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Revision 1.175 by root, Sun Jul 27 08:43:32 2008 UTC vs.
Revision 1.246 by root, Sat Jul 18 15:51:52 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
12		14
		15	# one-shot or repeating timers
13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
15		18
16	print AnyEvent->now; # prints current event loop time	19	print AnyEvent->now; # prints current event loop time
17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
18		21
		22	# POSIX signal
19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });	23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
20		24
		25	# child process exit
21	my $w = AnyEvent->child (pid => $pid, cb => sub {	26	my $w = AnyEvent->child (pid => $pid, cb => sub {
22	my ($pid, $status) = @_;	27	my ($pid, $status) = @_;
23	...	28	...
24	});	29	});
		30
		31	# called when event loop idle (if applicable)
		32	my $w = AnyEvent->idle (cb => sub { ... });
25		33
26	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
27	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
28	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
29	# use a condvar in callback mode:	37	# use a condvar in callback mode:
…		…
137	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
138	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
139	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
140	is in control).	148	is in control).
141		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> 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 = 4.23;	1058	our $VERSION = 4.85;
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	use Time::HiRes ();	1231	sub _time {
		1232	# probe for availability of Time::HiRes
		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;
		1235	*_time = \&Time::HiRes::time;
		1236	# if (eval "use POSIX (); (POSIX::times())...
		1237	} else {
		1238	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1239	*_time = sub { time }; # epic fail
		1240	}
1022		1241
1023	sub time { Time::HiRes::time }	1242	&_time
1024	sub now { Time::HiRes::time }	1243	}
		1244
		1245	sub time { _time }
		1246	sub now { _time }
		1247	sub now_update { }
1025		1248
1026	# default implementation for ->condvar	1249	# default implementation for ->condvar
1027		1250
1028	sub condvar {	1251	sub condvar {
1029	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1252	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1030	}	1253	}
1031		1254
1032	# default implementation for ->signal	1255	# default implementation for ->signal
1033		1256
1034	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);
1035		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
		1275	# install a dumym wakeupw atcher to reduce signal catching latency
		1276	sub _sig_add() {
		1277	unless ($SIG_COUNT++) {
		1278	# try to align timer on a full-second boundary, if possible
		1279	my $NOW = AnyEvent->now;
		1280
		1281	$SIG_TW = AnyEvent->timer (
		1282	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1283	interval => $MAX_SIGNAL_LATENCY,
		1284	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1285	);
		1286	}
		1287	}
		1288
		1289	sub _sig_del {
		1290	undef $SIG_TW
		1291	unless --$SIG_COUNT;
		1292	}
		1293
1036	sub signal {	1294	sub _signal {
1037	my (undef, %arg) = @_;	1295	my (undef, %arg) = @_;
1038		1296
1039	my $signal = uc $arg{signal}	1297	my $signal = uc $arg{signal}
1040	or Carp::croak "required option 'signal' is missing";	1298	or Carp::croak "required option 'signal' is missing";
1041		1299
1042	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1300	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1301
		1302	if ($HAVE_ASYNC_INTERRUPT) {
		1303	# async::interrupt
		1304
		1305	$SIG_ASY{$signal} ||= do {
		1306	my $asy = new Async::Interrupt
		1307	cb => sub { undef $SIG_EV{$signal} },
		1308	signal => $signal,
		1309	pipe => [$SIGPIPE_R->filenos],
		1310	;
		1311	$asy->pipe_autodrain (0);
		1312
		1313	$asy
		1314	};
		1315
		1316	} else {
		1317	# pure perl
		1318
1043	$SIG{$signal} ||= sub {	1319	$SIG{$signal} ||= sub {
1044	$_->() for values %{ $SIG_CB{$signal} || {} };	1320	local $!;
		1321	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1322	undef $SIG_EV{$signal};
		1323	};
		1324
		1325	# can't do signal processing without introducing races in pure perl,
		1326	# so limit the signal latency.
