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Revision 1.190 by root, Wed Nov 5 02:21:27 2008 UTC vs.
Revision 1.245 by root, Sat Jul 18 05:19:09 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 $condvar gets ->send
29	# use a condvar in callback mode:	37	# use a condvar in callback mode:
…		…
137	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
138	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
139	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
140	is in control).	148	is in control).
141		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
142	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
143	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
144	to it).	158	to it).
145		159
146	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
162	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
163		177
164	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
165	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
166		180
167	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
168	(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
169	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
170	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
171	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.
172		192
173	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
174	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
175	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
176		196
…		…
308	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
309	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
310	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
311	account.	331	account.
312		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
313	=back	348	=back
314		349
315	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
316		351
317	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
…		…
326	invocation, and callback invocation will be synchronous. Synchronous means	361	invocation, and callback invocation will be synchronous. Synchronous means
327	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,
328	but it is guaranteed not to interrupt any other callbacks.	363	but it is guaranteed not to interrupt any other callbacks.
329		364
330	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
331	between multiple watchers.	366	between multiple watchers, and AnyEvent will ensure that signals will not
		367	interrupt your program at bad times.
332		368
333	This watcher might use C<%SIG>, so programs overwriting those signals	369	This watcher might use C<%SIG> (depending on the event loop used),
334	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.
335		383
336	Example: exit on SIGINT	384	Example: exit on SIGINT
337		385
338	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	386	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
339		387
…		…
357		405
358	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
359	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
360	have exited already (and no SIGCHLD will be sent anymore).	408	have exited already (and no SIGCHLD will be sent anymore).
361		409
362	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
363	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
364	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.
365		416
366	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
367	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
368	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.
369		425
370	Example: fork a process and wait for it	426	Example: fork a process and wait for it
371		427
372	my $done = AnyEvent->condvar;	428	my $done = AnyEvent->condvar;
373		429
…		…
383	);	439	);
384		440
385	# do something else, then wait for process exit	441	# do something else, then wait for process exit
386	$done->recv;	442	$done->recv;
387		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
388	=head2 CONDITION VARIABLES	479	=head2 CONDITION VARIABLES
389		480
390	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
391	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
392	will actively watch for new events and call your callbacks.	483	will actively watch for new events and call your callbacks.
393		484
394	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
395	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).
396		487
397	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
398	because they represent a condition that must become true.	489	because they represent a condition that must become true.
399		490
		491	Now is probably a good time to look at the examples further below.
		492
400	Condition variables can be created by calling the C<< AnyEvent->condvar	493	Condition variables can be created by calling the C<< AnyEvent->condvar
401	>> method, usually without arguments. The only argument pair allowed is	494	>> method, usually without arguments. The only argument pair allowed is
402
403	C<cb>, which specifies a callback to be called when the condition variable	495	C<cb>, which specifies a callback to be called when the condition variable
404	becomes true, with the condition variable as the first argument (but not	496	becomes true, with the condition variable as the first argument (but not
405	the results).	497	the results).
406		498
407	After creation, the condition variable is "false" until it becomes "true"	499	After creation, the condition variable is "false" until it becomes "true"
…		…
456	after => 1,	548	after => 1,
457	cb => sub { $result_ready->send },	549	cb => sub { $result_ready->send },
458	);	550	);
459		551
460	# this "blocks" (while handling events) till the callback	552	# this "blocks" (while handling events) till the callback
461	# calls send	553	# calls -<send
462	$result_ready->recv;	554	$result_ready->recv;
463		555
464	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
465	condition variables are also code references.	557	variables are also callable directly.
466		558
467	my $done = AnyEvent->condvar;	559	my $done = AnyEvent->condvar;
468	my $delay = AnyEvent->timer (after => 5, cb => $done);	560	my $delay = AnyEvent->timer (after => 5, cb => $done);
469	$done->recv;	561	$done->recv;
470		562
…		…
476		568
477	...	569	...
478		570
479	my @info = $couchdb->info->recv;	571	my @info = $couchdb->info->recv;
480		572
481	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
482	results are available:	574	results are available:
483		575
484	$couchdb->info->cb (sub {	576	$couchdb->info->cb (sub {
485	my @info = $_[0]->recv;	577	my @info = $_[0]->recv;
486	});	578	});
…		…
504	immediately from within send.	596	immediately from within send.
505		597
506	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
507	future C<< ->recv >> calls.	599	future C<< ->recv >> calls.
508		600
509	Condition variables are overloaded so one can call them directly	601	Condition variables are overloaded so one can call them directly (as if
510	(as a code reference). Calling them directly is the same as calling	602	they were a code reference). Calling them directly is the same as calling
511	C<send>. Note, however, that many C-based event loops do not handle	603	C<send>.
512	overloading, so as tempting as it may be, passing a condition variable
513	instead of a callback does not work. Both the pure perl and EV loops
514	support overloading, however, as well as all functions that use perl to
515	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
516	example).
517		604
518	=item $cv->croak ($error)	605	=item $cv->croak ($error)
519		606
520	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
521	C<Carp::croak> with the given error message/object/scalar.	608	C<Carp::croak> with the given error message/object/scalar.
522		609
523	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
524	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.
525		616
526	=item $cv->begin ([group callback])	617	=item $cv->begin ([group callback])
527		618
528	=item $cv->end	619	=item $cv->end
529
530	These two methods are EXPERIMENTAL and MIGHT CHANGE.
531		620
532	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
533	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
534	to use a condition variable for the whole process.	623	to use a condition variable for the whole process.
535		624
…		…
537	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
538	>>, 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
539	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
540	callback was set, C<send> will be called without any arguments.	629	callback was set, C<send> will be called without any arguments.
