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Revision 1.179 by root, Thu Sep 4 10:58:58 2008 UTC vs.
Revision 1.243 by root, Fri Jul 17 23:12:20 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
340	=head2 CHILD PROCESS WATCHERS	388	=head2 CHILD PROCESS WATCHERS
341		389
342	You can also watch on a child process exit and catch its exit status.	390	You can also watch on a child process exit and catch its exit status.
343		391
344	The child process is specified by the C<pid> argument (if set to C<0>, it	392	The child process is specified by the C<pid> argument (if set to C<0>, it
345	watches for any child process exit). The watcher will trigger as often	393	watches for any child process exit). The watcher will triggered only when
346	as status change for the child are received. This works by installing a	394	the child process has finished and an exit status is available, not on
347	signal handler for C<SIGCHLD>. The callback will be called with the pid	395	any trace events (stopped/continued).
348	and exit status (as returned by waitpid), so unlike other watcher types,	396
349	you I<can> rely on child watcher callback arguments.	397	The callback will be called with the pid and exit status (as returned by
		398	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		399	callback arguments.
		400
		401	This watcher type works by installing a signal handler for C<SIGCHLD>,
		402	and since it cannot be shared, nothing else should use SIGCHLD or reap
		403	random child processes (waiting for specific child processes, e.g. inside
		404	C<system>, is just fine).
350		405
351	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
352	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
353	have exited already (and no SIGCHLD will be sent anymore).	408	have exited already (and no SIGCHLD will be sent anymore).
354		409
355	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
356	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
357	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.
358		416
359	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
360	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
361	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.
362		425
363	Example: fork a process and wait for it	426	Example: fork a process and wait for it
364		427
365	my $done = AnyEvent->condvar;	428	my $done = AnyEvent->condvar;
366		429
…		…
376	);	439	);
377		440
378	# do something else, then wait for process exit	441	# do something else, then wait for process exit
379	$done->recv;	442	$done->recv;
380		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
381	=head2 CONDITION VARIABLES	479	=head2 CONDITION VARIABLES
382		480
383	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
384	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
385	will actively watch for new events and call your callbacks.	483	will actively watch for new events and call your callbacks.
386		484
387	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
388	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).
389		487
390	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
391	because they represent a condition that must become true.	489	because they represent a condition that must become true.
392		490
		491	Now is probably a good time to look at the examples further below.
		492
393	Condition variables can be created by calling the C<< AnyEvent->condvar	493	Condition variables can be created by calling the C<< AnyEvent->condvar
394	>> method, usually without arguments. The only argument pair allowed is	494	>> method, usually without arguments. The only argument pair allowed is
395
396	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
397	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
398	the results).	497	the results).
399		498
400	After creation, the condition variable is "false" until it becomes "true"	499	After creation, the condition variable is "false" until it becomes "true"
…		…
449	after => 1,	548	after => 1,
450	cb => sub { $result_ready->send },	549	cb => sub { $result_ready->send },
451	);	550	);
452		551
453	# this "blocks" (while handling events) till the callback	552	# this "blocks" (while handling events) till the callback
454	# calls send	553	# calls -<send
455	$result_ready->recv;	554	$result_ready->recv;
456		555
457	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
458	condition variables are also code references.	557	variables are also callable directly.
459		558
460	my $done = AnyEvent->condvar;	559	my $done = AnyEvent->condvar;
461	my $delay = AnyEvent->timer (after => 5, cb => $done);	560	my $delay = AnyEvent->timer (after => 5, cb => $done);
462	$done->recv;	561	$done->recv;
463		562
…		…
469		568
470	...	569	...
471		570
472	my @info = $couchdb->info->recv;	571	my @info = $couchdb->info->recv;
473		572
474	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
475	results are available:	574	results are available:
476		575
477	$couchdb->info->cb (sub {	576	$couchdb->info->cb (sub {
478	my @info = $_[0]->recv;	577	my @info = $_[0]->recv;
479	});	578	});
…		…
497	immediately from within send.	596	immediately from within send.
498		597
499	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
500	future C<< ->recv >> calls.	599	future C<< ->recv >> calls.
501		600
502	Condition variables are overloaded so one can call them directly	601	Condition variables are overloaded so one can call them directly (as if
503	(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
504	C<send>. Note, however, that many C-based event loops do not handle	603	C<send>.
505	overloading, so as tempting as it may be, passing a condition variable
506	instead of a callback does not work. Both the pure perl and EV loops
507	support overloading, however, as well as all functions that use perl to
508	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
509	example).
510		604
511	=item $cv->croak ($error)	605	=item $cv->croak ($error)
512		606
513	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
514	C<Carp::croak> with the given error message/object/scalar.	608	C<Carp::croak> with the given error message/object/scalar.
515		609
516	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
517	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.
518		616
519	=item $cv->begin ([group callback])	617	=item $cv->begin ([group callback])
520		618
521	=item $cv->end	619	=item $cv->end
522
523	These two methods are EXPERIMENTAL and MIGHT CHANGE.
524		620
525	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
526	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
527	to use a condition variable for the whole process.	623	to use a condition variable for the whole process.
528		624
…		…
530	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
531	>>, 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
532	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
533	callback was set, C<send> will be called without any arguments.	629	callback was set, C<send> will be called without any arguments.
534		630
535	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:
536		662
537	my $cv = AnyEvent->condvar;	663	my $cv = AnyEvent->condvar;
538		664
539	my %result;	665	my %result;
540	$cv->begin (sub { $cv->send (\%result) });	666	$cv->begin (sub { $cv->send (\%result) });
…		…
560	loop, which serves two important purposes: first, it sets the callback	686	loop, which serves two important purposes: first, it sets the callback
561	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
562	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
563	doesn't execute once).	689	doesn't execute once).
564		690
565	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
566	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
567	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
568	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>.
569		696
570	=back	697	=back
571		698
572	=head3 METHODS FOR CONSUMERS	699	=head3 METHODS FOR CONSUMERS
573		700
…		…
589	function will call C<croak>.	716	function will call C<croak>.
