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Revision 1.266 by root, Thu Jul 30 03:41:56 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
…		…
39	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
40		41
41	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
42	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
43	L<AnyEvent::Intro> manpage.	44	L<AnyEvent::Intro> manpage.
		45
		46	=head1 SUPPORT
		47
		48	There is a mailinglist for discussing all things AnyEvent, and an IRC
		49	channel, too.
		50
		51	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		52	Repository>, at L<http://anyevent.schmorp.de>, for more info.
44		53
45	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
46		55
47	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
48	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
…		…
172	my variables are only visible after the statement in which they are	181	my variables are only visible after the statement in which they are
173	declared.	182	declared.
174		183
175	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
176		185
		186	$w = AnyEvent->io (
		187	fh => <filehandle_or_fileno>,
		188	poll => <"r" or "w">,
		189	cb => <callback>,
		190	);
		191
177	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	192	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
178	with the following mandatory key-value pairs as arguments:	193	with the following mandatory key-value pairs as arguments:
179		194
180	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch	195	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
181	for events (AnyEvent might or might not keep a reference to this file	196	for events (AnyEvent might or might not keep a reference to this file
182	handle). Note that only file handles pointing to things for which	197	handle). Note that only file handles pointing to things for which
183	non-blocking operation makes sense are allowed. This includes sockets,	198	non-blocking operation makes sense are allowed. This includes sockets,
184	most character devices, pipes, fifos and so on, but not for example files	199	most character devices, pipes, fifos and so on, but not for example files
185	or block devices.	200	or block devices.
…		…
210	undef $w;	225	undef $w;
211	});	226	});
212		227
213	=head2 TIME WATCHERS	228	=head2 TIME WATCHERS
214		229
		230	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		231
		232	$w = AnyEvent->timer (
		233	after => <fractional_seconds>,
		234	interval => <fractional_seconds>,
		235	cb => <callback>,
		236	);
		237
215	You can create a time watcher by calling the C<< AnyEvent->timer >>	238	You can create a time watcher by calling the C<< AnyEvent->timer >>
216	method with the following mandatory arguments:	239	method with the following mandatory arguments:
217		240
218	C<after> specifies after how many seconds (fractional values are	241	C<after> specifies after how many seconds (fractional values are
219	supported) the callback should be invoked. C<cb> is the callback to invoke	242	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
346		369
347	=back	370	=back
348		371
349	=head2 SIGNAL WATCHERS	372	=head2 SIGNAL WATCHERS
350		373
		374	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
		375
351	You can watch for signals using a signal watcher, C<signal> is the signal	376	You can watch for signals using a signal watcher, C<signal> is the signal
352	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl	377	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
353	callback to be invoked whenever a signal occurs.	378	callback to be invoked whenever a signal occurs.
354		379
355	Although the callback might get passed parameters, their value and	380	Although the callback might get passed parameters, their value and
…		…
360	invocation, and callback invocation will be synchronous. Synchronous means	385	invocation, and callback invocation will be synchronous. Synchronous means
361	that it might take a while until the signal gets handled by the process,	386	that it might take a while until the signal gets handled by the process,
362	but it is guaranteed not to interrupt any other callbacks.	387	but it is guaranteed not to interrupt any other callbacks.
363		388
364	The main advantage of using these watchers is that you can share a signal	389	The main advantage of using these watchers is that you can share a signal
365	between multiple watchers.	390	between multiple watchers, and AnyEvent will ensure that signals will not
		391	interrupt your program at bad times.
366		392
367	This watcher might use C<%SIG>, so programs overwriting those signals	393	This watcher might use C<%SIG> (depending on the event loop used),
368	directly will likely not work correctly.	394	so programs overwriting those signals directly will likely not work
		395	correctly.
369		396
370	Example: exit on SIGINT	397	Example: exit on SIGINT
371		398
372	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	399	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
373		400
		401	=head3 Signal Races, Delays and Workarounds
		402
		403	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		404	callbacks to signals in a generic way, which is a pity, as you cannot do
		405	race-free signal handling in perl. AnyEvent will try to do it's best, but
		406	in some cases, signals will be delayed. The maximum time a signal might
		407	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		408	seconds). This variable can be changed only before the first signal
		409	watcher is created, and should be left alone otherwise. Higher values
		410	will cause fewer spurious wake-ups, which is better for power and CPU
		411	saving. All these problems can be avoided by installing the optional
		412	L<Async::Interrupt> module. This will not work with inherently broken
		413	event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
		414	currently, as POE does it's own workaround with one-second latency). With
		415	those, you just have to suffer the delays.
		416
374	=head2 CHILD PROCESS WATCHERS	417	=head2 CHILD PROCESS WATCHERS
375		418
		419	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		420
376	You can also watch on a child process exit and catch its exit status.	421	You can also watch on a child process exit and catch its exit status.
377		422
378	The child process is specified by the C<pid> argument (if set to C<0>, it	423	The child process is specified by the C<pid> argument (one some backends,
379	watches for any child process exit). The watcher will triggered only when	424	using C<0> watches for any child process exit, on others this will
380	the child process has finished and an exit status is available, not on	425	croak). The watcher will be triggered only when the child process has
381	any trace events (stopped/continued).	426	finished and an exit status is available, not on any trace events
		427	(stopped/continued).
382		428
383	The callback will be called with the pid and exit status (as returned by	429	The callback will be called with the pid and exit status (as returned by
384	waitpid), so unlike other watcher types, you I<can> rely on child watcher	430	waitpid), so unlike other watcher types, you I<can> rely on child watcher
385	callback arguments.	431	callback arguments.
386		432
…		…
391		437
392	There is a slight catch to child watchers, however: you usually start them	438	There is a slight catch to child watchers, however: you usually start them
393	I<after> the child process was created, and this means the process could	439	I<after> the child process was created, and this means the process could
394	have exited already (and no SIGCHLD will be sent anymore).	440	have exited already (and no SIGCHLD will be sent anymore).
395		441
396	Not all event models handle this correctly (POE doesn't), but even for	442	Not all event models handle this correctly (neither POE nor IO::Async do,
		443	see their AnyEvent::Impl manpages for details), but even for event models
397	event models that I<do> handle this correctly, they usually need to be	444	that I<do> handle this correctly, they usually need to be loaded before
398	loaded before the process exits (i.e. before you fork in the first place).	445	the process exits (i.e. before you fork in the first place). AnyEvent's
		446	pure perl event loop handles all cases correctly regardless of when you
		447	start the watcher.
399		448
400	This means you cannot create a child watcher as the very first thing in an	449	This means you cannot create a child watcher as the very first
401	AnyEvent program, you I<have> to create at least one watcher before you	450	thing in an AnyEvent program, you I<have> to create at least one
402	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	451	watcher before you C<fork> the child (alternatively, you can call
		452	C<AnyEvent::detect>).
		453
		454	As most event loops do not support waiting for child events, they will be
		455	emulated by AnyEvent in most cases, in which the latency and race problems
		456	mentioned in the description of signal watchers apply.
403		457
404	Example: fork a process and wait for it	458	Example: fork a process and wait for it
405		459
406	my $done = AnyEvent->condvar;	460	my $done = AnyEvent->condvar;
407		461
…		…
419	# do something else, then wait for process exit	473	# do something else, then wait for process exit
420	$done->recv;	474	$done->recv;
421		475
422	=head2 IDLE WATCHERS	476	=head2 IDLE WATCHERS
423		477
		478	$w = AnyEvent->idle (cb => <callback>);
		479
424	Sometimes there is a need to do something, but it is not so important	480	Sometimes there is a need to do something, but it is not so important
425	to do it instantly, but only when there is nothing better to do. This	481	to do it instantly, but only when there is nothing better to do. This
426	"nothing better to do" is usually defined to be "no other events need	482	"nothing better to do" is usually defined to be "no other events need
427	attention by the event loop".	483	attention by the event loop".
428		484
…		…
454	});	510	});
455	});	511	});
456		512
457	=head2 CONDITION VARIABLES	513	=head2 CONDITION VARIABLES
458		514
		515	$cv = AnyEvent->condvar;
		516
		517	$cv->send (<list>);
		518	my @res = $cv->recv;
		519
459	If you are familiar with some event loops you will know that all of them	520	If you are familiar with some event loops you will know that all of them
460	require you to run some blocking "loop", "run" or similar function that	521	require you to run some blocking "loop", "run" or similar function that
461	will actively watch for new events and call your callbacks.	522	will actively watch for new events and call your callbacks.
