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Revision 1.250 by root, Mon Jul 20 07:12:38 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - events independent of event loop implementation
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 $condvar gets ->send
29	# use a condvar in callback mode:	37	# use a condvar in callback mode:
…		…
32	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
33		41
34	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
35	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
36	L<AnyEvent::Intro> manpage.	44	L<AnyEvent::Intro> manpage.
		45
		46	=head1 SUPPORT
		47
		48	There is a mailinglist for discussing all things AnyEvent, and an IRC
		49	channel, too.
		50
		51	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		52	Respository>, at L<http://anyevent.schmorp.de>, for more info.
37		53
38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
39		55
40	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
41	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
…		…
137	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
138	creating a watcher it will immediately "watch" for events and invoke the	154	creating a watcher it will immediately "watch" for events and invoke the
139	callback when the event occurs (of course, only when the event model	155	callback when the event occurs (of course, only when the event model
140	is in control).	156	is in control).
141		157
		158	Note that B<callbacks must not permanently change global variables>
		159	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		160	callbacks must not C<die> >>. The former is good programming practise in
		161	Perl and the latter stems from the fact that exception handling differs
		162	widely between event loops.
		163
142	To disable the watcher you have to destroy it (e.g. by setting the	164	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	165	variable you store it in to C<undef> or otherwise deleting all references
144	to it).	166	to it).
145		167
146	All watchers are created by calling a method on the C<AnyEvent> class.	168	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
162	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
163		185
164	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	186	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
165	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
166		188
167	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	189	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>	190	for events (AnyEvent might or might not keep a reference to this file
		191	handle). Note that only file handles pointing to things for which
		192	non-blocking operation makes sense are allowed. This includes sockets,
		193	most character devices, pipes, fifos and so on, but not for example files
		194	or block devices.
		195
169	must be a string that is either C<r> or C<w>, which creates a watcher	196	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	197	watcher waiting for "r"eadable or "w"ritable events, respectively.
		198
171	callback to invoke each time the file handle becomes ready.	199	C<cb> is the callback to invoke each time the file handle becomes ready.
172		200
173	Although the callback might get passed parameters, their value and	201	Although the callback might get passed parameters, their value and
174	presence is undefined and you cannot rely on them. Portable AnyEvent	202	presence is undefined and you cannot rely on them. Portable AnyEvent
175	callbacks cannot use arguments passed to I/O watcher callbacks.	203	callbacks cannot use arguments passed to I/O watcher callbacks.
176		204
…		…
308	In either case, if you care (and in most cases, you don't), then you	336	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	337	can get whatever behaviour you want with any event loop, by taking the
310	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	338	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
311	account.	339	account.
312		340
		341	=item AnyEvent->now_update
		342
		343	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		344	the current time for each loop iteration (see the discussion of L<<
		345	AnyEvent->now >>, above).
		346
		347	When a callback runs for a long time (or when the process sleeps), then
		348	this "current" time will differ substantially from the real time, which
		349	might affect timers and time-outs.
		350
		351	When this is the case, you can call this method, which will update the
		352	event loop's idea of "current time".
		353
		354	Note that updating the time I<might> cause some events to be handled.
		355
313	=back	356	=back
314		357
315	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
316		359
317	You can watch for signals using a signal watcher, C<signal> is the signal	360	You can watch for signals using a signal watcher, C<signal> is the signal
…		…
326	invocation, and callback invocation will be synchronous. Synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
327	that it might take a while until the signal gets handled by the process,	370	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.	371	but it is guaranteed not to interrupt any other callbacks.
329		372
330	The main advantage of using these watchers is that you can share a signal	373	The main advantage of using these watchers is that you can share a signal
331	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
332		376
333	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
334	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
335		380
336	Example: exit on SIGINT	381	Example: exit on SIGINT
337		382
338	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
339		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		392	seconds). This variable can be changed only before the first signal
		393	watcher is created, and should be left alone otherwise. Higher values
		394	will cause fewer spurious wake-ups, which is better for power and CPU
		395	saving. All these problems can be avoided by installing the optional
		396	L<Async::Interrupt> module. This will not work with inherently broken
		397	event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
		398	currently, as POE does it's own workaround with one-second latency). With
		399	those, you just have to suffer the delays.
		400
340	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
341		402
342	You can also watch on a child process exit and catch its exit status.	403	You can also watch on a child process exit and catch its exit status.
343		404
344	The child process is specified by the C<pid> argument (if set to C<0>, it	405	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	406	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	407	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	408	any trace events (stopped/continued).
348	and exit status (as returned by waitpid), so unlike other watcher types,	409
349	you I<can> rely on child watcher callback arguments.	410	The callback will be called with the pid and exit status (as returned by
		411	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		412	callback arguments.
		413
		414	This watcher type works by installing a signal handler for C<SIGCHLD>,
		415	and since it cannot be shared, nothing else should use SIGCHLD or reap
		416	random child processes (waiting for specific child processes, e.g. inside
		417	C<system>, is just fine).
350		418
351	There is a slight catch to child watchers, however: you usually start them	419	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	420	I<after> the child process was created, and this means the process could
353	have exited already (and no SIGCHLD will be sent anymore).	421	have exited already (and no SIGCHLD will be sent anymore).
354		422
355	Not all event models handle this correctly (POE doesn't), but even for	423	Not all event models handle this correctly (neither POE nor IO::Async do,
		424	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	425	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).	426	the process exits (i.e. before you fork in the first place). AnyEvent's
		427	pure perl event loop handles all cases correctly regardless of when you
		428	start the watcher.
358		429
359	This means you cannot create a child watcher as the very first thing in an	430	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	431	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>).	432	watcher before you C<fork> the child (alternatively, you can call
		433	C<AnyEvent::detect>).
		434
		435	As most event loops do not support waiting for child events, they will be
		436	emulated by AnyEvent in most cases, in which the latency and race problems
		437	mentioned in the description of signal watchers apply.
362		438
363	Example: fork a process and wait for it	439	Example: fork a process and wait for it
364		440
365	my $done = AnyEvent->condvar;	441	my $done = AnyEvent->condvar;
366		442
…		…
376	);	452	);
377		453
378	# do something else, then wait for process exit	454	# do something else, then wait for process exit
379	$done->recv;	455	$done->recv;
380		456
		457	=head2 IDLE WATCHERS
		458
		459	Sometimes there is a need to do something, but it is not so important
		460	to do it instantly, but only when there is nothing better to do. This
		461	"nothing better to do" is usually defined to be "no other events need
		462	attention by the event loop".
		463
		464	Idle watchers ideally get invoked when the event loop has nothing
		465	better to do, just before it would block the process to wait for new
		466	events. Instead of blocking, the idle watcher is invoked.
		467
		468	Most event loops unfortunately do not really support idle watchers (only
		469	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		470	will simply call the callback "from time to time".
		471
		472	Example: read lines from STDIN, but only process them when the
		473	program is otherwise idle:
		474
		475	my @lines; # read data
		476	my $idle_w;
		477	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		478	push @lines, scalar <STDIN>;
		479
		480	# start an idle watcher, if not already done
		481	$idle_w ||= AnyEvent->idle (cb => sub {
		482	# handle only one line, when there are lines left
		483	if (my $line = shift @lines) {
		484	print "handled when idle: $line";
		485	} else {
		486	# otherwise disable the idle watcher again
		487	undef $idle_w;
		488	}
		489	});
		490	});
		491
381	=head2 CONDITION VARIABLES	492	=head2 CONDITION VARIABLES
382		493
383	If you are familiar with some event loops you will know that all of them	494	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	495	require you to run some blocking "loop", "run" or similar function that
385	will actively watch for new events and call your callbacks.	496	will actively watch for new events and call your callbacks.
