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Revision 1.170 by root, Wed Jul 9 11:53:40 2008 UTC vs.
Revision 1.239 by root, Thu Jul 16 20:55:38 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
22		39
23	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
24		41
25	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
…		…
128	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
129	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
130	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
131	is in control).	148	is in control).
132		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
133	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
134	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
135	to it).	158	to it).
136		159
137	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
153	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
154		177
155	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
156	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
157		180
158	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	181	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
159	(AnyEvent might or might not keep a reference to this file handle). C<poll>	182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
160	must be a string that is either C<r> or C<w>, which creates a watcher	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
161	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
162	callback to invoke each time the file handle becomes ready.	191	C<cb> is the callback to invoke each time the file handle becomes ready.
163		192
164	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
165	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
166	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
167		196
…		…
299	In either case, if you care (and in most cases, you don't), then you	328	In either case, if you care (and in most cases, you don't), then you
300	can get whatever behaviour you want with any event loop, by taking the	329	can get whatever behaviour you want with any event loop, by taking the
301	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
302	account.	331	account.
303		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
304	=back	348	=back
305		349
306	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
307		351
308	You can watch for signals using a signal watcher, C<signal> is the signal	352	You can watch for signals using a signal watcher, C<signal> is the signal
…		…
331	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
332		376
333	You can also watch on a child process exit and catch its exit status.	377	You can also watch on a child process exit and catch its exit status.
334		378
335	The child process is specified by the C<pid> argument (if set to C<0>, it	379	The child process is specified by the C<pid> argument (if set to C<0>, it
336	watches for any child process exit). The watcher will trigger as often	380	watches for any child process exit). The watcher will triggered only when
337	as status change for the child are received. This works by installing a	381	the child process has finished and an exit status is available, not on
338	signal handler for C<SIGCHLD>. The callback will be called with the pid	382	any trace events (stopped/continued).
339	and exit status (as returned by waitpid), so unlike other watcher types,	383
340	you I<can> rely on child watcher callback arguments.	384	The callback will be called with the pid and exit status (as returned by
		385	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		386	callback arguments.
		387
		388	This watcher type works by installing a signal handler for C<SIGCHLD>,
		389	and since it cannot be shared, nothing else should use SIGCHLD or reap
		390	random child processes (waiting for specific child processes, e.g. inside
		391	C<system>, is just fine).
341		392
342	There is a slight catch to child watchers, however: you usually start them	393	There is a slight catch to child watchers, however: you usually start them
343	I<after> the child process was created, and this means the process could	394	I<after> the child process was created, and this means the process could
344	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
345		396
346	Not all event models handle this correctly (POE doesn't), but even for	397	Not all event models handle this correctly (neither POE nor IO::Async do,
		398	see their AnyEvent::Impl manpages for details), but even for event models
347	event models that I<do> handle this correctly, they usually need to be	399	that I<do> handle this correctly, they usually need to be loaded before
348	loaded before the process exits (i.e. before you fork in the first place).	400	the process exits (i.e. before you fork in the first place). AnyEvent's
		401	pure perl event loop handles all cases correctly regardless of when you
		402	start the watcher.
349		403
350	This means you cannot create a child watcher as the very first thing in an	404	This means you cannot create a child watcher as the very first
351	AnyEvent program, you I<have> to create at least one watcher before you	405	thing in an AnyEvent program, you I<have> to create at least one
352	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	406	watcher before you C<fork> the child (alternatively, you can call
		407	C<AnyEvent::detect>).
353		408
354	Example: fork a process and wait for it	409	Example: fork a process and wait for it
355		410
356	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
357		412
…		…
367	);	422	);
368		423
369	# do something else, then wait for process exit	424	# do something else, then wait for process exit
370	$done->recv;	425	$done->recv;
371		426
		427	=head2 IDLE WATCHERS
		428
		429	Sometimes there is a need to do something, but it is not so important
		430	to do it instantly, but only when there is nothing better to do. This
		431	"nothing better to do" is usually defined to be "no other events need
		432	attention by the event loop".
		433
		434	Idle watchers ideally get invoked when the event loop has nothing
		435	better to do, just before it would block the process to wait for new
		436	events. Instead of blocking, the idle watcher is invoked.
		437
		438	Most event loops unfortunately do not really support idle watchers (only
		439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		440	will simply call the callback "from time to time".
		441
		442	Example: read lines from STDIN, but only process them when the
		443	program is otherwise idle:
		444
		445	my @lines; # read data
		446	my $idle_w;
		447	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		448	push @lines, scalar <STDIN>;
		449
		450	# start an idle watcher, if not already done
		451	$idle_w ||= AnyEvent->idle (cb => sub {
		452	# handle only one line, when there are lines left
		453	if (my $line = shift @lines) {
		454	print "handled when idle: $line";
		455	} else {
		456	# otherwise disable the idle watcher again
		457	undef $idle_w;
		458	}
		459	});
		460	});
		461
372	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
373		463
374	If you are familiar with some event loops you will know that all of them	464	If you are familiar with some event loops you will know that all of them
375	require you to run some blocking "loop", "run" or similar function that	465	require you to run some blocking "loop", "run" or similar function that
376	will actively watch for new events and call your callbacks.	466	will actively watch for new events and call your callbacks.
377		467
378	AnyEvent is different, it expects somebody else to run the event loop and	468	AnyEvent is slightly different: it expects somebody else to run the event
379	will only block when necessary (usually when told by the user).	469	loop and will only block when necessary (usually when told by the user).
380		470
381	The instrument to do that is called a "condition variable", so called	471	The instrument to do that is called a "condition variable", so called
382	because they represent a condition that must become true.	472	because they represent a condition that must become true.
		473
		474	Now is probably a good time to look at the examples further below.
383		475
384	Condition variables can be created by calling the C<< AnyEvent->condvar	476	Condition variables can be created by calling the C<< AnyEvent->condvar
385	>> method, usually without arguments. The only argument pair allowed is	477	>> method, usually without arguments. The only argument pair allowed is
386	C<cb>, which specifies a callback to be called when the condition variable	478	C<cb>, which specifies a callback to be called when the condition variable
387	becomes true.	479	becomes true, with the condition variable as the first argument (but not
		480	the results).
388		481
389	After creation, the condition variable is "false" until it becomes "true"	482	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	483	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<<	484	were a callback, read about the caveats in the description for the C<<
392	->send >> method).	485	->send >> method).
…		…
438	after => 1,	531	after => 1,
439	cb => sub { $result_ready->send },	532	cb => sub { $result_ready->send },
440	);	533	);
441		534
442	# this "blocks" (while handling events) till the callback	535	# this "blocks" (while handling events) till the callback
443	# calls send	536	# calls -<send
444	$result_ready->recv;	537	$result_ready->recv;
445		538
446	Example: wait for a timer, but take advantage of the fact that	539	Example: wait for a timer, but take advantage of the fact that condition
447	condition variables are also code references.	540	variables are also callable directly.