541		630
542	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:
543		662
544	my $cv = AnyEvent->condvar;	663	my $cv = AnyEvent->condvar;
545		664
546	my %result;	665	my %result;
547	$cv->begin (sub { $cv->send (\%result) });	666	$cv->begin (sub { $cv->send (\%result) });
…		…
567	loop, which serves two important purposes: first, it sets the callback	686	loop, which serves two important purposes: first, it sets the callback
568	to be called once the counter reaches C<0>, and second, it ensures that	687	to be called once the counter reaches C<0>, and second, it ensures that
569	C<send> is called even when C<no> hosts are being pinged (the loop	688	C<send> is called even when C<no> hosts are being pinged (the loop
570	doesn't execute once).	689	doesn't execute once).
571		690
572	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
573	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
574	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
575	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>.
576		696
577	=back	697	=back
578		698
579	=head3 METHODS FOR CONSUMERS	699	=head3 METHODS FOR CONSUMERS
580		700
…		…
596	function will call C<croak>.	716	function will call C<croak>.
597		717
598	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,
599	in scalar context only the first one will be returned.	719	in scalar context only the first one will be returned.
600		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
601	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
602	(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
603	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
604	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
605	condition variables with some kind of request results and supporting	732	condition variables with some kind of request results and supporting
606	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,
607	while still supporting blocking waits if the caller so desires).	734	while still supporting blocking waits if the caller so desires).
608		735
609	Another reason I<never> to C<< ->recv >> in a module is that you cannot
610	sensibly have two C<< ->recv >>'s in parallel, as that would require
611	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
612	can supply.
613
614	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
615	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
616	versions and also integrates coroutines into AnyEvent, making blocking
617	C<< ->recv >> calls perfectly safe as long as they are done from another
618	coroutine (one that doesn't run the event loop).
619
620	You can ensure that C<< -recv >> never blocks by setting a callback and	736	You can ensure that C<< -recv >> never blocks by setting a callback and
621	only calling C<< ->recv >> from within that callback (or at a later	737	only calling C<< ->recv >> from within that callback (or at a later
622	time). This will work even when the event loop does not support blocking	738	time). This will work even when the event loop does not support blocking
623	waits otherwise.	739	waits otherwise.
624		740
…		…
637	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
638	is guaranteed not to block.	754	is guaranteed not to block.
639		755
640	=back	756	=back
641		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
642	=head1 GLOBAL VARIABLES AND FUNCTIONS	825	=head1 GLOBAL VARIABLES AND FUNCTIONS
643		826
		827	These are not normally required to use AnyEvent, but can be useful to
		828	write AnyEvent extension modules.
		829
644	=over 4	830	=over 4
645		831
646	=item $AnyEvent::MODEL	832	=item $AnyEvent::MODEL
647		833
648	Contains C<undef> until the first watcher is being created. Then it	834	Contains C<undef> until the first watcher is being created, before the
		835	backend has been autodetected.
		836
649	contains the event model that is being used, which is the name of the	837	Afterwards it contains the event model that is being used, which is the
650	Perl class implementing the model. This class is usually one of the	838	name of the Perl class implementing the model. This class is usually one
651	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	839	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
652	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	840	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
653		841	will be C<urxvt::anyevent>).
654	The known classes so far are:
655
656	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
657	AnyEvent::Impl::Event based on Event, second best choice.
658	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
659	AnyEvent::Impl::Glib based on Glib, third-best choice.
660	AnyEvent::Impl::Tk based on Tk, very bad choice.
661	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
662	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
663	AnyEvent::Impl::POE based on POE, not generic enough for full support.
664
665	There is no support for WxWidgets, as WxWidgets has no support for
666	watching file handles. However, you can use WxWidgets through the
667	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
668	second, which was considered to be too horrible to even consider for
669	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
670	it's adaptor.
671
672	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
673	autodetecting them.
674		842
675	=item AnyEvent::detect	843	=item AnyEvent::detect
676		844
677	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	845	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
678	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
679	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
680	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>.
681		852
682	=item $guard = AnyEvent::post_detect { BLOCK }	853	=item $guard = AnyEvent::post_detect { BLOCK }
683		854
684	Arranges for the code block to be executed as soon as the event model is	855	Arranges for the code block to be executed as soon as the event model is
685	autodetected (or immediately if this has already happened).	856	autodetected (or immediately if this has already happened).
		857
		858	The block will be executed I<after> the actual backend has been detected
		859	(C<$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.
686		868
687	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
688	that automatically removes the callback again when it is destroyed. See	870	that automatically removes the callback again when it is destroyed. See
689	L<Coro::BDB> for a case where this is useful.	871	L<Coro::BDB> for a case where this is useful.
690		872
…		…
693	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
694	before or after loading AnyEvent), then they will called directly after	876	before or after loading AnyEvent), then they will called directly after
695	the event loop has been chosen.	877	the event loop has been chosen.
696		878
697	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:
698	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
699	and the array will be ignored.	881	array will be ignored.
700		882
701	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.
702		890
703	=back	891	=back
704		892
705	=head1 WHAT TO DO IN A MODULE	893	=head1 WHAT TO DO IN A MODULE
706		894
…		…
761		949
762		950
763	=head1 OTHER MODULES	951	=head1 OTHER MODULES
764		952
765	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
766	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
767	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
768	available via CPAN.	956	come with AnyEvent, most are available via CPAN.
769		957
770	=over 4	958	=over 4
771		959
772	=item L<AnyEvent::Util>	960	=item L<AnyEvent::Util>
773		961
…		…
782		970
783	=item L<AnyEvent::Handle>	971	=item L<AnyEvent::Handle>
784		972
785	Provide read and write buffers, manages watchers for reads and writes,	973	Provide read and write buffers, manages watchers for reads and writes,
786	supports raw and formatted I/O, I/O queued and fully transparent and	974	supports raw and formatted I/O, I/O queued and fully transparent and
787	non-blocking SSL/TLS.	975	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
788		976
789	=item L<AnyEvent::DNS>	977	=item L<AnyEvent::DNS>
790		978
791	Provides rich asynchronous DNS resolver capabilities.	979	Provides rich asynchronous DNS resolver capabilities.
792		980
…		…
820		1008
821	=item L<AnyEvent::GPSD>	1009	=item L<AnyEvent::GPSD>
822		1010
823	A non-blocking interface to gpsd, a daemon delivering GPS information.	1011	A non-blocking interface to gpsd, a daemon delivering GPS information.