386		497
387	AnyEvent is different, it expects somebody else to run the event loop and	498	AnyEvent is slightly different: it expects somebody else to run the event
388	will only block when necessary (usually when told by the user).	499	loop and will only block when necessary (usually when told by the user).
389		500
390	The instrument to do that is called a "condition variable", so called	501	The instrument to do that is called a "condition variable", so called
391	because they represent a condition that must become true.	502	because they represent a condition that must become true.
392		503
		504	Now is probably a good time to look at the examples further below.
		505
393	Condition variables can be created by calling the C<< AnyEvent->condvar	506	Condition variables can be created by calling the C<< AnyEvent->condvar
394
395	>> method, usually without arguments. The only argument pair allowed is	507	>> method, usually without arguments. The only argument pair allowed is
396
397	C<cb>, which specifies a callback to be called when the condition variable	508	C<cb>, which specifies a callback to be called when the condition variable
398	becomes true, with the condition variable as the first argument (but not	509	becomes true, with the condition variable as the first argument (but not
399	the results).	510	the results).
400		511
401	After creation, the condition variable is "false" until it becomes "true"	512	After creation, the condition variable is "false" until it becomes "true"
…		…
406	Condition variables are similar to callbacks, except that you can	517	Condition variables are similar to callbacks, except that you can
407	optionally wait for them. They can also be called merge points - points	518	optionally wait for them. They can also be called merge points - points
408	in time where multiple outstanding events have been processed. And yet	519	in time where multiple outstanding events have been processed. And yet
409	another way to call them is transactions - each condition variable can be	520	another way to call them is transactions - each condition variable can be
410	used to represent a transaction, which finishes at some point and delivers	521	used to represent a transaction, which finishes at some point and delivers
411	a result.	522	a result. And yet some people know them as "futures" - a promise to
		523	compute/deliver something that you can wait for.
412		524
413	Condition variables are very useful to signal that something has finished,	525	Condition variables are very useful to signal that something has finished,
414	for example, if you write a module that does asynchronous http requests,	526	for example, if you write a module that does asynchronous http requests,
415	then a condition variable would be the ideal candidate to signal the	527	then a condition variable would be the ideal candidate to signal the
416	availability of results. The user can either act when the callback is	528	availability of results. The user can either act when the callback is
…		…
450	after => 1,	562	after => 1,
451	cb => sub { $result_ready->send },	563	cb => sub { $result_ready->send },
452	);	564	);
453		565
454	# this "blocks" (while handling events) till the callback	566	# this "blocks" (while handling events) till the callback
455	# calls send	567	# calls -<send
456	$result_ready->recv;	568	$result_ready->recv;
457		569
458	Example: wait for a timer, but take advantage of the fact that	570	Example: wait for a timer, but take advantage of the fact that condition
459	condition variables are also code references.	571	variables are also callable directly.
460		572
461	my $done = AnyEvent->condvar;	573	my $done = AnyEvent->condvar;
462	my $delay = AnyEvent->timer (after => 5, cb => $done);	574	my $delay = AnyEvent->timer (after => 5, cb => $done);
463	$done->recv;	575	$done->recv;
464		576
…		…
470		582
471	...	583	...
472		584
473	my @info = $couchdb->info->recv;	585	my @info = $couchdb->info->recv;
474		586
475	And this is how you would just ste a callback to be called whenever the	587	And this is how you would just set a callback to be called whenever the
476	results are available:	588	results are available:
477		589
478	$couchdb->info->cb (sub {	590	$couchdb->info->cb (sub {
479	my @info = $_[0]->recv;	591	my @info = $_[0]->recv;
480	});	592	});
…		…
498	immediately from within send.	610	immediately from within send.
499		611
500	Any arguments passed to the C<send> call will be returned by all	612	Any arguments passed to the C<send> call will be returned by all
501	future C<< ->recv >> calls.	613	future C<< ->recv >> calls.
502		614
503	Condition variables are overloaded so one can call them directly	615	Condition variables are overloaded so one can call them directly (as if
504	(as a code reference). Calling them directly is the same as calling	616	they were a code reference). Calling them directly is the same as calling
505	C<send>. Note, however, that many C-based event loops do not handle	617	C<send>.
506	overloading, so as tempting as it may be, passing a condition variable
507	instead of a callback does not work. Both the pure perl and EV loops
508	support overloading, however, as well as all functions that use perl to
509	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
510	example).
511		618
512	=item $cv->croak ($error)	619	=item $cv->croak ($error)
513		620
514	Similar to send, but causes all call's to C<< ->recv >> to invoke	621	Similar to send, but causes all call's to C<< ->recv >> to invoke
515	C<Carp::croak> with the given error message/object/scalar.	622	C<Carp::croak> with the given error message/object/scalar.
516		623
517	This can be used to signal any errors to the condition variable	624	This can be used to signal any errors to the condition variable
518	user/consumer.	625	user/consumer. Doing it this way instead of calling C<croak> directly
		626	delays the error detetcion, but has the overwhelmign advantage that it
		627	diagnoses the error at the place where the result is expected, and not
		628	deep in some event clalback without connection to the actual code causing
		629	the problem.
519		630
520	=item $cv->begin ([group callback])	631	=item $cv->begin ([group callback])
521		632
522	=item $cv->end	633	=item $cv->end
523
524	These two methods are EXPERIMENTAL and MIGHT CHANGE.
525		634
526	These two methods can be used to combine many transactions/events into	635	These two methods can be used to combine many transactions/events into
527	one. For example, a function that pings many hosts in parallel might want	636	one. For example, a function that pings many hosts in parallel might want
528	to use a condition variable for the whole process.	637	to use a condition variable for the whole process.
529		638
…		…
531	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	640	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
532	>>, the (last) callback passed to C<begin> will be executed. That callback	641	>>, the (last) callback passed to C<begin> will be executed. That callback
533	is I<supposed> to call C<< ->send >>, but that is not required. If no	642	is I<supposed> to call C<< ->send >>, but that is not required. If no
534	callback was set, C<send> will be called without any arguments.	643	callback was set, C<send> will be called without any arguments.
535		644
536	Let's clarify this with the ping example:	645	You can think of C<< $cv->send >> giving you an OR condition (one call
		646	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		647	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		648
		649	Let's start with a simple example: you have two I/O watchers (for example,
		650	STDOUT and STDERR for a program), and you want to wait for both streams to
		651	close before activating a condvar:
		652
		653	my $cv = AnyEvent->condvar;
		654
		655	$cv->begin; # first watcher
		656	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		657	defined sysread $fh1, my $buf, 4096
		658	or $cv->end;
		659	});
		660
		661	$cv->begin; # second watcher
		662	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		663	defined sysread $fh2, my $buf, 4096
		664	or $cv->end;
		665	});
		666
		667	$cv->recv;
		668
		669	This works because for every event source (EOF on file handle), there is
		670	one call to C<begin>, so the condvar waits for all calls to C<end> before
		671	sending.
