly supported via other backends.
		793
		794	Some event loops can be supported via other modules:
		795
		796	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		797
		798	B<WxWidgets> has no support for watching file handles. However, you can
		799	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		800	polls 20 times per second, which was considered to be too horrible to even
		801	consider for AnyEvent.
		802
		803	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		804	backend, so it can be supported through POE.
		805
		806	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		807	load L<POE> when detecting them, in the hope that POE will pick them up,
		808	in which case everything will be automatic.
		809
		810	=back
		811
607	=head1 GLOBAL VARIABLES AND FUNCTIONS	812	=head1 GLOBAL VARIABLES AND FUNCTIONS
608		813
		814	These are not normally required to use AnyEvent, but can be useful to
		815	write AnyEvent extension modules.
		816
609	=over 4	817	=over 4
610		818
611	=item $AnyEvent::MODEL	819	=item $AnyEvent::MODEL
612		820
613	Contains C<undef> until the first watcher is being created. Then it	821	Contains C<undef> until the first watcher is being created, before the
		822	backend has been autodetected.
		823
614	contains the event model that is being used, which is the name of the	824	Afterwards it contains the event model that is being used, which is the
615	Perl class implementing the model. This class is usually one of the	825	name of the Perl class implementing the model. This class is usually one
616	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	826	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
617	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	827	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
618		828	will be C<urxvt::anyevent>).
619	The known classes so far are:
620
621	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
622	AnyEvent::Impl::Event based on Event, second best choice.
623	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
624	AnyEvent::Impl::Glib based on Glib, third-best choice.
625	AnyEvent::Impl::Tk based on Tk, very bad choice.
626	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
627	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
628	AnyEvent::Impl::POE based on POE, not generic enough for full support.
629
630	There is no support for WxWidgets, as WxWidgets has no support for
631	watching file handles. However, you can use WxWidgets through the
632	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
633	second, which was considered to be too horrible to even consider for
634	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
635	it's adaptor.
636
637	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
638	autodetecting them.
639		829
640	=item AnyEvent::detect	830	=item AnyEvent::detect
641		831
642	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	832	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
643	if necessary. You should only call this function right before you would	833	if necessary. You should only call this function right before you would
644	have created an AnyEvent watcher anyway, that is, as late as possible at	834	have created an AnyEvent watcher anyway, that is, as late as possible at
645	runtime.	835	runtime, and not e.g. while initialising of your module.
		836
		837	If you need to do some initialisation before AnyEvent watchers are
		838	created, use C<post_detect>.
646		839
647	=item $guard = AnyEvent::post_detect { BLOCK }	840	=item $guard = AnyEvent::post_detect { BLOCK }
648		841
649	Arranges for the code block to be executed as soon as the event model is	842	Arranges for the code block to be executed as soon as the event model is
650	autodetected (or immediately if this has already happened).	843	autodetected (or immediately if this has already happened).
		844
		845	The block will be executed I<after> the actual backend has been detected
		846	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		847	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		848	other initialisations - see the sources of L<AnyEvent::Strict> or
		849	L<AnyEvent::AIO> to see how this is used.
		850
		851	The most common usage is to create some global watchers, without forcing
		852	event module detection too early, for example, L<AnyEvent::AIO> creates
		853	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		854	avoid autodetecting the event module at load time.
651		855
652	If called in scalar or list context, then it creates and returns an object	856	If called in scalar or list context, then it creates and returns an object
653	that automatically removes the callback again when it is destroyed. See	857	that automatically removes the callback again when it is destroyed. See
654	L<Coro::BDB> for a case where this is useful.	858	L<Coro::BDB> for a case where this is useful.
655		859
…		…
658	If there are any code references in this array (you can C<push> to it	862	If there are any code references in this array (you can C<push> to it
659	before or after loading AnyEvent), then they will called directly after	863	before or after loading AnyEvent), then they will called directly after
660	the event loop has been chosen.	864	the event loop has been chosen.
661		865
662	You should check C<$AnyEvent::MODEL> before adding to this array, though:	866	You should check C<$AnyEvent::MODEL> before adding to this array, though:
663	if it contains a true value then the event loop has already been detected,	867	if it is defined then the event loop has already been detected, and the
664	and the array will be ignored.	868	array will be ignored.
665		869
666	Best use C<AnyEvent::post_detect { BLOCK }> instead.	870	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		871	it,as it takes care of these details.
		872
		873	This variable is mainly useful for modules that can do something useful
		874	when AnyEvent is used and thus want to know when it is initialised, but do
		875	not need to even load it by default. This array provides the means to hook
		876	into AnyEvent passively, without loading it.