590		717
591	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,
592	in scalar context only the first one will be returned.	719	in scalar context only the first one will be returned.
593		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
594	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
595	(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
596	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
597	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
598	condition variables with some kind of request results and supporting	732	condition variables with some kind of request results and supporting
599	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,
600	while still supporting blocking waits if the caller so desires).	734	while still supporting blocking waits if the caller so desires).
601		735
602	Another reason I<never> to C<< ->recv >> in a module is that you cannot
603	sensibly have two C<< ->recv >>'s in parallel, as that would require
604	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
605	can supply.
606
607	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
608	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
609	versions and also integrates coroutines into AnyEvent, making blocking
610	C<< ->recv >> calls perfectly safe as long as they are done from another
611	coroutine (one that doesn't run the event loop).
612
613	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
614	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
615	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
616	waits otherwise.	739	waits otherwise.
617		740
…		…
630	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
631	is guaranteed not to block.	754	is guaranteed not to block.
632		755
633	=back	756	=back
634		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
635	=head1 GLOBAL VARIABLES AND FUNCTIONS	825	=head1 GLOBAL VARIABLES AND FUNCTIONS
636		826
		827	These are not normally required to use AnyEvent, but can be useful to
		828	write AnyEvent extension modules.
		829
637	=over 4	830	=over 4
638		831
639	=item $AnyEvent::MODEL	832	=item $AnyEvent::MODEL
640		833
641	Contains C<undef> until the first watcher is being created. Then it	834	Contains C<undef> until the first watcher is being created, before the
		835	backend has been autodetected.
		836
642	contains the event model that is being used, which is the name of the	837	Afterwards it contains the event model that is being used, which is the
643	Perl class implementing the model. This class is usually one of the	838	name of the Perl class implementing the model. This class is usually one
644	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	839	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
645	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	840	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
646		841	will be C<urxvt::anyevent>).
647	The known classes so far are:
648
649	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
650	AnyEvent::Impl::Event based on Event, second best choice.
651	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
652	AnyEvent::Impl::Glib based on Glib, third-best choice.
653	AnyEvent::Impl::Tk based on Tk, very bad choice.
654	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
655	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
656	AnyEvent::Impl::POE based on POE, not generic enough for full support.
657
658	There is no support for WxWidgets, as WxWidgets has no support for
659	watching file handles. However, you can use WxWidgets through the
660	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
661	second, which was considered to be too horrible to even consider for
662	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
663	it's adaptor.
664
665	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
666	autodetecting them.
667		842
668	=item AnyEvent::detect	843	=item AnyEvent::detect
669		844
670	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	845	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
671	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
672	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
673	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>.
674		852
675	=item $guard = AnyEvent::post_detect { BLOCK }	853	=item $guard = AnyEvent::post_detect { BLOCK }
676		854
677	Arranges for the code block to be executed as soon as the event model is	855	Arranges for the code block to be executed as soon as the event model is
678	autodetected (or immediately if this has already happened).	856	autodetected (or immediately if this has already happened).
		857
		858	The block will be executed I<after> the actual backend has been detected
		859	(C<$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.
679		868
680	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
681	that automatically removes the callback again when it is destroyed. See	870	that automatically removes the callback again when it is destroyed. See
682	L<Coro::BDB> for a case where this is useful.	871	L<Coro::BDB> for a case where this is useful.
683		872
…		…
686	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
687	before or after loading AnyEvent), then they will called directly after	876	before or after loading AnyEvent), then they will called directly after
688	the event loop has been chosen.	877	the event loop has been chosen.
689		878
690	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:
691	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
692	and the array will be ignored.	881	array will be ignored.
693		882
694	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.
695		890
696	=back	891	=back
697		892
698	=head1 WHAT TO DO IN A MODULE	893	=head1 WHAT TO DO IN A MODULE
699		894
…		…
754		949
755		950
756	=head1 OTHER MODULES	951	=head1 OTHER MODULES
757		952
758	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
759	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
760	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
761	available via CPAN.	956	come with AnyEvent, most are available via CPAN.
762		957
763	=over 4	958	=over 4
764		959
765	=item L<AnyEvent::Util>	960	=item L<AnyEvent::Util>
766		961
…		…
775		970
776	=item L<AnyEvent::Handle>	971	=item L<AnyEvent::Handle>
777		972
778	Provide read and write buffers, manages watchers for reads and writes,	973	Provide read and write buffers, manages watchers for reads and writes,
779	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
780	non-blocking SSL/TLS.	975	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
781		976
782	=item L<AnyEvent::DNS>	977	=item L<AnyEvent::DNS>
783		978
784	Provides rich asynchronous DNS resolver capabilities.	979	Provides rich asynchronous DNS resolver capabilities.
785		980
…		…
813		1008
814	=item L<AnyEvent::GPSD>	1009	=item L<AnyEvent::GPSD>
815		1010
816	A non-blocking interface to gpsd, a daemon delivering GPS information.	1011	A non-blocking interface to gpsd, a daemon delivering GPS information.
817		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
818	=item L<AnyEvent::IGS>	1022	=item L<AnyEvent::IGS>
819		1023
820	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
821	L<App::IGS>).	1025	L<App::IGS>).
822		1026
823	=item L<Net::IRC3>
824
825	AnyEvent based IRC client module family.
826
827	=item L<Net::XMPP2>
828
829	AnyEvent based XMPP (Jabber protocol) module family.
830
831	=item L<Net::FCP>	1027	=item L<Net::FCP>
832		1028
833	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1029	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
834	of AnyEvent.	1030	of AnyEvent.