		1327	_sig_add;
1045	};	1328	}
1046		1329
1047	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1330	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1048	}	1331	}
1049		1332
		1333	sub signal {
		1334	# probe for availability of Async::Interrupt
		1335	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1336	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1337
		1338	$HAVE_ASYNC_INTERRUPT = 1;
		1339	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1340	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1341
		1342	} else {
		1343	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1344
		1345	require Fcntl;
		1346
		1347	if (AnyEvent::WIN32) {
		1348	require AnyEvent::Util;
		1349
		1350	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1351	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1352	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1353	} else {
		1354	pipe $SIGPIPE_R, $SIGPIPE_W;
		1355	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1356	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1357
		1358	# not strictly required, as $^F is normally 2, but let's make sure...
		1359	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1360	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1361	}
		1362
		1363	$SIGPIPE_R
		1364	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1365
		1366	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1367	}
		1368
		1369	*signal = \&_signal;
		1370	&signal
		1371	}
		1372
1050	sub AnyEvent::Base::Signal::DESTROY {	1373	sub AnyEvent::Base::signal::DESTROY {
1051	my ($signal, $cb) = @{$_[0]};	1374	my ($signal, $cb) = @{$_[0]};
1052		1375
		1376	_sig_del;
		1377
1053	delete $SIG_CB{$signal}{$cb};	1378	delete $SIG_CB{$signal}{$cb};
1054		1379
		1380	$HAVE_ASYNC_INTERRUPT
		1381	? delete $SIG_ASY{$signal}
		1382	: # delete doesn't work with older perls - they then
		1383	# print weird messages, or just unconditionally exit
		1384	# instead of getting the default action.
		1385	undef $SIG{$signal}
1055	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1386	unless keys %{ $SIG_CB{$signal} };
1056	}	1387	}
1057		1388
1058	# default implementation for ->child	1389	# default implementation for ->child
1059		1390
1060	our %PID_CB;	1391	our %PID_CB;
1061	our $CHLD_W;	1392	our $CHLD_W;
1062	our $CHLD_DELAY_W;	1393	our $CHLD_DELAY_W;
1063	our $PID_IDLE;
1064	our $WNOHANG;	1394	our $WNOHANG;
1065		1395
1066	sub _child_wait {	1396	sub _sigchld {
1067	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1397	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1398	$_->($pid, $?)
1068	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1399	for values %{ $PID_CB{$pid} || {} },
1069	(values %{ $PID_CB{0} || {} });	1400	values %{ $PID_CB{0} || {} };
1070	}	1401	}
1071
1072	undef $PID_IDLE;
1073	}
1074
1075	sub _sigchld {
1076	# make sure we deliver these changes "synchronous" with the event loop.
1077	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1078	undef $CHLD_DELAY_W;
1079	&_child_wait;
1080	});
1081	}	1402	}
1082		1403
1083	sub child {	1404	sub child {
1084	my (undef, %arg) = @_;	1405	my (undef, %arg) = @_;
1085		1406
1086	defined (my $pid = $arg{pid} + 0)	1407	defined (my $pid = $arg{pid} + 0)
1087	or Carp::croak "required option 'pid' is missing";	1408	or Carp::croak "required option 'pid' is missing";
1088		1409
1089	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1410	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1090		1411
1091	unless ($WNOHANG) {	1412	# WNOHANG is almost cetrainly 1 everywhere
		1413	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1414	? 1
1092	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1415	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1093	}
1094		1416
1095	unless ($CHLD_W) {	1417	unless ($CHLD_W) {
1096	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1418	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1097	# child could be a zombie already, so make at least one round	1419	# child could be a zombie already, so make at least one round
1098	&_sigchld;	1420	&_sigchld;
1099	}	1421	}
1100		1422
1101	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1423	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1102	}	1424	}
1103		1425
1104	sub AnyEvent::Base::Child::DESTROY {	1426	sub AnyEvent::Base::child::DESTROY {
1105	my ($pid, $cb) = @{$_[0]};	1427	my ($pid, $cb) = @{$_[0]};
1106		1428
1107	delete $PID_CB{$pid}{$cb};	1429	delete $PID_CB{$pid}{$cb};
1108	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1430	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1109		1431
1110	undef $CHLD_W unless keys %PID_CB;	1432	undef $CHLD_W unless keys %PID_CB;
1111	}	1433	}
1112		1434
		1435	# idle emulation is done by simply using a timer, regardless
		1436	# of whether the process is idle or not, and not letting
		1437	# the callback use more than 50% of the time.
