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Revision 1.253 by root, Tue Jul 21 06:00:47 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - events independent of event loop implementation
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 { ... });
12		14
		15	# one-shot or repeating timers
13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
15		18
16	print AnyEvent->now; # prints current event loop time	19	print AnyEvent->now; # prints current event loop time
17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
18		21
		22	# POSIX signal
19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });	23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
20		24
		25	# child process exit
21	my $w = AnyEvent->child (pid => $pid, cb => sub {	26	my $w = AnyEvent->child (pid => $pid, cb => sub {
22	my ($pid, $status) = @_;	27	my ($pid, $status) = @_;
23	...	28	...
24	});	29	});
		30
		31	# called when event loop idle (if applicable)
		32	my $w = AnyEvent->idle (cb => sub { ... });
25		33
26	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
27	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
28	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
29	# use a condvar in callback mode:	37	# use a condvar in callback mode:
…		…
32	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
33		41
34	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
35	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
36	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	Respository>, at L<http://anyevent.schmorp.de>, for more info.
37		53
38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
39		55
40	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
41	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
…		…
168	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
169		185
170	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
171	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
172		188
173	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch	189	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
174	for events (AnyEvent might or might not keep a reference to this file	190	for events (AnyEvent might or might not keep a reference to this file
175	handle). Note that only file handles pointing to things for which	191	handle). Note that only file handles pointing to things for which
176	non-blocking operation makes sense are allowed. This includes sockets,	192	non-blocking operation makes sense are allowed. This includes sockets,
177	most character devices, pipes, fifos and so on, but not for example files	193	most character devices, pipes, fifos and so on, but not for example files
178	or block devices.	194	or block devices.
…		…
353	invocation, and callback invocation will be synchronous. Synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
354	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,
355	but it is guaranteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
356		372
357	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
358	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
359		376
360	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
361	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
362		380
363	Example: exit on SIGINT	381	Example: exit on SIGINT
364		382
365	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$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.
366		400
367	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
368		402
369	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.
370		404
…		…
384		418
385	There is a slight catch to child watchers, however: you usually start them	419	There is a slight catch to child watchers, however: you usually start them
386	I<after> the child process was created, and this means the process could	420	I<after> the child process was created, and this means the process could
387	have exited already (and no SIGCHLD will be sent anymore).	421	have exited already (and no SIGCHLD will be sent anymore).
388		422
389	Not all event models handle this correctly (POE doesn't), but even for	423	Not all event models handle this correctly (neither POE nor IO::Async do,
		424	see their AnyEvent::Impl manpages for details), but even for event models
390	event models that I<do> handle this correctly, they usually need to be	425	that I<do> handle this correctly, they usually need to be loaded before
391	loaded before the process exits (i.e. before you fork in the first place).	426	the process exits (i.e. before you fork in the first place). AnyEvent's
		427	pure perl event loop handles all cases correctly regardless of when you
		428	start the watcher.
392		429
393	This means you cannot create a child watcher as the very first thing in an	430	This means you cannot create a child watcher as the very first
394	AnyEvent program, you I<have> to create at least one watcher before you	431	thing in an AnyEvent program, you I<have> to create at least one
395	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	432	watcher before you C<fork> the child (alternatively, you can call
		433	C<AnyEvent::detect>).
		434
		435	As most event loops do not support waiting for child events, they will be
		436	emulated by AnyEvent in most cases, in which the latency and race problems
		437	mentioned in the description of signal watchers apply.
396		438
397	Example: fork a process and wait for it	439	Example: fork a process and wait for it
398		440
399	my $done = AnyEvent->condvar;	441	my $done = AnyEvent->condvar;
400		442
…		…
410	);	452	);
411		453
412	# do something else, then wait for process exit	454	# do something else, then wait for process exit
413	$done->recv;	455	$done->recv;
414		456
		457	=head2 IDLE WATCHERS
		458
		459	Sometimes there is a need to do something, but it is not so important
		460	to do it instantly, but only when there is nothing better to do. This
		461	"nothing better to do" is usually defined to be "no other events need
		462	attention by the event loop".
		463
		464	Idle watchers ideally get invoked when the event loop has nothing
		465	better to do, just before it would block the process to wait for new
		466	events. Instead of blocking, the idle watcher is invoked.
		467
		468	Most event loops unfortunately do not really support idle watchers (only
		469	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		470	will simply call the callback "from time to time".
		471
		472	Example: read lines from STDIN, but only process them when the
		473	program is otherwise idle:
		474
		475	my @lines; # read data
		476	my $idle_w;
		477	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		478	push @lines, scalar <STDIN>;
		479
		480	# start an idle watcher, if not already done
		481	$idle_w ||= AnyEvent->idle (cb => sub {
		482	# handle only one line, when there are lines left
		483	if (my $line = shift @lines) {
		484	print "handled when idle: $line";
		485	} else {
		486	# otherwise disable the idle watcher again
		487	undef $idle_w;
		488	}
		489	});
		490	});
		491
415	=head2 CONDITION VARIABLES	492	=head2 CONDITION VARIABLES
416		493
417	If you are familiar with some event loops you will know that all of them	494	If you are familiar with some event loops you will know that all of them
418	require you to run some blocking "loop", "run" or similar function that	495	require you to run some blocking "loop", "run" or similar function that
419	will actively watch for new events and call your callbacks.	496	will actively watch for new events and call your callbacks.
420		497
421	AnyEvent is different, it expects somebody else to run the event loop and	498	AnyEvent is slightly different: it expects somebody else to run the event
422	will only block when necessary (usually when told by the user).	499	loop and will only block when necessary (usually when told by the user).
423		500
424	The instrument to do that is called a "condition variable", so called	501	The instrument to do that is called a "condition variable", so called
425	because they represent a condition that must become true.	502	because they represent a condition that must become true.
426		503
		504	Now is probably a good time to look at the examples further below.
		505
427	Condition variables can be created by calling the C<< AnyEvent->condvar	506	Condition variables can be created by calling the C<< AnyEvent->condvar
428	>> method, usually without arguments. The only argument pair allowed is	507	>> method, usually without arguments. The only argument pair allowed is
429
430	C<cb>, which specifies a callback to be called when the condition variable	508	C<cb>, which specifies a callback to be called when the condition variable
431	becomes true, with the condition variable as the first argument (but not	509	becomes true, with the condition variable as the first argument (but not
432	the results).	510	the results).
433		511
434	After creation, the condition variable is "false" until it becomes "true"	512	After creation, the condition variable is "false" until it becomes "true"
…		…
439	Condition variables are similar to callbacks, except that you can	517	Condition variables are similar to callbacks, except that you can
440	optionally wait for them. They can also be called merge points - points	518	optionally wait for them. They can also be called merge points - points
441	in time where multiple outstanding events have been processed. And yet	519	in time where multiple outstanding events have been processed. And yet
442	another way to call them is transactions - each condition variable can be	520	another way to call them is transactions - each condition variable can be
443	used to represent a transaction, which finishes at some point and delivers	521	used to represent a transaction, which finishes at some point and delivers
444	a result.	522	a result. And yet some people know them as "futures" - a promise to
		523	compute/deliver something that you can wait for.
