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Revision 1.196 by root, Thu Mar 26 07:47:42 2009 UTC vs.
Revision 1.246 by root, Sat Jul 18 15:51:52 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
12		14
		15	# one-shot or repeating timers
13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
15		18
16	print AnyEvent->now; # prints current event loop time	19	print AnyEvent->now; # prints current event loop time
17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
18		21
		22	# POSIX signal
19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });	23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
20		24
		25	# child process exit
21	my $w = AnyEvent->child (pid => $pid, cb => sub {	26	my $w = AnyEvent->child (pid => $pid, cb => sub {
22	my ($pid, $status) = @_;	27	my ($pid, $status) = @_;
23	...	28	...
24	});	29	});
		30
		31	# called when event loop idle (if applicable)
		32	my $w = AnyEvent->idle (cb => sub { ... });
25		33
26	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
27	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
28	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
29	# use a condvar in callback mode:	37	# use a condvar in callback mode:
…		…
168	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
169		177
170	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
171	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
172		180
173	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	181	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
174	(AnyEvent might or might not keep a reference to this file handle). C<poll>	182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
175	must be a string that is either C<r> or C<w>, which creates a watcher	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
176	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
177	callback to invoke each time the file handle becomes ready.	191	C<cb> is the callback to invoke each time the file handle becomes ready.
178		192
179	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
180	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
181	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
182		196
…		…
314	In either case, if you care (and in most cases, you don't), then you	328	In either case, if you care (and in most cases, you don't), then you
315	can get whatever behaviour you want with any event loop, by taking the	329	can get whatever behaviour you want with any event loop, by taking the
316	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
317	account.	331	account.
318		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
319	=back	348	=back
320		349
321	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
322		351
323	You can watch for signals using a signal watcher, C<signal> is the signal	352	You can watch for signals using a signal watcher, C<signal> is the signal
…		…
332	invocation, and callback invocation will be synchronous. Synchronous means	361	invocation, and callback invocation will be synchronous. Synchronous means
333	that it might take a while until the signal gets handled by the process,	362	that it might take a while until the signal gets handled by the process,
334	but it is guaranteed not to interrupt any other callbacks.	363	but it is guaranteed not to interrupt any other callbacks.
335		364
336	The main advantage of using these watchers is that you can share a signal	365	The main advantage of using these watchers is that you can share a signal
337	between multiple watchers.	366	between multiple watchers, and AnyEvent will ensure that signals will not
		367	interrupt your program at bad times.
338		368
339	This watcher might use C<%SIG>, so programs overwriting those signals	369	This watcher might use C<%SIG> (depending on the event loop used),
340	directly will likely not work correctly.	370	so programs overwriting those signals directly will likely not work
		371	correctly.
		372
		373	Also note that many event loops (e.g. Glib, Tk, Qt, IO::Async) do not
		374	support attaching callbacks to signals, which is a pity, as you cannot do
		375	race-free signal handling in perl. AnyEvent will try to do it's best, but
		376	in some cases, signals will be delayed. The maximum time a signal might
		377	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		378	seconds). This variable can be changed only before the first signal
		379	watcher is created, and should be left alone otherwise. Higher values
		380	will cause fewer spurious wake-ups, which is better for power and CPU
		381	saving. All these problems can be avoided by installing the optional
		382	L<Async::Interrupt> module.
341		383
342	Example: exit on SIGINT	384	Example: exit on SIGINT
343		385
344	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	386	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
345		387
…		…
363		405
364	There is a slight catch to child watchers, however: you usually start them	406	There is a slight catch to child watchers, however: you usually start them
365	I<after> the child process was created, and this means the process could	407	I<after> the child process was created, and this means the process could
366	have exited already (and no SIGCHLD will be sent anymore).	408	have exited already (and no SIGCHLD will be sent anymore).
367		409
368	Not all event models handle this correctly (POE doesn't), but even for	410	Not all event models handle this correctly (neither POE nor IO::Async do,
		411	see their AnyEvent::Impl manpages for details), but even for event models
369	event models that I<do> handle this correctly, they usually need to be	412	that I<do> handle this correctly, they usually need to be loaded before
370	loaded before the process exits (i.e. before you fork in the first place).	413	the process exits (i.e. before you fork in the first place). AnyEvent's
		414	pure perl event loop handles all cases correctly regardless of when you
		415	start the watcher.
371		416
372	This means you cannot create a child watcher as the very first thing in an	417	This means you cannot create a child watcher as the very first
373	AnyEvent program, you I<have> to create at least one watcher before you	418	thing in an AnyEvent program, you I<have> to create at least one
374	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	419	watcher before you C<fork> the child (alternatively, you can call
		420	C<AnyEvent::detect>).
		421
		422	As most event loops do not support waiting for child events, they will be
		423	emulated by AnyEvent in most cases, in which the latency and race problems
		424	mentioned in the description of signal watchers apply.
375		425
376	Example: fork a process and wait for it	426	Example: fork a process and wait for it
377		427
378	my $done = AnyEvent->condvar;	428	my $done = AnyEvent->condvar;
379		429
…		…
389	);	439	);
390		440
391	# do something else, then wait for process exit	441	# do something else, then wait for process exit
392	$done->recv;	442	$done->recv;
393		443
		444	=head2 IDLE WATCHERS
		445
		446	Sometimes there is a need to do something, but it is not so important
		447	to do it instantly, but only when there is nothing better to do. This
		448	"nothing better to do" is usually defined to be "no other events need
		449	attention by the event loop".
		450
		451	Idle watchers ideally get invoked when the event loop has nothing
		452	better to do, just before it would block the process to wait for new
		453	events. Instead of blocking, the idle watcher is invoked.
		454
		455	Most event loops unfortunately do not really support idle watchers (only
		456	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		457	will simply call the callback "from time to time".
		458
		459	Example: read lines from STDIN, but only process them when the
		460	program is otherwise idle:
		461
		462	my @lines; # read data
		463	my $idle_w;
		464	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		465	push @lines, scalar <STDIN>;
		466
		467	# start an idle watcher, if not already done
		468	$idle_w ||= AnyEvent->idle (cb => sub {
		469	# handle only one line, when there are lines left
		470	if (my $line = shift @lines) {
		471	print "handled when idle: $line";
		472	} else {
		473	# otherwise disable the idle watcher again
		474	undef $idle_w;
		475	}
		476	});
		477	});
		478
394	=head2 CONDITION VARIABLES	479	=head2 CONDITION VARIABLES
395		480
396	If you are familiar with some event loops you will know that all of them	481	If you are familiar with some event loops you will know that all of them
397	require you to run some blocking "loop", "run" or similar function that	482	require you to run some blocking "loop", "run" or similar function that
398	will actively watch for new events and call your callbacks.	483	will actively watch for new events and call your callbacks.
399		484
400	AnyEvent is different, it expects somebody else to run the event loop and	485	AnyEvent is slightly different: it expects somebody else to run the event
401	will only block when necessary (usually when told by the user).	486	loop and will only block when necessary (usually when told by the user).
402		487
403	The instrument to do that is called a "condition variable", so called	488	The instrument to do that is called a "condition variable", so called
404	because they represent a condition that must become true.	489	because they represent a condition that must become true.
405		490
		491	Now is probably a good time to look at the examples further below.
		492
406	Condition variables can be created by calling the C<< AnyEvent->condvar	493	Condition variables can be created by calling the C<< AnyEvent->condvar
407	>> method, usually without arguments. The only argument pair allowed is	494	>> method, usually without arguments. The only argument pair allowed is
408
409	C<cb>, which specifies a callback to be called when the condition variable	495	C<cb>, which specifies a callback to be called when the condition variable
410	becomes true, with the condition variable as the first argument (but not	496	becomes true, with the condition variable as the first argument (but not
411	the results).	497	the results).