835		1031
…		…
839		1035
840	=item L<Coro>	1036	=item L<Coro>
841		1037
842	Has special support for AnyEvent via L<Coro::AnyEvent>.	1038	Has special support for AnyEvent via L<Coro::AnyEvent>.
843		1039
844	=item L<IO::Lambda>
845
846	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
847
848	=back	1040	=back
849		1041
850	=cut	1042	=cut
851		1043
852	package AnyEvent;	1044	package AnyEvent;
853		1045
		1046	# basically a tuned-down version of common::sense
		1047	sub common_sense {
854	no warnings;	1048	# no warnings
855	use strict;	1049	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1050	# use strict vars subs
		1051	$^H |= 0x00000600;
		1052	}
856		1053
		1054	BEGIN { AnyEvent::common_sense }
		1055
857	use Carp;	1056	use Carp ();
858		1057
859	our $VERSION = 4.233;	1058	our $VERSION = 4.83;
860	our $MODEL;	1059	our $MODEL;
861		1060
862	our $AUTOLOAD;	1061	our $AUTOLOAD;
863	our @ISA;	1062	our @ISA;
864		1063
865	our @REGISTRY;	1064	our @REGISTRY;
866		1065
867	our $WIN32;	1066	our $WIN32;
868		1067
		1068	our $VERBOSE;
		1069
869	BEGIN {	1070	BEGIN {
870	my $win32 = ! ! ($^O =~ /mswin32/i);	1071	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
871	eval "sub WIN32(){ $win32 }";	1072	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
872	}
873		1073
		1074	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1075	if ${^TAINT};
		1076
874	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1077	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1078
		1079	}
		1080
		1081	our $MAX_SIGNAL_LATENCY = 10;
875		1082
876	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1083	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
877		1084
878	{	1085	{
879	my $idx;	1086	my $idx;
…		…
887	[Event:: => AnyEvent::Impl::Event::],	1094	[Event:: => AnyEvent::Impl::Event::],
888	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1095	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
889	# everything below here will not be autoprobed	1096	# everything below here will not be autoprobed
890	# as the pureperl backend should work everywhere	1097	# as the pureperl backend should work everywhere
891	# and is usually faster	1098	# and is usually faster
892	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
893	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1099	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
894	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1100	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1101	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
895	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1102	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
896	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1103	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
897	[Wx:: => AnyEvent::Impl::POE::],	1104	[Wx:: => AnyEvent::Impl::POE::],
898	[Prima:: => AnyEvent::Impl::POE::],	1105	[Prima:: => AnyEvent::Impl::POE::],
		1106	# IO::Async is just too broken - we would need workarounds for its
		1107	# byzantine signal and broken child handling, among others.
		1108	# IO::Async is rather hard to detect, as it doesn't have any
		1109	# obvious default class.
		1110	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1111	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1112	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
899	);	1113	);
900		1114
901	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1115	our %method = map +($_ => 1),
		1116	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
902		1117
903	our @post_detect;	1118	our @post_detect;
904		1119
905	sub post_detect(&) {	1120	sub post_detect(&) {
906	my ($cb) = @_;	1121	my ($cb) = @_;
…		…
911	1	1126	1
912	} else {	1127	} else {
913	push @post_detect, $cb;	1128	push @post_detect, $cb;
914		1129
915	defined wantarray	1130	defined wantarray
916	? bless \$cb, "AnyEvent::Util::PostDetect"	1131	? bless \$cb, "AnyEvent::Util::postdetect"
917	: ()	1132	: ()
918	}	1133	}
919	}	1134	}
920		1135
921	sub AnyEvent::Util::PostDetect::DESTROY {	1136	sub AnyEvent::Util::postdetect::DESTROY {
922	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1137	@post_detect = grep $_ != ${$_[0]}, @post_detect;
923	}	1138	}
924		1139
925	sub detect() {	1140	sub detect() {
926	unless ($MODEL) {	1141	unless ($MODEL) {
927	no strict 'refs';
928	local $SIG{__DIE__};	1142	local $SIG{__DIE__};
929		1143
930	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1144	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
931	my $model = "AnyEvent::Impl::$1";	1145	my $model = "AnyEvent::Impl::$1";
932	if (eval "require $model") {	1146	if (eval "require $model") {
933	$MODEL = $model;	1147	$MODEL = $model;
934	warn "AnyEvent: loaded model '$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 $VERBOSE >= 2;
935	} else {	1149	} else {
936	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1150	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
937	}	1151	}
938	}	1152	}
939		1153
940	# check for already loaded models	1154	# check for already loaded models
941	unless ($MODEL) {	1155	unless ($MODEL) {
942	for (@REGISTRY, @models) {	1156	for (@REGISTRY, @models) {
943	my ($package, $model) = @$_;	1157	my ($package, $model) = @$_;
944	if (${"$package\::VERSION"} > 0) {	1158	if (${"$package\::VERSION"} > 0) {
945	if (eval "require $model") {	1159	if (eval "require $model") {
946	$MODEL = $model;	1160	$MODEL = $model;
947	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1161	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
948	last;	1162	last;
949	}	1163	}
950	}	1164	}
951	}	1165	}
952		1166
…		…
957	my ($package, $model) = @$_;	1171	my ($package, $model) = @$_;
958	if (eval "require $package"	1172	if (eval "require $package"
959	and ${"$package\::VERSION"} > 0	1173	and ${"$package\::VERSION"} > 0
960	and eval "require $model") {	1174	and eval "require $model") {
961	$MODEL = $model;	1175	$MODEL = $model;
962	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1176	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
963	last;	1177	last;
964	}	1178	}
965	}	1179	}
966		1180
967	$MODEL	1181	$MODEL
968	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1182	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
969	}	1183	}
970	}	1184	}
971		1185
972	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1186	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
973		1187
…		…
983		1197
984	sub AUTOLOAD {	1198	sub AUTOLOAD {
985	(my $func = $AUTOLOAD) =~ s/.*://;	1199	(my $func = $AUTOLOAD) =~ s/.*://;
986		1200
987	$method{$func}	1201	$method{$func}
988	or croak "$func: not a valid method for AnyEvent objects";	1202	or Carp::croak "$func: not a valid method for AnyEvent objects";
989		1203
990	detect unless $MODEL;	1204	detect unless $MODEL;
991		1205
992	my $class = shift;	1206	my $class = shift;
993	$class->$func (@_);	1207	$class->$func (@_);
994	}	1208	}
995		1209
996	# 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
997	# to support binding more than one watcher per filehandle (they usually	1211	# to support binding more than one watcher per filehandle (they usually
998	# 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).