445		524
446	Condition variables are very useful to signal that something has finished,	525	Condition variables are very useful to signal that something has finished,
447	for example, if you write a module that does asynchronous http requests,	526	for example, if you write a module that does asynchronous http requests,
448	then a condition variable would be the ideal candidate to signal the	527	then a condition variable would be the ideal candidate to signal the
449	availability of results. The user can either act when the callback is	528	availability of results. The user can either act when the callback is
…		…
483	after => 1,	562	after => 1,
484	cb => sub { $result_ready->send },	563	cb => sub { $result_ready->send },
485	);	564	);
486		565
487	# this "blocks" (while handling events) till the callback	566	# this "blocks" (while handling events) till the callback
488	# calls send	567	# calls -<send
489	$result_ready->recv;	568	$result_ready->recv;
490		569
491	Example: wait for a timer, but take advantage of the fact that	570	Example: wait for a timer, but take advantage of the fact that condition
492	condition variables are also code references.	571	variables are also callable directly.
493		572
494	my $done = AnyEvent->condvar;	573	my $done = AnyEvent->condvar;
495	my $delay = AnyEvent->timer (after => 5, cb => $done);	574	my $delay = AnyEvent->timer (after => 5, cb => $done);
496	$done->recv;	575	$done->recv;
497		576
…		…
503		582
504	...	583	...
505		584
506	my @info = $couchdb->info->recv;	585	my @info = $couchdb->info->recv;
507		586
508	And this is how you would just ste a callback to be called whenever the	587	And this is how you would just set a callback to be called whenever the
509	results are available:	588	results are available:
510		589
511	$couchdb->info->cb (sub {	590	$couchdb->info->cb (sub {
512	my @info = $_[0]->recv;	591	my @info = $_[0]->recv;
513	});	592	});
…		…
531	immediately from within send.	610	immediately from within send.
532		611
533	Any arguments passed to the C<send> call will be returned by all	612	Any arguments passed to the C<send> call will be returned by all
534	future C<< ->recv >> calls.	613	future C<< ->recv >> calls.
535		614
536	Condition variables are overloaded so one can call them directly	615	Condition variables are overloaded so one can call them directly (as if
537	(as a code reference). Calling them directly is the same as calling	616	they were a code reference). Calling them directly is the same as calling
538	C<send>. Note, however, that many C-based event loops do not handle	617	C<send>.
539	overloading, so as tempting as it may be, passing a condition variable
540	instead of a callback does not work. Both the pure perl and EV loops
541	support overloading, however, as well as all functions that use perl to
542	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
543	example).
544		618
545	=item $cv->croak ($error)	619	=item $cv->croak ($error)
546		620
547	Similar to send, but causes all call's to C<< ->recv >> to invoke	621	Similar to send, but causes all call's to C<< ->recv >> to invoke
548	C<Carp::croak> with the given error message/object/scalar.	622	C<Carp::croak> with the given error message/object/scalar.
549		623
550	This can be used to signal any errors to the condition variable	624	This can be used to signal any errors to the condition variable
551	user/consumer.	625	user/consumer. Doing it this way instead of calling C<croak> directly
		626	delays the error detetcion, but has the overwhelmign advantage that it
		627	diagnoses the error at the place where the result is expected, and not
		628	deep in some event clalback without connection to the actual code causing
		629	the problem.
552		630
553	=item $cv->begin ([group callback])	631	=item $cv->begin ([group callback])
554		632
555	=item $cv->end	633	=item $cv->end
556
557	These two methods are EXPERIMENTAL and MIGHT CHANGE.
558		634
559	These two methods can be used to combine many transactions/events into	635	These two methods can be used to combine many transactions/events into
560	one. For example, a function that pings many hosts in parallel might want	636	one. For example, a function that pings many hosts in parallel might want
561	to use a condition variable for the whole process.	637	to use a condition variable for the whole process.
562		638
…		…
564	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	640	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
565	>>, the (last) callback passed to C<begin> will be executed. That callback	641	>>, the (last) callback passed to C<begin> will be executed. That callback
566	is I<supposed> to call C<< ->send >>, but that is not required. If no	642	is I<supposed> to call C<< ->send >>, but that is not required. If no
567	callback was set, C<send> will be called without any arguments.	643	callback was set, C<send> will be called without any arguments.
568		644
569	Let's clarify this with the ping example:	645	You can think of C<< $cv->send >> giving you an OR condition (one call
		646	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		647	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		648
		649	Let's start with a simple example: you have two I/O watchers (for example,
		650	STDOUT and STDERR for a program), and you want to wait for both streams to
		651	close before activating a condvar:
		652
		653	my $cv = AnyEvent->condvar;
		654
		655	$cv->begin; # first watcher
		656	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		657	defined sysread $fh1, my $buf, 4096
		658	or $cv->end;
		659	});
		660
		661	$cv->begin; # second watcher
		662	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		663	defined sysread $fh2, my $buf, 4096
		664	or $cv->end;
		665	});
		666
		667	$cv->recv;
		668
		669	This works because for every event source (EOF on file handle), there is
		670	one call to C<begin>, so the condvar waits for all calls to C<end> before
		671	sending.
		672
		673	The ping example mentioned above is slightly more complicated, as the
		674	there are results to be passwd back, and the number of tasks that are
		675	begung can potentially be zero:
570		676
571	my $cv = AnyEvent->condvar;	677	my $cv = AnyEvent->condvar;
572		678
573	my %result;	679	my %result;
574	$cv->begin (sub { $cv->send (\%result) });	680	$cv->begin (sub { $cv->send (\%result) });
…		…
594	loop, which serves two important purposes: first, it sets the callback	700	loop, which serves two important purposes: first, it sets the callback
595	to be called once the counter reaches C<0>, and second, it ensures that	701	to be called once the counter reaches C<0>, and second, it ensures that
596	C<send> is called even when C<no> hosts are being pinged (the loop	702	C<send> is called even when C<no> hosts are being pinged (the loop
597	doesn't execute once).	703	doesn't execute once).
598		704
599	This is the general pattern when you "fan out" into multiple subrequests:	705	This is the general pattern when you "fan out" into multiple (but
600	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	706	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
601	is called at least once, and then, for each subrequest you start, call	707	the callback and ensure C<end> is called at least once, and then, for each
602	C<begin> and for each subrequest you finish, call C<end>.	708	subrequest you start, call C<begin> and for each subrequest you finish,
		709	call C<end>.
603		710
604	=back	711	=back
605		712
606	=head3 METHODS FOR CONSUMERS	713	=head3 METHODS FOR CONSUMERS
607		714
…		…
623	function will call C<croak>.	730	function will call C<croak>.
624		731
625	In list context, all parameters passed to C<send> will be returned,	732	In list context, all parameters passed to C<send> will be returned,
626	in scalar context only the first one will be returned.	733	in scalar context only the first one will be returned.
627		734
		735	Note that doing a blocking wait in a callback is not supported by any
		736	event loop, that is, recursive invocation of a blocking C<< ->recv
		737	>> is not allowed, and the C<recv> call will C<croak> if such a
		738	condition is detected. This condition can be slightly loosened by using
		739	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		740	any thread that doesn't run the event loop itself.
		741
628	Not all event models support a blocking wait - some die in that case	742	Not all event models support a blocking wait - some die in that case
629	(programs might want to do that to stay interactive), so I<if you are	743	(programs might want to do that to stay interactive), so I<if you are
630	using this from a module, never require a blocking wait>, but let the	744	using this from a module, never require a blocking wait>. Instead, let the
631	caller decide whether the call will block or not (for example, by coupling	745	caller decide whether the call will block or not (for example, by coupling
632	condition variables with some kind of request results and supporting	746	condition variables with some kind of request results and supporting
633	callbacks so the caller knows that getting the result will not block,	747	callbacks so the caller knows that getting the result will not block,
634	while still supporting blocking waits if the caller so desires).	748	while still supporting blocking waits if the caller so desires).