412		498
413	After creation, the condition variable is "false" until it becomes "true"	499	After creation, the condition variable is "false" until it becomes "true"
…		…
462	after => 1,	548	after => 1,
463	cb => sub { $result_ready->send },	549	cb => sub { $result_ready->send },
464	);	550	);
465		551
466	# this "blocks" (while handling events) till the callback	552	# this "blocks" (while handling events) till the callback
467	# calls send	553	# calls -<send
468	$result_ready->recv;	554	$result_ready->recv;
469		555
470	Example: wait for a timer, but take advantage of the fact that	556	Example: wait for a timer, but take advantage of the fact that condition
471	condition variables are also code references.	557	variables are also callable directly.
472		558
473	my $done = AnyEvent->condvar;	559	my $done = AnyEvent->condvar;
474	my $delay = AnyEvent->timer (after => 5, cb => $done);	560	my $delay = AnyEvent->timer (after => 5, cb => $done);
475	$done->recv;	561	$done->recv;
476		562
…		…
482		568
483	...	569	...
484		570
485	my @info = $couchdb->info->recv;	571	my @info = $couchdb->info->recv;
486		572
487	And this is how you would just ste a callback to be called whenever the	573	And this is how you would just set a callback to be called whenever the
488	results are available:	574	results are available:
489		575
490	$couchdb->info->cb (sub {	576	$couchdb->info->cb (sub {
491	my @info = $_[0]->recv;	577	my @info = $_[0]->recv;
492	});	578	});
…		…
510	immediately from within send.	596	immediately from within send.
511		597
512	Any arguments passed to the C<send> call will be returned by all	598	Any arguments passed to the C<send> call will be returned by all
513	future C<< ->recv >> calls.	599	future C<< ->recv >> calls.
514		600
515	Condition variables are overloaded so one can call them directly	601	Condition variables are overloaded so one can call them directly (as if
516	(as a code reference). Calling them directly is the same as calling	602	they were a code reference). Calling them directly is the same as calling
517	C<send>. Note, however, that many C-based event loops do not handle	603	C<send>.
518	overloading, so as tempting as it may be, passing a condition variable
519	instead of a callback does not work. Both the pure perl and EV loops
520	support overloading, however, as well as all functions that use perl to
521	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
522	example).
523		604
524	=item $cv->croak ($error)	605	=item $cv->croak ($error)
525		606
526	Similar to send, but causes all call's to C<< ->recv >> to invoke	607	Similar to send, but causes all call's to C<< ->recv >> to invoke
527	C<Carp::croak> with the given error message/object/scalar.	608	C<Carp::croak> with the given error message/object/scalar.
528		609
529	This can be used to signal any errors to the condition variable	610	This can be used to signal any errors to the condition variable
530	user/consumer.	611	user/consumer. Doing it this way instead of calling C<croak> directly
		612	delays the error detetcion, but has the overwhelmign advantage that it
		613	diagnoses the error at the place where the result is expected, and not
		614	deep in some event clalback without connection to the actual code causing
		615	the problem.
531		616
532	=item $cv->begin ([group callback])	617	=item $cv->begin ([group callback])
533		618
534	=item $cv->end	619	=item $cv->end
535
536	These two methods are EXPERIMENTAL and MIGHT CHANGE.
537		620
538	These two methods can be used to combine many transactions/events into	621	These two methods can be used to combine many transactions/events into
539	one. For example, a function that pings many hosts in parallel might want	622	one. For example, a function that pings many hosts in parallel might want
540	to use a condition variable for the whole process.	623	to use a condition variable for the whole process.
541		624
…		…
543	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	626	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
544	>>, the (last) callback passed to C<begin> will be executed. That callback	627	>>, the (last) callback passed to C<begin> will be executed. That callback
545	is I<supposed> to call C<< ->send >>, but that is not required. If no	628	is I<supposed> to call C<< ->send >>, but that is not required. If no
546	callback was set, C<send> will be called without any arguments.	629	callback was set, C<send> will be called without any arguments.
547		630
548	Let's clarify this with the ping example:	631	You can think of C<< $cv->send >> giving you an OR condition (one call
		632	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		633	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		634
		635	Let's start with a simple example: you have two I/O watchers (for example,
		636	STDOUT and STDERR for a program), and you want to wait for both streams to
		637	close before activating a condvar:
		638
		639	my $cv = AnyEvent->condvar;
		640
		641	$cv->begin; # first watcher
		642	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		643	defined sysread $fh1, my $buf, 4096
		644	or $cv->end;
		645	});
		646
		647	$cv->begin; # second watcher
		648	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		649	defined sysread $fh2, my $buf, 4096
		650	or $cv->end;
		651	});
		652
		653	$cv->recv;
		654
		655	This works because for every event source (EOF on file handle), there is
		656	one call to C<begin>, so the condvar waits for all calls to C<end> before
		657	sending.
		658
		659	The ping example mentioned above is slightly more complicated, as the
		660	there are results to be passwd back, and the number of tasks that are
		661	begung can potentially be zero:
549		662
550	my $cv = AnyEvent->condvar;	663	my $cv = AnyEvent->condvar;
551		664
552	my %result;	665	my %result;
553	$cv->begin (sub { $cv->send (\%result) });	666	$cv->begin (sub { $cv->send (\%result) });
…		…
573	loop, which serves two important purposes: first, it sets the callback	686	loop, which serves two important purposes: first, it sets the callback
574	to be called once the counter reaches C<0>, and second, it ensures that	687	to be called once the counter reaches C<0>, and second, it ensures that
575	C<send> is called even when C<no> hosts are being pinged (the loop	688	C<send> is called even when C<no> hosts are being pinged (the loop
576	doesn't execute once).	689	doesn't execute once).
577		690
578	This is the general pattern when you "fan out" into multiple subrequests:	691	This is the general pattern when you "fan out" into multiple (but
579	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	692	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
580	is called at least once, and then, for each subrequest you start, call	693	the callback and ensure C<end> is called at least once, and then, for each
581	C<begin> and for each subrequest you finish, call C<end>.	694	subrequest you start, call C<begin> and for each subrequest you finish,
		695	call C<end>.
582		696
583	=back	697	=back
584		698
585	=head3 METHODS FOR CONSUMERS	699	=head3 METHODS FOR CONSUMERS
586		700
…		…
602	function will call C<croak>.	716	function will call C<croak>.
603		717
604	In list context, all parameters passed to C<send> will be returned,	718	In list context, all parameters passed to C<send> will be returned,
605	in scalar context only the first one will be returned.	719	in scalar context only the first one will be returned.
606		720
		721	Note that doing a blocking wait in a callback is not supported by any
		722	event loop, that is, recursive invocation of a blocking C<< ->recv
		723	>> is not allowed, and the C<recv> call will C<croak> if such a
		724	condition is detected. This condition can be slightly loosened by using
		725	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		726	any thread that doesn't run the event loop itself.
