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Revision 1.198 by root, Thu Mar 26 20:17:44 2009 UTC vs.
Revision 1.249 by root, Mon Jul 20 06:00:42 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> the Perl I<file handle> (I<not> file descriptor) to watch for events	189	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
174	(AnyEvent might or might not keep a reference to this file handle). C<poll>	190	for events (AnyEvent might or might not keep a reference to this file
		191	handle). Note that only file handles pointing to things for which
		192	non-blocking operation makes sense are allowed. This includes sockets,
		193	most character devices, pipes, fifos and so on, but not for example files
		194	or block devices.
		195
175	must be a string that is either C<r> or C<w>, which creates a watcher	196	C<poll> must be a string that is either C<r> or C<w>, which creates a
176	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the	197	watcher waiting for "r"eadable or "w"ritable events, respectively.
		198
177	callback to invoke each time the file handle becomes ready.	199	C<cb> is the callback to invoke each time the file handle becomes ready.
178		200
179	Although the callback might get passed parameters, their value and	201	Although the callback might get passed parameters, their value and
180	presence is undefined and you cannot rely on them. Portable AnyEvent	202	presence is undefined and you cannot rely on them. Portable AnyEvent
181	callbacks cannot use arguments passed to I/O watcher callbacks.	203	callbacks cannot use arguments passed to I/O watcher callbacks.
182		204
…		…
314	In either case, if you care (and in most cases, you don't), then you	336	In either case, if you care (and in most cases, you don't), then you
315	can get whatever behaviour you want with any event loop, by taking the	337	can get whatever behaviour you want with any event loop, by taking the
316	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	338	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
317	account.	339	account.
318		340
		341	=item AnyEvent->now_update
		342
		343	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		344	the current time for each loop iteration (see the discussion of L<<
		345	AnyEvent->now >>, above).
		346
		347	When a callback runs for a long time (or when the process sleeps), then
		348	this "current" time will differ substantially from the real time, which
		349	might affect timers and time-outs.
		350
		351	When this is the case, you can call this method, which will update the
		352	event loop's idea of "current time".
		353
		354	Note that updating the time I<might> cause some events to be handled.
		355
319	=back	356	=back
320		357
321	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
322		359
323	You can watch for signals using a signal watcher, C<signal> is the signal	360	You can watch for signals using a signal watcher, C<signal> is the signal
…		…
332	invocation, and callback invocation will be synchronous. Synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
333	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,
334	but it is guaranteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
335		372
336	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
337	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
338		376
339	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
340	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
341		380
342	Example: exit on SIGINT	381	Example: exit on SIGINT
343		382
344	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.
345		400
346	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
347		402
348	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.
349		404
…		…
363		418
364	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
365	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
366	have exited already (and no SIGCHLD will be sent anymore).	421	have exited already (and no SIGCHLD will be sent anymore).
367		422
368	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
369	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
370	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.
371		429
372	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
373	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
374	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.
375		438
376	Example: fork a process and wait for it	439	Example: fork a process and wait for it
377		440
378	my $done = AnyEvent->condvar;	441	my $done = AnyEvent->condvar;
379		442
…		…
389	);	452	);
390		453
391	# do something else, then wait for process exit	454	# do something else, then wait for process exit
392	$done->recv;	455	$done->recv;
393		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
394	=head2 CONDITION VARIABLES	492	=head2 CONDITION VARIABLES
395		493
396	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
397	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
398	will actively watch for new events and call your callbacks.	496	will actively watch for new events and call your callbacks.
399		497
400	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
401	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).
402		500
403	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
404	because they represent a condition that must become true.	502	because they represent a condition that must become true.
405		503
		504	Now is probably a good time to look at the examples further below.
		505
406	Condition variables can be created by calling the C<< AnyEvent->condvar	506	Condition variables can be created by calling the C<< AnyEvent->condvar
407	>> method, usually without arguments. The only argument pair allowed is	507	>> method, usually without arguments. The only argument pair allowed is
408
409	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
410	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
411	the results).	510	the results).
412		511
413	After creation, the condition variable is "false" until it becomes "true"	512	After creation, the condition variable is "false" until it becomes "true"
…		…
462	after => 1,	561	after => 1,
463	cb => sub { $result_ready->send },	562	cb => sub { $result_ready->send },
464	);	563	);
465		564
466	# this "blocks" (while handling events) till the callback	565	# this "blocks" (while handling events) till the callback
467	# calls send	566	# calls -<send
468	$result_ready->recv;	567	$result_ready->recv;
469		568
470	Example: wait for a timer, but take advantage of the fact that	569	Example: wait for a timer, but take advantage of the fact that condition
471	condition variables are also code references.	570	variables are also callable directly.
472		571
473	my $done = AnyEvent->condvar;	572	my $done = AnyEvent->condvar;
474	my $delay = AnyEvent->timer (after => 5, cb => $done);	573	my $delay = AnyEvent->timer (after => 5, cb => $done);
475	$done->recv;	574	$done->recv;
476		575
…		…
482		581
483	...	582	...
484		583
485	my @info = $couchdb->info->recv;	584	my @info = $couchdb->info->recv;
486		585
487	And this is how you would just ste a callback to be called whenever the	586	And this is how you would just set a callback to be called whenever the
488	results are available:	587	results are available:
489		588
490	$couchdb->info->cb (sub {	589	$couchdb->info->cb (sub {
491	my @info = $_[0]->recv;	590	my @info = $_[0]->recv;
492	});	591	});
…		…
510	immediately from within send.	609	immediately from within send.
511		610
512	Any arguments passed to the C<send> call will be returned by all	611	Any arguments passed to the C<send> call will be returned by all
513	future C<< ->recv >> calls.	612	future C<< ->recv >> calls.
514		613
515	Condition variables are overloaded so one can call them directly	614	Condition variables are overloaded so one can call them directly (as if
516	(as a code reference). Calling them directly is the same as calling	615	they were a code reference). Calling them directly is the same as calling
517	C<send>. Note, however, that many C-based event loops do not handle	616	C<send>.
518	overloading, so as tempting as it may be, passing a condition variable
519	instead of a callback does not work. Both the pure perl and EV loops
520	support overloading, however, as well as all functions that use perl to
521	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
522	example).
523		617
524	=item $cv->croak ($error)	618	=item $cv->croak ($error)
525		619
526	Similar to send, but causes all call's to C<< ->recv >> to invoke	620	Similar to send, but causes all call's to C<< ->recv >> to invoke
527	C<Carp::croak> with the given error message/object/scalar.	621	C<Carp::croak> with the given error message/object/scalar.
528		622
529	This can be used to signal any errors to the condition variable	623	This can be used to signal any errors to the condition variable
530	user/consumer.	624	user/consumer. Doing it this way instead of calling C<croak> directly
		625	delays the error detetcion, but has the overwhelmign advantage that it
		626	diagnoses the error at the place where the result is expected, and not
		627	deep in some event clalback without connection to the actual code causing
		628	the problem.
