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Revision 1.200 by root, Wed Apr 1 14:02:27 2009 UTC vs.
Revision 1.247 by root, Sat Jul 18 22:24:17 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> is the Perl I<file handle> (I<not> file descriptor) to watch	181	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	182	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	183	handle). Note that only file handles pointing to things for which
176	non-blocking operation makes sense are allowed. This includes sockets,	184	non-blocking operation makes sense are allowed. This includes sockets,
177	most character devices, pipes, fifos and so on, but not for example files	185	most character devices, pipes, fifos and so on, but not for example files
178	or block devices.	186	or block devices.
…		…
320	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
321	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
322	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
323	account.	331	account.
324		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
325	=back	348	=back
326		349
327	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
328		351
329	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
…		…
338	invocation, and callback invocation will be synchronous. Synchronous means	361	invocation, and callback invocation will be synchronous. Synchronous means
339	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,
340	but it is guaranteed not to interrupt any other callbacks.	363	but it is guaranteed not to interrupt any other callbacks.
341		364
342	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
343	between multiple watchers.	366	between multiple watchers, and AnyEvent will ensure that signals will not
		367	interrupt your program at bad times.
344		368
345	This watcher might use C<%SIG>, so programs overwriting those signals	369	This watcher might use C<%SIG> (depending on the event loop used),
346	directly will likely not work correctly.	370	so programs overwriting those signals directly will likely not work
		371	correctly.
347		372
348	Example: exit on SIGINT	373	Example: exit on SIGINT
349		374
350	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	375	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
		376
		377	=head3 Signal Races, Delays and Workarounds
		378
		379	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		380	callbacks to signals in a generic way, which is a pity, as you cannot do
		381	race-free signal handling in perl. AnyEvent will try to do it's best, but
		382	in some cases, signals will be delayed. The maximum time a signal might
		383	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		384	seconds). This variable can be changed only before the first signal
		385	watcher is created, and should be left alone otherwise. Higher values
		386	will cause fewer spurious wake-ups, which is better for power and CPU
		387	saving. All these problems can be avoided by installing the optional
		388	L<Async::Interrupt> module. This will not work with inherently broken
		389	event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
		390	currently, as POE does it's own workaround with one-second latency). With
		391	those, you just have to suffer the delays.
351		392
352	=head2 CHILD PROCESS WATCHERS	393	=head2 CHILD PROCESS WATCHERS
353		394
354	You can also watch on a child process exit and catch its exit status.	395	You can also watch on a child process exit and catch its exit status.
355		396
…		…
369		410
370	There is a slight catch to child watchers, however: you usually start them	411	There is a slight catch to child watchers, however: you usually start them
371	I<after> the child process was created, and this means the process could	412	I<after> the child process was created, and this means the process could
372	have exited already (and no SIGCHLD will be sent anymore).	413	have exited already (and no SIGCHLD will be sent anymore).
373		414
374	Not all event models handle this correctly (POE doesn't), but even for	415	Not all event models handle this correctly (neither POE nor IO::Async do,
		416	see their AnyEvent::Impl manpages for details), but even for event models
375	event models that I<do> handle this correctly, they usually need to be	417	that I<do> handle this correctly, they usually need to be loaded before
376	loaded before the process exits (i.e. before you fork in the first place).	418	the process exits (i.e. before you fork in the first place). AnyEvent's
		419	pure perl event loop handles all cases correctly regardless of when you
		420	start the watcher.
377		421
378	This means you cannot create a child watcher as the very first thing in an	422	This means you cannot create a child watcher as the very first
379	AnyEvent program, you I<have> to create at least one watcher before you	423	thing in an AnyEvent program, you I<have> to create at least one
380	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	424	watcher before you C<fork> the child (alternatively, you can call
		425	C<AnyEvent::detect>).
		426
		427	As most event loops do not support waiting for child events, they will be
		428	emulated by AnyEvent in most cases, in which the latency and race problems
		429	mentioned in the description of signal watchers apply.
381		430
382	Example: fork a process and wait for it	431	Example: fork a process and wait for it
383		432
384	my $done = AnyEvent->condvar;	433	my $done = AnyEvent->condvar;
385		434
…		…
395	);	444	);
396		445
397	# do something else, then wait for process exit	446	# do something else, then wait for process exit
398	$done->recv;	447	$done->recv;
399		448
		449	=head2 IDLE WATCHERS
		450
		451	Sometimes there is a need to do something, but it is not so important
		452	to do it instantly, but only when there is nothing better to do. This
		453	"nothing better to do" is usually defined to be "no other events need
		454	attention by the event loop".
		455
		456	Idle watchers ideally get invoked when the event loop has nothing
		457	better to do, just before it would block the process to wait for new
		458	events. Instead of blocking, the idle watcher is invoked.
		459
		460	Most event loops unfortunately do not really support idle watchers (only
		461	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		462	will simply call the callback "from time to time".
		463
		464	Example: read lines from STDIN, but only process them when the
		465	program is otherwise idle:
		466
		467	my @lines; # read data
		468	my $idle_w;
		469	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		470	push @lines, scalar <STDIN>;
		471
		472	# start an idle watcher, if not already done
		473	$idle_w ||= AnyEvent->idle (cb => sub {
		474	# handle only one line, when there are lines left
		475	if (my $line = shift @lines) {
		476	print "handled when idle: $line";
		477	} else {
		478	# otherwise disable the idle watcher again
		479	undef $idle_w;
		480	}
		481	});
		482	});
		483
400	=head2 CONDITION VARIABLES	484	=head2 CONDITION VARIABLES
401		485
402	If you are familiar with some event loops you will know that all of them	486	If you are familiar with some event loops you will know that all of them
403	require you to run some blocking "loop", "run" or similar function that	487	require you to run some blocking "loop", "run" or similar function that
404	will actively watch for new events and call your callbacks.	488	will actively watch for new events and call your callbacks.
405		489
406	AnyEvent is different, it expects somebody else to run the event loop and	490	AnyEvent is slightly different: it expects somebody else to run the event
407	will only block when necessary (usually when told by the user).	491	loop and will only block when necessary (usually when told by the user).
408		492
409	The instrument to do that is called a "condition variable", so called	493	The instrument to do that is called a "condition variable", so called
410	because they represent a condition that must become true.	494	because they represent a condition that must become true.
411		495
		496	Now is probably a good time to look at the examples further below.
		497
412	Condition variables can be created by calling the C<< AnyEvent->condvar	498	Condition variables can be created by calling the C<< AnyEvent->condvar
413	>> method, usually without arguments. The only argument pair allowed is	499	>> method, usually without arguments. The only argument pair allowed is
414
415	C<cb>, which specifies a callback to be called when the condition variable	500	C<cb>, which specifies a callback to be called when the condition variable
416	becomes true, with the condition variable as the first argument (but not	501	becomes true, with the condition variable as the first argument (but not
417	the results).	502	the results).
418		503
419	After creation, the condition variable is "false" until it becomes "true"	504	After creation, the condition variable is "false" until it becomes "true"
…		…
468	after => 1,	553	after => 1,
469	cb => sub { $result_ready->send },	554	cb => sub { $result_ready->send },
470	);	555	);
471		556
472	# this "blocks" (while handling events) till the callback	557	# this "blocks" (while handling events) till the callback
473	# calls send	558	# calls -<send
474	$result_ready->recv;	559	$result_ready->recv;
475		560
476	Example: wait for a timer, but take advantage of the fact that	561	Example: wait for a timer, but take advantage of the fact that condition
477	condition variables are also code references.	562	variables are also callable directly.
