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Revision 1.169 by root, Wed Jul 9 10:36:22 2008 UTC vs.
Revision 1.263 by root, Wed Jul 29 12:39:21 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
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 { $_[0]->recv });
22		39
23	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
24		41
25	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
27	L<AnyEvent::Intro> manpage.	44	L<AnyEvent::Intro> manpage.
		45
		46	=head1 SUPPORT
		47
		48	There is a mailinglist for discussing all things AnyEvent, and an IRC
		49	channel, too.
		50
		51	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		52	Repository>, at L<http://anyevent.schmorp.de>, for more info.
28		53
29	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
30		55
31	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
32	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
…		…
128	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
129	creating a watcher it will immediately "watch" for events and invoke the	154	creating a watcher it will immediately "watch" for events and invoke the
130	callback when the event occurs (of course, only when the event model	155	callback when the event occurs (of course, only when the event model
131	is in control).	156	is in control).
132		157
		158	Note that B<callbacks must not permanently change global variables>
		159	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		160	callbacks must not C<die> >>. The former is good programming practise in
		161	Perl and the latter stems from the fact that exception handling differs
		162	widely between event loops.
		163
133	To disable the watcher you have to destroy it (e.g. by setting the	164	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	165	variable you store it in to C<undef> or otherwise deleting all references
135	to it).	166	to it).
136		167
137	All watchers are created by calling a method on the C<AnyEvent> class.	168	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
153	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
154		185
155	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	186	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
156	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
157		188
158	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	189	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>	190	for events (AnyEvent might or might not keep a reference to this file
		191	handle). Note that only file handles pointing to things for which
		192	non-blocking operation makes sense are allowed. This includes sockets,
		193	most character devices, pipes, fifos and so on, but not for example files
		194	or block devices.
		195
160	must be a string that is either C<r> or C<w>, which creates a watcher	196	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	197	watcher waiting for "r"eadable or "w"ritable events, respectively.
		198
162	callback to invoke each time the file handle becomes ready.	199	C<cb> is the callback to invoke each time the file handle becomes ready.
163		200
164	Although the callback might get passed parameters, their value and	201	Although the callback might get passed parameters, their value and
165	presence is undefined and you cannot rely on them. Portable AnyEvent	202	presence is undefined and you cannot rely on them. Portable AnyEvent
166	callbacks cannot use arguments passed to I/O watcher callbacks.	203	callbacks cannot use arguments passed to I/O watcher callbacks.
167		204
…		…
299	In either case, if you care (and in most cases, you don't), then you	336	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	337	can get whatever behaviour you want with any event loop, by taking the
301	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	338	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
302	account.	339	account.
303		340
		341	=item AnyEvent->now_update
		342
		343	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		344	the current time for each loop iteration (see the discussion of L<<
		345	AnyEvent->now >>, above).
		346
		347	When a callback runs for a long time (or when the process sleeps), then
		348	this "current" time will differ substantially from the real time, which
		349	might affect timers and time-outs.
		350
		351	When this is the case, you can call this method, which will update the
		352	event loop's idea of "current time".
		353
		354	Note that updating the time I<might> cause some events to be handled.
		355
304	=back	356	=back
305		357
306	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
307		359
308	You can watch for signals using a signal watcher, C<signal> is the signal	360	You can watch for signals using a signal watcher, C<signal> is the signal
…		…
317	invocation, and callback invocation will be synchronous. Synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
318	that it might take a while until the signal gets handled by the process,	370	that it might take a while until the signal gets handled by the process,
319	but it is guaranteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
320		372
321	The main advantage of using these watchers is that you can share a signal	373	The main advantage of using these watchers is that you can share a signal
322	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
323		376
324	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
325	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
326		380
327	Example: exit on SIGINT	381	Example: exit on SIGINT
328		382
329	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
330		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		392	seconds). This variable can be changed only before the first signal
		393	watcher is created, and should be left alone otherwise. Higher values
		394	will cause fewer spurious wake-ups, which is better for power and CPU
		395	saving. All these problems can be avoided by installing the optional
		396	L<Async::Interrupt> module. This will not work with inherently broken
		397	event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
		398	currently, as POE does it's own workaround with one-second latency). With
		399	those, you just have to suffer the delays.
		400
331	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
332		402
333	You can also watch on a child process exit and catch its exit status.	403	You can also watch on a child process exit and catch its exit status.
334		404
335	The child process is specified by the C<pid> argument (if set to C<0>, it	405	The child process is specified by the C<pid> argument (one some backends,
336	watches for any child process exit). The watcher will trigger as often	406	using C<0> watches for any child process exit, on others this will
337	as status change for the child are received. This works by installing a	407	croak). The watcher will be triggered only when the child process has
338	signal handler for C<SIGCHLD>. The callback will be called with the pid	408	finished and an exit status is available, not on any trace events
339	and exit status (as returned by waitpid), so unlike other watcher types,	409	(stopped/continued).
340	you I<can> rely on child watcher callback arguments.	410
		411	The callback will be called with the pid and exit status (as returned by
		412	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		413	callback arguments.
		414
		415	This watcher type works by installing a signal handler for C<SIGCHLD>,
		416	and since it cannot be shared, nothing else should use SIGCHLD or reap
		417	random child processes (waiting for specific child processes, e.g. inside
		418	C<system>, is just fine).
341		419
342	There is a slight catch to child watchers, however: you usually start them	420	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	421	I<after> the child process was created, and this means the process could
344	have exited already (and no SIGCHLD will be sent anymore).	422	have exited already (and no SIGCHLD will be sent anymore).
345		423
346	Not all event models handle this correctly (POE doesn't), but even for	424	Not all event models handle this correctly (neither POE nor IO::Async do,
		425	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	426	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).	427	the process exits (i.e. before you fork in the first place). AnyEvent's
		428	pure perl event loop handles all cases correctly regardless of when you
		429	start the watcher.
349		430
350	This means you cannot create a child watcher as the very first thing in an	431	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	432	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>).	433	watcher before you C<fork> the child (alternatively, you can call
		434	C<AnyEvent::detect>).
		435
		436	As most event loops do not support waiting for child events, they will be
		437	emulated by AnyEvent in most cases, in which the latency and race problems
		438	mentioned in the description of signal watchers apply.
353		439
354	Example: fork a process and wait for it	440	Example: fork a process and wait for it
355		441
356	my $done = AnyEvent->condvar;	442	my $done = AnyEvent->condvar;
357		443
…		…
367	);	453	);
368		454
369	# do something else, then wait for process exit	455	# do something else, then wait for process exit
370	$done->recv;	456	$done->recv;
371		457
		458	=head2 IDLE WATCHERS
		459
		460	Sometimes there is a need to do something, but it is not so important
		461	to do it instantly, but only when there is nothing better to do. This
		462	"nothing better to do" is usually defined to be "no other events need
		463	attention by the event loop".
		464
		465	Idle watchers ideally get invoked when the event loop has nothing
		466	better to do, just before it would block the process to wait for new
		467	events. Instead of blocking, the idle watcher is invoked.
		468
		469	Most event loops unfortunately do not really support idle watchers (only
		470	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		471	will simply call the callback "from time to time".
		472
		473	Example: read lines from STDIN, but only process them when the
		474	program is otherwise idle:
		475
		476	my @lines; # read data
		477	my $idle_w;
		478	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		479	push @lines, scalar <STDIN>;
		480
		481	# start an idle watcher, if not already done
		482	$idle_w ||= AnyEvent->idle (cb => sub {
		483	# handle only one line, when there are lines left
		484	if (my $line = shift @lines) {
		485	print "handled when idle: $line";
		486	} else {
		487	# otherwise disable the idle watcher again
		488	undef $idle_w;
		489	}
		490	});
		491	});
		492
372	=head2 CONDITION VARIABLES	493	=head2 CONDITION VARIABLES
373		494
374	If you are familiar with some event loops you will know that all of them	495	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	496	require you to run some blocking "loop", "run" or similar function that
376	will actively watch for new events and call your callbacks.	497	will actively watch for new events and call your callbacks.
377		498
378	AnyEvent is different, it expects somebody else to run the event loop and	499	AnyEvent is slightly different: it expects somebody else to run the event
379	will only block when necessary (usually when told by the user).	500	loop and will only block when necessary (usually when told by the user).
380		501
381	The instrument to do that is called a "condition variable", so called	502	The instrument to do that is called a "condition variable", so called
382	because they represent a condition that must become true.	503	because they represent a condition that must become true.