448		541
449	my $done = AnyEvent->condvar;	542	my $done = AnyEvent->condvar;
450	my $delay = AnyEvent->timer (after => 5, cb => $done);	543	my $delay = AnyEvent->timer (after => 5, cb => $done);
451	$done->recv;	544	$done->recv;
		545
		546	Example: Imagine an API that returns a condvar and doesn't support
		547	callbacks. This is how you make a synchronous call, for example from
		548	the main program:
		549
		550	use AnyEvent::CouchDB;
		551
		552	...
		553
		554	my @info = $couchdb->info->recv;
		555
		556	And this is how you would just set a callback to be called whenever the
		557	results are available:
		558
		559	$couchdb->info->cb (sub {
		560	my @info = $_[0]->recv;
		561	});
452		562
453	=head3 METHODS FOR PRODUCERS	563	=head3 METHODS FOR PRODUCERS
454		564
455	These methods should only be used by the producing side, i.e. the	565	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	566	code/module that eventually sends the signal. Note that it is also
…		…
469	immediately from within send.	579	immediately from within send.
470		580
471	Any arguments passed to the C<send> call will be returned by all	581	Any arguments passed to the C<send> call will be returned by all
472	future C<< ->recv >> calls.	582	future C<< ->recv >> calls.
473		583
474	Condition variables are overloaded so one can call them directly	584	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	585	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	586	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		587
483	=item $cv->croak ($error)	588	=item $cv->croak ($error)
484		589
485	Similar to send, but causes all call's to C<< ->recv >> to invoke	590	Similar to send, but causes all call's to C<< ->recv >> to invoke
486	C<Carp::croak> with the given error message/object/scalar.	591	C<Carp::croak> with the given error message/object/scalar.
487		592
488	This can be used to signal any errors to the condition variable	593	This can be used to signal any errors to the condition variable
489	user/consumer.	594	user/consumer. Doing it this way instead of calling C<croak> directly
		595	delays the error detetcion, but has the overwhelmign advantage that it
		596	diagnoses the error at the place where the result is expected, and not
		597	deep in some event clalback without connection to the actual code causing
		598	the problem.
490		599
491	=item $cv->begin ([group callback])	600	=item $cv->begin ([group callback])
492		601
493	=item $cv->end	602	=item $cv->end
494
495	These two methods are EXPERIMENTAL and MIGHT CHANGE.
496		603
497	These two methods can be used to combine many transactions/events into	604	These two methods can be used to combine many transactions/events into
498	one. For example, a function that pings many hosts in parallel might want	605	one. For example, a function that pings many hosts in parallel might want
499	to use a condition variable for the whole process.	606	to use a condition variable for the whole process.
500		607
…		…
502	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	609	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
503	>>, the (last) callback passed to C<begin> will be executed. That callback	610	>>, the (last) callback passed to C<begin> will be executed. That callback
504	is I<supposed> to call C<< ->send >>, but that is not required. If no	611	is I<supposed> to call C<< ->send >>, but that is not required. If no
505	callback was set, C<send> will be called without any arguments.	612	callback was set, C<send> will be called without any arguments.
506		613
507	Let's clarify this with the ping example:	614	You can think of C<< $cv->send >> giving you an OR condition (one call
		615	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		616	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		617
		618	Let's start with a simple example: you have two I/O watchers (for example,
		619	STDOUT and STDERR for a program), and you want to wait for both streams to
		620	close before activating a condvar:
		621
		622	my $cv = AnyEvent->condvar;
		623
		624	$cv->begin; # first watcher
		625	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		626	defined sysread $fh1, my $buf, 4096
		627	or $cv->end;
		628	});
		629
		630	$cv->begin; # second watcher
		631	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		632	defined sysread $fh2, my $buf, 4096
		633	or $cv->end;
		634	});
		635
		636	$cv->recv;
		637
		638	This works because for every event source (EOF on file handle), there is
		639	one call to C<begin>, so the condvar waits for all calls to C<end> before
		640	sending.
		641
		642	The ping example mentioned above is slightly more complicated, as the
		643	there are results to be passwd back, and the number of tasks that are
		644	begung can potentially be zero:
508		645
509	my $cv = AnyEvent->condvar;	646	my $cv = AnyEvent->condvar;
510		647
511	my %result;	648	my %result;
512	$cv->begin (sub { $cv->send (\%result) });	649	$cv->begin (sub { $cv->send (\%result) });
…		…
532	loop, which serves two important purposes: first, it sets the callback	669	loop, which serves two important purposes: first, it sets the callback
533	to be called once the counter reaches C<0>, and second, it ensures that	670	to be called once the counter reaches C<0>, and second, it ensures that
534	C<send> is called even when C<no> hosts are being pinged (the loop	671	C<send> is called even when C<no> hosts are being pinged (the loop
535	doesn't execute once).	672	doesn't execute once).
536		673
537	This is the general pattern when you "fan out" into multiple subrequests:	674	This is the general pattern when you "fan out" into multiple (but
538	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	675	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
539	is called at least once, and then, for each subrequest you start, call	676	the callback and ensure C<end> is called at least once, and then, for each
540	C<begin> and for each subrequest you finish, call C<end>.	677	subrequest you start, call C<begin> and for each subrequest you finish,
		678	call C<end>.
541		679
542	=back	680	=back
543		681
544	=head3 METHODS FOR CONSUMERS	682	=head3 METHODS FOR CONSUMERS
545		683
…		…
561	function will call C<croak>.	699	function will call C<croak>.
562		700
563	In list context, all parameters passed to C<send> will be returned,	701	In list context, all parameters passed to C<send> will be returned,
564	in scalar context only the first one will be returned.	702	in scalar context only the first one will be returned.
565		703
		704	Note that doing a blocking wait in a callback is not supported by any
		705	event loop, that is, recursive invocation of a blocking C<< ->recv
		706	>> is not allowed, and the C<recv> call will C<croak> if such a
		707	condition is detected. This condition can be slightly loosened by using
		708	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		709	any thread that doesn't run the event loop itself.
		710
566	Not all event models support a blocking wait - some die in that case	711	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	712	(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	713	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	714	caller decide whether the call will block or not (for example, by coupling
570	condition variables with some kind of request results and supporting	715	condition variables with some kind of request results and supporting
571	callbacks so the caller knows that getting the result will not block,	716	callbacks so the caller knows that getting the result will not block,
572	while still supporting blocking waits if the caller so desires).	717	while still supporting blocking waits if the caller so desires).