635		749
636	Another reason I<never> to C<< ->recv >> in a module is that you cannot
637	sensibly have two C<< ->recv >>'s in parallel, as that would require
638	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
639	can supply.
640
641	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
642	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
643	versions and also integrates coroutines into AnyEvent, making blocking
644	C<< ->recv >> calls perfectly safe as long as they are done from another
645	coroutine (one that doesn't run the event loop).
646
647	You can ensure that C<< -recv >> never blocks by setting a callback and	750	You can ensure that C<< -recv >> never blocks by setting a callback and
648	only calling C<< ->recv >> from within that callback (or at a later	751	only calling C<< ->recv >> from within that callback (or at a later
649	time). This will work even when the event loop does not support blocking	752	time). This will work even when the event loop does not support blocking
650	waits otherwise.	753	waits otherwise.
651		754
…		…
664	variable itself. Calling C<recv> inside the callback or at any later time	767	variable itself. Calling C<recv> inside the callback or at any later time
665	is guaranteed not to block.	768	is guaranteed not to block.
666		769
667	=back	770	=back
668		771
		772	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		773
		774	The available backend classes are (every class has its own manpage):
		775
		776	=over 4
		777
		778	=item Backends that are autoprobed when no other event loop can be found.
		779
		780	EV is the preferred backend when no other event loop seems to be in
		781	use. If EV is not installed, then AnyEvent will try Event, and, failing
		782	that, will fall back to its own pure-perl implementation, which is
		783	available everywhere as it comes with AnyEvent itself.
		784
		785	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		786	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		787	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		788
		789	=item Backends that are transparently being picked up when they are used.
		790
		791	These will be used when they are currently loaded when the first watcher
		792	is created, in which case it is assumed that the application is using
		793	them. This means that AnyEvent will automatically pick the right backend
		794	when the main program loads an event module before anything starts to
		795	create watchers. Nothing special needs to be done by the main program.
		796
		797	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		798	AnyEvent::Impl::Tk based on Tk, very broken.
		799	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		800	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		801
		802	=item Backends with special needs.
		803
		804	Qt requires the Qt::Application to be instantiated first, but will
		805	otherwise be picked up automatically. As long as the main program
		806	instantiates the application before any AnyEvent watchers are created,
		807	everything should just work.
		808
		809	AnyEvent::Impl::Qt based on Qt.
		810
		811	Support for IO::Async can only be partial, as it is too broken and
		812	architecturally limited to even support the AnyEvent API. It also
		813	is the only event loop that needs the loop to be set explicitly, so
		814	it can only be used by a main program knowing about AnyEvent. See
		815	L<AnyEvent::Impl::Async> for the gory details.
		816
		817	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		818
		819	=item Event loops that are indirectly supported via other backends.
		820
		821	Some event loops can be supported via other modules:
		822
		823	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		824
		825	B<WxWidgets> has no support for watching file handles. However, you can
		826	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		827	polls 20 times per second, which was considered to be too horrible to even
		828	consider for AnyEvent.
		829
		830	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		831	backend, so it can be supported through POE.
		832
		833	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		834	load L<POE> when detecting them, in the hope that POE will pick them up,
		835	in which case everything will be automatic.
		836
		837	=back
		838
669	=head1 GLOBAL VARIABLES AND FUNCTIONS	839	=head1 GLOBAL VARIABLES AND FUNCTIONS
670		840
		841	These are not normally required to use AnyEvent, but can be useful to
		842	write AnyEvent extension modules.
		843
671	=over 4	844	=over 4
672		845
673	=item $AnyEvent::MODEL	846	=item $AnyEvent::MODEL
674		847
675	Contains C<undef> until the first watcher is being created. Then it	848	Contains C<undef> until the first watcher is being created, before the
		849	backend has been autodetected.
		850
676	contains the event model that is being used, which is the name of the	851	Afterwards it contains the event model that is being used, which is the
677	Perl class implementing the model. This class is usually one of the	852	name of the Perl class implementing the model. This class is usually one
678	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	853	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
679	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	854	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
680		855	will be C<urxvt::anyevent>).
681	The known classes so far are:
682
683	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
684	AnyEvent::Impl::Event based on Event, second best choice.
685	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
686	AnyEvent::Impl::Glib based on Glib, third-best choice.
687	AnyEvent::Impl::Tk based on Tk, very bad choice.
688	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
689	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
690	AnyEvent::Impl::POE based on POE, not generic enough for full support.
691
692	There is no support for WxWidgets, as WxWidgets has no support for
693	watching file handles. However, you can use WxWidgets through the
694	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
695	second, which was considered to be too horrible to even consider for
696	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
697	it's adaptor.
698
699	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
700	autodetecting them.
701		856
702	=item AnyEvent::detect	857	=item AnyEvent::detect
703		858
704	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	859	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
705	if necessary. You should only call this function right before you would	860	if necessary. You should only call this function right before you would
706	have created an AnyEvent watcher anyway, that is, as late as possible at	861	have created an AnyEvent watcher anyway, that is, as late as possible at
707	runtime.	862	runtime, and not e.g. while initialising of your module.
		863
		864	If you need to do some initialisation before AnyEvent watchers are
		865	created, use C<post_detect>.
708		866
709	=item $guard = AnyEvent::post_detect { BLOCK }	867	=item $guard = AnyEvent::post_detect { BLOCK }
710		868
711	Arranges for the code block to be executed as soon as the event model is	869	Arranges for the code block to be executed as soon as the event model is
712	autodetected (or immediately if this has already happened).	870	autodetected (or immediately if this has already happened).
713		871
		872	The block will be executed I<after> the actual backend has been detected
		873	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		874	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		875	other initialisations - see the sources of L<AnyEvent::Strict> or
		876	L<AnyEvent::AIO> to see how this is used.
		877
		878	The most common usage is to create some global watchers, without forcing
		879	event module detection too early, for example, L<AnyEvent::AIO> creates
		880	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		881	avoid autodetecting the event module at load time.
		882
714	If called in scalar or list context, then it creates and returns an object	883	If called in scalar or list context, then it creates and returns an object
715	that automatically removes the callback again when it is destroyed. See	884	that automatically removes the callback again when it is destroyed (or
		885	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
716	L<Coro::BDB> for a case where this is useful.	886	a case where this is useful.
		887
		888	Example: Create a watcher for the IO::AIO module and store it in
		889	C<$WATCHER>. Only do so after the event loop is initialised, though.
		890
		891	our WATCHER;
		892
		893	my $guard = AnyEvent::post_detect {
		894	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		895	};
		896
		897	# the ||= is important in case post_detect immediately runs the block,
		898	# as to not clobber the newly-created watcher. assigning both watcher and
		899	# post_detect guard to the same variable has the advantage of users being
		900	# able to just C<undef $WATCHER> if the watcher causes them grief.
		901
		902	$WATCHER ||= $guard;
717		903
718	=item @AnyEvent::post_detect	904	=item @AnyEvent::post_detect
719		905
720	If there are any code references in this array (you can C<push> to it	906	If there are any code references in this array (you can C<push> to it
721	before or after loading AnyEvent), then they will called directly after	907	before or after loading AnyEvent), then they will called directly after
722	the event loop has been chosen.	908	the event loop has been chosen.
723		909
724	You should check C<$AnyEvent::MODEL> before adding to this array, though:	910	You should check C<$AnyEvent::MODEL> before adding to this array, though:
725	if it contains a true value then the event loop has already been detected,	911	if it is defined then the event loop has already been detected, and the
726	and the array will be ignored.	912	array will be ignored.