667		877
668	=back	878	=back
669		879
670	=head1 WHAT TO DO IN A MODULE	880	=head1 WHAT TO DO IN A MODULE
671		881
…		…
726		936
727		937
728	=head1 OTHER MODULES	938	=head1 OTHER MODULES
729		939
730	The following is a non-exhaustive list of additional modules that use	940	The following is a non-exhaustive list of additional modules that use
731	AnyEvent and can therefore be mixed easily with other AnyEvent modules	941	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
732	in the same program. Some of the modules come with AnyEvent, some are	942	modules and other event loops in the same program. Some of the modules
733	available via CPAN.	943	come with AnyEvent, most are available via CPAN.
734		944
735	=over 4	945	=over 4
736		946
737	=item L<AnyEvent::Util>	947	=item L<AnyEvent::Util>
738		948
…		…
747		957
748	=item L<AnyEvent::Handle>	958	=item L<AnyEvent::Handle>
749		959
750	Provide read and write buffers, manages watchers for reads and writes,	960	Provide read and write buffers, manages watchers for reads and writes,
751	supports raw and formatted I/O, I/O queued and fully transparent and	961	supports raw and formatted I/O, I/O queued and fully transparent and
752	non-blocking SSL/TLS.	962	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
753		963
754	=item L<AnyEvent::DNS>	964	=item L<AnyEvent::DNS>
755		965
756	Provides rich asynchronous DNS resolver capabilities.	966	Provides rich asynchronous DNS resolver capabilities.
757		967
…		…
785		995
786	=item L<AnyEvent::GPSD>	996	=item L<AnyEvent::GPSD>
787		997
788	A non-blocking interface to gpsd, a daemon delivering GPS information.	998	A non-blocking interface to gpsd, a daemon delivering GPS information.
789		999
		1000	=item L<AnyEvent::IRC>
		1001
		1002	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1003
		1004	=item L<AnyEvent::XMPP>
		1005
		1006	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1007	Net::XMPP2>.
		1008
790	=item L<AnyEvent::IGS>	1009	=item L<AnyEvent::IGS>
791		1010
792	A non-blocking interface to the Internet Go Server protocol (used by	1011	A non-blocking interface to the Internet Go Server protocol (used by
793	L<App::IGS>).	1012	L<App::IGS>).
794		1013
795	=item L<Net::IRC3>
796
797	AnyEvent based IRC client module family.
798
799	=item L<Net::XMPP2>
800
801	AnyEvent based XMPP (Jabber protocol) module family.
802
803	=item L<Net::FCP>	1014	=item L<Net::FCP>
804		1015
805	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1016	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
806	of AnyEvent.	1017	of AnyEvent.
807		1018
…		…
811		1022
812	=item L<Coro>	1023	=item L<Coro>
813		1024
814	Has special support for AnyEvent via L<Coro::AnyEvent>.	1025	Has special support for AnyEvent via L<Coro::AnyEvent>.
815		1026
816	=item L<IO::Lambda>
817
818	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
819
820	=back	1027	=back
821		1028
822	=cut	1029	=cut
823		1030
824	package AnyEvent;	1031	package AnyEvent;
825		1032
826	no warnings;	1033	no warnings;
827	use strict;	1034	use strict qw(vars subs);
828		1035
829	use Carp;	1036	use Carp;
830		1037
831	our $VERSION = 4.2;	1038	our $VERSION = 4.801;
832	our $MODEL;	1039	our $MODEL;
833		1040
834	our $AUTOLOAD;	1041	our $AUTOLOAD;
835	our @ISA;	1042	our @ISA;
836		1043
837	our @REGISTRY;	1044	our @REGISTRY;
838		1045
839	our $WIN32;	1046	our $WIN32;
840		1047
841	BEGIN {	1048	BEGIN {
842	my $win32 = ! ! ($^O =~ /mswin32/i);	1049	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
843	eval "sub WIN32(){ $win32 }";	1050	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1051
		1052	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1053	if ${^TAINT};
844	}	1054	}
845		1055
846	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1056	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
847		1057
848	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred	1058	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
…		…
859	[Event:: => AnyEvent::Impl::Event::],	1069	[Event:: => AnyEvent::Impl::Event::],
860	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1070	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
861	# everything below here will not be autoprobed	1071	# everything below here will not be autoprobed
862	# as the pureperl backend should work everywhere	1072	# as the pureperl backend should work everywhere
863	# and is usually faster	1073	# and is usually faster
864	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
865	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1074	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
866	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1075	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1076	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1077	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
867	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1078	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
868	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
869	[Wx:: => AnyEvent::Impl::POE::],	1079	[Wx:: => AnyEvent::Impl::POE::],
870	[Prima:: => AnyEvent::Impl::POE::],	1080	[Prima:: => AnyEvent::Impl::POE::],
		1081	# IO::Async is just too broken - we would need workarounds for its
		1082	# byzantine signal and broken child handling, among others.