573		718
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	719	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	720	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	721	time). This will work even when the event loop does not support blocking
588	waits otherwise.	722	waits otherwise.
589		723
590	=item $bool = $cv->ready	724	=item $bool = $cv->ready
591		725
592	Returns true when the condition is "true", i.e. whether C<send> or	726	Returns true when the condition is "true", i.e. whether C<send> or
593	C<croak> have been called.	727	C<croak> have been called.
594		728
595	=item $cb = $cv->cb ([new callback])	729	=item $cb = $cv->cb ($cb->($cv))
596		730
597	This is a mutator function that returns the callback set and optionally	731	This is a mutator function that returns the callback set and optionally
598	replaces it before doing so.	732	replaces it before doing so.
599		733
600	The callback will be called when the condition becomes "true", i.e. when	734	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	736	variable itself. Calling C<recv> inside the callback or at any later time
603	is guaranteed not to block.	737	is guaranteed not to block.
604		738
605	=back	739	=back
606		740
		741	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		742
		743	The available backend classes are (every class has its own manpage):
		744
		745	=over 4
		746
		747	=item Backends that are autoprobed when no other event loop can be found.
		748
		749	EV is the preferred backend when no other event loop seems to be in
		750	use. If EV is not installed, then AnyEvent will try Event, and, failing
		751	that, will fall back to its own pure-perl implementation, which is
		752	available everywhere as it comes with AnyEvent itself.
		753
		754	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		755	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		756	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		757
		758	=item Backends that are transparently being picked up when they are used.
		759
		760	These will be used when they are currently loaded when the first watcher
		761	is created, in which case it is assumed that the application is using
		762	them. This means that AnyEvent will automatically pick the right backend
		763	when the main program loads an event module before anything starts to
		764	create watchers. Nothing special needs to be done by the main program.
		765
		766	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		767	AnyEvent::Impl::Tk based on Tk, very broken.
		768	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		769	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		770
		771	=item Backends with special needs.
		772
		773	Qt requires the Qt::Application to be instantiated first, but will
		774	otherwise be picked up automatically. As long as the main program
		775	instantiates the application before any AnyEvent watchers are created,
		776	everything should just work.
		777
		778	AnyEvent::Impl::Qt based on Qt.
		779
		780	Support for IO::Async can only be partial, as it is too broken and
		781	architecturally limited to even support the AnyEvent API. It also
		782	is the only event loop that needs the loop to be set explicitly, so
		783	it can only be used by a main program knowing about AnyEvent. See
		784	L<AnyEvent::Impl::Async> for the gory details.
		785
		786	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		787
		788	=item Event loops that are indirectly supported via other backends.
		789
		790	Some event loops can be supported via other modules:
		791
		792	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		793
		794	B<WxWidgets> has no support for watching file handles. However, you can
		795	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		796	polls 20 times per second, which was considered to be too horrible to even
		797	consider for AnyEvent.
		798
		799	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		800	backend, so it can be supported through POE.
		801
		802	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		803	load L<POE> when detecting them, in the hope that POE will pick them up,
		804	in which case everything will be automatic.
		805
		806	=back
		807
607	=head1 GLOBAL VARIABLES AND FUNCTIONS	808	=head1 GLOBAL VARIABLES AND FUNCTIONS
608		809
		810	These are not normally required to use AnyEvent, but can be useful to
		811	write AnyEvent extension modules.
		812
609	=over 4	813	=over 4
610		814
611	=item $AnyEvent::MODEL	815	=item $AnyEvent::MODEL
612		816
613	Contains C<undef> until the first watcher is being created. Then it	817	Contains C<undef> until the first watcher is being created, before the
		818	backend has been autodetected.
		819
614	contains the event model that is being used, which is the name of the	820	Afterwards it contains the event model that is being used, which is the
615	Perl class implementing the model. This class is usually one of the	821	name of the Perl class implementing the model. This class is usually one
616	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	822	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
617	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	823	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
618		824	will be C<urxvt::anyevent>).
619	The known classes so far are:
620
621	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
622	AnyEvent::Impl::Event based on Event, second best choice.
623	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
624	AnyEvent::Impl::Glib based on Glib, third-best choice.
625	AnyEvent::Impl::Tk based on Tk, very bad choice.
626	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
627	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
628	AnyEvent::Impl::POE based on POE, not generic enough for full support.
629
630	There is no support for WxWidgets, as WxWidgets has no support for
631	watching file handles. However, you can use WxWidgets through the
632	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
633	second, which was considered to be too horrible to even consider for
634	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
635	it's adaptor.
636
637	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
638	autodetecting them.
639		825
640	=item AnyEvent::detect	826	=item AnyEvent::detect
641		827
642	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	828	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
643	if necessary. You should only call this function right before you would	829	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	830	have created an AnyEvent watcher anyway, that is, as late as possible at
645	runtime.	831	runtime, and not e.g. while initialising of your module.
		832
		833	If you need to do some initialisation before AnyEvent watchers are
		834	created, use C<post_detect>.
646		835
647	=item $guard = AnyEvent::post_detect { BLOCK }	836	=item $guard = AnyEvent::post_detect { BLOCK }
648		837
649	Arranges for the code block to be executed as soon as the event model is	838	Arranges for the code block to be executed as soon as the event model is
650	autodetected (or immediately if this has already happened).	839	autodetected (or immediately if this has already happened).
		840
		841	The block will be executed I<after> the actual backend has been detected
		842	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		843	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		844	other initialisations - see the sources of L<AnyEvent::Strict> or
		845	L<AnyEvent::AIO> to see how this is used.
		846
		847	The most common usage is to create some global watchers, without forcing
		848	event module detection too early, for example, L<AnyEvent::AIO> creates
		849	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		850	avoid autodetecting the event module at load time.
651		851
652	If called in scalar or list context, then it creates and returns an object	852	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	853	that automatically removes the callback again when it is destroyed. See
654	L<Coro::BDB> for a case where this is useful.	854	L<Coro::BDB> for a case where this is useful.
655		855
…		…
658	If there are any code references in this array (you can C<push> to it	858	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	859	before or after loading AnyEvent), then they will called directly after
660	the event loop has been chosen.	860	the event loop has been chosen.
661		861
662	You should check C<$AnyEvent::MODEL> before adding to this array, though:	862	You should check C<$AnyEvent::MODEL> before adding to this array, though:
663	if it contains a true value then the event loop has already been detected,	863	if it is defined then the event loop has already been detected, and the
664	and the array will be ignored.	864	array will be ignored.
665		865
666	Best use C<AnyEvent::post_detect { BLOCK }> instead.	866	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		867	it,as it takes care of these details.
		868
		869	This variable is mainly useful for modules that can do something useful
		870	when AnyEvent is used and thus want to know when it is initialised, but do
		871	not need to even load it by default. This array provides the means to hook
		872	into AnyEvent passively, without loading it.