		504
		505	Now is probably a good time to look at the examples further below.
383		506
384	Condition variables can be created by calling the C<< AnyEvent->condvar	507	Condition variables can be created by calling the C<< AnyEvent->condvar
385	>> method, usually without arguments. The only argument pair allowed is	508	>> method, usually without arguments. The only argument pair allowed is
386	C<cb>, which specifies a callback to be called when the condition variable	509	C<cb>, which specifies a callback to be called when the condition variable
387	becomes true.	510	becomes true, with the condition variable as the first argument (but not
		511	the results).
388		512
389	After creation, the condition variable is "false" until it becomes "true"	513	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	514	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<<	515	were a callback, read about the caveats in the description for the C<<
392	->send >> method).	516	->send >> method).
…		…
394	Condition variables are similar to callbacks, except that you can	518	Condition variables are similar to callbacks, except that you can
395	optionally wait for them. They can also be called merge points - points	519	optionally wait for them. They can also be called merge points - points
396	in time where multiple outstanding events have been processed. And yet	520	in time where multiple outstanding events have been processed. And yet
397	another way to call them is transactions - each condition variable can be	521	another way to call them is transactions - each condition variable can be
398	used to represent a transaction, which finishes at some point and delivers	522	used to represent a transaction, which finishes at some point and delivers
399	a result.	523	a result. And yet some people know them as "futures" - a promise to
		524	compute/deliver something that you can wait for.
400		525
401	Condition variables are very useful to signal that something has finished,	526	Condition variables are very useful to signal that something has finished,
402	for example, if you write a module that does asynchronous http requests,	527	for example, if you write a module that does asynchronous http requests,
403	then a condition variable would be the ideal candidate to signal the	528	then a condition variable would be the ideal candidate to signal the
404	availability of results. The user can either act when the callback is	529	availability of results. The user can either act when the callback is
…		…
438	after => 1,	563	after => 1,
439	cb => sub { $result_ready->send },	564	cb => sub { $result_ready->send },
440	);	565	);
441		566
442	# this "blocks" (while handling events) till the callback	567	# this "blocks" (while handling events) till the callback
443	# calls send	568	# calls -<send
444	$result_ready->recv;	569	$result_ready->recv;
445		570
446	Example: wait for a timer, but take advantage of the fact that	571	Example: wait for a timer, but take advantage of the fact that condition
447	condition variables are also code references.	572	variables are also callable directly.
448		573
449	my $done = AnyEvent->condvar;	574	my $done = AnyEvent->condvar;
450	my $delay = AnyEvent->timer (after => 5, cb => $done);	575	my $delay = AnyEvent->timer (after => 5, cb => $done);
451	$done->recv;	576	$done->recv;
		577
		578	Example: Imagine an API that returns a condvar and doesn't support
		579	callbacks. This is how you make a synchronous call, for example from
		580	the main program:
		581
		582	use AnyEvent::CouchDB;
		583
		584	...
		585
		586	my @info = $couchdb->info->recv;
		587
		588	And this is how you would just set a callback to be called whenever the
		589	results are available:
		590
		591	$couchdb->info->cb (sub {
		592	my @info = $_[0]->recv;
		593	});
452		594
453	=head3 METHODS FOR PRODUCERS	595	=head3 METHODS FOR PRODUCERS
454		596
455	These methods should only be used by the producing side, i.e. the	597	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	598	code/module that eventually sends the signal. Note that it is also
…		…
469	immediately from within send.	611	immediately from within send.
470		612
471	Any arguments passed to the C<send> call will be returned by all	613	Any arguments passed to the C<send> call will be returned by all
472	future C<< ->recv >> calls.	614	future C<< ->recv >> calls.
473		615
474	Condition variables are overloaded so one can call them directly	616	Condition variables are overloaded so one can call them directly (as if
475	(as a code reference). Calling them directly is the same as calling	617	they were a code reference). Calling them directly is the same as calling
476	C<send>. Note, however, that many C-based event loops do not handle	618	C<send>.
477	overloading, so as tempting as it may be, passing a condition variable
478	instead of a callback does not work. Both the pure perl and EV loops
479	support overloading, however, as well as all functions that use perl to
480	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
481	example).
482		619
483	=item $cv->croak ($error)	620	=item $cv->croak ($error)
484		621
485	Similar to send, but causes all call's to C<< ->recv >> to invoke	622	Similar to send, but causes all call's to C<< ->recv >> to invoke
486	C<Carp::croak> with the given error message/object/scalar.	623	C<Carp::croak> with the given error message/object/scalar.
487		624
488	This can be used to signal any errors to the condition variable	625	This can be used to signal any errors to the condition variable
489	user/consumer.	626	user/consumer. Doing it this way instead of calling C<croak> directly
		627	delays the error detetcion, but has the overwhelmign advantage that it
		628	diagnoses the error at the place where the result is expected, and not
		629	deep in some event clalback without connection to the actual code causing
		630	the problem.
490		631
491	=item $cv->begin ([group callback])	632	=item $cv->begin ([group callback])
492		633
493	=item $cv->end	634	=item $cv->end
494
495	These two methods are EXPERIMENTAL and MIGHT CHANGE.
496		635
497	These two methods can be used to combine many transactions/events into	636	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	637	one. For example, a function that pings many hosts in parallel might want
499	to use a condition variable for the whole process.	638	to use a condition variable for the whole process.
500		639
…		…
502	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	641	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	642	>>, 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	643	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.	644	callback was set, C<send> will be called without any arguments.
506		645
507	Let's clarify this with the ping example:	646	You can think of C<< $cv->send >> giving you an OR condition (one call
		647	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		648	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		649
		650	Let's start with a simple example: you have two I/O watchers (for example,
		651	STDOUT and STDERR for a program), and you want to wait for both streams to
		652	close before activating a condvar:
		653
		654	my $cv = AnyEvent->condvar;
		655
		656	$cv->begin; # first watcher
		657	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		658	defined sysread $fh1, my $buf, 4096
		659	or $cv->end;
		660	});
		661
		662	$cv->begin; # second watcher
		663	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		664	defined sysread $fh2, my $buf, 4096
		665	or $cv->end;
		666	});
		667
		668	$cv->recv;
		669
		670	This works because for every event source (EOF on file handle), there is
		671	one call to C<begin>, so the condvar waits for all calls to C<end> before
		672	sending.
		673
		674	The ping example mentioned above is slightly more complicated, as the
		675	there are results to be passwd back, and the number of tasks that are
		676	begung can potentially be zero:
508		677
509	my $cv = AnyEvent->condvar;	678	my $cv = AnyEvent->condvar;
510		679
511	my %result;	680	my %result;
512	$cv->begin (sub { $cv->send (\%result) });	681	$cv->begin (sub { $cv->send (\%result) });
…		…
532	loop, which serves two important purposes: first, it sets the callback	701	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	702	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	703	C<send> is called even when C<no> hosts are being pinged (the loop
535	doesn't execute once).	704	doesn't execute once).
536		705
537	This is the general pattern when you "fan out" into multiple subrequests:	706	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>	707	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	708	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>.	709	subrequest you start, call C<begin> and for each subrequest you finish,
		710	call C<end>.
541		711
542	=back	712	=back
543		713
544	=head3 METHODS FOR CONSUMERS	714	=head3 METHODS FOR CONSUMERS
545		715
…		…
561	function will call C<croak>.	731	function will call C<croak>.
562		732
563	In list context, all parameters passed to C<send> will be returned,	733	In list context, all parameters passed to C<send> will be returned,
564	in scalar context only the first one will be returned.	734	in scalar context only the first one will be returned.
565		735
		736	Note that doing a blocking wait in a callback is not supported by any
		737	event loop, that is, recursive invocation of a blocking C<< ->recv
		738	>> is not allowed, and the C<recv> call will C<croak> if such a
		739	condition is detected. This condition can be slightly loosened by using
		740	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		741	any thread that doesn't run the event loop itself.
		742
566	Not all event models support a blocking wait - some die in that case	743	Not all event models support a blocking wait - some die in that case
567	(programs might want to do that to stay interactive), so I<if you are	744	(programs might want to do that to stay interactive), so I<if you are
568	using this from a module, never require a blocking wait>, but let the	745	using this from a module, never require a blocking wait>. Instead, let the
569	caller decide whether the call will block or not (for example, by coupling	746	caller decide whether the call will block or not (for example, by coupling
570	condition variables with some kind of request results and supporting	747	condition variables with some kind of request results and supporting
571	callbacks so the caller knows that getting the result will not block,	748	callbacks so the caller knows that getting the result will not block,
572	while still supporting blocking waits if the caller so desires).	749	while still supporting blocking waits if the caller so desires).