531		629
532	=item $cv->begin ([group callback])	630	=item $cv->begin ([group callback])
533		631
534	=item $cv->end	632	=item $cv->end
535
536	These two methods are EXPERIMENTAL and MIGHT CHANGE.
537		633
538	These two methods can be used to combine many transactions/events into	634	These two methods can be used to combine many transactions/events into
539	one. For example, a function that pings many hosts in parallel might want	635	one. For example, a function that pings many hosts in parallel might want
540	to use a condition variable for the whole process.	636	to use a condition variable for the whole process.
541		637
…		…
543	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	639	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
544	>>, the (last) callback passed to C<begin> will be executed. That callback	640	>>, the (last) callback passed to C<begin> will be executed. That callback
545	is I<supposed> to call C<< ->send >>, but that is not required. If no	641	is I<supposed> to call C<< ->send >>, but that is not required. If no
546	callback was set, C<send> will be called without any arguments.	642	callback was set, C<send> will be called without any arguments.
547		643
548	Let's clarify this with the ping example:	644	You can think of C<< $cv->send >> giving you an OR condition (one call
		645	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		646	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		647
		648	Let's start with a simple example: you have two I/O watchers (for example,
		649	STDOUT and STDERR for a program), and you want to wait for both streams to
		650	close before activating a condvar:
		651
		652	my $cv = AnyEvent->condvar;
		653
		654	$cv->begin; # first watcher
		655	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		656	defined sysread $fh1, my $buf, 4096
		657	or $cv->end;
		658	});
		659
		660	$cv->begin; # second watcher
		661	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		662	defined sysread $fh2, my $buf, 4096
		663	or $cv->end;
		664	});
		665
		666	$cv->recv;
		667
		668	This works because for every event source (EOF on file handle), there is
		669	one call to C<begin>, so the condvar waits for all calls to C<end> before
		670	sending.
		671
		672	The ping example mentioned above is slightly more complicated, as the
		673	there are results to be passwd back, and the number of tasks that are
		674	begung can potentially be zero:
549		675
550	my $cv = AnyEvent->condvar;	676	my $cv = AnyEvent->condvar;
551		677
552	my %result;	678	my %result;
553	$cv->begin (sub { $cv->send (\%result) });	679	$cv->begin (sub { $cv->send (\%result) });
…		…
573	loop, which serves two important purposes: first, it sets the callback	699	loop, which serves two important purposes: first, it sets the callback
574	to be called once the counter reaches C<0>, and second, it ensures that	700	to be called once the counter reaches C<0>, and second, it ensures that
575	C<send> is called even when C<no> hosts are being pinged (the loop	701	C<send> is called even when C<no> hosts are being pinged (the loop
576	doesn't execute once).	702	doesn't execute once).
577		703
578	This is the general pattern when you "fan out" into multiple subrequests:	704	This is the general pattern when you "fan out" into multiple (but
579	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	705	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
580	is called at least once, and then, for each subrequest you start, call	706	the callback and ensure C<end> is called at least once, and then, for each
581	C<begin> and for each subrequest you finish, call C<end>.	707	subrequest you start, call C<begin> and for each subrequest you finish,
		708	call C<end>.
582		709
583	=back	710	=back
584		711
585	=head3 METHODS FOR CONSUMERS	712	=head3 METHODS FOR CONSUMERS
586		713
…		…
602	function will call C<croak>.	729	function will call C<croak>.
603		730
604	In list context, all parameters passed to C<send> will be returned,	731	In list context, all parameters passed to C<send> will be returned,
605	in scalar context only the first one will be returned.	732	in scalar context only the first one will be returned.
606		733
		734	Note that doing a blocking wait in a callback is not supported by any
		735	event loop, that is, recursive invocation of a blocking C<< ->recv
		736	>> is not allowed, and the C<recv> call will C<croak> if such a
		737	condition is detected. This condition can be slightly loosened by using
		738	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		739	any thread that doesn't run the event loop itself.
		740
607	Not all event models support a blocking wait - some die in that case	741	Not all event models support a blocking wait - some die in that case
608	(programs might want to do that to stay interactive), so I<if you are	742	(programs might want to do that to stay interactive), so I<if you are
609	using this from a module, never require a blocking wait>, but let the	743	using this from a module, never require a blocking wait>. Instead, let the
610	caller decide whether the call will block or not (for example, by coupling	744	caller decide whether the call will block or not (for example, by coupling
611	condition variables with some kind of request results and supporting	745	condition variables with some kind of request results and supporting
612	callbacks so the caller knows that getting the result will not block,	746	callbacks so the caller knows that getting the result will not block,
613	while still supporting blocking waits if the caller so desires).	747	while still supporting blocking waits if the caller so desires).
614		748
615	Another reason I<never> to C<< ->recv >> in a module is that you cannot
616	sensibly have two C<< ->recv >>'s in parallel, as that would require
617	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
618	can supply.
619
620	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
621	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
622	versions and also integrates coroutines into AnyEvent, making blocking
623	C<< ->recv >> calls perfectly safe as long as they are done from another
624	coroutine (one that doesn't run the event loop).
625
626	You can ensure that C<< -recv >> never blocks by setting a callback and	749	You can ensure that C<< -recv >> never blocks by setting a callback and
627	only calling C<< ->recv >> from within that callback (or at a later	750	only calling C<< ->recv >> from within that callback (or at a later
628	time). This will work even when the event loop does not support blocking	751	time). This will work even when the event loop does not support blocking
629	waits otherwise.	752	waits otherwise.
630		753
…		…
643	variable itself. Calling C<recv> inside the callback or at any later time	766	variable itself. Calling C<recv> inside the callback or at any later time
644	is guaranteed not to block.	767	is guaranteed not to block.
645		768
646	=back	769	=back
647		770
		771	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		772
		773	The available backend classes are (every class has its own manpage):
		774
		775	=over 4
		776
		777	=item Backends that are autoprobed when no other event loop can be found.
		778
		779	EV is the preferred backend when no other event loop seems to be in
		780	use. If EV is not installed, then AnyEvent will try Event, and, failing
		781	that, will fall back to its own pure-perl implementation, which is
		782	available everywhere as it comes with AnyEvent itself.
		783
		784	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		785	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		786	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		787
		788	=item Backends that are transparently being picked up when they are used.
		789
		790	These will be used when they are currently loaded when the first watcher
		791	is created, in which case it is assumed that the application is using
		792	them. This means that AnyEvent will automatically pick the right backend
		793	when the main program loads an event module before anything starts to
		794	create watchers. Nothing special needs to be done by the main program.
		795
		796	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		797	AnyEvent::Impl::Tk based on Tk, very broken.
		798	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		799	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		800
		801	=item Backends with special needs.
		802
		803	Qt requires the Qt::Application to be instantiated first, but will
		804	otherwise be picked up automatically. As long as the main program
		805	instantiates the application before any AnyEvent watchers are created,
		806	everything should just work.