		1438	sub idle {
		1439	my (undef, %arg) = @_;
		1440
		1441	my ($cb, $w, $rcb) = $arg{cb};
		1442
		1443	$rcb = sub {
		1444	if ($cb) {
		1445	$w = _time;
		1446	&$cb;
		1447	$w = _time - $w;
		1448
		1449	# never use more then 50% of the time for the idle watcher,
		1450	# within some limits
		1451	$w = 0.0001 if $w < 0.0001;
		1452	$w = 5 if $w > 5;
		1453
		1454	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1455	} else {
		1456	# clean up...
		1457	undef $w;
		1458	undef $rcb;
		1459	}
		1460	};
		1461
		1462	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1463
		1464	bless \\$cb, "AnyEvent::Base::idle"
		1465	}
		1466
		1467	sub AnyEvent::Base::idle::DESTROY {
		1468	undef $${$_[0]};
		1469	}
		1470
1113	package AnyEvent::CondVar;	1471	package AnyEvent::CondVar;
1114		1472
1115	our @ISA = AnyEvent::CondVar::Base::;	1473	our @ISA = AnyEvent::CondVar::Base::;
1116		1474
1117	package AnyEvent::CondVar::Base;	1475	package AnyEvent::CondVar::Base;
1118		1476
1119	use overload	1477	#use overload
1120	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1478	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1121	fallback => 1;	1479	# fallback => 1;
		1480
		1481	# save 300+ kilobytes by dirtily hardcoding overloading
		1482	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1483	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1484	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1485	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1486
		1487	our $WAITING;
1122		1488
1123	sub _send {	1489	sub _send {
1124	# nop	1490	# nop
1125	}	1491	}
1126		1492
…		…
1139	sub ready {	1505	sub ready {
1140	$_[0]{_ae_sent}	1506	$_[0]{_ae_sent}
1141	}	1507	}
1142		1508
1143	sub _wait {	1509	sub _wait {
		1510	$WAITING
		1511	and !$_[0]{_ae_sent}
		1512	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1513
		1514	local $WAITING = 1;
1144	AnyEvent->one_event while !$_[0]{_ae_sent};	1515	AnyEvent->one_event while !$_[0]{_ae_sent};
1145	}	1516	}
1146		1517
1147	sub recv {	1518	sub recv {
1148	$_[0]->_wait;	1519	$_[0]->_wait;
…		…
1167	}	1538	}
1168		1539
1169	# undocumented/compatibility with pre-3.4	1540	# undocumented/compatibility with pre-3.4
1170	*broadcast = \&send;	1541	*broadcast = \&send;
1171	*wait = \&_wait;	1542	*wait = \&_wait;
		1543
		1544	=head1 ERROR AND EXCEPTION HANDLING
		1545
		1546	In general, AnyEvent does not do any error handling - it relies on the
		1547	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1548	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1549	checking of all AnyEvent methods, however, which is highly useful during
		1550	development.
		1551
		1552	As for exception handling (i.e. runtime errors and exceptions thrown while
		1553	executing a callback), this is not only highly event-loop specific, but
		1554	also not in any way wrapped by this module, as this is the job of the main
		1555	program.
		1556
		1557	The pure perl event loop simply re-throws the exception (usually
		1558	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1559	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1560	so on.
		1561
		1562	=head1 ENVIRONMENT VARIABLES
		1563
		1564	The following environment variables are used by this module or its
		1565	submodules.
		1566
		1567	Note that AnyEvent will remove I<all> environment variables starting with
		1568	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1569	enabled.