573		750
574	Another reason I<never> to C<< ->recv >> in a module is that you cannot
575	sensibly have two C<< ->recv >>'s in parallel, as that would require
576	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
577	can supply.
578
579	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
580	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
581	versions and also integrates coroutines into AnyEvent, making blocking
582	C<< ->recv >> calls perfectly safe as long as they are done from another
583	coroutine (one that doesn't run the event loop).
584
585	You can ensure that C<< -recv >> never blocks by setting a callback and	751	You can ensure that C<< -recv >> never blocks by setting a callback and
586	only calling C<< ->recv >> from within that callback (or at a later	752	only calling C<< ->recv >> from within that callback (or at a later
587	time). This will work even when the event loop does not support blocking	753	time). This will work even when the event loop does not support blocking
588	waits otherwise.	754	waits otherwise.
589		755
590	=item $bool = $cv->ready	756	=item $bool = $cv->ready
591		757
592	Returns true when the condition is "true", i.e. whether C<send> or	758	Returns true when the condition is "true", i.e. whether C<send> or
593	C<croak> have been called.	759	C<croak> have been called.
594		760
595	=item $cb = $cv->cb ([new callback])	761	=item $cb = $cv->cb ($cb->($cv))
596		762
597	This is a mutator function that returns the callback set and optionally	763	This is a mutator function that returns the callback set and optionally
598	replaces it before doing so.	764	replaces it before doing so.
599		765
600	The callback will be called when the condition becomes "true", i.e. when	766	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	768	variable itself. Calling C<recv> inside the callback or at any later time
603	is guaranteed not to block.	769	is guaranteed not to block.
604		770
605	=back	771	=back
606		772
		773	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		774
		775	The available backend classes are (every class has its own manpage):
		776
		777	=over 4
		778
		779	=item Backends that are autoprobed when no other event loop can be found.
		780
		781	EV is the preferred backend when no other event loop seems to be in
		782	use. If EV is not installed, then AnyEvent will try Event, and, failing
		783	that, will fall back to its own pure-perl implementation, which is
		784	available everywhere as it comes with AnyEvent itself.
		785
		786	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		787	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		788	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		789
		790	=item Backends that are transparently being picked up when they are used.
		791
		792	These will be used when they are currently loaded when the first watcher
		793	is created, in which case it is assumed that the application is using
		794	them. This means that AnyEvent will automatically pick the right backend
		795	when the main program loads an event module before anything starts to
		796	create watchers. Nothing special needs to be done by the main program.
		797
		798	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		799	AnyEvent::Impl::Tk based on Tk, very broken.
		800	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		801	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		802	AnyEvent::Impl::Irssi used when running within irssi.
		803
		804	=item Backends with special needs.
		805
		806	Qt requires the Qt::Application to be instantiated first, but will
		807	otherwise be picked up automatically. As long as the main program
		808	instantiates the application before any AnyEvent watchers are created,
		809	everything should just work.
		810
		811	AnyEvent::Impl::Qt based on Qt.
		812
		813	Support for IO::Async can only be partial, as it is too broken and
		814	architecturally limited to even support the AnyEvent API. It also
		815	is the only event loop that needs the loop to be set explicitly, so
		816	it can only be used by a main program knowing about AnyEvent. See
		817	L<AnyEvent::Impl::Async> for the gory details.
		818
		819	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		820
		821	=item Event loops that are indirectly supported via other backends.
		822
		823	Some event loops can be supported via other modules:
		824
		825	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		826
		827	B<WxWidgets> has no support for watching file handles. However, you can
		828	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		829	polls 20 times per second, which was considered to be too horrible to even
		830	consider for AnyEvent.
		831
		832	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		833	backend, so it can be supported through POE.
		834
		835	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		836	load L<POE> when detecting them, in the hope that POE will pick them up,
		837	in which case everything will be automatic.
		838
		839	=back
		840
607	=head1 GLOBAL VARIABLES AND FUNCTIONS	841	=head1 GLOBAL VARIABLES AND FUNCTIONS
608		842
		843	These are not normally required to use AnyEvent, but can be useful to
		844	write AnyEvent extension modules.
		845
609	=over 4	846	=over 4
610		847
611	=item $AnyEvent::MODEL	848	=item $AnyEvent::MODEL
612		849
613	Contains C<undef> until the first watcher is being created. Then it	850	Contains C<undef> until the first watcher is being created, before the
		851	backend has been autodetected.
		852
614	contains the event model that is being used, which is the name of the	853	Afterwards it contains the event model that is being used, which is the
615	Perl class implementing the model. This class is usually one of the	854	name of the Perl class implementing the model. This class is usually one
616	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	855	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
617	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	856	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
618		857	will be C<urxvt::anyevent>).
619	The known classes so far are:
620
621	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
622	AnyEvent::Impl::Event based on Event, second best choice.
623	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
624	AnyEvent::Impl::Glib based on Glib, third-best choice.
625	AnyEvent::Impl::Tk based on Tk, very bad choice.
626	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
627	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
628	AnyEvent::Impl::POE based on POE, not generic enough for full support.
629
630	There is no support for WxWidgets, as WxWidgets has no support for
631	watching file handles. However, you can use WxWidgets through the
632	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
633	second, which was considered to be too horrible to even consider for
634	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
635	it's adaptor.
636
637	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
638	autodetecting them.
639		858
640	=item AnyEvent::detect	859	=item AnyEvent::detect
641		860
642	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	861	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
643	if necessary. You should only call this function right before you would	862	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	863	have created an AnyEvent watcher anyway, that is, as late as possible at
645	runtime.	864	runtime, and not e.g. while initialising of your module.
		865
		866	If you need to do some initialisation before AnyEvent watchers are
		867	created, use C<post_detect>.
646		868
647	=item $guard = AnyEvent::post_detect { BLOCK }	869	=item $guard = AnyEvent::post_detect { BLOCK }
648		870
649	Arranges for the code block to be executed as soon as the event model is	871	Arranges for the code block to be executed as soon as the event model is
650	autodetected (or immediately if this has already happened).	872	autodetected (or immediately if this has already happened).
651		873
		874	The block will be executed I<after> the actual backend has been detected
		875	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		876	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		877	other initialisations - see the sources of L<AnyEvent::Strict> or
		878	L<AnyEvent::AIO> to see how this is used.
		879
		880	The most common usage is to create some global watchers, without forcing
		881	event module detection too early, for example, L<AnyEvent::AIO> creates
		882	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		883	avoid autodetecting the event module at load time.
		884
652	If called in scalar or list context, then it creates and returns an object	885	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	886	that automatically removes the callback again when it is destroyed (or
		887	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
654	L<Coro::BDB> for a case where this is useful.	888	a case where this is useful.
		889
		890	Example: Create a watcher for the IO::AIO module and store it in
		891	C<$WATCHER>. Only do so after the event loop is initialised, though.
		892
		893	our WATCHER;
		894
		895	my $guard = AnyEvent::post_detect {
		896	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		897	};
		898
		899	# the ||= is important in case post_detect immediately runs the block,
		900	# as to not clobber the newly-created watcher. assigning both watcher and
		901	# post_detect guard to the same variable has the advantage of users being
		902	# able to just C<undef $WATCHER> if the watcher causes them grief.
		903
		904	$WATCHER ||= $guard;
655		905
656	=item @AnyEvent::post_detect	906	=item @AnyEvent::post_detect
657		907
658	If there are any code references in this array (you can C<push> to it	908	If there are any code references in this array (you can C<push> to it
659	before or after loading AnyEvent), then they will called directly after	909	before or after loading AnyEvent), then they will called directly after
660	the event loop has been chosen.	910	the event loop has been chosen.
661		911
662	You should check C<$AnyEvent::MODEL> before adding to this array, though:	912	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,	913	if it is defined then the event loop has already been detected, and the
664	and the array will be ignored.	914	array will be ignored.
665		915
666	Best use C<AnyEvent::post_detect { BLOCK }> instead.	916	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		917	it,as it takes care of these details.
		918
		919	This variable is mainly useful for modules that can do something useful
		920	when AnyEvent is used and thus want to know when it is initialised, but do
		921	not need to even load it by default. This array provides the means to hook
		922	into AnyEvent passively, without loading it.