		807
		808	AnyEvent::Impl::Qt based on Qt.
		809
		810	Support for IO::Async can only be partial, as it is too broken and
		811	architecturally limited to even support the AnyEvent API. It also
		812	is the only event loop that needs the loop to be set explicitly, so
		813	it can only be used by a main program knowing about AnyEvent. See
		814	L<AnyEvent::Impl::Async> for the gory details.
		815
		816	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		817
		818	=item Event loops that are indirectly supported via other backends.
		819
		820	Some event loops can be supported via other modules:
		821
		822	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		823
		824	B<WxWidgets> has no support for watching file handles. However, you can
		825	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		826	polls 20 times per second, which was considered to be too horrible to even
		827	consider for AnyEvent.
		828
		829	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		830	backend, so it can be supported through POE.
		831
		832	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		833	load L<POE> when detecting them, in the hope that POE will pick them up,
		834	in which case everything will be automatic.
		835
		836	=back
		837
648	=head1 GLOBAL VARIABLES AND FUNCTIONS	838	=head1 GLOBAL VARIABLES AND FUNCTIONS
649		839
		840	These are not normally required to use AnyEvent, but can be useful to
		841	write AnyEvent extension modules.
		842
650	=over 4	843	=over 4
651		844
652	=item $AnyEvent::MODEL	845	=item $AnyEvent::MODEL
653		846
654	Contains C<undef> until the first watcher is being created. Then it	847	Contains C<undef> until the first watcher is being created, before the
		848	backend has been autodetected.
		849
655	contains the event model that is being used, which is the name of the	850	Afterwards it contains the event model that is being used, which is the
656	Perl class implementing the model. This class is usually one of the	851	name of the Perl class implementing the model. This class is usually one
657	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	852	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
658	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	853	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
659		854	will be C<urxvt::anyevent>).
660	The known classes so far are:
661
662	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
663	AnyEvent::Impl::Event based on Event, second best choice.
664	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
665	AnyEvent::Impl::Glib based on Glib, third-best choice.
666	AnyEvent::Impl::Tk based on Tk, very bad choice.
667	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
668	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
669	AnyEvent::Impl::POE based on POE, not generic enough for full support.
670
671	There is no support for WxWidgets, as WxWidgets has no support for
672	watching file handles. However, you can use WxWidgets through the
673	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
674	second, which was considered to be too horrible to even consider for
675	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
676	it's adaptor.
677
678	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
679	autodetecting them.
680		855
681	=item AnyEvent::detect	856	=item AnyEvent::detect
682		857
683	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	858	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
684	if necessary. You should only call this function right before you would	859	if necessary. You should only call this function right before you would
685	have created an AnyEvent watcher anyway, that is, as late as possible at	860	have created an AnyEvent watcher anyway, that is, as late as possible at
686	runtime.	861	runtime, and not e.g. while initialising of your module.
		862
		863	If you need to do some initialisation before AnyEvent watchers are
		864	created, use C<post_detect>.
687		865
688	=item $guard = AnyEvent::post_detect { BLOCK }	866	=item $guard = AnyEvent::post_detect { BLOCK }
689		867
690	Arranges for the code block to be executed as soon as the event model is	868	Arranges for the code block to be executed as soon as the event model is
691	autodetected (or immediately if this has already happened).	869	autodetected (or immediately if this has already happened).
		870
		871	The block will be executed I<after> the actual backend has been detected
		872	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		873	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		874	other initialisations - see the sources of L<AnyEvent::Strict> or
		875	L<AnyEvent::AIO> to see how this is used.
		876
		877	The most common usage is to create some global watchers, without forcing
		878	event module detection too early, for example, L<AnyEvent::AIO> creates
		879	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		880	avoid autodetecting the event module at load time.
692		881
693	If called in scalar or list context, then it creates and returns an object	882	If called in scalar or list context, then it creates and returns an object
694	that automatically removes the callback again when it is destroyed. See	883	that automatically removes the callback again when it is destroyed. See
695	L<Coro::BDB> for a case where this is useful.	884	L<Coro::BDB> for a case where this is useful.
696		885
…		…
699	If there are any code references in this array (you can C<push> to it	888	If there are any code references in this array (you can C<push> to it
700	before or after loading AnyEvent), then they will called directly after	889	before or after loading AnyEvent), then they will called directly after
701	the event loop has been chosen.	890	the event loop has been chosen.
702		891
703	You should check C<$AnyEvent::MODEL> before adding to this array, though:	892	You should check C<$AnyEvent::MODEL> before adding to this array, though:
704	if it contains a true value then the event loop has already been detected,	893	if it is defined then the event loop has already been detected, and the
705	and the array will be ignored.	894	array will be ignored.
706		895
707	Best use C<AnyEvent::post_detect { BLOCK }> instead.	896	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		897	it,as it takes care of these details.
		898
		899	This variable is mainly useful for modules that can do something useful
		900	when AnyEvent is used and thus want to know when it is initialised, but do
		901	not need to even load it by default. This array provides the means to hook
		902	into AnyEvent passively, without loading it.
708		903
709	=back	904	=back
710		905
711	=head1 WHAT TO DO IN A MODULE	906	=head1 WHAT TO DO IN A MODULE
712		907
…		…
767		962
768		963
769	=head1 OTHER MODULES	964	=head1 OTHER MODULES
770		965
771	The following is a non-exhaustive list of additional modules that use	966	The following is a non-exhaustive list of additional modules that use
772	AnyEvent and can therefore be mixed easily with other AnyEvent modules	967	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
773	in the same program. Some of the modules come with AnyEvent, some are	968	modules and other event loops in the same program. Some of the modules
774	available via CPAN.	969	come with AnyEvent, most are available via CPAN.
775		970
776	=over 4	971	=over 4
777		972
778	=item L<AnyEvent::Util>	973	=item L<AnyEvent::Util>
779		974
…		…
788		983
789	=item L<AnyEvent::Handle>	984	=item L<AnyEvent::Handle>
790		985
791	Provide read and write buffers, manages watchers for reads and writes,	986	Provide read and write buffers, manages watchers for reads and writes,
792	supports raw and formatted I/O, I/O queued and fully transparent and	987	supports raw and formatted I/O, I/O queued and fully transparent and
793	non-blocking SSL/TLS.	988	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
794		989
795	=item L<AnyEvent::DNS>	990	=item L<AnyEvent::DNS>
796		991
797	Provides rich asynchronous DNS resolver capabilities.	992	Provides rich asynchronous DNS resolver capabilities.
798		993
…		…
826		1021
827	=item L<AnyEvent::GPSD>	1022	=item L<AnyEvent::GPSD>
828		1023
829	A non-blocking interface to gpsd, a daemon delivering GPS information.	1024	A non-blocking interface to gpsd, a daemon delivering GPS information.
830		1025
		1026	=item L<AnyEvent::IRC>
		1027
		1028	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1029
		1030	=item L<AnyEvent::XMPP>
		1031
		1032	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1033	Net::XMPP2>.