		1083	# IO::Async is rather hard to detect, as it doesn't have any
		1084	# obvious default class.
		1085	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1086	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1087	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
871	);	1088	);
872		1089
873	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1090	our %method = map +($_ => 1),
		1091	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
874		1092
875	our @post_detect;	1093	our @post_detect;
876		1094
877	sub post_detect(&) {	1095	sub post_detect(&) {
878	my ($cb) = @_;	1096	my ($cb) = @_;
…		…
883	1	1101	1
884	} else {	1102	} else {
885	push @post_detect, $cb;	1103	push @post_detect, $cb;
886		1104
887	defined wantarray	1105	defined wantarray
888	? bless \$cb, "AnyEvent::Util::PostDetect"	1106	? bless \$cb, "AnyEvent::Util::postdetect"
889	: ()	1107	: ()
890	}	1108	}
891	}	1109	}
892		1110
893	sub AnyEvent::Util::PostDetect::DESTROY {	1111	sub AnyEvent::Util::postdetect::DESTROY {
894	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1112	@post_detect = grep $_ != ${$_[0]}, @post_detect;
895	}	1113	}
896		1114
897	sub detect() {	1115	sub detect() {
898	unless ($MODEL) {	1116	unless ($MODEL) {
…		…
935	last;	1153	last;
936	}	1154	}
937	}	1155	}
938		1156
939	$MODEL	1157	$MODEL
940	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1158	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
941	}	1159	}
942	}	1160	}
943		1161
944	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1162	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
945		1163
…		…
966	}	1184	}
967		1185
968	# utility function to dup a filehandle. this is used by many backends	1186	# utility function to dup a filehandle. this is used by many backends
969	# to support binding more than one watcher per filehandle (they usually	1187	# to support binding more than one watcher per filehandle (they usually
970	# allow only one watcher per fd, so we dup it to get a different one).	1188	# allow only one watcher per fd, so we dup it to get a different one).
971	sub _dupfh($$$$) {	1189	sub _dupfh($$;$$) {
972	my ($poll, $fh, $r, $w) = @_;	1190	my ($poll, $fh, $r, $w) = @_;
973		1191
974	require Fcntl;
975
976	# cygwin requires the fh mode to be matching, unix doesn't	1192	# cygwin requires the fh mode to be matching, unix doesn't
977	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1193	my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">");
978	: $poll eq "w" ? ($w, ">")
979	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
980		1194
981	open my $fh2, "$mode&" . fileno $fh	1195	open my $fh2, "$mode&", $fh
982	or die "cannot dup() filehandle: $!";	1196	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
983		1197
984	# we assume CLOEXEC is already set by perl in all important cases	1198	# we assume CLOEXEC is already set by perl in all important cases
985		1199
986	($fh2, $rw)	1200	($fh2, $rw)
987	}	1201	}
988		1202
989	package AnyEvent::Base;	1203	package AnyEvent::Base;
990		1204
991	# default implementation for now and time	1205	# default implementations for many methods
992		1206
993	use Time::HiRes ();	1207	BEGIN {
		1208	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1209	*_time = \&Time::HiRes::time;
		1210	# if (eval "use POSIX (); (POSIX::times())...
		1211	} else {
		1212	*_time = sub { time }; # epic fail
		1213	}
		1214	}
994		1215
995	sub time { Time::HiRes::time }	1216	sub time { _time }
996	sub now { Time::HiRes::time }	1217	sub now { _time }
		1218	sub now_update { }
997		1219
998	# default implementation for ->condvar	1220	# default implementation for ->condvar
999		1221
1000	sub condvar {	1222	sub condvar {
1001	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1223	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1002	}	1224	}
1003		1225
1004	# default implementation for ->signal	1226	# default implementation for ->signal
1005		1227
1006	our %SIG_CB;	1228	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1229
		1230	sub _signal_exec {
		1231	sysread $SIGPIPE_R, my $dummy, 4;
		1232
		1233	while (%SIG_EV) {
		1234	for (keys %SIG_EV) {
		1235	delete $SIG_EV{$_};
		1236	$_->() for values %{ $SIG_CB{$_} \|\| {} };
		1237	}
		1238	}
		1239	}
1007		1240
1008	sub signal {	1241	sub signal {
1009	my (undef, %arg) = @_;	1242	my (undef, %arg) = @_;
1010		1243
		1244	unless ($SIGPIPE_R) {
		1245	require Fcntl;
		1246
		1247	if (AnyEvent::WIN32) {
		1248	require AnyEvent::Util;
		1249
		1250	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1251	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1252	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1253	} else {
		1254	pipe $SIGPIPE_R, $SIGPIPE_W;
		1255	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1256	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1257
		1258	# not strictly required, as $^F is normally 2, but let's make sure...