667		923
668	=back	924	=back
669		925
670	=head1 WHAT TO DO IN A MODULE	926	=head1 WHAT TO DO IN A MODULE
671		927
…		…
726		982
727		983
728	=head1 OTHER MODULES	984	=head1 OTHER MODULES
729		985
730	The following is a non-exhaustive list of additional modules that use	986	The following is a non-exhaustive list of additional modules that use
731	AnyEvent and can therefore be mixed easily with other AnyEvent modules	987	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	988	modules and other event loops in the same program. Some of the modules
733	available via CPAN.	989	come with AnyEvent, most are available via CPAN.
734		990
735	=over 4	991	=over 4
736		992
737	=item L<AnyEvent::Util>	993	=item L<AnyEvent::Util>
738		994
…		…
747		1003
748	=item L<AnyEvent::Handle>	1004	=item L<AnyEvent::Handle>
749		1005
750	Provide read and write buffers, manages watchers for reads and writes,	1006	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	1007	supports raw and formatted I/O, I/O queued and fully transparent and
752	non-blocking SSL/TLS.	1008	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
753		1009
754	=item L<AnyEvent::DNS>	1010	=item L<AnyEvent::DNS>
755		1011
756	Provides rich asynchronous DNS resolver capabilities.	1012	Provides rich asynchronous DNS resolver capabilities.
757		1013
…		…
785		1041
786	=item L<AnyEvent::GPSD>	1042	=item L<AnyEvent::GPSD>
787		1043
788	A non-blocking interface to gpsd, a daemon delivering GPS information.	1044	A non-blocking interface to gpsd, a daemon delivering GPS information.
789		1045
		1046	=item L<AnyEvent::IRC>
		1047
		1048	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1049
		1050	=item L<AnyEvent::XMPP>
		1051
		1052	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1053	Net::XMPP2>.
		1054
790	=item L<AnyEvent::IGS>	1055	=item L<AnyEvent::IGS>
791		1056
792	A non-blocking interface to the Internet Go Server protocol (used by	1057	A non-blocking interface to the Internet Go Server protocol (used by
793	L<App::IGS>).	1058	L<App::IGS>).
794		1059
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>	1060	=item L<Net::FCP>
804		1061
805	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1062	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
806	of AnyEvent.	1063	of AnyEvent.
807		1064
…		…
811		1068
812	=item L<Coro>	1069	=item L<Coro>
813		1070
814	Has special support for AnyEvent via L<Coro::AnyEvent>.	1071	Has special support for AnyEvent via L<Coro::AnyEvent>.
815		1072
816	=item L<IO::Lambda>
817
818	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
819
820	=back	1073	=back
821		1074
822	=cut	1075	=cut
823		1076
824	package AnyEvent;	1077	package AnyEvent;
825		1078
		1079	# basically a tuned-down version of common::sense
		1080	sub common_sense {
826	no warnings;	1081	# no warnings
827	use strict;	1082	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1083	# use strict vars subs
		1084	$^H |= 0x00000600;
		1085	}
828		1086
		1087	BEGIN { AnyEvent::common_sense }
		1088
829	use Carp;	1089	use Carp ();
830		1090
831	our $VERSION = 4.2;	1091	our $VERSION = 4.881;
832	our $MODEL;	1092	our $MODEL;
833		1093
834	our $AUTOLOAD;	1094	our $AUTOLOAD;
835	our @ISA;	1095	our @ISA;
836		1096
837	our @REGISTRY;	1097	our @REGISTRY;
838		1098
839	our $WIN32;	1099	our $WIN32;
840		1100
		1101	our $VERBOSE;
		1102
841	BEGIN {	1103	BEGIN {
842	my $win32 = ! ! ($^O =~ /mswin32/i);	1104	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
843	eval "sub WIN32(){ $win32 }";	1105	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
844	}
845		1106
		1107	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1108	if ${^TAINT};
		1109
846	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1110	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1111
		1112	}
		1113
		1114	our $MAX_SIGNAL_LATENCY = 10;
847		1115
848	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1116	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
849		1117
850	{	1118	{
851	my $idx;	1119	my $idx;
…		…
853	for reverse split /\s*,\s*/,	1121	for reverse split /\s*,\s*/,
854	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1122	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
855	}	1123	}
856		1124
857	my @models = (	1125	my @models = (
858	[EV:: => AnyEvent::Impl::EV::],	1126	[EV:: => AnyEvent::Impl::EV:: , 1],
859	[Event:: => AnyEvent::Impl::Event::],	1127	[Event:: => AnyEvent::Impl::Event::, 1],
860	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1128	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
861	# everything below here will not be autoprobed	1129	# everything below here will not (normally) be autoprobed
862	# as the pureperl backend should work everywhere	1130	# as the pureperl backend should work everywhere
863	# and is usually faster	1131	# and is usually faster
		1132	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1133	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1134	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
864	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1135	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
865	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
866	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
867	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1136	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
868	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1137	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
869	[Wx:: => AnyEvent::Impl::POE::],	1138	[Wx:: => AnyEvent::Impl::POE::],
870	[Prima:: => AnyEvent::Impl::POE::],	1139	[Prima:: => AnyEvent::Impl::POE::],
		1140	# IO::Async is just too broken - we would need workarounds for its
		1141	# byzantine signal and broken child handling, among others.
		1142	# IO::Async is rather hard to detect, as it doesn't have any
		1143	# obvious default class.
		1144	# [0, IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1145	# [0, IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1146	# [0, IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
871	);	1147	);
872		1148
873	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1149	our %method = map +($_ => 1),
		1150	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
874		1151
875	our @post_detect;	1152	our @post_detect;
876		1153
877	sub post_detect(&) {	1154	sub post_detect(&) {
878	my ($cb) = @_;	1155	my ($cb) = @_;
879		1156
880	if ($MODEL) {	1157	if ($MODEL) {
881	$cb->();	1158	$cb->();
882		1159
883	1	1160	undef
884	} else {	1161	} else {
885	push @post_detect, $cb;	1162	push @post_detect, $cb;
886		1163
887	defined wantarray	1164	defined wantarray
888	? bless \$cb, "AnyEvent::Util::PostDetect"	1165	? bless \$cb, "AnyEvent::Util::postdetect"
889	: ()	1166	: ()
890	}	1167	}
891	}	1168	}
892		1169
893	sub AnyEvent::Util::PostDetect::DESTROY {	1170	sub AnyEvent::Util::postdetect::DESTROY {
894	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1171	@post_detect = grep $_ != ${$_[0]}, @post_detect;
895	}	1172	}
896		1173
897	sub detect() {	1174	sub detect() {
898	unless ($MODEL) {	1175	unless ($MODEL) {
899	no strict 'refs';
900	local $SIG{__DIE__};	1176	local $SIG{__DIE__};
901		1177
902	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1178	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
903	my $model = "AnyEvent::Impl::$1";	1179	my $model = "AnyEvent::Impl::$1";
904	if (eval "require $model") {	1180	if (eval "require $model") {
905	$MODEL = $model;	1181	$MODEL = $model;
906	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1182	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
907	} else {	1183	} else {
908	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1184	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
909	}	1185	}
910	}	1186	}
911		1187
912	# check for already loaded models	1188	# check for already loaded models
913	unless ($MODEL) {	1189	unless ($MODEL) {
914	for (@REGISTRY, @models) {	1190	for (@REGISTRY, @models) {
915	my ($package, $model) = @$_;	1191	my ($package, $model) = @$_;
916	if (${"$package\::VERSION"} > 0) {	1192	if (${"$package\::VERSION"} > 0) {
917	if (eval "require $model") {	1193	if (eval "require $model") {
918	$MODEL = $model;	1194	$MODEL = $model;
919	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1195	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
920	last;	1196	last;
921	}	1197	}
922	}	1198	}
923	}	1199	}
924		1200
925	unless ($MODEL) {	1201	unless ($MODEL) {
926	# try to load a model	1202	# try to autoload a model
927
928	for (@REGISTRY, @models) {	1203	for (@REGISTRY, @models) {
929	my ($package, $model) = @$_;	1204	my ($package, $model, $autoload) = @$_;
		1205	if (
		1206	$autoload
930	if (eval "require $package"	1207	and eval "require $package"
931	and ${"$package\::VERSION"} > 0	1208	and ${"$package\::VERSION"} > 0
932	and eval "require $model") {	1209	and eval "require $model"
		1210	) {
933	$MODEL = $model;	1211	$MODEL = $model;
934	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1212	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
935	last;	1213	last;
936	}	1214	}
937	}	1215	}
938		1216
939	$MODEL	1217	$MODEL
940	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1218	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
941	}	1219	}
942	}	1220	}
943		1221
944	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1222	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
945		1223
…		…
955		1233
956	sub AUTOLOAD {	1234	sub AUTOLOAD {
957	(my $func = $AUTOLOAD) =~ s/.*://;	1235	(my $func = $AUTOLOAD) =~ s/.*://;
958		1236
959	$method{$func}	1237	$method{$func}
960	or croak "$func: not a valid method for AnyEvent objects";	1238	or Carp::croak "$func: not a valid method for AnyEvent objects";
961		1239
962	detect unless $MODEL;	1240	detect unless $MODEL;
963		1241
964	my $class = shift;	1242	my $class = shift;
965	$class->$func (@_);	1243	$class->$func (@_);
966	}	1244	}
967		1245
968	# utility function to dup a filehandle. this is used by many backends	1246	# utility function to dup a filehandle. this is used by many backends
969	# to support binding more than one watcher per filehandle (they usually	1247	# 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).	1248	# allow only one watcher per fd, so we dup it to get a different one).