		727
607	Not all event models support a blocking wait - some die in that case	728	Not all event models support a blocking wait - some die in that case
608	(programs might want to do that to stay interactive), so I<if you are	729	(programs might want to do that to stay interactive), so I<if you are
609	using this from a module, never require a blocking wait>, but let the	730	using this from a module, never require a blocking wait>. Instead, let the
610	caller decide whether the call will block or not (for example, by coupling	731	caller decide whether the call will block or not (for example, by coupling
611	condition variables with some kind of request results and supporting	732	condition variables with some kind of request results and supporting
612	callbacks so the caller knows that getting the result will not block,	733	callbacks so the caller knows that getting the result will not block,
613	while still supporting blocking waits if the caller so desires).	734	while still supporting blocking waits if the caller so desires).
614		735
615	Another reason I<never> to C<< ->recv >> in a module is that you cannot
616	sensibly have two C<< ->recv >>'s in parallel, as that would require
617	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
618	can supply.
619
620	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
621	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
622	versions and also integrates coroutines into AnyEvent, making blocking
623	C<< ->recv >> calls perfectly safe as long as they are done from another
624	coroutine (one that doesn't run the event loop).
625
626	You can ensure that C<< -recv >> never blocks by setting a callback and	736	You can ensure that C<< -recv >> never blocks by setting a callback and
627	only calling C<< ->recv >> from within that callback (or at a later	737	only calling C<< ->recv >> from within that callback (or at a later
628	time). This will work even when the event loop does not support blocking	738	time). This will work even when the event loop does not support blocking
629	waits otherwise.	739	waits otherwise.
630		740
…		…
643	variable itself. Calling C<recv> inside the callback or at any later time	753	variable itself. Calling C<recv> inside the callback or at any later time
644	is guaranteed not to block.	754	is guaranteed not to block.
645		755
646	=back	756	=back
647		757
		758	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		759
		760	The available backend classes are (every class has its own manpage):
		761
		762	=over 4
		763
		764	=item Backends that are autoprobed when no other event loop can be found.
		765
		766	EV is the preferred backend when no other event loop seems to be in
		767	use. If EV is not installed, then AnyEvent will try Event, and, failing
		768	that, will fall back to its own pure-perl implementation, which is
		769	available everywhere as it comes with AnyEvent itself.
		770
		771	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		772	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		773	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		774
		775	=item Backends that are transparently being picked up when they are used.
		776
		777	These will be used when they are currently loaded when the first watcher
		778	is created, in which case it is assumed that the application is using
		779	them. This means that AnyEvent will automatically pick the right backend
		780	when the main program loads an event module before anything starts to
		781	create watchers. Nothing special needs to be done by the main program.
		782
		783	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		784	AnyEvent::Impl::Tk based on Tk, very broken.
		785	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		786	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		787
		788	=item Backends with special needs.
		789
		790	Qt requires the Qt::Application to be instantiated first, but will
		791	otherwise be picked up automatically. As long as the main program
		792	instantiates the application before any AnyEvent watchers are created,
		793	everything should just work.
		794
		795	AnyEvent::Impl::Qt based on Qt.
		796
		797	Support for IO::Async can only be partial, as it is too broken and
		798	architecturally limited to even support the AnyEvent API. It also
		799	is the only event loop that needs the loop to be set explicitly, so
		800	it can only be used by a main program knowing about AnyEvent. See
		801	L<AnyEvent::Impl::Async> for the gory details.
		802
		803	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		804
		805	=item Event loops that are indirectly supported via other backends.
		806
		807	Some event loops can be supported via other modules:
		808
		809	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		810
		811	B<WxWidgets> has no support for watching file handles. However, you can
		812	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		813	polls 20 times per second, which was considered to be too horrible to even
		814	consider for AnyEvent.
		815
		816	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		817	backend, so it can be supported through POE.
		818
		819	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		820	load L<POE> when detecting them, in the hope that POE will pick them up,
		821	in which case everything will be automatic.
		822
		823	=back
		824
648	=head1 GLOBAL VARIABLES AND FUNCTIONS	825	=head1 GLOBAL VARIABLES AND FUNCTIONS
649		826
		827	These are not normally required to use AnyEvent, but can be useful to
		828	write AnyEvent extension modules.
		829
650	=over 4	830	=over 4
651		831
652	=item $AnyEvent::MODEL	832	=item $AnyEvent::MODEL
653		833
654	Contains C<undef> until the first watcher is being created. Then it	834	Contains C<undef> until the first watcher is being created, before the
		835	backend has been autodetected.
		836
655	contains the event model that is being used, which is the name of the	837	Afterwards it contains the event model that is being used, which is the
656	Perl class implementing the model. This class is usually one of the	838	name of the Perl class implementing the model. This class is usually one
657	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	839	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
658	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	840	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
659		841	will be C<urxvt::anyevent>).
660	The known classes so far are:
661
662	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
663	AnyEvent::Impl::Event based on Event, second best choice.
664	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
665	AnyEvent::Impl::Glib based on Glib, third-best choice.
666	AnyEvent::Impl::Tk based on Tk, very bad choice.
667	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
668	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
669	AnyEvent::Impl::POE based on POE, not generic enough for full support.
670
671	There is no support for WxWidgets, as WxWidgets has no support for
672	watching file handles. However, you can use WxWidgets through the
673	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
674	second, which was considered to be too horrible to even consider for
675	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
676	it's adaptor.
677
678	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
679	autodetecting them.
680		842
681	=item AnyEvent::detect	843	=item AnyEvent::detect
682		844
683	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	845	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
684	if necessary. You should only call this function right before you would	846	if necessary. You should only call this function right before you would
685	have created an AnyEvent watcher anyway, that is, as late as possible at	847	have created an AnyEvent watcher anyway, that is, as late as possible at
686	runtime.	848	runtime, and not e.g. while initialising of your module.
		849
		850	If you need to do some initialisation before AnyEvent watchers are
		851	created, use C<post_detect>.
687		852
688	=item $guard = AnyEvent::post_detect { BLOCK }	853	=item $guard = AnyEvent::post_detect { BLOCK }
689		854
690	Arranges for the code block to be executed as soon as the event model is	855	Arranges for the code block to be executed as soon as the event model is
691	autodetected (or immediately if this has already happened).	856	autodetected (or immediately if this has already happened).
		857
		858	The block will be executed I<after> the actual backend has been detected
		859	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		860	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		861	other initialisations - see the sources of L<AnyEvent::Strict> or
		862	L<AnyEvent::AIO> to see how this is used.
		863
		864	The most common usage is to create some global watchers, without forcing
		865	event module detection too early, for example, L<AnyEvent::AIO> creates
		866	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		867	avoid autodetecting the event module at load time.
692		868
693	If called in scalar or list context, then it creates and returns an object	869	If called in scalar or list context, then it creates and returns an object
694	that automatically removes the callback again when it is destroyed. See	870	that automatically removes the callback again when it is destroyed. See
695	L<Coro::BDB> for a case where this is useful.	871	L<Coro::BDB> for a case where this is useful.
696		872
…		…
699	If there are any code references in this array (you can C<push> to it	875	If there are any code references in this array (you can C<push> to it
700	before or after loading AnyEvent), then they will called directly after	876	before or after loading AnyEvent), then they will called directly after
701	the event loop has been chosen.	877	the event loop has been chosen.
702		878
703	You should check C<$AnyEvent::MODEL> before adding to this array, though:	879	You should check C<$AnyEvent::MODEL> before adding to this array, though:
704	if it contains a true value then the event loop has already been detected,	880	if it is defined then the event loop has already been detected, and the
705	and the array will be ignored.	881	array will be ignored.
706		882
707	Best use C<AnyEvent::post_detect { BLOCK }> instead.	883	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		884	it,as it takes care of these details.