727		913
728	Best use C<AnyEvent::post_detect { BLOCK }> instead.	914	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		915	it,as it takes care of these details.
		916
		917	This variable is mainly useful for modules that can do something useful
		918	when AnyEvent is used and thus want to know when it is initialised, but do
		919	not need to even load it by default. This array provides the means to hook
		920	into AnyEvent passively, without loading it.
729		921
730	=back	922	=back
731		923
732	=head1 WHAT TO DO IN A MODULE	924	=head1 WHAT TO DO IN A MODULE
733		925
…		…
788		980
789		981
790	=head1 OTHER MODULES	982	=head1 OTHER MODULES
791		983
792	The following is a non-exhaustive list of additional modules that use	984	The following is a non-exhaustive list of additional modules that use
793	AnyEvent and can therefore be mixed easily with other AnyEvent modules	985	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
794	in the same program. Some of the modules come with AnyEvent, some are	986	modules and other event loops in the same program. Some of the modules
795	available via CPAN.	987	come with AnyEvent, most are available via CPAN.
796		988
797	=over 4	989	=over 4
798		990
799	=item L<AnyEvent::Util>	991	=item L<AnyEvent::Util>
800		992
…		…
809		1001
810	=item L<AnyEvent::Handle>	1002	=item L<AnyEvent::Handle>
811		1003
812	Provide read and write buffers, manages watchers for reads and writes,	1004	Provide read and write buffers, manages watchers for reads and writes,
813	supports raw and formatted I/O, I/O queued and fully transparent and	1005	supports raw and formatted I/O, I/O queued and fully transparent and
814	non-blocking SSL/TLS.	1006	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
815		1007
816	=item L<AnyEvent::DNS>	1008	=item L<AnyEvent::DNS>
817		1009
818	Provides rich asynchronous DNS resolver capabilities.	1010	Provides rich asynchronous DNS resolver capabilities.
819		1011
…		…
847		1039
848	=item L<AnyEvent::GPSD>	1040	=item L<AnyEvent::GPSD>
849		1041
850	A non-blocking interface to gpsd, a daemon delivering GPS information.	1042	A non-blocking interface to gpsd, a daemon delivering GPS information.
851		1043
		1044	=item L<AnyEvent::IRC>
		1045
		1046	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1047
		1048	=item L<AnyEvent::XMPP>
		1049
		1050	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1051	Net::XMPP2>.
		1052
852	=item L<AnyEvent::IGS>	1053	=item L<AnyEvent::IGS>
853		1054
854	A non-blocking interface to the Internet Go Server protocol (used by	1055	A non-blocking interface to the Internet Go Server protocol (used by
855	L<App::IGS>).	1056	L<App::IGS>).
856		1057
857	=item L<AnyEvent::IRC>
858
859	AnyEvent based IRC client module family (replacing the older Net::IRC3).
860
861	=item L<Net::XMPP2>
862
863	AnyEvent based XMPP (Jabber protocol) module family.
864
865	=item L<Net::FCP>	1058	=item L<Net::FCP>
866		1059
867	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1060	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
868	of AnyEvent.	1061	of AnyEvent.
869		1062
…		…
873		1066
874	=item L<Coro>	1067	=item L<Coro>
875		1068
876	Has special support for AnyEvent via L<Coro::AnyEvent>.	1069	Has special support for AnyEvent via L<Coro::AnyEvent>.
877		1070
878	=item L<IO::Lambda>
879
880	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
881
882	=back	1071	=back
883		1072
884	=cut	1073	=cut
885		1074
886	package AnyEvent;	1075	package AnyEvent;
887		1076
		1077	# basically a tuned-down version of common::sense
		1078	sub common_sense {
888	no warnings;	1079	# no warnings
		1080	${^WARNING_BITS} ^= ${^WARNING_BITS};
889	use strict qw(vars subs);	1081	# use strict vars subs
		1082	$^H |= 0x00000600;
		1083	}
890		1084
		1085	BEGIN { AnyEvent::common_sense }
		1086
891	use Carp;	1087	use Carp ();
892		1088
893	our $VERSION = 4.351;	1089	our $VERSION = 4.86;
894	our $MODEL;	1090	our $MODEL;
895		1091
896	our $AUTOLOAD;	1092	our $AUTOLOAD;
897	our @ISA;	1093	our @ISA;
898		1094
899	our @REGISTRY;	1095	our @REGISTRY;
900		1096
901	our $WIN32;	1097	our $WIN32;
902		1098
		1099	our $VERBOSE;
		1100
903	BEGIN {	1101	BEGIN {
904	my $win32 = ! ! ($^O =~ /mswin32/i);	1102	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
905	eval "sub WIN32(){ $win32 }";	1103	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
906	}
907		1104
		1105	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1106	if ${^TAINT};
		1107
908	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1108	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1109
		1110	}
		1111
		1112	our $MAX_SIGNAL_LATENCY = 10;
909		1113
910	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1114	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
911		1115
912	{	1116	{
913	my $idx;	1117	my $idx;
…		…
921	[Event:: => AnyEvent::Impl::Event::],	1125	[Event:: => AnyEvent::Impl::Event::],
922	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1126	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
923	# everything below here will not be autoprobed	1127	# everything below here will not be autoprobed
924	# as the pureperl backend should work everywhere	1128	# as the pureperl backend should work everywhere
925	# and is usually faster	1129	# and is usually faster
926	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
927	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1130	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
928	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1131	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1132	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
929	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1133	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
930	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1134	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
931	[Wx:: => AnyEvent::Impl::POE::],	1135	[Wx:: => AnyEvent::Impl::POE::],
932	[Prima:: => AnyEvent::Impl::POE::],	1136	[Prima:: => AnyEvent::Impl::POE::],
		1137	# IO::Async is just too broken - we would need workarounds for its
		1138	# byzantine signal and broken child handling, among others.
		1139	# IO::Async is rather hard to detect, as it doesn't have any
		1140	# obvious default class.