971	sub _dupfh($$$$) {	1249	sub _dupfh($$;$$) {
972	my ($poll, $fh, $r, $w) = @_;	1250	my ($poll, $fh, $r, $w) = @_;
973		1251
974	require Fcntl;
975
976	# cygwin requires the fh mode to be matching, unix doesn't	1252	# cygwin requires the fh mode to be matching, unix doesn't
977	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1253	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		1254
981	open my $fh2, "$mode&" . fileno $fh	1255	open my $fh2, $mode, $fh
982	or die "cannot dup() filehandle: $!";	1256	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
983		1257
984	# we assume CLOEXEC is already set by perl in all important cases	1258	# we assume CLOEXEC is already set by perl in all important cases
985		1259
986	($fh2, $rw)	1260	($fh2, $rw)
987	}	1261	}
988		1262
989	package AnyEvent::Base;	1263	package AnyEvent::Base;
990		1264
991	# default implementation for now and time	1265	# default implementations for many methods
992		1266
993	use Time::HiRes ();	1267	sub _time {
		1268	# probe for availability of Time::HiRes
		1269	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1270	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1271	*_time = \&Time::HiRes::time;
		1272	# if (eval "use POSIX (); (POSIX::times())...
		1273	} else {
		1274	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1275	*_time = sub { time }; # epic fail
		1276	}
994		1277
995	sub time { Time::HiRes::time }	1278	&_time
996	sub now { Time::HiRes::time }	1279	}
		1280
		1281	sub time { _time }
		1282	sub now { _time }
		1283	sub now_update { }
997		1284
998	# default implementation for ->condvar	1285	# default implementation for ->condvar
999		1286
1000	sub condvar {	1287	sub condvar {
1001	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1288	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1002	}	1289	}
1003		1290
1004	# default implementation for ->signal	1291	# default implementation for ->signal
1005		1292
1006	our %SIG_CB;	1293	our $HAVE_ASYNC_INTERRUPT;
1007		1294
		1295	sub _have_async_interrupt() {
		1296	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1297	&& eval "use Async::Interrupt 1.0 (); 1")
		1298	unless defined $HAVE_ASYNC_INTERRUPT;
		1299
		1300	$HAVE_ASYNC_INTERRUPT
		1301	}
		1302
		1303	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1304	our (%SIG_ASY, %SIG_ASY_W);
		1305	our ($SIG_COUNT, $SIG_TW);
		1306
		1307	sub _signal_exec {
		1308	$HAVE_ASYNC_INTERRUPT
		1309	? $SIGPIPE_R->drain
		1310	: sysread $SIGPIPE_R, my $dummy, 9;
		1311
		1312	while (%SIG_EV) {
		1313	for (keys %SIG_EV) {
		1314	delete $SIG_EV{$_};
		1315	$_->() for values %{ $SIG_CB{$_} || {} };
		1316	}
		1317	}
		1318	}
		1319
		1320	# install a dummy wakeup watcher to reduce signal catching latency
		1321	sub _sig_add() {
		1322	unless ($SIG_COUNT++) {
		1323	# try to align timer on a full-second boundary, if possible
		1324	my $NOW = AnyEvent->now;
		1325
		1326	$SIG_TW = AnyEvent->timer (
		1327	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1328	interval => $MAX_SIGNAL_LATENCY,
		1329	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1330	);
		1331	}
		1332	}
		1333
		1334	sub _sig_del {
		1335	undef $SIG_TW
		1336	unless --$SIG_COUNT;
		1337	}
		1338
		1339	our %SIGNAME2NUM;
		1340	our @SIGNUM2NAME;
		1341	our $_sig_name_init; $_sig_name_init = sub {
		1342	undef $_sig_name_init;
		1343
		1344	if (_have_async_interrupt) {
		1345	*sig2num = \&Async::Interrupt::sig2num;
		1346	*sig2name = \&Async::Interrupt::sig2name;
		1347	} else {
		1348	require Config;
		1349
		1350	@SIGNAME2NUM{ split ' ', $Config::Config{sig_name} }
		1351	= split ' ', $Config::Config{sig_num};
		1352	@SIGNUM2NAME[values %SIGNAME2NUM] = keys %SIGNAME2NUM;
		1353
		1354	*sig2num = sub($) {
		1355	$_[0] > 0 ? shift : $SIGNAME2NUM{+shift}
		1356	};
		1357	*sig2name = sub ($) {
		1358	$_[0] > 0 ? $SIGNUM2NAME[+shift] : shift
		1359	};
		1360	}
		1361	};
		1362
		1363	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1364	sub sig2name($) { &$_sig_name_init; &sig2name }
		1365
1008	sub signal {	1366	sub _signal {
1009	my (undef, %arg) = @_;	1367	my (undef, %arg) = @_;
1010		1368
1011	my $signal = uc $arg{signal}	1369	my $signal = uc $arg{signal}
1012	or Carp::croak "required option 'signal' is missing";	1370	or Carp::croak "required option 'signal' is missing";
1013		1371
		1372	if ($HAVE_ASYNC_INTERRUPT) {
		1373	# async::interrupt
		1374
		1375	$signal = sig2num $signal;
1014	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1376	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1377
		1378	$SIG_ASY{$signal} ||= new Async::Interrupt
		1379	cb => sub { undef $SIG_EV{$signal} },
		1380	signal => $signal,
		1381	pipe => [$SIGPIPE_R->filenos],
		1382	pipe_autodrain => 0,
		1383	;
		1384
		1385	} else {
		1386	# pure perl
		1387
		1388	# AE::Util has been loaded in signal
		1389	$signal = sig2name $signal;
		1390	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1391
1015	$SIG{$signal} ||= sub {	1392	$SIG{$signal} ||= sub {
1016	$_->() for values %{ $SIG_CB{$signal} || {} };	1393	local $!;
		1394	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1395	undef $SIG_EV{$signal};
		1396	};
		1397
		1398	# can't do signal processing without introducing races in pure perl,
		1399	# so limit the signal latency.
		1400	_sig_add;
1017	};	1401	}
1018		1402
1019	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1403	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1020	}	1404	}
1021		1405
		1406	sub signal {
		1407	# probe for availability of Async::Interrupt
		1408	if (_have_async_interrupt) {
		1409	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1410
		1411	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1412	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1413
		1414	} else {
		1415	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1416
		1417	require Fcntl;
		1418
		1419	if (AnyEvent::WIN32) {
		1420	require AnyEvent::Util;
		1421
		1422	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1423	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1424	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1425	} else {
		1426	pipe $SIGPIPE_R, $SIGPIPE_W;
		1427	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1428	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1429
		1430	# not strictly required, as $^F is normally 2, but let's make sure...
		1431	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1432	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1433	}
		1434
		1435	$SIGPIPE_R
		1436	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1437
		1438	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1439	}
		1440
		1441	*signal = \&_signal;
		1442	&signal
		1443	}
		1444
1022	sub AnyEvent::Base::Signal::DESTROY {	1445	sub AnyEvent::Base::signal::DESTROY {
1023	my ($signal, $cb) = @{$_[0]};	1446	my ($signal, $cb) = @{$_[0]};
1024		1447
		1448	_sig_del;
		1449
1025	delete $SIG_CB{$signal}{$cb};	1450	delete $SIG_CB{$signal}{$cb};
1026		1451
		1452	$HAVE_ASYNC_INTERRUPT
		1453	? delete $SIG_ASY{$signal}
		1454	: # delete doesn't work with older perls - they then
		1455	# print weird messages, or just unconditionally exit
		1456	# instead of getting the default action.