		1259	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1260	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1261	}
		1262
		1263	$SIGPIPE_R
		1264	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1265
		1266	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1267	}
		1268
1011	my $signal = uc $arg{signal}	1269	my $signal = uc $arg{signal}
1012	or Carp::croak "required option 'signal' is missing";	1270	or Carp::croak "required option 'signal' is missing";
1013		1271
1014	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1272	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1015	$SIG{$signal} \|\|= sub {	1273	$SIG{$signal} \|\|= sub {
1016	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1274	local $!;
		1275	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1276	undef $SIG_EV{$signal};
1017	};	1277	};
1018		1278
1019	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1279	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1020	}	1280	}
1021		1281
1022	sub AnyEvent::Base::Signal::DESTROY {	1282	sub AnyEvent::Base::signal::DESTROY {
1023	my ($signal, $cb) = @{$_[0]};	1283	my ($signal, $cb) = @{$_[0]};
1024		1284
1025	delete $SIG_CB{$signal}{$cb};	1285	delete $SIG_CB{$signal}{$cb};
1026		1286
		1287	# delete doesn't work with older perls - they then
		1288	# print weird messages, or just unconditionally exit
		1289	# instead of getting the default action.
1027	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1290	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1028	}	1291	}
1029		1292
1030	# default implementation for ->child	1293	# default implementation for ->child
1031		1294
1032	our %PID_CB;	1295	our %PID_CB;
1033	our $CHLD_W;	1296	our $CHLD_W;
1034	our $CHLD_DELAY_W;	1297	our $CHLD_DELAY_W;
1035	our $PID_IDLE;
1036	our $WNOHANG;	1298	our $WNOHANG;
1037		1299
1038	sub _child_wait {	1300	sub _sigchld {
1039	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1301	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
1040	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),	1302	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
1041	(values %{ $PID_CB{0} \|\| {} });	1303	(values %{ $PID_CB{0} \|\| {} });
1042	}	1304	}
1043
1044	undef $PID_IDLE;
1045	}
1046
1047	sub _sigchld {
1048	# make sure we deliver these changes "synchronous" with the event loop.
1049	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
1050	undef $CHLD_DELAY_W;
1051	&_child_wait;
1052	});
1053	}	1305	}
1054		1306
1055	sub child {	1307	sub child {
1056	my (undef, %arg) = @_;	1308	my (undef, %arg) = @_;
1057		1309
1058	defined (my $pid = $arg{pid} + 0)	1310	defined (my $pid = $arg{pid} + 0)
1059	or Carp::croak "required option 'pid' is missing";	1311	or Carp::croak "required option 'pid' is missing";
1060		1312
1061	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1313	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1062		1314
1063	unless ($WNOHANG) {
1064	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;	1315	$WNOHANG \|\|= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
1065	}
1066		1316
1067	unless ($CHLD_W) {	1317	unless ($CHLD_W) {
1068	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1318	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1069	# child could be a zombie already, so make at least one round	1319	# child could be a zombie already, so make at least one round
1070	&_sigchld;	1320	&_sigchld;
1071	}	1321	}
1072		1322
1073	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1323	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1074	}	1324	}
1075		1325
1076	sub AnyEvent::Base::Child::DESTROY {	1326	sub AnyEvent::Base::child::DESTROY {
1077	my ($pid, $cb) = @{$_[0]};	1327	my ($pid, $cb) = @{$_[0]};
1078		1328
1079	delete $PID_CB{$pid}{$cb};	1329	delete $PID_CB{$pid}{$cb};
1080	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1330	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1081		1331
1082	undef $CHLD_W unless keys %PID_CB;	1332	undef $CHLD_W unless keys %PID_CB;
		1333	}
		1334
		1335	# idle emulation is done by simply using a timer, regardless
		1336	# of whether the process is idle or not, and not letting
		1337	# the callback use more than 50% of the time.
		1338	sub idle {
		1339	my (undef, %arg) = @_;
		1340
		1341	my ($cb, $w, $rcb) = $arg{cb};
		1342
		1343	$rcb = sub {
		1344	if ($cb) {
		1345	$w = _time;
		1346	&$cb;
		1347	$w = _time - $w;
		1348
		1349	# never use more then 50% of the time for the idle watcher,
		1350	# within some limits
		1351	$w = 0.0001 if $w < 0.0001;
		1352	$w = 5 if $w > 5;
		1353
		1354	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1355	} else {
		1356	# clean up...