		672
		673	The ping example mentioned above is slightly more complicated, as the
		674	there are results to be passwd back, and the number of tasks that are
		675	begung can potentially be zero:
537		676
538	my $cv = AnyEvent->condvar;	677	my $cv = AnyEvent->condvar;
539		678
540	my %result;	679	my %result;
541	$cv->begin (sub { $cv->send (\%result) });	680	$cv->begin (sub { $cv->send (\%result) });
…		…
561	loop, which serves two important purposes: first, it sets the callback	700	loop, which serves two important purposes: first, it sets the callback
562	to be called once the counter reaches C<0>, and second, it ensures that	701	to be called once the counter reaches C<0>, and second, it ensures that
563	C<send> is called even when C<no> hosts are being pinged (the loop	702	C<send> is called even when C<no> hosts are being pinged (the loop
564	doesn't execute once).	703	doesn't execute once).
565		704
566	This is the general pattern when you "fan out" into multiple subrequests:	705	This is the general pattern when you "fan out" into multiple (but
567	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	706	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
568	is called at least once, and then, for each subrequest you start, call	707	the callback and ensure C<end> is called at least once, and then, for each
569	C<begin> and for each subrequest you finish, call C<end>.	708	subrequest you start, call C<begin> and for each subrequest you finish,
		709	call C<end>.
570		710
571	=back	711	=back
572		712
573	=head3 METHODS FOR CONSUMERS	713	=head3 METHODS FOR CONSUMERS
574		714
…		…
590	function will call C<croak>.	730	function will call C<croak>.
591		731
592	In list context, all parameters passed to C<send> will be returned,	732	In list context, all parameters passed to C<send> will be returned,
593	in scalar context only the first one will be returned.	733	in scalar context only the first one will be returned.
594		734
		735	Note that doing a blocking wait in a callback is not supported by any
		736	event loop, that is, recursive invocation of a blocking C<< ->recv
		737	>> is not allowed, and the C<recv> call will C<croak> if such a
		738	condition is detected. This condition can be slightly loosened by using
		739	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		740	any thread that doesn't run the event loop itself.
		741
595	Not all event models support a blocking wait - some die in that case	742	Not all event models support a blocking wait - some die in that case
596	(programs might want to do that to stay interactive), so I<if you are	743	(programs might want to do that to stay interactive), so I<if you are
597	using this from a module, never require a blocking wait>, but let the	744	using this from a module, never require a blocking wait>. Instead, let the
598	caller decide whether the call will block or not (for example, by coupling	745	caller decide whether the call will block or not (for example, by coupling
599	condition variables with some kind of request results and supporting	746	condition variables with some kind of request results and supporting
600	callbacks so the caller knows that getting the result will not block,	747	callbacks so the caller knows that getting the result will not block,
601	while still supporting blocking waits if the caller so desires).	748	while still supporting blocking waits if the caller so desires).
602		749
603	Another reason I<never> to C<< ->recv >> in a module is that you cannot
604	sensibly have two C<< ->recv >>'s in parallel, as that would require
605	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
606	can supply.
607
608	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
609	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
610	versions and also integrates coroutines into AnyEvent, making blocking
611	C<< ->recv >> calls perfectly safe as long as they are done from another
612	coroutine (one that doesn't run the event loop).
613
614	You can ensure that C<< -recv >> never blocks by setting a callback and	750	You can ensure that C<< -recv >> never blocks by setting a callback and
615	only calling C<< ->recv >> from within that callback (or at a later	751	only calling C<< ->recv >> from within that callback (or at a later
616	time). This will work even when the event loop does not support blocking	752	time). This will work even when the event loop does not support blocking
617	waits otherwise.	753	waits otherwise.
618		754
…		…
631	variable itself. Calling C<recv> inside the callback or at any later time	767	variable itself. Calling C<recv> inside the callback or at any later time
632	is guaranteed not to block.	768	is guaranteed not to block.
633		769
634	=back	770	=back
635		771
		772	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		773
		774	The available backend classes are (every class has its own manpage):
		775
		776	=over 4
		777
		778	=item Backends that are autoprobed when no other event loop can be found.
		779
		780	EV is the preferred backend when no other event loop seems to be in
		781	use. If EV is not installed, then AnyEvent will try Event, and, failing
		782	that, will fall back to its own pure-perl implementation, which is
		783	available everywhere as it comes with AnyEvent itself.
		784
		785	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		786	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		787	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		788
		789	=item Backends that are transparently being picked up when they are used.
		790
		791	These will be used when they are currently loaded when the first watcher
		792	is created, in which case it is assumed that the application is using
		793	them. This means that AnyEvent will automatically pick the right backend
		794	when the main program loads an event module before anything starts to
		795	create watchers. Nothing special needs to be done by the main program.
		796
		797	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		798	AnyEvent::Impl::Tk based on Tk, very broken.
		799	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		800	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		801
		802	=item Backends with special needs.
		803
		804	Qt requires the Qt::Application to be instantiated first, but will
		805	otherwise be picked up automatically. As long as the main program
		806	instantiates the application before any AnyEvent watchers are created,
		807	everything should just work.
		808
		809	AnyEvent::Impl::Qt based on Qt.
		810
		811	Support for IO::Async can only be partial, as it is too broken and
		812	architecturally limited to even support the AnyEvent API. It also
		813	is the only event loop that needs the loop to be set explicitly, so
		814	it can only be used by a main program knowing about AnyEvent. See
		815	L<AnyEvent::Impl::Async> for the gory details.
		816
		817	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		818
		819	=item Event loops that are indirectly supported via other backends.
		820
		821	Some event loops can be supported via other modules:
		822
		823	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		824
		825	B<WxWidgets> has no support for watching file handles. However, you can
		826	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		827	polls 20 times per second, which was considered to be too horrible to even
		828	consider for AnyEvent.
		829
		830	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		831	backend, so it can be supported through POE.
		832
		833	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		834	load L<POE> when detecting them, in the hope that POE will pick them up,
		835	in which case everything will be automatic.
		836
		837	=back
		838
636	=head1 GLOBAL VARIABLES AND FUNCTIONS	839	=head1 GLOBAL VARIABLES AND FUNCTIONS
637		840
		841	These are not normally required to use AnyEvent, but can be useful to
		842	write AnyEvent extension modules.
		843
638	=over 4	844	=over 4
639		845
640	=item $AnyEvent::MODEL	846	=item $AnyEvent::MODEL
641		847
642	Contains C<undef> until the first watcher is being created. Then it	848	Contains C<undef> until the first watcher is being created, before the
		849	backend has been autodetected.
		850
643	contains the event model that is being used, which is the name of the	851	Afterwards it contains the event model that is being used, which is the
644	Perl class implementing the model. This class is usually one of the	852	name of the Perl class implementing the model. This class is usually one
645	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	853	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
646	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	854	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
647		855	will be C<urxvt::anyevent>).
648	The known classes so far are:
649
650	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
651	AnyEvent::Impl::Event based on Event, second best choice.
652	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
653	AnyEvent::Impl::Glib based on Glib, third-best choice.
654	AnyEvent::Impl::Tk based on Tk, very bad choice.
655	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
656	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
657	AnyEvent::Impl::POE based on POE, not generic enough for full support.
658
659	There is no support for WxWidgets, as WxWidgets has no support for
660	watching file handles. However, you can use WxWidgets through the
661	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
662	second, which was considered to be too horrible to even consider for
663	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
664	it's adaptor.
665
666	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
667	autodetecting them.
