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Revision 1.205 by root, Sun Apr 19 12:09:46 2009 UTC vs.
Revision 1.259 by root, Tue Jul 28 02:07:18 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
		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	Repository>, at L<http://anyevent.schmorp.de>, for more info.
37		53
38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
39		55
40	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
41	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
…		…
168	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
169		185
170	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	186	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
171	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
172		188
173	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch	189	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
174	for events (AnyEvent might or might not keep a reference to this file	190	for events (AnyEvent might or might not keep a reference to this file
175	handle). Note that only file handles pointing to things for which	191	handle). Note that only file handles pointing to things for which
176	non-blocking operation makes sense are allowed. This includes sockets,	192	non-blocking operation makes sense are allowed. This includes sockets,
177	most character devices, pipes, fifos and so on, but not for example files	193	most character devices, pipes, fifos and so on, but not for example files
178	or block devices.	194	or block devices.
…		…
353	invocation, and callback invocation will be synchronous. Synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
354	that it might take a while until the signal gets handled by the process,	370	that it might take a while until the signal gets handled by the process,
355	but it is guaranteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
356		372
357	The main advantage of using these watchers is that you can share a signal	373	The main advantage of using these watchers is that you can share a signal
358	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
359		376
360	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
361	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
362		380
363	Example: exit on SIGINT	381	Example: exit on SIGINT
364		382
365	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
366		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$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.
		400
367	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
368		402
369	You can also watch on a child process exit and catch its exit status.	403	You can also watch on a child process exit and catch its exit status.
370		404
371	The child process is specified by the C<pid> argument (if set to C<0>, it	405	The child process is specified by the C<pid> argument (one some backends,
372	watches for any child process exit). The watcher will triggered only when	406	using C<0> watches for any child process exit, on others this will
373	the child process has finished and an exit status is available, not on	407	croak). The watcher will be triggered only when the child process has
374	any trace events (stopped/continued).	408	finished and an exit status is available, not on any trace events
		409	(stopped/continued).
375		410
376	The callback will be called with the pid and exit status (as returned by	411	The callback will be called with the pid and exit status (as returned by
377	waitpid), so unlike other watcher types, you I<can> rely on child watcher	412	waitpid), so unlike other watcher types, you I<can> rely on child watcher
378	callback arguments.	413	callback arguments.
379		414
…		…
384		419
385	There is a slight catch to child watchers, however: you usually start them	420	There is a slight catch to child watchers, however: you usually start them
386	I<after> the child process was created, and this means the process could	421	I<after> the child process was created, and this means the process could
387	have exited already (and no SIGCHLD will be sent anymore).	422	have exited already (and no SIGCHLD will be sent anymore).
388		423
389	Not all event models handle this correctly (POE doesn't), but even for	424	Not all event models handle this correctly (neither POE nor IO::Async do,
		425	see their AnyEvent::Impl manpages for details), but even for event models
390	event models that I<do> handle this correctly, they usually need to be	426	that I<do> handle this correctly, they usually need to be loaded before
391	loaded before the process exits (i.e. before you fork in the first place).	427	the process exits (i.e. before you fork in the first place). AnyEvent's
		428	pure perl event loop handles all cases correctly regardless of when you
		429	start the watcher.
392		430
393	This means you cannot create a child watcher as the very first thing in an	431	This means you cannot create a child watcher as the very first
394	AnyEvent program, you I<have> to create at least one watcher before you	432	thing in an AnyEvent program, you I<have> to create at least one
395	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	433	watcher before you C<fork> the child (alternatively, you can call
		434	C<AnyEvent::detect>).
		435
		436	As most event loops do not support waiting for child events, they will be
		437	emulated by AnyEvent in most cases, in which the latency and race problems
		438	mentioned in the description of signal watchers apply.
396		439
397	Example: fork a process and wait for it	440	Example: fork a process and wait for it
398		441
399	my $done = AnyEvent->condvar;	442	my $done = AnyEvent->condvar;
400		443
…		…
410	);	453	);
411		454
412	# do something else, then wait for process exit	455	# do something else, then wait for process exit
413	$done->recv;	456	$done->recv;
414		457
		458	=head2 IDLE WATCHERS
		459
		460	Sometimes there is a need to do something, but it is not so important
		461	to do it instantly, but only when there is nothing better to do. This
		462	"nothing better to do" is usually defined to be "no other events need
		463	attention by the event loop".
		464
		465	Idle watchers ideally get invoked when the event loop has nothing
		466	better to do, just before it would block the process to wait for new
		467	events. Instead of blocking, the idle watcher is invoked.
		468
		469	Most event loops unfortunately do not really support idle watchers (only
		470	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		471	will simply call the callback "from time to time".
		472
		473	Example: read lines from STDIN, but only process them when the
		474	program is otherwise idle:
		475
		476	my @lines; # read data
		477	my $idle_w;
		478	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		479	push @lines, scalar <STDIN>;
		480
		481	# start an idle watcher, if not already done
		482	$idle_w ||= AnyEvent->idle (cb => sub {
		483	# handle only one line, when there are lines left
		484	if (my $line = shift @lines) {
		485	print "handled when idle: $line";
		486	} else {
		487	# otherwise disable the idle watcher again
		488	undef $idle_w;
		489	}
		490	});
		491	});
		492
415	=head2 CONDITION VARIABLES	493	=head2 CONDITION VARIABLES
416		494
417	If you are familiar with some event loops you will know that all of them	495	If you are familiar with some event loops you will know that all of them
418	require you to run some blocking "loop", "run" or similar function that	496	require you to run some blocking "loop", "run" or similar function that
419	will actively watch for new events and call your callbacks.	497	will actively watch for new events and call your callbacks.
420		498
421	AnyEvent is different, it expects somebody else to run the event loop and	499	AnyEvent is slightly different: it expects somebody else to run the event
422	will only block when necessary (usually when told by the user).	500	loop and will only block when necessary (usually when told by the user).
423		501
424	The instrument to do that is called a "condition variable", so called	502	The instrument to do that is called a "condition variable", so called
425	because they represent a condition that must become true.	503	because they represent a condition that must become true.
426		504
		505	Now is probably a good time to look at the examples further below.
		506
427	Condition variables can be created by calling the C<< AnyEvent->condvar	507	Condition variables can be created by calling the C<< AnyEvent->condvar
428	>> method, usually without arguments. The only argument pair allowed is	508	>> method, usually without arguments. The only argument pair allowed is
429
430	C<cb>, which specifies a callback to be called when the condition variable	509	C<cb>, which specifies a callback to be called when the condition variable
431	becomes true, with the condition variable as the first argument (but not	510	becomes true, with the condition variable as the first argument (but not
432	the results).	511	the results).
433		512
434	After creation, the condition variable is "false" until it becomes "true"	513	After creation, the condition variable is "false" until it becomes "true"
…		…
439	Condition variables are similar to callbacks, except that you can	518	Condition variables are similar to callbacks, except that you can
440	optionally wait for them. They can also be called merge points - points	519	optionally wait for them. They can also be called merge points - points
441	in time where multiple outstanding events have been processed. And yet	520	in time where multiple outstanding events have been processed. And yet
442	another way to call them is transactions - each condition variable can be	521	another way to call them is transactions - each condition variable can be
443	used to represent a transaction, which finishes at some point and delivers	522	used to represent a transaction, which finishes at some point and delivers
444	a result.	523	a result. And yet some people know them as "futures" - a promise to
		524	compute/deliver something that you can wait for.