478		563
479	my $done = AnyEvent->condvar;	564	my $done = AnyEvent->condvar;
480	my $delay = AnyEvent->timer (after => 5, cb => $done);	565	my $delay = AnyEvent->timer (after => 5, cb => $done);
481	$done->recv;	566	$done->recv;
482		567
…		…
488		573
489	...	574	...
490		575
491	my @info = $couchdb->info->recv;	576	my @info = $couchdb->info->recv;
492		577
493	And this is how you would just ste a callback to be called whenever the	578	And this is how you would just set a callback to be called whenever the
494	results are available:	579	results are available:
495		580
496	$couchdb->info->cb (sub {	581	$couchdb->info->cb (sub {
497	my @info = $_[0]->recv;	582	my @info = $_[0]->recv;
498	});	583	});
…		…
516	immediately from within send.	601	immediately from within send.
517		602
518	Any arguments passed to the C<send> call will be returned by all	603	Any arguments passed to the C<send> call will be returned by all
519	future C<< ->recv >> calls.	604	future C<< ->recv >> calls.
520		605
521	Condition variables are overloaded so one can call them directly	606	Condition variables are overloaded so one can call them directly (as if
522	(as a code reference). Calling them directly is the same as calling	607	they were a code reference). Calling them directly is the same as calling
523	C<send>. Note, however, that many C-based event loops do not handle	608	C<send>.
524	overloading, so as tempting as it may be, passing a condition variable
525	instead of a callback does not work. Both the pure perl and EV loops
526	support overloading, however, as well as all functions that use perl to
527	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
528	example).
529		609
530	=item $cv->croak ($error)	610	=item $cv->croak ($error)
531		611
532	Similar to send, but causes all call's to C<< ->recv >> to invoke	612	Similar to send, but causes all call's to C<< ->recv >> to invoke
533	C<Carp::croak> with the given error message/object/scalar.	613	C<Carp::croak> with the given error message/object/scalar.
534		614
535	This can be used to signal any errors to the condition variable	615	This can be used to signal any errors to the condition variable
536	user/consumer.	616	user/consumer. Doing it this way instead of calling C<croak> directly
		617	delays the error detetcion, but has the overwhelmign advantage that it
		618	diagnoses the error at the place where the result is expected, and not
		619	deep in some event clalback without connection to the actual code causing
		620	the problem.
537		621
538	=item $cv->begin ([group callback])	622	=item $cv->begin ([group callback])
539		623
540	=item $cv->end	624	=item $cv->end
541
542	These two methods are EXPERIMENTAL and MIGHT CHANGE.
543		625
544	These two methods can be used to combine many transactions/events into	626	These two methods can be used to combine many transactions/events into
545	one. For example, a function that pings many hosts in parallel might want	627	one. For example, a function that pings many hosts in parallel might want
546	to use a condition variable for the whole process.	628	to use a condition variable for the whole process.
547		629
…		…
549	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	631	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
550	>>, the (last) callback passed to C<begin> will be executed. That callback	632	>>, the (last) callback passed to C<begin> will be executed. That callback
551	is I<supposed> to call C<< ->send >>, but that is not required. If no	633	is I<supposed> to call C<< ->send >>, but that is not required. If no
552	callback was set, C<send> will be called without any arguments.	634	callback was set, C<send> will be called without any arguments.
553		635
554	Let's clarify this with the ping example:	636	You can think of C<< $cv->send >> giving you an OR condition (one call
		637	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		638	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		639
		640	Let's start with a simple example: you have two I/O watchers (for example,
		641	STDOUT and STDERR for a program), and you want to wait for both streams to
		642	close before activating a condvar:
		643
		644	my $cv = AnyEvent->condvar;
		645
		646	$cv->begin; # first watcher
		647	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		648	defined sysread $fh1, my $buf, 4096
		649	or $cv->end;
		650	});
		651
		652	$cv->begin; # second watcher
		653	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		654	defined sysread $fh2, my $buf, 4096
		655	or $cv->end;
		656	});
		657
		658	$cv->recv;
		659
		660	This works because for every event source (EOF on file handle), there is
		661	one call to C<begin>, so the condvar waits for all calls to C<end> before
		662	sending.
		663
		664	The ping example mentioned above is slightly more complicated, as the
		665	there are results to be passwd back, and the number of tasks that are
		666	begung can potentially be zero:
555		667
556	my $cv = AnyEvent->condvar;	668	my $cv = AnyEvent->condvar;
557		669
558	my %result;	670	my %result;
559	$cv->begin (sub { $cv->send (\%result) });	671	$cv->begin (sub { $cv->send (\%result) });
…		…
579	loop, which serves two important purposes: first, it sets the callback	691	loop, which serves two important purposes: first, it sets the callback
580	to be called once the counter reaches C<0>, and second, it ensures that	692	to be called once the counter reaches C<0>, and second, it ensures that
581	C<send> is called even when C<no> hosts are being pinged (the loop	693	C<send> is called even when C<no> hosts are being pinged (the loop
582	doesn't execute once).	694	doesn't execute once).
583		695
584	This is the general pattern when you "fan out" into multiple subrequests:	696	This is the general pattern when you "fan out" into multiple (but
585	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	697	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
586	is called at least once, and then, for each subrequest you start, call	698	the callback and ensure C<end> is called at least once, and then, for each
587	C<begin> and for each subrequest you finish, call C<end>.	699	subrequest you start, call C<begin> and for each subrequest you finish,
		700	call C<end>.
588		701
589	=back	702	=back
590		703
591	=head3 METHODS FOR CONSUMERS	704	=head3 METHODS FOR CONSUMERS
592		705
…		…
608	function will call C<croak>.	721	function will call C<croak>.
609		722
610	In list context, all parameters passed to C<send> will be returned,	723	In list context, all parameters passed to C<send> will be returned,
611	in scalar context only the first one will be returned.	724	in scalar context only the first one will be returned.
612		725
		726	Note that doing a blocking wait in a callback is not supported by any
		727	event loop, that is, recursive invocation of a blocking C<< ->recv
		728	>> is not allowed, and the C<recv> call will C<croak> if such a
		729	condition is detected. This condition can be slightly loosened by using
		730	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		731	any thread that doesn't run the event loop itself.
		732
613	Not all event models support a blocking wait - some die in that case	733	Not all event models support a blocking wait - some die in that case
614	(programs might want to do that to stay interactive), so I<if you are	734	(programs might want to do that to stay interactive), so I<if you are
615	using this from a module, never require a blocking wait>, but let the	735	using this from a module, never require a blocking wait>. Instead, let the
616	caller decide whether the call will block or not (for example, by coupling	736	caller decide whether the call will block or not (for example, by coupling
617	condition variables with some kind of request results and supporting	737	condition variables with some kind of request results and supporting
618	callbacks so the caller knows that getting the result will not block,	738	callbacks so the caller knows that getting the result will not block,
619	while still supporting blocking waits if the caller so desires).	739	while still supporting blocking waits if the caller so desires).
620		740
621	Another reason I<never> to C<< ->recv >> in a module is that you cannot
622	sensibly have two C<< ->recv >>'s in parallel, as that would require
623	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
624	can supply.