		1457	undef $SIG{$signal}
1027	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1458	unless keys %{ $SIG_CB{$signal} };
1028	}	1459	}
1029		1460
1030	# default implementation for ->child	1461	# default implementation for ->child
1031		1462
1032	our %PID_CB;	1463	our %PID_CB;
1033	our $CHLD_W;	1464	our $CHLD_W;
1034	our $CHLD_DELAY_W;	1465	our $CHLD_DELAY_W;
1035	our $PID_IDLE;
1036	our $WNOHANG;	1466	our $WNOHANG;
1037		1467
1038	sub _child_wait {	1468	sub _emit_childstatus($$) {
1039	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1469	my (undef, $rpid, $rstatus) = @_;
		1470
		1471	$_->($rpid, $rstatus)
1040	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1472	for values %{ $PID_CB{$rpid} || {} },
1041	(values %{ $PID_CB{0} || {} });	1473	values %{ $PID_CB{0} || {} };
1042	}
1043
1044	undef $PID_IDLE;
1045	}	1474	}
1046		1475
1047	sub _sigchld {	1476	sub _sigchld {
1048	# make sure we deliver these changes "synchronous" with the event loop.	1477	my $pid;
1049	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1478
1050	undef $CHLD_DELAY_W;	1479	AnyEvent->_emit_childstatus ($pid, $?)
1051	&_child_wait;	1480	while ($pid = waitpid -1, $WNOHANG) > 0;
1052	});
1053	}	1481	}
1054		1482
1055	sub child {	1483	sub child {
1056	my (undef, %arg) = @_;	1484	my (undef, %arg) = @_;
1057		1485
1058	defined (my $pid = $arg{pid} + 0)	1486	defined (my $pid = $arg{pid} + 0)
1059	or Carp::croak "required option 'pid' is missing";	1487	or Carp::croak "required option 'pid' is missing";
1060		1488
1061	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1489	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1062		1490
1063	unless ($WNOHANG) {	1491	# WNOHANG is almost cetrainly 1 everywhere
		1492	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1493	? 1
1064	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1494	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1065	}
1066		1495
1067	unless ($CHLD_W) {	1496	unless ($CHLD_W) {
1068	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1497	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1069	# child could be a zombie already, so make at least one round	1498	# child could be a zombie already, so make at least one round
1070	&_sigchld;	1499	&_sigchld;
1071	}	1500	}
1072		1501
1073	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1502	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1074	}	1503	}
1075		1504
1076	sub AnyEvent::Base::Child::DESTROY {	1505	sub AnyEvent::Base::child::DESTROY {
1077	my ($pid, $cb) = @{$_[0]};	1506	my ($pid, $cb) = @{$_[0]};
1078		1507
1079	delete $PID_CB{$pid}{$cb};	1508	delete $PID_CB{$pid}{$cb};
1080	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1509	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1081		1510
1082	undef $CHLD_W unless keys %PID_CB;	1511	undef $CHLD_W unless keys %PID_CB;
1083	}	1512	}
1084		1513
		1514	# idle emulation is done by simply using a timer, regardless
		1515	# of whether the process is idle or not, and not letting
		1516	# the callback use more than 50% of the time.
		1517	sub idle {
		1518	my (undef, %arg) = @_;
		1519
		1520	my ($cb, $w, $rcb) = $arg{cb};
		1521
		1522	$rcb = sub {
		1523	if ($cb) {
		1524	$w = _time;
		1525	&$cb;
		1526	$w = _time - $w;
		1527
		1528	# never use more then 50% of the time for the idle watcher,
		1529	# within some limits
		1530	$w = 0.0001 if $w < 0.0001;
		1531	$w = 5 if $w > 5;
		1532
		1533	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1534	} else {
		1535	# clean up...
		1536	undef $w;
		1537	undef $rcb;
		1538	}
		1539	};
		1540
		1541	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1542
		1543	bless \\$cb, "AnyEvent::Base::idle"
		1544	}
		1545
		1546	sub AnyEvent::Base::idle::DESTROY {
		1547	undef $${$_[0]};
		1548	}
		1549
1085	package AnyEvent::CondVar;	1550	package AnyEvent::CondVar;
1086		1551
1087	our @ISA = AnyEvent::CondVar::Base::;	1552	our @ISA = AnyEvent::CondVar::Base::;
1088		1553
1089	package AnyEvent::CondVar::Base;	1554	package AnyEvent::CondVar::Base;
1090		1555
1091	use overload	1556	#use overload
1092	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1557	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1093	fallback => 1;	1558	# fallback => 1;
		1559
		1560	# save 300+ kilobytes by dirtily hardcoding overloading
		1561	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1562	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1563	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1564	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1565
		1566	our $WAITING;
1094		1567
1095	sub _send {	1568	sub _send {
1096	# nop	1569	# nop
1097	}	1570	}
1098		1571
…		…
1111	sub ready {	1584	sub ready {
1112	$_[0]{_ae_sent}	1585	$_[0]{_ae_sent}
1113	}	1586	}
1114		1587
1115	sub _wait {	1588	sub _wait {
		1589	$WAITING
		1590	and !$_[0]{_ae_sent}
		1591	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1592
		1593	local $WAITING = 1;
1116	AnyEvent->one_event while !$_[0]{_ae_sent};	1594	AnyEvent->one_event while !$_[0]{_ae_sent};
1117	}	1595	}
1118		1596
1119	sub recv {	1597	sub recv {
1120	$_[0]->_wait;	1598	$_[0]->_wait;
…		…
1139	}	1617	}
1140		1618
1141	# undocumented/compatibility with pre-3.4	1619	# undocumented/compatibility with pre-3.4
1142	*broadcast = \&send;	1620	*broadcast = \&send;
1143	*wait = \&_wait;	1621	*wait = \&_wait;
		1622
		1623	=head1 ERROR AND EXCEPTION HANDLING
		1624
		1625	In general, AnyEvent does not do any error handling - it relies on the
		1626	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1627	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1628	checking of all AnyEvent methods, however, which is highly useful during
		1629	development.
		1630
		1631	As for exception handling (i.e. runtime errors and exceptions thrown while
		1632	executing a callback), this is not only highly event-loop specific, but
		1633	also not in any way wrapped by this module, as this is the job of the main
		1634	program.
		1635
		1636	The pure perl event loop simply re-throws the exception (usually
		1637	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1638	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1639	so on.
		1640
		1641	=head1 ENVIRONMENT VARIABLES
		1642
		1643	The following environment variables are used by this module or its
		1644	submodules.
		1645
		1646	Note that AnyEvent will remove I<all> environment variables starting with
		1647	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1648	enabled.
		1649
		1650	=over 4
		1651
		1652	=item C<PERL_ANYEVENT_VERBOSE>
		1653
		1654	By default, AnyEvent will be completely silent except in fatal
		1655	conditions. You can set this environment variable to make AnyEvent more
		1656	talkative.
		1657
		1658	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1659	conditions, such as not being able to load the event model specified by
		1660	C<PERL_ANYEVENT_MODEL>.
		1661
		1662	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1663	model it chooses.
		1664
		1665	When set to C<8> or higher, then AnyEvent will report extra information on
		1666	which optional modules it loads and how it implements certain features.
		1667
		1668	=item C<PERL_ANYEVENT_STRICT>
		1669
		1670	AnyEvent does not do much argument checking by default, as thorough
		1671	argument checking is very costly. Setting this variable to a true value
		1672	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1673	check the arguments passed to most method calls. If it finds any problems,
		1674	it will croak.
		1675
		1676	In other words, enables "strict" mode.
		1677
		1678	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1679	>>, it is definitely recommended to keep it off in production. Keeping
		1680	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1681	can be very useful, however.
		1682
		1683	=item C<PERL_ANYEVENT_MODEL>
		1684
		1685	This can be used to specify the event model to be used by AnyEvent, before
		1686	auto detection and -probing kicks in. It must be a string consisting
		1687	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1688	and the resulting module name is loaded and if the load was successful,
		1689	used as event model. If it fails to load AnyEvent will proceed with
		1690	auto detection and -probing.
		1691
		1692	This functionality might change in future versions.
		1693
		1694	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1695	could start your program like this:
		1696
		1697	PERL_ANYEVENT_MODEL=Perl perl ...
		1698
		1699	=item C<PERL_ANYEVENT_PROTOCOLS>
		1700
		1701	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1702	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1703	of auto probing).