824		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
825	=item L<AnyEvent::IGS>	1022	=item L<AnyEvent::IGS>
826		1023
827	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
828	L<App::IGS>).	1025	L<App::IGS>).
829		1026
830	=item L<AnyEvent::IRC>
831
832	AnyEvent based IRC client module family (replacing the older Net::IRC3).
833
834	=item L<Net::XMPP2>
835
836	AnyEvent based XMPP (Jabber protocol) module family.
837
838	=item L<Net::FCP>	1027	=item L<Net::FCP>
839		1028
840	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1029	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
841	of AnyEvent.	1030	of AnyEvent.
842		1031
…		…
846		1035
847	=item L<Coro>	1036	=item L<Coro>
848		1037
849	Has special support for AnyEvent via L<Coro::AnyEvent>.	1038	Has special support for AnyEvent via L<Coro::AnyEvent>.
850		1039
851	=item L<IO::Lambda>
852
853	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
854
855	=back	1040	=back
856		1041
857	=cut	1042	=cut
858		1043
859	package AnyEvent;	1044	package AnyEvent;
860		1045
		1046	# basically a tuned-down version of common::sense
		1047	sub common_sense {
861	no warnings;	1048	# no warnings
		1049	${^WARNING_BITS} ^= ${^WARNING_BITS};
862	use strict qw(vars subs);	1050	# use strict vars subs
		1051	$^H |= 0x00000600;
		1052	}
863		1053
		1054	BEGIN { AnyEvent::common_sense }
		1055
864	use Carp;	1056	use Carp ();
865		1057
866	our $VERSION = 4.32;	1058	our $VERSION = 4.85;
867	our $MODEL;	1059	our $MODEL;
868		1060
869	our $AUTOLOAD;	1061	our $AUTOLOAD;
870	our @ISA;	1062	our @ISA;
871		1063
872	our @REGISTRY;	1064	our @REGISTRY;
873		1065
874	our $WIN32;	1066	our $WIN32;
875		1067
		1068	our $VERBOSE;
		1069
876	BEGIN {	1070	BEGIN {
877	my $win32 = ! ! ($^O =~ /mswin32/i);	1071	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
878	eval "sub WIN32(){ $win32 }";	1072	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
879	}
880		1073
		1074	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1075	if ${^TAINT};
		1076
881	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1077	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1078
		1079	}
		1080
		1081	our $MAX_SIGNAL_LATENCY = 10;
882		1082
883	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1083	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
884		1084
885	{	1085	{
886	my $idx;	1086	my $idx;
…		…
894	[Event:: => AnyEvent::Impl::Event::],	1094	[Event:: => AnyEvent::Impl::Event::],
895	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1095	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
896	# everything below here will not be autoprobed	1096	# everything below here will not be autoprobed
897	# as the pureperl backend should work everywhere	1097	# as the pureperl backend should work everywhere
898	# and is usually faster	1098	# and is usually faster
899	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
900	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1099	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
901	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1100	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1101	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
902	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1102	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
903	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1103	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
904	[Wx:: => AnyEvent::Impl::POE::],	1104	[Wx:: => AnyEvent::Impl::POE::],
905	[Prima:: => AnyEvent::Impl::POE::],	1105	[Prima:: => AnyEvent::Impl::POE::],
		1106	# IO::Async is just too broken - we would need workarounds for its
		1107	# byzantine signal and broken child handling, among others.
		1108	# IO::Async is rather hard to detect, as it doesn't have any
		1109	# obvious default class.
		1110	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1111	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1112	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
906	);	1113	);
907		1114
908	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1115	our %method = map +($_ => 1),
		1116	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
909		1117
910	our @post_detect;	1118	our @post_detect;
911		1119
912	sub post_detect(&) {	1120	sub post_detect(&) {
913	my ($cb) = @_;	1121	my ($cb) = @_;
…		…
918	1	1126	1
919	} else {	1127	} else {
920	push @post_detect, $cb;	1128	push @post_detect, $cb;
921		1129
922	defined wantarray	1130	defined wantarray
923	? bless \$cb, "AnyEvent::Util::PostDetect"	1131	? bless \$cb, "AnyEvent::Util::postdetect"
924	: ()	1132	: ()
925	}	1133	}
926	}	1134	}
927		1135
928	sub AnyEvent::Util::PostDetect::DESTROY {	1136	sub AnyEvent::Util::postdetect::DESTROY {
929	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1137	@post_detect = grep $_ != ${$_[0]}, @post_detect;
930	}	1138	}
931		1139
932	sub detect() {	1140	sub detect() {
933	unless ($MODEL) {	1141	unless ($MODEL) {
934	no strict 'refs';
935	local $SIG{__DIE__};	1142	local $SIG{__DIE__};
936		1143
937	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1144	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
938	my $model = "AnyEvent::Impl::$1";	1145	my $model = "AnyEvent::Impl::$1";
939	if (eval "require $model") {	1146	if (eval "require $model") {
940	$MODEL = $model;	1147	$MODEL = $model;
941	warn "AnyEvent: loaded model '$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 $VERBOSE >= 2;
942	} else {	1149	} else {
943	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1150	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
944	}	1151	}
945	}	1152	}
946		1153
947	# check for already loaded models	1154	# check for already loaded models
948	unless ($MODEL) {	1155	unless ($MODEL) {