462		523
463	AnyEvent is different, it expects somebody else to run the event loop and	524	AnyEvent is slightly different: it expects somebody else to run the event
464	will only block when necessary (usually when told by the user).	525	loop and will only block when necessary (usually when told by the user).
465		526
466	The instrument to do that is called a "condition variable", so called	527	The instrument to do that is called a "condition variable", so called
467	because they represent a condition that must become true.	528	because they represent a condition that must become true.
468		529
		530	Now is probably a good time to look at the examples further below.
		531
469	Condition variables can be created by calling the C<< AnyEvent->condvar	532	Condition variables can be created by calling the C<< AnyEvent->condvar
470	>> method, usually without arguments. The only argument pair allowed is	533	>> method, usually without arguments. The only argument pair allowed is
471
472	C<cb>, which specifies a callback to be called when the condition variable	534	C<cb>, which specifies a callback to be called when the condition variable
473	becomes true, with the condition variable as the first argument (but not	535	becomes true, with the condition variable as the first argument (but not
474	the results).	536	the results).
475		537
476	After creation, the condition variable is "false" until it becomes "true"	538	After creation, the condition variable is "false" until it becomes "true"
…		…
481	Condition variables are similar to callbacks, except that you can	543	Condition variables are similar to callbacks, except that you can
482	optionally wait for them. They can also be called merge points - points	544	optionally wait for them. They can also be called merge points - points
483	in time where multiple outstanding events have been processed. And yet	545	in time where multiple outstanding events have been processed. And yet
484	another way to call them is transactions - each condition variable can be	546	another way to call them is transactions - each condition variable can be
485	used to represent a transaction, which finishes at some point and delivers	547	used to represent a transaction, which finishes at some point and delivers
486	a result.	548	a result. And yet some people know them as "futures" - a promise to
		549	compute/deliver something that you can wait for.
487		550
488	Condition variables are very useful to signal that something has finished,	551	Condition variables are very useful to signal that something has finished,
489	for example, if you write a module that does asynchronous http requests,	552	for example, if you write a module that does asynchronous http requests,
490	then a condition variable would be the ideal candidate to signal the	553	then a condition variable would be the ideal candidate to signal the
491	availability of results. The user can either act when the callback is	554	availability of results. The user can either act when the callback is
…		…
525	after => 1,	588	after => 1,
526	cb => sub { $result_ready->send },	589	cb => sub { $result_ready->send },
527	);	590	);
528		591
529	# this "blocks" (while handling events) till the callback	592	# this "blocks" (while handling events) till the callback
530	# calls send	593	# calls -<send
531	$result_ready->recv;	594	$result_ready->recv;
532		595
533	Example: wait for a timer, but take advantage of the fact that	596	Example: wait for a timer, but take advantage of the fact that condition
534	condition variables are also code references.	597	variables are also callable directly.
535		598
536	my $done = AnyEvent->condvar;	599	my $done = AnyEvent->condvar;
537	my $delay = AnyEvent->timer (after => 5, cb => $done);	600	my $delay = AnyEvent->timer (after => 5, cb => $done);
538	$done->recv;	601	$done->recv;
539		602
…		…
545		608
546	...	609	...
547		610
548	my @info = $couchdb->info->recv;	611	my @info = $couchdb->info->recv;
549		612
550	And this is how you would just ste a callback to be called whenever the	613	And this is how you would just set a callback to be called whenever the
551	results are available:	614	results are available:
552		615
553	$couchdb->info->cb (sub {	616	$couchdb->info->cb (sub {
554	my @info = $_[0]->recv;	617	my @info = $_[0]->recv;
555	});	618	});
…		…
573	immediately from within send.	636	immediately from within send.
574		637
575	Any arguments passed to the C<send> call will be returned by all	638	Any arguments passed to the C<send> call will be returned by all
576	future C<< ->recv >> calls.	639	future C<< ->recv >> calls.
577		640
578	Condition variables are overloaded so one can call them directly	641	Condition variables are overloaded so one can call them directly (as if
579	(as a code reference). Calling them directly is the same as calling	642	they were a code reference). Calling them directly is the same as calling
580	C<send>. Note, however, that many C-based event loops do not handle	643	C<send>.
581	overloading, so as tempting as it may be, passing a condition variable
582	instead of a callback does not work. Both the pure perl and EV loops
583	support overloading, however, as well as all functions that use perl to
584	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
585	example).
586		644
587	=item $cv->croak ($error)	645	=item $cv->croak ($error)
588		646
589	Similar to send, but causes all call's to C<< ->recv >> to invoke	647	Similar to send, but causes all call's to C<< ->recv >> to invoke
590	C<Carp::croak> with the given error message/object/scalar.	648	C<Carp::croak> with the given error message/object/scalar.
591		649
592	This can be used to signal any errors to the condition variable	650	This can be used to signal any errors to the condition variable
593	user/consumer.	651	user/consumer. Doing it this way instead of calling C<croak> directly
		652	delays the error detetcion, but has the overwhelmign advantage that it
		653	diagnoses the error at the place where the result is expected, and not
		654	deep in some event clalback without connection to the actual code causing
		655	the problem.
594		656
595	=item $cv->begin ([group callback])	657	=item $cv->begin ([group callback])
596		658
597	=item $cv->end	659	=item $cv->end
598
599	These two methods are EXPERIMENTAL and MIGHT CHANGE.
600		660
601	These two methods can be used to combine many transactions/events into	661	These two methods can be used to combine many transactions/events into
602	one. For example, a function that pings many hosts in parallel might want	662	one. For example, a function that pings many hosts in parallel might want
603	to use a condition variable for the whole process.	663	to use a condition variable for the whole process.
604		664
…		…
606	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	666	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
607	>>, the (last) callback passed to C<begin> will be executed. That callback	667	>>, the (last) callback passed to C<begin> will be executed. That callback
608	is I<supposed> to call C<< ->send >>, but that is not required. If no	668	is I<supposed> to call C<< ->send >>, but that is not required. If no
609	callback was set, C<send> will be called without any arguments.	669	callback was set, C<send> will be called without any arguments.
610		670
611	Let's clarify this with the ping example:	671	You can think of C<< $cv->send >> giving you an OR condition (one call
		672	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		673	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		674
		675	Let's start with a simple example: you have two I/O watchers (for example,
		676	STDOUT and STDERR for a program), and you want to wait for both streams to
		677	close before activating a condvar:
		678
		679	my $cv = AnyEvent->condvar;
		680
		681	$cv->begin; # first watcher
		682	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		683	defined sysread $fh1, my $buf, 4096
		684	or $cv->end;
		685	});
		686
		687	$cv->begin; # second watcher
		688	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		689	defined sysread $fh2, my $buf, 4096
		690	or $cv->end;
		691	});
		692
		693	$cv->recv;
		694
		695	This works because for every event source (EOF on file handle), there is
		696	one call to C<begin>, so the condvar waits for all calls to C<end> before
		697	sending.
		698
		699	The ping example mentioned above is slightly more complicated, as the
		700	there are results to be passwd back, and the number of tasks that are
		701	begung can potentially be zero:
612		702
613	my $cv = AnyEvent->condvar;	703	my $cv = AnyEvent->condvar;
614		704
615	my %result;	705	my %result;
616	$cv->begin (sub { $cv->send (\%result) });	706	$cv->begin (sub { $cv->send (\%result) });
…		…
636	loop, which serves two important purposes: first, it sets the callback	726	loop, which serves two important purposes: first, it sets the callback
637	to be called once the counter reaches C<0>, and second, it ensures that	727	to be called once the counter reaches C<0>, and second, it ensures that
638	C<send> is called even when C<no> hosts are being pinged (the loop	728	C<send> is called even when C<no> hosts are being pinged (the loop
639	doesn't execute once).	729	doesn't execute once).
640		730
641	This is the general pattern when you "fan out" into multiple subrequests:	731	This is the general pattern when you "fan out" into multiple (but
642	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	732	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
643	is called at least once, and then, for each subrequest you start, call	733	the callback and ensure C<end> is called at least once, and then, for each
644	C<begin> and for each subrequest you finish, call C<end>.	734	subrequest you start, call C<begin> and for each subrequest you finish,
		735	call C<end>.