		885
		886	This variable is mainly useful for modules that can do something useful
		887	when AnyEvent is used and thus want to know when it is initialised, but do
		888	not need to even load it by default. This array provides the means to hook
		889	into AnyEvent passively, without loading it.
708		890
709	=back	891	=back
710		892
711	=head1 WHAT TO DO IN A MODULE	893	=head1 WHAT TO DO IN A MODULE
712		894
…		…
767		949
768		950
769	=head1 OTHER MODULES	951	=head1 OTHER MODULES
770		952
771	The following is a non-exhaustive list of additional modules that use	953	The following is a non-exhaustive list of additional modules that use
772	AnyEvent and can therefore be mixed easily with other AnyEvent modules	954	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
773	in the same program. Some of the modules come with AnyEvent, some are	955	modules and other event loops in the same program. Some of the modules
774	available via CPAN.	956	come with AnyEvent, most are available via CPAN.
775		957
776	=over 4	958	=over 4
777		959
778	=item L<AnyEvent::Util>	960	=item L<AnyEvent::Util>
779		961
…		…
788		970
789	=item L<AnyEvent::Handle>	971	=item L<AnyEvent::Handle>
790		972
791	Provide read and write buffers, manages watchers for reads and writes,	973	Provide read and write buffers, manages watchers for reads and writes,
792	supports raw and formatted I/O, I/O queued and fully transparent and	974	supports raw and formatted I/O, I/O queued and fully transparent and
793	non-blocking SSL/TLS.	975	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
794		976
795	=item L<AnyEvent::DNS>	977	=item L<AnyEvent::DNS>
796		978
797	Provides rich asynchronous DNS resolver capabilities.	979	Provides rich asynchronous DNS resolver capabilities.
798		980
…		…
826		1008
827	=item L<AnyEvent::GPSD>	1009	=item L<AnyEvent::GPSD>
828		1010
829	A non-blocking interface to gpsd, a daemon delivering GPS information.	1011	A non-blocking interface to gpsd, a daemon delivering GPS information.
830		1012
		1013	=item L<AnyEvent::IRC>
		1014
		1015	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1016
		1017	=item L<AnyEvent::XMPP>
		1018
		1019	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1020	Net::XMPP2>.
		1021
831	=item L<AnyEvent::IGS>	1022	=item L<AnyEvent::IGS>
832		1023
833	A non-blocking interface to the Internet Go Server protocol (used by	1024	A non-blocking interface to the Internet Go Server protocol (used by
834	L<App::IGS>).	1025	L<App::IGS>).
835		1026
836	=item L<AnyEvent::IRC>
837
838	AnyEvent based IRC client module family (replacing the older Net::IRC3).
839
840	=item L<Net::XMPP2>
841
842	AnyEvent based XMPP (Jabber protocol) module family.
843
844	=item L<Net::FCP>	1027	=item L<Net::FCP>
845		1028
846	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1029	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
847	of AnyEvent.	1030	of AnyEvent.
848		1031
…		…
852		1035
853	=item L<Coro>	1036	=item L<Coro>
854		1037
855	Has special support for AnyEvent via L<Coro::AnyEvent>.	1038	Has special support for AnyEvent via L<Coro::AnyEvent>.
856		1039
857	=item L<IO::Lambda>
858
859	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
860
861	=back	1040	=back
862		1041
863	=cut	1042	=cut
864		1043
865	package AnyEvent;	1044	package AnyEvent;
866		1045
		1046	# basically a tuned-down version of common::sense
		1047	sub common_sense {
867	no warnings;	1048	# no warnings
		1049	${^WARNING_BITS} ^= ${^WARNING_BITS};
868	use strict qw(vars subs);	1050	# use strict vars subs
		1051	$^H |= 0x00000600;
		1052	}
869		1053
		1054	BEGIN { AnyEvent::common_sense }
		1055
870	use Carp;	1056	use Carp ();
871		1057
872	our $VERSION = 4.341;	1058	our $VERSION = 4.85;
873	our $MODEL;	1059	our $MODEL;
874		1060
875	our $AUTOLOAD;	1061	our $AUTOLOAD;
876	our @ISA;	1062	our @ISA;
877		1063
878	our @REGISTRY;	1064	our @REGISTRY;
879		1065
880	our $WIN32;	1066	our $WIN32;
881		1067
		1068	our $VERBOSE;
		1069
882	BEGIN {	1070	BEGIN {
883	my $win32 = ! ! ($^O =~ /mswin32/i);	1071	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
884	eval "sub WIN32(){ $win32 }";	1072	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
885	}
886		1073
		1074	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1075	if ${^TAINT};
		1076
887	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1077	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1078
		1079	}
		1080
		1081	our $MAX_SIGNAL_LATENCY = 10;
888		1082
889	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1083	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
890		1084
891	{	1085	{
892	my $idx;	1086	my $idx;
…		…
900	[Event:: => AnyEvent::Impl::Event::],	1094	[Event:: => AnyEvent::Impl::Event::],
901	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1095	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
902	# everything below here will not be autoprobed	1096	# everything below here will not be autoprobed
903	# as the pureperl backend should work everywhere	1097	# as the pureperl backend should work everywhere
904	# and is usually faster	1098	# and is usually faster
905	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
906	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1099	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
907	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1100	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1101	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
908	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1102	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
909	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1103	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
910	[Wx:: => AnyEvent::Impl::POE::],	1104	[Wx:: => AnyEvent::Impl::POE::],
911	[Prima:: => AnyEvent::Impl::POE::],	1105	[Prima:: => AnyEvent::Impl::POE::],
		1106	# IO::Async is just too broken - we would need workarounds for its
		1107	# byzantine signal and broken child handling, among others.
		1108	# IO::Async is rather hard to detect, as it doesn't have any
		1109	# obvious default class.