		1357	undef $w;
		1358	undef $rcb;
		1359	}
		1360	};
		1361
		1362	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1363
		1364	bless \\$cb, "AnyEvent::Base::idle"
		1365	}
		1366
		1367	sub AnyEvent::Base::idle::DESTROY {
		1368	undef $${$_[0]};
1083	}	1369	}
1084		1370
1085	package AnyEvent::CondVar;	1371	package AnyEvent::CondVar;
1086		1372
1087	our @ISA = AnyEvent::CondVar::Base::;	1373	our @ISA = AnyEvent::CondVar::Base::;
…		…
1139	}	1425	}
1140		1426
1141	# undocumented/compatibility with pre-3.4	1427	# undocumented/compatibility with pre-3.4
1142	*broadcast = \&send;	1428	*broadcast = \&send;
1143	*wait = \&_wait;	1429	*wait = \&_wait;
		1430
		1431	=head1 ERROR AND EXCEPTION HANDLING
		1432
		1433	In general, AnyEvent does not do any error handling - it relies on the
		1434	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1435	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1436	checking of all AnyEvent methods, however, which is highly useful during
		1437	development.
		1438
		1439	As for exception handling (i.e. runtime errors and exceptions thrown while
		1440	executing a callback), this is not only highly event-loop specific, but
		1441	also not in any way wrapped by this module, as this is the job of the main
		1442	program.
		1443
		1444	The pure perl event loop simply re-throws the exception (usually
		1445	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1446	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1447	so on.
		1448
		1449	=head1 ENVIRONMENT VARIABLES
		1450
		1451	The following environment variables are used by this module or its
		1452	submodules.
		1453
		1454	Note that AnyEvent will remove I<all> environment variables starting with
		1455	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1456	enabled.
		1457
		1458	=over 4
		1459
		1460	=item C<PERL_ANYEVENT_VERBOSE>
		1461
		1462	By default, AnyEvent will be completely silent except in fatal
		1463	conditions. You can set this environment variable to make AnyEvent more
		1464	talkative.
		1465
		1466	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1467	conditions, such as not being able to load the event model specified by
		1468	C<PERL_ANYEVENT_MODEL>.
		1469
		1470	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1471	model it chooses.
		1472
		1473	=item C<PERL_ANYEVENT_STRICT>
		1474
		1475	AnyEvent does not do much argument checking by default, as thorough
		1476	argument checking is very costly. Setting this variable to a true value
		1477	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1478	check the arguments passed to most method calls. If it finds any problems,
		1479	it will croak.
		1480
		1481	In other words, enables "strict" mode.
		1482
		1483	Unlike C<use strict>, it is definitely recommended to keep it off in
		1484	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1485	developing programs can be very useful, however.
		1486
		1487	=item C<PERL_ANYEVENT_MODEL>
		1488
		1489	This can be used to specify the event model to be used by AnyEvent, before
		1490	auto detection and -probing kicks in. It must be a string consisting
		1491	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1492	and the resulting module name is loaded and if the load was successful,
		1493	used as event model. If it fails to load AnyEvent will proceed with
		1494	auto detection and -probing.
		1495
		1496	This functionality might change in future versions.
		1497
		1498	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1499	could start your program like this:
		1500
		1501	PERL_ANYEVENT_MODEL=Perl perl ...
		1502
		1503	=item C<PERL_ANYEVENT_PROTOCOLS>
		1504
		1505	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1506	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1507	of auto probing).
		1508
		1509	Must be set to a comma-separated list of protocols or address families,
		1510	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1511	used, and preference will be given to protocols mentioned earlier in the
		1512	list.
		1513
		1514	This variable can effectively be used for denial-of-service attacks
		1515	against local programs (e.g. when setuid), although the impact is likely
		1516	small, as the program has to handle conenction and other failures anyways.
		1517
		1518	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1519	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1520	- only support IPv4, never try to resolve or contact IPv6
		1521	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1522	IPv6, but prefer IPv6 over IPv4.
		1523
		1524	=item C<PERL_ANYEVENT_EDNS0>
		1525
		1526	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1527	for DNS. This extension is generally useful to reduce DNS traffic, but
		1528	some (broken) firewalls drop such DNS packets, which is why it is off by
		1529	default.
		1530
		1531	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1532	EDNS0 in its DNS requests.
		1533
		1534	=item C<PERL_ANYEVENT_MAX_FORKS>
		1535
		1536	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1537	will create in parallel.
		1538
		1539	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1540
		1541	The default value for the C<max_outstanding> parameter for the default DNS
		1542	resolver - this is the maximum number of parallel DNS requests that are
		1543	sent to the DNS server.