		1034
831	=item L<AnyEvent::IGS>	1035	=item L<AnyEvent::IGS>
832		1036
833	A non-blocking interface to the Internet Go Server protocol (used by	1037	A non-blocking interface to the Internet Go Server protocol (used by
834	L<App::IGS>).	1038	L<App::IGS>).
835		1039
836	=item L<AnyEvent::IRC>
837
838	AnyEvent based IRC client module family (replacing the older Net::IRC3).
839
840	=item L<Net::XMPP2>
841
842	AnyEvent based XMPP (Jabber protocol) module family.
843
844	=item L<Net::FCP>	1040	=item L<Net::FCP>
845		1041
846	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1042	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
847	of AnyEvent.	1043	of AnyEvent.
848		1044
…		…
852		1048
853	=item L<Coro>	1049	=item L<Coro>
854		1050
855	Has special support for AnyEvent via L<Coro::AnyEvent>.	1051	Has special support for AnyEvent via L<Coro::AnyEvent>.
856		1052
857	=item L<IO::Lambda>
858
859	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
860
861	=back	1053	=back
862		1054
863	=cut	1055	=cut
864		1056
865	package AnyEvent;	1057	package AnyEvent;
866		1058
		1059	# basically a tuned-down version of common::sense
		1060	sub common_sense {
867	no warnings;	1061	# no warnings
		1062	${^WARNING_BITS} ^= ${^WARNING_BITS};
868	use strict qw(vars subs);	1063	# use strict vars subs
		1064	$^H |= 0x00000600;
		1065	}
869		1066
		1067	BEGIN { AnyEvent::common_sense }
		1068
870	use Carp;	1069	use Carp ();
871		1070
872	our $VERSION = 4.341;	1071	our $VERSION = 4.85;
873	our $MODEL;	1072	our $MODEL;
874		1073
875	our $AUTOLOAD;	1074	our $AUTOLOAD;
876	our @ISA;	1075	our @ISA;
877		1076
878	our @REGISTRY;	1077	our @REGISTRY;
879		1078
880	our $WIN32;	1079	our $WIN32;
881		1080
		1081	our $VERBOSE;
		1082
882	BEGIN {	1083	BEGIN {
883	my $win32 = ! ! ($^O =~ /mswin32/i);	1084	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
884	eval "sub WIN32(){ $win32 }";	1085	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
885	}
886		1086
		1087	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1088	if ${^TAINT};
		1089
887	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1090	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1091
		1092	}
		1093
		1094	our $MAX_SIGNAL_LATENCY = 10;
888		1095
889	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1096	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
890		1097
891	{	1098	{
892	my $idx;	1099	my $idx;
…		…
900	[Event:: => AnyEvent::Impl::Event::],	1107	[Event:: => AnyEvent::Impl::Event::],
901	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1108	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
902	# everything below here will not be autoprobed	1109	# everything below here will not be autoprobed
903	# as the pureperl backend should work everywhere	1110	# as the pureperl backend should work everywhere
904	# and is usually faster	1111	# and is usually faster
905	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
906	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1112	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
907	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1113	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1114	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
908	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1115	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
909	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1116	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
910	[Wx:: => AnyEvent::Impl::POE::],	1117	[Wx:: => AnyEvent::Impl::POE::],
911	[Prima:: => AnyEvent::Impl::POE::],	1118	[Prima:: => AnyEvent::Impl::POE::],
		1119	# IO::Async is just too broken - we would need workarounds for its
		1120	# byzantine signal and broken child handling, among others.
		1121	# IO::Async is rather hard to detect, as it doesn't have any
		1122	# obvious default class.
		1123	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1124	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1125	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
912	);	1126	);
913		1127
914	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1128	our %method = map +($_ => 1),
		1129	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
915		1130
916	our @post_detect;	1131	our @post_detect;
917		1132
918	sub post_detect(&) {	1133	sub post_detect(&) {
919	my ($cb) = @_;	1134	my ($cb) = @_;
…		…
924	1	1139	1
925	} else {	1140	} else {
926	push @post_detect, $cb;	1141	push @post_detect, $cb;
927		1142
928	defined wantarray	1143	defined wantarray
929	? bless \$cb, "AnyEvent::Util::PostDetect"	1144	? bless \$cb, "AnyEvent::Util::postdetect"
930	: ()	1145	: ()
931	}	1146	}
932	}	1147	}
933		1148
934	sub AnyEvent::Util::PostDetect::DESTROY {	1149	sub AnyEvent::Util::postdetect::DESTROY {
935	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1150	@post_detect = grep $_ != ${$_[0]}, @post_detect;
936	}	1151	}
937		1152
938	sub detect() {	1153	sub detect() {
939	unless ($MODEL) {	1154	unless ($MODEL) {
940	no strict 'refs';
941	local $SIG{__DIE__};	1155	local $SIG{__DIE__};
942		1156
943	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1157	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
944	my $model = "AnyEvent::Impl::$1";	1158	my $model = "AnyEvent::Impl::$1";
945	if (eval "require $model") {	1159	if (eval "require $model") {
946	$MODEL = $model;	1160	$MODEL = $model;
947	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1161	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
948	} else {	1162	} else {
949	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1163	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
950	}	1164	}
951	}	1165	}
952		1166
953	# check for already loaded models	1167	# check for already loaded models
954	unless ($MODEL) {	1168	unless ($MODEL) {
955	for (@REGISTRY, @models) {	1169	for (@REGISTRY, @models) {
956	my ($package, $model) = @$_;	1170	my ($package, $model) = @$_;
957	if (${"$package\::VERSION"} > 0) {	1171	if (${"$package\::VERSION"} > 0) {
958	if (eval "require $model") {	1172	if (eval "require $model") {
959	$MODEL = $model;	1173	$MODEL = $model;
960	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1174	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
961	last;	1175	last;
962	}	1176	}
963	}	1177	}
964	}	1178	}
965		1179
…		…
970	my ($package, $model) = @$_;	1184	my ($package, $model) = @$_;
971	if (eval "require $package"	1185	if (eval "require $package"
972	and ${"$package\::VERSION"} > 0	1186	and ${"$package\::VERSION"} > 0
973	and eval "require $model") {	1187	and eval "require $model") {
974	$MODEL = $model;	1188	$MODEL = $model;
975	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1189	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
976	last;	1190	last;
977	}	1191	}
978	}	1192	}
979		1193
980	$MODEL	1194	$MODEL
981	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1195	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
982	}	1196	}
983	}	1197	}
984		1198
985	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1199	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
986		1200
…		…
996		1210
997	sub AUTOLOAD {	1211	sub AUTOLOAD {
998	(my $func = $AUTOLOAD) =~ s/.*://;	1212	(my $func = $AUTOLOAD) =~ s/.*://;
999		1213
1000	$method{$func}	1214	$method{$func}
1001	or croak "$func: not a valid method for AnyEvent objects";	1215	or Carp::croak "$func: not a valid method for AnyEvent objects";
1002		1216
1003	detect unless $MODEL;	1217	detect unless $MODEL;
1004		1218
1005	my $class = shift;	1219	my $class = shift;
1006	$class->$func (@_);	1220	$class->$func (@_);
1007	}	1221	}
1008		1222
1009	# utility function to dup a filehandle. this is used by many backends	1223	# utility function to dup a filehandle. this is used by many backends
1010	# to support binding more than one watcher per filehandle (they usually	1224	# to support binding more than one watcher per filehandle (they usually
1011	# allow only one watcher per fd, so we dup it to get a different one).	1225	# allow only one watcher per fd, so we dup it to get a different one).