645		736
646	=back	737	=back
647		738
648	=head3 METHODS FOR CONSUMERS	739	=head3 METHODS FOR CONSUMERS
649		740
…		…
665	function will call C<croak>.	756	function will call C<croak>.
666		757
667	In list context, all parameters passed to C<send> will be returned,	758	In list context, all parameters passed to C<send> will be returned,
668	in scalar context only the first one will be returned.	759	in scalar context only the first one will be returned.
669		760
		761	Note that doing a blocking wait in a callback is not supported by any
		762	event loop, that is, recursive invocation of a blocking C<< ->recv
		763	>> is not allowed, and the C<recv> call will C<croak> if such a
		764	condition is detected. This condition can be slightly loosened by using
		765	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		766	any thread that doesn't run the event loop itself.
		767
670	Not all event models support a blocking wait - some die in that case	768	Not all event models support a blocking wait - some die in that case
671	(programs might want to do that to stay interactive), so I<if you are	769	(programs might want to do that to stay interactive), so I<if you are
672	using this from a module, never require a blocking wait>, but let the	770	using this from a module, never require a blocking wait>. Instead, let the
673	caller decide whether the call will block or not (for example, by coupling	771	caller decide whether the call will block or not (for example, by coupling
674	condition variables with some kind of request results and supporting	772	condition variables with some kind of request results and supporting
675	callbacks so the caller knows that getting the result will not block,	773	callbacks so the caller knows that getting the result will not block,
676	while still supporting blocking waits if the caller so desires).	774	while still supporting blocking waits if the caller so desires).
677		775
678	Another reason I<never> to C<< ->recv >> in a module is that you cannot
679	sensibly have two C<< ->recv >>'s in parallel, as that would require
680	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
681	can supply.
682
683	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
684	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
685	versions and also integrates coroutines into AnyEvent, making blocking
686	C<< ->recv >> calls perfectly safe as long as they are done from another
687	coroutine (one that doesn't run the event loop).
688
689	You can ensure that C<< -recv >> never blocks by setting a callback and	776	You can ensure that C<< -recv >> never blocks by setting a callback and
690	only calling C<< ->recv >> from within that callback (or at a later	777	only calling C<< ->recv >> from within that callback (or at a later
691	time). This will work even when the event loop does not support blocking	778	time). This will work even when the event loop does not support blocking
692	waits otherwise.	779	waits otherwise.
693		780
…		…
706	variable itself. Calling C<recv> inside the callback or at any later time	793	variable itself. Calling C<recv> inside the callback or at any later time
707	is guaranteed not to block.	794	is guaranteed not to block.
708		795
709	=back	796	=back
710		797
		798	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		799
		800	The available backend classes are (every class has its own manpage):
		801
		802	=over 4
		803
		804	=item Backends that are autoprobed when no other event loop can be found.
		805
		806	EV is the preferred backend when no other event loop seems to be in
		807	use. If EV is not installed, then AnyEvent will try Event, and, failing
		808	that, will fall back to its own pure-perl implementation, which is
		809	available everywhere as it comes with AnyEvent itself.
		810
		811	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		812	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		813	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		814
		815	=item Backends that are transparently being picked up when they are used.
		816
		817	These will be used when they are currently loaded when the first watcher
		818	is created, in which case it is assumed that the application is using
		819	them. This means that AnyEvent will automatically pick the right backend
		820	when the main program loads an event module before anything starts to
		821	create watchers. Nothing special needs to be done by the main program.
		822
		823	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		824	AnyEvent::Impl::Tk based on Tk, very broken.
		825	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		826	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		827	AnyEvent::Impl::Irssi used when running within irssi.
		828
		829	=item Backends with special needs.
		830
		831	Qt requires the Qt::Application to be instantiated first, but will
		832	otherwise be picked up automatically. As long as the main program
		833	instantiates the application before any AnyEvent watchers are created,
		834	everything should just work.
		835
		836	AnyEvent::Impl::Qt based on Qt.
		837
		838	Support for IO::Async can only be partial, as it is too broken and
		839	architecturally limited to even support the AnyEvent API. It also
		840	is the only event loop that needs the loop to be set explicitly, so
		841	it can only be used by a main program knowing about AnyEvent. See
		842	L<AnyEvent::Impl::Async> for the gory details.
		843
		844	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		845
		846	=item Event loops that are indirectly supported via other backends.
		847
		848	Some event loops can be supported via other modules:
		849
		850	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		851
		852	B<WxWidgets> has no support for watching file handles. However, you can
		853	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		854	polls 20 times per second, which was considered to be too horrible to even
		855	consider for AnyEvent.
		856
		857	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		858	backend, so it can be supported through POE.
		859
		860	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		861	load L<POE> when detecting them, in the hope that POE will pick them up,
		862	in which case everything will be automatic.
		863
		864	=back
		865
711	=head1 GLOBAL VARIABLES AND FUNCTIONS	866	=head1 GLOBAL VARIABLES AND FUNCTIONS
712		867
		868	These are not normally required to use AnyEvent, but can be useful to
		869	write AnyEvent extension modules.
		870
713	=over 4	871	=over 4
714		872
715	=item $AnyEvent::MODEL	873	=item $AnyEvent::MODEL
716		874
717	Contains C<undef> until the first watcher is being created. Then it	875	Contains C<undef> until the first watcher is being created, before the
		876	backend has been autodetected.
		877
718	contains the event model that is being used, which is the name of the	878	Afterwards it contains the event model that is being used, which is the
719	Perl class implementing the model. This class is usually one of the	879	name of the Perl class implementing the model. This class is usually one
720	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	880	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
721	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	881	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
722		882	will be C<urxvt::anyevent>).
723	The known classes so far are:
724
725	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
726	AnyEvent::Impl::Event based on Event, second best choice.
727	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
728	AnyEvent::Impl::Glib based on Glib, third-best choice.
729	AnyEvent::Impl::Tk based on Tk, very bad choice.
730	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
731	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
732	AnyEvent::Impl::POE based on POE, not generic enough for full support.
733
734	There is no support for WxWidgets, as WxWidgets has no support for
735	watching file handles. However, you can use WxWidgets through the
736	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
737	second, which was considered to be too horrible to even consider for
738	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
739	it's adaptor.
740
741	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
742	autodetecting them.
743		883
744	=item AnyEvent::detect	884	=item AnyEvent::detect
745		885
746	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	886	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
747	if necessary. You should only call this function right before you would	887	if necessary. You should only call this function right before you would
748	have created an AnyEvent watcher anyway, that is, as late as possible at	888	have created an AnyEvent watcher anyway, that is, as late as possible at
749	runtime.	889	runtime, and not e.g. while initialising of your module.
		890
		891	If you need to do some initialisation before AnyEvent watchers are
		892	created, use C<post_detect>.
750		893
751	=item $guard = AnyEvent::post_detect { BLOCK }	894	=item $guard = AnyEvent::post_detect { BLOCK }
752		895
753	Arranges for the code block to be executed as soon as the event model is	896	Arranges for the code block to be executed as soon as the event model is
754	autodetected (or immediately if this has already happened).	897	autodetected (or immediately if this has already happened).
755		898
		899	The block will be executed I<after> the actual backend has been detected
		900	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		901	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		902	other initialisations - see the sources of L<AnyEvent::Strict> or
		903	L<AnyEvent::AIO> to see how this is used.
		904
		905	The most common usage is to create some global watchers, without forcing
		906	event module detection too early, for example, L<AnyEvent::AIO> creates
		907	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		908	avoid autodetecting the event module at load time.
		909
756	If called in scalar or list context, then it creates and returns an object	910	If called in scalar or list context, then it creates and returns an object
757	that automatically removes the callback again when it is destroyed. See	911	that automatically removes the callback again when it is destroyed (or
		912	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
758	L<Coro::BDB> for a case where this is useful.	913	a case where this is useful.
		914
		915	Example: Create a watcher for the IO::AIO module and store it in
		916	C<$WATCHER>. Only do so after the event loop is initialised, though.
		917
		918	our WATCHER;
		919
		920	my $guard = AnyEvent::post_detect {
		921	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		922	};
		923
		924	# the ||= is important in case post_detect immediately runs the block,
		925	# as to not clobber the newly-created watcher. assigning both watcher and
		926	# post_detect guard to the same variable has the advantage of users being
		927	# able to just C<undef $WATCHER> if the watcher causes them grief.
