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Revision 1.185 by root, Thu Oct 2 15:11:01 2008 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 $condvar gets ->send
29	# use a condvar in callback mode:	37	# use a condvar in callback mode:
…		…
32	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
33		41
34	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
35	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
36	L<AnyEvent::Intro> manpage.	44	L<AnyEvent::Intro> manpage.
		45
		46	=head1 SUPPORT
		47
		48	There is a mailinglist for discussing all things AnyEvent, and an IRC
		49	channel, too.
		50
		51	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		52	Respository>, at L<http://anyevent.schmorp.de>, for more info.
37		53
38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
39		55
40	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
41	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
…		…
137	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
138	creating a watcher it will immediately "watch" for events and invoke the	154	creating a watcher it will immediately "watch" for events and invoke the
139	callback when the event occurs (of course, only when the event model	155	callback when the event occurs (of course, only when the event model
140	is in control).	156	is in control).
141		157
		158	Note that B<callbacks must not permanently change global variables>
		159	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		160	callbacks must not C<die> >>. The former is good programming practise in
		161	Perl and the latter stems from the fact that exception handling differs
		162	widely between event loops.
		163
142	To disable the watcher you have to destroy it (e.g. by setting the	164	To disable the watcher you have to destroy it (e.g. by setting the
143	variable you store it in to C<undef> or otherwise deleting all references	165	variable you store it in to C<undef> or otherwise deleting all references
144	to it).	166	to it).
145		167
146	All watchers are created by calling a method on the C<AnyEvent> class.	168	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
162	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
163		185
164	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
165	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
166		188
167	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
168	(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
169	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
170	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
171	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.
172		200
173	Although the callback might get passed parameters, their value and	201	Although the callback might get passed parameters, their value and
174	presence is undefined and you cannot rely on them. Portable AnyEvent	202	presence is undefined and you cannot rely on them. Portable AnyEvent
175	callbacks cannot use arguments passed to I/O watcher callbacks.	203	callbacks cannot use arguments passed to I/O watcher callbacks.
176		204
…		…
308	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
309	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
310	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	338	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
311	account.	339	account.
312		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
313	=back	356	=back
314		357
315	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
316		359
317	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
…		…
326	invocation, and callback invocation will be synchronous. Synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
327	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,
328	but it is guaranteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
329		372
330	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
331	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
332		376
333	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
334	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
335		380
336	Example: exit on SIGINT	381	Example: exit on SIGINT
337		382
338	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.
339		400
340	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
341		402
342	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.
343		404
…		…
357		418
358	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
359	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
360	have exited already (and no SIGCHLD will be sent anymore).	421	have exited already (and no SIGCHLD will be sent anymore).
361		422
362	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
363	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
364	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.
365		429
366	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
367	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
368	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.
369		438
370	Example: fork a process and wait for it	439	Example: fork a process and wait for it
371		440
372	my $done = AnyEvent->condvar;	441	my $done = AnyEvent->condvar;
373		442
…		…
383	);	452	);
384		453
385	# do something else, then wait for process exit	454	# do something else, then wait for process exit
386	$done->recv;	455	$done->recv;
387		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
388	=head2 CONDITION VARIABLES	492	=head2 CONDITION VARIABLES
389		493
390	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
391	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
392	will actively watch for new events and call your callbacks.	496	will actively watch for new events and call your callbacks.
393		497
394	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
395	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).
396		500
397	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
398	because they represent a condition that must become true.	502	because they represent a condition that must become true.
399		503
		504	Now is probably a good time to look at the examples further below.
		505
400	Condition variables can be created by calling the C<< AnyEvent->condvar	506	Condition variables can be created by calling the C<< AnyEvent->condvar
401	>> method, usually without arguments. The only argument pair allowed is	507	>> method, usually without arguments. The only argument pair allowed is
402
403	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
404	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
405	the results).	510	the results).
406		511
407	After creation, the condition variable is "false" until it becomes "true"	512	After creation, the condition variable is "false" until it becomes "true"
…		…
456	after => 1,	561	after => 1,
457	cb => sub { $result_ready->send },	562	cb => sub { $result_ready->send },
458	);	563	);
459		564
460	# this "blocks" (while handling events) till the callback	565	# this "blocks" (while handling events) till the callback
461	# calls send	566	# calls -<send
462	$result_ready->recv;	567	$result_ready->recv;
463		568
464	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
465	condition variables are also code references.	570	variables are also callable directly.