		1110	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1111	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1112	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
912	);	1113	);
913		1114
914	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1115	our %method = map +($_ => 1),
		1116	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
915		1117
916	our @post_detect;	1118	our @post_detect;
917		1119
918	sub post_detect(&) {	1120	sub post_detect(&) {
919	my ($cb) = @_;	1121	my ($cb) = @_;
…		…
924	1	1126	1
925	} else {	1127	} else {
926	push @post_detect, $cb;	1128	push @post_detect, $cb;
927		1129
928	defined wantarray	1130	defined wantarray
929	? bless \$cb, "AnyEvent::Util::PostDetect"	1131	? bless \$cb, "AnyEvent::Util::postdetect"
930	: ()	1132	: ()
931	}	1133	}
932	}	1134	}
933		1135
934	sub AnyEvent::Util::PostDetect::DESTROY {	1136	sub AnyEvent::Util::postdetect::DESTROY {
935	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1137	@post_detect = grep $_ != ${$_[0]}, @post_detect;
936	}	1138	}
937		1139
938	sub detect() {	1140	sub detect() {
939	unless ($MODEL) {	1141	unless ($MODEL) {
940	no strict 'refs';
941	local $SIG{__DIE__};	1142	local $SIG{__DIE__};
942		1143
943	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1144	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
944	my $model = "AnyEvent::Impl::$1";	1145	my $model = "AnyEvent::Impl::$1";
945	if (eval "require $model") {	1146	if (eval "require $model") {
946	$MODEL = $model;	1147	$MODEL = $model;
947	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1148	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
948	} else {	1149	} else {
949	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1150	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
950	}	1151	}
951	}	1152	}
952		1153
953	# check for already loaded models	1154	# check for already loaded models
954	unless ($MODEL) {	1155	unless ($MODEL) {
955	for (@REGISTRY, @models) {	1156	for (@REGISTRY, @models) {
956	my ($package, $model) = @$_;	1157	my ($package, $model) = @$_;
957	if (${"$package\::VERSION"} > 0) {	1158	if (${"$package\::VERSION"} > 0) {
958	if (eval "require $model") {	1159	if (eval "require $model") {
959	$MODEL = $model;	1160	$MODEL = $model;
960	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1161	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
961	last;	1162	last;
962	}	1163	}
963	}	1164	}
964	}	1165	}
965		1166
…		…
970	my ($package, $model) = @$_;	1171	my ($package, $model) = @$_;
971	if (eval "require $package"	1172	if (eval "require $package"
972	and ${"$package\::VERSION"} > 0	1173	and ${"$package\::VERSION"} > 0
973	and eval "require $model") {	1174	and eval "require $model") {
974	$MODEL = $model;	1175	$MODEL = $model;
975	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1176	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
976	last;	1177	last;
977	}	1178	}
978	}	1179	}
979		1180
980	$MODEL	1181	$MODEL
981	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1182	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
982	}	1183	}
983	}	1184	}
984		1185
985	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1186	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
986		1187
…		…
996		1197
997	sub AUTOLOAD {	1198	sub AUTOLOAD {
998	(my $func = $AUTOLOAD) =~ s/.*://;	1199	(my $func = $AUTOLOAD) =~ s/.*://;
999		1200
1000	$method{$func}	1201	$method{$func}
1001	or croak "$func: not a valid method for AnyEvent objects";	1202	or Carp::croak "$func: not a valid method for AnyEvent objects";
1002		1203
1003	detect unless $MODEL;	1204	detect unless $MODEL;
1004		1205
1005	my $class = shift;	1206	my $class = shift;
1006	$class->$func (@_);	1207	$class->$func (@_);
1007	}	1208	}
1008		1209
1009	# utility function to dup a filehandle. this is used by many backends	1210	# utility function to dup a filehandle. this is used by many backends
1010	# to support binding more than one watcher per filehandle (they usually	1211	# to support binding more than one watcher per filehandle (they usually
1011	# allow only one watcher per fd, so we dup it to get a different one).	1212	# allow only one watcher per fd, so we dup it to get a different one).
1012	sub _dupfh($$$$) {	1213	sub _dupfh($$;$$) {
1013	my ($poll, $fh, $r, $w) = @_;	1214	my ($poll, $fh, $r, $w) = @_;
1014		1215
1015	# cygwin requires the fh mode to be matching, unix doesn't	1216	# cygwin requires the fh mode to be matching, unix doesn't
1016	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1217	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1017	: $poll eq "w" ? ($w, ">")
1018	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1019		1218
1020	open my $fh2, "$mode&" . fileno $fh	1219	open my $fh2, $mode, $fh
1021	or die "cannot dup() filehandle: $!";	1220	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1022		1221
1023	# we assume CLOEXEC is already set by perl in all important cases	1222	# we assume CLOEXEC is already set by perl in all important cases
1024		1223
1025	($fh2, $rw)	1224	($fh2, $rw)
1026	}	1225	}
1027		1226
1028	package AnyEvent::Base;	1227	package AnyEvent::Base;
1029		1228
1030	# default implementation for now and time	1229	# default implementations for many methods
1031		1230
1032	BEGIN {	1231	sub _time {
		1232	# probe for availability of Time::HiRes
1033	if (eval "use Time::HiRes (); time (); 1") {	1233	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1234	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1034	*_time = \&Time::HiRes::time;	1235	*_time = \&Time::HiRes::time;
1035	# if (eval "use POSIX (); (POSIX::times())...	1236	# if (eval "use POSIX (); (POSIX::times())...
1036	} else {	1237	} else {
		1238	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1037	*_time = sub { time }; # epic fail	1239	*_time = sub { time }; # epic fail
1038	}	1240	}
		1241
		1242	&_time
1039	}	1243	}
1040		1244
1041	sub time { _time }	1245	sub time { _time }
1042	sub now { _time }	1246	sub now { _time }
		1247	sub now_update { }
1043		1248
1044	# default implementation for ->condvar	1249	# default implementation for ->condvar
1045		1250
1046	sub condvar {	1251	sub condvar {
1047	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1252	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1048	}	1253	}
1049		1254
1050	# default implementation for ->signal	1255	# default implementation for ->signal
1051		1256
		1257	our $HAVE_ASYNC_INTERRUPT;
1052	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1258	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1259	our (%SIG_ASY, %SIG_ASY_W);
		1260	our ($SIG_COUNT, $SIG_TW);
1053		1261
1054	sub _signal_exec {	1262	sub _signal_exec {
		1263	$HAVE_ASYNC_INTERRUPT
		1264	? $SIGPIPE_R->drain
		1265	: sysread $SIGPIPE_R, my $dummy, 9;
		1266
1055	while (%SIG_EV) {	1267	while (%SIG_EV) {
1056	sysread $SIGPIPE_R, my $dummy, 4;
1057	for (keys %SIG_EV) {	1268	for (keys %SIG_EV) {
1058	delete $SIG_EV{$_};	1269	delete $SIG_EV{$_};
1059	$_->() for values %{ $SIG_CB{$_} || {} };	1270	$_->() for values %{ $SIG_CB{$_} || {} };
1060	}	1271	}
1061	}	1272	}
1062	}	1273	}
1063		1274
		1275	# install a dumym wakeupw atcher to reduce signal catching latency
		1276	sub _sig_add() {
		1277	unless ($SIG_COUNT++) {
		1278	# try to align timer on a full-second boundary, if possible
		1279	my $NOW = AnyEvent->now;
		1280
		1281	$SIG_TW = AnyEvent->timer (
		1282	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1283	interval => $MAX_SIGNAL_LATENCY,
		1284	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1285	);
		1286	}
		1287	}
		1288
		1289	sub _sig_del {
		1290	undef $SIG_TW
		1291	unless --$SIG_COUNT;
		1292	}
		1293
		1294	sub _signal {
		1295	my (undef, %arg) = @_;
		1296
		1297	my $signal = uc $arg{signal}
		1298	or Carp::croak "required option 'signal' is missing";
		1299
		1300	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1301
		1302	if ($HAVE_ASYNC_INTERRUPT) {
		1303	# async::interrupt
		1304
		1305	$SIG_ASY{$signal} ||= do {
		1306	my $asy = new Async::Interrupt
		1307	cb => sub { undef $SIG_EV{$signal} },
		1308	signal => $signal,
		1309	pipe => [$SIGPIPE_R->filenos],
		1310	;
		1311	$asy->pipe_autodrain (0);
		1312
		1313	$asy
		1314	};
		1315
		1316	} else {
		1317	# pure perl
		1318
		1319	$SIG{$signal} ||= sub {
		1320	local $!;
		1321	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1322	undef $SIG_EV{$signal};
		1323	};
		1324
		1325	# can't do signal processing without introducing races in pure perl,
		1326	# so limit the signal latency.
		1327	_sig_add;
		1328	}
		1329
		1330	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1331	}
		1332
1064	sub signal {	1333	sub signal {
1065	my (undef, %arg) = @_;	1334	# probe for availability of Async::Interrupt
		1335	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1336	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1066		1337
1067	unless ($SIGPIPE_R) {	1338	$HAVE_ASYNC_INTERRUPT = 1;
		1339	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1340	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1341
		1342	} else {
		1343	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1344
		1345	require Fcntl;
		1346
1068	if (AnyEvent::WIN32) {	1347	if (AnyEvent::WIN32) {
		1348	require AnyEvent::Util;
		1349
1069	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();	1350	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
1070	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;	1351	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
1071	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case	1352	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1072	} else {	1353	} else {
1073	pipe $SIGPIPE_R, $SIGPIPE_W;	1354	pipe $SIGPIPE_R, $SIGPIPE_W;
1074	require Fcntl;
1075	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1355	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1076	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1356	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1357
		1358	# not strictly required, as $^F is normally 2, but let's make sure...