625
626	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
627	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
628	versions and also integrates coroutines into AnyEvent, making blocking
629	C<< ->recv >> calls perfectly safe as long as they are done from another
630	coroutine (one that doesn't run the event loop).
631
632	You can ensure that C<< -recv >> never blocks by setting a callback and	741	You can ensure that C<< -recv >> never blocks by setting a callback and
633	only calling C<< ->recv >> from within that callback (or at a later	742	only calling C<< ->recv >> from within that callback (or at a later
634	time). This will work even when the event loop does not support blocking	743	time). This will work even when the event loop does not support blocking
635	waits otherwise.	744	waits otherwise.
636		745
…		…
649	variable itself. Calling C<recv> inside the callback or at any later time	758	variable itself. Calling C<recv> inside the callback or at any later time
650	is guaranteed not to block.	759	is guaranteed not to block.
651		760
652	=back	761	=back
653		762
		763	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		764
		765	The available backend classes are (every class has its own manpage):
		766
		767	=over 4
		768
		769	=item Backends that are autoprobed when no other event loop can be found.
		770
		771	EV is the preferred backend when no other event loop seems to be in
		772	use. If EV is not installed, then AnyEvent will try Event, and, failing
		773	that, will fall back to its own pure-perl implementation, which is
		774	available everywhere as it comes with AnyEvent itself.
		775
		776	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		777	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		778	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		779
		780	=item Backends that are transparently being picked up when they are used.
		781
		782	These will be used when they are currently loaded when the first watcher
		783	is created, in which case it is assumed that the application is using
		784	them. This means that AnyEvent will automatically pick the right backend
		785	when the main program loads an event module before anything starts to
		786	create watchers. Nothing special needs to be done by the main program.
		787
		788	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		789	AnyEvent::Impl::Tk based on Tk, very broken.
		790	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		791	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		792
		793	=item Backends with special needs.
		794
		795	Qt requires the Qt::Application to be instantiated first, but will
		796	otherwise be picked up automatically. As long as the main program
		797	instantiates the application before any AnyEvent watchers are created,
		798	everything should just work.
		799
		800	AnyEvent::Impl::Qt based on Qt.
		801
		802	Support for IO::Async can only be partial, as it is too broken and
		803	architecturally limited to even support the AnyEvent API. It also
		804	is the only event loop that needs the loop to be set explicitly, so
		805	it can only be used by a main program knowing about AnyEvent. See
		806	L<AnyEvent::Impl::Async> for the gory details.
		807
		808	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		809
		810	=item Event loops that are indirectly supported via other backends.
		811
		812	Some event loops can be supported via other modules:
		813
		814	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		815
		816	B<WxWidgets> has no support for watching file handles. However, you can
		817	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		818	polls 20 times per second, which was considered to be too horrible to even
		819	consider for AnyEvent.
		820
		821	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		822	backend, so it can be supported through POE.
		823
		824	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		825	load L<POE> when detecting them, in the hope that POE will pick them up,
		826	in which case everything will be automatic.
		827
		828	=back
		829
654	=head1 GLOBAL VARIABLES AND FUNCTIONS	830	=head1 GLOBAL VARIABLES AND FUNCTIONS
655		831
		832	These are not normally required to use AnyEvent, but can be useful to
		833	write AnyEvent extension modules.
		834
656	=over 4	835	=over 4
657		836
658	=item $AnyEvent::MODEL	837	=item $AnyEvent::MODEL
659		838
660	Contains C<undef> until the first watcher is being created. Then it	839	Contains C<undef> until the first watcher is being created, before the
		840	backend has been autodetected.
		841
661	contains the event model that is being used, which is the name of the	842	Afterwards it contains the event model that is being used, which is the
662	Perl class implementing the model. This class is usually one of the	843	name of the Perl class implementing the model. This class is usually one
663	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	844	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
664	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	845	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
665		846	will be C<urxvt::anyevent>).
666	The known classes so far are:
667
668	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
669	AnyEvent::Impl::Event based on Event, second best choice.
670	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
671	AnyEvent::Impl::Glib based on Glib, third-best choice.
672	AnyEvent::Impl::Tk based on Tk, very bad choice.
673	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
674	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
675	AnyEvent::Impl::POE based on POE, not generic enough for full support.
676
677	There is no support for WxWidgets, as WxWidgets has no support for
678	watching file handles. However, you can use WxWidgets through the
679	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
680	second, which was considered to be too horrible to even consider for
681	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
682	it's adaptor.
683
684	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
685	autodetecting them.
686		847
687	=item AnyEvent::detect	848	=item AnyEvent::detect
688		849
689	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	850	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
690	if necessary. You should only call this function right before you would	851	if necessary. You should only call this function right before you would
691	have created an AnyEvent watcher anyway, that is, as late as possible at	852	have created an AnyEvent watcher anyway, that is, as late as possible at
692	runtime.	853	runtime, and not e.g. while initialising of your module.
		854
		855	If you need to do some initialisation before AnyEvent watchers are
		856	created, use C<post_detect>.
693		857
694	=item $guard = AnyEvent::post_detect { BLOCK }	858	=item $guard = AnyEvent::post_detect { BLOCK }
695		859
696	Arranges for the code block to be executed as soon as the event model is	860	Arranges for the code block to be executed as soon as the event model is
697	autodetected (or immediately if this has already happened).	861	autodetected (or immediately if this has already happened).
		862
		863	The block will be executed I<after> the actual backend has been detected
		864	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		865	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		866	other initialisations - see the sources of L<AnyEvent::Strict> or
		867	L<AnyEvent::AIO> to see how this is used.
		868
		869	The most common usage is to create some global watchers, without forcing
		870	event module detection too early, for example, L<AnyEvent::AIO> creates
		871	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		872	avoid autodetecting the event module at load time.
698		873
699	If called in scalar or list context, then it creates and returns an object	874	If called in scalar or list context, then it creates and returns an object
700	that automatically removes the callback again when it is destroyed. See	875	that automatically removes the callback again when it is destroyed. See
701	L<Coro::BDB> for a case where this is useful.	876	L<Coro::BDB> for a case where this is useful.
702		877
…		…
705	If there are any code references in this array (you can C<push> to it	880	If there are any code references in this array (you can C<push> to it
706	before or after loading AnyEvent), then they will called directly after	881	before or after loading AnyEvent), then they will called directly after
707	the event loop has been chosen.	882	the event loop has been chosen.
708		883
709	You should check C<$AnyEvent::MODEL> before adding to this array, though:	884	You should check C<$AnyEvent::MODEL> before adding to this array, though:
710	if it contains a true value then the event loop has already been detected,	885	if it is defined then the event loop has already been detected, and the
711	and the array will be ignored.	886	array will be ignored.
712		887
713	Best use C<AnyEvent::post_detect { BLOCK }> instead.	888	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		889	it,as it takes care of these details.
		890
		891	This variable is mainly useful for modules that can do something useful
		892	when AnyEvent is used and thus want to know when it is initialised, but do
		893	not need to even load it by default. This array provides the means to hook
		894	into AnyEvent passively, without loading it.
714		895
715	=back	896	=back
716		897
717	=head1 WHAT TO DO IN A MODULE	898	=head1 WHAT TO DO IN A MODULE
718		899
…		…
773		954
774		955
775	=head1 OTHER MODULES	956	=head1 OTHER MODULES
776		957
777	The following is a non-exhaustive list of additional modules that use	958	The following is a non-exhaustive list of additional modules that use
778	AnyEvent and can therefore be mixed easily with other AnyEvent modules	959	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
779	in the same program. Some of the modules come with AnyEvent, some are	960	modules and other event loops in the same program. Some of the modules
780	available via CPAN.	961	come with AnyEvent, most are available via CPAN.