		1544
		1545	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1546
		1547	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1548	configuration) in the default resolver. When set to the empty string, no
		1549	default config will be used.
		1550
		1551	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1552
		1553	When neither C<ca_file> nor C<ca_path> was specified during
		1554	L<AnyEvent::TLS> context creation, and either of these environment
		1555	variables exist, they will be used to specify CA certificate locations
		1556	instead of a system-dependent default.
		1557
		1558	=back
1144		1559
1145	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1560	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1146		1561
1147	This is an advanced topic that you do not normally need to use AnyEvent in	1562	This is an advanced topic that you do not normally need to use AnyEvent in
1148	a module. This section is only of use to event loop authors who want to	1563	a module. This section is only of use to event loop authors who want to
…		…
1182		1597
1183	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1598	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1184	condition variables: code blocking while waiting for a condition will	1599	condition variables: code blocking while waiting for a condition will
1185	C<die>. This still works with most modules/usages, and blocking calls must	1600	C<die>. This still works with most modules/usages, and blocking calls must
1186	not be done in an interactive application, so it makes sense.	1601	not be done in an interactive application, so it makes sense.
1187
1188	=head1 ENVIRONMENT VARIABLES
1189
1190	The following environment variables are used by this module:
1191
1192	=over 4
1193
1194	=item C<PERL_ANYEVENT_VERBOSE>
1195
1196	By default, AnyEvent will be completely silent except in fatal
1197	conditions. You can set this environment variable to make AnyEvent more
1198	talkative.
1199
1200	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1201	conditions, such as not being able to load the event model specified by
1202	C<PERL_ANYEVENT_MODEL>.
1203
1204	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1205	model it chooses.
1206
1207	=item C<PERL_ANYEVENT_STRICT>
1208
1209	AnyEvent does not do much argument checking by default, as thorough
1210	argument checking is very costly. Setting this variable to a true value
1211	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1212	check the arguments passed to most method calls. If it finds any problems
1213	it will croak.
1214
1215	In other words, enables "strict" mode.
1216
1217	Unlike C<use strict> it is definitely recommended ot keep it off in
1218	production.
1219
1220	=item C<PERL_ANYEVENT_MODEL>
1221
1222	This can be used to specify the event model to be used by AnyEvent, before
1223	auto detection and -probing kicks in. It must be a string consisting
1224	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1225	and the resulting module name is loaded and if the load was successful,
1226	used as event model. If it fails to load AnyEvent will proceed with
1227	auto detection and -probing.
1228
1229	This functionality might change in future versions.
1230
1231	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1232	could start your program like this:
1233
1234	PERL_ANYEVENT_MODEL=Perl perl ...
1235
1236	=item C<PERL_ANYEVENT_PROTOCOLS>
1237
1238	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1239	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1240	of auto probing).
1241
1242	Must be set to a comma-separated list of protocols or address families,
1243	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1244	used, and preference will be given to protocols mentioned earlier in the
1245	list.
1246
1247	This variable can effectively be used for denial-of-service attacks
1248	against local programs (e.g. when setuid), although the impact is likely
1249	small, as the program has to handle connection errors already-
1250
1251	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1252	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1253	- only support IPv4, never try to resolve or contact IPv6
1254	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1255	IPv6, but prefer IPv6 over IPv4.
1256
1257	=item C<PERL_ANYEVENT_EDNS0>
1258
1259	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1260	for DNS. This extension is generally useful to reduce DNS traffic, but
1261	some (broken) firewalls drop such DNS packets, which is why it is off by
1262	default.
1263
1264	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1265	EDNS0 in its DNS requests.
1266
1267	=item C<PERL_ANYEVENT_MAX_FORKS>
1268
1269	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1270	will create in parallel.
1271
1272	=back
1273		1602
1274	=head1 EXAMPLE PROGRAM	1603	=head1 EXAMPLE PROGRAM
1275		1604
1276	The following program uses an I/O watcher to read data from STDIN, a timer	1605	The following program uses an I/O watcher to read data from STDIN, a timer
1277	to display a message once per second, and a condition variable to quit the	1606	to display a message once per second, and a condition variable to quit the
…		…
1471	watcher.	1800	watcher.