		1359	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1360	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1077	}	1361	}
1078		1362
1079	$SIGPIPE_R	1363	$SIGPIPE_R
1080	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1364	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1081		1365
1082	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1366	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1083	}	1367	}
1084		1368
1085	my $signal = uc $arg{signal}	1369	*signal = \&_signal;
1086	or Carp::croak "required option 'signal' is missing";	1370	&signal
1087
1088	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1089	$SIG{$signal} ||= sub {
1090	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1091	undef $SIG_EV{$signal};
1092	};
1093
1094	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
1095	}	1371	}
1096		1372
1097	sub AnyEvent::Base::Signal::DESTROY {	1373	sub AnyEvent::Base::signal::DESTROY {
1098	my ($signal, $cb) = @{$_[0]};	1374	my ($signal, $cb) = @{$_[0]};
1099		1375
		1376	_sig_del;
		1377
1100	delete $SIG_CB{$signal}{$cb};	1378	delete $SIG_CB{$signal}{$cb};
1101		1379
		1380	$HAVE_ASYNC_INTERRUPT
		1381	? delete $SIG_ASY{$signal}
		1382	: # delete doesn't work with older perls - they then
		1383	# print weird messages, or just unconditionally exit
		1384	# instead of getting the default action.
		1385	undef $SIG{$signal}
1102	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1386	unless keys %{ $SIG_CB{$signal} };
1103	}	1387	}
1104		1388
1105	# default implementation for ->child	1389	# default implementation for ->child
1106		1390
1107	our %PID_CB;	1391	our %PID_CB;
1108	our $CHLD_W;	1392	our $CHLD_W;
1109	our $CHLD_DELAY_W;	1393	our $CHLD_DELAY_W;
1110	our $PID_IDLE;
1111	our $WNOHANG;	1394	our $WNOHANG;
1112		1395
1113	sub _child_wait {	1396	sub _sigchld {
1114	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1397	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1398	$_->($pid, $?)
1115	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1399	for values %{ $PID_CB{$pid} || {} },
1116	(values %{ $PID_CB{0} || {} });	1400	values %{ $PID_CB{0} || {} };
1117	}	1401	}
1118
1119	undef $PID_IDLE;
1120	}
1121
1122	sub _sigchld {
1123	# make sure we deliver these changes "synchronous" with the event loop.
1124	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1125	undef $CHLD_DELAY_W;
1126	&_child_wait;
1127	});
1128	}	1402	}
1129		1403
1130	sub child {	1404	sub child {
1131	my (undef, %arg) = @_;	1405	my (undef, %arg) = @_;
1132		1406
1133	defined (my $pid = $arg{pid} + 0)	1407	defined (my $pid = $arg{pid} + 0)
1134	or Carp::croak "required option 'pid' is missing";	1408	or Carp::croak "required option 'pid' is missing";
1135		1409
1136	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1410	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1137		1411
1138	unless ($WNOHANG) {	1412	# WNOHANG is almost cetrainly 1 everywhere
		1413	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1414	? 1
1139	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1415	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1140	}
1141		1416
1142	unless ($CHLD_W) {	1417	unless ($CHLD_W) {
1143	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1418	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1144	# child could be a zombie already, so make at least one round	1419	# child could be a zombie already, so make at least one round
1145	&_sigchld;	1420	&_sigchld;
1146	}	1421	}
1147		1422
1148	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1423	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1149	}	1424	}
1150		1425
1151	sub AnyEvent::Base::Child::DESTROY {	1426	sub AnyEvent::Base::child::DESTROY {
1152	my ($pid, $cb) = @{$_[0]};	1427	my ($pid, $cb) = @{$_[0]};
1153		1428
1154	delete $PID_CB{$pid}{$cb};	1429	delete $PID_CB{$pid}{$cb};
1155	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1430	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1156		1431
1157	undef $CHLD_W unless keys %PID_CB;	1432	undef $CHLD_W unless keys %PID_CB;
1158	}	1433	}
1159		1434
		1435	# idle emulation is done by simply using a timer, regardless
		1436	# of whether the process is idle or not, and not letting
		1437	# the callback use more than 50% of the time.
		1438	sub idle {
		1439	my (undef, %arg) = @_;
		1440
		1441	my ($cb, $w, $rcb) = $arg{cb};
		1442
		1443	$rcb = sub {
		1444	if ($cb) {
		1445	$w = _time;
		1446	&$cb;
		1447	$w = _time - $w;
		1448
		1449	# never use more then 50% of the time for the idle watcher,
		1450	# within some limits
		1451	$w = 0.0001 if $w < 0.0001;
		1452	$w = 5 if $w > 5;
		1453
		1454	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1455	} else {
		1456	# clean up...
		1457	undef $w;
		1458	undef $rcb;
		1459	}
		1460	};
		1461
		1462	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1463
		1464	bless \\$cb, "AnyEvent::Base::idle"
		1465	}
		1466
		1467	sub AnyEvent::Base::idle::DESTROY {
		1468	undef $${$_[0]};
		1469	}
		1470
1160	package AnyEvent::CondVar;	1471	package AnyEvent::CondVar;
1161		1472
1162	our @ISA = AnyEvent::CondVar::Base::;	1473	our @ISA = AnyEvent::CondVar::Base::;
1163		1474
1164	package AnyEvent::CondVar::Base;	1475	package AnyEvent::CondVar::Base;
1165		1476
1166	use overload	1477	#use overload
1167	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1478	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1168	fallback => 1;	1479	# fallback => 1;
		1480
		1481	# save 300+ kilobytes by dirtily hardcoding overloading
		1482	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1483	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1484	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1485	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1486
		1487	our $WAITING;
1169		1488
1170	sub _send {	1489	sub _send {
1171	# nop	1490	# nop
1172	}	1491	}
1173		1492
…		…
1186	sub ready {	1505	sub ready {
1187	$_[0]{_ae_sent}	1506	$_[0]{_ae_sent}
1188	}	1507	}
1189		1508
1190	sub _wait {	1509	sub _wait {
		1510	$WAITING
		1511	and !$_[0]{_ae_sent}
		1512	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1513
		1514	local $WAITING = 1;
1191	AnyEvent->one_event while !$_[0]{_ae_sent};	1515	AnyEvent->one_event while !$_[0]{_ae_sent};
1192	}	1516	}
1193		1517
1194	sub recv {	1518	sub recv {
1195	$_[0]->_wait;	1519	$_[0]->_wait;
…		…
1236	so on.	1560	so on.
1237		1561
1238	=head1 ENVIRONMENT VARIABLES	1562	=head1 ENVIRONMENT VARIABLES
1239		1563
1240	The following environment variables are used by this module or its	1564	The following environment variables are used by this module or its
1241	submodules:	1565	submodules.
		1566
		1567	Note that AnyEvent will remove I<all> environment variables starting with
		1568	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1569	enabled.