		928
		929	$WATCHER ||= $guard;
759		930
760	=item @AnyEvent::post_detect	931	=item @AnyEvent::post_detect
761		932
762	If there are any code references in this array (you can C<push> to it	933	If there are any code references in this array (you can C<push> to it
763	before or after loading AnyEvent), then they will called directly after	934	before or after loading AnyEvent), then they will called directly after
764	the event loop has been chosen.	935	the event loop has been chosen.
765		936
766	You should check C<$AnyEvent::MODEL> before adding to this array, though:	937	You should check C<$AnyEvent::MODEL> before adding to this array, though:
767	if it contains a true value then the event loop has already been detected,	938	if it is defined then the event loop has already been detected, and the
768	and the array will be ignored.	939	array will be ignored.
769		940
770	Best use C<AnyEvent::post_detect { BLOCK }> instead.	941	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		942	it,as it takes care of these details.
		943
		944	This variable is mainly useful for modules that can do something useful
		945	when AnyEvent is used and thus want to know when it is initialised, but do
		946	not need to even load it by default. This array provides the means to hook
		947	into AnyEvent passively, without loading it.
771		948
772	=back	949	=back
773		950
774	=head1 WHAT TO DO IN A MODULE	951	=head1 WHAT TO DO IN A MODULE
775		952
…		…
830		1007
831		1008
832	=head1 OTHER MODULES	1009	=head1 OTHER MODULES
833		1010
834	The following is a non-exhaustive list of additional modules that use	1011	The following is a non-exhaustive list of additional modules that use
835	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1012	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
836	in the same program. Some of the modules come with AnyEvent, some are	1013	modules and other event loops in the same program. Some of the modules
837	available via CPAN.	1014	come with AnyEvent, most are available via CPAN.
838		1015
839	=over 4	1016	=over 4
840		1017
841	=item L<AnyEvent::Util>	1018	=item L<AnyEvent::Util>
842		1019
…		…
851		1028
852	=item L<AnyEvent::Handle>	1029	=item L<AnyEvent::Handle>
853		1030
854	Provide read and write buffers, manages watchers for reads and writes,	1031	Provide read and write buffers, manages watchers for reads and writes,
855	supports raw and formatted I/O, I/O queued and fully transparent and	1032	supports raw and formatted I/O, I/O queued and fully transparent and
856	non-blocking SSL/TLS.	1033	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
857		1034
858	=item L<AnyEvent::DNS>	1035	=item L<AnyEvent::DNS>
859		1036
860	Provides rich asynchronous DNS resolver capabilities.	1037	Provides rich asynchronous DNS resolver capabilities.
861		1038
…		…
889		1066
890	=item L<AnyEvent::GPSD>	1067	=item L<AnyEvent::GPSD>
891		1068
892	A non-blocking interface to gpsd, a daemon delivering GPS information.	1069	A non-blocking interface to gpsd, a daemon delivering GPS information.
893		1070
		1071	=item L<AnyEvent::IRC>
		1072
		1073	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1074
		1075	=item L<AnyEvent::XMPP>
		1076
		1077	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1078	Net::XMPP2>.
		1079
894	=item L<AnyEvent::IGS>	1080	=item L<AnyEvent::IGS>
895		1081
896	A non-blocking interface to the Internet Go Server protocol (used by	1082	A non-blocking interface to the Internet Go Server protocol (used by
897	L<App::IGS>).	1083	L<App::IGS>).
898		1084
899	=item L<AnyEvent::IRC>
900
901	AnyEvent based IRC client module family (replacing the older Net::IRC3).
902
903	=item L<Net::XMPP2>
904
905	AnyEvent based XMPP (Jabber protocol) module family.
906
907	=item L<Net::FCP>	1085	=item L<Net::FCP>
908		1086
909	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1087	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
910	of AnyEvent.	1088	of AnyEvent.
911		1089
…		…
915		1093
916	=item L<Coro>	1094	=item L<Coro>
917		1095
918	Has special support for AnyEvent via L<Coro::AnyEvent>.	1096	Has special support for AnyEvent via L<Coro::AnyEvent>.
919		1097
920	=item L<IO::Lambda>
921
922	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
923
924	=back	1098	=back
925		1099
926	=cut	1100	=cut
927		1101
928	package AnyEvent;	1102	package AnyEvent;
929		1103
		1104	# basically a tuned-down version of common::sense
		1105	sub common_sense {
930	no warnings;	1106	# no warnings
		1107	${^WARNING_BITS} ^= ${^WARNING_BITS};
931	use strict qw(vars subs);	1108	# use strict vars subs
		1109	$^H |= 0x00000600;
		1110	}
932		1111
		1112	BEGIN { AnyEvent::common_sense }
		1113
933	use Carp;	1114	use Carp ();
934		1115
935	our $VERSION = 4.4;	1116	our $VERSION = 4.881;
936	our $MODEL;	1117	our $MODEL;
937		1118
938	our $AUTOLOAD;	1119	our $AUTOLOAD;
939	our @ISA;	1120	our @ISA;
940		1121
941	our @REGISTRY;	1122	our @REGISTRY;
942		1123
943	our $WIN32;	1124	our $WIN32;
944		1125
		1126	our $VERBOSE;
		1127
945	BEGIN {	1128	BEGIN {
946	my $win32 = ! ! ($^O =~ /mswin32/i);	1129	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
947	eval "sub WIN32(){ $win32 }";	1130	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
948	}
949		1131
		1132	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1133	if ${^TAINT};
		1134
950	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1135	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1136
		1137	}
		1138
		1139	our $MAX_SIGNAL_LATENCY = 10;
951		1140
952	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1141	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
953		1142
954	{	1143	{
955	my $idx;	1144	my $idx;
…		…
957	for reverse split /\s*,\s*/,	1146	for reverse split /\s*,\s*/,
958	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1147	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
959	}	1148	}
960		1149
961	my @models = (	1150	my @models = (
962	[EV:: => AnyEvent::Impl::EV::],	1151	[EV:: => AnyEvent::Impl::EV:: , 1],
963	[Event:: => AnyEvent::Impl::Event::],	1152	[Event:: => AnyEvent::Impl::Event::, 1],
964	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1153	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
965	# everything below here will not be autoprobed	1154	# everything below here will not (normally) be autoprobed
966	# as the pureperl backend should work everywhere	1155	# as the pureperl backend should work everywhere
967	# and is usually faster	1156	# and is usually faster
		1157	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1158	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1159	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
968	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1160	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
969	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
970	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
971	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1161	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
972	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1162	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
973	[Wx:: => AnyEvent::Impl::POE::],	1163	[Wx:: => AnyEvent::Impl::POE::],
974	[Prima:: => AnyEvent::Impl::POE::],	1164	[Prima:: => AnyEvent::Impl::POE::],
		1165	# IO::Async is just too broken - we would need workarounds for its
		1166	# byzantine signal and broken child handling, among others.
		1167	# IO::Async is rather hard to detect, as it doesn't have any
		1168	# obvious default class.