445		525
446	Condition variables are very useful to signal that something has finished,	526	Condition variables are very useful to signal that something has finished,
447	for example, if you write a module that does asynchronous http requests,	527	for example, if you write a module that does asynchronous http requests,
448	then a condition variable would be the ideal candidate to signal the	528	then a condition variable would be the ideal candidate to signal the
449	availability of results. The user can either act when the callback is	529	availability of results. The user can either act when the callback is
…		…
483	after => 1,	563	after => 1,
484	cb => sub { $result_ready->send },	564	cb => sub { $result_ready->send },
485	);	565	);
486		566
487	# this "blocks" (while handling events) till the callback	567	# this "blocks" (while handling events) till the callback
488	# calls send	568	# calls -<send
489	$result_ready->recv;	569	$result_ready->recv;
490		570
491	Example: wait for a timer, but take advantage of the fact that	571	Example: wait for a timer, but take advantage of the fact that condition
492	condition variables are also code references.	572	variables are also callable directly.
493		573
494	my $done = AnyEvent->condvar;	574	my $done = AnyEvent->condvar;
495	my $delay = AnyEvent->timer (after => 5, cb => $done);	575	my $delay = AnyEvent->timer (after => 5, cb => $done);
496	$done->recv;	576	$done->recv;
497		577
…		…
503		583
504	...	584	...
505		585
506	my @info = $couchdb->info->recv;	586	my @info = $couchdb->info->recv;
507		587
508	And this is how you would just ste a callback to be called whenever the	588	And this is how you would just set a callback to be called whenever the
509	results are available:	589	results are available:
510		590
511	$couchdb->info->cb (sub {	591	$couchdb->info->cb (sub {
512	my @info = $_[0]->recv;	592	my @info = $_[0]->recv;
513	});	593	});
…		…
531	immediately from within send.	611	immediately from within send.
532		612
533	Any arguments passed to the C<send> call will be returned by all	613	Any arguments passed to the C<send> call will be returned by all
534	future C<< ->recv >> calls.	614	future C<< ->recv >> calls.
535		615
536	Condition variables are overloaded so one can call them directly	616	Condition variables are overloaded so one can call them directly (as if
537	(as a code reference). Calling them directly is the same as calling	617	they were a code reference). Calling them directly is the same as calling
538	C<send>. Note, however, that many C-based event loops do not handle	618	C<send>.
539	overloading, so as tempting as it may be, passing a condition variable
540	instead of a callback does not work. Both the pure perl and EV loops
541	support overloading, however, as well as all functions that use perl to
542	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
543	example).
544		619
545	=item $cv->croak ($error)	620	=item $cv->croak ($error)
546		621
547	Similar to send, but causes all call's to C<< ->recv >> to invoke	622	Similar to send, but causes all call's to C<< ->recv >> to invoke
548	C<Carp::croak> with the given error message/object/scalar.	623	C<Carp::croak> with the given error message/object/scalar.
549		624
550	This can be used to signal any errors to the condition variable	625	This can be used to signal any errors to the condition variable
551	user/consumer.	626	user/consumer. Doing it this way instead of calling C<croak> directly
		627	delays the error detetcion, but has the overwhelmign advantage that it
		628	diagnoses the error at the place where the result is expected, and not
		629	deep in some event clalback without connection to the actual code causing
		630	the problem.
552		631
553	=item $cv->begin ([group callback])	632	=item $cv->begin ([group callback])
554		633
555	=item $cv->end	634	=item $cv->end
556
557	These two methods are EXPERIMENTAL and MIGHT CHANGE.
558		635
559	These two methods can be used to combine many transactions/events into	636	These two methods can be used to combine many transactions/events into
560	one. For example, a function that pings many hosts in parallel might want	637	one. For example, a function that pings many hosts in parallel might want
561	to use a condition variable for the whole process.	638	to use a condition variable for the whole process.
562		639
…		…
564	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	641	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
565	>>, the (last) callback passed to C<begin> will be executed. That callback	642	>>, the (last) callback passed to C<begin> will be executed. That callback
566	is I<supposed> to call C<< ->send >>, but that is not required. If no	643	is I<supposed> to call C<< ->send >>, but that is not required. If no
567	callback was set, C<send> will be called without any arguments.	644	callback was set, C<send> will be called without any arguments.
568		645
569	Let's clarify this with the ping example:	646	You can think of C<< $cv->send >> giving you an OR condition (one call
		647	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		648	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		649
		650	Let's start with a simple example: you have two I/O watchers (for example,
		651	STDOUT and STDERR for a program), and you want to wait for both streams to
		652	close before activating a condvar:
		653
		654	my $cv = AnyEvent->condvar;
		655
		656	$cv->begin; # first watcher
		657	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		658	defined sysread $fh1, my $buf, 4096
		659	or $cv->end;
		660	});
		661
		662	$cv->begin; # second watcher
		663	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		664	defined sysread $fh2, my $buf, 4096
		665	or $cv->end;
		666	});
		667
		668	$cv->recv;
		669
		670	This works because for every event source (EOF on file handle), there is
		671	one call to C<begin>, so the condvar waits for all calls to C<end> before
		672	sending.
		673
		674	The ping example mentioned above is slightly more complicated, as the
		675	there are results to be passwd back, and the number of tasks that are
		676	begung can potentially be zero:
570		677
571	my $cv = AnyEvent->condvar;	678	my $cv = AnyEvent->condvar;
572		679
573	my %result;	680	my %result;
574	$cv->begin (sub { $cv->send (\%result) });	681	$cv->begin (sub { $cv->send (\%result) });
…		…
594	loop, which serves two important purposes: first, it sets the callback	701	loop, which serves two important purposes: first, it sets the callback
595	to be called once the counter reaches C<0>, and second, it ensures that	702	to be called once the counter reaches C<0>, and second, it ensures that
596	C<send> is called even when C<no> hosts are being pinged (the loop	703	C<send> is called even when C<no> hosts are being pinged (the loop
597	doesn't execute once).	704	doesn't execute once).
598		705
599	This is the general pattern when you "fan out" into multiple subrequests:	706	This is the general pattern when you "fan out" into multiple (but
600	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	707	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
601	is called at least once, and then, for each subrequest you start, call	708	the callback and ensure C<end> is called at least once, and then, for each
602	C<begin> and for each subrequest you finish, call C<end>.	709	subrequest you start, call C<begin> and for each subrequest you finish,
		710	call C<end>.
603		711
604	=back	712	=back
605		713
606	=head3 METHODS FOR CONSUMERS	714	=head3 METHODS FOR CONSUMERS
607		715
…		…
623	function will call C<croak>.	731	function will call C<croak>.
624		732
625	In list context, all parameters passed to C<send> will be returned,	733	In list context, all parameters passed to C<send> will be returned,
626	in scalar context only the first one will be returned.	734	in scalar context only the first one will be returned.
627		735
		736	Note that doing a blocking wait in a callback is not supported by any
		737	event loop, that is, recursive invocation of a blocking C<< ->recv
		738	>> is not allowed, and the C<recv> call will C<croak> if such a
		739	condition is detected. This condition can be slightly loosened by using
		740	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		741	any thread that doesn't run the event loop itself.
		742
628	Not all event models support a blocking wait - some die in that case	743	Not all event models support a blocking wait - some die in that case
629	(programs might want to do that to stay interactive), so I<if you are	744	(programs might want to do that to stay interactive), so I<if you are
630	using this from a module, never require a blocking wait>, but let the	745	using this from a module, never require a blocking wait>. Instead, let the
631	caller decide whether the call will block or not (for example, by coupling	746	caller decide whether the call will block or not (for example, by coupling
632	condition variables with some kind of request results and supporting	747	condition variables with some kind of request results and supporting
633	callbacks so the caller knows that getting the result will not block,	748	callbacks so the caller knows that getting the result will not block,
634	while still supporting blocking waits if the caller so desires).	749	while still supporting blocking waits if the caller so desires).