949	for (@REGISTRY, @models) {	1156	for (@REGISTRY, @models) {
950	my ($package, $model) = @$_;	1157	my ($package, $model) = @$_;
951	if (${"$package\::VERSION"} > 0) {	1158	if (${"$package\::VERSION"} > 0) {
952	if (eval "require $model") {	1159	if (eval "require $model") {
953	$MODEL = $model;	1160	$MODEL = $model;
954	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1161	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
955	last;	1162	last;
956	}	1163	}
957	}	1164	}
958	}	1165	}
959		1166
…		…
964	my ($package, $model) = @$_;	1171	my ($package, $model) = @$_;
965	if (eval "require $package"	1172	if (eval "require $package"
966	and ${"$package\::VERSION"} > 0	1173	and ${"$package\::VERSION"} > 0
967	and eval "require $model") {	1174	and eval "require $model") {
968	$MODEL = $model;	1175	$MODEL = $model;
969	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1176	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
970	last;	1177	last;
971	}	1178	}
972	}	1179	}
973		1180
974	$MODEL	1181	$MODEL
975	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1182	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
976	}	1183	}
977	}	1184	}
978		1185
979	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1186	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
980		1187
…		…
990		1197
991	sub AUTOLOAD {	1198	sub AUTOLOAD {
992	(my $func = $AUTOLOAD) =~ s/.*://;	1199	(my $func = $AUTOLOAD) =~ s/.*://;
993		1200
994	$method{$func}	1201	$method{$func}
995	or croak "$func: not a valid method for AnyEvent objects";	1202	or Carp::croak "$func: not a valid method for AnyEvent objects";
996		1203
997	detect unless $MODEL;	1204	detect unless $MODEL;
998		1205
999	my $class = shift;	1206	my $class = shift;
1000	$class->$func (@_);	1207	$class->$func (@_);
1001	}	1208	}
1002		1209
1003	# 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
1004	# to support binding more than one watcher per filehandle (they usually	1211	# to support binding more than one watcher per filehandle (they usually
1005	# allow only one watcher per fd, so we dup it to get a different one).	1212	# allow only one watcher per fd, so we dup it to get a different one).
1006	sub _dupfh($$$$) {	1213	sub _dupfh($$;$$) {
1007	my ($poll, $fh, $r, $w) = @_;	1214	my ($poll, $fh, $r, $w) = @_;
1008		1215
1009	require Fcntl;
1010
1011	# cygwin requires the fh mode to be matching, unix doesn't	1216	# cygwin requires the fh mode to be matching, unix doesn't
1012	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1217	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1013	: $poll eq "w" ? ($w, ">")
1014	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1015		1218
1016	open my $fh2, "$mode&" . fileno $fh	1219	open my $fh2, $mode, $fh
1017	or die "cannot dup() filehandle: $!";	1220	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1018		1221
1019	# 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
1020		1223
1021	($fh2, $rw)	1224	($fh2, $rw)
1022	}	1225	}
1023		1226
1024	package AnyEvent::Base;	1227	package AnyEvent::Base;
1025		1228
1026	# default implementation for now and time	1229	# default implementations for many methods
1027		1230
1028	BEGIN {	1231	sub _time {
		1232	# probe for availability of Time::HiRes
1029	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;
1030	*_time = \&Time::HiRes::time;	1235	*_time = \&Time::HiRes::time;
1031	# if (eval "use POSIX (); (POSIX::times())...	1236	# if (eval "use POSIX (); (POSIX::times())...
1032	} else {	1237	} else {
		1238	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1033	*_time = sub { time }; # epic fail	1239	*_time = sub { time }; # epic fail
1034	}	1240	}
		1241
		1242	&_time
1035	}	1243	}
1036		1244
1037	sub time { _time }	1245	sub time { _time }
1038	sub now { _time }	1246	sub now { _time }
		1247	sub now_update { }
1039		1248
1040	# default implementation for ->condvar	1249	# default implementation for ->condvar
1041		1250
1042	sub condvar {	1251	sub condvar {
1043	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1252	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1044	}	1253	}
1045		1254
1046	# default implementation for ->signal	1255	# default implementation for ->signal
1047		1256
1048	our %SIG_CB;	1257	our $HAVE_ASYNC_INTERRUPT;
		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);
1049		1261
		1262	sub _signal_exec {
		1263	$HAVE_ASYNC_INTERRUPT
		1264	? $SIGPIPE_R->drain
		1265	: sysread $SIGPIPE_R, my $dummy, 9;
		1266
		1267	while (%SIG_EV) {
		1268	for (keys %SIG_EV) {
		1269	delete $SIG_EV{$_};
		1270	$_->() for values %{ $SIG_CB{$_} || {} };
		1271	}
		1272	}
		1273	}
		1274
1050	sub signal {	1275	sub _signal {
1051	my (undef, %arg) = @_;	1276	my (undef, %arg) = @_;
1052		1277
1053	my $signal = uc $arg{signal}	1278	my $signal = uc $arg{signal}
1054	or Carp::croak "required option 'signal' is missing";	1279	or Carp::croak "required option 'signal' is missing";
1055		1280
1056	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1281	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1282
		1283	if ($HAVE_ASYNC_INTERRUPT) {
		1284	# async::interrupt
		1285
		1286	$SIG_ASY{$signal} ||= do {
		1287	my $asy = new Async::Interrupt
		1288	cb => sub { undef $SIG_EV{$signal} },
		1289	signal => $signal,
		1290	pipe => [$SIGPIPE_R->filenos],
		1291	;
		1292	$asy->pipe_autodrain (0);
		1293
		1294	$asy
		1295	};
		1296
		1297	} else {
		1298	# pure perl
		1299
1057	$SIG{$signal} ||= sub {	1300	$SIG{$signal} ||= sub {
1058	$_->() for values %{ $SIG_CB{$signal} || {} };	1301	local $!;
		1302	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1303	undef $SIG_EV{$signal};
		1304	};
		1305
		1306	# can't do signal processing without introducing races in pure perl,
		1307	# so limit the signal latency.