781		962
782	=over 4	963	=over 4
783		964
784	=item L<AnyEvent::Util>	965	=item L<AnyEvent::Util>
785		966
…		…
794		975
795	=item L<AnyEvent::Handle>	976	=item L<AnyEvent::Handle>
796		977
797	Provide read and write buffers, manages watchers for reads and writes,	978	Provide read and write buffers, manages watchers for reads and writes,
798	supports raw and formatted I/O, I/O queued and fully transparent and	979	supports raw and formatted I/O, I/O queued and fully transparent and
799	non-blocking SSL/TLS.	980	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
800		981
801	=item L<AnyEvent::DNS>	982	=item L<AnyEvent::DNS>
802		983
803	Provides rich asynchronous DNS resolver capabilities.	984	Provides rich asynchronous DNS resolver capabilities.
804		985
…		…
832		1013
833	=item L<AnyEvent::GPSD>	1014	=item L<AnyEvent::GPSD>
834		1015
835	A non-blocking interface to gpsd, a daemon delivering GPS information.	1016	A non-blocking interface to gpsd, a daemon delivering GPS information.
836		1017
		1018	=item L<AnyEvent::IRC>
		1019
		1020	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1021
		1022	=item L<AnyEvent::XMPP>
		1023
		1024	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1025	Net::XMPP2>.
		1026
837	=item L<AnyEvent::IGS>	1027	=item L<AnyEvent::IGS>
838		1028
839	A non-blocking interface to the Internet Go Server protocol (used by	1029	A non-blocking interface to the Internet Go Server protocol (used by
840	L<App::IGS>).	1030	L<App::IGS>).
841		1031
842	=item L<AnyEvent::IRC>
843
844	AnyEvent based IRC client module family (replacing the older Net::IRC3).
845
846	=item L<Net::XMPP2>
847
848	AnyEvent based XMPP (Jabber protocol) module family.
849
850	=item L<Net::FCP>	1032	=item L<Net::FCP>
851		1033
852	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1034	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
853	of AnyEvent.	1035	of AnyEvent.
854		1036
…		…
858		1040
859	=item L<Coro>	1041	=item L<Coro>
860		1042
861	Has special support for AnyEvent via L<Coro::AnyEvent>.	1043	Has special support for AnyEvent via L<Coro::AnyEvent>.
862		1044
863	=item L<IO::Lambda>
864
865	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
866
867	=back	1045	=back
868		1046
869	=cut	1047	=cut
870		1048
871	package AnyEvent;	1049	package AnyEvent;
872		1050
		1051	# basically a tuned-down version of common::sense
		1052	sub common_sense {
873	no warnings;	1053	# no warnings
		1054	${^WARNING_BITS} ^= ${^WARNING_BITS};
874	use strict qw(vars subs);	1055	# use strict vars subs
		1056	$^H |= 0x00000600;
		1057	}
875		1058
		1059	BEGIN { AnyEvent::common_sense }
		1060
876	use Carp;	1061	use Carp ();
877		1062
878	our $VERSION = 4.35;	1063	our $VERSION = 4.85;
879	our $MODEL;	1064	our $MODEL;
880		1065
881	our $AUTOLOAD;	1066	our $AUTOLOAD;
882	our @ISA;	1067	our @ISA;
883		1068
884	our @REGISTRY;	1069	our @REGISTRY;
885		1070
886	our $WIN32;	1071	our $WIN32;
887		1072
		1073	our $VERBOSE;
		1074
888	BEGIN {	1075	BEGIN {
889	my $win32 = ! ! ($^O =~ /mswin32/i);	1076	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
890	eval "sub WIN32(){ $win32 }";	1077	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
891	}
892		1078
		1079	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1080	if ${^TAINT};
		1081
893	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1082	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1083
		1084	}
		1085
		1086	our $MAX_SIGNAL_LATENCY = 10;
894		1087
895	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1088	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
896		1089
897	{	1090	{
898	my $idx;	1091	my $idx;
…		…
906	[Event:: => AnyEvent::Impl::Event::],	1099	[Event:: => AnyEvent::Impl::Event::],
907	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1100	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
908	# everything below here will not be autoprobed	1101	# everything below here will not be autoprobed
909	# as the pureperl backend should work everywhere	1102	# as the pureperl backend should work everywhere
910	# and is usually faster	1103	# and is usually faster
911	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
912	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1104	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
913	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1105	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1106	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
914	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1107	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
915	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1108	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
916	[Wx:: => AnyEvent::Impl::POE::],	1109	[Wx:: => AnyEvent::Impl::POE::],
917	[Prima:: => AnyEvent::Impl::POE::],	1110	[Prima:: => AnyEvent::Impl::POE::],
		1111	# IO::Async is just too broken - we would need workarounds for its
		1112	# byzantine signal and broken child handling, among others.
		1113	# IO::Async is rather hard to detect, as it doesn't have any
		1114	# obvious default class.
		1115	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1116	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1117	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
918	);	1118	);
919		1119
920	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1120	our %method = map +($_ => 1),
		1121	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
921		1122
922	our @post_detect;	1123	our @post_detect;
923		1124
924	sub post_detect(&) {	1125	sub post_detect(&) {
925	my ($cb) = @_;	1126	my ($cb) = @_;
…		…
930	1	1131	1
931	} else {	1132	} else {
932	push @post_detect, $cb;	1133	push @post_detect, $cb;
933		1134
934	defined wantarray	1135	defined wantarray
935	? bless \$cb, "AnyEvent::Util::PostDetect"	1136	? bless \$cb, "AnyEvent::Util::postdetect"
936	: ()	1137	: ()
937	}	1138	}
938	}	1139	}
939		1140
940	sub AnyEvent::Util::PostDetect::DESTROY {	1141	sub AnyEvent::Util::postdetect::DESTROY {
941	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1142	@post_detect = grep $_ != ${$_[0]}, @post_detect;
942	}	1143	}
943		1144
944	sub detect() {	1145	sub detect() {
945	unless ($MODEL) {	1146	unless ($MODEL) {
946	no strict 'refs';
947	local $SIG{__DIE__};	1147	local $SIG{__DIE__};
948		1148
949	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1149	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
950	my $model = "AnyEvent::Impl::$1";	1150	my $model = "AnyEvent::Impl::$1";
951	if (eval "require $model") {	1151	if (eval "require $model") {
952	$MODEL = $model;	1152	$MODEL = $model;
953	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1153	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
954	} else {	1154	} else {
955	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1155	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
956	}	1156	}
957	}	1157	}
958		1158
959	# check for already loaded models	1159	# check for already loaded models
960	unless ($MODEL) {	1160	unless ($MODEL) {
961	for (@REGISTRY, @models) {	1161	for (@REGISTRY, @models) {
962	my ($package, $model) = @$_;	1162	my ($package, $model) = @$_;
963	if (${"$package\::VERSION"} > 0) {	1163	if (${"$package\::VERSION"} > 0) {
964	if (eval "require $model") {	1164	if (eval "require $model") {
965	$MODEL = $model;	1165	$MODEL = $model;
966	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1166	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
967	last;	1167	last;
968	}	1168	}
969	}	1169	}
970	}	1170	}
971		1171
…		…
976	my ($package, $model) = @$_;	1176	my ($package, $model) = @$_;
977	if (eval "require $package"	1177	if (eval "require $package"
978	and ${"$package\::VERSION"} > 0	1178	and ${"$package\::VERSION"} > 0
979	and eval "require $model") {	1179	and eval "require $model") {
980	$MODEL = $model;	1180	$MODEL = $model;
981	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1181	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
982	last;	1182	last;
983	}	1183	}
984	}	1184	}
985		1185
986	$MODEL	1186	$MODEL
987	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1187	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
988	}	1188	}
989	}	1189	}
990		1190
991	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1191	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
992		1192
…		…
1002		1202
1003	sub AUTOLOAD {	1203	sub AUTOLOAD {
1004	(my $func = $AUTOLOAD) =~ s/.*://;	1204	(my $func = $AUTOLOAD) =~ s/.*://;
1005		1205
1006	$method{$func}	1206	$method{$func}
1007	or croak "$func: not a valid method for AnyEvent objects";	1207	or Carp::croak "$func: not a valid method for AnyEvent objects";
1008		1208
1009	detect unless $MODEL;	1209	detect unless $MODEL;
1010		1210
1011	my $class = shift;	1211	my $class = shift;
1012	$class->$func (@_);	1212	$class->$func (@_);
1013	}	1213	}
1014		1214
1015	# utility function to dup a filehandle. this is used by many backends	1215	# utility function to dup a filehandle. this is used by many backends
1016	# to support binding more than one watcher per filehandle (they usually	1216	# to support binding more than one watcher per filehandle (they usually
1017	# allow only one watcher per fd, so we dup it to get a different one).	1217	# allow only one watcher per fd, so we dup it to get a different one).