1472		1801
1473	=head3 Results	1802	=head3 Results
1474		1803
1475	name watchers bytes create invoke destroy comment	1804	name watchers bytes create invoke destroy comment
1476	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1805	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1477	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1806	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1478	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1807	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1479	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1808	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1480	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1809	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1481	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1810	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1811	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1812	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1482	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1813	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1483	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1814	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1484	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1815	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1485	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1816	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1486		1817
1487	=head3 Discussion	1818	=head3 Discussion
1488		1819
1489	The benchmark does I<not> measure scalability of the event loop very	1820	The benchmark does I<not> measure scalability of the event loop very
1490	well. For example, a select-based event loop (such as the pure perl one)	1821	well. For example, a select-based event loop (such as the pure perl one)
…		…
1515	performance becomes really bad with lots of file descriptors (and few of	1846	performance becomes really bad with lots of file descriptors (and few of
1516	them active), of course, but this was not subject of this benchmark.	1847	them active), of course, but this was not subject of this benchmark.
1517		1848
1518	The C<Event> module has a relatively high setup and callback invocation	1849	The C<Event> module has a relatively high setup and callback invocation
1519	cost, but overall scores in on the third place.	1850	cost, but overall scores in on the third place.
		1851
		1852	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1853	when using its pure perl backend.
1520		1854
1521	C<Glib>'s memory usage is quite a bit higher, but it features a	1855	C<Glib>'s memory usage is quite a bit higher, but it features a
1522	faster callback invocation and overall ends up in the same class as	1856	faster callback invocation and overall ends up in the same class as
1523	C<Event>. However, Glib scales extremely badly, doubling the number of	1857	C<Event>. However, Glib scales extremely badly, doubling the number of
1524	watchers increases the processing time by more than a factor of four,	1858	watchers increases the processing time by more than a factor of four,
…		…
1602	it to another server. This includes deleting the old timeout and creating	1936	it to another server. This includes deleting the old timeout and creating
1603	a new one that moves the timeout into the future.	1937	a new one that moves the timeout into the future.
1604		1938
1605	=head3 Results	1939	=head3 Results
1606		1940
1607	name sockets create request	1941	name sockets create request
1608	EV 20000 69.01 11.16	1942	EV 20000 69.01 11.16
1609	Perl 20000 73.32 35.87	1943	Perl 20000 73.32 35.87
		1944	IOAsync 20000 157.00 98.14 epoll
		1945	IOAsync 20000 159.31 616.06 poll
1610	Event 20000 212.62 257.32	1946	Event 20000 212.62 257.32
1611	Glib 20000 651.16 1896.30	1947	Glib 20000 651.16 1896.30
1612	POE 20000 349.67 12317.24 uses POE::Loop::Event	1948	POE 20000 349.67 12317.24 uses POE::Loop::Event
1613		1949
1614	=head3 Discussion	1950	=head3 Discussion
1615		1951
1616	This benchmark I<does> measure scalability and overall performance of the	1952	This benchmark I<does> measure scalability and overall performance of the
1617	particular event loop.	1953	particular event loop.
…		…
1619	EV is again fastest. Since it is using epoll on my system, the setup time	1955	EV is again fastest. Since it is using epoll on my system, the setup time
1620	is relatively high, though.	1956	is relatively high, though.
1621		1957
1622	Perl surprisingly comes second. It is much faster than the C-based event	1958	Perl surprisingly comes second. It is much faster than the C-based event
1623	loops Event and Glib.	1959	loops Event and Glib.
		1960
		1961	IO::Async performs very well when using its epoll backend, and still quite
		1962	good compared to Glib when using its pure perl backend.
1624		1963
1625	Event suffers from high setup time as well (look at its code and you will	1964	Event suffers from high setup time as well (look at its code and you will
1626	understand why). Callback invocation also has a high overhead compared to	1965	understand why). Callback invocation also has a high overhead compared to
1627	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1966	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1628	uses select or poll in basically all documented configurations.	1967	uses select or poll in basically all documented configurations.
…		…
1691	=item * C-based event loops perform very well with small number of	2030	=item * C-based event loops perform very well with small number of
1692	watchers, as the management overhead dominates.	2031	watchers, as the management overhead dominates.
1693		2032
1694	=back	2033	=back
1695		2034
		2035	=head2 THE IO::Lambda BENCHMARK
		2036
		2037	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2038	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2039	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2040	shouldn't come as a surprise to anybody). As such, the benchmark is
		2041	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2042	very optimal. But how would AnyEvent compare when used without the extra
		2043	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2044
		2045	The benchmark itself creates an echo-server, and then, for 500 times,
		2046	connects to the echo server, sends a line, waits for the reply, and then
		2047	creates the next connection. This is a rather bad benchmark, as it doesn't
		2048	test the efficiency of the framework or much non-blocking I/O, but it is a
		2049	benchmark nevertheless.