668		856
669	=item AnyEvent::detect	857	=item AnyEvent::detect
670		858
671	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	859	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
672	if necessary. You should only call this function right before you would	860	if necessary. You should only call this function right before you would
673	have created an AnyEvent watcher anyway, that is, as late as possible at	861	have created an AnyEvent watcher anyway, that is, as late as possible at
674	runtime.	862	runtime, and not e.g. while initialising of your module.
		863
		864	If you need to do some initialisation before AnyEvent watchers are
		865	created, use C<post_detect>.
675		866
676	=item $guard = AnyEvent::post_detect { BLOCK }	867	=item $guard = AnyEvent::post_detect { BLOCK }
677		868
678	Arranges for the code block to be executed as soon as the event model is	869	Arranges for the code block to be executed as soon as the event model is
679	autodetected (or immediately if this has already happened).	870	autodetected (or immediately if this has already happened).
		871
		872	The block will be executed I<after> the actual backend has been detected
		873	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		874	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		875	other initialisations - see the sources of L<AnyEvent::Strict> or
		876	L<AnyEvent::AIO> to see how this is used.
		877
		878	The most common usage is to create some global watchers, without forcing
		879	event module detection too early, for example, L<AnyEvent::AIO> creates
		880	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		881	avoid autodetecting the event module at load time.
680		882
681	If called in scalar or list context, then it creates and returns an object	883	If called in scalar or list context, then it creates and returns an object
682	that automatically removes the callback again when it is destroyed. See	884	that automatically removes the callback again when it is destroyed. See
683	L<Coro::BDB> for a case where this is useful.	885	L<Coro::BDB> for a case where this is useful.
684		886
…		…
687	If there are any code references in this array (you can C<push> to it	889	If there are any code references in this array (you can C<push> to it
688	before or after loading AnyEvent), then they will called directly after	890	before or after loading AnyEvent), then they will called directly after
689	the event loop has been chosen.	891	the event loop has been chosen.
690		892
691	You should check C<$AnyEvent::MODEL> before adding to this array, though:	893	You should check C<$AnyEvent::MODEL> before adding to this array, though:
692	if it contains a true value then the event loop has already been detected,	894	if it is defined then the event loop has already been detected, and the
693	and the array will be ignored.	895	array will be ignored.
694		896
695	Best use C<AnyEvent::post_detect { BLOCK }> instead.	897	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		898	it,as it takes care of these details.
		899
		900	This variable is mainly useful for modules that can do something useful
		901	when AnyEvent is used and thus want to know when it is initialised, but do
		902	not need to even load it by default. This array provides the means to hook
		903	into AnyEvent passively, without loading it.
696		904
697	=back	905	=back
698		906
699	=head1 WHAT TO DO IN A MODULE	907	=head1 WHAT TO DO IN A MODULE
700		908
…		…
755		963
756		964
757	=head1 OTHER MODULES	965	=head1 OTHER MODULES
758		966
759	The following is a non-exhaustive list of additional modules that use	967	The following is a non-exhaustive list of additional modules that use
760	AnyEvent and can therefore be mixed easily with other AnyEvent modules	968	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
761	in the same program. Some of the modules come with AnyEvent, some are	969	modules and other event loops in the same program. Some of the modules
762	available via CPAN.	970	come with AnyEvent, most are available via CPAN.
763		971
764	=over 4	972	=over 4
765		973
766	=item L<AnyEvent::Util>	974	=item L<AnyEvent::Util>
767		975
…		…
776		984
777	=item L<AnyEvent::Handle>	985	=item L<AnyEvent::Handle>
778		986
779	Provide read and write buffers, manages watchers for reads and writes,	987	Provide read and write buffers, manages watchers for reads and writes,
780	supports raw and formatted I/O, I/O queued and fully transparent and	988	supports raw and formatted I/O, I/O queued and fully transparent and
781	non-blocking SSL/TLS.	989	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
782		990
783	=item L<AnyEvent::DNS>	991	=item L<AnyEvent::DNS>
784		992
785	Provides rich asynchronous DNS resolver capabilities.	993	Provides rich asynchronous DNS resolver capabilities.
786		994
…		…
814		1022
815	=item L<AnyEvent::GPSD>	1023	=item L<AnyEvent::GPSD>
816		1024
817	A non-blocking interface to gpsd, a daemon delivering GPS information.	1025	A non-blocking interface to gpsd, a daemon delivering GPS information.
818		1026
		1027	=item L<AnyEvent::IRC>
		1028
		1029	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1030
		1031	=item L<AnyEvent::XMPP>
		1032
		1033	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1034	Net::XMPP2>.
		1035
819	=item L<AnyEvent::IGS>	1036	=item L<AnyEvent::IGS>
820		1037
821	A non-blocking interface to the Internet Go Server protocol (used by	1038	A non-blocking interface to the Internet Go Server protocol (used by
822	L<App::IGS>).	1039	L<App::IGS>).
823		1040
824	=item L<Net::IRC3>
825
826	AnyEvent based IRC client module family.
827
828	=item L<Net::XMPP2>
829
830	AnyEvent based XMPP (Jabber protocol) module family.
831
832	=item L<Net::FCP>	1041	=item L<Net::FCP>
833		1042
834	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1043	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
835	of AnyEvent.	1044	of AnyEvent.
836		1045
…		…
840		1049
841	=item L<Coro>	1050	=item L<Coro>
842		1051
843	Has special support for AnyEvent via L<Coro::AnyEvent>.	1052	Has special support for AnyEvent via L<Coro::AnyEvent>.
844		1053
845	=item L<IO::Lambda>
846
847	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
848
849	=back	1054	=back
850		1055
851	=cut	1056	=cut
852		1057
853	package AnyEvent;	1058	package AnyEvent;
854		1059
		1060	# basically a tuned-down version of common::sense
		1061	sub common_sense {
855	no warnings;	1062	# no warnings
856	use strict;	1063	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1064	# use strict vars subs
		1065	$^H |= 0x00000600;
		1066	}
857		1067
		1068	BEGIN { AnyEvent::common_sense }
		1069
858	use Carp;	1070	use Carp ();
859		1071
860	our $VERSION = 4.22;	1072	our $VERSION = 4.85;
861	our $MODEL;	1073	our $MODEL;
862		1074
863	our $AUTOLOAD;	1075	our $AUTOLOAD;
864	our @ISA;	1076	our @ISA;
865		1077
866	our @REGISTRY;	1078	our @REGISTRY;
867		1079
868	our $WIN32;	1080	our $WIN32;
869		1081
		1082	our $VERBOSE;
		1083
870	BEGIN {	1084	BEGIN {
871	my $win32 = ! ! ($^O =~ /mswin32/i);	1085	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
872	eval "sub WIN32(){ $win32 }";	1086	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
873	}
874		1087
		1088	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1089	if ${^TAINT};
		1090
875	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1091	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1092
		1093	}
		1094
		1095	our $MAX_SIGNAL_LATENCY = 10;
876		1096
877	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1097	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
878		1098
879	{	1099	{
880	my $idx;	1100	my $idx;
…		…
888	[Event:: => AnyEvent::Impl::Event::],	1108	[Event:: => AnyEvent::Impl::Event::],
889	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1109	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
890	# everything below here will not be autoprobed	1110	# everything below here will not be autoprobed
891	# as the pureperl backend should work everywhere	1111	# as the pureperl backend should work everywhere
892	# and is usually faster	1112	# and is usually faster
893	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
894	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1113	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
895	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1114	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1115	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
896	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1116	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
897	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1117	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
898	[Wx:: => AnyEvent::Impl::POE::],	1118	[Wx:: => AnyEvent::Impl::POE::],
899	[Prima:: => AnyEvent::Impl::POE::],	1119	[Prima:: => AnyEvent::Impl::POE::],
		1120	# IO::Async is just too broken - we would need workarounds for its
		1121	# byzantine signal and broken child handling, among others.