466		571
467	my $done = AnyEvent->condvar;	572	my $done = AnyEvent->condvar;
468	my $delay = AnyEvent->timer (after => 5, cb => $done);	573	my $delay = AnyEvent->timer (after => 5, cb => $done);
469	$done->recv;	574	$done->recv;
470		575
…		…
476		581
477	...	582	...
478		583
479	my @info = $couchdb->info->recv;	584	my @info = $couchdb->info->recv;
480		585
481	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
482	results are available:	587	results are available:
483		588
484	$couchdb->info->cb (sub {	589	$couchdb->info->cb (sub {
485	my @info = $_[0]->recv;	590	my @info = $_[0]->recv;
486	});	591	});
…		…
504	immediately from within send.	609	immediately from within send.
505		610
506	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
507	future C<< ->recv >> calls.	612	future C<< ->recv >> calls.
508		613
509	Condition variables are overloaded so one can call them directly	614	Condition variables are overloaded so one can call them directly (as if
510	(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
511	C<send>. Note, however, that many C-based event loops do not handle	616	C<send>.
512	overloading, so as tempting as it may be, passing a condition variable
513	instead of a callback does not work. Both the pure perl and EV loops
514	support overloading, however, as well as all functions that use perl to
515	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
516	example).
517		617
518	=item $cv->croak ($error)	618	=item $cv->croak ($error)
519		619
520	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
521	C<Carp::croak> with the given error message/object/scalar.	621	C<Carp::croak> with the given error message/object/scalar.
522		622
523	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
524	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.
525		629
526	=item $cv->begin ([group callback])	630	=item $cv->begin ([group callback])
527		631
528	=item $cv->end	632	=item $cv->end
529
530	These two methods are EXPERIMENTAL and MIGHT CHANGE.
531		633
532	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
533	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
534	to use a condition variable for the whole process.	636	to use a condition variable for the whole process.
535		637
…		…
537	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
538	>>, 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
539	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
540	callback was set, C<send> will be called without any arguments.	642	callback was set, C<send> will be called without any arguments.
541		643
542	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:
543		675
544	my $cv = AnyEvent->condvar;	676	my $cv = AnyEvent->condvar;
545		677
546	my %result;	678	my %result;
547	$cv->begin (sub { $cv->send (\%result) });	679	$cv->begin (sub { $cv->send (\%result) });
…		…
567	loop, which serves two important purposes: first, it sets the callback	699	loop, which serves two important purposes: first, it sets the callback
568	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
569	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
570	doesn't execute once).	702	doesn't execute once).
571		703
572	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
573	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
574	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
575	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>.
576		709
577	=back	710	=back
578		711
579	=head3 METHODS FOR CONSUMERS	712	=head3 METHODS FOR CONSUMERS
580		713
…		…
596	function will call C<croak>.	729	function will call C<croak>.
597		730
598	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,
599	in scalar context only the first one will be returned.	732	in scalar context only the first one will be returned.
600		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
601	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
602	(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
603	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
604	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
605	condition variables with some kind of request results and supporting	745	condition variables with some kind of request results and supporting
606	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,
607	while still supporting blocking waits if the caller so desires).	747	while still supporting blocking waits if the caller so desires).
608		748
609	Another reason I<never> to C<< ->recv >> in a module is that you cannot
610	sensibly have two C<< ->recv >>'s in parallel, as that would require
611	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
612	can supply.
613
614	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
615	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
616	versions and also integrates coroutines into AnyEvent, making blocking
617	C<< ->recv >> calls perfectly safe as long as they are done from another
618	coroutine (one that doesn't run the event loop).
619
620	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
621	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
622	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
623	waits otherwise.	752	waits otherwise.
624		753
…		…
637	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
638	is guaranteed not to block.	767	is guaranteed not to block.
639		768
640	=back	769	=back
641		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
642	=head1 GLOBAL VARIABLES AND FUNCTIONS	838	=head1 GLOBAL VARIABLES AND FUNCTIONS
643		839
		840	These are not normally required to use AnyEvent, but can be useful to
		841	write AnyEvent extension modules.
		842
644	=over 4	843	=over 4
645		844
646	=item $AnyEvent::MODEL	845	=item $AnyEvent::MODEL
647		846
648	Contains C<undef> until the first watcher is being created. Then it	847	Contains C<undef> until the first watcher is being created, before the
		848	backend has been autodetected.