999	sub _dupfh($$$$) {	1213	sub _dupfh($$;$$) {
1000	my ($poll, $fh, $r, $w) = @_;	1214	my ($poll, $fh, $r, $w) = @_;
1001		1215
1002	require Fcntl;
1003
1004	# cygwin requires the fh mode to be matching, unix doesn't	1216	# cygwin requires the fh mode to be matching, unix doesn't
1005	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1217	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1006	: $poll eq "w" ? ($w, ">")
1007	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1008		1218
1009	open my $fh2, "$mode&" . fileno $fh	1219	open my $fh2, $mode, $fh
1010	or die "cannot dup() filehandle: $!";	1220	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1011		1221
1012	# 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
1013		1223
1014	($fh2, $rw)	1224	($fh2, $rw)
1015	}	1225	}
1016		1226
1017	package AnyEvent::Base;	1227	package AnyEvent::Base;
1018		1228
1019	# default implementation for now and time	1229	# default implementations for many methods
1020		1230
1021	BEGIN {	1231	sub _time {
		1232	# probe for availability of Time::HiRes
1022	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;
1023	*_time = \&Time::HiRes::time;	1235	*_time = \&Time::HiRes::time;
1024	# if (eval "use POSIX (); (POSIX::times())...	1236	# if (eval "use POSIX (); (POSIX::times())...
1025	} else {	1237	} else {
		1238	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
1026	*_time = \&CORE::time; # epic fail	1239	*_time = sub { time }; # epic fail
1027	}	1240	}
		1241
		1242	&_time
1028	}	1243	}
1029		1244
1030	sub time { _time }	1245	sub time { _time }
1031	sub now { _time }	1246	sub now { _time }
		1247	sub now_update { }
1032		1248
1033	# default implementation for ->condvar	1249	# default implementation for ->condvar
1034		1250
1035	sub condvar {	1251	sub condvar {
1036	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1252	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1037	}	1253	}
1038		1254
1039	# default implementation for ->signal	1255	# default implementation for ->signal
1040		1256
1041	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);
1042		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
1043	sub signal {	1275	sub _signal {
1044	my (undef, %arg) = @_;	1276	my (undef, %arg) = @_;
1045		1277
1046	my $signal = uc $arg{signal}	1278	my $signal = uc $arg{signal}
1047	or Carp::croak "required option 'signal' is missing";	1279	or Carp::croak "required option 'signal' is missing";
1048		1280
1049	$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
1050	$SIG{$signal} ||= sub {	1300	$SIG{$signal} ||= sub {
1051	$_->() 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	);
1052	};	1314	}
1053		1315
1054	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1316	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1055	}	1317	}
1056		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
1057	sub AnyEvent::Base::Signal::DESTROY {	1359	sub AnyEvent::Base::signal::DESTROY {
1058	my ($signal, $cb) = @{$_[0]};	1360	my ($signal, $cb) = @{$_[0]};
1059		1361
		1362	undef $SIG_TW
		1363	unless --$SIG_COUNT;
		1364
1060	delete $SIG_CB{$signal}{$cb};	1365	delete $SIG_CB{$signal}{$cb};
1061		1366
		1367	# delete doesn't work with older perls - they then
		1368	# print weird messages, or just unconditionally exit
		1369	# instead of getting the default action.
		1370	undef $SIG{$signal}
1062	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1371	unless keys %{ $SIG_CB{$signal} };
1063	}	1372	}
1064		1373
1065	# default implementation for ->child	1374	# default implementation for ->child
1066		1375
1067	our %PID_CB;	1376	our %PID_CB;
1068	our $CHLD_W;	1377	our $CHLD_W;
1069	our $CHLD_DELAY_W;	1378	our $CHLD_DELAY_W;
1070	our $PID_IDLE;
1071	our $WNOHANG;	1379	our $WNOHANG;
1072		1380
1073	sub _child_wait {	1381	sub _sigchld {
1074	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1382	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1383	$_->($pid, $?)
1075	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1384	for values %{ $PID_CB{$pid} || {} },
1076	(values %{ $PID_CB{0} || {} });	1385	values %{ $PID_CB{0} || {} };
1077	}	1386	}
1078
1079	undef $PID_IDLE;
1080	}
1081
1082	sub _sigchld {
1083	# make sure we deliver these changes "synchronous" with the event loop.
1084	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1085	undef $CHLD_DELAY_W;
1086	&_child_wait;
1087	});
1088	}	1387	}
1089		1388
1090	sub child {	1389	sub child {
1091	my (undef, %arg) = @_;	1390	my (undef, %arg) = @_;
1092		1391
1093	defined (my $pid = $arg{pid} + 0)	1392	defined (my $pid = $arg{pid} + 0)
1094	or Carp::croak "required option 'pid' is missing";	1393	or Carp::croak "required option 'pid' is missing";
1095		1394
1096	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1395	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1097		1396
1098	unless ($WNOHANG) {	1397	# WNOHANG is almost cetrainly 1 everywhere
		1398	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1399	? 1
1099	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1400	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1100	}
1101		1401
1102	unless ($CHLD_W) {	1402	unless ($CHLD_W) {
1103	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1403	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1104	# child could be a zombie already, so make at least one round	1404	# child could be a zombie already, so make at least one round
1105	&_sigchld;	1405	&_sigchld;
1106	}	1406	}
1107		1407
1108	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1408	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1109	}	1409	}
1110		1410
1111	sub AnyEvent::Base::Child::DESTROY {	1411	sub AnyEvent::Base::child::DESTROY {
1112	my ($pid, $cb) = @{$_[0]};	1412	my ($pid, $cb) = @{$_[0]};
1113		1413
1114	delete $PID_CB{$pid}{$cb};	1414	delete $PID_CB{$pid}{$cb};
1115	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1415	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1116		1416
1117	undef $CHLD_W unless keys %PID_CB;	1417	undef $CHLD_W unless keys %PID_CB;
1118	}	1418	}
1119		1419
		1420	# idle emulation is done by simply using a timer, regardless
		1421	# of whether the process is idle or not, and not letting
		1422	# the callback use more than 50% of the time.