667		873
668	=back	874	=back
669		875
670	=head1 WHAT TO DO IN A MODULE	876	=head1 WHAT TO DO IN A MODULE
671		877
…		…
726		932
727		933
728	=head1 OTHER MODULES	934	=head1 OTHER MODULES
729		935
730	The following is a non-exhaustive list of additional modules that use	936	The following is a non-exhaustive list of additional modules that use
731	AnyEvent and can therefore be mixed easily with other AnyEvent modules	937	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	938	modules and other event loops in the same program. Some of the modules
733	available via CPAN.	939	come with AnyEvent, most are available via CPAN.
734		940
735	=over 4	941	=over 4
736		942
737	=item L<AnyEvent::Util>	943	=item L<AnyEvent::Util>
738		944
…		…
747		953
748	=item L<AnyEvent::Handle>	954	=item L<AnyEvent::Handle>
749		955
750	Provide read and write buffers, manages watchers for reads and writes,	956	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	957	supports raw and formatted I/O, I/O queued and fully transparent and
752	non-blocking SSL/TLS.	958	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
753		959
754	=item L<AnyEvent::DNS>	960	=item L<AnyEvent::DNS>
755		961
756	Provides rich asynchronous DNS resolver capabilities.	962	Provides rich asynchronous DNS resolver capabilities.
757		963
…		…
785		991
786	=item L<AnyEvent::GPSD>	992	=item L<AnyEvent::GPSD>
787		993
788	A non-blocking interface to gpsd, a daemon delivering GPS information.	994	A non-blocking interface to gpsd, a daemon delivering GPS information.
789		995
		996	=item L<AnyEvent::IRC>
		997
		998	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		999
		1000	=item L<AnyEvent::XMPP>
		1001
		1002	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1003	Net::XMPP2>.
		1004
790	=item L<AnyEvent::IGS>	1005	=item L<AnyEvent::IGS>
791		1006
792	A non-blocking interface to the Internet Go Server protocol (used by	1007	A non-blocking interface to the Internet Go Server protocol (used by
793	L<App::IGS>).	1008	L<App::IGS>).
794		1009
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>	1010	=item L<Net::FCP>
804		1011
805	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1012	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
806	of AnyEvent.	1013	of AnyEvent.
807		1014
…		…
811		1018
812	=item L<Coro>	1019	=item L<Coro>
813		1020
814	Has special support for AnyEvent via L<Coro::AnyEvent>.	1021	Has special support for AnyEvent via L<Coro::AnyEvent>.
815		1022
816	=item L<IO::Lambda>
817
818	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
819
820	=back	1023	=back
821		1024
822	=cut	1025	=cut
823		1026
824	package AnyEvent;	1027	package AnyEvent;
825		1028
826	no warnings;	1029	no warnings;
827	use strict;	1030	use strict qw(vars subs);
828		1031
829	use Carp;	1032	use Carp ();
830		1033
831	our $VERSION = 4.2;	1034	our $VERSION = 4.82;
832	our $MODEL;	1035	our $MODEL;
833		1036
834	our $AUTOLOAD;	1037	our $AUTOLOAD;
835	our @ISA;	1038	our @ISA;
836		1039
837	our @REGISTRY;	1040	our @REGISTRY;
838		1041
839	our $WIN32;	1042	our $WIN32;
840		1043
841	BEGIN {	1044	BEGIN {
842	my $win32 = ! ! ($^O =~ /mswin32/i);	1045	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
843	eval "sub WIN32(){ $win32 }";	1046	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1047
		1048	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1049	if ${^TAINT};
844	}	1050	}
845		1051
846	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1052	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
847		1053
848	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1054	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
…		…
859	[Event:: => AnyEvent::Impl::Event::],	1065	[Event:: => AnyEvent::Impl::Event::],
860	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1066	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
861	# everything below here will not be autoprobed	1067	# everything below here will not be autoprobed
862	# as the pureperl backend should work everywhere	1068	# as the pureperl backend should work everywhere
863	# and is usually faster	1069	# and is usually faster
864	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
865	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1070	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
866	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1071	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1072	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
867	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1073	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
868	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1074	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
869	[Wx:: => AnyEvent::Impl::POE::],	1075	[Wx:: => AnyEvent::Impl::POE::],
870	[Prima:: => AnyEvent::Impl::POE::],	1076	[Prima:: => AnyEvent::Impl::POE::],
		1077	# IO::Async is just too broken - we would need workarounds for its
		1078	# byzantine signal and broken child handling, among others.
		1079	# IO::Async is rather hard to detect, as it doesn't have any
		1080	# obvious default class.
		1081	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1082	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1083	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
871	);	1084	);
872		1085
873	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1086	our %method = map +($_ => 1),
		1087	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
874		1088
875	our @post_detect;	1089	our @post_detect;
876		1090
877	sub post_detect(&) {	1091	sub post_detect(&) {
878	my ($cb) = @_;	1092	my ($cb) = @_;
…		…
883	1	1097	1
884	} else {	1098	} else {
885	push @post_detect, $cb;	1099	push @post_detect, $cb;
886		1100
887	defined wantarray	1101	defined wantarray
888	? bless \$cb, "AnyEvent::Util::PostDetect"	1102	? bless \$cb, "AnyEvent::Util::postdetect"
889	: ()	1103	: ()
890	}	1104	}
891	}	1105	}
892		1106
893	sub AnyEvent::Util::PostDetect::DESTROY {	1107	sub AnyEvent::Util::postdetect::DESTROY {
894	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1108	@post_detect = grep $_ != ${$_[0]}, @post_detect;
895	}	1109	}
896		1110
897	sub detect() {	1111	sub detect() {
898	unless ($MODEL) {	1112	unless ($MODEL) {
…		…
901		1115
902	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1116	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
903	my $model = "AnyEvent::Impl::$1";	1117	my $model = "AnyEvent::Impl::$1";
904	if (eval "require $model") {	1118	if (eval "require $model") {
905	$MODEL = $model;	1119	$MODEL = $model;
906	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1120	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $verbose > 1;
907	} else {	1121	} else {
908	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1122	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $verbose;
909	}	1123	}
910	}	1124	}
911		1125
912	# check for already loaded models	1126	# check for already loaded models
913	unless ($MODEL) {	1127	unless ($MODEL) {
…		…
935	last;	1149	last;
936	}	1150	}
937	}	1151	}
938		1152
939	$MODEL	1153	$MODEL
940	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1154	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
941	}	1155	}
942	}	1156	}
943		1157
944	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1158	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
945		1159
…		…
955		1169
956	sub AUTOLOAD {	1170	sub AUTOLOAD {
957	(my $func = $AUTOLOAD) =~ s/.*://;	1171	(my $func = $AUTOLOAD) =~ s/.*://;
958		1172
959	$method{$func}	1173	$method{$func}
960	or croak "$func: not a valid method for AnyEvent objects";	1174	or Carp::croak "$func: not a valid method for AnyEvent objects";
961		1175
962	detect unless $MODEL;	1176	detect unless $MODEL;
963		1177
964	my $class = shift;	1178	my $class = shift;
965	$class->$func (@_);	1179	$class->$func (@_);
966	}	1180	}
967		1181
968	# utility function to dup a filehandle. this is used by many backends	1182	# utility function to dup a filehandle. this is used by many backends
969	# to support binding more than one watcher per filehandle (they usually	1183	# 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).	1184	# allow only one watcher per fd, so we dup it to get a different one).