		1141	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1142	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1143	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
933	);	1144	);
934		1145
935	our %method = map +($_ => 1),	1146	our %method = map +($_ => 1),
936	qw(io timer time now now_update signal child condvar one_event DESTROY);	1147	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
937		1148
938	our @post_detect;	1149	our @post_detect;
939		1150
940	sub post_detect(&) {	1151	sub post_detect(&) {
941	my ($cb) = @_;	1152	my ($cb) = @_;
942		1153
943	if ($MODEL) {	1154	if ($MODEL) {
944	$cb->();	1155	$cb->();
945		1156
946	1	1157	undef
947	} else {	1158	} else {
948	push @post_detect, $cb;	1159	push @post_detect, $cb;
949		1160
950	defined wantarray	1161	defined wantarray
951	? bless \$cb, "AnyEvent::Util::PostDetect"	1162	? bless \$cb, "AnyEvent::Util::postdetect"
952	: ()	1163	: ()
953	}	1164	}
954	}	1165	}
955		1166
956	sub AnyEvent::Util::PostDetect::DESTROY {	1167	sub AnyEvent::Util::postdetect::DESTROY {
957	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1168	@post_detect = grep $_ != ${$_[0]}, @post_detect;
958	}	1169	}
959		1170
960	sub detect() {	1171	sub detect() {
961	unless ($MODEL) {	1172	unless ($MODEL) {
962	no strict 'refs';
963	local $SIG{__DIE__};	1173	local $SIG{__DIE__};
964		1174
965	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1175	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
966	my $model = "AnyEvent::Impl::$1";	1176	my $model = "AnyEvent::Impl::$1";
967	if (eval "require $model") {	1177	if (eval "require $model") {
968	$MODEL = $model;	1178	$MODEL = $model;
969	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1179	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
970	} else {	1180	} else {
971	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1181	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
972	}	1182	}
973	}	1183	}
974		1184
975	# check for already loaded models	1185	# check for already loaded models
976	unless ($MODEL) {	1186	unless ($MODEL) {
977	for (@REGISTRY, @models) {	1187	for (@REGISTRY, @models) {
978	my ($package, $model) = @$_;	1188	my ($package, $model) = @$_;
979	if (${"$package\::VERSION"} > 0) {	1189	if (${"$package\::VERSION"} > 0) {
980	if (eval "require $model") {	1190	if (eval "require $model") {
981	$MODEL = $model;	1191	$MODEL = $model;
982	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1192	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
983	last;	1193	last;
984	}	1194	}
985	}	1195	}
986	}	1196	}
987		1197
…		…
992	my ($package, $model) = @$_;	1202	my ($package, $model) = @$_;
993	if (eval "require $package"	1203	if (eval "require $package"
994	and ${"$package\::VERSION"} > 0	1204	and ${"$package\::VERSION"} > 0
995	and eval "require $model") {	1205	and eval "require $model") {
996	$MODEL = $model;	1206	$MODEL = $model;
997	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1207	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
998	last;	1208	last;
999	}	1209	}
1000	}	1210	}
1001		1211
1002	$MODEL	1212	$MODEL
…		…
1018		1228
1019	sub AUTOLOAD {	1229	sub AUTOLOAD {
1020	(my $func = $AUTOLOAD) =~ s/.*://;	1230	(my $func = $AUTOLOAD) =~ s/.*://;
1021		1231
1022	$method{$func}	1232	$method{$func}
1023	or croak "$func: not a valid method for AnyEvent objects";	1233	or Carp::croak "$func: not a valid method for AnyEvent objects";
1024		1234
1025	detect unless $MODEL;	1235	detect unless $MODEL;
1026		1236
1027	my $class = shift;	1237	my $class = shift;
1028	$class->$func (@_);	1238	$class->$func (@_);
1029	}	1239	}
1030		1240
1031	# utility function to dup a filehandle. this is used by many backends	1241	# utility function to dup a filehandle. this is used by many backends
1032	# to support binding more than one watcher per filehandle (they usually	1242	# to support binding more than one watcher per filehandle (they usually
1033	# allow only one watcher per fd, so we dup it to get a different one).	1243	# allow only one watcher per fd, so we dup it to get a different one).
1034	sub _dupfh($$$$) {	1244	sub _dupfh($$;$$) {
1035	my ($poll, $fh, $r, $w) = @_;	1245	my ($poll, $fh, $r, $w) = @_;
1036		1246
1037	# cygwin requires the fh mode to be matching, unix doesn't	1247	# cygwin requires the fh mode to be matching, unix doesn't
1038	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1248	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1039	: $poll eq "w" ? ($w, ">")
1040	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1041		1249
1042	open my $fh2, "$mode&" . fileno $fh	1250	open my $fh2, $mode, $fh
1043	or die "cannot dup() filehandle: $!,";	1251	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1044		1252
1045	# we assume CLOEXEC is already set by perl in all important cases	1253	# we assume CLOEXEC is already set by perl in all important cases
1046		1254
1047	($fh2, $rw)	1255	($fh2, $rw)
1048	}	1256	}
1049		1257
1050	package AnyEvent::Base;	1258	package AnyEvent::Base;
1051		1259
1052	# default implementations for many methods	1260	# default implementations for many methods
1053		1261
1054	BEGIN {	1262	sub _time {
		1263	# probe for availability of Time::HiRes
1055	if (eval "use Time::HiRes (); time (); 1") {	1264	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1265	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1056	*_time = \&Time::HiRes::time;	1266	*_time = \&Time::HiRes::time;
1057	# if (eval "use POSIX (); (POSIX::times())...	1267	# if (eval "use POSIX (); (POSIX::times())...
1058	} else {	1268	} else {
		1269	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1059	*_time = sub { time }; # epic fail	1270	*_time = sub { time }; # epic fail
1060	}	1271	}
		1272
		1273	&_time
1061	}	1274	}
1062		1275
1063	sub time { _time }	1276	sub time { _time }
1064	sub now { _time }	1277	sub now { _time }
1065	sub now_update { }	1278	sub now_update { }
1066		1279
1067	# default implementation for ->condvar	1280	# default implementation for ->condvar
1068		1281
1069	sub condvar {	1282	sub condvar {
1070	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1283	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1071	}	1284	}
1072		1285
1073	# default implementation for ->signal	1286	# default implementation for ->signal
1074		1287
		1288	our $HAVE_ASYNC_INTERRUPT;
1075	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1289	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1290	our (%SIG_ASY, %SIG_ASY_W);
		1291	our ($SIG_COUNT, $SIG_TW);
1076		1292
1077	sub _signal_exec {	1293	sub _signal_exec {
		1294	$HAVE_ASYNC_INTERRUPT
		1295	? $SIGPIPE_R->drain
1078	sysread $SIGPIPE_R, my $dummy, 4;	1296	: sysread $SIGPIPE_R, my $dummy, 9;
1079		1297
1080	while (%SIG_EV) {	1298	while (%SIG_EV) {
1081	for (keys %SIG_EV) {	1299	for (keys %SIG_EV) {
1082	delete $SIG_EV{$_};	1300	delete $SIG_EV{$_};
1083	$_->() for values %{ $SIG_CB{$_} || {} };	1301	$_->() for values %{ $SIG_CB{$_} || {} };
1084	}	1302	}
1085	}	1303	}
1086	}	1304	}
1087		1305
		1306	# install a dumym wakeupw atcher to reduce signal catching latency
		1307	sub _sig_add() {
		1308	unless ($SIG_COUNT++) {
		1309	# try to align timer on a full-second boundary, if possible
		1310	my $NOW = AnyEvent->now;
		1311
		1312	$SIG_TW = AnyEvent->timer (
		1313	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1314	interval => $MAX_SIGNAL_LATENCY,
		1315	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1316	);
		1317	}
		1318	}
		1319
		1320	sub _sig_del {
		1321	undef $SIG_TW
		1322	unless --$SIG_COUNT;
		1323	}
		1324
		1325	sub _signal {
		1326	my (undef, %arg) = @_;
		1327
		1328	my $signal = uc $arg{signal}
		1329	or Carp::croak "required option 'signal' is missing";
		1330
		1331	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1332
		1333	if ($HAVE_ASYNC_INTERRUPT) {
		1334	# async::interrupt
		1335
		1336	$SIG_ASY{$signal} ||= do {
		1337	my $asy = new Async::Interrupt
		1338	cb => sub { undef $SIG_EV{$signal} },
		1339	signal => $signal,
		1340	pipe => [$SIGPIPE_R->filenos],
		1341	;
		1342	$asy->pipe_autodrain (0);
		1343
		1344	$asy
		1345	};
		1346
		1347	} else {
		1348	# pure perl
		1349
		1350	$SIG{$signal} ||= sub {
		1351	local $!;
		1352	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1353	undef $SIG_EV{$signal};
		1354	};
		1355
		1356	# can't do signal processing without introducing races in pure perl,
		1357	# so limit the signal latency.