		1423	sub idle {
		1424	my (undef, %arg) = @_;
		1425
		1426	my ($cb, $w, $rcb) = $arg{cb};
		1427
		1428	$rcb = sub {
		1429	if ($cb) {
		1430	$w = _time;
		1431	&$cb;
		1432	$w = _time - $w;
		1433
		1434	# never use more then 50% of the time for the idle watcher,
		1435	# within some limits
		1436	$w = 0.0001 if $w < 0.0001;
		1437	$w = 5 if $w > 5;
		1438
		1439	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1440	} else {
		1441	# clean up...
		1442	undef $w;
		1443	undef $rcb;
		1444	}
		1445	};
		1446
		1447	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1448
		1449	bless \\$cb, "AnyEvent::Base::idle"
		1450	}
		1451
		1452	sub AnyEvent::Base::idle::DESTROY {
		1453	undef $${$_[0]};
		1454	}
		1455
1120	package AnyEvent::CondVar;	1456	package AnyEvent::CondVar;
1121		1457
1122	our @ISA = AnyEvent::CondVar::Base::;	1458	our @ISA = AnyEvent::CondVar::Base::;
1123		1459
1124	package AnyEvent::CondVar::Base;	1460	package AnyEvent::CondVar::Base;
1125		1461
1126	use overload	1462	#use overload
1127	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1463	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1128	fallback => 1;	1464	# fallback => 1;
		1465
		1466	# save 300+ kilobytes by dirtily hardcoding overloading
		1467	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1468	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1469	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1470	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1471
		1472	our $WAITING;
1129		1473
1130	sub _send {	1474	sub _send {
1131	# nop	1475	# nop
1132	}	1476	}
1133		1477
…		…
1146	sub ready {	1490	sub ready {
1147	$_[0]{_ae_sent}	1491	$_[0]{_ae_sent}
1148	}	1492	}
1149		1493
1150	sub _wait {	1494	sub _wait {
		1495	$WAITING
		1496	and !$_[0]{_ae_sent}
		1497	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1498
		1499	local $WAITING = 1;
1151	AnyEvent->one_event while !$_[0]{_ae_sent};	1500	AnyEvent->one_event while !$_[0]{_ae_sent};
1152	}	1501	}
1153		1502
1154	sub recv {	1503	sub recv {
1155	$_[0]->_wait;	1504	$_[0]->_wait;
…		…
1174	}	1523	}
1175		1524
1176	# undocumented/compatibility with pre-3.4	1525	# undocumented/compatibility with pre-3.4
1177	*broadcast = \&send;	1526	*broadcast = \&send;
1178	*wait = \&_wait;	1527	*wait = \&_wait;
		1528
		1529	=head1 ERROR AND EXCEPTION HANDLING
		1530
		1531	In general, AnyEvent does not do any error handling - it relies on the
		1532	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1533	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1534	checking of all AnyEvent methods, however, which is highly useful during
		1535	development.
		1536
		1537	As for exception handling (i.e. runtime errors and exceptions thrown while
		1538	executing a callback), this is not only highly event-loop specific, but
		1539	also not in any way wrapped by this module, as this is the job of the main
		1540	program.
		1541
		1542	The pure perl event loop simply re-throws the exception (usually
		1543	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1544	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1545	so on.
		1546
		1547	=head1 ENVIRONMENT VARIABLES
		1548
		1549	The following environment variables are used by this module or its
		1550	submodules.
		1551
		1552	Note that AnyEvent will remove I<all> environment variables starting with
		1553	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1554	enabled.
		1555
		1556	=over 4
		1557
		1558	=item C<PERL_ANYEVENT_VERBOSE>
		1559
		1560	By default, AnyEvent will be completely silent except in fatal
		1561	conditions. You can set this environment variable to make AnyEvent more
		1562	talkative.
		1563
		1564	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1565	conditions, such as not being able to load the event model specified by
		1566	C<PERL_ANYEVENT_MODEL>.
		1567
		1568	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1569	model it chooses.
		1570
		1571	=item C<PERL_ANYEVENT_STRICT>
		1572
		1573	AnyEvent does not do much argument checking by default, as thorough
		1574	argument checking is very costly. Setting this variable to a true value
		1575	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1576	check the arguments passed to most method calls. If it finds any problems,
		1577	it will croak.
		1578
		1579	In other words, enables "strict" mode.
		1580
		1581	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1582	>>, it is definitely recommended to keep it off in production. Keeping
		1583	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1584	can be very useful, however.
		1585
		1586	=item C<PERL_ANYEVENT_MODEL>
		1587
		1588	This can be used to specify the event model to be used by AnyEvent, before
		1589	auto detection and -probing kicks in. It must be a string consisting
		1590	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1591	and the resulting module name is loaded and if the load was successful,
		1592	used as event model. If it fails to load AnyEvent will proceed with
		1593	auto detection and -probing.
		1594
		1595	This functionality might change in future versions.
		1596
		1597	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1598	could start your program like this:
		1599
		1600	PERL_ANYEVENT_MODEL=Perl perl ...
		1601
		1602	=item C<PERL_ANYEVENT_PROTOCOLS>
		1603
		1604	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1605	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1606	of auto probing).
		1607
		1608	Must be set to a comma-separated list of protocols or address families,
		1609	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1610	used, and preference will be given to protocols mentioned earlier in the
		1611	list.