		849
649	contains the event model that is being used, which is the name of the	850	Afterwards it contains the event model that is being used, which is the
650	Perl class implementing the model. This class is usually one of the	851	name of the Perl class implementing the model. This class is usually one
651	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	852	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
652	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	853	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
653		854	will be C<urxvt::anyevent>).
654	The known classes so far are:
655
656	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
657	AnyEvent::Impl::Event based on Event, second best choice.
658	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
659	AnyEvent::Impl::Glib based on Glib, third-best choice.
660	AnyEvent::Impl::Tk based on Tk, very bad choice.
661	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
662	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
663	AnyEvent::Impl::POE based on POE, not generic enough for full support.
664
665	There is no support for WxWidgets, as WxWidgets has no support for
666	watching file handles. However, you can use WxWidgets through the
667	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
668	second, which was considered to be too horrible to even consider for
669	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
670	it's adaptor.
671
672	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
673	autodetecting them.
674		855
675	=item AnyEvent::detect	856	=item AnyEvent::detect
676		857
677	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	858	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
678	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
679	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
680	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>.
681		865
682	=item $guard = AnyEvent::post_detect { BLOCK }	866	=item $guard = AnyEvent::post_detect { BLOCK }
683		867
684	Arranges for the code block to be executed as soon as the event model is	868	Arranges for the code block to be executed as soon as the event model is
685	autodetected (or immediately if this has already happened).	869	autodetected (or immediately if this has already happened).
		870
		871	The block will be executed I<after> the actual backend has been detected
		872	(C<$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.
686		881
687	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
688	that automatically removes the callback again when it is destroyed. See	883	that automatically removes the callback again when it is destroyed. See
689	L<Coro::BDB> for a case where this is useful.	884	L<Coro::BDB> for a case where this is useful.
690		885
…		…
693	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
694	before or after loading AnyEvent), then they will called directly after	889	before or after loading AnyEvent), then they will called directly after
695	the event loop has been chosen.	890	the event loop has been chosen.
696		891
697	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:
698	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
699	and the array will be ignored.	894	array will be ignored.
700		895
701	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.
702		903
703	=back	904	=back
704		905
705	=head1 WHAT TO DO IN A MODULE	906	=head1 WHAT TO DO IN A MODULE
706		907
…		…
761		962
762		963
763	=head1 OTHER MODULES	964	=head1 OTHER MODULES
764		965
765	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
766	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
767	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
768	available via CPAN.	969	come with AnyEvent, most are available via CPAN.
769		970
770	=over 4	971	=over 4
771		972
772	=item L<AnyEvent::Util>	973	=item L<AnyEvent::Util>
773		974
…		…
782		983
783	=item L<AnyEvent::Handle>	984	=item L<AnyEvent::Handle>
784		985
785	Provide read and write buffers, manages watchers for reads and writes,	986	Provide read and write buffers, manages watchers for reads and writes,
786	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
787	non-blocking SSL/TLS.	988	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
788		989
789	=item L<AnyEvent::DNS>	990	=item L<AnyEvent::DNS>
790		991
791	Provides rich asynchronous DNS resolver capabilities.	992	Provides rich asynchronous DNS resolver capabilities.
792		993
…		…
820		1021
821	=item L<AnyEvent::GPSD>	1022	=item L<AnyEvent::GPSD>
822		1023
823	A non-blocking interface to gpsd, a daemon delivering GPS information.	1024	A non-blocking interface to gpsd, a daemon delivering GPS information.
824		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
825	=item L<AnyEvent::IGS>	1035	=item L<AnyEvent::IGS>
826		1036
827	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
828	L<App::IGS>).	1038	L<App::IGS>).
829		1039
830	=item L<AnyEvent::IRC>
831
832	AnyEvent based IRC client module family (replacing the older Net::IRC3).
833
834	=item L<Net::XMPP2>
835
836	AnyEvent based XMPP (Jabber protocol) module family.
837
838	=item L<Net::FCP>	1040	=item L<Net::FCP>
839		1041
840	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1042	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
841	of AnyEvent.	1043	of AnyEvent.