		1358	_sig_add;
		1359	}
		1360
		1361	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1362	}
		1363
1088	sub signal {	1364	sub signal {
1089	my (undef, %arg) = @_;	1365	# probe for availability of Async::Interrupt
		1366	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1367	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1090		1368
1091	unless ($SIGPIPE_R) {	1369	$HAVE_ASYNC_INTERRUPT = 1;
		1370	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1371	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1372
		1373	} else {
		1374	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1375
1092	require Fcntl;	1376	require Fcntl;
1093		1377
1094	if (AnyEvent::WIN32) {	1378	if (AnyEvent::WIN32) {
1095	require AnyEvent::Util;	1379	require AnyEvent::Util;
1096		1380
…		…
1099	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case	1383	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1100	} else {	1384	} else {
1101	pipe $SIGPIPE_R, $SIGPIPE_W;	1385	pipe $SIGPIPE_R, $SIGPIPE_W;
1102	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1386	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1103	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1387	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1388
		1389	# not strictly required, as $^F is normally 2, but let's make sure...
		1390	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1391	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1104	}	1392	}
1105		1393
1106	$SIGPIPE_R	1394	$SIGPIPE_R
1107	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1395	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1108		1396
1109	# not strictly required, as $^F is normally 2, but let's make sure...
1110	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1111	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1112
1113	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1397	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1114	}	1398	}
1115		1399
1116	my $signal = uc $arg{signal}	1400	*signal = \&_signal;
1117	or Carp::croak "required option 'signal' is missing";	1401	&signal
1118
1119	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1120	$SIG{$signal} ||= sub {
1121	local $!;
1122	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1123	undef $SIG_EV{$signal};
1124	};
1125
1126	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
1127	}	1402	}
1128		1403
1129	sub AnyEvent::Base::Signal::DESTROY {	1404	sub AnyEvent::Base::signal::DESTROY {
1130	my ($signal, $cb) = @{$_[0]};	1405	my ($signal, $cb) = @{$_[0]};
1131		1406
		1407	_sig_del;
		1408
1132	delete $SIG_CB{$signal}{$cb};	1409	delete $SIG_CB{$signal}{$cb};
1133		1410
		1411	$HAVE_ASYNC_INTERRUPT
		1412	? delete $SIG_ASY{$signal}
		1413	: # delete doesn't work with older perls - they then
		1414	# print weird messages, or just unconditionally exit
		1415	# instead of getting the default action.
		1416	undef $SIG{$signal}
1134	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1417	unless keys %{ $SIG_CB{$signal} };
1135	}	1418	}
1136		1419
1137	# default implementation for ->child	1420	# default implementation for ->child
1138		1421
1139	our %PID_CB;	1422	our %PID_CB;
1140	our $CHLD_W;	1423	our $CHLD_W;
1141	our $CHLD_DELAY_W;	1424	our $CHLD_DELAY_W;
1142	our $PID_IDLE;
1143	our $WNOHANG;	1425	our $WNOHANG;
1144		1426
1145	sub _child_wait {	1427	sub _sigchld {
1146	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1428	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1429	$_->($pid, $?)
1147	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1430	for values %{ $PID_CB{$pid} || {} },
1148	(values %{ $PID_CB{0} || {} });	1431	values %{ $PID_CB{0} || {} };
1149	}	1432	}
1150
1151	undef $PID_IDLE;
1152	}
1153
1154	sub _sigchld {
1155	# make sure we deliver these changes "synchronous" with the event loop.
1156	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1157	undef $CHLD_DELAY_W;
1158	&_child_wait;
1159	});
1160	}	1433	}
1161		1434
1162	sub child {	1435	sub child {
1163	my (undef, %arg) = @_;	1436	my (undef, %arg) = @_;
1164		1437
1165	defined (my $pid = $arg{pid} + 0)	1438	defined (my $pid = $arg{pid} + 0)
1166	or Carp::croak "required option 'pid' is missing";	1439	or Carp::croak "required option 'pid' is missing";
1167		1440
1168	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1441	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1169		1442
1170	unless ($WNOHANG) {	1443	# WNOHANG is almost cetrainly 1 everywhere
		1444	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1445	? 1
1171	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1446	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1172	}
1173		1447
1174	unless ($CHLD_W) {	1448	unless ($CHLD_W) {
1175	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1449	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1176	# child could be a zombie already, so make at least one round	1450	# child could be a zombie already, so make at least one round
1177	&_sigchld;	1451	&_sigchld;
1178	}	1452	}
1179		1453
1180	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1454	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1181	}	1455	}
1182		1456
1183	sub AnyEvent::Base::Child::DESTROY {	1457	sub AnyEvent::Base::child::DESTROY {
1184	my ($pid, $cb) = @{$_[0]};	1458	my ($pid, $cb) = @{$_[0]};
1185		1459
1186	delete $PID_CB{$pid}{$cb};	1460	delete $PID_CB{$pid}{$cb};
1187	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1461	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1188		1462
1189	undef $CHLD_W unless keys %PID_CB;	1463	undef $CHLD_W unless keys %PID_CB;
1190	}	1464	}
1191		1465
		1466	# idle emulation is done by simply using a timer, regardless
		1467	# of whether the process is idle or not, and not letting
		1468	# the callback use more than 50% of the time.
		1469	sub idle {
		1470	my (undef, %arg) = @_;
		1471
		1472	my ($cb, $w, $rcb) = $arg{cb};
		1473
		1474	$rcb = sub {
		1475	if ($cb) {
		1476	$w = _time;
		1477	&$cb;
		1478	$w = _time - $w;
		1479
		1480	# never use more then 50% of the time for the idle watcher,
		1481	# within some limits
		1482	$w = 0.0001 if $w < 0.0001;
		1483	$w = 5 if $w > 5;
		1484
		1485	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1486	} else {
		1487	# clean up...
		1488	undef $w;
		1489	undef $rcb;
		1490	}
		1491	};
		1492
		1493	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1494
		1495	bless \\$cb, "AnyEvent::Base::idle"
		1496	}
		1497
		1498	sub AnyEvent::Base::idle::DESTROY {
		1499	undef $${$_[0]};
		1500	}
		1501
1192	package AnyEvent::CondVar;	1502	package AnyEvent::CondVar;
1193		1503
1194	our @ISA = AnyEvent::CondVar::Base::;	1504	our @ISA = AnyEvent::CondVar::Base::;
1195		1505
1196	package AnyEvent::CondVar::Base;	1506	package AnyEvent::CondVar::Base;
1197		1507
1198	use overload	1508	#use overload
1199	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1509	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1200	fallback => 1;	1510	# fallback => 1;
		1511
		1512	# save 300+ kilobytes by dirtily hardcoding overloading
		1513	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1514	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1515	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1516	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1517
		1518	our $WAITING;
1201		1519
1202	sub _send {	1520	sub _send {
1203	# nop	1521	# nop
1204	}	1522	}
1205		1523
…		…
1218	sub ready {	1536	sub ready {
1219	$_[0]{_ae_sent}	1537	$_[0]{_ae_sent}
1220	}	1538	}
1221		1539
1222	sub _wait {	1540	sub _wait {
		1541	$WAITING
		1542	and !$_[0]{_ae_sent}
		1543	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1544
		1545	local $WAITING = 1;
1223	AnyEvent->one_event while !$_[0]{_ae_sent};	1546	AnyEvent->one_event while !$_[0]{_ae_sent};
1224	}	1547	}
1225		1548
1226	sub recv {	1549	sub recv {
1227	$_[0]->_wait;	1550	$_[0]->_wait;
…		…
1268	so on.	1591	so on.
1269		1592
1270	=head1 ENVIRONMENT VARIABLES	1593	=head1 ENVIRONMENT VARIABLES
1271		1594
1272	The following environment variables are used by this module or its	1595	The following environment variables are used by this module or its
1273	submodules:	1596	submodules.