971	sub _dupfh($$$$) {	1185	sub _dupfh($$;$$) {
972	my ($poll, $fh, $r, $w) = @_;	1186	my ($poll, $fh, $r, $w) = @_;
973		1187
974	require Fcntl;
975
976	# cygwin requires the fh mode to be matching, unix doesn't	1188	# cygwin requires the fh mode to be matching, unix doesn't
977	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1189	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		1190
981	open my $fh2, "$mode&" . fileno $fh	1191	open my $fh2, "$mode&", $fh
982	or die "cannot dup() filehandle: $!";	1192	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
983		1193
984	# we assume CLOEXEC is already set by perl in all important cases	1194	# we assume CLOEXEC is already set by perl in all important cases
985		1195
986	($fh2, $rw)	1196	($fh2, $rw)
987	}	1197	}
988		1198
989	package AnyEvent::Base;	1199	package AnyEvent::Base;
990		1200
991	# default implementation for now and time	1201	# default implementations for many methods
992		1202
993	use Time::HiRes ();	1203	BEGIN {
		1204	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1205	*_time = \&Time::HiRes::time;
		1206	# if (eval "use POSIX (); (POSIX::times())...
		1207	} else {
		1208	*_time = sub { time }; # epic fail
		1209	}
		1210	}
994		1211
995	sub time { Time::HiRes::time }	1212	sub time { _time }
996	sub now { Time::HiRes::time }	1213	sub now { _time }
		1214	sub now_update { }
997		1215
998	# default implementation for ->condvar	1216	# default implementation for ->condvar
999		1217
1000	sub condvar {	1218	sub condvar {
1001	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1219	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1002	}	1220	}
1003		1221
1004	# default implementation for ->signal	1222	# default implementation for ->signal
1005		1223
1006	our %SIG_CB;	1224	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1225
		1226	sub _signal_exec {
		1227	sysread $SIGPIPE_R, my $dummy, 4;
		1228
		1229	while (%SIG_EV) {
		1230	for (keys %SIG_EV) {
		1231	delete $SIG_EV{$_};
		1232	$_->() for values %{ $SIG_CB{$_} || {} };
		1233	}
		1234	}
		1235	}
1007		1236
1008	sub signal {	1237	sub signal {
1009	my (undef, %arg) = @_;	1238	my (undef, %arg) = @_;
1010		1239
		1240	unless ($SIGPIPE_R) {
		1241	require Fcntl;
		1242
		1243	if (AnyEvent::WIN32) {
		1244	require AnyEvent::Util;
		1245
		1246	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1247	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1248	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1249	} else {
		1250	pipe $SIGPIPE_R, $SIGPIPE_W;
		1251	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1252	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1253
		1254	# not strictly required, as $^F is normally 2, but let's make sure...
		1255	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1256	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1257	}
		1258
		1259	$SIGPIPE_R
		1260	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1261
		1262	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1263	}
		1264
1011	my $signal = uc $arg{signal}	1265	my $signal = uc $arg{signal}
1012	or Carp::croak "required option 'signal' is missing";	1266	or Carp::croak "required option 'signal' is missing";
1013		1267
1014	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1268	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1015	$SIG{$signal} ||= sub {	1269	$SIG{$signal} ||= sub {
1016	$_->() for values %{ $SIG_CB{$signal} || {} };	1270	local $!;
		1271	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1272	undef $SIG_EV{$signal};
1017	};	1273	};
1018		1274
1019	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1275	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1020	}	1276	}
1021		1277
1022	sub AnyEvent::Base::Signal::DESTROY {	1278	sub AnyEvent::Base::signal::DESTROY {
1023	my ($signal, $cb) = @{$_[0]};	1279	my ($signal, $cb) = @{$_[0]};
1024		1280
1025	delete $SIG_CB{$signal}{$cb};	1281	delete $SIG_CB{$signal}{$cb};
1026		1282
		1283	# delete doesn't work with older perls - they then
		1284	# print weird messages, or just unconditionally exit
		1285	# instead of getting the default action.
1027	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1286	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1028	}	1287	}
1029		1288
1030	# default implementation for ->child	1289	# default implementation for ->child
1031		1290
1032	our %PID_CB;	1291	our %PID_CB;
1033	our $CHLD_W;	1292	our $CHLD_W;
1034	our $CHLD_DELAY_W;	1293	our $CHLD_DELAY_W;
1035	our $PID_IDLE;
1036	our $WNOHANG;	1294	our $WNOHANG;
1037		1295
1038	sub _child_wait {	1296	sub _sigchld {
1039	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1297	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
1040	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1298	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
1041	(values %{ $PID_CB{0} || {} });	1299	(values %{ $PID_CB{0} || {} });
1042	}	1300	}
1043
1044	undef $PID_IDLE;
1045	}
1046
1047	sub _sigchld {
1048	# make sure we deliver these changes "synchronous" with the event loop.
1049	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1050	undef $CHLD_DELAY_W;
1051	&_child_wait;
1052	});
1053	}	1301	}
1054		1302
1055	sub child {	1303	sub child {
1056	my (undef, %arg) = @_;	1304	my (undef, %arg) = @_;
1057		1305
1058	defined (my $pid = $arg{pid} + 0)	1306	defined (my $pid = $arg{pid} + 0)
1059	or Carp::croak "required option 'pid' is missing";	1307	or Carp::croak "required option 'pid' is missing";
1060		1308
1061	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1309	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1062		1310
1063	unless ($WNOHANG) {
1064	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1311	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1065	}
1066		1312
1067	unless ($CHLD_W) {	1313	unless ($CHLD_W) {
1068	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1314	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1069	# child could be a zombie already, so make at least one round	1315	# child could be a zombie already, so make at least one round
1070	&_sigchld;	1316	&_sigchld;
1071	}	1317	}
1072		1318
1073	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1319	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1074	}	1320	}
1075		1321
1076	sub AnyEvent::Base::Child::DESTROY {	1322	sub AnyEvent::Base::child::DESTROY {
1077	my ($pid, $cb) = @{$_[0]};	1323	my ($pid, $cb) = @{$_[0]};
1078		1324
1079	delete $PID_CB{$pid}{$cb};	1325	delete $PID_CB{$pid}{$cb};
1080	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1326	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1081		1327
1082	undef $CHLD_W unless keys %PID_CB;	1328	undef $CHLD_W unless keys %PID_CB;
		1329	}
		1330
		1331	# idle emulation is done by simply using a timer, regardless
		1332	# of whether the process is idle or not, and not letting
		1333	# the callback use more than 50% of the time.