1012	sub _dupfh($$$$) {	1226	sub _dupfh($$;$$) {
1013	my ($poll, $fh, $r, $w) = @_;	1227	my ($poll, $fh, $r, $w) = @_;
1014		1228
1015	# cygwin requires the fh mode to be matching, unix doesn't	1229	# cygwin requires the fh mode to be matching, unix doesn't
1016	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1230	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1017	: $poll eq "w" ? ($w, ">")
1018	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1019		1231
1020	open my $fh2, "$mode&" . fileno $fh	1232	open my $fh2, $mode, $fh
1021	or die "cannot dup() filehandle: $!";	1233	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1022		1234
1023	# we assume CLOEXEC is already set by perl in all important cases	1235	# we assume CLOEXEC is already set by perl in all important cases
1024		1236
1025	($fh2, $rw)	1237	($fh2, $rw)
1026	}	1238	}
1027		1239
1028	package AnyEvent::Base;	1240	package AnyEvent::Base;
1029		1241
1030	# default implementation for now and time	1242	# default implementations for many methods
1031		1243
1032	BEGIN {	1244	sub _time {
		1245	# probe for availability of Time::HiRes
1033	if (eval "use Time::HiRes (); time (); 1") {	1246	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1247	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1034	*_time = \&Time::HiRes::time;	1248	*_time = \&Time::HiRes::time;
1035	# if (eval "use POSIX (); (POSIX::times())...	1249	# if (eval "use POSIX (); (POSIX::times())...
1036	} else {	1250	} else {
		1251	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1037	*_time = sub { time }; # epic fail	1252	*_time = sub { time }; # epic fail
1038	}	1253	}
		1254
		1255	&_time
1039	}	1256	}
1040		1257
1041	sub time { _time }	1258	sub time { _time }
1042	sub now { _time }	1259	sub now { _time }
		1260	sub now_update { }
1043		1261
1044	# default implementation for ->condvar	1262	# default implementation for ->condvar
1045		1263
1046	sub condvar {	1264	sub condvar {
1047	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1265	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1048	}	1266	}
1049		1267
1050	# default implementation for ->signal	1268	# default implementation for ->signal
1051		1269
		1270	our $HAVE_ASYNC_INTERRUPT;
1052	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1271	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1272	our (%SIG_ASY, %SIG_ASY_W);
		1273	our ($SIG_COUNT, $SIG_TW);
1053		1274
1054	sub _signal_exec {	1275	sub _signal_exec {
		1276	$HAVE_ASYNC_INTERRUPT
		1277	? $SIGPIPE_R->drain
1055	sysread $SIGPIPE_R, my $dummy, 4;	1278	: sysread $SIGPIPE_R, my $dummy, 9;
1056		1279
1057	while (%SIG_EV) {	1280	while (%SIG_EV) {
1058	for (keys %SIG_EV) {	1281	for (keys %SIG_EV) {
1059	delete $SIG_EV{$_};	1282	delete $SIG_EV{$_};
1060	$_->() for values %{ $SIG_CB{$_} || {} };	1283	$_->() for values %{ $SIG_CB{$_} || {} };
1061	}	1284	}
1062	}	1285	}
1063	}	1286	}
1064		1287
		1288	# install a dumym wakeupw atcher to reduce signal catching latency
		1289	sub _sig_add() {
		1290	unless ($SIG_COUNT++) {
		1291	# try to align timer on a full-second boundary, if possible
		1292	my $NOW = AnyEvent->now;
		1293
		1294	$SIG_TW = AnyEvent->timer (
		1295	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1296	interval => $MAX_SIGNAL_LATENCY,
		1297	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1298	);
		1299	}
		1300	}
		1301
		1302	sub _sig_del {
		1303	undef $SIG_TW
		1304	unless --$SIG_COUNT;
		1305	}
		1306
		1307	sub _signal {
		1308	my (undef, %arg) = @_;
		1309
		1310	my $signal = uc $arg{signal}
		1311	or Carp::croak "required option 'signal' is missing";
		1312
		1313	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1314
		1315	if ($HAVE_ASYNC_INTERRUPT) {
		1316	# async::interrupt
		1317
		1318	$SIG_ASY{$signal} ||= do {
		1319	my $asy = new Async::Interrupt
		1320	cb => sub { undef $SIG_EV{$signal} },
		1321	signal => $signal,
		1322	pipe => [$SIGPIPE_R->filenos],
		1323	;
		1324	$asy->pipe_autodrain (0);
		1325
		1326	$asy
		1327	};
		1328
		1329	} else {
		1330	# pure perl
		1331
		1332	$SIG{$signal} ||= sub {
		1333	local $!;
		1334	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1335	undef $SIG_EV{$signal};
		1336	};
		1337
		1338	# can't do signal processing without introducing races in pure perl,
		1339	# so limit the signal latency.
		1340	_sig_add;
		1341	}
		1342
		1343	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1344	}
		1345
1065	sub signal {	1346	sub signal {
1066	my (undef, %arg) = @_;	1347	# probe for availability of Async::Interrupt
		1348	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1349	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1067		1350
1068	unless ($SIGPIPE_R) {	1351	$HAVE_ASYNC_INTERRUPT = 1;
		1352	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1353	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1354
		1355	} else {
		1356	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1357
		1358	require Fcntl;
		1359
1069	if (AnyEvent::WIN32) {	1360	if (AnyEvent::WIN32) {
		1361	require AnyEvent::Util;
		1362
1070	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();	1363	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1071	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;	1364	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1072	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case	1365	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1073	} else {	1366	} else {
1074	pipe $SIGPIPE_R, $SIGPIPE_W;	1367	pipe $SIGPIPE_R, $SIGPIPE_W;
1075	require Fcntl;
1076	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1368	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1077	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1369	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1370
		1371	# not strictly required, as $^F is normally 2, but let's make sure...
		1372	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1373	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1078	}	1374	}
1079		1375
1080	$SIGPIPE_R	1376	$SIGPIPE_R
1081	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1377	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1082		1378
1083	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1379	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1084	}	1380	}
1085		1381
1086	my $signal = uc $arg{signal}	1382	*signal = \&_signal;
1087	or Carp::croak "required option 'signal' is missing";	1383	&signal
1088
1089	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1090	$SIG{$signal} ||= sub {
1091	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1092	undef $SIG_EV{$signal};
1093	};
1094
1095	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
1096	}	1384	}
1097		1385
1098	sub AnyEvent::Base::Signal::DESTROY {	1386	sub AnyEvent::Base::signal::DESTROY {
1099	my ($signal, $cb) = @{$_[0]};	1387	my ($signal, $cb) = @{$_[0]};
1100		1388
		1389	_sig_del;
		1390
1101	delete $SIG_CB{$signal}{$cb};	1391	delete $SIG_CB{$signal}{$cb};
1102		1392
		1393	$HAVE_ASYNC_INTERRUPT
		1394	? delete $SIG_ASY{$signal}
		1395	: # delete doesn't work with older perls - they then
		1396	# print weird messages, or just unconditionally exit
		1397	# instead of getting the default action.