635		750
636	Another reason I<never> to C<< ->recv >> in a module is that you cannot
637	sensibly have two C<< ->recv >>'s in parallel, as that would require
638	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
639	can supply.
640
641	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
642	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
643	versions and also integrates coroutines into AnyEvent, making blocking
644	C<< ->recv >> calls perfectly safe as long as they are done from another
645	coroutine (one that doesn't run the event loop).
646
647	You can ensure that C<< -recv >> never blocks by setting a callback and	751	You can ensure that C<< -recv >> never blocks by setting a callback and
648	only calling C<< ->recv >> from within that callback (or at a later	752	only calling C<< ->recv >> from within that callback (or at a later
649	time). This will work even when the event loop does not support blocking	753	time). This will work even when the event loop does not support blocking
650	waits otherwise.	754	waits otherwise.
651		755
…		…
664	variable itself. Calling C<recv> inside the callback or at any later time	768	variable itself. Calling C<recv> inside the callback or at any later time
665	is guaranteed not to block.	769	is guaranteed not to block.
666		770
667	=back	771	=back
668		772
		773	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		774
		775	The available backend classes are (every class has its own manpage):
		776
		777	=over 4
		778
		779	=item Backends that are autoprobed when no other event loop can be found.
		780
		781	EV is the preferred backend when no other event loop seems to be in
		782	use. If EV is not installed, then AnyEvent will try Event, and, failing
		783	that, will fall back to its own pure-perl implementation, which is
		784	available everywhere as it comes with AnyEvent itself.
		785
		786	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		787	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		788	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		789
		790	=item Backends that are transparently being picked up when they are used.
		791
		792	These will be used when they are currently loaded when the first watcher
		793	is created, in which case it is assumed that the application is using
		794	them. This means that AnyEvent will automatically pick the right backend
		795	when the main program loads an event module before anything starts to
		796	create watchers. Nothing special needs to be done by the main program.
		797
		798	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		799	AnyEvent::Impl::Tk based on Tk, very broken.
		800	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		801	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		802	AnyEvent::Impl::Irssi used when running within irssi.
		803
		804	=item Backends with special needs.
		805
		806	Qt requires the Qt::Application to be instantiated first, but will
		807	otherwise be picked up automatically. As long as the main program
		808	instantiates the application before any AnyEvent watchers are created,
		809	everything should just work.
		810
		811	AnyEvent::Impl::Qt based on Qt.
		812
		813	Support for IO::Async can only be partial, as it is too broken and
		814	architecturally limited to even support the AnyEvent API. It also
		815	is the only event loop that needs the loop to be set explicitly, so
		816	it can only be used by a main program knowing about AnyEvent. See
		817	L<AnyEvent::Impl::Async> for the gory details.
		818
		819	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		820
		821	=item Event loops that are indirectly supported via other backends.
		822
		823	Some event loops can be supported via other modules:
		824
		825	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		826
		827	B<WxWidgets> has no support for watching file handles. However, you can
		828	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		829	polls 20 times per second, which was considered to be too horrible to even
		830	consider for AnyEvent.
		831
		832	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		833	backend, so it can be supported through POE.
		834
		835	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		836	load L<POE> when detecting them, in the hope that POE will pick them up,
		837	in which case everything will be automatic.
		838
		839	=back
		840
669	=head1 GLOBAL VARIABLES AND FUNCTIONS	841	=head1 GLOBAL VARIABLES AND FUNCTIONS
670		842
		843	These are not normally required to use AnyEvent, but can be useful to
		844	write AnyEvent extension modules.
		845
671	=over 4	846	=over 4
672		847
673	=item $AnyEvent::MODEL	848	=item $AnyEvent::MODEL
674		849
675	Contains C<undef> until the first watcher is being created. Then it	850	Contains C<undef> until the first watcher is being created, before the
		851	backend has been autodetected.
		852
676	contains the event model that is being used, which is the name of the	853	Afterwards it contains the event model that is being used, which is the
677	Perl class implementing the model. This class is usually one of the	854	name of the Perl class implementing the model. This class is usually one
678	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	855	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
679	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	856	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
680		857	will be C<urxvt::anyevent>).
681	The known classes so far are:
682
683	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
684	AnyEvent::Impl::Event based on Event, second best choice.
685	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
686	AnyEvent::Impl::Glib based on Glib, third-best choice.
687	AnyEvent::Impl::Tk based on Tk, very bad choice.
688	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
689	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
690	AnyEvent::Impl::POE based on POE, not generic enough for full support.
691
692	There is no support for WxWidgets, as WxWidgets has no support for
693	watching file handles. However, you can use WxWidgets through the
694	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
695	second, which was considered to be too horrible to even consider for
696	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
697	it's adaptor.
698
699	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
700	autodetecting them.
701		858
702	=item AnyEvent::detect	859	=item AnyEvent::detect
703		860
704	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	861	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
705	if necessary. You should only call this function right before you would	862	if necessary. You should only call this function right before you would
706	have created an AnyEvent watcher anyway, that is, as late as possible at	863	have created an AnyEvent watcher anyway, that is, as late as possible at
707	runtime.	864	runtime, and not e.g. while initialising of your module.
		865
		866	If you need to do some initialisation before AnyEvent watchers are
		867	created, use C<post_detect>.
708		868
709	=item $guard = AnyEvent::post_detect { BLOCK }	869	=item $guard = AnyEvent::post_detect { BLOCK }
710		870
711	Arranges for the code block to be executed as soon as the event model is	871	Arranges for the code block to be executed as soon as the event model is
712	autodetected (or immediately if this has already happened).	872	autodetected (or immediately if this has already happened).
713		873
		874	The block will be executed I<after> the actual backend has been detected
		875	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		876	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		877	other initialisations - see the sources of L<AnyEvent::Strict> or
		878	L<AnyEvent::AIO> to see how this is used.
		879
		880	The most common usage is to create some global watchers, without forcing
		881	event module detection too early, for example, L<AnyEvent::AIO> creates
		882	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		883	avoid autodetecting the event module at load time.
		884
714	If called in scalar or list context, then it creates and returns an object	885	If called in scalar or list context, then it creates and returns an object
715	that automatically removes the callback again when it is destroyed. See	886	that automatically removes the callback again when it is destroyed (or
		887	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
716	L<Coro::BDB> for a case where this is useful.	888	a case where this is useful.
		889
		890	Example: Create a watcher for the IO::AIO module and store it in
		891	C<$WATCHER>. Only do so after the event loop is initialised, though.
		892
		893	our WATCHER;
		894
		895	my $guard = AnyEvent::post_detect {
		896	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		897	};
		898
		899	# the ||= is important in case post_detect immediately runs the block,
		900	# as to not clobber the newly-created watcher. assigning both watcher and
		901	# post_detect guard to the same variable has the advantage of users being
		902	# able to just C<undef $WATCHER> if the watcher causes them grief.
		903
		904	$WATCHER ||= $guard;
717		905
718	=item @AnyEvent::post_detect	906	=item @AnyEvent::post_detect
719		907
720	If there are any code references in this array (you can C<push> to it	908	If there are any code references in this array (you can C<push> to it
721	before or after loading AnyEvent), then they will called directly after	909	before or after loading AnyEvent), then they will called directly after
722	the event loop has been chosen.	910	the event loop has been chosen.
723		911
724	You should check C<$AnyEvent::MODEL> before adding to this array, though:	912	You should check C<$AnyEvent::MODEL> before adding to this array, though:
725	if it contains a true value then the event loop has already been detected,	913	if it is defined then the event loop has already been detected, and the
726	and the array will be ignored.	914	array will be ignored.
727		915
728	Best use C<AnyEvent::post_detect { BLOCK }> instead.	916	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		917	it,as it takes care of these details.