		1704
		1705	Must be set to a comma-separated list of protocols or address families,
		1706	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1707	used, and preference will be given to protocols mentioned earlier in the
		1708	list.
		1709
		1710	This variable can effectively be used for denial-of-service attacks
		1711	against local programs (e.g. when setuid), although the impact is likely
		1712	small, as the program has to handle conenction and other failures anyways.
		1713
		1714	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1715	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1716	- only support IPv4, never try to resolve or contact IPv6
		1717	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1718	IPv6, but prefer IPv6 over IPv4.
		1719
		1720	=item C<PERL_ANYEVENT_EDNS0>
		1721
		1722	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1723	for DNS. This extension is generally useful to reduce DNS traffic, but
		1724	some (broken) firewalls drop such DNS packets, which is why it is off by
		1725	default.
		1726
		1727	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1728	EDNS0 in its DNS requests.
		1729
		1730	=item C<PERL_ANYEVENT_MAX_FORKS>
		1731
		1732	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1733	will create in parallel.
		1734
		1735	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1736
		1737	The default value for the C<max_outstanding> parameter for the default DNS
		1738	resolver - this is the maximum number of parallel DNS requests that are
		1739	sent to the DNS server.
		1740
		1741	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1742
		1743	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1744	configuration) in the default resolver. When set to the empty string, no
		1745	default config will be used.
		1746
		1747	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1748
		1749	When neither C<ca_file> nor C<ca_path> was specified during
		1750	L<AnyEvent::TLS> context creation, and either of these environment
		1751	variables exist, they will be used to specify CA certificate locations
		1752	instead of a system-dependent default.
		1753
		1754	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1755
		1756	When these are set to C<1>, then the respective modules are not
		1757	loaded. Mostly good for testing AnyEvent itself.
		1758
		1759	=back
1144		1760
1145	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1761	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1146		1762
1147	This is an advanced topic that you do not normally need to use AnyEvent in	1763	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	1764	a module. This section is only of use to event loop authors who want to
…		…
1182		1798
1183	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1799	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1184	condition variables: code blocking while waiting for a condition will	1800	condition variables: code blocking while waiting for a condition will
1185	C<die>. This still works with most modules/usages, and blocking calls must	1801	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.	1802	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 thoroughly check the arguments passed to most
1212	method calls and croaks if it finds any problems. In other words, enables
1213	"strict" mode. Unlike C<use strict> it is definitely recommended ot keep
1214	it off in production.
1215
1216	=item C<PERL_ANYEVENT_MODEL>
1217
1218	This can be used to specify the event model to be used by AnyEvent, before
1219	auto detection and -probing kicks in. It must be a string consisting
1220	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1221	and the resulting module name is loaded and if the load was successful,
1222	used as event model. If it fails to load AnyEvent will proceed with
1223	auto detection and -probing.
1224
1225	This functionality might change in future versions.
1226
1227	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1228	could start your program like this:
1229
1230	PERL_ANYEVENT_MODEL=Perl perl ...
1231
1232	=item C<PERL_ANYEVENT_PROTOCOLS>
1233
1234	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1235	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1236	of auto probing).
1237
1238	Must be set to a comma-separated list of protocols or address families,
1239	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1240	used, and preference will be given to protocols mentioned earlier in the
1241	list.
1242
1243	This variable can effectively be used for denial-of-service attacks
1244	against local programs (e.g. when setuid), although the impact is likely
1245	small, as the program has to handle connection errors already-
1246
1247	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1248	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1249	- only support IPv4, never try to resolve or contact IPv6
1250	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1251	IPv6, but prefer IPv6 over IPv4.
1252
1253	=item C<PERL_ANYEVENT_EDNS0>
1254
1255	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1256	for DNS. This extension is generally useful to reduce DNS traffic, but
1257	some (broken) firewalls drop such DNS packets, which is why it is off by
1258	default.
1259
1260	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1261	EDNS0 in its DNS requests.
1262
1263	=item C<PERL_ANYEVENT_MAX_FORKS>
1264
1265	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1266	will create in parallel.
1267
1268	=back
1269		1803
1270	=head1 EXAMPLE PROGRAM	1804	=head1 EXAMPLE PROGRAM
1271		1805
1272	The following program uses an I/O watcher to read data from STDIN, a timer	1806	The following program uses an I/O watcher to read data from STDIN, a timer
1273	to display a message once per second, and a condition variable to quit the	1807	to display a message once per second, and a condition variable to quit the
…		…
1467	watcher.	2001	watcher.
1468		2002
1469	=head3 Results	2003	=head3 Results
1470		2004
1471	name watchers bytes create invoke destroy comment	2005	name watchers bytes create invoke destroy comment
1472	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2006	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1473	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2007	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1474	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2008	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1475	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2009	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1476	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2010	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1477	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2011	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		2012	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		2013	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1478	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2014	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1479	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2015	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1480	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2016	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1481	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2017	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1482		2018
1483	=head3 Discussion	2019	=head3 Discussion
1484		2020
1485	The benchmark does I<not> measure scalability of the event loop very	2021	The benchmark does I<not> measure scalability of the event loop very
1486	well. For example, a select-based event loop (such as the pure perl one)	2022	well. For example, a select-based event loop (such as the pure perl one)
…		…
1511	performance becomes really bad with lots of file descriptors (and few of	2047	performance becomes really bad with lots of file descriptors (and few of
1512	them active), of course, but this was not subject of this benchmark.	2048	them active), of course, but this was not subject of this benchmark.
1513		2049
1514	The C<Event> module has a relatively high setup and callback invocation	2050	The C<Event> module has a relatively high setup and callback invocation
1515	cost, but overall scores in on the third place.	2051	cost, but overall scores in on the third place.
		2052
		2053	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2054	when using its pure perl backend.
1516		2055
1517	C<Glib>'s memory usage is quite a bit higher, but it features a	2056	C<Glib>'s memory usage is quite a bit higher, but it features a
1518	faster callback invocation and overall ends up in the same class as	2057	faster callback invocation and overall ends up in the same class as
1519	C<Event>. However, Glib scales extremely badly, doubling the number of	2058	C<Event>. However, Glib scales extremely badly, doubling the number of
1520	watchers increases the processing time by more than a factor of four,	2059	watchers increases the processing time by more than a factor of four,
…		…
1598	it to another server. This includes deleting the old timeout and creating	2137	it to another server. This includes deleting the old timeout and creating
1599	a new one that moves the timeout into the future.	2138	a new one that moves the timeout into the future.
1600		2139
1601	=head3 Results	2140	=head3 Results
1602		2141
1603	name sockets create request	2142	name sockets create request
1604	EV 20000 69.01 11.16	2143	EV 20000 69.01 11.16
1605	Perl 20000 73.32 35.87	2144	Perl 20000 73.32 35.87
		2145	IOAsync 20000 157.00 98.14 epoll
		2146	IOAsync 20000 159.31 616.06 poll
1606	Event 20000 212.62 257.32	2147	Event 20000 212.62 257.32
1607	Glib 20000 651.16 1896.30	2148	Glib 20000 651.16 1896.30
1608	POE 20000 349.67 12317.24 uses POE::Loop::Event	2149	POE 20000 349.67 12317.24 uses POE::Loop::Event
1609		2150
1610	=head3 Discussion	2151	=head3 Discussion
1611		2152
1612	This benchmark I<does> measure scalability and overall performance of the	2153	This benchmark I<does> measure scalability and overall performance of the
1613	particular event loop.	2154	particular event loop.
…		…
1615	EV is again fastest. Since it is using epoll on my system, the setup time	2156	EV is again fastest. Since it is using epoll on my system, the setup time
1616	is relatively high, though.	2157	is relatively high, though.
1617		2158
1618	Perl surprisingly comes second. It is much faster than the C-based event	2159	Perl surprisingly comes second. It is much faster than the C-based event
1619	loops Event and Glib.	2160	loops Event and Glib.
		2161
		2162	IO::Async performs very well when using its epoll backend, and still quite
		2163	good compared to Glib when using its pure perl backend.
1620		2164
1621	Event suffers from high setup time as well (look at its code and you will	2165	Event suffers from high setup time as well (look at its code and you will
1622	understand why). Callback invocation also has a high overhead compared to	2166	understand why). Callback invocation also has a high overhead compared to
1623	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2167	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1624	uses select or poll in basically all documented configurations.	2168	uses select or poll in basically all documented configurations.