		1398	undef $SIG{$signal}
1103	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1399	unless keys %{ $SIG_CB{$signal} };
1104	}	1400	}
1105		1401
1106	# default implementation for ->child	1402	# default implementation for ->child
1107		1403
1108	our %PID_CB;	1404	our %PID_CB;
1109	our $CHLD_W;	1405	our $CHLD_W;
1110	our $CHLD_DELAY_W;	1406	our $CHLD_DELAY_W;
1111	our $PID_IDLE;
1112	our $WNOHANG;	1407	our $WNOHANG;
1113		1408
1114	sub _child_wait {	1409	sub _sigchld {
1115	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1410	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1411	$_->($pid, $?)
1116	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1412	for values %{ $PID_CB{$pid} || {} },
1117	(values %{ $PID_CB{0} || {} });	1413	values %{ $PID_CB{0} || {} };
1118	}	1414	}
1119
1120	undef $PID_IDLE;
1121	}
1122
1123	sub _sigchld {
1124	# make sure we deliver these changes "synchronous" with the event loop.
1125	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1126	undef $CHLD_DELAY_W;
1127	&_child_wait;
1128	});
1129	}	1415	}
1130		1416
1131	sub child {	1417	sub child {
1132	my (undef, %arg) = @_;	1418	my (undef, %arg) = @_;
1133		1419
1134	defined (my $pid = $arg{pid} + 0)	1420	defined (my $pid = $arg{pid} + 0)
1135	or Carp::croak "required option 'pid' is missing";	1421	or Carp::croak "required option 'pid' is missing";
1136		1422
1137	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1423	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1138		1424
1139	unless ($WNOHANG) {	1425	# WNOHANG is almost cetrainly 1 everywhere
		1426	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1427	? 1
1140	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1428	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1141	}
1142		1429
1143	unless ($CHLD_W) {	1430	unless ($CHLD_W) {
1144	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1431	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1145	# child could be a zombie already, so make at least one round	1432	# child could be a zombie already, so make at least one round
1146	&_sigchld;	1433	&_sigchld;
1147	}	1434	}
1148		1435
1149	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1436	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1150	}	1437	}
1151		1438
1152	sub AnyEvent::Base::Child::DESTROY {	1439	sub AnyEvent::Base::child::DESTROY {
1153	my ($pid, $cb) = @{$_[0]};	1440	my ($pid, $cb) = @{$_[0]};
1154		1441
1155	delete $PID_CB{$pid}{$cb};	1442	delete $PID_CB{$pid}{$cb};
1156	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1443	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1157		1444
1158	undef $CHLD_W unless keys %PID_CB;	1445	undef $CHLD_W unless keys %PID_CB;
1159	}	1446	}
1160		1447
		1448	# idle emulation is done by simply using a timer, regardless
		1449	# of whether the process is idle or not, and not letting
		1450	# the callback use more than 50% of the time.
		1451	sub idle {
		1452	my (undef, %arg) = @_;
		1453
		1454	my ($cb, $w, $rcb) = $arg{cb};
		1455
		1456	$rcb = sub {
		1457	if ($cb) {
		1458	$w = _time;
		1459	&$cb;
		1460	$w = _time - $w;
		1461
		1462	# never use more then 50% of the time for the idle watcher,
		1463	# within some limits
		1464	$w = 0.0001 if $w < 0.0001;
		1465	$w = 5 if $w > 5;
		1466
		1467	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1468	} else {
		1469	# clean up...
		1470	undef $w;
		1471	undef $rcb;
		1472	}
		1473	};
		1474
		1475	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1476
		1477	bless \\$cb, "AnyEvent::Base::idle"
		1478	}
		1479
		1480	sub AnyEvent::Base::idle::DESTROY {
		1481	undef $${$_[0]};
		1482	}
		1483
1161	package AnyEvent::CondVar;	1484	package AnyEvent::CondVar;
1162		1485
1163	our @ISA = AnyEvent::CondVar::Base::;	1486	our @ISA = AnyEvent::CondVar::Base::;
1164		1487
1165	package AnyEvent::CondVar::Base;	1488	package AnyEvent::CondVar::Base;
1166		1489
1167	use overload	1490	#use overload
1168	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1491	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1169	fallback => 1;	1492	# fallback => 1;
		1493
		1494	# save 300+ kilobytes by dirtily hardcoding overloading
		1495	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1496	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1497	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1498	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1499
		1500	our $WAITING;
1170		1501
1171	sub _send {	1502	sub _send {
1172	# nop	1503	# nop
1173	}	1504	}
1174		1505
…		…
1187	sub ready {	1518	sub ready {
1188	$_[0]{_ae_sent}	1519	$_[0]{_ae_sent}
1189	}	1520	}
1190		1521
1191	sub _wait {	1522	sub _wait {
		1523	$WAITING
		1524	and !$_[0]{_ae_sent}
		1525	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1526
		1527	local $WAITING = 1;
1192	AnyEvent->one_event while !$_[0]{_ae_sent};	1528	AnyEvent->one_event while !$_[0]{_ae_sent};
1193	}	1529	}
1194		1530
1195	sub recv {	1531	sub recv {
1196	$_[0]->_wait;	1532	$_[0]->_wait;
…		…
1237	so on.	1573	so on.
1238		1574
1239	=head1 ENVIRONMENT VARIABLES	1575	=head1 ENVIRONMENT VARIABLES
1240		1576
1241	The following environment variables are used by this module or its	1577	The following environment variables are used by this module or its
1242	submodules:	1578	submodules.
		1579
		1580	Note that AnyEvent will remove I<all> environment variables starting with
		1581	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1582	enabled.
1243		1583
1244	=over 4	1584	=over 4
1245		1585
1246	=item C<PERL_ANYEVENT_VERBOSE>	1586	=item C<PERL_ANYEVENT_VERBOSE>
1247		1587
…		…
1254	C<PERL_ANYEVENT_MODEL>.	1594	C<PERL_ANYEVENT_MODEL>.
1255		1595
1256	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1596	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1257	model it chooses.	1597	model it chooses.
1258		1598
		1599	When set to C<8> or higher, then AnyEvent will report extra information on
		1600	which optional modules it loads and how it implements certain features.
		1601
1259	=item C<PERL_ANYEVENT_STRICT>	1602	=item C<PERL_ANYEVENT_STRICT>
1260		1603
1261	AnyEvent does not do much argument checking by default, as thorough	1604	AnyEvent does not do much argument checking by default, as thorough
1262	argument checking is very costly. Setting this variable to a true value	1605	argument checking is very costly. Setting this variable to a true value
1263	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1606	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1264	check the arguments passed to most method calls. If it finds any problems	1607	check the arguments passed to most method calls. If it finds any problems,
1265	it will croak.	1608	it will croak.