842		1044
…		…
846		1048
847	=item L<Coro>	1049	=item L<Coro>
848		1050
849	Has special support for AnyEvent via L<Coro::AnyEvent>.	1051	Has special support for AnyEvent via L<Coro::AnyEvent>.
850		1052
851	=item L<IO::Lambda>
852
853	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
854
855	=back	1053	=back
856		1054
857	=cut	1055	=cut
858		1056
859	package AnyEvent;	1057	package AnyEvent;
860		1058
		1059	# basically a tuned-down version of common::sense
		1060	sub common_sense {
861	no warnings;	1061	# no warnings
		1062	${^WARNING_BITS} ^= ${^WARNING_BITS};
862	use strict qw(vars subs);	1063	# use strict vars subs
		1064	$^H |= 0x00000600;
		1065	}
863		1066
		1067	BEGIN { AnyEvent::common_sense }
		1068
864	use Carp;	1069	use Carp ();
865		1070
866	our $VERSION = 4.3;	1071	our $VERSION = 4.85;
867	our $MODEL;	1072	our $MODEL;
868		1073
869	our $AUTOLOAD;	1074	our $AUTOLOAD;
870	our @ISA;	1075	our @ISA;
871		1076
872	our @REGISTRY;	1077	our @REGISTRY;
873		1078
874	our $WIN32;	1079	our $WIN32;
875		1080
		1081	our $VERBOSE;
		1082
876	BEGIN {	1083	BEGIN {
877	my $win32 = ! ! ($^O =~ /mswin32/i);	1084	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
878	eval "sub WIN32(){ $win32 }";	1085	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
879	}
880		1086
		1087	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1088	if ${^TAINT};
		1089
881	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1090	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1091
		1092	}
		1093
		1094	our $MAX_SIGNAL_LATENCY = 10;
882		1095
883	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1096	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
884		1097
885	{	1098	{
886	my $idx;	1099	my $idx;
…		…
894	[Event:: => AnyEvent::Impl::Event::],	1107	[Event:: => AnyEvent::Impl::Event::],
895	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1108	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
896	# everything below here will not be autoprobed	1109	# everything below here will not be autoprobed
897	# as the pureperl backend should work everywhere	1110	# as the pureperl backend should work everywhere
898	# and is usually faster	1111	# and is usually faster
899	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
900	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1112	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
901	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1113	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1114	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
902	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1115	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
903	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1116	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
904	[Wx:: => AnyEvent::Impl::POE::],	1117	[Wx:: => AnyEvent::Impl::POE::],
905	[Prima:: => AnyEvent::Impl::POE::],	1118	[Prima:: => AnyEvent::Impl::POE::],
		1119	# IO::Async is just too broken - we would need workarounds for its
		1120	# byzantine signal and broken child handling, among others.
		1121	# IO::Async is rather hard to detect, as it doesn't have any
		1122	# obvious default class.
		1123	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1124	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1125	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
906	);	1126	);
907		1127
908	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1128	our %method = map +($_ => 1),
		1129	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
909		1130
910	our @post_detect;	1131	our @post_detect;
911		1132
912	sub post_detect(&) {	1133	sub post_detect(&) {
913	my ($cb) = @_;	1134	my ($cb) = @_;
…		…
918	1	1139	1
919	} else {	1140	} else {
920	push @post_detect, $cb;	1141	push @post_detect, $cb;
921		1142
922	defined wantarray	1143	defined wantarray
923	? bless \$cb, "AnyEvent::Util::PostDetect"	1144	? bless \$cb, "AnyEvent::Util::postdetect"
924	: ()	1145	: ()
925	}	1146	}
926	}	1147	}
927		1148
928	sub AnyEvent::Util::PostDetect::DESTROY {	1149	sub AnyEvent::Util::postdetect::DESTROY {
929	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1150	@post_detect = grep $_ != ${$_[0]}, @post_detect;
930	}	1151	}
931		1152
932	sub detect() {	1153	sub detect() {