		1570
		1571	=over 4
		1572
		1573	=item C<PERL_ANYEVENT_VERBOSE>
		1574
		1575	By default, AnyEvent will be completely silent except in fatal
		1576	conditions. You can set this environment variable to make AnyEvent more
		1577	talkative.
		1578
		1579	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1580	conditions, such as not being able to load the event model specified by
		1581	C<PERL_ANYEVENT_MODEL>.
		1582
		1583	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1584	model it chooses.
		1585
		1586	When set to C<8> or higher, then AnyEvent will report extra information on
		1587	which optional modules it loads and how it implements certain features.
		1588
		1589	=item C<PERL_ANYEVENT_STRICT>
		1590
		1591	AnyEvent does not do much argument checking by default, as thorough
		1592	argument checking is very costly. Setting this variable to a true value
		1593	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1594	check the arguments passed to most method calls. If it finds any problems,
		1595	it will croak.
		1596
		1597	In other words, enables "strict" mode.
		1598
		1599	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1600	>>, it is definitely recommended to keep it off in production. Keeping
		1601	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1602	can be very useful, however.
		1603
		1604	=item C<PERL_ANYEVENT_MODEL>
		1605
		1606	This can be used to specify the event model to be used by AnyEvent, before
		1607	auto detection and -probing kicks in. It must be a string consisting
		1608	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1609	and the resulting module name is loaded and if the load was successful,
		1610	used as event model. If it fails to load AnyEvent will proceed with
		1611	auto detection and -probing.
		1612
		1613	This functionality might change in future versions.
		1614
		1615	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1616	could start your program like this:
		1617
		1618	PERL_ANYEVENT_MODEL=Perl perl ...
		1619
		1620	=item C<PERL_ANYEVENT_PROTOCOLS>
		1621
		1622	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1623	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1624	of auto probing).
		1625
		1626	Must be set to a comma-separated list of protocols or address families,
		1627	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1628	used, and preference will be given to protocols mentioned earlier in the
		1629	list.
		1630
		1631	This variable can effectively be used for denial-of-service attacks
		1632	against local programs (e.g. when setuid), although the impact is likely
		1633	small, as the program has to handle conenction and other failures anyways.
		1634
		1635	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1636	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1637	- only support IPv4, never try to resolve or contact IPv6
		1638	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1639	IPv6, but prefer IPv6 over IPv4.
		1640
		1641	=item C<PERL_ANYEVENT_EDNS0>
		1642
		1643	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1644	for DNS. This extension is generally useful to reduce DNS traffic, but
		1645	some (broken) firewalls drop such DNS packets, which is why it is off by
		1646	default.
		1647
		1648	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1649	EDNS0 in its DNS requests.
		1650
		1651	=item C<PERL_ANYEVENT_MAX_FORKS>
		1652
		1653	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1654	will create in parallel.
		1655
		1656	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1657
		1658	The default value for the C<max_outstanding> parameter for the default DNS
		1659	resolver - this is the maximum number of parallel DNS requests that are
		1660	sent to the DNS server.
		1661
		1662	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1663
		1664	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1665	configuration) in the default resolver. When set to the empty string, no
		1666	default config will be used.
		1667
		1668	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1669
		1670	When neither C<ca_file> nor C<ca_path> was specified during
		1671	L<AnyEvent::TLS> context creation, and either of these environment
		1672	variables exist, they will be used to specify CA certificate locations
		1673	instead of a system-dependent default.
		1674
		1675	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1676
		1677	When these are set to C<1>, then the respective modules are not
		1678	loaded. Mostly good for testing AnyEvent itself.
		1679
		1680	=back
1172		1681
1173	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1682	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1174		1683
1175	This is an advanced topic that you do not normally need to use AnyEvent in	1684	This is an advanced topic that you do not normally need to use AnyEvent in
1176	a module. This section is only of use to event loop authors who want to	1685	a module. This section is only of use to event loop authors who want to
…		…
1210		1719
1211	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1720	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1212	condition variables: code blocking while waiting for a condition will	1721	condition variables: code blocking while waiting for a condition will
1213	C<die>. This still works with most modules/usages, and blocking calls must	1722	C<die>. This still works with most modules/usages, and blocking calls must
1214	not be done in an interactive application, so it makes sense.	1723	not be done in an interactive application, so it makes sense.