		1612
		1613	This variable can effectively be used for denial-of-service attacks
		1614	against local programs (e.g. when setuid), although the impact is likely
		1615	small, as the program has to handle conenction and other failures anyways.
		1616
		1617	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1618	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1619	- only support IPv4, never try to resolve or contact IPv6
		1620	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1621	IPv6, but prefer IPv6 over IPv4.
		1622
		1623	=item C<PERL_ANYEVENT_EDNS0>
		1624
		1625	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1626	for DNS. This extension is generally useful to reduce DNS traffic, but
		1627	some (broken) firewalls drop such DNS packets, which is why it is off by
		1628	default.
		1629
		1630	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1631	EDNS0 in its DNS requests.
		1632
		1633	=item C<PERL_ANYEVENT_MAX_FORKS>
		1634
		1635	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1636	will create in parallel.
		1637
		1638	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1639
		1640	The default value for the C<max_outstanding> parameter for the default DNS
		1641	resolver - this is the maximum number of parallel DNS requests that are
		1642	sent to the DNS server.
		1643
		1644	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1645
		1646	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1647	configuration) in the default resolver. When set to the empty string, no
		1648	default config will be used.
		1649
		1650	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1651
		1652	When neither C<ca_file> nor C<ca_path> was specified during
		1653	L<AnyEvent::TLS> context creation, and either of these environment
		1654	variables exist, they will be used to specify CA certificate locations
		1655	instead of a system-dependent default.
		1656
		1657	=back
1179		1658
1180	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1659	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1181		1660
1182	This is an advanced topic that you do not normally need to use AnyEvent in	1661	This is an advanced topic that you do not normally need to use AnyEvent in
1183	a module. This section is only of use to event loop authors who want to	1662	a module. This section is only of use to event loop authors who want to
…		…
1217		1696
1218	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1697	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1219	condition variables: code blocking while waiting for a condition will	1698	condition variables: code blocking while waiting for a condition will
1220	C<die>. This still works with most modules/usages, and blocking calls must	1699	C<die>. This still works with most modules/usages, and blocking calls must
1221	not be done in an interactive application, so it makes sense.	1700	not be done in an interactive application, so it makes sense.
1222
1223	=head1 ENVIRONMENT VARIABLES
1224
1225	The following environment variables are used by this module:
1226
1227	=over 4
1228
1229	=item C<PERL_ANYEVENT_VERBOSE>
1230
1231	By default, AnyEvent will be completely silent except in fatal
1232	conditions. You can set this environment variable to make AnyEvent more
1233	talkative.
1234
1235	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1236	conditions, such as not being able to load the event model specified by
1237	C<PERL_ANYEVENT_MODEL>.
1238
1239	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1240	model it chooses.
1241
1242	=item C<PERL_ANYEVENT_STRICT>
1243
1244	AnyEvent does not do much argument checking by default, as thorough
1245	argument checking is very costly. Setting this variable to a true value
1246	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1247	check the arguments passed to most method calls. If it finds any problems
1248	it will croak.
1249
1250	In other words, enables "strict" mode.
1251
1252	Unlike C<use strict> it is definitely recommended ot keep it off in
1253	production.
1254
1255	=item C<PERL_ANYEVENT_MODEL>
1256
1257	This can be used to specify the event model to be used by AnyEvent, before
1258	auto detection and -probing kicks in. It must be a string consisting
1259	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1260	and the resulting module name is loaded and if the load was successful,
1261	used as event model. If it fails to load AnyEvent will proceed with
1262	auto detection and -probing.
1263
1264	This functionality might change in future versions.
1265
1266	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1267	could start your program like this:
1268
1269	PERL_ANYEVENT_MODEL=Perl perl ...
1270
1271	=item C<PERL_ANYEVENT_PROTOCOLS>
1272
1273	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1274	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1275	of auto probing).
1276
1277	Must be set to a comma-separated list of protocols or address families,
1278	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1279	used, and preference will be given to protocols mentioned earlier in the
1280	list.
1281
1282	This variable can effectively be used for denial-of-service attacks
1283	against local programs (e.g. when setuid), although the impact is likely
1284	small, as the program has to handle connection errors already-
1285
1286	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1287	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1288	- only support IPv4, never try to resolve or contact IPv6
1289	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1290	IPv6, but prefer IPv6 over IPv4.
1291
1292	=item C<PERL_ANYEVENT_EDNS0>
1293
1294	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1295	for DNS. This extension is generally useful to reduce DNS traffic, but
1296	some (broken) firewalls drop such DNS packets, which is why it is off by
1297	default.
1298
1299	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1300	EDNS0 in its DNS requests.
1301
1302	=item C<PERL_ANYEVENT_MAX_FORKS>
1303
1304	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1305	will create in parallel.
1306
1307	=back
1308		1701
1309	=head1 EXAMPLE PROGRAM	1702	=head1 EXAMPLE PROGRAM
1310		1703
1311	The following program uses an I/O watcher to read data from STDIN, a timer	1704	The following program uses an I/O watcher to read data from STDIN, a timer
1312	to display a message once per second, and a condition variable to quit the	1705	to display a message once per second, and a condition variable to quit the
…		…
1506	watcher.	1899	watcher.
1507		1900
1508	=head3 Results	1901	=head3 Results
1509		1902
1510	name watchers bytes create invoke destroy comment	1903	name watchers bytes create invoke destroy comment
1511	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1904	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1512	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1905	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1513	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1906	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1514	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1907	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1515	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1908	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1516	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1909	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1910	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1911	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1517	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1912	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1518	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1913	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1519	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1914	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1520	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1915	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1521		1916
1522	=head3 Discussion	1917	=head3 Discussion
1523		1918
1524	The benchmark does I<not> measure scalability of the event loop very	1919	The benchmark does I<not> measure scalability of the event loop very
1525	well. For example, a select-based event loop (such as the pure perl one)	1920	well. For example, a select-based event loop (such as the pure perl one)
…		…
1550	performance becomes really bad with lots of file descriptors (and few of	1945	performance becomes really bad with lots of file descriptors (and few of
1551	them active), of course, but this was not subject of this benchmark.	1946	them active), of course, but this was not subject of this benchmark.