1266		1609
1267	In other words, enables "strict" mode.	1610	In other words, enables "strict" mode.
1268		1611
1269	Unlike C<use strict>, it is definitely recommended ot keep it off in	1612	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
1270	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1613	>>, it is definitely recommended to keep it off in production. Keeping
1271	developing programs can be very useful, however.	1614	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1615	can be very useful, however.
1272		1616
1273	=item C<PERL_ANYEVENT_MODEL>	1617	=item C<PERL_ANYEVENT_MODEL>
1274		1618
1275	This can be used to specify the event model to be used by AnyEvent, before	1619	This can be used to specify the event model to be used by AnyEvent, before
1276	auto detection and -probing kicks in. It must be a string consisting	1620	auto detection and -probing kicks in. It must be a string consisting
…		…
1319		1663
1320	=item C<PERL_ANYEVENT_MAX_FORKS>	1664	=item C<PERL_ANYEVENT_MAX_FORKS>
1321		1665
1322	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1666	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1323	will create in parallel.	1667	will create in parallel.
		1668
		1669	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1670
		1671	The default value for the C<max_outstanding> parameter for the default DNS
		1672	resolver - this is the maximum number of parallel DNS requests that are
		1673	sent to the DNS server.
		1674
		1675	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1676
		1677	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1678	configuration) in the default resolver. When set to the empty string, no
		1679	default config will be used.
		1680
		1681	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1682
		1683	When neither C<ca_file> nor C<ca_path> was specified during
		1684	L<AnyEvent::TLS> context creation, and either of these environment
		1685	variables exist, they will be used to specify CA certificate locations
		1686	instead of a system-dependent default.
		1687
		1688	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1689
		1690	When these are set to C<1>, then the respective modules are not
		1691	loaded. Mostly good for testing AnyEvent itself.
1324		1692
1325	=back	1693	=back
1326		1694
1327	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1695	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1328		1696
…		…
1573	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	1941	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1574	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	1942	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1575	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	1943	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1576	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	1944	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1577	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	1945	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1946	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1947	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1578	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	1948	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1579	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	1949	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1580	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	1950	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1581	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	1951	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1582		1952
…		…
1611	performance becomes really bad with lots of file descriptors (and few of	1981	performance becomes really bad with lots of file descriptors (and few of
1612	them active), of course, but this was not subject of this benchmark.	1982	them active), of course, but this was not subject of this benchmark.
1613		1983
1614	The C<Event> module has a relatively high setup and callback invocation	1984	The C<Event> module has a relatively high setup and callback invocation
1615	cost, but overall scores in on the third place.	1985	cost, but overall scores in on the third place.
		1986
		1987	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1988	when using its pure perl backend.
1616		1989
1617	C<Glib>'s memory usage is quite a bit higher, but it features a	1990	C<Glib>'s memory usage is quite a bit higher, but it features a
1618	faster callback invocation and overall ends up in the same class as	1991	faster callback invocation and overall ends up in the same class as
1619	C<Event>. However, Glib scales extremely badly, doubling the number of	1992	C<Event>. However, Glib scales extremely badly, doubling the number of
1620	watchers increases the processing time by more than a factor of four,	1993	watchers increases the processing time by more than a factor of four,
…		…
1698	it to another server. This includes deleting the old timeout and creating	2071	it to another server. This includes deleting the old timeout and creating
1699	a new one that moves the timeout into the future.	2072	a new one that moves the timeout into the future.
1700		2073
1701	=head3 Results	2074	=head3 Results
1702		2075
1703	name sockets create request	2076	name sockets create request
1704	EV 20000 69.01 11.16	2077	EV 20000 69.01 11.16
1705	Perl 20000 73.32 35.87	2078	Perl 20000 73.32 35.87
		2079	IOAsync 20000 157.00 98.14 epoll
		2080	IOAsync 20000 159.31 616.06 poll
1706	Event 20000 212.62 257.32	2081	Event 20000 212.62 257.32
1707	Glib 20000 651.16 1896.30	2082	Glib 20000 651.16 1896.30
1708	POE 20000 349.67 12317.24 uses POE::Loop::Event	2083	POE 20000 349.67 12317.24 uses POE::Loop::Event
1709		2084
1710	=head3 Discussion	2085	=head3 Discussion
1711		2086
1712	This benchmark I<does> measure scalability and overall performance of the	2087	This benchmark I<does> measure scalability and overall performance of the
1713	particular event loop.	2088	particular event loop.
…		…
1715	EV is again fastest. Since it is using epoll on my system, the setup time	2090	EV is again fastest. Since it is using epoll on my system, the setup time
1716	is relatively high, though.	2091	is relatively high, though.
1717		2092
1718	Perl surprisingly comes second. It is much faster than the C-based event	2093	Perl surprisingly comes second. It is much faster than the C-based event
1719	loops Event and Glib.	2094	loops Event and Glib.
		2095
		2096	IO::Async performs very well when using its epoll backend, and still quite
		2097	good compared to Glib when using its pure perl backend.
1720		2098
1721	Event suffers from high setup time as well (look at its code and you will	2099	Event suffers from high setup time as well (look at its code and you will
1722	understand why). Callback invocation also has a high overhead compared to	2100	understand why). Callback invocation also has a high overhead compared to
1723	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2101	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1724	uses select or poll in basically all documented configurations.	2102	uses select or poll in basically all documented configurations.
…		…
1787	=item * C-based event loops perform very well with small number of	2165	=item * C-based event loops perform very well with small number of
1788	watchers, as the management overhead dominates.	2166	watchers, as the management overhead dominates.
1789		2167
1790	=back	2168	=back
1791		2169
		2170	=head2 THE IO::Lambda BENCHMARK
		2171
		2172	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2173	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2174	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2175	shouldn't come as a surprise to anybody). As such, the benchmark is
		2176	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2177	very optimal. But how would AnyEvent compare when used without the extra
		2178	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2179
		2180	The benchmark itself creates an echo-server, and then, for 500 times,
		2181	connects to the echo server, sends a line, waits for the reply, and then
		2182	creates the next connection. This is a rather bad benchmark, as it doesn't
		2183	test the efficiency of the framework or much non-blocking I/O, but it is a
		2184	benchmark nevertheless.
		2185
		2186	name runtime
		2187	Lambda/select 0.330 sec
		2188	+ optimized 0.122 sec
		2189	Lambda/AnyEvent 0.327 sec
		2190	+ optimized 0.138 sec
		2191	Raw sockets/select 0.077 sec
		2192	POE/select, components 0.662 sec
		2193	POE/select, raw sockets 0.226 sec
		2194	POE/select, optimized 0.404 sec
		2195
		2196	AnyEvent/select/nb 0.085 sec
		2197	AnyEvent/EV/nb 0.068 sec
		2198	+state machine 0.134 sec
		2199
		2200	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2201	benchmarks actually make blocking connects and use 100% blocking I/O,
		2202	defeating the purpose of an event-based solution. All of the newly
		2203	written AnyEvent benchmarks use 100% non-blocking connects (using
		2204	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2205	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2206	generally require a lot more bookkeeping and event handling than blocking
		2207	connects (which involve a single syscall only).