		2050
		2051	name runtime
		2052	Lambda/select 0.330 sec
		2053	+ optimized 0.122 sec
		2054	Lambda/AnyEvent 0.327 sec
		2055	+ optimized 0.138 sec
		2056	Raw sockets/select 0.077 sec
		2057	POE/select, components 0.662 sec
		2058	POE/select, raw sockets 0.226 sec
		2059	POE/select, optimized 0.404 sec
		2060
		2061	AnyEvent/select/nb 0.085 sec
		2062	AnyEvent/EV/nb 0.068 sec
		2063	+state machine 0.134 sec
		2064
		2065	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2066	benchmarks actually make blocking connects and use 100% blocking I/O,
		2067	defeating the purpose of an event-based solution. All of the newly
		2068	written AnyEvent benchmarks use 100% non-blocking connects (using
		2069	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2070	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2071	generally require a lot more bookkeeping and event handling than blocking
		2072	connects (which involve a single syscall only).
		2073
		2074	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2075	offers similar expressive power as POE and IO::Lambda, using conventional
		2076	Perl syntax. This means that both the echo server and the client are 100%
		2077	non-blocking, further placing it at a disadvantage.
		2078
		2079	As you can see, the AnyEvent + EV combination even beats the
		2080	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2081	backend easily beats IO::Lambda and POE.
		2082
		2083	And even the 100% non-blocking version written using the high-level (and
		2084	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2085	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2086	in a non-blocking way.
		2087
		2088	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2089	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2090	part of the IO::lambda distribution and were used without any changes.
		2091
		2092
		2093	=head1 SIGNALS
		2094
		2095	AnyEvent currently installs handlers for these signals:
		2096
		2097	=over 4
		2098
		2099	=item SIGCHLD
		2100
		2101	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2102	emulation for event loops that do not support them natively. Also, some
		2103	event loops install a similar handler.
		2104
		2105	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		2106	reset it to default, to avoid losing child exit statuses.
		2107
		2108	=item SIGPIPE
		2109
		2110	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2111	when AnyEvent gets loaded.
		2112
		2113	The rationale for this is that AnyEvent users usually do not really depend
		2114	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2115	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2116	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2117	some random socket.
		2118
		2119	The rationale for installing a no-op handler as opposed to ignoring it is
		2120	that this way, the handler will be restored to defaults on exec.
		2121
		2122	Feel free to install your own handler, or reset it to defaults.
		2123
		2124	=back
		2125
		2126	=cut
		2127
		2128	undef $SIG{CHLD}
		2129	if $SIG{CHLD} eq 'IGNORE';
		2130
		2131	$SIG{PIPE} = sub { }
		2132	unless defined $SIG{PIPE};
1696		2133
1697	=head1 FORK	2134	=head1 FORK
1698		2135
1699	Most event libraries are not fork-safe. The ones who are usually are	2136	Most event libraries are not fork-safe. The ones who are usually are
1700	because they rely on inefficient but fork-safe C<select> or C<poll>	2137	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1721	use AnyEvent;	2158	use AnyEvent;
1722		2159
1723	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2160	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1724	be used to probe what backend is used and gain other information (which is	2161	be used to probe what backend is used and gain other information (which is
1725	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2162	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1726	$ENV{PERL_ANYEGENT_STRICT}.	2163	$ENV{PERL_ANYEVENT_STRICT}.
		2164
		2165	Note that AnyEvent will remove I<all> environment variables starting with
		2166	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2167	enabled.
1727		2168
1728		2169
1729	=head1 BUGS	2170	=head1 BUGS
1730		2171
1731	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2172	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1732	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2173	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1733	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2174	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1734	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2175	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1735	pronounced).	2176	pronounced).
1736		2177
1737		2178
1738	=head1 SEE ALSO	2179	=head1 SEE ALSO
1739		2180
…		…
1743	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2184	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1744		2185
1745	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2186	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1746	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2187	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1747	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2188	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1748	L<AnyEvent::Impl::POE>.	2189	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1749		2190
1750	Non-blocking file handles, sockets, TCP clients and	2191	Non-blocking file handles, sockets, TCP clients and
1751	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2192	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1752		2193
1753	Asynchronous DNS: L<AnyEvent::DNS>.	2194	Asynchronous DNS: L<AnyEvent::DNS>.
1754		2195
1755	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2196	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2197	L<Coro::Event>,
1756		2198
1757	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2199	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2200	L<AnyEvent::HTTP>.
1758		2201
1759		2202
1760	=head1 AUTHOR	2203	=head1 AUTHOR
1761		2204
1762	Marc Lehmann <schmorp@schmorp.de>	2205	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.170 by root, Wed Jul 9 11:53:40 2008 UTC vs. Revision 1.233 by root, Thu Jul 9 01:22:50 2009 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.170 by root, Wed Jul 9 11:53:40 2008 UTC vs.
Revision 1.233 by root, Thu Jul 9 01:22:50 2009 UTC