		1122	# IO::Async is rather hard to detect, as it doesn't have any
		1123	# obvious default class.
		1124	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1125	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1126	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
900	);	1127	);
901		1128
902	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1129	our %method = map +($_ => 1),
		1130	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
903		1131
904	our @post_detect;	1132	our @post_detect;
905		1133
906	sub post_detect(&) {	1134	sub post_detect(&) {
907	my ($cb) = @_;	1135	my ($cb) = @_;
…		…
912	1	1140	1
913	} else {	1141	} else {
914	push @post_detect, $cb;	1142	push @post_detect, $cb;
915		1143
916	defined wantarray	1144	defined wantarray
917	? bless \$cb, "AnyEvent::Util::PostDetect"	1145	? bless \$cb, "AnyEvent::Util::postdetect"
918	: ()	1146	: ()
919	}	1147	}
920	}	1148	}
921		1149
922	sub AnyEvent::Util::PostDetect::DESTROY {	1150	sub AnyEvent::Util::postdetect::DESTROY {
923	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1151	@post_detect = grep $_ != ${$_[0]}, @post_detect;
924	}	1152	}
925		1153
926	sub detect() {	1154	sub detect() {
927	unless ($MODEL) {	1155	unless ($MODEL) {
928	no strict 'refs';
929	local $SIG{__DIE__};	1156	local $SIG{__DIE__};
930		1157
931	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1158	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
932	my $model = "AnyEvent::Impl::$1";	1159	my $model = "AnyEvent::Impl::$1";
933	if (eval "require $model") {	1160	if (eval "require $model") {
934	$MODEL = $model;	1161	$MODEL = $model;
935	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1162	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
936	} else {	1163	} else {
937	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1164	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
938	}	1165	}
939	}	1166	}
940		1167
941	# check for already loaded models	1168	# check for already loaded models
942	unless ($MODEL) {	1169	unless ($MODEL) {
943	for (@REGISTRY, @models) {	1170	for (@REGISTRY, @models) {
944	my ($package, $model) = @$_;	1171	my ($package, $model) = @$_;
945	if (${"$package\::VERSION"} > 0) {	1172	if (${"$package\::VERSION"} > 0) {
946	if (eval "require $model") {	1173	if (eval "require $model") {
947	$MODEL = $model;	1174	$MODEL = $model;
948	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1175	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
949	last;	1176	last;
950	}	1177	}
951	}	1178	}
952	}	1179	}
953		1180
…		…
958	my ($package, $model) = @$_;	1185	my ($package, $model) = @$_;
959	if (eval "require $package"	1186	if (eval "require $package"
960	and ${"$package\::VERSION"} > 0	1187	and ${"$package\::VERSION"} > 0
961	and eval "require $model") {	1188	and eval "require $model") {
962	$MODEL = $model;	1189	$MODEL = $model;
963	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1190	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
964	last;	1191	last;
965	}	1192	}
966	}	1193	}
967		1194
968	$MODEL	1195	$MODEL
969	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1196	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
970	}	1197	}
971	}	1198	}
972		1199
973	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1200	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
974		1201
…		…
984		1211
985	sub AUTOLOAD {	1212	sub AUTOLOAD {
986	(my $func = $AUTOLOAD) =~ s/.*://;	1213	(my $func = $AUTOLOAD) =~ s/.*://;
987		1214
988	$method{$func}	1215	$method{$func}
989	or croak "$func: not a valid method for AnyEvent objects";	1216	or Carp::croak "$func: not a valid method for AnyEvent objects";
990		1217
991	detect unless $MODEL;	1218	detect unless $MODEL;
992		1219
993	my $class = shift;	1220	my $class = shift;
994	$class->$func (@_);	1221	$class->$func (@_);
995	}	1222	}
996		1223
997	# utility function to dup a filehandle. this is used by many backends	1224	# utility function to dup a filehandle. this is used by many backends
998	# to support binding more than one watcher per filehandle (they usually	1225	# to support binding more than one watcher per filehandle (they usually
999	# allow only one watcher per fd, so we dup it to get a different one).	1226	# allow only one watcher per fd, so we dup it to get a different one).
1000	sub _dupfh($$$$) {	1227	sub _dupfh($$;$$) {
1001	my ($poll, $fh, $r, $w) = @_;	1228	my ($poll, $fh, $r, $w) = @_;
1002		1229
1003	require Fcntl;
1004
1005	# cygwin requires the fh mode to be matching, unix doesn't	1230	# cygwin requires the fh mode to be matching, unix doesn't
1006	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1231	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1007	: $poll eq "w" ? ($w, ">")
1008	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1009		1232
1010	open my $fh2, "$mode&" . fileno $fh	1233	open my $fh2, $mode, $fh
1011	or die "cannot dup() filehandle: $!";	1234	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1012		1235
1013	# we assume CLOEXEC is already set by perl in all important cases	1236	# we assume CLOEXEC is already set by perl in all important cases
1014		1237
1015	($fh2, $rw)	1238	($fh2, $rw)
1016	}	1239	}
1017		1240
1018	package AnyEvent::Base;	1241	package AnyEvent::Base;
1019		1242
1020	# default implementation for now and time	1243	# default implementations for many methods
1021		1244
1022	use Time::HiRes ();	1245	sub _time {
		1246	# probe for availability of Time::HiRes
		1247	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1248	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1249	*_time = \&Time::HiRes::time;
		1250	# if (eval "use POSIX (); (POSIX::times())...