		1334	sub idle {
		1335	my (undef, %arg) = @_;
		1336
		1337	my ($cb, $w, $rcb) = $arg{cb};
		1338
		1339	$rcb = sub {
		1340	if ($cb) {
		1341	$w = _time;
		1342	&$cb;
		1343	$w = _time - $w;
		1344
		1345	# never use more then 50% of the time for the idle watcher,
		1346	# within some limits
		1347	$w = 0.0001 if $w < 0.0001;
		1348	$w = 5 if $w > 5;
		1349
		1350	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1351	} else {
		1352	# clean up...
		1353	undef $w;
		1354	undef $rcb;
		1355	}
		1356	};
		1357
		1358	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1359
		1360	bless \\$cb, "AnyEvent::Base::idle"
		1361	}
		1362
		1363	sub AnyEvent::Base::idle::DESTROY {
		1364	undef $${$_[0]};
1083	}	1365	}
1084		1366
1085	package AnyEvent::CondVar;	1367	package AnyEvent::CondVar;
1086		1368
1087	our @ISA = AnyEvent::CondVar::Base::;	1369	our @ISA = AnyEvent::CondVar::Base::;
…		…
1089	package AnyEvent::CondVar::Base;	1371	package AnyEvent::CondVar::Base;
1090		1372
1091	use overload	1373	use overload
1092	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1374	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1093	fallback => 1;	1375	fallback => 1;
		1376
		1377	our $WAITING;
1094		1378
1095	sub _send {	1379	sub _send {
1096	# nop	1380	# nop
1097	}	1381	}
1098		1382
…		…
1111	sub ready {	1395	sub ready {
1112	$_[0]{_ae_sent}	1396	$_[0]{_ae_sent}
1113	}	1397	}
1114		1398
1115	sub _wait {	1399	sub _wait {
		1400	$WAITING
		1401	and !$_[0]{_ae_sent}
		1402	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1403
		1404	local $WAITING = 1;
1116	AnyEvent->one_event while !$_[0]{_ae_sent};	1405	AnyEvent->one_event while !$_[0]{_ae_sent};
1117	}	1406	}
1118		1407
1119	sub recv {	1408	sub recv {
1120	$_[0]->_wait;	1409	$_[0]->_wait;
…		…
1139	}	1428	}
1140		1429
1141	# undocumented/compatibility with pre-3.4	1430	# undocumented/compatibility with pre-3.4
1142	*broadcast = \&send;	1431	*broadcast = \&send;
1143	*wait = \&_wait;	1432	*wait = \&_wait;
		1433
		1434	=head1 ERROR AND EXCEPTION HANDLING
		1435
		1436	In general, AnyEvent does not do any error handling - it relies on the
		1437	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1438	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1439	checking of all AnyEvent methods, however, which is highly useful during
		1440	development.
		1441
		1442	As for exception handling (i.e. runtime errors and exceptions thrown while
		1443	executing a callback), this is not only highly event-loop specific, but
		1444	also not in any way wrapped by this module, as this is the job of the main
		1445	program.
		1446
		1447	The pure perl event loop simply re-throws the exception (usually
		1448	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1449	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1450	so on.
		1451
		1452	=head1 ENVIRONMENT VARIABLES
		1453
		1454	The following environment variables are used by this module or its
		1455	submodules.
		1456
		1457	Note that AnyEvent will remove I<all> environment variables starting with
		1458	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1459	enabled.
		1460
		1461	=over 4
		1462
		1463	=item C<PERL_ANYEVENT_VERBOSE>
		1464
		1465	By default, AnyEvent will be completely silent except in fatal
		1466	conditions. You can set this environment variable to make AnyEvent more
		1467	talkative.
		1468
		1469	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1470	conditions, such as not being able to load the event model specified by
		1471	C<PERL_ANYEVENT_MODEL>.
		1472
		1473	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1474	model it chooses.
		1475
		1476	=item C<PERL_ANYEVENT_STRICT>
		1477
		1478	AnyEvent does not do much argument checking by default, as thorough
		1479	argument checking is very costly. Setting this variable to a true value
		1480	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1481	check the arguments passed to most method calls. If it finds any problems,
		1482	it will croak.
		1483
		1484	In other words, enables "strict" mode.
		1485
		1486	Unlike C<use strict>, it is definitely recommended to keep it off in
		1487	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1488	developing programs can be very useful, however.
		1489
		1490	=item C<PERL_ANYEVENT_MODEL>
		1491
		1492	This can be used to specify the event model to be used by AnyEvent, before
		1493	auto detection and -probing kicks in. It must be a string consisting
		1494	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1495	and the resulting module name is loaded and if the load was successful,
		1496	used as event model. If it fails to load AnyEvent will proceed with
		1497	auto detection and -probing.
		1498
		1499	This functionality might change in future versions.
		1500
		1501	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1502	could start your program like this:
		1503
		1504	PERL_ANYEVENT_MODEL=Perl perl ...
		1505
		1506	=item C<PERL_ANYEVENT_PROTOCOLS>
		1507
		1508	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1509	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1510	of auto probing).
		1511
		1512	Must be set to a comma-separated list of protocols or address families,
		1513	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1514	used, and preference will be given to protocols mentioned earlier in the
		1515	list.
		1516
		1517	This variable can effectively be used for denial-of-service attacks
		1518	against local programs (e.g. when setuid), although the impact is likely
		1519	small, as the program has to handle conenction and other failures anyways.
		1520
		1521	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1522	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1523	- only support IPv4, never try to resolve or contact IPv6
		1524	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1525	IPv6, but prefer IPv6 over IPv4.
		1526
		1527	=item C<PERL_ANYEVENT_EDNS0>
		1528
		1529	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1530	for DNS. This extension is generally useful to reduce DNS traffic, but
		1531	some (broken) firewalls drop such DNS packets, which is why it is off by
		1532	default.
		1533
		1534	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1535	EDNS0 in its DNS requests.
		1536
		1537	=item C<PERL_ANYEVENT_MAX_FORKS>
		1538
		1539	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1540	will create in parallel.