		1597
		1598	Note that AnyEvent will remove I<all> environment variables starting with
		1599	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1600	enabled.
1274		1601
1275	=over 4	1602	=over 4
1276		1603
1277	=item C<PERL_ANYEVENT_VERBOSE>	1604	=item C<PERL_ANYEVENT_VERBOSE>
1278		1605
…		…
1285	C<PERL_ANYEVENT_MODEL>.	1612	C<PERL_ANYEVENT_MODEL>.
1286		1613
1287	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1614	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1288	model it chooses.	1615	model it chooses.
1289		1616
		1617	When set to C<8> or higher, then AnyEvent will report extra information on
		1618	which optional modules it loads and how it implements certain features.
		1619
1290	=item C<PERL_ANYEVENT_STRICT>	1620	=item C<PERL_ANYEVENT_STRICT>
1291		1621
1292	AnyEvent does not do much argument checking by default, as thorough	1622	AnyEvent does not do much argument checking by default, as thorough
1293	argument checking is very costly. Setting this variable to a true value	1623	argument checking is very costly. Setting this variable to a true value
1294	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1624	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1295	check the arguments passed to most method calls. If it finds any problems	1625	check the arguments passed to most method calls. If it finds any problems,
1296	it will croak.	1626	it will croak.
1297		1627
1298	In other words, enables "strict" mode.	1628	In other words, enables "strict" mode.
1299		1629
1300	Unlike C<use strict>, it is definitely recommended ot keep it off in	1630	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
1301	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1631	>>, it is definitely recommended to keep it off in production. Keeping
1302	developing programs can be very useful, however.	1632	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1633	can be very useful, however.
1303		1634
1304	=item C<PERL_ANYEVENT_MODEL>	1635	=item C<PERL_ANYEVENT_MODEL>
1305		1636
1306	This can be used to specify the event model to be used by AnyEvent, before	1637	This can be used to specify the event model to be used by AnyEvent, before
1307	auto detection and -probing kicks in. It must be a string consisting	1638	auto detection and -probing kicks in. It must be a string consisting
…		…
1350		1681
1351	=item C<PERL_ANYEVENT_MAX_FORKS>	1682	=item C<PERL_ANYEVENT_MAX_FORKS>
1352		1683
1353	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1684	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1354	will create in parallel.	1685	will create in parallel.
		1686
		1687	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1688
		1689	The default value for the C<max_outstanding> parameter for the default DNS
		1690	resolver - this is the maximum number of parallel DNS requests that are
		1691	sent to the DNS server.
		1692
		1693	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1694
		1695	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1696	configuration) in the default resolver. When set to the empty string, no
		1697	default config will be used.
		1698
		1699	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1700
		1701	When neither C<ca_file> nor C<ca_path> was specified during
		1702	L<AnyEvent::TLS> context creation, and either of these environment
		1703	variables exist, they will be used to specify CA certificate locations
		1704	instead of a system-dependent default.
		1705
		1706	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1707
		1708	When these are set to C<1>, then the respective modules are not
		1709	loaded. Mostly good for testing AnyEvent itself.
1355		1710
1356	=back	1711	=back
1357		1712
1358	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1713	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1359		1714
…		…
1604	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	1959	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1605	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	1960	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1606	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	1961	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1607	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	1962	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1608	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	1963	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1964	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1965	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1609	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	1966	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1610	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	1967	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1611	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	1968	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1612	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	1969	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1613		1970
…		…
1642	performance becomes really bad with lots of file descriptors (and few of	1999	performance becomes really bad with lots of file descriptors (and few of
1643	them active), of course, but this was not subject of this benchmark.	2000	them active), of course, but this was not subject of this benchmark.
1644		2001
1645	The C<Event> module has a relatively high setup and callback invocation	2002	The C<Event> module has a relatively high setup and callback invocation
1646	cost, but overall scores in on the third place.	2003	cost, but overall scores in on the third place.
		2004
		2005	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2006	when using its pure perl backend.
1647		2007
1648	C<Glib>'s memory usage is quite a bit higher, but it features a	2008	C<Glib>'s memory usage is quite a bit higher, but it features a
1649	faster callback invocation and overall ends up in the same class as	2009	faster callback invocation and overall ends up in the same class as
1650	C<Event>. However, Glib scales extremely badly, doubling the number of	2010	C<Event>. However, Glib scales extremely badly, doubling the number of
1651	watchers increases the processing time by more than a factor of four,	2011	watchers increases the processing time by more than a factor of four,
…		…
1729	it to another server. This includes deleting the old timeout and creating	2089	it to another server. This includes deleting the old timeout and creating
1730	a new one that moves the timeout into the future.	2090	a new one that moves the timeout into the future.
1731		2091
1732	=head3 Results	2092	=head3 Results
1733		2093
1734	name sockets create request	2094	name sockets create request
1735	EV 20000 69.01 11.16	2095	EV 20000 69.01 11.16
1736	Perl 20000 73.32 35.87	2096	Perl 20000 73.32 35.87
		2097	IOAsync 20000 157.00 98.14 epoll
		2098	IOAsync 20000 159.31 616.06 poll
1737	Event 20000 212.62 257.32	2099	Event 20000 212.62 257.32
1738	Glib 20000 651.16 1896.30	2100	Glib 20000 651.16 1896.30
1739	POE 20000 349.67 12317.24 uses POE::Loop::Event	2101	POE 20000 349.67 12317.24 uses POE::Loop::Event
1740		2102
1741	=head3 Discussion	2103	=head3 Discussion
1742		2104
1743	This benchmark I<does> measure scalability and overall performance of the	2105	This benchmark I<does> measure scalability and overall performance of the
1744	particular event loop.	2106	particular event loop.
…		…
1746	EV is again fastest. Since it is using epoll on my system, the setup time	2108	EV is again fastest. Since it is using epoll on my system, the setup time
1747	is relatively high, though.	2109	is relatively high, though.
1748		2110
1749	Perl surprisingly comes second. It is much faster than the C-based event	2111	Perl surprisingly comes second. It is much faster than the C-based event
1750	loops Event and Glib.	2112	loops Event and Glib.
		2113
		2114	IO::Async performs very well when using its epoll backend, and still quite
		2115	good compared to Glib when using its pure perl backend.
1751		2116
1752	Event suffers from high setup time as well (look at its code and you will	2117	Event suffers from high setup time as well (look at its code and you will
1753	understand why). Callback invocation also has a high overhead compared to	2118	understand why). Callback invocation also has a high overhead compared to
1754	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2119	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1755	uses select or poll in basically all documented configurations.	2120	uses select or poll in basically all documented configurations.
…		…
1818	=item * C-based event loops perform very well with small number of	2183	=item * C-based event loops perform very well with small number of
1819	watchers, as the management overhead dominates.	2184	watchers, as the management overhead dominates.
1820		2185
1821	=back	2186	=back
1822		2187
		2188	=head2 THE IO::Lambda BENCHMARK
		2189
		2190	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2191	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2192	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2193	shouldn't come as a surprise to anybody). As such, the benchmark is
		2194	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2195	very optimal. But how would AnyEvent compare when used without the extra
		2196	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2197
		2198	The benchmark itself creates an echo-server, and then, for 500 times,
		2199	connects to the echo server, sends a line, waits for the reply, and then
		2200	creates the next connection. This is a rather bad benchmark, as it doesn't
		2201	test the efficiency of the framework or much non-blocking I/O, but it is a
		2202	benchmark nevertheless.