1242		1570
1243	=over 4	1571	=over 4
1244		1572
1245	=item C<PERL_ANYEVENT_VERBOSE>	1573	=item C<PERL_ANYEVENT_VERBOSE>
1246		1574
…		…
1253	C<PERL_ANYEVENT_MODEL>.	1581	C<PERL_ANYEVENT_MODEL>.
1254		1582
1255	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1583	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1256	model it chooses.	1584	model it chooses.
1257		1585
		1586	When set to C<8> or higher, then AnyEvent will report extra information on
		1587	which optional modules it loads and how it implements certain features.
		1588
1258	=item C<PERL_ANYEVENT_STRICT>	1589	=item C<PERL_ANYEVENT_STRICT>
1259		1590
1260	AnyEvent does not do much argument checking by default, as thorough	1591	AnyEvent does not do much argument checking by default, as thorough
1261	argument checking is very costly. Setting this variable to a true value	1592	argument checking is very costly. Setting this variable to a true value
1262	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1593	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1263	check the arguments passed to most method calls. If it finds any problems	1594	check the arguments passed to most method calls. If it finds any problems,
1264	it will croak.	1595	it will croak.
1265		1596
1266	In other words, enables "strict" mode.	1597	In other words, enables "strict" mode.
1267		1598
1268	Unlike C<use strict>, it is definitely recommended ot keep it off in	1599	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
1269	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1600	>>, it is definitely recommended to keep it off in production. Keeping
1270	developing programs can be very useful, however.	1601	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1602	can be very useful, however.
1271		1603
1272	=item C<PERL_ANYEVENT_MODEL>	1604	=item C<PERL_ANYEVENT_MODEL>
1273		1605
1274	This can be used to specify the event model to be used by AnyEvent, before	1606	This can be used to specify the event model to be used by AnyEvent, before
1275	auto detection and -probing kicks in. It must be a string consisting	1607	auto detection and -probing kicks in. It must be a string consisting
…		…
1318		1650
1319	=item C<PERL_ANYEVENT_MAX_FORKS>	1651	=item C<PERL_ANYEVENT_MAX_FORKS>
1320		1652
1321	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1653	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1322	will create in parallel.	1654	will create in parallel.
		1655
		1656	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1657
		1658	The default value for the C<max_outstanding> parameter for the default DNS
		1659	resolver - this is the maximum number of parallel DNS requests that are
		1660	sent to the DNS server.
		1661
		1662	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1663
		1664	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1665	configuration) in the default resolver. When set to the empty string, no
		1666	default config will be used.
		1667
		1668	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1669
		1670	When neither C<ca_file> nor C<ca_path> was specified during
		1671	L<AnyEvent::TLS> context creation, and either of these environment
		1672	variables exist, they will be used to specify CA certificate locations
		1673	instead of a system-dependent default.
		1674
		1675	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1676
		1677	When these are set to C<1>, then the respective modules are not
		1678	loaded. Mostly good for testing AnyEvent itself.
1323		1679
1324	=back	1680	=back
1325		1681
1326	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1682	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1327		1683
…		…
1572	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	1928	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1573	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	1929	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1574	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	1930	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1575	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	1931	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1576	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	1932	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1933	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1934	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1577	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	1935	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1578	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	1936	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1579	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	1937	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1580	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	1938	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1581		1939
…		…
1610	performance becomes really bad with lots of file descriptors (and few of	1968	performance becomes really bad with lots of file descriptors (and few of
1611	them active), of course, but this was not subject of this benchmark.	1969	them active), of course, but this was not subject of this benchmark.
1612		1970
1613	The C<Event> module has a relatively high setup and callback invocation	1971	The C<Event> module has a relatively high setup and callback invocation
1614	cost, but overall scores in on the third place.	1972	cost, but overall scores in on the third place.
		1973
		1974	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1975	when using its pure perl backend.
1615		1976
1616	C<Glib>'s memory usage is quite a bit higher, but it features a	1977	C<Glib>'s memory usage is quite a bit higher, but it features a
1617	faster callback invocation and overall ends up in the same class as	1978	faster callback invocation and overall ends up in the same class as
1618	C<Event>. However, Glib scales extremely badly, doubling the number of	1979	C<Event>. However, Glib scales extremely badly, doubling the number of
1619	watchers increases the processing time by more than a factor of four,	1980	watchers increases the processing time by more than a factor of four,
…		…
1697	it to another server. This includes deleting the old timeout and creating	2058	it to another server. This includes deleting the old timeout and creating
1698	a new one that moves the timeout into the future.	2059	a new one that moves the timeout into the future.
1699		2060
1700	=head3 Results	2061	=head3 Results
1701		2062
1702	name sockets create request	2063	name sockets create request
1703	EV 20000 69.01 11.16	2064	EV 20000 69.01 11.16
1704	Perl 20000 73.32 35.87	2065	Perl 20000 73.32 35.87
		2066	IOAsync 20000 157.00 98.14 epoll
		2067	IOAsync 20000 159.31 616.06 poll
1705	Event 20000 212.62 257.32	2068	Event 20000 212.62 257.32
1706	Glib 20000 651.16 1896.30	2069	Glib 20000 651.16 1896.30
1707	POE 20000 349.67 12317.24 uses POE::Loop::Event	2070	POE 20000 349.67 12317.24 uses POE::Loop::Event
1708		2071
1709	=head3 Discussion	2072	=head3 Discussion
1710		2073
1711	This benchmark I<does> measure scalability and overall performance of the	2074	This benchmark I<does> measure scalability and overall performance of the
1712	particular event loop.	2075	particular event loop.
…		…
1714	EV is again fastest. Since it is using epoll on my system, the setup time	2077	EV is again fastest. Since it is using epoll on my system, the setup time
1715	is relatively high, though.	2078	is relatively high, though.
1716		2079
1717	Perl surprisingly comes second. It is much faster than the C-based event	2080	Perl surprisingly comes second. It is much faster than the C-based event
1718	loops Event and Glib.	2081	loops Event and Glib.
		2082
		2083	IO::Async performs very well when using its epoll backend, and still quite
		2084	good compared to Glib when using its pure perl backend.
1719		2085
1720	Event suffers from high setup time as well (look at its code and you will	2086	Event suffers from high setup time as well (look at its code and you will
1721	understand why). Callback invocation also has a high overhead compared to	2087	understand why). Callback invocation also has a high overhead compared to
1722	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2088	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1723	uses select or poll in basically all documented configurations.	2089	uses select or poll in basically all documented configurations.
…		…
1786	=item * C-based event loops perform very well with small number of	2152	=item * C-based event loops perform very well with small number of
1787	watchers, as the management overhead dominates.	2153	watchers, as the management overhead dominates.
1788		2154
1789	=back	2155	=back
1790		2156
		2157	=head2 THE IO::Lambda BENCHMARK
		2158
		2159	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2160	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2161	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2162	shouldn't come as a surprise to anybody). As such, the benchmark is
		2163	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2164	very optimal. But how would AnyEvent compare when used without the extra
		2165	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2166
		2167	The benchmark itself creates an echo-server, and then, for 500 times,
		2168	connects to the echo server, sends a line, waits for the reply, and then
		2169	creates the next connection. This is a rather bad benchmark, as it doesn't
		2170	test the efficiency of the framework or much non-blocking I/O, but it is a
		2171	benchmark nevertheless.