		1169	# [0, IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1170	# [0, IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1171	# [0, IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
975	);	1172	);
976		1173
977	our %method = map +($_ => 1),	1174	our %method = map +($_ => 1),
978	qw(io timer time now now_update signal child idle condvar one_event DESTROY);	1175	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
979		1176
…		…
983	my ($cb) = @_;	1180	my ($cb) = @_;
984		1181
985	if ($MODEL) {	1182	if ($MODEL) {
986	$cb->();	1183	$cb->();
987		1184
988	1	1185	undef
989	} else {	1186	} else {
990	push @post_detect, $cb;	1187	push @post_detect, $cb;
991		1188
992	defined wantarray	1189	defined wantarray
993	? bless \$cb, "AnyEvent::Util::postdetect"	1190	? bless \$cb, "AnyEvent::Util::postdetect"
…		…
999	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1196	@post_detect = grep $_ != ${$_[0]}, @post_detect;
1000	}	1197	}
1001		1198
1002	sub detect() {	1199	sub detect() {
1003	unless ($MODEL) {	1200	unless ($MODEL) {
1004	no strict 'refs';
1005	local $SIG{__DIE__};	1201	local $SIG{__DIE__};
1006		1202
1007	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1203	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
1008	my $model = "AnyEvent::Impl::$1";	1204	my $model = "AnyEvent::Impl::$1";
1009	if (eval "require $model") {	1205	if (eval "require $model") {
1010	$MODEL = $model;	1206	$MODEL = $model;
1011	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1207	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
1012	} else {	1208	} else {
1013	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1209	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
1014	}	1210	}
1015	}	1211	}
1016		1212
1017	# check for already loaded models	1213	# check for already loaded models
1018	unless ($MODEL) {	1214	unless ($MODEL) {
1019	for (@REGISTRY, @models) {	1215	for (@REGISTRY, @models) {
1020	my ($package, $model) = @$_;	1216	my ($package, $model) = @$_;
1021	if (${"$package\::VERSION"} > 0) {	1217	if (${"$package\::VERSION"} > 0) {
1022	if (eval "require $model") {	1218	if (eval "require $model") {
1023	$MODEL = $model;	1219	$MODEL = $model;
1024	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1220	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
1025	last;	1221	last;
1026	}	1222	}
1027	}	1223	}
1028	}	1224	}
1029		1225
1030	unless ($MODEL) {	1226	unless ($MODEL) {
1031	# try to load a model	1227	# try to autoload a model
1032
1033	for (@REGISTRY, @models) {	1228	for (@REGISTRY, @models) {
1034	my ($package, $model) = @$_;	1229	my ($package, $model, $autoload) = @$_;
		1230	if (
		1231	$autoload
1035	if (eval "require $package"	1232	and eval "require $package"
1036	and ${"$package\::VERSION"} > 0	1233	and ${"$package\::VERSION"} > 0
1037	and eval "require $model") {	1234	and eval "require $model"
		1235	) {
1038	$MODEL = $model;	1236	$MODEL = $model;
1039	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1237	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
1040	last;	1238	last;
1041	}	1239	}
1042	}	1240	}
1043		1241
1044	$MODEL	1242	$MODEL
…		…
1060		1258
1061	sub AUTOLOAD {	1259	sub AUTOLOAD {
1062	(my $func = $AUTOLOAD) =~ s/.*://;	1260	(my $func = $AUTOLOAD) =~ s/.*://;
1063		1261
1064	$method{$func}	1262	$method{$func}
1065	or croak "$func: not a valid method for AnyEvent objects";	1263	or Carp::croak "$func: not a valid method for AnyEvent objects";
1066		1264
1067	detect unless $MODEL;	1265	detect unless $MODEL;
1068		1266
1069	my $class = shift;	1267	my $class = shift;
1070	$class->$func (@_);	1268	$class->$func (@_);
1071	}	1269	}
1072		1270
1073	# utility function to dup a filehandle. this is used by many backends	1271	# utility function to dup a filehandle. this is used by many backends
1074	# to support binding more than one watcher per filehandle (they usually	1272	# to support binding more than one watcher per filehandle (they usually
1075	# allow only one watcher per fd, so we dup it to get a different one).	1273	# allow only one watcher per fd, so we dup it to get a different one).
1076	sub _dupfh($$$$) {	1274	sub _dupfh($$;$$) {
1077	my ($poll, $fh, $r, $w) = @_;	1275	my ($poll, $fh, $r, $w) = @_;
1078		1276
1079	# cygwin requires the fh mode to be matching, unix doesn't	1277	# cygwin requires the fh mode to be matching, unix doesn't
1080	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1278	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1081	: $poll eq "w" ? ($w, ">")
1082	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1083		1279
1084	open my $fh2, "$mode&" . fileno $fh	1280	open my $fh2, $mode, $fh
1085	or die "cannot dup() filehandle: $!,";	1281	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1086		1282
1087	# we assume CLOEXEC is already set by perl in all important cases	1283	# we assume CLOEXEC is already set by perl in all important cases
1088		1284
1089	($fh2, $rw)	1285	($fh2, $rw)
1090	}	1286	}
1091		1287
1092	package AnyEvent::Base;	1288	package AnyEvent::Base;
1093		1289
1094	# default implementations for many methods	1290	# default implementations for many methods
1095		1291
1096	BEGIN {	1292	sub _time {
		1293	# probe for availability of Time::HiRes
1097	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {	1294	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1295	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1098	*_time = \&Time::HiRes::time;	1296	*_time = \&Time::HiRes::time;
1099	# if (eval "use POSIX (); (POSIX::times())...	1297	# if (eval "use POSIX (); (POSIX::times())...
1100	} else {	1298	} else {
		1299	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1101	*_time = sub { time }; # epic fail	1300	*_time = sub { time }; # epic fail
1102	}	1301	}
		1302
		1303	&_time
1103	}	1304	}
1104		1305
1105	sub time { _time }	1306	sub time { _time }
1106	sub now { _time }	1307	sub now { _time }
1107	sub now_update { }	1308	sub now_update { }
…		…
1112	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"	1313	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1113	}	1314	}
1114		1315
1115	# default implementation for ->signal	1316	# default implementation for ->signal
1116		1317
		1318	our $HAVE_ASYNC_INTERRUPT;
		1319
		1320	sub _have_async_interrupt() {
		1321	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1322	&& eval "use Async::Interrupt 1.0 (); 1")
		1323	unless defined $HAVE_ASYNC_INTERRUPT;
		1324
		1325	$HAVE_ASYNC_INTERRUPT
		1326	}
		1327
1117	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1328	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1329	our (%SIG_ASY, %SIG_ASY_W);
		1330	our ($SIG_COUNT, $SIG_TW);
1118		1331
1119	sub _signal_exec {	1332	sub _signal_exec {
		1333	$HAVE_ASYNC_INTERRUPT
		1334	? $SIGPIPE_R->drain
1120	sysread $SIGPIPE_R, my $dummy, 4;	1335	: sysread $SIGPIPE_R, my $dummy, 9;
1121		1336
1122	while (%SIG_EV) {	1337	while (%SIG_EV) {
1123	for (keys %SIG_EV) {	1338	for (keys %SIG_EV) {
1124	delete $SIG_EV{$_};	1339	delete $SIG_EV{$_};
1125	$_->() for values %{ $SIG_CB{$_} || {} };	1340	$_->() for values %{ $SIG_CB{$_} || {} };
1126	}	1341	}
1127	}	1342	}
1128	}	1343	}
1129		1344
		1345	# install a dummy wakeup watcher to reduce signal catching latency
		1346	sub _sig_add() {
		1347	unless ($SIG_COUNT++) {
		1348	# try to align timer on a full-second boundary, if possible
		1349	my $NOW = AnyEvent->now;
		1350
		1351	$SIG_TW = AnyEvent->timer (
		1352	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1353	interval => $MAX_SIGNAL_LATENCY,
		1354	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1355	);
		1356	}
		1357	}
		1358
		1359	sub _sig_del {
		1360	undef $SIG_TW
		1361	unless --$SIG_COUNT;
		1362	}
		1363
		1364	our $_sig_name_init; $_sig_name_init = sub {
		1365	eval q{ # poor man's autoloading
		1366	undef $_sig_name_init;
		1367
		1368	if (_have_async_interrupt) {
		1369	*sig2num = \&Async::Interrupt::sig2num;
		1370	*sig2name = \&Async::Interrupt::sig2name;
		1371	} else {
		1372	require Config;
		1373
		1374	my %signame2num;
		1375	@signame2num{ split ' ', $Config::Config{sig_name} }
		1376	= split ' ', $Config::Config{sig_num};
		1377
		1378	my @signum2name;
		1379	@signum2name[values %signame2num] = keys %signame2num;
		1380
		1381	*sig2num = sub($) {
		1382	$_[0] > 0 ? shift : $signame2num{+shift}
		1383	};
		1384	*sig2name = sub ($) {
		1385	$_[0] > 0 ? $signum2name[+shift] : shift
		1386	};
		1387	}
		1388	};
		1389	die if $@;
		1390	};
		1391
		1392	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1393	sub sig2name($) { &$_sig_name_init; &sig2name }
		1394
1130	sub signal {	1395	sub signal {
1131	my (undef, %arg) = @_;	1396	eval q{ # poor man's autoloading {}
		1397	# probe for availability of Async::Interrupt
		1398	if (_have_async_interrupt) {
		1399	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1132		1400
1133	unless ($SIGPIPE_R) {	1401	$SIGPIPE_R = new Async::Interrupt::EventPipe;
1134	require Fcntl;	1402	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
1135		1403
1136	if (AnyEvent::WIN32) {
1137	require AnyEvent::Util;
1138
1139	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1140	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1141	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1142	} else {	1404	} else {
		1405	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1406
		1407	require Fcntl;
		1408
		1409	if (AnyEvent::WIN32) {
		1410	require AnyEvent::Util;
		1411
		1412	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1413	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1414	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1415	} else {
1143	pipe $SIGPIPE_R, $SIGPIPE_W;	1416	pipe $SIGPIPE_R, $SIGPIPE_W;
1144	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1417	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1145	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1418	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1419
		1420	# not strictly required, as $^F is normally 2, but let's make sure...