1215
1216	=head1 ENVIRONMENT VARIABLES
1217
1218	The following environment variables are used by this module:
1219
1220	=over 4
1221
1222	=item C<PERL_ANYEVENT_VERBOSE>
1223
1224	By default, AnyEvent will be completely silent except in fatal
1225	conditions. You can set this environment variable to make AnyEvent more
1226	talkative.
1227
1228	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1229	conditions, such as not being able to load the event model specified by
1230	C<PERL_ANYEVENT_MODEL>.
1231
1232	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1233	model it chooses.
1234
1235	=item C<PERL_ANYEVENT_STRICT>
1236
1237	AnyEvent does not do much argument checking by default, as thorough
1238	argument checking is very costly. Setting this variable to a true value
1239	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1240	check the arguments passed to most method calls. If it finds any problems
1241	it will croak.
1242
1243	In other words, enables "strict" mode.
1244
1245	Unlike C<use strict> it is definitely recommended ot keep it off in
1246	production.
1247
1248	=item C<PERL_ANYEVENT_MODEL>
1249
1250	This can be used to specify the event model to be used by AnyEvent, before
1251	auto detection and -probing kicks in. It must be a string consisting
1252	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1253	and the resulting module name is loaded and if the load was successful,
1254	used as event model. If it fails to load AnyEvent will proceed with
1255	auto detection and -probing.
1256
1257	This functionality might change in future versions.
1258
1259	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1260	could start your program like this:
1261
1262	PERL_ANYEVENT_MODEL=Perl perl ...
1263
1264	=item C<PERL_ANYEVENT_PROTOCOLS>
1265
1266	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1267	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1268	of auto probing).
1269
1270	Must be set to a comma-separated list of protocols or address families,
1271	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1272	used, and preference will be given to protocols mentioned earlier in the
1273	list.
1274
1275	This variable can effectively be used for denial-of-service attacks
1276	against local programs (e.g. when setuid), although the impact is likely
1277	small, as the program has to handle connection errors already-
1278
1279	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1280	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1281	- only support IPv4, never try to resolve or contact IPv6
1282	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1283	IPv6, but prefer IPv6 over IPv4.
1284
1285	=item C<PERL_ANYEVENT_EDNS0>
1286
1287	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1288	for DNS. This extension is generally useful to reduce DNS traffic, but
1289	some (broken) firewalls drop such DNS packets, which is why it is off by
1290	default.
1291
1292	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1293	EDNS0 in its DNS requests.
1294
1295	=item C<PERL_ANYEVENT_MAX_FORKS>
1296
1297	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1298	will create in parallel.
1299
1300	=back
1301		1724
1302	=head1 EXAMPLE PROGRAM	1725	=head1 EXAMPLE PROGRAM
1303		1726
1304	The following program uses an I/O watcher to read data from STDIN, a timer	1727	The following program uses an I/O watcher to read data from STDIN, a timer
1305	to display a message once per second, and a condition variable to quit the	1728	to display a message once per second, and a condition variable to quit the
…		…
1499	watcher.	1922	watcher.
1500		1923
1501	=head3 Results	1924	=head3 Results
1502		1925
1503	name watchers bytes create invoke destroy comment	1926	name watchers bytes create invoke destroy comment
1504	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1927	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1505	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1928	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1506	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1929	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1507	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1930	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1508	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1931	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1509	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1932	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1933	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1934	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1510	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1935	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1511	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1936	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1512	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1937	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1513	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1938	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1514		1939
1515	=head3 Discussion	1940	=head3 Discussion
1516		1941
1517	The benchmark does I<not> measure scalability of the event loop very	1942	The benchmark does I<not> measure scalability of the event loop very
1518	well. For example, a select-based event loop (such as the pure perl one)	1943	well. For example, a select-based event loop (such as the pure perl one)
…		…
1543	performance becomes really bad with lots of file descriptors (and few of	1968	performance becomes really bad with lots of file descriptors (and few of
1544	them active), of course, but this was not subject of this benchmark.	1969	them active), of course, but this was not subject of this benchmark.