		1541
		1542	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1543
		1544	The default value for the C<max_outstanding> parameter for the default DNS
		1545	resolver - this is the maximum number of parallel DNS requests that are
		1546	sent to the DNS server.
		1547
		1548	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1549
		1550	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1551	configuration) in the default resolver. When set to the empty string, no
		1552	default config will be used.
		1553
		1554	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1555
		1556	When neither C<ca_file> nor C<ca_path> was specified during
		1557	L<AnyEvent::TLS> context creation, and either of these environment
		1558	variables exist, they will be used to specify CA certificate locations
		1559	instead of a system-dependent default.
		1560
		1561	=back
1144		1562
1145	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1563	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1146		1564
1147	This is an advanced topic that you do not normally need to use AnyEvent in	1565	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	1566	a module. This section is only of use to event loop authors who want to
…		…
1182		1600
1183	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1601	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1184	condition variables: code blocking while waiting for a condition will	1602	condition variables: code blocking while waiting for a condition will
1185	C<die>. This still works with most modules/usages, and blocking calls must	1603	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.	1604	not be done in an interactive application, so it makes sense.
1187
1188	=head1 ENVIRONMENT VARIABLES
1189
1190	The following environment variables are used by this module:
1191
1192	=over 4
1193
1194	=item C<PERL_ANYEVENT_VERBOSE>
1195
1196	By default, AnyEvent will be completely silent except in fatal
1197	conditions. You can set this environment variable to make AnyEvent more
1198	talkative.
1199
1200	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1201	conditions, such as not being able to load the event model specified by
1202	C<PERL_ANYEVENT_MODEL>.
1203
1204	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1205	model it chooses.
1206
1207	=item C<PERL_ANYEVENT_STRICT>
1208
1209	AnyEvent does not do much argument checking by default, as thorough
1210	argument checking is very costly. Setting this variable to a true value
1211	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1212	check the arguments passed to most method calls. If it finds any problems
1213	it will croak.
1214
1215	In other words, enables "strict" mode.
1216
1217	Unlike C<use strict> it is definitely recommended ot keep it off in
1218	production.
1219
1220	=item C<PERL_ANYEVENT_MODEL>
1221
1222	This can be used to specify the event model to be used by AnyEvent, before
1223	auto detection and -probing kicks in. It must be a string consisting
1224	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1225	and the resulting module name is loaded and if the load was successful,
1226	used as event model. If it fails to load AnyEvent will proceed with
1227	auto detection and -probing.
1228
1229	This functionality might change in future versions.
1230
1231	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1232	could start your program like this:
1233
1234	PERL_ANYEVENT_MODEL=Perl perl ...
1235
1236	=item C<PERL_ANYEVENT_PROTOCOLS>
1237
1238	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1239	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1240	of auto probing).
1241
1242	Must be set to a comma-separated list of protocols or address families,
1243	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1244	used, and preference will be given to protocols mentioned earlier in the
1245	list.
1246
1247	This variable can effectively be used for denial-of-service attacks
1248	against local programs (e.g. when setuid), although the impact is likely
1249	small, as the program has to handle connection errors already-
1250
1251	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1252	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1253	- only support IPv4, never try to resolve or contact IPv6
1254	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1255	IPv6, but prefer IPv6 over IPv4.
1256
1257	=item C<PERL_ANYEVENT_EDNS0>
1258
1259	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1260	for DNS. This extension is generally useful to reduce DNS traffic, but
1261	some (broken) firewalls drop such DNS packets, which is why it is off by
1262	default.
1263
1264	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1265	EDNS0 in its DNS requests.
1266
1267	=item C<PERL_ANYEVENT_MAX_FORKS>
1268
1269	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1270	will create in parallel.
1271
1272	=back
1273		1605
1274	=head1 EXAMPLE PROGRAM	1606	=head1 EXAMPLE PROGRAM
1275		1607
1276	The following program uses an I/O watcher to read data from STDIN, a timer	1608	The following program uses an I/O watcher to read data from STDIN, a timer
1277	to display a message once per second, and a condition variable to quit the	1609	to display a message once per second, and a condition variable to quit the
…		…
1471	watcher.	1803	watcher.
1472		1804
1473	=head3 Results	1805	=head3 Results
1474		1806
1475	name watchers bytes create invoke destroy comment	1807	name watchers bytes create invoke destroy comment
1476	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1808	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1477	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1809	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1478	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1810	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1479	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1811	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1480	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1812	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1481	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1813	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1814	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1815	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1482	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1816	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1483	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1817	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1484	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1818	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1485	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1819	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1486		1820
1487	=head3 Discussion	1821	=head3 Discussion
1488		1822
1489	The benchmark does I<not> measure scalability of the event loop very	1823	The benchmark does I<not> measure scalability of the event loop very
1490	well. For example, a select-based event loop (such as the pure perl one)	1824	well. For example, a select-based event loop (such as the pure perl one)
…		…
1515	performance becomes really bad with lots of file descriptors (and few of	1849	performance becomes really bad with lots of file descriptors (and few of
1516	them active), of course, but this was not subject of this benchmark.	1850	them active), of course, but this was not subject of this benchmark.
1517		1851
1518	The C<Event> module has a relatively high setup and callback invocation	1852	The C<Event> module has a relatively high setup and callback invocation
1519	cost, but overall scores in on the third place.	1853	cost, but overall scores in on the third place.
		1854
		1855	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1856	when using its pure perl backend.
1520		1857
1521	C<Glib>'s memory usage is quite a bit higher, but it features a	1858	C<Glib>'s memory usage is quite a bit higher, but it features a
1522	faster callback invocation and overall ends up in the same class as	1859	faster callback invocation and overall ends up in the same class as
1523	C<Event>. However, Glib scales extremely badly, doubling the number of	1860	C<Event>. However, Glib scales extremely badly, doubling the number of
1524	watchers increases the processing time by more than a factor of four,	1861	watchers increases the processing time by more than a factor of four,
…		…
1602	it to another server. This includes deleting the old timeout and creating	1939	it to another server. This includes deleting the old timeout and creating
1603	a new one that moves the timeout into the future.	1940	a new one that moves the timeout into the future.
1604		1941
1605	=head3 Results	1942	=head3 Results
1606		1943
1607	name sockets create request	1944	name sockets create request
1608	EV 20000 69.01 11.16	1945	EV 20000 69.01 11.16
1609	Perl 20000 73.32 35.87	1946	Perl 20000 73.32 35.87
		1947	IOAsync 20000 157.00 98.14 epoll
		1948	IOAsync 20000 159.31 616.06 poll
1610	Event 20000 212.62 257.32	1949	Event 20000 212.62 257.32
1611	Glib 20000 651.16 1896.30	1950	Glib 20000 651.16 1896.30
1612	POE 20000 349.67 12317.24 uses POE::Loop::Event	1951	POE 20000 349.67 12317.24 uses POE::Loop::Event
1613		1952
1614	=head3 Discussion	1953	=head3 Discussion
1615		1954
1616	This benchmark I<does> measure scalability and overall performance of the	1955	This benchmark I<does> measure scalability and overall performance of the
1617	particular event loop.	1956	particular event loop.