		1421	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1422	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1423	}
		1424
		1425	$SIGPIPE_R
		1426	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1427
		1428	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1146	}	1429	}
1147		1430
1148	$SIGPIPE_R	1431	*signal = sub {
1149	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1432	my (undef, %arg) = @_;
1150		1433
1151	# not strictly required, as $^F is normally 2, but let's make sure...
1152	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1153	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1154
1155	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1156	}
1157
1158	my $signal = uc $arg{signal}	1434	my $signal = uc $arg{signal}
1159	or Carp::croak "required option 'signal' is missing";	1435	or Carp::croak "required option 'signal' is missing";
1160		1436
		1437	if ($HAVE_ASYNC_INTERRUPT) {
		1438	# async::interrupt
		1439
		1440	$signal = sig2num $signal;
1161	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1441	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1442
		1443	$SIG_ASY{$signal} ||= new Async::Interrupt
		1444	cb => sub { undef $SIG_EV{$signal} },
		1445	signal => $signal,
		1446	pipe => [$SIGPIPE_R->filenos],
		1447	pipe_autodrain => 0,
		1448	;
		1449
		1450	} else {
		1451	# pure perl
		1452
		1453	# AE::Util has been loaded in signal
		1454	$signal = sig2name $signal;
		1455	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1456
1162	$SIG{$signal} ||= sub {	1457	$SIG{$signal} ||= sub {
1163	local $!;	1458	local $!;
1164	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;	1459	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1165	undef $SIG_EV{$signal};	1460	undef $SIG_EV{$signal};
		1461	};
		1462
		1463	# can't do signal processing without introducing races in pure perl,
		1464	# so limit the signal latency.
		1465	_sig_add;
		1466	}
		1467
		1468	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1469	};
		1470
		1471	*AnyEvent::Base::signal::DESTROY = sub {
		1472	my ($signal, $cb) = @{$_[0]};
		1473
		1474	_sig_del;
		1475
		1476	delete $SIG_CB{$signal}{$cb};
		1477
		1478	$HAVE_ASYNC_INTERRUPT
		1479	? delete $SIG_ASY{$signal}
		1480	: # delete doesn't work with older perls - they then
		1481	# print weird messages, or just unconditionally exit
		1482	# instead of getting the default action.
		1483	undef $SIG{$signal}
		1484	unless keys %{ $SIG_CB{$signal} };
		1485	};
1166	};	1486	};
1167		1487	die if $@;
1168	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"	1488	&signal
1169	}
1170
1171	sub AnyEvent::Base::signal::DESTROY {
1172	my ($signal, $cb) = @{$_[0]};
1173
1174	delete $SIG_CB{$signal}{$cb};
1175
1176	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1177	}	1489	}
1178		1490
1179	# default implementation for ->child	1491	# default implementation for ->child
1180		1492
1181	our %PID_CB;	1493	our %PID_CB;
1182	our $CHLD_W;	1494	our $CHLD_W;
1183	our $CHLD_DELAY_W;	1495	our $CHLD_DELAY_W;
1184	our $PID_IDLE;
1185	our $WNOHANG;	1496	our $WNOHANG;
1186		1497
1187	sub _child_wait {	1498	sub _emit_childstatus($$) {
1188	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1499	my (undef, $rpid, $rstatus) = @_;
		1500
		1501	$_->($rpid, $rstatus)
1189	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1502	for values %{ $PID_CB{$rpid} || {} },
1190	(values %{ $PID_CB{0} || {} });	1503	values %{ $PID_CB{0} || {} };
1191	}
1192
1193	undef $PID_IDLE;
1194	}	1504	}
1195		1505
1196	sub _sigchld {	1506	sub _sigchld {
1197	# make sure we deliver these changes "synchronous" with the event loop.	1507	my $pid;
1198	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1508
1199	undef $CHLD_DELAY_W;	1509	AnyEvent->_emit_childstatus ($pid, $?)
1200	&_child_wait;	1510	while ($pid = waitpid -1, $WNOHANG) > 0;
1201	});
1202	}	1511	}
1203		1512
1204	sub child {	1513	sub child {
1205	my (undef, %arg) = @_;	1514	my (undef, %arg) = @_;
1206		1515
1207	defined (my $pid = $arg{pid} + 0)	1516	defined (my $pid = $arg{pid} + 0)
1208	or Carp::croak "required option 'pid' is missing";	1517	or Carp::croak "required option 'pid' is missing";
1209		1518
1210	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1519	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1211		1520
1212	unless ($WNOHANG) {	1521	# WNOHANG is almost cetrainly 1 everywhere
		1522	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1523	? 1
1213	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1524	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1214	}
1215		1525
1216	unless ($CHLD_W) {	1526	unless ($CHLD_W) {
1217	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1527	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1218	# child could be a zombie already, so make at least one round	1528	# child could be a zombie already, so make at least one round
1219	&_sigchld;	1529	&_sigchld;
…		…
1230		1540
1231	undef $CHLD_W unless keys %PID_CB;	1541	undef $CHLD_W unless keys %PID_CB;
1232	}	1542	}
1233		1543
1234	# idle emulation is done by simply using a timer, regardless	1544	# idle emulation is done by simply using a timer, regardless
1235	# of whether the proces sis idle or not, and not letting	1545	# of whether the process is idle or not, and not letting
1236	# the callback use more than 50% of the time.	1546	# the callback use more than 50% of the time.
1237	sub idle {	1547	sub idle {
1238	my (undef, %arg) = @_;	1548	my (undef, %arg) = @_;
1239		1549
1240	my ($cb, $w, $rcb) = $arg{cb};	1550	my ($cb, $w, $rcb) = $arg{cb};
…		…
1271		1581
1272	our @ISA = AnyEvent::CondVar::Base::;	1582	our @ISA = AnyEvent::CondVar::Base::;
1273		1583
1274	package AnyEvent::CondVar::Base;	1584	package AnyEvent::CondVar::Base;
1275		1585
1276	use overload	1586	#use overload
1277	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1587	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1278	fallback => 1;	1588	# fallback => 1;
		1589
		1590	# save 300+ kilobytes by dirtily hardcoding overloading
		1591	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1592	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1593	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1594	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1595
		1596	our $WAITING;
1279		1597
1280	sub _send {	1598	sub _send {
1281	# nop	1599	# nop
1282	}	1600	}
1283		1601
…		…
1296	sub ready {	1614	sub ready {
1297	$_[0]{_ae_sent}	1615	$_[0]{_ae_sent}
1298	}	1616	}
1299		1617
1300	sub _wait {	1618	sub _wait {
		1619	$WAITING
		1620	and !$_[0]{_ae_sent}
		1621	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1622
		1623	local $WAITING = 1;
1301	AnyEvent->one_event while !$_[0]{_ae_sent};	1624	AnyEvent->one_event while !$_[0]{_ae_sent};
1302	}	1625	}
1303		1626
1304	sub recv {	1627	sub recv {
1305	$_[0]->_wait;	1628	$_[0]->_wait;
…		…
1324	}	1647	}
1325		1648
1326	# undocumented/compatibility with pre-3.4	1649	# undocumented/compatibility with pre-3.4
1327	*broadcast = \&send;	1650	*broadcast = \&send;
1328	*wait = \&_wait;	1651	*wait = \&_wait;
		1652
		1653	#############################################################################
		1654	# "new" API, currently only emulation of it
		1655	#############################################################################
		1656
		1657	package AE;
		1658
		1659	sub io($$$) {
		1660	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1661	}
		1662
		1663	sub timer($$$) {
		1664	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2]);
		1665	}
		1666
		1667	sub signal($$) {
		1668	AnyEvent->signal (signal => $_[0], cb => $_[1]);
		1669	}
		1670
		1671	sub child($$) {
		1672	AnyEvent->child (pid => $_[0], cb => $_[1]);
		1673	}
		1674
		1675	sub idle($) {
		1676	AnyEvent->idle (cb => $_[0]);
		1677	}
		1678
		1679	sub cv() {
		1680	AnyEvent->condvar
		1681	}
		1682
		1683	sub now() {
		1684	AnyEvent->now
		1685	}
		1686
		1687	sub now_update() {
		1688	AnyEvent->now_update
		1689	}
		1690
		1691	sub time() {
		1692	AnyEvent->time
		1693	}
1329		1694
1330	=head1 ERROR AND EXCEPTION HANDLING	1695	=head1 ERROR AND EXCEPTION HANDLING
1331		1696
1332	In general, AnyEvent does not do any error handling - it relies on the	1697	In general, AnyEvent does not do any error handling - it relies on the
1333	caller to do that if required. The L<AnyEvent::Strict> module (see also	1698	caller to do that if required. The L<AnyEvent::Strict> module (see also
…		…
1346	so on.	1711	so on.