933	unless ($MODEL) {	1154	unless ($MODEL) {
934	no strict 'refs';
935	local $SIG{__DIE__};	1155	local $SIG{__DIE__};
936		1156
937	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1157	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
938	my $model = "AnyEvent::Impl::$1";	1158	my $model = "AnyEvent::Impl::$1";
939	if (eval "require $model") {	1159	if (eval "require $model") {
940	$MODEL = $model;	1160	$MODEL = $model;
941	warn "AnyEvent: loaded model '$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 $VERBOSE >= 2;
942	} else {	1162	} else {
943	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1163	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
944	}	1164	}
945	}	1165	}
946		1166
947	# check for already loaded models	1167	# check for already loaded models
948	unless ($MODEL) {	1168	unless ($MODEL) {
949	for (@REGISTRY, @models) {	1169	for (@REGISTRY, @models) {
950	my ($package, $model) = @$_;	1170	my ($package, $model) = @$_;
951	if (${"$package\::VERSION"} > 0) {	1171	if (${"$package\::VERSION"} > 0) {
952	if (eval "require $model") {	1172	if (eval "require $model") {
953	$MODEL = $model;	1173	$MODEL = $model;
954	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1174	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
955	last;	1175	last;
956	}	1176	}
957	}	1177	}
958	}	1178	}
959		1179
…		…
964	my ($package, $model) = @$_;	1184	my ($package, $model) = @$_;
965	if (eval "require $package"	1185	if (eval "require $package"
966	and ${"$package\::VERSION"} > 0	1186	and ${"$package\::VERSION"} > 0
967	and eval "require $model") {	1187	and eval "require $model") {
968	$MODEL = $model;	1188	$MODEL = $model;
969	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1189	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
970	last;	1190	last;
971	}	1191	}
972	}	1192	}
973		1193
974	$MODEL	1194	$MODEL
975	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1195	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
976	}	1196	}
977	}	1197	}
978		1198
979	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1199	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
980		1200
…		…
990		1210
991	sub AUTOLOAD {	1211	sub AUTOLOAD {
992	(my $func = $AUTOLOAD) =~ s/.*://;	1212	(my $func = $AUTOLOAD) =~ s/.*://;
993		1213
994	$method{$func}	1214	$method{$func}
995	or croak "$func: not a valid method for AnyEvent objects";	1215	or Carp::croak "$func: not a valid method for AnyEvent objects";
996		1216
997	detect unless $MODEL;	1217	detect unless $MODEL;
998		1218
999	my $class = shift;	1219	my $class = shift;
1000	$class->$func (@_);	1220	$class->$func (@_);
1001	}	1221	}
1002		1222
1003	# 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
1004	# to support binding more than one watcher per filehandle (they usually	1224	# to support binding more than one watcher per filehandle (they usually
1005	# 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).
1006	sub _dupfh($$$$) {	1226	sub _dupfh($$;$$) {
1007	my ($poll, $fh, $r, $w) = @_;	1227	my ($poll, $fh, $r, $w) = @_;
1008		1228
1009	require Fcntl;
1010
1011	# cygwin requires the fh mode to be matching, unix doesn't	1229	# cygwin requires the fh mode to be matching, unix doesn't
1012	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1230	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1013	: $poll eq "w" ? ($w, ">")
1014	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1015		1231
1016	open my $fh2, "$mode&" . fileno $fh	1232	open my $fh2, $mode, $fh
1017	or die "cannot dup() filehandle: $!";	1233	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1018		1234
1019	# 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
1020		1236
1021	($fh2, $rw)	1237	($fh2, $rw)
1022	}	1238	}
1023		1239
1024	package AnyEvent::Base;	1240	package AnyEvent::Base;
1025		1241
1026	# default implementation for now and time	1242	# default implementations for many methods
1027		1243
1028	BEGIN {	1244	sub _time {
		1245	# probe for availability of Time::HiRes
1029	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;
1030	*_time = \&Time::HiRes::time;	1248	*_time = \&Time::HiRes::time;
1031	# if (eval "use POSIX (); (POSIX::times())...	1249	# if (eval "use POSIX (); (POSIX::times())...