		1251	} else {
		1252	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1253	*_time = sub { time }; # epic fail
		1254	}
1023		1255
1024	sub time { Time::HiRes::time }	1256	&_time
1025	sub now { Time::HiRes::time }	1257	}
		1258
		1259	sub time { _time }
		1260	sub now { _time }
		1261	sub now_update { }
1026		1262
1027	# default implementation for ->condvar	1263	# default implementation for ->condvar
1028		1264
1029	sub condvar {	1265	sub condvar {
1030	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1266	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1031	}	1267	}
1032		1268
1033	# default implementation for ->signal	1269	# default implementation for ->signal
1034		1270
1035	our %SIG_CB;	1271	our $HAVE_ASYNC_INTERRUPT;
		1272	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1273	our (%SIG_ASY, %SIG_ASY_W);
		1274	our ($SIG_COUNT, $SIG_TW);
1036		1275
		1276	sub _signal_exec {
		1277	$HAVE_ASYNC_INTERRUPT
		1278	? $SIGPIPE_R->drain
		1279	: sysread $SIGPIPE_R, my $dummy, 9;
		1280
		1281	while (%SIG_EV) {
		1282	for (keys %SIG_EV) {
		1283	delete $SIG_EV{$_};
		1284	$_->() for values %{ $SIG_CB{$_} || {} };
		1285	}
		1286	}
		1287	}
		1288
		1289	# install a dumym wakeupw atcher to reduce signal catching latency
		1290	sub _sig_add() {
		1291	unless ($SIG_COUNT++) {
		1292	# try to align timer on a full-second boundary, if possible
		1293	my $NOW = AnyEvent->now;
		1294
		1295	$SIG_TW = AnyEvent->timer (
		1296	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1297	interval => $MAX_SIGNAL_LATENCY,
		1298	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1299	);
		1300	}
		1301	}
		1302
		1303	sub _sig_del {
		1304	undef $SIG_TW
		1305	unless --$SIG_COUNT;
		1306	}
		1307
1037	sub signal {	1308	sub _signal {
1038	my (undef, %arg) = @_;	1309	my (undef, %arg) = @_;
1039		1310
1040	my $signal = uc $arg{signal}	1311	my $signal = uc $arg{signal}
1041	or Carp::croak "required option 'signal' is missing";	1312	or Carp::croak "required option 'signal' is missing";
1042		1313
1043	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1314	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1315
		1316	if ($HAVE_ASYNC_INTERRUPT) {
		1317	# async::interrupt
		1318
		1319	$SIG_ASY{$signal} ||= do {
		1320	my $asy = new Async::Interrupt
		1321	cb => sub { undef $SIG_EV{$signal} },
		1322	signal => $signal,
		1323	pipe => [$SIGPIPE_R->filenos],
		1324	;
		1325	$asy->pipe_autodrain (0);
		1326
		1327	$asy
		1328	};
		1329
		1330	} else {
		1331	# pure perl
		1332
1044	$SIG{$signal} ||= sub {	1333	$SIG{$signal} ||= sub {
1045	$_->() for values %{ $SIG_CB{$signal} || {} };	1334	local $!;
		1335	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1336	undef $SIG_EV{$signal};
		1337	};
		1338
		1339	# can't do signal processing without introducing races in pure perl,
		1340	# so limit the signal latency.
		1341	_sig_add;
1046	};	1342	}
1047		1343
1048	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1344	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1049	}	1345	}
1050		1346
		1347	sub signal {
		1348	# probe for availability of Async::Interrupt
		1349	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1350	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1351
		1352	$HAVE_ASYNC_INTERRUPT = 1;
		1353	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1354	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1355
		1356	} else {
		1357	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1358
		1359	require Fcntl;
		1360
		1361	if (AnyEvent::WIN32) {
		1362	require AnyEvent::Util;
		1363
		1364	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1365	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1366	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1367	} else {
		1368	pipe $SIGPIPE_R, $SIGPIPE_W;
		1369	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1370	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1371
		1372	# not strictly required, as $^F is normally 2, but let's make sure...
		1373	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1374	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1375	}
		1376
		1377	$SIGPIPE_R
		1378	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1379
		1380	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1381	}
		1382
		1383	*signal = \&_signal;
		1384	&signal
		1385	}
		1386
1051	sub AnyEvent::Base::Signal::DESTROY {	1387	sub AnyEvent::Base::signal::DESTROY {
1052	my ($signal, $cb) = @{$_[0]};	1388	my ($signal, $cb) = @{$_[0]};
1053		1389
		1390	_sig_del;
		1391
1054	delete $SIG_CB{$signal}{$cb};	1392	delete $SIG_CB{$signal}{$cb};
1055		1393
		1394	$HAVE_ASYNC_INTERRUPT
		1395	? delete $SIG_ASY{$signal}
		1396	: # delete doesn't work with older perls - they then
		1397	# print weird messages, or just unconditionally exit
		1398	# instead of getting the default action.
		1399	undef $SIG{$signal}
1056	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1400	unless keys %{ $SIG_CB{$signal} };
1057	}	1401	}
1058		1402
1059	# default implementation for ->child	1403	# default implementation for ->child
1060		1404
1061	our %PID_CB;	1405	our %PID_CB;
1062	our $CHLD_W;	1406	our $CHLD_W;
1063	our $CHLD_DELAY_W;	1407	our $CHLD_DELAY_W;
1064	our $PID_IDLE;
1065	our $WNOHANG;	1408	our $WNOHANG;
1066		1409
1067	sub _child_wait {	1410	sub _sigchld {
1068	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1411	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1412	$_->($pid, $?)
1069	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1413	for values %{ $PID_CB{$pid} || {} },
1070	(values %{ $PID_CB{0} || {} });	1414	values %{ $PID_CB{0} || {} };
1071	}	1415	}
1072
1073	undef $PID_IDLE;
1074	}
1075
1076	sub _sigchld {
1077	# make sure we deliver these changes "synchronous" with the event loop.
1078	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1079	undef $CHLD_DELAY_W;
1080	&_child_wait;
1081	});
1082	}	1416	}
1083		1417
1084	sub child {	1418	sub child {
1085	my (undef, %arg) = @_;	1419	my (undef, %arg) = @_;
1086		1420
1087	defined (my $pid = $arg{pid} + 0)	1421	defined (my $pid = $arg{pid} + 0)
1088	or Carp::croak "required option 'pid' is missing";	1422	or Carp::croak "required option 'pid' is missing";
1089		1423
1090	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1424	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1091		1425
1092	unless ($WNOHANG) {	1426	# WNOHANG is almost cetrainly 1 everywhere
		1427	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1428	? 1
1093	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1429	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1094	}
1095		1430
1096	unless ($CHLD_W) {	1431	unless ($CHLD_W) {
1097	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1432	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1098	# child could be a zombie already, so make at least one round	1433	# child could be a zombie already, so make at least one round
1099	&_sigchld;	1434	&_sigchld;
1100	}	1435	}
1101		1436
1102	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1437	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1103	}	1438	}
1104		1439
1105	sub AnyEvent::Base::Child::DESTROY {	1440	sub AnyEvent::Base::child::DESTROY {
1106	my ($pid, $cb) = @{$_[0]};	1441	my ($pid, $cb) = @{$_[0]};
1107		1442
1108	delete $PID_CB{$pid}{$cb};	1443	delete $PID_CB{$pid}{$cb};
1109	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1444	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1110		1445
1111	undef $CHLD_W unless keys %PID_CB;	1446	undef $CHLD_W unless keys %PID_CB;
1112	}	1447	}
1113		1448
		1449	# idle emulation is done by simply using a timer, regardless
		1450	# of whether the process is idle or not, and not letting
		1451	# the callback use more than 50% of the time.
		1452	sub idle {
		1453	my (undef, %arg) = @_;
		1454
		1455	my ($cb, $w, $rcb) = $arg{cb};
		1456
		1457	$rcb = sub {
		1458	if ($cb) {
		1459	$w = _time;
		1460	&$cb;
		1461	$w = _time - $w;
		1462
		1463	# never use more then 50% of the time for the idle watcher,
		1464	# within some limits
		1465	$w = 0.0001 if $w < 0.0001;
		1466	$w = 5 if $w > 5;
		1467
		1468	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1469	} else {
		1470	# clean up...