		2208
		2209	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2210	offers similar expressive power as POE and IO::Lambda, using conventional
		2211	Perl syntax. This means that both the echo server and the client are 100%
		2212	non-blocking, further placing it at a disadvantage.
		2213
		2214	As you can see, the AnyEvent + EV combination even beats the
		2215	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2216	backend easily beats IO::Lambda and POE.
		2217
		2218	And even the 100% non-blocking version written using the high-level (and
		2219	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2220	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2221	in a non-blocking way.
		2222
		2223	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2224	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2225	part of the IO::lambda distribution and were used without any changes.
		2226
1792		2227
1793	=head1 SIGNALS	2228	=head1 SIGNALS
1794		2229
1795	AnyEvent currently installs handlers for these signals:	2230	AnyEvent currently installs handlers for these signals:
1796		2231
…		…
1799	=item SIGCHLD	2234	=item SIGCHLD
1800		2235
1801	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2236	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1802	emulation for event loops that do not support them natively. Also, some	2237	emulation for event loops that do not support them natively. Also, some
1803	event loops install a similar handler.	2238	event loops install a similar handler.
		2239
		2240	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2241	AnyEvent will reset it to default, to avoid losing child exit statuses.
1804		2242
1805	=item SIGPIPE	2243	=item SIGPIPE
1806		2244
1807	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2245	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1808	when AnyEvent gets loaded.	2246	when AnyEvent gets loaded.
…		…
1820		2258
1821	=back	2259	=back
1822		2260
1823	=cut	2261	=cut
1824		2262
		2263	undef $SIG{CHLD}
		2264	if $SIG{CHLD} eq 'IGNORE';
		2265
1825	$SIG{PIPE} = sub { }	2266	$SIG{PIPE} = sub { }
1826	unless defined $SIG{PIPE};	2267	unless defined $SIG{PIPE};
		2268
		2269	=head1 RECOMMENDED/OPTIONAL MODULES
		2270
		2271	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2272	it's built-in modules) are required to use it.
		2273
		2274	That does not mean that AnyEvent won't take advantage of some additional
		2275	modules if they are installed.
		2276
		2277	This section epxlains which additional modules will be used, and how they
		2278	affect AnyEvent's operetion.
		2279
		2280	=over 4
		2281
		2282	=item L<Async::Interrupt>
		2283
		2284	This slightly arcane module is used to implement fast signal handling: To
		2285	my knowledge, there is no way to do completely race-free and quick
		2286	signal handling in pure perl. To ensure that signals still get
		2287	delivered, AnyEvent will start an interval timer to wake up perl (and
		2288	catch the signals) with some delay (default is 10 seconds, look for
		2289	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2290
		2291	If this module is available, then it will be used to implement signal
		2292	catching, which means that signals will not be delayed, and the event loop
		2293	will not be interrupted regularly, which is more efficient (And good for
		2294	battery life on laptops).
		2295
		2296	This affects not just the pure-perl event loop, but also other event loops
		2297	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2298
		2299	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2300	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2301	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2302	does nothing for those backends.
		2303
		2304	=item L<EV>
		2305
		2306	This module isn't really "optional", as it is simply one of the backend
		2307	event loops that AnyEvent can use. However, it is simply the best event
		2308	loop available in terms of features, speed and stability: It supports
		2309	the AnyEvent API optimally, implements all the watcher types in XS, does
		2310	automatic timer adjustments even when no monotonic clock is available,
		2311	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2312	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2313	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2314
		2315	=item L<Guard>
		2316
		2317	The guard module, when used, will be used to implement
		2318	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2319	lot less memory), but otherwise doesn't affect guard operation much. It is
		2320	purely used for performance.
		2321
		2322	=item L<JSON> and L<JSON::XS>
		2323
		2324	This module is required when you want to read or write JSON data via
		2325	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2326	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2327
		2328	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2329	installed.
		2330
		2331	=item L<Net::SSLeay>
		2332
		2333	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2334	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2335	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2336
		2337	=item L<Time::HiRes>
		2338
		2339	This module is part of perl since release 5.008. It will be used when the
		2340	chosen event library does not come with a timing source on it's own. The
		2341	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2342	try to use a monotonic clock for timing stability.
		2343
		2344	=back
1827		2345
1828		2346
1829	=head1 FORK	2347	=head1 FORK
1830		2348
1831	Most event libraries are not fork-safe. The ones who are usually are	2349	Most event libraries are not fork-safe. The ones who are usually are
1832	because they rely on inefficient but fork-safe C<select> or C<poll>	2350	because they rely on inefficient but fork-safe C<select> or C<poll>
1833	calls. Only L<EV> is fully fork-aware.	2351	calls. Only L<EV> is fully fork-aware.
1834		2352
1835	If you have to fork, you must either do so I<before> creating your first	2353	If you have to fork, you must either do so I<before> creating your first
1836	watcher OR you must not use AnyEvent at all in the child.	2354	watcher OR you must not use AnyEvent at all in the child OR you must do
		2355	something completely out of the scope of AnyEvent.
1837		2356
1838		2357
1839	=head1 SECURITY CONSIDERATIONS	2358	=head1 SECURITY CONSIDERATIONS
1840		2359
1841	AnyEvent can be forced to load any event model via	2360	AnyEvent can be forced to load any event model via
…		…
1853	use AnyEvent;	2372	use AnyEvent;
1854		2373
1855	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2374	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1856	be used to probe what backend is used and gain other information (which is	2375	be used to probe what backend is used and gain other information (which is
1857	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2376	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1858	$ENV{PERL_ANYEGENT_STRICT}.	2377	$ENV{PERL_ANYEVENT_STRICT}.
		2378
		2379	Note that AnyEvent will remove I<all> environment variables starting with
		2380	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2381	enabled.
1859		2382
1860		2383
1861	=head1 BUGS	2384	=head1 BUGS
1862		2385
1863	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2386	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
…		…
1875	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2398	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1876		2399
1877	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2400	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1878	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2401	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1879	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2402	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1880	L<AnyEvent::Impl::POE>.	2403	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1881		2404
1882	Non-blocking file handles, sockets, TCP clients and	2405	Non-blocking file handles, sockets, TCP clients and
1883	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2406	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1884		2407
1885	Asynchronous DNS: L<AnyEvent::DNS>.	2408	Asynchronous DNS: L<AnyEvent::DNS>.
1886		2409
1887	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2410	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2411	L<Coro::Event>,
1888		2412
1889	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2413	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2414	L<AnyEvent::HTTP>.
1890		2415
1891		2416
1892	=head1 AUTHOR	2417	=head1 AUTHOR
1893		2418
1894	Marc Lehmann <schmorp@schmorp.de>	2419	Marc Lehmann <schmorp@schmorp.de>

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