		918
		919	This variable is mainly useful for modules that can do something useful
		920	when AnyEvent is used and thus want to know when it is initialised, but do
		921	not need to even load it by default. This array provides the means to hook
		922	into AnyEvent passively, without loading it.
729		923
730	=back	924	=back
731		925
732	=head1 WHAT TO DO IN A MODULE	926	=head1 WHAT TO DO IN A MODULE
733		927
…		…
788		982
789		983
790	=head1 OTHER MODULES	984	=head1 OTHER MODULES
791		985
792	The following is a non-exhaustive list of additional modules that use	986	The following is a non-exhaustive list of additional modules that use
793	AnyEvent and can therefore be mixed easily with other AnyEvent modules	987	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
794	in the same program. Some of the modules come with AnyEvent, some are	988	modules and other event loops in the same program. Some of the modules
795	available via CPAN.	989	come with AnyEvent, most are available via CPAN.
796		990
797	=over 4	991	=over 4
798		992
799	=item L<AnyEvent::Util>	993	=item L<AnyEvent::Util>
800		994
…		…
809		1003
810	=item L<AnyEvent::Handle>	1004	=item L<AnyEvent::Handle>
811		1005
812	Provide read and write buffers, manages watchers for reads and writes,	1006	Provide read and write buffers, manages watchers for reads and writes,
813	supports raw and formatted I/O, I/O queued and fully transparent and	1007	supports raw and formatted I/O, I/O queued and fully transparent and
814	non-blocking SSL/TLS.	1008	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
815		1009
816	=item L<AnyEvent::DNS>	1010	=item L<AnyEvent::DNS>
817		1011
818	Provides rich asynchronous DNS resolver capabilities.	1012	Provides rich asynchronous DNS resolver capabilities.
819		1013
…		…
847		1041
848	=item L<AnyEvent::GPSD>	1042	=item L<AnyEvent::GPSD>
849		1043
850	A non-blocking interface to gpsd, a daemon delivering GPS information.	1044	A non-blocking interface to gpsd, a daemon delivering GPS information.
851		1045
		1046	=item L<AnyEvent::IRC>
		1047
		1048	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1049
		1050	=item L<AnyEvent::XMPP>
		1051
		1052	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1053	Net::XMPP2>.
		1054
852	=item L<AnyEvent::IGS>	1055	=item L<AnyEvent::IGS>
853		1056
854	A non-blocking interface to the Internet Go Server protocol (used by	1057	A non-blocking interface to the Internet Go Server protocol (used by
855	L<App::IGS>).	1058	L<App::IGS>).
856		1059
857	=item L<AnyEvent::IRC>
858
859	AnyEvent based IRC client module family (replacing the older Net::IRC3).
860
861	=item L<Net::XMPP2>
862
863	AnyEvent based XMPP (Jabber protocol) module family.
864
865	=item L<Net::FCP>	1060	=item L<Net::FCP>
866		1061
867	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1062	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
868	of AnyEvent.	1063	of AnyEvent.
869		1064
…		…
873		1068
874	=item L<Coro>	1069	=item L<Coro>
875		1070
876	Has special support for AnyEvent via L<Coro::AnyEvent>.	1071	Has special support for AnyEvent via L<Coro::AnyEvent>.
877		1072
878	=item L<IO::Lambda>
879
880	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
881
882	=back	1073	=back
883		1074
884	=cut	1075	=cut
885		1076
886	package AnyEvent;	1077	package AnyEvent;
887		1078
		1079	# basically a tuned-down version of common::sense
		1080	sub common_sense {
888	no warnings;	1081	# no warnings
		1082	${^WARNING_BITS} ^= ${^WARNING_BITS};
889	use strict qw(vars subs);	1083	# use strict vars subs
		1084	$^H |= 0x00000600;
		1085	}
890		1086
		1087	BEGIN { AnyEvent::common_sense }
		1088
891	use Carp;	1089	use Carp ();
892		1090
893	our $VERSION = 4.351;	1091	our $VERSION = 4.88;
894	our $MODEL;	1092	our $MODEL;
895		1093
896	our $AUTOLOAD;	1094	our $AUTOLOAD;
897	our @ISA;	1095	our @ISA;
898		1096
899	our @REGISTRY;	1097	our @REGISTRY;
900		1098
901	our $WIN32;	1099	our $WIN32;
902		1100
		1101	our $VERBOSE;
		1102
903	BEGIN {	1103	BEGIN {
904	my $win32 = ! ! ($^O =~ /mswin32/i);	1104	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
905	eval "sub WIN32(){ $win32 }";	1105	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
906	}
907		1106
		1107	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1108	if ${^TAINT};
		1109
908	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1110	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1111
		1112	}
		1113
		1114	our $MAX_SIGNAL_LATENCY = 10;
909		1115
910	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1116	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
911		1117
912	{	1118	{
913	my $idx;	1119	my $idx;
…		…
915	for reverse split /\s*,\s*/,	1121	for reverse split /\s*,\s*/,
916	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1122	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
917	}	1123	}
918		1124
919	my @models = (	1125	my @models = (
920	[EV:: => AnyEvent::Impl::EV::],	1126	[EV:: => AnyEvent::Impl::EV:: , 1],
921	[Event:: => AnyEvent::Impl::Event::],	1127	[Event:: => AnyEvent::Impl::Event::, 1],
922	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1128	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
923	# everything below here will not be autoprobed	1129	# everything below here will not (normally) be autoprobed
924	# as the pureperl backend should work everywhere	1130	# as the pureperl backend should work everywhere
925	# and is usually faster	1131	# and is usually faster
		1132	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1133	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1134	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
926	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1135	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
927	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
928	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
929	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1136	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
930	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1137	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
931	[Wx:: => AnyEvent::Impl::POE::],	1138	[Wx:: => AnyEvent::Impl::POE::],
932	[Prima:: => AnyEvent::Impl::POE::],	1139	[Prima:: => AnyEvent::Impl::POE::],
		1140	# IO::Async is just too broken - we would need workarounds for its
		1141	# byzantine signal and broken child handling, among others.
		1142	# IO::Async is rather hard to detect, as it doesn't have any
		1143	# obvious default class.