1552		1947
1553	The C<Event> module has a relatively high setup and callback invocation	1948	The C<Event> module has a relatively high setup and callback invocation
1554	cost, but overall scores in on the third place.	1949	cost, but overall scores in on the third place.
		1950
		1951	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1952	when using its pure perl backend.
1555		1953
1556	C<Glib>'s memory usage is quite a bit higher, but it features a	1954	C<Glib>'s memory usage is quite a bit higher, but it features a
1557	faster callback invocation and overall ends up in the same class as	1955	faster callback invocation and overall ends up in the same class as
1558	C<Event>. However, Glib scales extremely badly, doubling the number of	1956	C<Event>. However, Glib scales extremely badly, doubling the number of
1559	watchers increases the processing time by more than a factor of four,	1957	watchers increases the processing time by more than a factor of four,
…		…
1637	it to another server. This includes deleting the old timeout and creating	2035	it to another server. This includes deleting the old timeout and creating
1638	a new one that moves the timeout into the future.	2036	a new one that moves the timeout into the future.
1639		2037
1640	=head3 Results	2038	=head3 Results
1641		2039
1642	name sockets create request	2040	name sockets create request
1643	EV 20000 69.01 11.16	2041	EV 20000 69.01 11.16
1644	Perl 20000 73.32 35.87	2042	Perl 20000 73.32 35.87
		2043	IOAsync 20000 157.00 98.14 epoll
		2044	IOAsync 20000 159.31 616.06 poll
1645	Event 20000 212.62 257.32	2045	Event 20000 212.62 257.32
1646	Glib 20000 651.16 1896.30	2046	Glib 20000 651.16 1896.30
1647	POE 20000 349.67 12317.24 uses POE::Loop::Event	2047	POE 20000 349.67 12317.24 uses POE::Loop::Event
1648		2048
1649	=head3 Discussion	2049	=head3 Discussion
1650		2050
1651	This benchmark I<does> measure scalability and overall performance of the	2051	This benchmark I<does> measure scalability and overall performance of the
1652	particular event loop.	2052	particular event loop.
…		…
1654	EV is again fastest. Since it is using epoll on my system, the setup time	2054	EV is again fastest. Since it is using epoll on my system, the setup time
1655	is relatively high, though.	2055	is relatively high, though.
1656		2056
1657	Perl surprisingly comes second. It is much faster than the C-based event	2057	Perl surprisingly comes second. It is much faster than the C-based event
1658	loops Event and Glib.	2058	loops Event and Glib.
		2059
		2060	IO::Async performs very well when using its epoll backend, and still quite
		2061	good compared to Glib when using its pure perl backend.
1659		2062
1660	Event suffers from high setup time as well (look at its code and you will	2063	Event suffers from high setup time as well (look at its code and you will
1661	understand why). Callback invocation also has a high overhead compared to	2064	understand why). Callback invocation also has a high overhead compared to
1662	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2065	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1663	uses select or poll in basically all documented configurations.	2066	uses select or poll in basically all documented configurations.
…		…
1726	=item * C-based event loops perform very well with small number of	2129	=item * C-based event loops perform very well with small number of
1727	watchers, as the management overhead dominates.	2130	watchers, as the management overhead dominates.
1728		2131
1729	=back	2132	=back
1730		2133
		2134	=head2 THE IO::Lambda BENCHMARK
		2135
		2136	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2137	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2138	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2139	shouldn't come as a surprise to anybody). As such, the benchmark is
		2140	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2141	very optimal. But how would AnyEvent compare when used without the extra
		2142	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2143
		2144	The benchmark itself creates an echo-server, and then, for 500 times,
		2145	connects to the echo server, sends a line, waits for the reply, and then
		2146	creates the next connection. This is a rather bad benchmark, as it doesn't
		2147	test the efficiency of the framework or much non-blocking I/O, but it is a
		2148	benchmark nevertheless.
		2149
		2150	name runtime
		2151	Lambda/select 0.330 sec
		2152	+ optimized 0.122 sec
		2153	Lambda/AnyEvent 0.327 sec
		2154	+ optimized 0.138 sec
		2155	Raw sockets/select 0.077 sec
		2156	POE/select, components 0.662 sec
		2157	POE/select, raw sockets 0.226 sec
		2158	POE/select, optimized 0.404 sec
		2159
		2160	AnyEvent/select/nb 0.085 sec
		2161	AnyEvent/EV/nb 0.068 sec
		2162	+state machine 0.134 sec
		2163
		2164	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2165	benchmarks actually make blocking connects and use 100% blocking I/O,
		2166	defeating the purpose of an event-based solution. All of the newly
		2167	written AnyEvent benchmarks use 100% non-blocking connects (using
		2168	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2169	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2170	generally require a lot more bookkeeping and event handling than blocking
		2171	connects (which involve a single syscall only).
		2172
		2173	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2174	offers similar expressive power as POE and IO::Lambda, using conventional
		2175	Perl syntax. This means that both the echo server and the client are 100%
		2176	non-blocking, further placing it at a disadvantage.
		2177
		2178	As you can see, the AnyEvent + EV combination even beats the
		2179	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2180	backend easily beats IO::Lambda and POE.
		2181
		2182	And even the 100% non-blocking version written using the high-level (and
		2183	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2184	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2185	in a non-blocking way.
		2186
		2187	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2188	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2189	part of the IO::lambda distribution and were used without any changes.
		2190
		2191
		2192	=head1 SIGNALS
		2193
		2194	AnyEvent currently installs handlers for these signals:
		2195
		2196	=over 4
		2197
		2198	=item SIGCHLD
		2199
		2200	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2201	emulation for event loops that do not support them natively. Also, some
		2202	event loops install a similar handler.