1347		1712
1348	=head1 ENVIRONMENT VARIABLES	1713	=head1 ENVIRONMENT VARIABLES
1349		1714
1350	The following environment variables are used by this module or its	1715	The following environment variables are used by this module or its
1351	submodules:	1716	submodules.
		1717
		1718	Note that AnyEvent will remove I<all> environment variables starting with
		1719	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1720	enabled.
1352		1721
1353	=over 4	1722	=over 4
1354		1723
1355	=item C<PERL_ANYEVENT_VERBOSE>	1724	=item C<PERL_ANYEVENT_VERBOSE>
1356		1725
…		…
1363	C<PERL_ANYEVENT_MODEL>.	1732	C<PERL_ANYEVENT_MODEL>.
1364		1733
1365	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1734	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1366	model it chooses.	1735	model it chooses.
1367		1736
		1737	When set to C<8> or higher, then AnyEvent will report extra information on
		1738	which optional modules it loads and how it implements certain features.
		1739
1368	=item C<PERL_ANYEVENT_STRICT>	1740	=item C<PERL_ANYEVENT_STRICT>
1369		1741
1370	AnyEvent does not do much argument checking by default, as thorough	1742	AnyEvent does not do much argument checking by default, as thorough
1371	argument checking is very costly. Setting this variable to a true value	1743	argument checking is very costly. Setting this variable to a true value
1372	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1744	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1373	check the arguments passed to most method calls. If it finds any problems	1745	check the arguments passed to most method calls. If it finds any problems,
1374	it will croak.	1746	it will croak.
1375		1747
1376	In other words, enables "strict" mode.	1748	In other words, enables "strict" mode.
1377		1749
1378	Unlike C<use strict>, it is definitely recommended ot keep it off in	1750	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
1379	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1751	>>, it is definitely recommended to keep it off in production. Keeping
1380	developing programs can be very useful, however.	1752	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1753	can be very useful, however.
1381		1754
1382	=item C<PERL_ANYEVENT_MODEL>	1755	=item C<PERL_ANYEVENT_MODEL>
1383		1756
1384	This can be used to specify the event model to be used by AnyEvent, before	1757	This can be used to specify the event model to be used by AnyEvent, before
1385	auto detection and -probing kicks in. It must be a string consisting	1758	auto detection and -probing kicks in. It must be a string consisting
…		…
1428		1801
1429	=item C<PERL_ANYEVENT_MAX_FORKS>	1802	=item C<PERL_ANYEVENT_MAX_FORKS>
1430		1803
1431	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1804	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1432	will create in parallel.	1805	will create in parallel.
		1806
		1807	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1808
		1809	The default value for the C<max_outstanding> parameter for the default DNS
		1810	resolver - this is the maximum number of parallel DNS requests that are
		1811	sent to the DNS server.
		1812
		1813	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1814
		1815	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1816	configuration) in the default resolver. When set to the empty string, no
		1817	default config will be used.
		1818
		1819	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1820
		1821	When neither C<ca_file> nor C<ca_path> was specified during
		1822	L<AnyEvent::TLS> context creation, and either of these environment
		1823	variables exist, they will be used to specify CA certificate locations
		1824	instead of a system-dependent default.
		1825
		1826	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1827
		1828	When these are set to C<1>, then the respective modules are not
		1829	loaded. Mostly good for testing AnyEvent itself.
1433		1830
1434	=back	1831	=back
1435		1832
1436	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1833	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1437		1834
…		…
1682	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	2079	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1683	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	2080	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1684	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	2081	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1685	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	2082	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1686	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	2083	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		2084	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		2085	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1687	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	2086	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1688	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	2087	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1689	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	2088	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1690	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	2089	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1691		2090
…		…
1720	performance becomes really bad with lots of file descriptors (and few of	2119	performance becomes really bad with lots of file descriptors (and few of
1721	them active), of course, but this was not subject of this benchmark.	2120	them active), of course, but this was not subject of this benchmark.
1722		2121
1723	The C<Event> module has a relatively high setup and callback invocation	2122	The C<Event> module has a relatively high setup and callback invocation
1724	cost, but overall scores in on the third place.	2123	cost, but overall scores in on the third place.
		2124
		2125	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2126	when using its pure perl backend.
1725		2127
1726	C<Glib>'s memory usage is quite a bit higher, but it features a	2128	C<Glib>'s memory usage is quite a bit higher, but it features a
1727	faster callback invocation and overall ends up in the same class as	2129	faster callback invocation and overall ends up in the same class as
1728	C<Event>. However, Glib scales extremely badly, doubling the number of	2130	C<Event>. However, Glib scales extremely badly, doubling the number of
1729	watchers increases the processing time by more than a factor of four,	2131	watchers increases the processing time by more than a factor of four,
…		…
1807	it to another server. This includes deleting the old timeout and creating	2209	it to another server. This includes deleting the old timeout and creating
1808	a new one that moves the timeout into the future.	2210	a new one that moves the timeout into the future.
1809		2211
1810	=head3 Results	2212	=head3 Results
1811		2213
1812	name sockets create request	2214	name sockets create request
1813	EV 20000 69.01 11.16	2215	EV 20000 69.01 11.16
1814	Perl 20000 73.32 35.87	2216	Perl 20000 73.32 35.87
		2217	IOAsync 20000 157.00 98.14 epoll
		2218	IOAsync 20000 159.31 616.06 poll
1815	Event 20000 212.62 257.32	2219	Event 20000 212.62 257.32
1816	Glib 20000 651.16 1896.30	2220	Glib 20000 651.16 1896.30
1817	POE 20000 349.67 12317.24 uses POE::Loop::Event	2221	POE 20000 349.67 12317.24 uses POE::Loop::Event
1818		2222
1819	=head3 Discussion	2223	=head3 Discussion
1820		2224
1821	This benchmark I<does> measure scalability and overall performance of the	2225	This benchmark I<does> measure scalability and overall performance of the
1822	particular event loop.	2226	particular event loop.
…		…
1824	EV is again fastest. Since it is using epoll on my system, the setup time	2228	EV is again fastest. Since it is using epoll on my system, the setup time
1825	is relatively high, though.	2229	is relatively high, though.
1826		2230
1827	Perl surprisingly comes second. It is much faster than the C-based event	2231	Perl surprisingly comes second. It is much faster than the C-based event
1828	loops Event and Glib.	2232	loops Event and Glib.
		2233
		2234	IO::Async performs very well when using its epoll backend, and still quite
		2235	good compared to Glib when using its pure perl backend.
1829		2236
1830	Event suffers from high setup time as well (look at its code and you will	2237	Event suffers from high setup time as well (look at its code and you will
1831	understand why). Callback invocation also has a high overhead compared to	2238	understand why). Callback invocation also has a high overhead compared to
1832	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2239	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1833	uses select or poll in basically all documented configurations.	2240	uses select or poll in basically all documented configurations.
…		…
1896	=item * C-based event loops perform very well with small number of	2303	=item * C-based event loops perform very well with small number of
1897	watchers, as the management overhead dominates.	2304	watchers, as the management overhead dominates.