1018	sub _dupfh($$$$) {	1218	sub _dupfh($$;$$) {
1019	my ($poll, $fh, $r, $w) = @_;	1219	my ($poll, $fh, $r, $w) = @_;
1020		1220
1021	# cygwin requires the fh mode to be matching, unix doesn't	1221	# cygwin requires the fh mode to be matching, unix doesn't
1022	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1222	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1023	: $poll eq "w" ? ($w, ">")
1024	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1025		1223
1026	open my $fh2, "$mode&" . fileno $fh	1224	open my $fh2, $mode, $fh
1027	or die "cannot dup() filehandle: $!";	1225	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1028		1226
1029	# we assume CLOEXEC is already set by perl in all important cases	1227	# we assume CLOEXEC is already set by perl in all important cases
1030		1228
1031	($fh2, $rw)	1229	($fh2, $rw)
1032	}	1230	}
1033		1231
1034	package AnyEvent::Base;	1232	package AnyEvent::Base;
1035		1233
1036	# default implementation for now and time	1234	# default implementations for many methods
1037		1235
1038	BEGIN {	1236	sub _time {
		1237	# probe for availability of Time::HiRes
1039	if (eval "use Time::HiRes (); time (); 1") {	1238	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1239	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
1040	*_time = \&Time::HiRes::time;	1240	*_time = \&Time::HiRes::time;
1041	# if (eval "use POSIX (); (POSIX::times())...	1241	# if (eval "use POSIX (); (POSIX::times())...
1042	} else {	1242	} else {
		1243	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1043	*_time = sub { time }; # epic fail	1244	*_time = sub { time }; # epic fail
1044	}	1245	}
		1246
		1247	&_time
1045	}	1248	}
1046		1249
1047	sub time { _time }	1250	sub time { _time }
1048	sub now { _time }	1251	sub now { _time }
		1252	sub now_update { }
1049		1253
1050	# default implementation for ->condvar	1254	# default implementation for ->condvar
1051		1255
1052	sub condvar {	1256	sub condvar {
1053	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1257	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1054	}	1258	}
1055		1259
1056	# default implementation for ->signal	1260	# default implementation for ->signal
1057		1261
		1262	our $HAVE_ASYNC_INTERRUPT;
1058	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);	1263	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1264	our (%SIG_ASY, %SIG_ASY_W);
		1265	our ($SIG_COUNT, $SIG_TW);
1059		1266
1060	sub _signal_exec {	1267	sub _signal_exec {
		1268	$HAVE_ASYNC_INTERRUPT
		1269	? $SIGPIPE_R->drain
1061	sysread $SIGPIPE_R, my $dummy, 4;	1270	: sysread $SIGPIPE_R, my $dummy, 9;
1062		1271
1063	while (%SIG_EV) {	1272	while (%SIG_EV) {
1064	for (keys %SIG_EV) {	1273	for (keys %SIG_EV) {
1065	delete $SIG_EV{$_};	1274	delete $SIG_EV{$_};
1066	$_->() for values %{ $SIG_CB{$_} || {} };	1275	$_->() for values %{ $SIG_CB{$_} || {} };
1067	}	1276	}
1068	}	1277	}
1069	}	1278	}
1070		1279
		1280	# install a dumym wakeupw atcher to reduce signal catching latency
		1281	sub _sig_add() {
		1282	unless ($SIG_COUNT++) {
		1283	# try to align timer on a full-second boundary, if possible
		1284	my $NOW = AnyEvent->now;
		1285
		1286	$SIG_TW = AnyEvent->timer (
		1287	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1288	interval => $MAX_SIGNAL_LATENCY,
		1289	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1290	);
		1291	}
		1292	}
		1293
		1294	sub _sig_del {
		1295	undef $SIG_TW
		1296	unless --$SIG_COUNT;
		1297	}
		1298
		1299	sub _signal {
		1300	my (undef, %arg) = @_;
		1301
		1302	my $signal = uc $arg{signal}
		1303	or Carp::croak "required option 'signal' is missing";
		1304
		1305	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1306
		1307	if ($HAVE_ASYNC_INTERRUPT) {
		1308	# async::interrupt
		1309
		1310	$SIG_ASY{$signal} ||= do {
		1311	my $asy = new Async::Interrupt
		1312	cb => sub { undef $SIG_EV{$signal} },
		1313	signal => $signal,
		1314	pipe => [$SIGPIPE_R->filenos],
		1315	;
		1316	$asy->pipe_autodrain (0);
		1317
		1318	$asy
		1319	};
		1320
		1321	} else {
		1322	# pure perl
		1323
		1324	$SIG{$signal} ||= sub {
		1325	local $!;
		1326	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1327	undef $SIG_EV{$signal};
		1328	};
		1329
		1330	# can't do signal processing without introducing races in pure perl,
		1331	# so limit the signal latency.
		1332	_sig_add;
		1333	}
		1334
		1335	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1336	}
		1337
1071	sub signal {	1338	sub signal {
1072	my (undef, %arg) = @_;	1339	# probe for availability of Async::Interrupt
		1340	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1341	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
1073		1342
1074	unless ($SIGPIPE_R) {	1343	$HAVE_ASYNC_INTERRUPT = 1;
		1344	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1345	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1346
		1347	} else {
		1348	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1349
1075	require Fcntl;	1350	require Fcntl;
1076		1351
1077	if (AnyEvent::WIN32) {	1352	if (AnyEvent::WIN32) {
1078	require AnyEvent::Util;	1353	require AnyEvent::Util;
1079		1354
…		…
1082	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case	1357	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
1083	} else {	1358	} else {
1084	pipe $SIGPIPE_R, $SIGPIPE_W;	1359	pipe $SIGPIPE_R, $SIGPIPE_W;
1085	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;	1360	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
1086	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case	1361	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1362
		1363	# not strictly required, as $^F is normally 2, but let's make sure...