		1144	# [0, IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1145	# [0, IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1146	# [0, IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
933	);	1147	);
934		1148
935	our %method = map +($_ => 1),	1149	our %method = map +($_ => 1),
936	qw(io timer time now now_update signal child condvar one_event DESTROY);	1150	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
937		1151
938	our @post_detect;	1152	our @post_detect;
939		1153
940	sub post_detect(&) {	1154	sub post_detect(&) {
941	my ($cb) = @_;	1155	my ($cb) = @_;
942		1156
943	if ($MODEL) {	1157	if ($MODEL) {
944	$cb->();	1158	$cb->();
945		1159
946	1	1160	undef
947	} else {	1161	} else {
948	push @post_detect, $cb;	1162	push @post_detect, $cb;
949		1163
950	defined wantarray	1164	defined wantarray
951	? bless \$cb, "AnyEvent::Util::PostDetect"	1165	? bless \$cb, "AnyEvent::Util::postdetect"
952	: ()	1166	: ()
953	}	1167	}
954	}	1168	}
955		1169
956	sub AnyEvent::Util::PostDetect::DESTROY {	1170	sub AnyEvent::Util::postdetect::DESTROY {
957	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1171	@post_detect = grep $_ != ${$_[0]}, @post_detect;
958	}	1172	}
959		1173
960	sub detect() {	1174	sub detect() {
961	unless ($MODEL) {	1175	unless ($MODEL) {
962	no strict 'refs';
963	local $SIG{__DIE__};	1176	local $SIG{__DIE__};
964		1177
965	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1178	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
966	my $model = "AnyEvent::Impl::$1";	1179	my $model = "AnyEvent::Impl::$1";
967	if (eval "require $model") {	1180	if (eval "require $model") {
968	$MODEL = $model;	1181	$MODEL = $model;
969	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1182	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
970	} else {	1183	} else {
971	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1184	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
972	}	1185	}
973	}	1186	}
974		1187
975	# check for already loaded models	1188	# check for already loaded models
976	unless ($MODEL) {	1189	unless ($MODEL) {
977	for (@REGISTRY, @models) {	1190	for (@REGISTRY, @models) {
978	my ($package, $model) = @$_;	1191	my ($package, $model) = @$_;
979	if (${"$package\::VERSION"} > 0) {	1192	if (${"$package\::VERSION"} > 0) {
980	if (eval "require $model") {	1193	if (eval "require $model") {
981	$MODEL = $model;	1194	$MODEL = $model;
982	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1195	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
983	last;	1196	last;
984	}	1197	}
985	}	1198	}
986	}	1199	}
987		1200
988	unless ($MODEL) {	1201	unless ($MODEL) {
989	# try to load a model	1202	# try to autoload a model
990
991	for (@REGISTRY, @models) {	1203	for (@REGISTRY, @models) {
992	my ($package, $model) = @$_;	1204	my ($package, $model, $autoload) = @$_;
		1205	if (
		1206	$autoload
993	if (eval "require $package"	1207	and eval "require $package"
994	and ${"$package\::VERSION"} > 0	1208	and ${"$package\::VERSION"} > 0
995	and eval "require $model") {	1209	and eval "require $model"
		1210	) {
996	$MODEL = $model;	1211	$MODEL = $model;
997	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1212	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
998	last;	1213	last;
999	}	1214	}
1000	}	1215	}
1001		1216
1002	$MODEL	1217	$MODEL
…		…
1018		1233
1019	sub AUTOLOAD {	1234	sub AUTOLOAD {
1020	(my $func = $AUTOLOAD) =~ s/.*://;	1235	(my $func = $AUTOLOAD) =~ s/.*://;
1021		1236
1022	$method{$func}	1237	$method{$func}
1023	or croak "$func: not a valid method for AnyEvent objects";	1238	or Carp::croak "$func: not a valid method for AnyEvent objects";
1024		1239
1025	detect unless $MODEL;	1240	detect unless $MODEL;
1026		1241
1027	my $class = shift;	1242	my $class = shift;
1028	$class->$func (@_);	1243	$class->$func (@_);
1029	}	1244	}
1030		1245
1031	# utility function to dup a filehandle. this is used by many backends	1246	# utility function to dup a filehandle. this is used by many backends
1032	# to support binding more than one watcher per filehandle (they usually	1247	# to support binding more than one watcher per filehandle (they usually
1033	# allow only one watcher per fd, so we dup it to get a different one).	1248	# allow only one watcher per fd, so we dup it to get a different one).
1034	sub _dupfh($$$$) {	1249	sub _dupfh($$;$$) {
1035	my ($poll, $fh, $r, $w) = @_;	1250	my ($poll, $fh, $r, $w) = @_;
1036		1251
1037	# cygwin requires the fh mode to be matching, unix doesn't	1252	# cygwin requires the fh mode to be matching, unix doesn't
1038	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1253	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1039	: $poll eq "w" ? ($w, ">")
1040	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1041		1254
1042	open my $fh2, "$mode&" . fileno $fh	1255	open my $fh2, $mode, $fh
1043	or die "cannot dup() filehandle: $!,";	1256	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1044		1257
1045	# we assume CLOEXEC is already set by perl in all important cases	1258	# we assume CLOEXEC is already set by perl in all important cases
1046		1259
1047	($fh2, $rw)	1260	($fh2, $rw)
1048	}	1261	}
1049		1262
1050	package AnyEvent::Base;	1263	package AnyEvent::Base;
1051		1264
1052	# default implementations for many methods	1265	# default implementations for many methods
1053		1266
1054	BEGIN {	1267	sub _time {
		1268	# probe for availability of Time::HiRes
1055	if (eval "use Time::HiRes (); time (); 1") {	1269	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1270	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1056	*_time = \&Time::HiRes::time;	1271	*_time = \&Time::HiRes::time;
1057	# if (eval "use POSIX (); (POSIX::times())...	1272	# if (eval "use POSIX (); (POSIX::times())...
1058	} else {	1273	} else {
		1274	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1059	*_time = sub { time }; # epic fail	1275	*_time = sub { time }; # epic fail
1060	}	1276	}
		1277
		1278	&_time
1061	}	1279	}
1062		1280
1063	sub time { _time }	1281	sub time { _time }
1064	sub now { _time }	1282	sub now { _time }
1065	sub now_update { }	1283	sub now_update { }
1066		1284
1067	# default implementation for ->condvar	1285	# default implementation for ->condvar
1068		1286
1069	sub condvar {	1287	sub condvar {
1070	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1288	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1071	}	1289	}
1072		1290
1073	# default implementation for ->signal	1291	# default implementation for ->signal
1074		1292
		1293	our $HAVE_ASYNC_INTERRUPT;
1075	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1294	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1295	our (%SIG_ASY, %SIG_ASY_W);
		1296	our ($SIG_COUNT, $SIG_TW);
1076		1297
1077	sub _signal_exec {	1298	sub _signal_exec {
		1299	$HAVE_ASYNC_INTERRUPT
		1300	? $SIGPIPE_R->drain
1078	sysread $SIGPIPE_R, my $dummy, 4;	1301	: sysread $SIGPIPE_R, my $dummy, 9;
1079		1302
1080	while (%SIG_EV) {	1303	while (%SIG_EV) {
1081	for (keys %SIG_EV) {	1304	for (keys %SIG_EV) {
1082	delete $SIG_EV{$_};	1305	delete $SIG_EV{$_};
1083	$_->() for values %{ $SIG_CB{$_} || {} };	1306	$_->() for values %{ $SIG_CB{$_} || {} };
1084	}	1307	}
1085	}	1308	}
1086	}	1309	}
1087		1310
		1311	# install a dumym wakeupw atcher to reduce signal catching latency
		1312	sub _sig_add() {
		1313	unless ($SIG_COUNT++) {
		1314	# try to align timer on a full-second boundary, if possible
		1315	my $NOW = AnyEvent->now;
		1316
		1317	$SIG_TW = AnyEvent->timer (
		1318	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1319	interval => $MAX_SIGNAL_LATENCY,
		1320	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1321	);
		1322	}
		1323	}
		1324
		1325	sub _sig_del {
		1326	undef $SIG_TW
		1327	unless --$SIG_COUNT;
		1328	}
		1329
		1330	sub _signal {
		1331	my (undef, %arg) = @_;
		1332
		1333	my $signal = uc $arg{signal}
		1334	or Carp::croak "required option 'signal' is missing";
		1335
		1336	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1337
		1338	if ($HAVE_ASYNC_INTERRUPT) {
		1339	# async::interrupt
		1340
		1341	$SIG_ASY{$signal} ||= do {
		1342	my $asy = new Async::Interrupt
		1343	cb => sub { undef $SIG_EV{$signal} },
		1344	signal => $signal,
		1345	pipe => [$SIGPIPE_R->filenos],
		1346	;
		1347	$asy->pipe_autodrain (0);
		1348
		1349	$asy
		1350	};
		1351
		1352	} else {
		1353	# pure perl
		1354
		1355	$SIG{$signal} ||= sub {
		1356	local $!;
		1357	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1358	undef $SIG_EV{$signal};
		1359	};
		1360
		1361	# can't do signal processing without introducing races in pure perl,
		1362	# so limit the signal latency.