…		…
1619	EV is again fastest. Since it is using epoll on my system, the setup time	1958	EV is again fastest. Since it is using epoll on my system, the setup time
1620	is relatively high, though.	1959	is relatively high, though.
1621		1960
1622	Perl surprisingly comes second. It is much faster than the C-based event	1961	Perl surprisingly comes second. It is much faster than the C-based event
1623	loops Event and Glib.	1962	loops Event and Glib.
		1963
		1964	IO::Async performs very well when using its epoll backend, and still quite
		1965	good compared to Glib when using its pure perl backend.
1624		1966
1625	Event suffers from high setup time as well (look at its code and you will	1967	Event suffers from high setup time as well (look at its code and you will
1626	understand why). Callback invocation also has a high overhead compared to	1968	understand why). Callback invocation also has a high overhead compared to
1627	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1969	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1628	uses select or poll in basically all documented configurations.	1970	uses select or poll in basically all documented configurations.
…		…
1691	=item * C-based event loops perform very well with small number of	2033	=item * C-based event loops perform very well with small number of
1692	watchers, as the management overhead dominates.	2034	watchers, as the management overhead dominates.
1693		2035
1694	=back	2036	=back
1695		2037
		2038	=head2 THE IO::Lambda BENCHMARK
		2039
		2040	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2041	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2042	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2043	shouldn't come as a surprise to anybody). As such, the benchmark is
		2044	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2045	very optimal. But how would AnyEvent compare when used without the extra
		2046	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2047
		2048	The benchmark itself creates an echo-server, and then, for 500 times,
		2049	connects to the echo server, sends a line, waits for the reply, and then
		2050	creates the next connection. This is a rather bad benchmark, as it doesn't
		2051	test the efficiency of the framework or much non-blocking I/O, but it is a
		2052	benchmark nevertheless.
		2053
		2054	name runtime
		2055	Lambda/select 0.330 sec
		2056	+ optimized 0.122 sec
		2057	Lambda/AnyEvent 0.327 sec
		2058	+ optimized 0.138 sec
		2059	Raw sockets/select 0.077 sec
		2060	POE/select, components 0.662 sec
		2061	POE/select, raw sockets 0.226 sec
		2062	POE/select, optimized 0.404 sec
		2063
		2064	AnyEvent/select/nb 0.085 sec
		2065	AnyEvent/EV/nb 0.068 sec
		2066	+state machine 0.134 sec
		2067
		2068	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2069	benchmarks actually make blocking connects and use 100% blocking I/O,
		2070	defeating the purpose of an event-based solution. All of the newly
		2071	written AnyEvent benchmarks use 100% non-blocking connects (using
		2072	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2073	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2074	generally require a lot more bookkeeping and event handling than blocking
		2075	connects (which involve a single syscall only).
		2076
		2077	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2078	offers similar expressive power as POE and IO::Lambda, using conventional
		2079	Perl syntax. This means that both the echo server and the client are 100%
		2080	non-blocking, further placing it at a disadvantage.
		2081
		2082	As you can see, the AnyEvent + EV combination even beats the
		2083	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2084	backend easily beats IO::Lambda and POE.
		2085
		2086	And even the 100% non-blocking version written using the high-level (and
		2087	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2088	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2089	in a non-blocking way.
		2090
		2091	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2092	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2093	part of the IO::lambda distribution and were used without any changes.
		2094
		2095
		2096	=head1 SIGNALS
		2097
		2098	AnyEvent currently installs handlers for these signals:
		2099
		2100	=over 4
		2101
		2102	=item SIGCHLD
		2103
		2104	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2105	emulation for event loops that do not support them natively. Also, some
		2106	event loops install a similar handler.
		2107
		2108	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2109	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2110
		2111	=item SIGPIPE
		2112
		2113	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2114	when AnyEvent gets loaded.
		2115
		2116	The rationale for this is that AnyEvent users usually do not really depend
		2117	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2118	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2119	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2120	some random socket.
		2121
		2122	The rationale for installing a no-op handler as opposed to ignoring it is
		2123	that this way, the handler will be restored to defaults on exec.
		2124
		2125	Feel free to install your own handler, or reset it to defaults.
		2126
		2127	=back
		2128
		2129	=cut
		2130
		2131	undef $SIG{CHLD}
		2132	if $SIG{CHLD} eq 'IGNORE';
		2133
		2134	$SIG{PIPE} = sub { }
		2135	unless defined $SIG{PIPE};
1696		2136
1697	=head1 FORK	2137	=head1 FORK
1698		2138
1699	Most event libraries are not fork-safe. The ones who are usually are	2139	Most event libraries are not fork-safe. The ones who are usually are
1700	because they rely on inefficient but fork-safe C<select> or C<poll>	2140	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1721	use AnyEvent;	2161	use AnyEvent;
1722		2162
1723	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2163	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1724	be used to probe what backend is used and gain other information (which is	2164	be used to probe what backend is used and gain other information (which is
1725	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2165	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1726	$ENV{PERL_ANYEGENT_STRICT}.	2166	$ENV{PERL_ANYEVENT_STRICT}.
		2167
		2168	Note that AnyEvent will remove I<all> environment variables starting with
		2169	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2170	enabled.
1727		2171
1728		2172
1729	=head1 BUGS	2173	=head1 BUGS
1730		2174
1731	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2175	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1732	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2176	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1733	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2177	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1734	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2178	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1735	pronounced).	2179	pronounced).
1736		2180
1737		2181
1738	=head1 SEE ALSO	2182	=head1 SEE ALSO
1739		2183
…		…
1743	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2187	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1744		2188
1745	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2189	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1746	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2190	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1747	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2191	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1748	L<AnyEvent::Impl::POE>.	2192	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1749		2193
1750	Non-blocking file handles, sockets, TCP clients and	2194	Non-blocking file handles, sockets, TCP clients and
1751	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2195	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1752		2196
1753	Asynchronous DNS: L<AnyEvent::DNS>.	2197	Asynchronous DNS: L<AnyEvent::DNS>.
1754		2198
1755	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2199	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2200	L<Coro::Event>,
1756		2201
1757	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2202	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2203	L<AnyEvent::HTTP>.
1758		2204
1759		2205
1760	=head1 AUTHOR	2206	=head1 AUTHOR
1761		2207
1762	Marc Lehmann <schmorp@schmorp.de>	2208	Marc Lehmann <schmorp@schmorp.de>

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