		1308	++$SIG_COUNT;
		1309	$SIG_TW ||= AnyEvent->timer (
		1310	after => $MAX_SIGNAL_LATENCY,
		1311	interval => $MAX_SIGNAL_LATENCY,
		1312	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1313	);
1059	};	1314	}
1060		1315
1061	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1316	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1062	}	1317	}
1063		1318
		1319	sub signal {
		1320	# probe for availability of Async::Interrupt
		1321	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1322	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1323
		1324	$HAVE_ASYNC_INTERRUPT = 1;
		1325	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1326	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1327
		1328	} else {
		1329	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1330
		1331	require Fcntl;
		1332
		1333	if (AnyEvent::WIN32) {
		1334	require AnyEvent::Util;
		1335
		1336	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1337	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1338	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1339	} else {
		1340	pipe $SIGPIPE_R, $SIGPIPE_W;
		1341	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1342	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1343
		1344	# not strictly required, as $^F is normally 2, but let's make sure...
		1345	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1346	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1347	}
		1348
		1349	$SIGPIPE_R
		1350	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1351
		1352	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1353	}
		1354
		1355	*signal = \&_signal;
		1356	&signal
		1357	}
		1358
1064	sub AnyEvent::Base::Signal::DESTROY {	1359	sub AnyEvent::Base::signal::DESTROY {
1065	my ($signal, $cb) = @{$_[0]};	1360	my ($signal, $cb) = @{$_[0]};
1066		1361
		1362	undef $SIG_TW
		1363	unless --$SIG_COUNT;
		1364
1067	delete $SIG_CB{$signal}{$cb};	1365	delete $SIG_CB{$signal}{$cb};
1068		1366
		1367	$HAVE_ASYNC_INTERRUPT
		1368	? delete $SIG_ASY{$signal}
		1369	: # delete doesn't work with older perls - they then
		1370	# print weird messages, or just unconditionally exit
		1371	# instead of getting the default action.
		1372	undef $SIG{$signal}
1069	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1373	unless keys %{ $SIG_CB{$signal} };
1070	}	1374	}
1071		1375
1072	# default implementation for ->child	1376	# default implementation for ->child
1073		1377
1074	our %PID_CB;	1378	our %PID_CB;
1075	our $CHLD_W;	1379	our $CHLD_W;
1076	our $CHLD_DELAY_W;	1380	our $CHLD_DELAY_W;
1077	our $PID_IDLE;
1078	our $WNOHANG;	1381	our $WNOHANG;
1079		1382
1080	sub _child_wait {	1383	sub _sigchld {
1081	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1384	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1385	$_->($pid, $?)
1082	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1386	for values %{ $PID_CB{$pid} || {} },
1083	(values %{ $PID_CB{0} || {} });	1387	values %{ $PID_CB{0} || {} };
1084	}	1388	}
1085
1086	undef $PID_IDLE;
1087	}
1088
1089	sub _sigchld {
1090	# make sure we deliver these changes "synchronous" with the event loop.
1091	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1092	undef $CHLD_DELAY_W;
1093	&_child_wait;
1094	});
1095	}	1389	}
1096		1390
1097	sub child {	1391	sub child {
1098	my (undef, %arg) = @_;	1392	my (undef, %arg) = @_;
1099		1393
1100	defined (my $pid = $arg{pid} + 0)	1394	defined (my $pid = $arg{pid} + 0)
1101	or Carp::croak "required option 'pid' is missing";	1395	or Carp::croak "required option 'pid' is missing";
1102		1396
1103	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1397	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1104		1398
1105	unless ($WNOHANG) {	1399	# WNOHANG is almost cetrainly 1 everywhere
		1400	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1401	? 1
1106	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1402	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1107	}
1108		1403
1109	unless ($CHLD_W) {	1404	unless ($CHLD_W) {
1110	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1405	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1111	# child could be a zombie already, so make at least one round	1406	# child could be a zombie already, so make at least one round
1112	&_sigchld;	1407	&_sigchld;
1113	}	1408	}
1114		1409
1115	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1410	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1116	}	1411	}
1117		1412
1118	sub AnyEvent::Base::Child::DESTROY {	1413	sub AnyEvent::Base::child::DESTROY {
1119	my ($pid, $cb) = @{$_[0]};	1414	my ($pid, $cb) = @{$_[0]};
1120		1415
1121	delete $PID_CB{$pid}{$cb};	1416	delete $PID_CB{$pid}{$cb};
1122	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1417	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1123		1418
1124	undef $CHLD_W unless keys %PID_CB;	1419	undef $CHLD_W unless keys %PID_CB;
1125	}	1420	}
1126		1421
		1422	# idle emulation is done by simply using a timer, regardless
		1423	# of whether the process is idle or not, and not letting
		1424	# the callback use more than 50% of the time.
		1425	sub idle {
		1426	my (undef, %arg) = @_;
		1427
		1428	my ($cb, $w, $rcb) = $arg{cb};
		1429
		1430	$rcb = sub {
		1431	if ($cb) {
		1432	$w = _time;
		1433	&$cb;
		1434	$w = _time - $w;
		1435
		1436	# never use more then 50% of the time for the idle watcher,
		1437	# within some limits
		1438	$w = 0.0001 if $w < 0.0001;
		1439	$w = 5 if $w > 5;
		1440
		1441	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1442	} else {
		1443	# clean up...