		1363	_sig_add;
		1364	}
		1365
		1366	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1367	}
		1368
1088	sub signal {	1369	sub signal {
1089	my (undef, %arg) = @_;	1370	# probe for availability of Async::Interrupt
		1371	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1372	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1090		1373
1091	unless ($SIGPIPE_R) {	1374	$HAVE_ASYNC_INTERRUPT = 1;
		1375	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1376	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1377
		1378	} else {
		1379	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1380
1092	require Fcntl;	1381	require Fcntl;
1093		1382
1094	if (AnyEvent::WIN32) {	1383	if (AnyEvent::WIN32) {
1095	require AnyEvent::Util;	1384	require AnyEvent::Util;
1096		1385
…		…
1099	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case	1388	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1100	} else {	1389	} else {
1101	pipe $SIGPIPE_R, $SIGPIPE_W;	1390	pipe $SIGPIPE_R, $SIGPIPE_W;
1102	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1391	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1103	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1392	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1393
		1394	# not strictly required, as $^F is normally 2, but let's make sure...
		1395	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1396	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1104	}	1397	}
1105		1398
1106	$SIGPIPE_R	1399	$SIGPIPE_R
1107	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1400	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1108		1401
1109	# not strictly required, as $^F is normally 2, but let's make sure...
1110	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1111	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1112
1113	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1402	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1114	}	1403	}
1115		1404
1116	my $signal = uc $arg{signal}	1405	*signal = \&_signal;
1117	or Carp::croak "required option 'signal' is missing";	1406	&signal
1118
1119	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1120	$SIG{$signal} ||= sub {
1121	local $!;
1122	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1123	undef $SIG_EV{$signal};
1124	};
1125
1126	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
1127	}	1407	}
1128		1408
1129	sub AnyEvent::Base::Signal::DESTROY {	1409	sub AnyEvent::Base::signal::DESTROY {
1130	my ($signal, $cb) = @{$_[0]};	1410	my ($signal, $cb) = @{$_[0]};
1131		1411
		1412	_sig_del;
		1413
1132	delete $SIG_CB{$signal}{$cb};	1414	delete $SIG_CB{$signal}{$cb};
1133		1415
		1416	$HAVE_ASYNC_INTERRUPT
		1417	? delete $SIG_ASY{$signal}
		1418	: # delete doesn't work with older perls - they then
		1419	# print weird messages, or just unconditionally exit
		1420	# instead of getting the default action.
		1421	undef $SIG{$signal}
1134	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1422	unless keys %{ $SIG_CB{$signal} };
1135	}	1423	}
1136		1424
1137	# default implementation for ->child	1425	# default implementation for ->child
1138		1426
1139	our %PID_CB;	1427	our %PID_CB;
1140	our $CHLD_W;	1428	our $CHLD_W;
1141	our $CHLD_DELAY_W;	1429	our $CHLD_DELAY_W;
1142	our $PID_IDLE;
1143	our $WNOHANG;	1430	our $WNOHANG;
1144		1431
1145	sub _child_wait {	1432	sub _emit_childstatus($$) {
1146	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1433	my (undef, $rpid, $rstatus) = @_;
		1434
		1435	$_->($rpid, $rstatus)
1147	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1436	for values %{ $PID_CB{$rpid} || {} },
1148	(values %{ $PID_CB{0} || {} });	1437	values %{ $PID_CB{0} || {} };
1149	}
1150
1151	undef $PID_IDLE;
1152	}	1438	}
1153		1439
1154	sub _sigchld {	1440	sub _sigchld {
1155	# make sure we deliver these changes "synchronous" with the event loop.	1441	my $pid;
1156	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1442
1157	undef $CHLD_DELAY_W;	1443	AnyEvent->_emit_childstatus ($pid, $?)
1158	&_child_wait;	1444	while ($pid = waitpid -1, $WNOHANG) > 0;
1159	});
1160	}	1445	}
1161		1446
1162	sub child {	1447	sub child {
1163	my (undef, %arg) = @_;	1448	my (undef, %arg) = @_;
1164		1449
1165	defined (my $pid = $arg{pid} + 0)	1450	defined (my $pid = $arg{pid} + 0)
1166	or Carp::croak "required option 'pid' is missing";	1451	or Carp::croak "required option 'pid' is missing";
1167		1452
1168	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1453	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1169		1454
1170	unless ($WNOHANG) {	1455	# WNOHANG is almost cetrainly 1 everywhere
		1456	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1457	? 1
1171	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1458	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1172	}
1173		1459
1174	unless ($CHLD_W) {	1460	unless ($CHLD_W) {
1175	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1461	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1176	# child could be a zombie already, so make at least one round	1462	# child could be a zombie already, so make at least one round
1177	&_sigchld;	1463	&_sigchld;
1178	}	1464	}
1179		1465
1180	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1466	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1181	}	1467	}
1182		1468
1183	sub AnyEvent::Base::Child::DESTROY {	1469	sub AnyEvent::Base::child::DESTROY {
1184	my ($pid, $cb) = @{$_[0]};	1470	my ($pid, $cb) = @{$_[0]};
1185		1471
1186	delete $PID_CB{$pid}{$cb};	1472	delete $PID_CB{$pid}{$cb};
1187	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1473	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1188		1474
1189	undef $CHLD_W unless keys %PID_CB;	1475	undef $CHLD_W unless keys %PID_CB;
1190	}	1476	}
1191		1477
		1478	# idle emulation is done by simply using a timer, regardless
		1479	# of whether the process is idle or not, and not letting
		1480	# the callback use more than 50% of the time.
		1481	sub idle {
		1482	my (undef, %arg) = @_;
		1483
		1484	my ($cb, $w, $rcb) = $arg{cb};
		1485
		1486	$rcb = sub {
		1487	if ($cb) {
		1488	$w = _time;
		1489	&$cb;
		1490	$w = _time - $w;
		1491
		1492	# never use more then 50% of the time for the idle watcher,
		1493	# within some limits
		1494	$w = 0.0001 if $w < 0.0001;
		1495	$w = 5 if $w > 5;
		1496
		1497	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1498	} else {
		1499	# clean up...
		1500	undef $w;
		1501	undef $rcb;
		1502	}
		1503	};
		1504
		1505	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1506
		1507	bless \\$cb, "AnyEvent::Base::idle"
		1508	}
		1509
		1510	sub AnyEvent::Base::idle::DESTROY {
		1511	undef $${$_[0]};
		1512	}
		1513
1192	package AnyEvent::CondVar;	1514	package AnyEvent::CondVar;
1193		1515
1194	our @ISA = AnyEvent::CondVar::Base::;	1516	our @ISA = AnyEvent::CondVar::Base::;
1195		1517
1196	package AnyEvent::CondVar::Base;	1518	package AnyEvent::CondVar::Base;
1197		1519
1198	use overload	1520	#use overload
1199	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1521	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1200	fallback => 1;	1522	# fallback => 1;
		1523
		1524	# save 300+ kilobytes by dirtily hardcoding overloading
		1525	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1526	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1527	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1528	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1529
		1530	our $WAITING;
1201		1531
1202	sub _send {	1532	sub _send {
1203	# nop	1533	# nop
1204	}	1534	}
1205		1535
…		…
1218	sub ready {	1548	sub ready {
1219	$_[0]{_ae_sent}	1549	$_[0]{_ae_sent}
1220	}	1550	}
1221		1551
1222	sub _wait {	1552	sub _wait {
		1553	$WAITING
		1554	and !$_[0]{_ae_sent}
		1555	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1556
		1557	local $WAITING = 1;
1223	AnyEvent->one_event while !$_[0]{_ae_sent};	1558	AnyEvent->one_event while !$_[0]{_ae_sent};
1224	}	1559	}
1225		1560
1226	sub recv {	1561	sub recv {
1227	$_[0]->_wait;	1562	$_[0]->_wait;
…		…
1268	so on.	1603	so on.