1032	} else {	1250	} else {
		1251	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1033	*_time = sub { time }; # epic fail	1252	*_time = sub { time }; # epic fail
1034	}	1253	}
		1254
		1255	&_time
1035	}	1256	}
1036		1257
1037	sub time { _time }	1258	sub time { _time }
1038	sub now { _time }	1259	sub now { _time }
		1260	sub now_update { }
1039		1261
1040	# default implementation for ->condvar	1262	# default implementation for ->condvar
1041		1263
1042	sub condvar {	1264	sub condvar {
1043	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1265	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1044	}	1266	}
1045		1267
1046	# default implementation for ->signal	1268	# default implementation for ->signal
1047		1269
1048	our %SIG_CB;	1270	our $HAVE_ASYNC_INTERRUPT;
		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);
1049		1274
		1275	sub _signal_exec {
		1276	$HAVE_ASYNC_INTERRUPT
		1277	? $SIGPIPE_R->drain
		1278	: sysread $SIGPIPE_R, my $dummy, 9;
		1279
		1280	while (%SIG_EV) {
		1281	for (keys %SIG_EV) {
		1282	delete $SIG_EV{$_};
		1283	$_->() for values %{ $SIG_CB{$_} || {} };
		1284	}
		1285	}
		1286	}
		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
1050	sub signal {	1307	sub _signal {
1051	my (undef, %arg) = @_;	1308	my (undef, %arg) = @_;
1052		1309
1053	my $signal = uc $arg{signal}	1310	my $signal = uc $arg{signal}
1054	or Carp::croak "required option 'signal' is missing";	1311	or Carp::croak "required option 'signal' is missing";
1055		1312
1056	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	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
1057	$SIG{$signal} ||= sub {	1332	$SIG{$signal} ||= sub {
1058	$_->() for values %{ $SIG_CB{$signal} || {} };	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;
1059	};	1341	}
1060		1342
1061	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1343	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1062	}	1344	}
1063		1345
		1346	sub signal {
		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;
		1350
		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
		1360	if (AnyEvent::WIN32) {
		1361	require AnyEvent::Util;
		1362
		1363	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1364	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1365	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1366	} else {
		1367	pipe $SIGPIPE_R, $SIGPIPE_W;
		1368	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		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;
		1374	}
		1375
		1376	$SIGPIPE_R
		1377	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1378
		1379	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1380	}
		1381
		1382	*signal = \&_signal;
		1383	&signal
		1384	}
		1385
1064	sub AnyEvent::Base::Signal::DESTROY {	1386	sub AnyEvent::Base::signal::DESTROY {
1065	my ($signal, $cb) = @{$_[0]};	1387	my ($signal, $cb) = @{$_[0]};
1066		1388
		1389	_sig_del;
		1390
1067	delete $SIG_CB{$signal}{$cb};	1391	delete $SIG_CB{$signal}{$cb};
1068		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}
1069	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1399	unless keys %{ $SIG_CB{$signal} };
1070	}	1400	}
1071		1401
1072	# default implementation for ->child	1402	# default implementation for ->child
1073		1403
1074	our %PID_CB;	1404	our %PID_CB;
1075	our $CHLD_W;	1405	our $CHLD_W;
1076	our $CHLD_DELAY_W;	1406	our $CHLD_DELAY_W;
1077	our $PID_IDLE;
1078	our $WNOHANG;	1407	our $WNOHANG;
1079		1408
1080	sub _child_wait {	1409	sub _sigchld {
1081	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1410	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1411	$_->($pid, $?)
1082	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1412	for values %{ $PID_CB{$pid} || {} },
1083	(values %{ $PID_CB{0} || {} });	1413	values %{ $PID_CB{0} || {} };
1084	}	1414	}
1085
1086	undef $PID_IDLE;
1087	}
1088
1089	sub _sigchld {
1090	# make sure we deliver these changes "synchronous" with the event loop.
1091	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1092	undef $CHLD_DELAY_W;
1093	&_child_wait;
1094	});
1095	}	1415	}
1096		1416
1097	sub child {	1417	sub child {
1098	my (undef, %arg) = @_;	1418	my (undef, %arg) = @_;
1099		1419
1100	defined (my $pid = $arg{pid} + 0)	1420	defined (my $pid = $arg{pid} + 0)
1101	or Carp::croak "required option 'pid' is missing";	1421	or Carp::croak "required option 'pid' is missing";
1102		1422
1103	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1423	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1104		1424
1105	unless ($WNOHANG) {	1425	# WNOHANG is almost cetrainly 1 everywhere
		1426	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1427	? 1
1106	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1428	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1107	}
1108		1429
1109	unless ($CHLD_W) {	1430	unless ($CHLD_W) {
1110	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1431	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1111	# 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
1112	&_sigchld;	1433	&_sigchld;
1113	}	1434	}
1114		1435
1115	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1436	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1116	}	1437	}
1117		1438
1118	sub AnyEvent::Base::Child::DESTROY {	1439	sub AnyEvent::Base::child::DESTROY {
1119	my ($pid, $cb) = @{$_[0]};	1440	my ($pid, $cb) = @{$_[0]};
1120		1441
1121	delete $PID_CB{$pid}{$cb};	1442	delete $PID_CB{$pid}{$cb};
1122	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1443	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1123		1444
1124	undef $CHLD_W unless keys %PID_CB;	1445	undef $CHLD_W unless keys %PID_CB;
1125	}	1446	}
1126		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
1127	package AnyEvent::CondVar;	1484	package AnyEvent::CondVar;
1128		1485
1129	our @ISA = AnyEvent::CondVar::Base::;	1486	our @ISA = AnyEvent::CondVar::Base::;
1130		1487
1131	package AnyEvent::CondVar::Base;	1488	package AnyEvent::CondVar::Base;
1132		1489
1133	use overload	1490	#use overload
1134	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1491	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1135	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;
1136		1501
1137	sub _send {	1502	sub _send {
1138	# nop	1503	# nop
1139	}	1504	}
1140		1505
…		…
1153	sub ready {	1518	sub ready {
1154	$_[0]{_ae_sent}	1519	$_[0]{_ae_sent}
1155	}	1520	}
1156		1521
1157	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 $WAITING = 1;
1158	AnyEvent->one_event while !$_[0]{_ae_sent};	1528	AnyEvent->one_event while !$_[0]{_ae_sent};
1159	}	1529	}
1160		1530
1161	sub recv {	1531	sub recv {
1162	$_[0]->_wait;	1532	$_[0]->_wait;
…		…
1203	so on.	1573	so on.