		1444	undef $w;
		1445	undef $rcb;
		1446	}
		1447	};
		1448
		1449	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1450
		1451	bless \\$cb, "AnyEvent::Base::idle"
		1452	}
		1453
		1454	sub AnyEvent::Base::idle::DESTROY {
		1455	undef $${$_[0]};
		1456	}
		1457
1127	package AnyEvent::CondVar;	1458	package AnyEvent::CondVar;
1128		1459
1129	our @ISA = AnyEvent::CondVar::Base::;	1460	our @ISA = AnyEvent::CondVar::Base::;
1130		1461
1131	package AnyEvent::CondVar::Base;	1462	package AnyEvent::CondVar::Base;
1132		1463
1133	use overload	1464	#use overload
1134	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1465	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1135	fallback => 1;	1466	# fallback => 1;
		1467
		1468	# save 300+ kilobytes by dirtily hardcoding overloading
		1469	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1470	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1471	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1472	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1473
		1474	our $WAITING;
1136		1475
1137	sub _send {	1476	sub _send {
1138	# nop	1477	# nop
1139	}	1478	}
1140		1479
…		…
1153	sub ready {	1492	sub ready {
1154	$_[0]{_ae_sent}	1493	$_[0]{_ae_sent}
1155	}	1494	}
1156		1495
1157	sub _wait {	1496	sub _wait {
		1497	$WAITING
		1498	and !$_[0]{_ae_sent}
		1499	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1500
		1501	local $WAITING = 1;
1158	AnyEvent->one_event while !$_[0]{_ae_sent};	1502	AnyEvent->one_event while !$_[0]{_ae_sent};
1159	}	1503	}
1160		1504
1161	sub recv {	1505	sub recv {
1162	$_[0]->_wait;	1506	$_[0]->_wait;
…		…
1203	so on.	1547	so on.
1204		1548
1205	=head1 ENVIRONMENT VARIABLES	1549	=head1 ENVIRONMENT VARIABLES
1206		1550
1207	The following environment variables are used by this module or its	1551	The following environment variables are used by this module or its
1208	submodules:	1552	submodules.
		1553
		1554	Note that AnyEvent will remove I<all> environment variables starting with
		1555	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1556	enabled.
1209		1557
1210	=over 4	1558	=over 4
1211		1559
1212	=item C<PERL_ANYEVENT_VERBOSE>	1560	=item C<PERL_ANYEVENT_VERBOSE>
1213		1561
…		…
1220	C<PERL_ANYEVENT_MODEL>.	1568	C<PERL_ANYEVENT_MODEL>.
1221		1569
1222	When set to C<2> or higher, cause AnyEvent to report to STDERR which event	1570	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1223	model it chooses.	1571	model it chooses.
1224		1572
		1573	When set to C<8> or higher, then AnyEvent will report extra information on
		1574	which optional modules it loads and how it implements certain features.
		1575
1225	=item C<PERL_ANYEVENT_STRICT>	1576	=item C<PERL_ANYEVENT_STRICT>
1226		1577
1227	AnyEvent does not do much argument checking by default, as thorough	1578	AnyEvent does not do much argument checking by default, as thorough
1228	argument checking is very costly. Setting this variable to a true value	1579	argument checking is very costly. Setting this variable to a true value
1229	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly	1580	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1230	check the arguments passed to most method calls. If it finds any problems	1581	check the arguments passed to most method calls. If it finds any problems,
1231	it will croak.	1582	it will croak.
1232		1583
1233	In other words, enables "strict" mode.	1584	In other words, enables "strict" mode.
1234		1585
1235	Unlike C<use strict>, it is definitely recommended ot keep it off in	1586	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
1236	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while	1587	>>, it is definitely recommended to keep it off in production. Keeping
1237	developing programs can be very useful, however.	1588	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1589	can be very useful, however.
1238		1590
1239	=item C<PERL_ANYEVENT_MODEL>	1591	=item C<PERL_ANYEVENT_MODEL>
1240		1592
1241	This can be used to specify the event model to be used by AnyEvent, before	1593	This can be used to specify the event model to be used by AnyEvent, before
1242	auto detection and -probing kicks in. It must be a string consisting	1594	auto detection and -probing kicks in. It must be a string consisting
…		…
1263	used, and preference will be given to protocols mentioned earlier in the	1615	used, and preference will be given to protocols mentioned earlier in the
1264	list.	1616	list.
1265		1617
1266	This variable can effectively be used for denial-of-service attacks	1618	This variable can effectively be used for denial-of-service attacks
1267	against local programs (e.g. when setuid), although the impact is likely	1619	against local programs (e.g. when setuid), although the impact is likely
1268	small, as the program has to handle connection errors already-	1620	small, as the program has to handle conenction and other failures anyways.
1269		1621
1270	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,	1622	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1271	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>	1623	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1272	- only support IPv4, never try to resolve or contact IPv6	1624	- only support IPv4, never try to resolve or contact IPv6
1273	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or	1625	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
…		…
1285		1637
1286	=item C<PERL_ANYEVENT_MAX_FORKS>	1638	=item C<PERL_ANYEVENT_MAX_FORKS>
1287		1639
1288	The maximum number of child processes that C<AnyEvent::Util::fork_call>	1640	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1289	will create in parallel.	1641	will create in parallel.
		1642
		1643	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1644
		1645	The default value for the C<max_outstanding> parameter for the default DNS
		1646	resolver - this is the maximum number of parallel DNS requests that are
		1647	sent to the DNS server.
		1648
		1649	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1650
		1651	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1652	configuration) in the default resolver. When set to the empty string, no
		1653	default config will be used.
		1654
		1655	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1656
		1657	When neither C<ca_file> nor C<ca_path> was specified during
		1658	L<AnyEvent::TLS> context creation, and either of these environment
		1659	variables exist, they will be used to specify CA certificate locations
		1660	instead of a system-dependent default.
		1661
		1662	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1663
		1664	When these are set to C<1>, then the respective modules are not
		1665	loaded. Mostly good for testing AnyEvent itself.
1290		1666
1291	=back	1667	=back
1292		1668
1293	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1669	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1294		1670
…		…
1539	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers	1915	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1540	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal	1916	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1541	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation	1917	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1542	Event/Event 16000 517 32.20 31.80 0.81 Event native interface	1918	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1543	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers	1919	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1920	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1921	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1544	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour	1922	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1545	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers	1923	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1546	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event	1924	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1547	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select	1925	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1548		1926
…		…
1577	performance becomes really bad with lots of file descriptors (and few of	1955	performance becomes really bad with lots of file descriptors (and few of
1578	them active), of course, but this was not subject of this benchmark.	1956	them active), of course, but this was not subject of this benchmark.