1898		2305
1899	=back	2306	=back
1900		2307
		2308	=head2 THE IO::Lambda BENCHMARK
		2309
		2310	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2311	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2312	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2313	shouldn't come as a surprise to anybody). As such, the benchmark is
		2314	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2315	very optimal. But how would AnyEvent compare when used without the extra
		2316	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2317
		2318	The benchmark itself creates an echo-server, and then, for 500 times,
		2319	connects to the echo server, sends a line, waits for the reply, and then
		2320	creates the next connection. This is a rather bad benchmark, as it doesn't
		2321	test the efficiency of the framework or much non-blocking I/O, but it is a
		2322	benchmark nevertheless.
		2323
		2324	name runtime
		2325	Lambda/select 0.330 sec
		2326	+ optimized 0.122 sec
		2327	Lambda/AnyEvent 0.327 sec
		2328	+ optimized 0.138 sec
		2329	Raw sockets/select 0.077 sec
		2330	POE/select, components 0.662 sec
		2331	POE/select, raw sockets 0.226 sec
		2332	POE/select, optimized 0.404 sec
		2333
		2334	AnyEvent/select/nb 0.085 sec
		2335	AnyEvent/EV/nb 0.068 sec
		2336	+state machine 0.134 sec
		2337
		2338	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2339	benchmarks actually make blocking connects and use 100% blocking I/O,
		2340	defeating the purpose of an event-based solution. All of the newly
		2341	written AnyEvent benchmarks use 100% non-blocking connects (using
		2342	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2343	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2344	generally require a lot more bookkeeping and event handling than blocking
		2345	connects (which involve a single syscall only).
		2346
		2347	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2348	offers similar expressive power as POE and IO::Lambda, using conventional
		2349	Perl syntax. This means that both the echo server and the client are 100%
		2350	non-blocking, further placing it at a disadvantage.
		2351
		2352	As you can see, the AnyEvent + EV combination even beats the
		2353	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2354	backend easily beats IO::Lambda and POE.
		2355
		2356	And even the 100% non-blocking version written using the high-level (and
		2357	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2358	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2359	in a non-blocking way.
		2360
		2361	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2362	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2363	part of the IO::lambda distribution and were used without any changes.
		2364
1901		2365
1902	=head1 SIGNALS	2366	=head1 SIGNALS
1903		2367
1904	AnyEvent currently installs handlers for these signals:	2368	AnyEvent currently installs handlers for these signals:
1905		2369
…		…
1908	=item SIGCHLD	2372	=item SIGCHLD
1909		2373
1910	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2374	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1911	emulation for event loops that do not support them natively. Also, some	2375	emulation for event loops that do not support them natively. Also, some
1912	event loops install a similar handler.	2376	event loops install a similar handler.
		2377
		2378	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2379	AnyEvent will reset it to default, to avoid losing child exit statuses.
1913		2380
1914	=item SIGPIPE	2381	=item SIGPIPE
1915		2382
1916	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2383	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1917	when AnyEvent gets loaded.	2384	when AnyEvent gets loaded.
…		…
1929		2396
1930	=back	2397	=back
1931		2398
1932	=cut	2399	=cut
1933		2400
		2401	undef $SIG{CHLD}
		2402	if $SIG{CHLD} eq 'IGNORE';
		2403
1934	$SIG{PIPE} = sub { }	2404	$SIG{PIPE} = sub { }
1935	unless defined $SIG{PIPE};	2405	unless defined $SIG{PIPE};
		2406
		2407	=head1 RECOMMENDED/OPTIONAL MODULES
		2408
		2409	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2410	it's built-in modules) are required to use it.
		2411
		2412	That does not mean that AnyEvent won't take advantage of some additional
		2413	modules if they are installed.
		2414
		2415	This section epxlains which additional modules will be used, and how they
		2416	affect AnyEvent's operetion.
		2417
		2418	=over 4
		2419
		2420	=item L<Async::Interrupt>
		2421
		2422	This slightly arcane module is used to implement fast signal handling: To
		2423	my knowledge, there is no way to do completely race-free and quick
		2424	signal handling in pure perl. To ensure that signals still get
		2425	delivered, AnyEvent will start an interval timer to wake up perl (and
		2426	catch the signals) with some delay (default is 10 seconds, look for
		2427	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2428
		2429	If this module is available, then it will be used to implement signal
		2430	catching, which means that signals will not be delayed, and the event loop
		2431	will not be interrupted regularly, which is more efficient (And good for
		2432	battery life on laptops).
		2433
		2434	This affects not just the pure-perl event loop, but also other event loops
		2435	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2436
		2437	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2438	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2439	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2440	does nothing for those backends.
		2441
		2442	=item L<EV>
		2443
		2444	This module isn't really "optional", as it is simply one of the backend
		2445	event loops that AnyEvent can use. However, it is simply the best event
		2446	loop available in terms of features, speed and stability: It supports
		2447	the AnyEvent API optimally, implements all the watcher types in XS, does
		2448	automatic timer adjustments even when no monotonic clock is available,
		2449	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2450	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2451	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2452
		2453	=item L<Guard>
		2454
		2455	The guard module, when used, will be used to implement
		2456	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2457	lot less memory), but otherwise doesn't affect guard operation much. It is
		2458	purely used for performance.
		2459
		2460	=item L<JSON> and L<JSON::XS>
		2461
		2462	This module is required when you want to read or write JSON data via
		2463	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2464	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2465
		2466	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2467	installed.
		2468
		2469	=item L<Net::SSLeay>
		2470
		2471	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2472	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2473	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2474
		2475	=item L<Time::HiRes>
		2476
		2477	This module is part of perl since release 5.008. It will be used when the
		2478	chosen event library does not come with a timing source on it's own. The
		2479	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2480	try to use a monotonic clock for timing stability.
		2481
		2482	=back
1936		2483
1937		2484
1938	=head1 FORK	2485	=head1 FORK
1939		2486
1940	Most event libraries are not fork-safe. The ones who are usually are	2487	Most event libraries are not fork-safe. The ones who are usually are
1941	because they rely on inefficient but fork-safe C<select> or C<poll>	2488	because they rely on inefficient but fork-safe C<select> or C<poll>
1942	calls. Only L<EV> is fully fork-aware.	2489	calls. Only L<EV> is fully fork-aware.
1943		2490
1944	If you have to fork, you must either do so I<before> creating your first	2491	If you have to fork, you must either do so I<before> creating your first
1945	watcher OR you must not use AnyEvent at all in the child.	2492	watcher OR you must not use AnyEvent at all in the child OR you must do
		2493	something completely out of the scope of AnyEvent.
1946		2494
1947		2495
1948	=head1 SECURITY CONSIDERATIONS	2496	=head1 SECURITY CONSIDERATIONS
1949		2497
1950	AnyEvent can be forced to load any event model via	2498	AnyEvent can be forced to load any event model via
…		…
1962	use AnyEvent;	2510	use AnyEvent;
1963		2511
1964	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2512	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1965	be used to probe what backend is used and gain other information (which is	2513	be used to probe what backend is used and gain other information (which is
1966	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2514	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1967	$ENV{PERL_ANYEGENT_STRICT}.	2515	$ENV{PERL_ANYEVENT_STRICT}.
		2516
		2517	Note that AnyEvent will remove I<all> environment variables starting with
		2518	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2519	enabled.
1968		2520
1969		2521
1970	=head1 BUGS	2522	=head1 BUGS
1971		2523
1972	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2524	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
…		…
1984	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2536	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1985		2537
1986	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2538	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1987	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2539	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1988	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2540	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1989	L<AnyEvent::Impl::POE>.	2541	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1990		2542
1991	Non-blocking file handles, sockets, TCP clients and	2543	Non-blocking file handles, sockets, TCP clients and
1992	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2544	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1993		2545
1994	Asynchronous DNS: L<AnyEvent::DNS>.	2546	Asynchronous DNS: L<AnyEvent::DNS>.
1995		2547
1996	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2548	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2549	L<Coro::Event>,
1997		2550
1998	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2551	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2552	L<AnyEvent::HTTP>.
1999		2553
2000		2554
2001	=head1 AUTHOR	2555	=head1 AUTHOR
2002		2556
2003	Marc Lehmann <schmorp@schmorp.de>	2557	Marc Lehmann <schmorp@schmorp.de>

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