1269		1604
1270	=head1 ENVIRONMENT VARIABLES	1605	=head1 ENVIRONMENT VARIABLES
1271		1606
1272	The following environment variables are used by this module or its	1607	The following environment variables are used by this module or its
1273	submodules:	1608	submodules.
		1609
		1610	Note that AnyEvent will remove I<all> environment variables starting with
		1611	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1612	enabled.
1274		1613
1275	=over 4	1614	=over 4
1276		1615
1277	=item C<PERL_ANYEVENT_VERBOSE>	1616	=item C<PERL_ANYEVENT_VERBOSE>
1278		1617
…		…
1285	C<PERL_ANYEVENT_MODEL>.	1624	C<PERL_ANYEVENT_MODEL>.
1286		1625
1287	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1626	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1288	model it chooses.	1627	model it chooses.
1289		1628
		1629	When set to C<8> or higher, then AnyEvent will report extra information on
		1630	which optional modules it loads and how it implements certain features.
		1631
1290	=item C<PERL_ANYEVENT_STRICT>	1632	=item C<PERL_ANYEVENT_STRICT>
1291		1633
1292	AnyEvent does not do much argument checking by default, as thorough	1634	AnyEvent does not do much argument checking by default, as thorough
1293	argument checking is very costly. Setting this variable to a true value	1635	argument checking is very costly. Setting this variable to a true value
1294	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1636	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1295	check the arguments passed to most method calls. If it finds any problems	1637	check the arguments passed to most method calls. If it finds any problems,
1296	it will croak.	1638	it will croak.
1297		1639
1298	In other words, enables "strict" mode.	1640	In other words, enables "strict" mode.
1299		1641
1300	Unlike C<use strict>, it is definitely recommended ot keep it off in	1642	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
1301	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1643	>>, it is definitely recommended to keep it off in production. Keeping
1302	developing programs can be very useful, however.	1644	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1645	can be very useful, however.
1303		1646
1304	=item C<PERL_ANYEVENT_MODEL>	1647	=item C<PERL_ANYEVENT_MODEL>
1305		1648
1306	This can be used to specify the event model to be used by AnyEvent, before	1649	This can be used to specify the event model to be used by AnyEvent, before
1307	auto detection and -probing kicks in. It must be a string consisting	1650	auto detection and -probing kicks in. It must be a string consisting
…		…
1350		1693
1351	=item C<PERL_ANYEVENT_MAX_FORKS>	1694	=item C<PERL_ANYEVENT_MAX_FORKS>
1352		1695
1353	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1696	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1354	will create in parallel.	1697	will create in parallel.
		1698
		1699	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1700
		1701	The default value for the C<max_outstanding> parameter for the default DNS
		1702	resolver - this is the maximum number of parallel DNS requests that are
		1703	sent to the DNS server.
		1704
		1705	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1706
		1707	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1708	configuration) in the default resolver. When set to the empty string, no
		1709	default config will be used.
		1710
		1711	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1712
		1713	When neither C<ca_file> nor C<ca_path> was specified during
		1714	L<AnyEvent::TLS> context creation, and either of these environment
		1715	variables exist, they will be used to specify CA certificate locations
		1716	instead of a system-dependent default.
		1717
		1718	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1719
		1720	When these are set to C<1>, then the respective modules are not
		1721	loaded. Mostly good for testing AnyEvent itself.
1355		1722
1356	=back	1723	=back
1357		1724
1358	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1725	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1359		1726
…		…
1604	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	1971	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1605	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	1972	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1606	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	1973	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1607	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	1974	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1608	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	1975	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1976	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1977	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1609	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	1978	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1610	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	1979	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1611	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	1980	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1612	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	1981	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1613		1982
…		…
1642	performance becomes really bad with lots of file descriptors (and few of	2011	performance becomes really bad with lots of file descriptors (and few of
1643	them active), of course, but this was not subject of this benchmark.	2012	them active), of course, but this was not subject of this benchmark.
1644		2013
1645	The C<Event> module has a relatively high setup and callback invocation	2014	The C<Event> module has a relatively high setup and callback invocation
1646	cost, but overall scores in on the third place.	2015	cost, but overall scores in on the third place.
		2016
		2017	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2018	when using its pure perl backend.
1647		2019
1648	C<Glib>'s memory usage is quite a bit higher, but it features a	2020	C<Glib>'s memory usage is quite a bit higher, but it features a
1649	faster callback invocation and overall ends up in the same class as	2021	faster callback invocation and overall ends up in the same class as
1650	C<Event>. However, Glib scales extremely badly, doubling the number of	2022	C<Event>. However, Glib scales extremely badly, doubling the number of
1651	watchers increases the processing time by more than a factor of four,	2023	watchers increases the processing time by more than a factor of four,
…		…
1729	it to another server. This includes deleting the old timeout and creating	2101	it to another server. This includes deleting the old timeout and creating
1730	a new one that moves the timeout into the future.	2102	a new one that moves the timeout into the future.
1731		2103
1732	=head3 Results	2104	=head3 Results
1733		2105
1734	name sockets create request	2106	name sockets create request
1735	EV 20000 69.01 11.16	2107	EV 20000 69.01 11.16
1736	Perl 20000 73.32 35.87	2108	Perl 20000 73.32 35.87
		2109	IOAsync 20000 157.00 98.14 epoll
		2110	IOAsync 20000 159.31 616.06 poll
1737	Event 20000 212.62 257.32	2111	Event 20000 212.62 257.32
1738	Glib 20000 651.16 1896.30	2112	Glib 20000 651.16 1896.30
1739	POE 20000 349.67 12317.24 uses POE::Loop::Event	2113	POE 20000 349.67 12317.24 uses POE::Loop::Event
1740		2114
1741	=head3 Discussion	2115	=head3 Discussion
1742		2116
1743	This benchmark I<does> measure scalability and overall performance of the	2117	This benchmark I<does> measure scalability and overall performance of the
1744	particular event loop.	2118	particular event loop.
…		…
1746	EV is again fastest. Since it is using epoll on my system, the setup time	2120	EV is again fastest. Since it is using epoll on my system, the setup time
1747	is relatively high, though.	2121	is relatively high, though.
1748		2122
1749	Perl surprisingly comes second. It is much faster than the C-based event	2123	Perl surprisingly comes second. It is much faster than the C-based event
1750	loops Event and Glib.	2124	loops Event and Glib.
		2125
		2126	IO::Async performs very well when using its epoll backend, and still quite
		2127	good compared to Glib when using its pure perl backend.
1751		2128
1752	Event suffers from high setup time as well (look at its code and you will	2129	Event suffers from high setup time as well (look at its code and you will
1753	understand why). Callback invocation also has a high overhead compared to	2130	understand why). Callback invocation also has a high overhead compared to
1754	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2131	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1755	uses select or poll in basically all documented configurations.	2132	uses select or poll in basically all documented configurations.
…		…
1818	=item * C-based event loops perform very well with small number of	2195	=item * C-based event loops perform very well with small number of
1819	watchers, as the management overhead dominates.	2196	watchers, as the management overhead dominates.
1820		2197
1821	=back	2198	=back
1822		2199
		2200	=head2 THE IO::Lambda BENCHMARK
		2201
		2202	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2203	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2204	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2205	shouldn't come as a surprise to anybody). As such, the benchmark is
		2206	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2207	very optimal. But how would AnyEvent compare when used without the extra
		2208	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2209
		2210	The benchmark itself creates an echo-server, and then, for 500 times,
		2211	connects to the echo server, sends a line, waits for the reply, and then
		2212	creates the next connection. This is a rather bad benchmark, as it doesn't
		2213	test the efficiency of the framework or much non-blocking I/O, but it is a
		2214	benchmark nevertheless.