1579		1957
1580	The C<Event> module has a relatively high setup and callback invocation	1958	The C<Event> module has a relatively high setup and callback invocation
1581	cost, but overall scores in on the third place.	1959	cost, but overall scores in on the third place.
		1960
		1961	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1962	when using its pure perl backend.
1582		1963
1583	C<Glib>'s memory usage is quite a bit higher, but it features a	1964	C<Glib>'s memory usage is quite a bit higher, but it features a
1584	faster callback invocation and overall ends up in the same class as	1965	faster callback invocation and overall ends up in the same class as
1585	C<Event>. However, Glib scales extremely badly, doubling the number of	1966	C<Event>. However, Glib scales extremely badly, doubling the number of
1586	watchers increases the processing time by more than a factor of four,	1967	watchers increases the processing time by more than a factor of four,
…		…
1664	it to another server. This includes deleting the old timeout and creating	2045	it to another server. This includes deleting the old timeout and creating
1665	a new one that moves the timeout into the future.	2046	a new one that moves the timeout into the future.
1666		2047
1667	=head3 Results	2048	=head3 Results
1668		2049
1669	name sockets create request	2050	name sockets create request
1670	EV 20000 69.01 11.16	2051	EV 20000 69.01 11.16
1671	Perl 20000 73.32 35.87	2052	Perl 20000 73.32 35.87
		2053	IOAsync 20000 157.00 98.14 epoll
		2054	IOAsync 20000 159.31 616.06 poll
1672	Event 20000 212.62 257.32	2055	Event 20000 212.62 257.32
1673	Glib 20000 651.16 1896.30	2056	Glib 20000 651.16 1896.30
1674	POE 20000 349.67 12317.24 uses POE::Loop::Event	2057	POE 20000 349.67 12317.24 uses POE::Loop::Event
1675		2058
1676	=head3 Discussion	2059	=head3 Discussion
1677		2060
1678	This benchmark I<does> measure scalability and overall performance of the	2061	This benchmark I<does> measure scalability and overall performance of the
1679	particular event loop.	2062	particular event loop.
…		…
1681	EV is again fastest. Since it is using epoll on my system, the setup time	2064	EV is again fastest. Since it is using epoll on my system, the setup time
1682	is relatively high, though.	2065	is relatively high, though.
1683		2066
1684	Perl surprisingly comes second. It is much faster than the C-based event	2067	Perl surprisingly comes second. It is much faster than the C-based event
1685	loops Event and Glib.	2068	loops Event and Glib.
		2069
		2070	IO::Async performs very well when using its epoll backend, and still quite
		2071	good compared to Glib when using its pure perl backend.
1686		2072
1687	Event suffers from high setup time as well (look at its code and you will	2073	Event suffers from high setup time as well (look at its code and you will
1688	understand why). Callback invocation also has a high overhead compared to	2074	understand why). Callback invocation also has a high overhead compared to
1689	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2075	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1690	uses select or poll in basically all documented configurations.	2076	uses select or poll in basically all documented configurations.
…		…
1753	=item * C-based event loops perform very well with small number of	2139	=item * C-based event loops perform very well with small number of
1754	watchers, as the management overhead dominates.	2140	watchers, as the management overhead dominates.
1755		2141
1756	=back	2142	=back
1757		2143
		2144	=head2 THE IO::Lambda BENCHMARK
		2145
		2146	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2147	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2148	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2149	shouldn't come as a surprise to anybody). As such, the benchmark is
		2150	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2151	very optimal. But how would AnyEvent compare when used without the extra
		2152	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2153
		2154	The benchmark itself creates an echo-server, and then, for 500 times,
		2155	connects to the echo server, sends a line, waits for the reply, and then
		2156	creates the next connection. This is a rather bad benchmark, as it doesn't
		2157	test the efficiency of the framework or much non-blocking I/O, but it is a
		2158	benchmark nevertheless.
		2159
		2160	name runtime
		2161	Lambda/select 0.330 sec
		2162	+ optimized 0.122 sec
		2163	Lambda/AnyEvent 0.327 sec
		2164	+ optimized 0.138 sec
		2165	Raw sockets/select 0.077 sec
		2166	POE/select, components 0.662 sec
		2167	POE/select, raw sockets 0.226 sec
		2168	POE/select, optimized 0.404 sec
		2169
		2170	AnyEvent/select/nb 0.085 sec
		2171	AnyEvent/EV/nb 0.068 sec
		2172	+state machine 0.134 sec
		2173
		2174	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2175	benchmarks actually make blocking connects and use 100% blocking I/O,
		2176	defeating the purpose of an event-based solution. All of the newly
		2177	written AnyEvent benchmarks use 100% non-blocking connects (using
		2178	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2179	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2180	generally require a lot more bookkeeping and event handling than blocking
		2181	connects (which involve a single syscall only).
		2182
		2183	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2184	offers similar expressive power as POE and IO::Lambda, using conventional
		2185	Perl syntax. This means that both the echo server and the client are 100%
		2186	non-blocking, further placing it at a disadvantage.
		2187
		2188	As you can see, the AnyEvent + EV combination even beats the
		2189	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2190	backend easily beats IO::Lambda and POE.
		2191
		2192	And even the 100% non-blocking version written using the high-level (and
		2193	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2194	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2195	in a non-blocking way.
		2196
		2197	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2198	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2199	part of the IO::lambda distribution and were used without any changes.
		2200
1758		2201
1759	=head1 SIGNALS	2202	=head1 SIGNALS
1760		2203
1761	AnyEvent currently installs handlers for these signals:	2204	AnyEvent currently installs handlers for these signals:
1762		2205
…		…
1765	=item SIGCHLD	2208	=item SIGCHLD
1766		2209
1767	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher	2210	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
1768	emulation for event loops that do not support them natively. Also, some	2211	emulation for event loops that do not support them natively. Also, some
1769	event loops install a similar handler.	2212	event loops install a similar handler.