1545		1970
1546	The C<Event> module has a relatively high setup and callback invocation	1971	The C<Event> module has a relatively high setup and callback invocation
1547	cost, but overall scores in on the third place.	1972	cost, but overall scores in on the third place.
		1973
		1974	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1975	when using its pure perl backend.
1548		1976
1549	C<Glib>'s memory usage is quite a bit higher, but it features a	1977	C<Glib>'s memory usage is quite a bit higher, but it features a
1550	faster callback invocation and overall ends up in the same class as	1978	faster callback invocation and overall ends up in the same class as
1551	C<Event>. However, Glib scales extremely badly, doubling the number of	1979	C<Event>. However, Glib scales extremely badly, doubling the number of
1552	watchers increases the processing time by more than a factor of four,	1980	watchers increases the processing time by more than a factor of four,
…		…
1630	it to another server. This includes deleting the old timeout and creating	2058	it to another server. This includes deleting the old timeout and creating
1631	a new one that moves the timeout into the future.	2059	a new one that moves the timeout into the future.
1632		2060
1633	=head3 Results	2061	=head3 Results
1634		2062
1635	name sockets create request	2063	name sockets create request
1636	EV 20000 69.01 11.16	2064	EV 20000 69.01 11.16
1637	Perl 20000 73.32 35.87	2065	Perl 20000 73.32 35.87
		2066	IOAsync 20000 157.00 98.14 epoll
		2067	IOAsync 20000 159.31 616.06 poll
1638	Event 20000 212.62 257.32	2068	Event 20000 212.62 257.32
1639	Glib 20000 651.16 1896.30	2069	Glib 20000 651.16 1896.30
1640	POE 20000 349.67 12317.24 uses POE::Loop::Event	2070	POE 20000 349.67 12317.24 uses POE::Loop::Event
1641		2071
1642	=head3 Discussion	2072	=head3 Discussion
1643		2073
1644	This benchmark I<does> measure scalability and overall performance of the	2074	This benchmark I<does> measure scalability and overall performance of the
1645	particular event loop.	2075	particular event loop.
…		…
1647	EV is again fastest. Since it is using epoll on my system, the setup time	2077	EV is again fastest. Since it is using epoll on my system, the setup time
1648	is relatively high, though.	2078	is relatively high, though.
1649		2079
1650	Perl surprisingly comes second. It is much faster than the C-based event	2080	Perl surprisingly comes second. It is much faster than the C-based event
1651	loops Event and Glib.	2081	loops Event and Glib.
		2082
		2083	IO::Async performs very well when using its epoll backend, and still quite
		2084	good compared to Glib when using its pure perl backend.
1652		2085
1653	Event suffers from high setup time as well (look at its code and you will	2086	Event suffers from high setup time as well (look at its code and you will
1654	understand why). Callback invocation also has a high overhead compared to	2087	understand why). Callback invocation also has a high overhead compared to
1655	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2088	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1656	uses select or poll in basically all documented configurations.	2089	uses select or poll in basically all documented configurations.
…		…
1719	=item * C-based event loops perform very well with small number of	2152	=item * C-based event loops perform very well with small number of
1720	watchers, as the management overhead dominates.	2153	watchers, as the management overhead dominates.
1721		2154
1722	=back	2155	=back
1723		2156
		2157	=head2 THE IO::Lambda BENCHMARK
		2158
		2159	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2160	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2161	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2162	shouldn't come as a surprise to anybody). As such, the benchmark is
		2163	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2164	very optimal. But how would AnyEvent compare when used without the extra
		2165	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2166
		2167	The benchmark itself creates an echo-server, and then, for 500 times,
		2168	connects to the echo server, sends a line, waits for the reply, and then
		2169	creates the next connection. This is a rather bad benchmark, as it doesn't
		2170	test the efficiency of the framework or much non-blocking I/O, but it is a
		2171	benchmark nevertheless.