1204		1574
1205	=head1 ENVIRONMENT VARIABLES	1575	=head1 ENVIRONMENT VARIABLES
1206		1576
1207	The following environment variables are used by this module or its	1577	The following environment variables are used by this module or its
1208	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.
1209		1583
1210	=over 4	1584	=over 4
1211		1585
1212	=item C<PERL_ANYEVENT_VERBOSE>	1586	=item C<PERL_ANYEVENT_VERBOSE>
1213		1587
…		…
1220	C<PERL_ANYEVENT_MODEL>.	1594	C<PERL_ANYEVENT_MODEL>.
1221		1595
1222	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
1223	model it chooses.	1597	model it chooses.
1224		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
1225	=item C<PERL_ANYEVENT_STRICT>	1602	=item C<PERL_ANYEVENT_STRICT>
1226		1603
1227	AnyEvent does not do much argument checking by default, as thorough	1604	AnyEvent does not do much argument checking by default, as thorough
1228	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
1229	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
1230	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,
1231	it will croak.	1608	it will croak.
1232		1609
1233	In other words, enables "strict" mode.	1610	In other words, enables "strict" mode.
1234		1611
1235	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>
1236	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1613	>>, it is definitely recommended to keep it off in production. Keeping
1237	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.
1238		1616
1239	=item C<PERL_ANYEVENT_MODEL>	1617	=item C<PERL_ANYEVENT_MODEL>
1240		1618
1241	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
1242	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
…		…
1263	used, and preference will be given to protocols mentioned earlier in the	1641	used, and preference will be given to protocols mentioned earlier in the
1264	list.	1642	list.
1265		1643
1266	This variable can effectively be used for denial-of-service attacks	1644	This variable can effectively be used for denial-of-service attacks
1267	against local programs (e.g. when setuid), although the impact is likely	1645	against local programs (e.g. when setuid), although the impact is likely
1268	small, as the program has to handle connection errors already-	1646	small, as the program has to handle conenction and other failures anyways.
1269		1647
1270	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,	1648	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1271	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>	1649	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1272	- only support IPv4, never try to resolve or contact IPv6	1650	- only support IPv4, never try to resolve or contact IPv6
1273	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or	1651	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
…		…
1285		1663
1286	=item C<PERL_ANYEVENT_MAX_FORKS>	1664	=item C<PERL_ANYEVENT_MAX_FORKS>
1287		1665
1288	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>
1289	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.
1290		1692
1291	=back	1693	=back
1292		1694
1293	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1695	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1294		1696
…		…
1533	watcher.	1935	watcher.
1534		1936
1535	=head3 Results	1937	=head3 Results
1536		1938
1537	name watchers bytes create invoke destroy comment	1939	name watchers bytes create invoke destroy comment
1538	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1940	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1539	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1941	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1540	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1942	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1541	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1943	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1542	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1944	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1543	Event/Any 16000 590 35.75 31.42 1.08 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
1544	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1948	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1545	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1949	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1546	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1950	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1547	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1951	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1548		1952
1549	=head3 Discussion	1953	=head3 Discussion
1550		1954
1551	The benchmark does I<not> measure scalability of the event loop very	1955	The benchmark does I<not> measure scalability of the event loop very
1552	well. For example, a select-based event loop (such as the pure perl one)	1956	well. For example, a select-based event loop (such as the pure perl one)
…		…
1577	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
1578	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.
1579		1983
1580	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
1581	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.