		2203
		2204	name runtime
		2205	Lambda/select 0.330 sec
		2206	+ optimized 0.122 sec
		2207	Lambda/AnyEvent 0.327 sec
		2208	+ optimized 0.138 sec
		2209	Raw sockets/select 0.077 sec
		2210	POE/select, components 0.662 sec
		2211	POE/select, raw sockets 0.226 sec
		2212	POE/select, optimized 0.404 sec
		2213
		2214	AnyEvent/select/nb 0.085 sec
		2215	AnyEvent/EV/nb 0.068 sec
		2216	+state machine 0.134 sec
		2217
		2218	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2219	benchmarks actually make blocking connects and use 100% blocking I/O,
		2220	defeating the purpose of an event-based solution. All of the newly
		2221	written AnyEvent benchmarks use 100% non-blocking connects (using
		2222	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2223	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2224	generally require a lot more bookkeeping and event handling than blocking
		2225	connects (which involve a single syscall only).
		2226
		2227	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2228	offers similar expressive power as POE and IO::Lambda, using conventional
		2229	Perl syntax. This means that both the echo server and the client are 100%
		2230	non-blocking, further placing it at a disadvantage.
		2231
		2232	As you can see, the AnyEvent + EV combination even beats the
		2233	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2234	backend easily beats IO::Lambda and POE.
		2235
		2236	And even the 100% non-blocking version written using the high-level (and
		2237	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2238	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2239	in a non-blocking way.
		2240
		2241	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2242	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2243	part of the IO::lambda distribution and were used without any changes.
		2244
1823		2245
1824	=head1 SIGNALS	2246	=head1 SIGNALS
1825		2247
1826	AnyEvent currently installs handlers for these signals:	2248	AnyEvent currently installs handlers for these signals:
1827		2249
…		…
1830	=item SIGCHLD	2252	=item SIGCHLD
1831		2253
1832	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2254	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1833	emulation for event loops that do not support them natively. Also, some	2255	emulation for event loops that do not support them natively. Also, some
1834	event loops install a similar handler.	2256	event loops install a similar handler.
		2257
		2258	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2259	AnyEvent will reset it to default, to avoid losing child exit statuses.
1835		2260
1836	=item SIGPIPE	2261	=item SIGPIPE
1837		2262
1838	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2263	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1839	when AnyEvent gets loaded.	2264	when AnyEvent gets loaded.
…		…
1851		2276
1852	=back	2277	=back
1853		2278
1854	=cut	2279	=cut
1855		2280
		2281	undef $SIG{CHLD}
		2282	if $SIG{CHLD} eq 'IGNORE';
		2283
1856	$SIG{PIPE} = sub { }	2284	$SIG{PIPE} = sub { }
1857	unless defined $SIG{PIPE};	2285	unless defined $SIG{PIPE};
		2286
		2287	=head1 RECOMMENDED/OPTIONAL MODULES
		2288
		2289	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2290	it's built-in modules) are required to use it.
		2291
		2292	That does not mean that AnyEvent won't take advantage of some additional
		2293	modules if they are installed.
		2294
		2295	This section epxlains which additional modules will be used, and how they
		2296	affect AnyEvent's operetion.
		2297
		2298	=over 4
		2299
		2300	=item L<Async::Interrupt>
		2301
		2302	This slightly arcane module is used to implement fast signal handling: To
		2303	my knowledge, there is no way to do completely race-free and quick
		2304	signal handling in pure perl. To ensure that signals still get
		2305	delivered, AnyEvent will start an interval timer to wake up perl (and
		2306	catch the signals) with some delay (default is 10 seconds, look for
		2307	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2308
		2309	If this module is available, then it will be used to implement signal
		2310	catching, which means that signals will not be delayed, and the event loop
		2311	will not be interrupted regularly, which is more efficient (And good for
		2312	battery life on laptops).
		2313
		2314	This affects not just the pure-perl event loop, but also other event loops
		2315	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2316
		2317	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2318	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2319	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2320	does nothing for those backends.
		2321
		2322	=item L<EV>
		2323
		2324	This module isn't really "optional", as it is simply one of the backend
		2325	event loops that AnyEvent can use. However, it is simply the best event
		2326	loop available in terms of features, speed and stability: It supports
		2327	the AnyEvent API optimally, implements all the watcher types in XS, does
		2328	automatic timer adjustments even when no monotonic clock is available,
		2329	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2330	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2331	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2332
		2333	=item L<Guard>
		2334
		2335	The guard module, when used, will be used to implement
		2336	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2337	lot less memory), but otherwise doesn't affect guard operation much. It is
		2338	purely used for performance.
		2339
		2340	=item L<JSON> and L<JSON::XS>
		2341
		2342	This module is required when you want to read or write JSON data via
		2343	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2344	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2345
		2346	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2347	installed.
		2348
		2349	=item L<Net::SSLeay>
		2350
		2351	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2352	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2353	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2354
		2355	=item L<Time::HiRes>
		2356
		2357	This module is part of perl since release 5.008. It will be used when the
		2358	chosen event library does not come with a timing source on it's own. The
		2359	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2360	try to use a monotonic clock for timing stability.
		2361
		2362	=back
1858		2363
1859		2364
1860	=head1 FORK	2365	=head1 FORK
1861		2366
1862	Most event libraries are not fork-safe. The ones who are usually are	2367	Most event libraries are not fork-safe. The ones who are usually are
1863	because they rely on inefficient but fork-safe C<select> or C<poll>	2368	because they rely on inefficient but fork-safe C<select> or C<poll>
1864	calls. Only L<EV> is fully fork-aware.	2369	calls. Only L<EV> is fully fork-aware.
1865		2370
1866	If you have to fork, you must either do so I<before> creating your first	2371	If you have to fork, you must either do so I<before> creating your first
1867	watcher OR you must not use AnyEvent at all in the child.	2372	watcher OR you must not use AnyEvent at all in the child OR you must do
		2373	something completely out of the scope of AnyEvent.
1868		2374
1869		2375
1870	=head1 SECURITY CONSIDERATIONS	2376	=head1 SECURITY CONSIDERATIONS
1871		2377
1872	AnyEvent can be forced to load any event model via	2378	AnyEvent can be forced to load any event model via
…		…
1884	use AnyEvent;	2390	use AnyEvent;
1885		2391
1886	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2392	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1887	be used to probe what backend is used and gain other information (which is	2393	be used to probe what backend is used and gain other information (which is
1888	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2394	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1889	$ENV{PERL_ANYEGENT_STRICT}.	2395	$ENV{PERL_ANYEVENT_STRICT}.
		2396
		2397	Note that AnyEvent will remove I<all> environment variables starting with
		2398	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2399	enabled.
1890		2400
1891		2401
1892	=head1 BUGS	2402	=head1 BUGS
1893		2403
1894	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2404	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
…		…
1906	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2416	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1907		2417
1908	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2418	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1909	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2419	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1910	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2420	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1911	L<AnyEvent::Impl::POE>.	2421	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1912		2422
1913	Non-blocking file handles, sockets, TCP clients and	2423	Non-blocking file handles, sockets, TCP clients and
1914	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2424	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1915		2425
1916	Asynchronous DNS: L<AnyEvent::DNS>.	2426	Asynchronous DNS: L<AnyEvent::DNS>.
1917		2427
1918	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2428	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2429	L<Coro::Event>,
1919		2430
1920	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2431	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2432	L<AnyEvent::HTTP>.
1921		2433
1922		2434
1923	=head1 AUTHOR	2435	=head1 AUTHOR
1924		2436
1925	Marc Lehmann <schmorp@schmorp.de>	2437	Marc Lehmann <schmorp@schmorp.de>

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