		2172
		2173	name runtime
		2174	Lambda/select 0.330 sec
		2175	+ optimized 0.122 sec
		2176	Lambda/AnyEvent 0.327 sec
		2177	+ optimized 0.138 sec
		2178	Raw sockets/select 0.077 sec
		2179	POE/select, components 0.662 sec
		2180	POE/select, raw sockets 0.226 sec
		2181	POE/select, optimized 0.404 sec
		2182
		2183	AnyEvent/select/nb 0.085 sec
		2184	AnyEvent/EV/nb 0.068 sec
		2185	+state machine 0.134 sec
		2186
		2187	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2188	benchmarks actually make blocking connects and use 100% blocking I/O,
		2189	defeating the purpose of an event-based solution. All of the newly
		2190	written AnyEvent benchmarks use 100% non-blocking connects (using
		2191	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2192	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2193	generally require a lot more bookkeeping and event handling than blocking
		2194	connects (which involve a single syscall only).
		2195
		2196	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2197	offers similar expressive power as POE and IO::Lambda, using conventional
		2198	Perl syntax. This means that both the echo server and the client are 100%
		2199	non-blocking, further placing it at a disadvantage.
		2200
		2201	As you can see, the AnyEvent + EV combination even beats the
		2202	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2203	backend easily beats IO::Lambda and POE.
		2204
		2205	And even the 100% non-blocking version written using the high-level (and
		2206	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2207	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2208	in a non-blocking way.
		2209
		2210	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2211	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2212	part of the IO::lambda distribution and were used without any changes.
		2213
		2214
		2215	=head1 SIGNALS
		2216
		2217	AnyEvent currently installs handlers for these signals:
		2218
		2219	=over 4
		2220
		2221	=item SIGCHLD
		2222
		2223	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2224	emulation for event loops that do not support them natively. Also, some
		2225	event loops install a similar handler.
		2226
		2227	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2228	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2229
		2230	=item SIGPIPE
		2231
		2232	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2233	when AnyEvent gets loaded.
		2234
		2235	The rationale for this is that AnyEvent users usually do not really depend
		2236	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2237	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2238	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2239	some random socket.
		2240
		2241	The rationale for installing a no-op handler as opposed to ignoring it is
		2242	that this way, the handler will be restored to defaults on exec.
		2243
		2244	Feel free to install your own handler, or reset it to defaults.
		2245
		2246	=back
		2247
		2248	=cut
		2249
		2250	undef $SIG{CHLD}
		2251	if $SIG{CHLD} eq 'IGNORE';
		2252
		2253	$SIG{PIPE} = sub { }
		2254	unless defined $SIG{PIPE};
		2255
		2256	=head1 RECOMMENDED/OPTIONAL MODULES
		2257
		2258	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2259	it's built-in modules) are required to use it.
		2260
		2261	That does not mean that AnyEvent won't take advantage of some additional
		2262	modules if they are installed.
		2263
		2264	This section epxlains which additional modules will be used, and how they
		2265	affect AnyEvent's operetion.
		2266
		2267	=over 4
		2268
		2269	=item L<Async::Interrupt>
		2270
		2271	This slightly arcane module is used to implement fast signal handling: To
		2272	my knowledge, there is no way to do completely race-free and quick
		2273	signal handling in pure perl. To ensure that signals still get
		2274	delivered, AnyEvent will start an interval timer to wake up perl (and
		2275	catch the signals) with soemd elay (default is 10 seconds, look for
		2276	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2277
		2278	If this module is available, then it will be used to implement signal
		2279	catching, which means that signals will not be delayed, and the event loop
		2280	will not be interrupted regularly, which is more efficient (And good for
		2281	battery life on laptops).