		2203
		2204	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2205	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2206
		2207	=item SIGPIPE
		2208
		2209	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2210	when AnyEvent gets loaded.
		2211
		2212	The rationale for this is that AnyEvent users usually do not really depend
		2213	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2214	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2215	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2216	some random socket.
		2217
		2218	The rationale for installing a no-op handler as opposed to ignoring it is
		2219	that this way, the handler will be restored to defaults on exec.
		2220
		2221	Feel free to install your own handler, or reset it to defaults.
		2222
		2223	=back
		2224
		2225	=cut
		2226
		2227	undef $SIG{CHLD}
		2228	if $SIG{CHLD} eq 'IGNORE';
		2229
		2230	$SIG{PIPE} = sub { }
		2231	unless defined $SIG{PIPE};
		2232
		2233	=head1 RECOMMENDED/OPTIONAL MODULES
		2234
		2235	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2236	it's built-in modules) are required to use it.
		2237
		2238	That does not mean that AnyEvent won't take advantage of some additional
		2239	modules if they are installed.
		2240
		2241	This section epxlains which additional modules will be used, and how they
		2242	affect AnyEvent's operetion.
		2243
		2244	=over 4
		2245
		2246	=item L<Async::Interrupt>
		2247
		2248	This slightly arcane module is used to implement fast signal handling: To
		2249	my knowledge, there is no way to do completely race-free and quick
		2250	signal handling in pure perl. To ensure that signals still get
		2251	delivered, AnyEvent will start an interval timer to wake up perl (and
		2252	catch the signals) with soemd elay (default is 10 seconds, look for
		2253	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2254
		2255	If this module is available, then it will be used to implement signal
		2256	catching, which means that signals will not be delayed, and the event loop
		2257	will not be interrupted regularly, which is more efficient (And good for
		2258	battery life on laptops).
		2259
		2260	This affects not just the pure-perl event loop, but also other event loops
		2261	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2262
		2263	=item L<EV>
		2264
		2265	This module isn't really "optional", as it is simply one of the backend
		2266	event loops that AnyEvent can use. However, it is simply the best event
		2267	loop available in terms of features, speed and stability: It supports
		2268	the AnyEvent API optimally, implements all the watcher types in XS, does
		2269	automatic timer adjustments even when no monotonic clock is available,
		2270	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2271	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2272	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2273
		2274	=item L<Guard>
		2275
		2276	The guard module, when used, will be used to implement
		2277	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2278	lot less memory), but otherwise doesn't affect guard operation much. It is
		2279	purely used for performance.
		2280
		2281	=item L<JSON> and L<JSON::XS>
		2282
		2283	This module is required when you want to read or write JSON data via
		2284	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2285	advantage of the ulta-high-speed L<JSON::XS> module when it is installed.
		2286
		2287	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2288	installed.
		2289
		2290	=item L<Net::SSLeay>
		2291
		2292	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2293	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2294	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2295
		2296	=item L<Time::HiRes>
		2297
		2298	This module is part of perl since release 5.008. It will be used when the
		2299	chosen event library does not come with a timing source on it's own. The
		2300	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2301	try to use a monotonic clock for timing stability.
		2302
		2303	=back
		2304
1731		2305
1732	=head1 FORK	2306	=head1 FORK
1733		2307
1734	Most event libraries are not fork-safe. The ones who are usually are	2308	Most event libraries are not fork-safe. The ones who are usually are
1735	because they rely on inefficient but fork-safe C<select> or C<poll>	2309	because they rely on inefficient but fork-safe C<select> or C<poll>
1736	calls. Only L<EV> is fully fork-aware.	2310	calls. Only L<EV> is fully fork-aware.
1737		2311
1738	If you have to fork, you must either do so I<before> creating your first	2312	If you have to fork, you must either do so I<before> creating your first
1739	watcher OR you must not use AnyEvent at all in the child.	2313	watcher OR you must not use AnyEvent at all in the child OR you must do
		2314	something completely out of the scope of AnyEvent.
1740		2315
1741		2316
1742	=head1 SECURITY CONSIDERATIONS	2317	=head1 SECURITY CONSIDERATIONS
1743		2318
1744	AnyEvent can be forced to load any event model via	2319	AnyEvent can be forced to load any event model via
…		…
1756	use AnyEvent;	2331	use AnyEvent;
1757		2332
1758	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2333	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1759	be used to probe what backend is used and gain other information (which is	2334	be used to probe what backend is used and gain other information (which is
1760	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2335	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1761	$ENV{PERL_ANYEGENT_STRICT}.	2336	$ENV{PERL_ANYEVENT_STRICT}.
		2337
		2338	Note that AnyEvent will remove I<all> environment variables starting with
		2339	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2340	enabled.
1762		2341
1763		2342
1764	=head1 BUGS	2343	=head1 BUGS
1765		2344
1766	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2345	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1767	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2346	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1768	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2347	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1769	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2348	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1770	pronounced).	2349	pronounced).
1771		2350
1772		2351
1773	=head1 SEE ALSO	2352	=head1 SEE ALSO
1774		2353
…		…
1778	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2357	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1779		2358
1780	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2359	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1781	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2360	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1782	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2361	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1783	L<AnyEvent::Impl::POE>.	2362	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1784		2363
1785	Non-blocking file handles, sockets, TCP clients and	2364	Non-blocking file handles, sockets, TCP clients and
1786	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2365	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1787		2366
1788	Asynchronous DNS: L<AnyEvent::DNS>.	2367	Asynchronous DNS: L<AnyEvent::DNS>.
1789		2368
1790	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2369	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2370	L<Coro::Event>,
1791		2371
1792	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2372	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2373	L<AnyEvent::HTTP>.
1793		2374
1794		2375
1795	=head1 AUTHOR	2376	=head1 AUTHOR
1796		2377
1797	Marc Lehmann <schmorp@schmorp.de>	2378	Marc Lehmann <schmorp@schmorp.de>

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