		1364	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1365	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1087	}	1366	}
1088		1367
1089	$SIGPIPE_R	1368	$SIGPIPE_R
1090	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";	1369	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
1091		1370
1092	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1093	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
1094
1095	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);	1371	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
1096	}	1372	}
1097		1373
1098	my $signal = uc $arg{signal}	1374	*signal = \&_signal;
1099	or Carp::croak "required option 'signal' is missing";	1375	&signal
1100
1101	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1102	$SIG{$signal} ||= sub {
1103	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
1104	undef $SIG_EV{$signal};
1105	};
1106
1107	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
1108	}	1376	}
1109		1377
1110	sub AnyEvent::Base::Signal::DESTROY {	1378	sub AnyEvent::Base::signal::DESTROY {
1111	my ($signal, $cb) = @{$_[0]};	1379	my ($signal, $cb) = @{$_[0]};
1112		1380
		1381	_sig_del;
		1382
1113	delete $SIG_CB{$signal}{$cb};	1383	delete $SIG_CB{$signal}{$cb};
1114		1384
		1385	$HAVE_ASYNC_INTERRUPT
		1386	? delete $SIG_ASY{$signal}
		1387	: # delete doesn't work with older perls - they then
		1388	# print weird messages, or just unconditionally exit
		1389	# instead of getting the default action.
		1390	undef $SIG{$signal}
1115	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1391	unless keys %{ $SIG_CB{$signal} };
1116	}	1392	}
1117		1393
1118	# default implementation for ->child	1394	# default implementation for ->child
1119		1395
1120	our %PID_CB;	1396	our %PID_CB;
1121	our $CHLD_W;	1397	our $CHLD_W;
1122	our $CHLD_DELAY_W;	1398	our $CHLD_DELAY_W;
1123	our $PID_IDLE;
1124	our $WNOHANG;	1399	our $WNOHANG;
1125		1400
1126	sub _child_wait {	1401	sub _sigchld {
1127	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1402	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1403	$_->($pid, $?)
1128	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1404	for values %{ $PID_CB{$pid} || {} },
1129	(values %{ $PID_CB{0} || {} });	1405	values %{ $PID_CB{0} || {} };
1130	}	1406	}
1131
1132	undef $PID_IDLE;
1133	}
1134
1135	sub _sigchld {
1136	# make sure we deliver these changes "synchronous" with the event loop.
1137	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1138	undef $CHLD_DELAY_W;
1139	&_child_wait;
1140	});
1141	}	1407	}
1142		1408
1143	sub child {	1409	sub child {
1144	my (undef, %arg) = @_;	1410	my (undef, %arg) = @_;
1145		1411
1146	defined (my $pid = $arg{pid} + 0)	1412	defined (my $pid = $arg{pid} + 0)
1147	or Carp::croak "required option 'pid' is missing";	1413	or Carp::croak "required option 'pid' is missing";
1148		1414
1149	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1415	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1150		1416
1151	unless ($WNOHANG) {	1417	# WNOHANG is almost cetrainly 1 everywhere
		1418	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1419	? 1
1152	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1420	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1153	}
1154		1421
1155	unless ($CHLD_W) {	1422	unless ($CHLD_W) {
1156	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1423	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1157	# child could be a zombie already, so make at least one round	1424	# child could be a zombie already, so make at least one round
1158	&_sigchld;	1425	&_sigchld;
1159	}	1426	}
1160		1427
1161	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1428	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1162	}	1429	}
1163		1430
1164	sub AnyEvent::Base::Child::DESTROY {	1431	sub AnyEvent::Base::child::DESTROY {
1165	my ($pid, $cb) = @{$_[0]};	1432	my ($pid, $cb) = @{$_[0]};
1166		1433
1167	delete $PID_CB{$pid}{$cb};	1434	delete $PID_CB{$pid}{$cb};
1168	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1435	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1169		1436
1170	undef $CHLD_W unless keys %PID_CB;	1437	undef $CHLD_W unless keys %PID_CB;
1171	}	1438	}
1172		1439
		1440	# idle emulation is done by simply using a timer, regardless
		1441	# of whether the process is idle or not, and not letting
		1442	# the callback use more than 50% of the time.
		1443	sub idle {
		1444	my (undef, %arg) = @_;
		1445
		1446	my ($cb, $w, $rcb) = $arg{cb};
		1447
		1448	$rcb = sub {
		1449	if ($cb) {
		1450	$w = _time;
		1451	&$cb;
		1452	$w = _time - $w;
		1453
		1454	# never use more then 50% of the time for the idle watcher,
		1455	# within some limits
		1456	$w = 0.0001 if $w < 0.0001;
		1457	$w = 5 if $w > 5;
		1458
		1459	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1460	} else {
		1461	# clean up...
		1462	undef $w;
		1463	undef $rcb;
		1464	}
		1465	};
		1466
		1467	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1468
		1469	bless \\$cb, "AnyEvent::Base::idle"
		1470	}
		1471
		1472	sub AnyEvent::Base::idle::DESTROY {
		1473	undef $${$_[0]};
		1474	}
		1475
1173	package AnyEvent::CondVar;	1476	package AnyEvent::CondVar;
1174		1477
1175	our @ISA = AnyEvent::CondVar::Base::;	1478	our @ISA = AnyEvent::CondVar::Base::;
1176		1479
1177	package AnyEvent::CondVar::Base;	1480	package AnyEvent::CondVar::Base;
1178		1481
1179	use overload	1482	#use overload
1180	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1483	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1181	fallback => 1;	1484	# fallback => 1;
		1485
		1486	# save 300+ kilobytes by dirtily hardcoding overloading
		1487	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1488	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1489	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1490	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1491
		1492	our $WAITING;
1182		1493
1183	sub _send {	1494	sub _send {
1184	# nop	1495	# nop
1185	}	1496	}
1186		1497
…		…
1199	sub ready {	1510	sub ready {
1200	$_[0]{_ae_sent}	1511	$_[0]{_ae_sent}
1201	}	1512	}
1202		1513
1203	sub _wait {	1514	sub _wait {
		1515	$WAITING
		1516	and !$_[0]{_ae_sent}
		1517	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1518
		1519	local $WAITING = 1;
1204	AnyEvent->one_event while !$_[0]{_ae_sent};	1520	AnyEvent->one_event while !$_[0]{_ae_sent};
1205	}	1521	}
1206		1522
1207	sub recv {	1523	sub recv {
1208	$_[0]->_wait;	1524	$_[0]->_wait;
…		…
1249	so on.	1565	so on.
1250		1566
1251	=head1 ENVIRONMENT VARIABLES	1567	=head1 ENVIRONMENT VARIABLES
1252		1568
1253	The following environment variables are used by this module or its	1569	The following environment variables are used by this module or its
1254	submodules:	1570	submodules.
		1571
		1572	Note that AnyEvent will remove I<all> environment variables starting with
		1573	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1574	enabled.
1255		1575
1256	=over 4	1576	=over 4
1257		1577
1258	=item C<PERL_ANYEVENT_VERBOSE>	1578	=item C<PERL_ANYEVENT_VERBOSE>
1259		1579
…		…
1266	C<PERL_ANYEVENT_MODEL>.	1586	C<PERL_ANYEVENT_MODEL>.
1267		1587
1268	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1588	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1269	model it chooses.	1589	model it chooses.