		1471	undef $w;
		1472	undef $rcb;
		1473	}
		1474	};
		1475
		1476	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1477
		1478	bless \\$cb, "AnyEvent::Base::idle"
		1479	}
		1480
		1481	sub AnyEvent::Base::idle::DESTROY {
		1482	undef $${$_[0]};
		1483	}
		1484
1114	package AnyEvent::CondVar;	1485	package AnyEvent::CondVar;
1115		1486
1116	our @ISA = AnyEvent::CondVar::Base::;	1487	our @ISA = AnyEvent::CondVar::Base::;
1117		1488
1118	package AnyEvent::CondVar::Base;	1489	package AnyEvent::CondVar::Base;
1119		1490
1120	use overload	1491	#use overload
1121	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1492	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1122	fallback => 1;	1493	# fallback => 1;
		1494
		1495	# save 300+ kilobytes by dirtily hardcoding overloading
		1496	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1497	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1498	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1499	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1500
		1501	our $WAITING;
1123		1502
1124	sub _send {	1503	sub _send {
1125	# nop	1504	# nop
1126	}	1505	}
1127		1506
…		…
1140	sub ready {	1519	sub ready {
1141	$_[0]{_ae_sent}	1520	$_[0]{_ae_sent}
1142	}	1521	}
1143		1522
1144	sub _wait {	1523	sub _wait {
		1524	$WAITING
		1525	and !$_[0]{_ae_sent}
		1526	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1527
		1528	local $WAITING = 1;
1145	AnyEvent->one_event while !$_[0]{_ae_sent};	1529	AnyEvent->one_event while !$_[0]{_ae_sent};
1146	}	1530	}
1147		1531
1148	sub recv {	1532	sub recv {
1149	$_[0]->_wait;	1533	$_[0]->_wait;
…		…
1168	}	1552	}
1169		1553
1170	# undocumented/compatibility with pre-3.4	1554	# undocumented/compatibility with pre-3.4
1171	*broadcast = \&send;	1555	*broadcast = \&send;
1172	*wait = \&_wait;	1556	*wait = \&_wait;
		1557
		1558	=head1 ERROR AND EXCEPTION HANDLING
		1559
		1560	In general, AnyEvent does not do any error handling - it relies on the
		1561	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1562	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1563	checking of all AnyEvent methods, however, which is highly useful during
		1564	development.
		1565
		1566	As for exception handling (i.e. runtime errors and exceptions thrown while
		1567	executing a callback), this is not only highly event-loop specific, but
		1568	also not in any way wrapped by this module, as this is the job of the main
		1569	program.
		1570
		1571	The pure perl event loop simply re-throws the exception (usually
		1572	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1573	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1574	so on.
		1575
		1576	=head1 ENVIRONMENT VARIABLES
		1577
		1578	The following environment variables are used by this module or its
		1579	submodules.
		1580
		1581	Note that AnyEvent will remove I<all> environment variables starting with
		1582	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1583	enabled.
		1584
		1585	=over 4
		1586
		1587	=item C<PERL_ANYEVENT_VERBOSE>
		1588
		1589	By default, AnyEvent will be completely silent except in fatal
		1590	conditions. You can set this environment variable to make AnyEvent more
		1591	talkative.
		1592
		1593	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1594	conditions, such as not being able to load the event model specified by
		1595	C<PERL_ANYEVENT_MODEL>.
		1596
		1597	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1598	model it chooses.
		1599
		1600	When set to C<8> or higher, then AnyEvent will report extra information on
		1601	which optional modules it loads and how it implements certain features.
		1602
		1603	=item C<PERL_ANYEVENT_STRICT>
		1604
		1605	AnyEvent does not do much argument checking by default, as thorough
		1606	argument checking is very costly. Setting this variable to a true value
		1607	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1608	check the arguments passed to most method calls. If it finds any problems,
		1609	it will croak.
		1610
		1611	In other words, enables "strict" mode.
		1612
		1613	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1614	>>, it is definitely recommended to keep it off in production. Keeping
		1615	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1616	can be very useful, however.
		1617
		1618	=item C<PERL_ANYEVENT_MODEL>
		1619
		1620	This can be used to specify the event model to be used by AnyEvent, before
		1621	auto detection and -probing kicks in. It must be a string consisting
		1622	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1623	and the resulting module name is loaded and if the load was successful,
		1624	used as event model. If it fails to load AnyEvent will proceed with
		1625	auto detection and -probing.
		1626
		1627	This functionality might change in future versions.
		1628
		1629	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1630	could start your program like this:
		1631
		1632	PERL_ANYEVENT_MODEL=Perl perl ...
		1633
		1634	=item C<PERL_ANYEVENT_PROTOCOLS>
		1635
		1636	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1637	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1638	of auto probing).
		1639
		1640	Must be set to a comma-separated list of protocols or address families,
		1641	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1642	used, and preference will be given to protocols mentioned earlier in the
		1643	list.
		1644
		1645	This variable can effectively be used for denial-of-service attacks
		1646	against local programs (e.g. when setuid), although the impact is likely
		1647	small, as the program has to handle conenction and other failures anyways.
		1648
		1649	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1650	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1651	- only support IPv4, never try to resolve or contact IPv6
		1652	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1653	IPv6, but prefer IPv6 over IPv4.
		1654
		1655	=item C<PERL_ANYEVENT_EDNS0>
		1656
		1657	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1658	for DNS. This extension is generally useful to reduce DNS traffic, but
		1659	some (broken) firewalls drop such DNS packets, which is why it is off by
		1660	default.
		1661
		1662	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1663	EDNS0 in its DNS requests.
		1664
		1665	=item C<PERL_ANYEVENT_MAX_FORKS>
		1666
		1667	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1668	will create in parallel.
		1669
		1670	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1671
		1672	The default value for the C<max_outstanding> parameter for the default DNS
		1673	resolver - this is the maximum number of parallel DNS requests that are
		1674	sent to the DNS server.
		1675
		1676	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1677
		1678	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1679	configuration) in the default resolver. When set to the empty string, no
		1680	default config will be used.
		1681
		1682	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1683
		1684	When neither C<ca_file> nor C<ca_path> was specified during
		1685	L<AnyEvent::TLS> context creation, and either of these environment
		1686	variables exist, they will be used to specify CA certificate locations
		1687	instead of a system-dependent default.
		1688
		1689	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1690
		1691	When these are set to C<1>, then the respective modules are not
		1692	loaded. Mostly good for testing AnyEvent itself.
		1693
		1694	=back
1173		1695
1174	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1696	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1175		1697
1176	This is an advanced topic that you do not normally need to use AnyEvent in	1698	This is an advanced topic that you do not normally need to use AnyEvent in
1177	a module. This section is only of use to event loop authors who want to	1699	a module. This section is only of use to event loop authors who want to
…		…
1211		1733
1212	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1734	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1213	condition variables: code blocking while waiting for a condition will	1735	condition variables: code blocking while waiting for a condition will
1214	C<die>. This still works with most modules/usages, and blocking calls must	1736	C<die>. This still works with most modules/usages, and blocking calls must
1215	not be done in an interactive application, so it makes sense.	1737	not be done in an interactive application, so it makes sense.
1216
1217	=head1 ENVIRONMENT VARIABLES
1218
1219	The following environment variables are used by this module:
1220
1221	=over 4
1222
1223	=item C<PERL_ANYEVENT_VERBOSE>
1224
1225	By default, AnyEvent will be completely silent except in fatal
1226	conditions. You can set this environment variable to make AnyEvent more
1227	talkative.
1228
1229	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1230	conditions, such as not being able to load the event model specified by
1231	C<PERL_ANYEVENT_MODEL>.
1232
1233	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1234	model it chooses.
1235
1236	=item C<PERL_ANYEVENT_STRICT>
1237
1238	AnyEvent does not do much argument checking by default, as thorough
1239	argument checking is very costly. Setting this variable to a true value
1240	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1241	check the arguments passed to most method calls. If it finds any problems
1242	it will croak.