		2172
		2173	name runtime
		2174	Lambda/select 0.330 sec
		2175	+ optimized 0.122 sec
		2176	Lambda/AnyEvent 0.327 sec
		2177	+ optimized 0.138 sec
		2178	Raw sockets/select 0.077 sec
		2179	POE/select, components 0.662 sec
		2180	POE/select, raw sockets 0.226 sec
		2181	POE/select, optimized 0.404 sec
		2182
		2183	AnyEvent/select/nb 0.085 sec
		2184	AnyEvent/EV/nb 0.068 sec
		2185	+state machine 0.134 sec
		2186
		2187	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2188	benchmarks actually make blocking connects and use 100% blocking I/O,
		2189	defeating the purpose of an event-based solution. All of the newly
		2190	written AnyEvent benchmarks use 100% non-blocking connects (using
		2191	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2192	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2193	generally require a lot more bookkeeping and event handling than blocking
		2194	connects (which involve a single syscall only).
		2195
		2196	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2197	offers similar expressive power as POE and IO::Lambda, using conventional
		2198	Perl syntax. This means that both the echo server and the client are 100%
		2199	non-blocking, further placing it at a disadvantage.
		2200
		2201	As you can see, the AnyEvent + EV combination even beats the
		2202	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2203	backend easily beats IO::Lambda and POE.
		2204
		2205	And even the 100% non-blocking version written using the high-level (and
		2206	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2207	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2208	in a non-blocking way.
		2209
		2210	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2211	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2212	part of the IO::lambda distribution and were used without any changes.
		2213
1791		2214
1792	=head1 SIGNALS	2215	=head1 SIGNALS
1793		2216
1794	AnyEvent currently installs handlers for these signals:	2217	AnyEvent currently installs handlers for these signals:
1795		2218
…		…
1798	=item SIGCHLD	2221	=item SIGCHLD
1799		2222
1800	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2223	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1801	emulation for event loops that do not support them natively. Also, some	2224	emulation for event loops that do not support them natively. Also, some
1802	event loops install a similar handler.	2225	event loops install a similar handler.
		2226
		2227	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2228	AnyEvent will reset it to default, to avoid losing child exit statuses.
1803		2229
1804	=item SIGPIPE	2230	=item SIGPIPE
1805		2231
1806	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2232	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1807	when AnyEvent gets loaded.	2233	when AnyEvent gets loaded.
…		…
1819		2245
1820	=back	2246	=back
1821		2247
1822	=cut	2248	=cut
1823		2249
		2250	undef $SIG{CHLD}
		2251	if $SIG{CHLD} eq 'IGNORE';
		2252
1824	$SIG{PIPE} = sub { }	2253	$SIG{PIPE} = sub { }
1825	unless defined $SIG{PIPE};	2254	unless defined $SIG{PIPE};
		2255
		2256	=head1 RECOMMENDED/OPTIONAL MODULES
		2257
		2258	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2259	it's built-in modules) are required to use it.
		2260
		2261	That does not mean that AnyEvent won't take advantage of some additional
		2262	modules if they are installed.
		2263
		2264	This section epxlains which additional modules will be used, and how they
		2265	affect AnyEvent's operetion.
		2266
		2267	=over 4
		2268
		2269	=item L<Async::Interrupt>
		2270
		2271	This slightly arcane module is used to implement fast signal handling: To
		2272	my knowledge, there is no way to do completely race-free and quick
		2273	signal handling in pure perl. To ensure that signals still get
		2274	delivered, AnyEvent will start an interval timer to wake up perl (and
		2275	catch the signals) with soemd elay (default is 10 seconds, look for
		2276	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2277
		2278	If this module is available, then it will be used to implement signal
		2279	catching, which means that signals will not be delayed, and the event loop
		2280	will not be interrupted regularly, which is more efficient (And good for
		2281	battery life on laptops).
		2282
		2283	This affects not just the pure-perl event loop, but also other event loops
		2284	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2285
		2286	=item L<EV>
		2287
		2288	This module isn't really "optional", as it is simply one of the backend
		2289	event loops that AnyEvent can use. However, it is simply the best event
		2290	loop available in terms of features, speed and stability: It supports
		2291	the AnyEvent API optimally, implements all the watcher types in XS, does
		2292	automatic timer adjustments even when no monotonic clock is available,
		2293	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2294	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2295	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2296
		2297	=item L<Guard>
		2298
		2299	The guard module, when used, will be used to implement
		2300	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2301	lot less memory), but otherwise doesn't affect guard operation much. It is
		2302	purely used for performance.
		2303
		2304	=item L<JSON> and L<JSON::XS>
		2305
		2306	This module is required when you want to read or write JSON data via
		2307	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2308	advantage of the ulta-high-speed L<JSON::XS> module when it is installed.
		2309
		2310	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2311	installed.
		2312
		2313	=item L<Net::SSLeay>
		2314
		2315	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2316	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2317	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2318
		2319	=item L<Time::HiRes>
		2320
		2321	This module is part of perl since release 5.008. It will be used when the
		2322	chosen event library does not come with a timing source on it's own. The
		2323	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2324	try to use a monotonic clock for timing stability.
		2325
		2326	=back
1826		2327
1827		2328
1828	=head1 FORK	2329	=head1 FORK
1829		2330
1830	Most event libraries are not fork-safe. The ones who are usually are	2331	Most event libraries are not fork-safe. The ones who are usually are
1831	because they rely on inefficient but fork-safe C<select> or C<poll>	2332	because they rely on inefficient but fork-safe C<select> or C<poll>
1832	calls. Only L<EV> is fully fork-aware.	2333	calls. Only L<EV> is fully fork-aware.
1833		2334
1834	If you have to fork, you must either do so I<before> creating your first	2335	If you have to fork, you must either do so I<before> creating your first
1835	watcher OR you must not use AnyEvent at all in the child.	2336	watcher OR you must not use AnyEvent at all in the child OR you must do
		2337	something completely out of the scope of AnyEvent.
1836		2338
1837		2339
1838	=head1 SECURITY CONSIDERATIONS	2340	=head1 SECURITY CONSIDERATIONS
1839		2341
1840	AnyEvent can be forced to load any event model via	2342	AnyEvent can be forced to load any event model via
…		…
1852	use AnyEvent;	2354	use AnyEvent;
1853		2355
1854	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2356	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1855	be used to probe what backend is used and gain other information (which is	2357	be used to probe what backend is used and gain other information (which is
1856	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2358	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1857	$ENV{PERL_ANYEGENT_STRICT}.	2359	$ENV{PERL_ANYEVENT_STRICT}.
		2360
		2361	Note that AnyEvent will remove I<all> environment variables starting with
		2362	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2363	enabled.
1858		2364
1859		2365
1860	=head1 BUGS	2366	=head1 BUGS
1861		2367
1862	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2368	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1863	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2369	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1864	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2370	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1865	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2371	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1866	pronounced).	2372	pronounced).
1867		2373
1868		2374
1869	=head1 SEE ALSO	2375	=head1 SEE ALSO
1870		2376
…		…
1874	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2380	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1875		2381
1876	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2382	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1877	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2383	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1878	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2384	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1879	L<AnyEvent::Impl::POE>.	2385	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1880		2386
1881	Non-blocking file handles, sockets, TCP clients and	2387	Non-blocking file handles, sockets, TCP clients and
1882	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2388	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1883		2389
1884	Asynchronous DNS: L<AnyEvent::DNS>.	2390	Asynchronous DNS: L<AnyEvent::DNS>.
1885		2391
1886	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2392	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2393	L<Coro::Event>,
1887		2394
1888	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2395	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2396	L<AnyEvent::HTTP>.
1889		2397
1890		2398
1891	=head1 AUTHOR	2399	=head1 AUTHOR
1892		2400
1893	Marc Lehmann <schmorp@schmorp.de>	2401	Marc Lehmann <schmorp@schmorp.de>

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