		2215
		2216	name runtime
		2217	Lambda/select 0.330 sec
		2218	+ optimized 0.122 sec
		2219	Lambda/AnyEvent 0.327 sec
		2220	+ optimized 0.138 sec
		2221	Raw sockets/select 0.077 sec
		2222	POE/select, components 0.662 sec
		2223	POE/select, raw sockets 0.226 sec
		2224	POE/select, optimized 0.404 sec
		2225
		2226	AnyEvent/select/nb 0.085 sec
		2227	AnyEvent/EV/nb 0.068 sec
		2228	+state machine 0.134 sec
		2229
		2230	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2231	benchmarks actually make blocking connects and use 100% blocking I/O,
		2232	defeating the purpose of an event-based solution. All of the newly
		2233	written AnyEvent benchmarks use 100% non-blocking connects (using
		2234	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2235	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2236	generally require a lot more bookkeeping and event handling than blocking
		2237	connects (which involve a single syscall only).
		2238
		2239	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2240	offers similar expressive power as POE and IO::Lambda, using conventional
		2241	Perl syntax. This means that both the echo server and the client are 100%
		2242	non-blocking, further placing it at a disadvantage.
		2243
		2244	As you can see, the AnyEvent + EV combination even beats the
		2245	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2246	backend easily beats IO::Lambda and POE.
		2247
		2248	And even the 100% non-blocking version written using the high-level (and
		2249	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2250	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2251	in a non-blocking way.
		2252
		2253	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2254	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2255	part of the IO::lambda distribution and were used without any changes.
		2256
1823		2257
1824	=head1 SIGNALS	2258	=head1 SIGNALS
1825		2259
1826	AnyEvent currently installs handlers for these signals:	2260	AnyEvent currently installs handlers for these signals:
1827		2261
…		…
1830	=item SIGCHLD	2264	=item SIGCHLD
1831		2265
1832	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2266	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1833	emulation for event loops that do not support them natively. Also, some	2267	emulation for event loops that do not support them natively. Also, some
1834	event loops install a similar handler.	2268	event loops install a similar handler.
		2269
		2270	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2271	AnyEvent will reset it to default, to avoid losing child exit statuses.
1835		2272
1836	=item SIGPIPE	2273	=item SIGPIPE
1837		2274
1838	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2275	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1839	when AnyEvent gets loaded.	2276	when AnyEvent gets loaded.
…		…
1851		2288
1852	=back	2289	=back
1853		2290
1854	=cut	2291	=cut
1855		2292
		2293	undef $SIG{CHLD}
		2294	if $SIG{CHLD} eq 'IGNORE';
		2295
1856	$SIG{PIPE} = sub { }	2296	$SIG{PIPE} = sub { }
1857	unless defined $SIG{PIPE};	2297	unless defined $SIG{PIPE};
		2298
		2299	=head1 RECOMMENDED/OPTIONAL MODULES
		2300
		2301	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2302	it's built-in modules) are required to use it.
		2303
		2304	That does not mean that AnyEvent won't take advantage of some additional
		2305	modules if they are installed.
		2306
		2307	This section epxlains which additional modules will be used, and how they
		2308	affect AnyEvent's operetion.
		2309
		2310	=over 4
		2311
		2312	=item L<Async::Interrupt>
		2313
		2314	This slightly arcane module is used to implement fast signal handling: To
		2315	my knowledge, there is no way to do completely race-free and quick
		2316	signal handling in pure perl. To ensure that signals still get
		2317	delivered, AnyEvent will start an interval timer to wake up perl (and
		2318	catch the signals) with some delay (default is 10 seconds, look for
		2319	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2320
		2321	If this module is available, then it will be used to implement signal
		2322	catching, which means that signals will not be delayed, and the event loop
		2323	will not be interrupted regularly, which is more efficient (And good for
		2324	battery life on laptops).
		2325
		2326	This affects not just the pure-perl event loop, but also other event loops
		2327	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2328
		2329	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2330	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2331	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2332	does nothing for those backends.
		2333
		2334	=item L<EV>
		2335
		2336	This module isn't really "optional", as it is simply one of the backend
		2337	event loops that AnyEvent can use. However, it is simply the best event
		2338	loop available in terms of features, speed and stability: It supports
		2339	the AnyEvent API optimally, implements all the watcher types in XS, does
		2340	automatic timer adjustments even when no monotonic clock is available,
		2341	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2342	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2343	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2344
		2345	=item L<Guard>
		2346
		2347	The guard module, when used, will be used to implement
		2348	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2349	lot less memory), but otherwise doesn't affect guard operation much. It is
		2350	purely used for performance.
		2351
		2352	=item L<JSON> and L<JSON::XS>
		2353
		2354	This module is required when you want to read or write JSON data via
		2355	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2356	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2357
		2358	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2359	installed.
		2360
		2361	=item L<Net::SSLeay>
		2362
		2363	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2364	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2365	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2366
		2367	=item L<Time::HiRes>
		2368
		2369	This module is part of perl since release 5.008. It will be used when the
		2370	chosen event library does not come with a timing source on it's own. The
		2371	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2372	try to use a monotonic clock for timing stability.
		2373
		2374	=back
1858		2375
1859		2376
1860	=head1 FORK	2377	=head1 FORK
1861		2378
1862	Most event libraries are not fork-safe. The ones who are usually are	2379	Most event libraries are not fork-safe. The ones who are usually are
1863	because they rely on inefficient but fork-safe C<select> or C<poll>	2380	because they rely on inefficient but fork-safe C<select> or C<poll>
1864	calls. Only L<EV> is fully fork-aware.	2381	calls. Only L<EV> is fully fork-aware.
1865		2382
1866	If you have to fork, you must either do so I<before> creating your first	2383	If you have to fork, you must either do so I<before> creating your first
1867	watcher OR you must not use AnyEvent at all in the child.	2384	watcher OR you must not use AnyEvent at all in the child OR you must do
		2385	something completely out of the scope of AnyEvent.
1868		2386
1869		2387
1870	=head1 SECURITY CONSIDERATIONS	2388	=head1 SECURITY CONSIDERATIONS
1871		2389
1872	AnyEvent can be forced to load any event model via	2390	AnyEvent can be forced to load any event model via
…		…
1884	use AnyEvent;	2402	use AnyEvent;
1885		2403
1886	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2404	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1887	be used to probe what backend is used and gain other information (which is	2405	be used to probe what backend is used and gain other information (which is
1888	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2406	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1889	$ENV{PERL_ANYEGENT_STRICT}.	2407	$ENV{PERL_ANYEVENT_STRICT}.
		2408
		2409	Note that AnyEvent will remove I<all> environment variables starting with
		2410	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2411	enabled.
1890		2412
1891		2413
1892	=head1 BUGS	2414	=head1 BUGS
1893		2415
1894	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2416	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
…		…
1906	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2428	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1907		2429
1908	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2430	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1909	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2431	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1910	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2432	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1911	L<AnyEvent::Impl::POE>.	2433	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1912		2434
1913	Non-blocking file handles, sockets, TCP clients and	2435	Non-blocking file handles, sockets, TCP clients and
1914	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2436	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1915		2437
1916	Asynchronous DNS: L<AnyEvent::DNS>.	2438	Asynchronous DNS: L<AnyEvent::DNS>.
1917		2439
1918	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2440	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2441	L<Coro::Event>,
1919		2442
1920	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2443	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2444	L<AnyEvent::HTTP>.
1921		2445
1922		2446
1923	=head1 AUTHOR	2447	=head1 AUTHOR
1924		2448
1925	Marc Lehmann <schmorp@schmorp.de>	2449	Marc Lehmann <schmorp@schmorp.de>

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