1270		1590
		1591	When set to C<8> or higher, then AnyEvent will report extra information on
		1592	which optional modules it loads and how it implements certain features.
		1593
1271	=item C<PERL_ANYEVENT_STRICT>	1594	=item C<PERL_ANYEVENT_STRICT>
1272		1595
1273	AnyEvent does not do much argument checking by default, as thorough	1596	AnyEvent does not do much argument checking by default, as thorough
1274	argument checking is very costly. Setting this variable to a true value	1597	argument checking is very costly. Setting this variable to a true value
1275	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1598	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1276	check the arguments passed to most method calls. If it finds any problems	1599	check the arguments passed to most method calls. If it finds any problems,
1277	it will croak.	1600	it will croak.
1278		1601
1279	In other words, enables "strict" mode.	1602	In other words, enables "strict" mode.
1280		1603
1281	Unlike C<use strict>, it is definitely recommended ot keep it off in	1604	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
1282	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1605	>>, it is definitely recommended to keep it off in production. Keeping
1283	developing programs can be very useful, however.	1606	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1607	can be very useful, however.
1284		1608
1285	=item C<PERL_ANYEVENT_MODEL>	1609	=item C<PERL_ANYEVENT_MODEL>
1286		1610
1287	This can be used to specify the event model to be used by AnyEvent, before	1611	This can be used to specify the event model to be used by AnyEvent, before
1288	auto detection and -probing kicks in. It must be a string consisting	1612	auto detection and -probing kicks in. It must be a string consisting
…		…
1331		1655
1332	=item C<PERL_ANYEVENT_MAX_FORKS>	1656	=item C<PERL_ANYEVENT_MAX_FORKS>
1333		1657
1334	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1658	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1335	will create in parallel.	1659	will create in parallel.
		1660
		1661	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1662
		1663	The default value for the C<max_outstanding> parameter for the default DNS
		1664	resolver - this is the maximum number of parallel DNS requests that are
		1665	sent to the DNS server.
		1666
		1667	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1668
		1669	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1670	configuration) in the default resolver. When set to the empty string, no
		1671	default config will be used.
		1672
		1673	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1674
		1675	When neither C<ca_file> nor C<ca_path> was specified during
		1676	L<AnyEvent::TLS> context creation, and either of these environment
		1677	variables exist, they will be used to specify CA certificate locations
		1678	instead of a system-dependent default.
		1679
		1680	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1681
		1682	When these are set to C<1>, then the respective modules are not
		1683	loaded. Mostly good for testing AnyEvent itself.
1336		1684
1337	=back	1685	=back
1338		1686
1339	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1687	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1340		1688
…		…
1585	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	1933	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1586	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	1934	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1587	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	1935	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1588	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	1936	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1589	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	1937	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1938	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1939	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1590	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	1940	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1591	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	1941	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1592	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	1942	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1593	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	1943	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1594		1944
…		…
1623	performance becomes really bad with lots of file descriptors (and few of	1973	performance becomes really bad with lots of file descriptors (and few of
1624	them active), of course, but this was not subject of this benchmark.	1974	them active), of course, but this was not subject of this benchmark.
1625		1975
1626	The C<Event> module has a relatively high setup and callback invocation	1976	The C<Event> module has a relatively high setup and callback invocation
1627	cost, but overall scores in on the third place.	1977	cost, but overall scores in on the third place.
		1978
		1979	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1980	when using its pure perl backend.
1628		1981
1629	C<Glib>'s memory usage is quite a bit higher, but it features a	1982	C<Glib>'s memory usage is quite a bit higher, but it features a
1630	faster callback invocation and overall ends up in the same class as	1983	faster callback invocation and overall ends up in the same class as
1631	C<Event>. However, Glib scales extremely badly, doubling the number of	1984	C<Event>. However, Glib scales extremely badly, doubling the number of
1632	watchers increases the processing time by more than a factor of four,	1985	watchers increases the processing time by more than a factor of four,
…		…
1710	it to another server. This includes deleting the old timeout and creating	2063	it to another server. This includes deleting the old timeout and creating
1711	a new one that moves the timeout into the future.	2064	a new one that moves the timeout into the future.
1712		2065
1713	=head3 Results	2066	=head3 Results
1714		2067
1715	name sockets create request	2068	name sockets create request
1716	EV 20000 69.01 11.16	2069	EV 20000 69.01 11.16
1717	Perl 20000 73.32 35.87	2070	Perl 20000 73.32 35.87
		2071	IOAsync 20000 157.00 98.14 epoll
		2072	IOAsync 20000 159.31 616.06 poll
1718	Event 20000 212.62 257.32	2073	Event 20000 212.62 257.32
1719	Glib 20000 651.16 1896.30	2074	Glib 20000 651.16 1896.30
1720	POE 20000 349.67 12317.24 uses POE::Loop::Event	2075	POE 20000 349.67 12317.24 uses POE::Loop::Event
1721		2076
1722	=head3 Discussion	2077	=head3 Discussion
1723		2078
1724	This benchmark I<does> measure scalability and overall performance of the	2079	This benchmark I<does> measure scalability and overall performance of the
1725	particular event loop.	2080	particular event loop.
…		…
1727	EV is again fastest. Since it is using epoll on my system, the setup time	2082	EV is again fastest. Since it is using epoll on my system, the setup time
1728	is relatively high, though.	2083	is relatively high, though.
1729		2084
1730	Perl surprisingly comes second. It is much faster than the C-based event	2085	Perl surprisingly comes second. It is much faster than the C-based event
1731	loops Event and Glib.	2086	loops Event and Glib.
		2087
		2088	IO::Async performs very well when using its epoll backend, and still quite
		2089	good compared to Glib when using its pure perl backend.
1732		2090
1733	Event suffers from high setup time as well (look at its code and you will	2091	Event suffers from high setup time as well (look at its code and you will
1734	understand why). Callback invocation also has a high overhead compared to	2092	understand why). Callback invocation also has a high overhead compared to
1735	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2093	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1736	uses select or poll in basically all documented configurations.	2094	uses select or poll in basically all documented configurations.
…		…
1799	=item * C-based event loops perform very well with small number of	2157	=item * C-based event loops perform very well with small number of
1800	watchers, as the management overhead dominates.	2158	watchers, as the management overhead dominates.
1801		2159
1802	=back	2160	=back
1803		2161
		2162	=head2 THE IO::Lambda BENCHMARK
		2163
		2164	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2165	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2166	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2167	shouldn't come as a surprise to anybody). As such, the benchmark is
		2168	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2169	very optimal. But how would AnyEvent compare when used without the extra
		2170	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2171
		2172	The benchmark itself creates an echo-server, and then, for 500 times,
		2173	connects to the echo server, sends a line, waits for the reply, and then
		2174	creates the next connection. This is a rather bad benchmark, as it doesn't
		2175	test the efficiency of the framework or much non-blocking I/O, but it is a
		2176	benchmark nevertheless.