1582		1989
1583	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
1584	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
1585	C<Event>. However, Glib scales extremely badly, doubling the number of	1992	C<Event>. However, Glib scales extremely badly, doubling the number of
1586	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,
…		…
1664	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
1665	a new one that moves the timeout into the future.	2072	a new one that moves the timeout into the future.
1666		2073
1667	=head3 Results	2074	=head3 Results
1668		2075
1669	name sockets create request	2076	name sockets create request
1670	EV 20000 69.01 11.16	2077	EV 20000 69.01 11.16
1671	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
1672	Event 20000 212.62 257.32	2081	Event 20000 212.62 257.32
1673	Glib 20000 651.16 1896.30	2082	Glib 20000 651.16 1896.30
1674	POE 20000 349.67 12317.24 uses POE::Loop::Event	2083	POE 20000 349.67 12317.24 uses POE::Loop::Event
1675		2084
1676	=head3 Discussion	2085	=head3 Discussion
1677		2086
1678	This benchmark I<does> measure scalability and overall performance of the	2087	This benchmark I<does> measure scalability and overall performance of the
1679	particular event loop.	2088	particular event loop.
…		…
1681	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
1682	is relatively high, though.	2091	is relatively high, though.
1683		2092
1684	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
1685	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.
1686		2098
1687	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
1688	understand why). Callback invocation also has a high overhead compared to	2100	understand why). Callback invocation also has a high overhead compared to
1689	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
1690	uses select or poll in basically all documented configurations.	2102	uses select or poll in basically all documented configurations.
…		…
1753	=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
1754	watchers, as the management overhead dominates.	2166	watchers, as the management overhead dominates.
1755		2167
1756	=back	2168	=back
1757		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
1758		2227
1759	=head1 SIGNALS	2228	=head1 SIGNALS
1760		2229
1761	AnyEvent currently installs handlers for these signals:	2230	AnyEvent currently installs handlers for these signals:
1762		2231
…		…
1765	=item SIGCHLD	2234	=item SIGCHLD
1766		2235
1767	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
1768	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
1769	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.
1770		2242
1771	=item SIGPIPE	2243	=item SIGPIPE
1772		2244
1773	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>
1774	when AnyEvent gets loaded.	2246	when AnyEvent gets loaded.
…		…
1786		2258
1787	=back	2259	=back
1788		2260
1789	=cut	2261	=cut
1790		2262
		2263	undef $SIG{CHLD}
		2264	if $SIG{CHLD} eq 'IGNORE';
		2265
1791	$SIG{PIPE} = sub { }	2266	$SIG{PIPE} = sub { }
1792	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
1793		2345
1794		2346
1795	=head1 FORK	2347	=head1 FORK
1796		2348
1797	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
1798	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>
1799	calls. Only L<EV> is fully fork-aware.	2351	calls. Only L<EV> is fully fork-aware.
1800		2352
1801	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
1802	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.
1803		2356
1804		2357
1805	=head1 SECURITY CONSIDERATIONS	2358	=head1 SECURITY CONSIDERATIONS
1806		2359
1807	AnyEvent can be forced to load any event model via	2360	AnyEvent can be forced to load any event model via
…		…
1819	use AnyEvent;	2372	use AnyEvent;
1820		2373
1821	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2374	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1822	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
1823	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
1824	$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.
1825		2382
1826		2383
1827	=head1 BUGS	2384	=head1 BUGS
1828		2385
1829	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
1830	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2387	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1831	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2388	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1832	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2389	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1833	pronounced).	2390	pronounced).
1834		2391
1835		2392
1836	=head1 SEE ALSO	2393	=head1 SEE ALSO
1837		2394
…		…
1841	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2398	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1842		2399
1843	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2400	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1844	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>,
1845	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2402	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1846	L<AnyEvent::Impl::POE>.	2403	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1847		2404
1848	Non-blocking file handles, sockets, TCP clients and	2405	Non-blocking file handles, sockets, TCP clients and
1849	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2406	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1850		2407
1851	Asynchronous DNS: L<AnyEvent::DNS>.	2408	Asynchronous DNS: L<AnyEvent::DNS>.
1852		2409
1853	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>,
1854		2412
1855	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>.
1856		2415
1857		2416
1858	=head1 AUTHOR	2417	=head1 AUTHOR
1859		2418
1860	Marc Lehmann <schmorp@schmorp.de>	2419	Marc Lehmann <schmorp@schmorp.de>

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