…		…
1687	=item * C-based event loops perform very well with small number of	2231	=item * C-based event loops perform very well with small number of
1688	watchers, as the management overhead dominates.	2232	watchers, as the management overhead dominates.
1689		2233
1690	=back	2234	=back
1691		2235
		2236	=head2 THE IO::Lambda BENCHMARK
		2237
		2238	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2239	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2240	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2241	shouldn't come as a surprise to anybody). As such, the benchmark is
		2242	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2243	very optimal. But how would AnyEvent compare when used without the extra
		2244	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2245
		2246	The benchmark itself creates an echo-server, and then, for 500 times,
		2247	connects to the echo server, sends a line, waits for the reply, and then
		2248	creates the next connection. This is a rather bad benchmark, as it doesn't
		2249	test the efficiency of the framework or much non-blocking I/O, but it is a
		2250	benchmark nevertheless.
		2251
		2252	name runtime
		2253	Lambda/select 0.330 sec
		2254	+ optimized 0.122 sec
		2255	Lambda/AnyEvent 0.327 sec
		2256	+ optimized 0.138 sec
		2257	Raw sockets/select 0.077 sec
		2258	POE/select, components 0.662 sec
		2259	POE/select, raw sockets 0.226 sec
		2260	POE/select, optimized 0.404 sec
		2261
		2262	AnyEvent/select/nb 0.085 sec
		2263	AnyEvent/EV/nb 0.068 sec
		2264	+state machine 0.134 sec
		2265
		2266	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2267	benchmarks actually make blocking connects and use 100% blocking I/O,
		2268	defeating the purpose of an event-based solution. All of the newly
		2269	written AnyEvent benchmarks use 100% non-blocking connects (using
		2270	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2271	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2272	generally require a lot more bookkeeping and event handling than blocking
		2273	connects (which involve a single syscall only).
		2274
		2275	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2276	offers similar expressive power as POE and IO::Lambda, using conventional
		2277	Perl syntax. This means that both the echo server and the client are 100%
		2278	non-blocking, further placing it at a disadvantage.
		2279
		2280	As you can see, the AnyEvent + EV combination even beats the
		2281	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2282	backend easily beats IO::Lambda and POE.
		2283
		2284	And even the 100% non-blocking version written using the high-level (and
		2285	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2286	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2287	in a non-blocking way.
		2288
		2289	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2290	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2291	part of the IO::lambda distribution and were used without any changes.
		2292
		2293
		2294	=head1 SIGNALS
		2295
		2296	AnyEvent currently installs handlers for these signals:
		2297
		2298	=over 4
		2299
		2300	=item SIGCHLD
		2301
		2302	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2303	emulation for event loops that do not support them natively. Also, some
		2304	event loops install a similar handler.
		2305
		2306	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2307	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2308
		2309	=item SIGPIPE
		2310
		2311	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2312	when AnyEvent gets loaded.
		2313
		2314	The rationale for this is that AnyEvent users usually do not really depend
		2315	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2316	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2317	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2318	some random socket.
		2319
		2320	The rationale for installing a no-op handler as opposed to ignoring it is
		2321	that this way, the handler will be restored to defaults on exec.
		2322
		2323	Feel free to install your own handler, or reset it to defaults.
		2324
		2325	=back
		2326
		2327	=cut
		2328
		2329	undef $SIG{CHLD}
		2330	if $SIG{CHLD} eq 'IGNORE';
		2331
		2332	$SIG{PIPE} = sub { }
		2333	unless defined $SIG{PIPE};
		2334
		2335	=head1 RECOMMENDED/OPTIONAL MODULES
		2336
		2337	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2338	it's built-in modules) are required to use it.
		2339
		2340	That does not mean that AnyEvent won't take advantage of some additional
		2341	modules if they are installed.
		2342
		2343	This section epxlains which additional modules will be used, and how they
		2344	affect AnyEvent's operetion.
		2345
		2346	=over 4
		2347
		2348	=item L<Async::Interrupt>
		2349
		2350	This slightly arcane module is used to implement fast signal handling: To
		2351	my knowledge, there is no way to do completely race-free and quick
		2352	signal handling in pure perl. To ensure that signals still get
		2353	delivered, AnyEvent will start an interval timer to wake up perl (and
		2354	catch the signals) with some delay (default is 10 seconds, look for
		2355	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2356
		2357	If this module is available, then it will be used to implement signal
		2358	catching, which means that signals will not be delayed, and the event loop
		2359	will not be interrupted regularly, which is more efficient (And good for
		2360	battery life on laptops).
		2361
		2362	This affects not just the pure-perl event loop, but also other event loops
		2363	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2364
		2365	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2366	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2367	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2368	does nothing for those backends.
		2369
		2370	=item L<EV>
		2371
		2372	This module isn't really "optional", as it is simply one of the backend
		2373	event loops that AnyEvent can use. However, it is simply the best event
		2374	loop available in terms of features, speed and stability: It supports
		2375	the AnyEvent API optimally, implements all the watcher types in XS, does
		2376	automatic timer adjustments even when no monotonic clock is available,
		2377	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2378	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2379	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2380
		2381	=item L<Guard>
		2382
		2383	The guard module, when used, will be used to implement
		2384	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2385	lot less memory), but otherwise doesn't affect guard operation much. It is
		2386	purely used for performance.
		2387
		2388	=item L<JSON> and L<JSON::XS>
		2389
		2390	This module is required when you want to read or write JSON data via
		2391	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2392	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2393
		2394	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2395	installed.
		2396
		2397	=item L<Net::SSLeay>
		2398
		2399	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2400	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2401	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2402
		2403	=item L<Time::HiRes>
		2404
		2405	This module is part of perl since release 5.008. It will be used when the
		2406	chosen event library does not come with a timing source on it's own. The
		2407	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2408	try to use a monotonic clock for timing stability.
		2409
		2410	=back
		2411
1692		2412
1693	=head1 FORK	2413	=head1 FORK
1694		2414
1695	Most event libraries are not fork-safe. The ones who are usually are	2415	Most event libraries are not fork-safe. The ones who are usually are
1696	because they rely on inefficient but fork-safe C<select> or C<poll>	2416	because they rely on inefficient but fork-safe C<select> or C<poll>
1697	calls. Only L<EV> is fully fork-aware.	2417	calls. Only L<EV> is fully fork-aware.
1698		2418
1699	If you have to fork, you must either do so I<before> creating your first	2419	If you have to fork, you must either do so I<before> creating your first
1700	watcher OR you must not use AnyEvent at all in the child.	2420	watcher OR you must not use AnyEvent at all in the child OR you must do
		2421	something completely out of the scope of AnyEvent.
1701		2422
1702		2423
1703	=head1 SECURITY CONSIDERATIONS	2424	=head1 SECURITY CONSIDERATIONS
1704		2425
1705	AnyEvent can be forced to load any event model via	2426	AnyEvent can be forced to load any event model via
…		…
1717	use AnyEvent;	2438	use AnyEvent;
1718		2439
1719	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2440	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1720	be used to probe what backend is used and gain other information (which is	2441	be used to probe what backend is used and gain other information (which is
1721	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2442	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1722	$ENV{PERL_ANYEGENT_STRICT}.	2443	$ENV{PERL_ANYEVENT_STRICT}.
		2444
		2445	Note that AnyEvent will remove I<all> environment variables starting with
		2446	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2447	enabled.
1723		2448
1724		2449
1725	=head1 BUGS	2450	=head1 BUGS
1726		2451
1727	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2452	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1728	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2453	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1729	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2454	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1730	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2455	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1731	pronounced).	2456	pronounced).
1732		2457
1733		2458
1734	=head1 SEE ALSO	2459	=head1 SEE ALSO
1735		2460
…		…
1739	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2464	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1740		2465
1741	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2466	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1742	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2467	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1743	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2468	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1744	L<AnyEvent::Impl::POE>.	2469	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1745		2470
1746	Non-blocking file handles, sockets, TCP clients and	2471	Non-blocking file handles, sockets, TCP clients and
1747	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2472	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1748		2473
1749	Asynchronous DNS: L<AnyEvent::DNS>.	2474	Asynchronous DNS: L<AnyEvent::DNS>.
1750		2475
1751	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2476	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2477	L<Coro::Event>,
1752		2478
1753	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2479	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2480	L<AnyEvent::HTTP>.
1754		2481
1755		2482
1756	=head1 AUTHOR	2483	=head1 AUTHOR
1757		2484
1758	Marc Lehmann <schmorp@schmorp.de>	2485	Marc Lehmann <schmorp@schmorp.de>

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