		2177
		2178	name runtime
		2179	Lambda/select 0.330 sec
		2180	+ optimized 0.122 sec
		2181	Lambda/AnyEvent 0.327 sec
		2182	+ optimized 0.138 sec
		2183	Raw sockets/select 0.077 sec
		2184	POE/select, components 0.662 sec
		2185	POE/select, raw sockets 0.226 sec
		2186	POE/select, optimized 0.404 sec
		2187
		2188	AnyEvent/select/nb 0.085 sec
		2189	AnyEvent/EV/nb 0.068 sec
		2190	+state machine 0.134 sec
		2191
		2192	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2193	benchmarks actually make blocking connects and use 100% blocking I/O,
		2194	defeating the purpose of an event-based solution. All of the newly
		2195	written AnyEvent benchmarks use 100% non-blocking connects (using
		2196	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2197	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2198	generally require a lot more bookkeeping and event handling than blocking
		2199	connects (which involve a single syscall only).
		2200
		2201	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2202	offers similar expressive power as POE and IO::Lambda, using conventional
		2203	Perl syntax. This means that both the echo server and the client are 100%
		2204	non-blocking, further placing it at a disadvantage.
		2205
		2206	As you can see, the AnyEvent + EV combination even beats the
		2207	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2208	backend easily beats IO::Lambda and POE.
		2209
		2210	And even the 100% non-blocking version written using the high-level (and
		2211	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2212	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2213	in a non-blocking way.
		2214
		2215	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2216	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2217	part of the IO::lambda distribution and were used without any changes.
		2218
1804		2219
1805	=head1 SIGNALS	2220	=head1 SIGNALS
1806		2221
1807	AnyEvent currently installs handlers for these signals:	2222	AnyEvent currently installs handlers for these signals:
1808		2223
…		…
1811	=item SIGCHLD	2226	=item SIGCHLD
1812		2227
1813	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2228	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1814	emulation for event loops that do not support them natively. Also, some	2229	emulation for event loops that do not support them natively. Also, some
1815	event loops install a similar handler.	2230	event loops install a similar handler.
		2231
		2232	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2233	AnyEvent will reset it to default, to avoid losing child exit statuses.
1816		2234
1817	=item SIGPIPE	2235	=item SIGPIPE
1818		2236
1819	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2237	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1820	when AnyEvent gets loaded.	2238	when AnyEvent gets loaded.
…		…
1832		2250
1833	=back	2251	=back
1834		2252
1835	=cut	2253	=cut
1836		2254
		2255	undef $SIG{CHLD}
		2256	if $SIG{CHLD} eq 'IGNORE';
		2257
1837	$SIG{PIPE} = sub { }	2258	$SIG{PIPE} = sub { }
1838	unless defined $SIG{PIPE};	2259	unless defined $SIG{PIPE};
		2260
		2261	=head1 RECOMMENDED/OPTIONAL MODULES
		2262
		2263	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2264	it's built-in modules) are required to use it.
		2265
		2266	That does not mean that AnyEvent won't take advantage of some additional
		2267	modules if they are installed.
		2268
		2269	This section epxlains which additional modules will be used, and how they
		2270	affect AnyEvent's operetion.
		2271
		2272	=over 4
		2273
		2274	=item L<Async::Interrupt>
		2275
		2276	This slightly arcane module is used to implement fast signal handling: To
		2277	my knowledge, there is no way to do completely race-free and quick
		2278	signal handling in pure perl. To ensure that signals still get
		2279	delivered, AnyEvent will start an interval timer to wake up perl (and
		2280	catch the signals) with some delay (default is 10 seconds, look for
		2281	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2282
		2283	If this module is available, then it will be used to implement signal
		2284	catching, which means that signals will not be delayed, and the event loop
		2285	will not be interrupted regularly, which is more efficient (And good for
		2286	battery life on laptops).
		2287
		2288	This affects not just the pure-perl event loop, but also other event loops
		2289	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2290
		2291	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2292	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2293	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2294	does nothing for those backends.
		2295
		2296	=item L<EV>
		2297
		2298	This module isn't really "optional", as it is simply one of the backend
		2299	event loops that AnyEvent can use. However, it is simply the best event
		2300	loop available in terms of features, speed and stability: It supports
		2301	the AnyEvent API optimally, implements all the watcher types in XS, does
		2302	automatic timer adjustments even when no monotonic clock is available,
		2303	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2304	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2305	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2306
		2307	=item L<Guard>
		2308
		2309	The guard module, when used, will be used to implement
		2310	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2311	lot less memory), but otherwise doesn't affect guard operation much. It is
		2312	purely used for performance.
		2313
		2314	=item L<JSON> and L<JSON::XS>
		2315
		2316	This module is required when you want to read or write JSON data via
		2317	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2318	advantage of the ulta-high-speed L<JSON::XS> module when it is installed.
		2319
		2320	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2321	installed.
		2322
		2323	=item L<Net::SSLeay>
		2324
		2325	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2326	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2327	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2328
		2329	=item L<Time::HiRes>
		2330
		2331	This module is part of perl since release 5.008. It will be used when the
		2332	chosen event library does not come with a timing source on it's own. The
		2333	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2334	try to use a monotonic clock for timing stability.
		2335
		2336	=back
1839		2337
1840		2338
1841	=head1 FORK	2339	=head1 FORK
1842		2340
1843	Most event libraries are not fork-safe. The ones who are usually are	2341	Most event libraries are not fork-safe. The ones who are usually are
1844	because they rely on inefficient but fork-safe C<select> or C<poll>	2342	because they rely on inefficient but fork-safe C<select> or C<poll>
1845	calls. Only L<EV> is fully fork-aware.	2343	calls. Only L<EV> is fully fork-aware.
1846		2344
1847	If you have to fork, you must either do so I<before> creating your first	2345	If you have to fork, you must either do so I<before> creating your first
1848	watcher OR you must not use AnyEvent at all in the child.	2346	watcher OR you must not use AnyEvent at all in the child OR you must do
		2347	something completely out of the scope of AnyEvent.
1849		2348
1850		2349
1851	=head1 SECURITY CONSIDERATIONS	2350	=head1 SECURITY CONSIDERATIONS
1852		2351
1853	AnyEvent can be forced to load any event model via	2352	AnyEvent can be forced to load any event model via
…		…
1865	use AnyEvent;	2364	use AnyEvent;
1866		2365
1867	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2366	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1868	be used to probe what backend is used and gain other information (which is	2367	be used to probe what backend is used and gain other information (which is
1869	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2368	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1870	$ENV{PERL_ANYEGENT_STRICT}.	2369	$ENV{PERL_ANYEVENT_STRICT}.
		2370
		2371	Note that AnyEvent will remove I<all> environment variables starting with
		2372	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2373	enabled.
1871		2374
1872		2375
1873	=head1 BUGS	2376	=head1 BUGS
1874		2377
1875	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2378	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
…		…
1887	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2390	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1888		2391
1889	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2392	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1890	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2393	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1891	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2394	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1892	L<AnyEvent::Impl::POE>.	2395	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1893		2396
1894	Non-blocking file handles, sockets, TCP clients and	2397	Non-blocking file handles, sockets, TCP clients and
1895	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2398	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1896		2399
1897	Asynchronous DNS: L<AnyEvent::DNS>.	2400	Asynchronous DNS: L<AnyEvent::DNS>.
1898		2401
1899	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2402	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2403	L<Coro::Event>,
1900		2404
1901	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2405	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2406	L<AnyEvent::HTTP>.
1902		2407
1903		2408
1904	=head1 AUTHOR	2409	=head1 AUTHOR
1905		2410
1906	Marc Lehmann <schmorp@schmorp.de>	2411	Marc Lehmann <schmorp@schmorp.de>

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