		2282
		2283	This affects not just the pure-perl event loop, but also other event loops
		2284	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2285
		2286	=item L<EV>
		2287
		2288	This module isn't really "optional", as it is simply one of the backend
		2289	event loops that AnyEvent can use. However, it is simply the best event
		2290	loop available in terms of features, speed and stability: It supports
		2291	the AnyEvent API optimally, implements all the watcher types in XS, does
		2292	automatic timer adjustments even when no monotonic clock is available,
		2293	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2294	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2295	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2296
		2297	=item L<Guard>
		2298
		2299	The guard module, when used, will be used to implement
		2300	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2301	lot less memory), but otherwise doesn't affect guard operation much. It is
		2302	purely used for performance.
		2303
		2304	=item L<JSON> and L<JSON::XS>
		2305
		2306	This module is required when you want to read or write JSON data via
		2307	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2308	advantage of the ulta-high-speed L<JSON::XS> module when it is installed.
		2309
		2310	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2311	installed.
		2312
		2313	=item L<Net::SSLeay>
		2314
		2315	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2316	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2317	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2318
		2319	=item L<Time::HiRes>
		2320
		2321	This module is part of perl since release 5.008. It will be used when the
		2322	chosen event library does not come with a timing source on it's own. The
		2323	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2324	try to use a monotonic clock for timing stability.
		2325
		2326	=back
		2327
1724		2328
1725	=head1 FORK	2329	=head1 FORK
1726		2330
1727	Most event libraries are not fork-safe. The ones who are usually are	2331	Most event libraries are not fork-safe. The ones who are usually are
1728	because they rely on inefficient but fork-safe C<select> or C<poll>	2332	because they rely on inefficient but fork-safe C<select> or C<poll>
1729	calls. Only L<EV> is fully fork-aware.	2333	calls. Only L<EV> is fully fork-aware.
1730		2334
1731	If you have to fork, you must either do so I<before> creating your first	2335	If you have to fork, you must either do so I<before> creating your first
1732	watcher OR you must not use AnyEvent at all in the child.	2336	watcher OR you must not use AnyEvent at all in the child OR you must do
		2337	something completely out of the scope of AnyEvent.
1733		2338
1734		2339
1735	=head1 SECURITY CONSIDERATIONS	2340	=head1 SECURITY CONSIDERATIONS
1736		2341
1737	AnyEvent can be forced to load any event model via	2342	AnyEvent can be forced to load any event model via
…		…
1749	use AnyEvent;	2354	use AnyEvent;
1750		2355
1751	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2356	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1752	be used to probe what backend is used and gain other information (which is	2357	be used to probe what backend is used and gain other information (which is
1753	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2358	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1754	$ENV{PERL_ANYEGENT_STRICT}.	2359	$ENV{PERL_ANYEVENT_STRICT}.
		2360
		2361	Note that AnyEvent will remove I<all> environment variables starting with
		2362	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2363	enabled.
1755		2364
1756		2365
1757	=head1 BUGS	2366	=head1 BUGS
1758		2367
1759	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2368	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1760	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2369	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1761	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2370	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1762	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2371	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1763	pronounced).	2372	pronounced).
1764		2373
1765		2374
1766	=head1 SEE ALSO	2375	=head1 SEE ALSO
1767		2376
…		…
1771	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2380	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1772		2381
1773	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2382	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1774	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2383	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1775	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2384	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1776	L<AnyEvent::Impl::POE>.	2385	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1777		2386
1778	Non-blocking file handles, sockets, TCP clients and	2387	Non-blocking file handles, sockets, TCP clients and
1779	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2388	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1780		2389
1781	Asynchronous DNS: L<AnyEvent::DNS>.	2390	Asynchronous DNS: L<AnyEvent::DNS>.
1782		2391
1783	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2392	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2393	L<Coro::Event>,
1784		2394
1785	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2395	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2396	L<AnyEvent::HTTP>.
1786		2397
1787		2398
1788	=head1 AUTHOR	2399	=head1 AUTHOR
1789		2400
1790	Marc Lehmann <schmorp@schmorp.de>	2401	Marc Lehmann <schmorp@schmorp.de>

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