		2213
		2214	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2215	AnyEvent will reset it to default, to avoid losing child exit statuses.
1770		2216
1771	=item SIGPIPE	2217	=item SIGPIPE
1772		2218
1773	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>	2219	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
1774	when AnyEvent gets loaded.	2220	when AnyEvent gets loaded.
…		…
1786		2232
1787	=back	2233	=back
1788		2234
1789	=cut	2235	=cut
1790		2236
		2237	undef $SIG{CHLD}
		2238	if $SIG{CHLD} eq 'IGNORE';
		2239
1791	$SIG{PIPE} = sub { }	2240	$SIG{PIPE} = sub { }
1792	unless defined $SIG{PIPE};	2241	unless defined $SIG{PIPE};
		2242
		2243	=head1 RECOMMENDED/OPTIONAL MODULES
		2244
		2245	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2246	it's built-in modules) are required to use it.
		2247
		2248	That does not mean that AnyEvent won't take advantage of some additional
		2249	modules if they are installed.
		2250
		2251	This section epxlains which additional modules will be used, and how they
		2252	affect AnyEvent's operetion.
		2253
		2254	=over 4
		2255
		2256	=item L<Async::Interrupt>
		2257
		2258	This slightly arcane module is used to implement fast signal handling: To
		2259	my knowledge, there is no way to do completely race-free and quick
		2260	signal handling in pure perl. To ensure that signals still get
		2261	delivered, AnyEvent will start an interval timer to wake up perl (and
		2262	catch the signals) with soemd elay (default is 10 seconds, look for
		2263	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2264
		2265	If this module is available, then it will be used to implement signal
		2266	catching, which means that signals will not be delayed, and the event loop
		2267	will not be interrupted regularly, which is more efficient (And good for
		2268	battery life on laptops).
		2269
		2270	This affects not just the pure-perl event loop, but also other event loops
		2271	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2272
		2273	=item L<EV>
		2274
		2275	This module isn't really "optional", as it is simply one of the backend
		2276	event loops that AnyEvent can use. However, it is simply the best event
		2277	loop available in terms of features, speed and stability: It supports
		2278	the AnyEvent API optimally, implements all the watcher types in XS, does
		2279	automatic timer adjustments even when no monotonic clock is available,
		2280	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2281	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2282	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2283
		2284	=item L<Guard>
		2285
		2286	The guard module, when used, will be used to implement
		2287	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2288	lot less memory), but otherwise doesn't affect guard operation much. It is
		2289	purely used for performance.
		2290
		2291	=item L<JSON> and L<JSON::XS>
		2292
		2293	This module is required when you want to read or write JSON data via
		2294	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2295	advantage of the ulta-high-speed L<JSON::XS> module when it is installed.
		2296
		2297	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2298	installed.
		2299
		2300	=item L<Net::SSLeay>
		2301
		2302	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2303	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2304	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2305
		2306	=item L<Time::HiRes>
		2307
		2308	This module is part of perl since release 5.008. It will be used when the
		2309	chosen event library does not come with a timing source on it's own. The
		2310	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2311	try to use a monotonic clock for timing stability.
		2312
		2313	=back
1793		2314
1794		2315
1795	=head1 FORK	2316	=head1 FORK
1796		2317
1797	Most event libraries are not fork-safe. The ones who are usually are	2318	Most event libraries are not fork-safe. The ones who are usually are
1798	because they rely on inefficient but fork-safe C<select> or C<poll>	2319	because they rely on inefficient but fork-safe C<select> or C<poll>
1799	calls. Only L<EV> is fully fork-aware.	2320	calls. Only L<EV> is fully fork-aware.
1800		2321
1801	If you have to fork, you must either do so I<before> creating your first	2322	If you have to fork, you must either do so I<before> creating your first
1802	watcher OR you must not use AnyEvent at all in the child.	2323	watcher OR you must not use AnyEvent at all in the child OR you must do
		2324	something completely out of the scope of AnyEvent.
1803		2325
1804		2326
1805	=head1 SECURITY CONSIDERATIONS	2327	=head1 SECURITY CONSIDERATIONS
1806		2328
1807	AnyEvent can be forced to load any event model via	2329	AnyEvent can be forced to load any event model via
…		…
1819	use AnyEvent;	2341	use AnyEvent;
1820		2342
1821	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2343	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1822	be used to probe what backend is used and gain other information (which is	2344	be used to probe what backend is used and gain other information (which is
1823	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2345	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1824	$ENV{PERL_ANYEGENT_STRICT}.	2346	$ENV{PERL_ANYEVENT_STRICT}.
		2347
		2348	Note that AnyEvent will remove I<all> environment variables starting with
		2349	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2350	enabled.
1825		2351
1826		2352
1827	=head1 BUGS	2353	=head1 BUGS
1828		2354
1829	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2355	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1830	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2356	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1831	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2357	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1832	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2358	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1833	pronounced).	2359	pronounced).
1834		2360
1835		2361
1836	=head1 SEE ALSO	2362	=head1 SEE ALSO
1837		2363
…		…
1841	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2367	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1842		2368
1843	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2369	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1844	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2370	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1845	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2371	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1846	L<AnyEvent::Impl::POE>.	2372	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1847		2373
1848	Non-blocking file handles, sockets, TCP clients and	2374	Non-blocking file handles, sockets, TCP clients and
1849	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2375	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1850		2376
1851	Asynchronous DNS: L<AnyEvent::DNS>.	2377	Asynchronous DNS: L<AnyEvent::DNS>.
1852		2378
1853	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2379	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2380	L<Coro::Event>,
1854		2381
1855	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2382	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2383	L<AnyEvent::HTTP>.
1856		2384
1857		2385
1858	=head1 AUTHOR	2386	=head1 AUTHOR
1859		2387
1860	Marc Lehmann <schmorp@schmorp.de>	2388	Marc Lehmann <schmorp@schmorp.de>

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