1243
1244	In other words, enables "strict" mode.
1245
1246	Unlike C<use strict> it is definitely recommended ot keep it off in
1247	production.
1248
1249	=item C<PERL_ANYEVENT_MODEL>
1250
1251	This can be used to specify the event model to be used by AnyEvent, before
1252	auto detection and -probing kicks in. It must be a string consisting
1253	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1254	and the resulting module name is loaded and if the load was successful,
1255	used as event model. If it fails to load AnyEvent will proceed with
1256	auto detection and -probing.
1257
1258	This functionality might change in future versions.
1259
1260	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1261	could start your program like this:
1262
1263	PERL_ANYEVENT_MODEL=Perl perl ...
1264
1265	=item C<PERL_ANYEVENT_PROTOCOLS>
1266
1267	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1268	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1269	of auto probing).
1270
1271	Must be set to a comma-separated list of protocols or address families,
1272	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1273	used, and preference will be given to protocols mentioned earlier in the
1274	list.
1275
1276	This variable can effectively be used for denial-of-service attacks
1277	against local programs (e.g. when setuid), although the impact is likely
1278	small, as the program has to handle connection errors already-
1279
1280	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1281	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1282	- only support IPv4, never try to resolve or contact IPv6
1283	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1284	IPv6, but prefer IPv6 over IPv4.
1285
1286	=item C<PERL_ANYEVENT_EDNS0>
1287
1288	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1289	for DNS. This extension is generally useful to reduce DNS traffic, but
1290	some (broken) firewalls drop such DNS packets, which is why it is off by
1291	default.
1292
1293	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1294	EDNS0 in its DNS requests.
1295
1296	=item C<PERL_ANYEVENT_MAX_FORKS>
1297
1298	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1299	will create in parallel.
1300
1301	=back
1302		1738
1303	=head1 EXAMPLE PROGRAM	1739	=head1 EXAMPLE PROGRAM
1304		1740
1305	The following program uses an I/O watcher to read data from STDIN, a timer	1741	The following program uses an I/O watcher to read data from STDIN, a timer
1306	to display a message once per second, and a condition variable to quit the	1742	to display a message once per second, and a condition variable to quit the
…		…
1500	watcher.	1936	watcher.
1501		1937
1502	=head3 Results	1938	=head3 Results
1503		1939
1504	name watchers bytes create invoke destroy comment	1940	name watchers bytes create invoke destroy comment
1505	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1941	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1506	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1942	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1507	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1943	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1508	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1944	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1509	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1945	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1510	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1946	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1947	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1948	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1511	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1949	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1512	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1950	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1513	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1951	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1514	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1952	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1515		1953
1516	=head3 Discussion	1954	=head3 Discussion
1517		1955
1518	The benchmark does I<not> measure scalability of the event loop very	1956	The benchmark does I<not> measure scalability of the event loop very
1519	well. For example, a select-based event loop (such as the pure perl one)	1957	well. For example, a select-based event loop (such as the pure perl one)
…		…
1544	performance becomes really bad with lots of file descriptors (and few of	1982	performance becomes really bad with lots of file descriptors (and few of
1545	them active), of course, but this was not subject of this benchmark.	1983	them active), of course, but this was not subject of this benchmark.
1546		1984
1547	The C<Event> module has a relatively high setup and callback invocation	1985	The C<Event> module has a relatively high setup and callback invocation
1548	cost, but overall scores in on the third place.	1986	cost, but overall scores in on the third place.
		1987
		1988	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1989	when using its pure perl backend.
1549		1990
1550	C<Glib>'s memory usage is quite a bit higher, but it features a	1991	C<Glib>'s memory usage is quite a bit higher, but it features a
1551	faster callback invocation and overall ends up in the same class as	1992	faster callback invocation and overall ends up in the same class as
1552	C<Event>. However, Glib scales extremely badly, doubling the number of	1993	C<Event>. However, Glib scales extremely badly, doubling the number of
1553	watchers increases the processing time by more than a factor of four,	1994	watchers increases the processing time by more than a factor of four,
…		…
1631	it to another server. This includes deleting the old timeout and creating	2072	it to another server. This includes deleting the old timeout and creating
1632	a new one that moves the timeout into the future.	2073	a new one that moves the timeout into the future.
1633		2074
1634	=head3 Results	2075	=head3 Results
1635		2076
1636	name sockets create request	2077	name sockets create request
1637	EV 20000 69.01 11.16	2078	EV 20000 69.01 11.16
1638	Perl 20000 73.32 35.87	2079	Perl 20000 73.32 35.87
		2080	IOAsync 20000 157.00 98.14 epoll
		2081	IOAsync 20000 159.31 616.06 poll
1639	Event 20000 212.62 257.32	2082	Event 20000 212.62 257.32
1640	Glib 20000 651.16 1896.30	2083	Glib 20000 651.16 1896.30
1641	POE 20000 349.67 12317.24 uses POE::Loop::Event	2084	POE 20000 349.67 12317.24 uses POE::Loop::Event
1642		2085
1643	=head3 Discussion	2086	=head3 Discussion
1644		2087
1645	This benchmark I<does> measure scalability and overall performance of the	2088	This benchmark I<does> measure scalability and overall performance of the
1646	particular event loop.	2089	particular event loop.
…		…
1648	EV is again fastest. Since it is using epoll on my system, the setup time	2091	EV is again fastest. Since it is using epoll on my system, the setup time
1649	is relatively high, though.	2092	is relatively high, though.
1650		2093
1651	Perl surprisingly comes second. It is much faster than the C-based event	2094	Perl surprisingly comes second. It is much faster than the C-based event
1652	loops Event and Glib.	2095	loops Event and Glib.
		2096
		2097	IO::Async performs very well when using its epoll backend, and still quite
		2098	good compared to Glib when using its pure perl backend.
1653		2099
1654	Event suffers from high setup time as well (look at its code and you will	2100	Event suffers from high setup time as well (look at its code and you will
1655	understand why). Callback invocation also has a high overhead compared to	2101	understand why). Callback invocation also has a high overhead compared to
1656	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2102	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1657	uses select or poll in basically all documented configurations.	2103	uses select or poll in basically all documented configurations.
…		…
1720	=item * C-based event loops perform very well with small number of	2166	=item * C-based event loops perform very well with small number of
1721	watchers, as the management overhead dominates.	2167	watchers, as the management overhead dominates.
1722		2168
1723	=back	2169	=back
1724		2170
		2171	=head2 THE IO::Lambda BENCHMARK
		2172
		2173	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2174	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2175	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2176	shouldn't come as a surprise to anybody). As such, the benchmark is
		2177	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2178	very optimal. But how would AnyEvent compare when used without the extra
		2179	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2180
		2181	The benchmark itself creates an echo-server, and then, for 500 times,
		2182	connects to the echo server, sends a line, waits for the reply, and then
		2183	creates the next connection. This is a rather bad benchmark, as it doesn't
		2184	test the efficiency of the framework or much non-blocking I/O, but it is a
		2185	benchmark nevertheless.
		2186
		2187	name runtime
		2188	Lambda/select 0.330 sec
		2189	+ optimized 0.122 sec
		2190	Lambda/AnyEvent 0.327 sec
		2191	+ optimized 0.138 sec
		2192	Raw sockets/select 0.077 sec
		2193	POE/select, components 0.662 sec
		2194	POE/select, raw sockets 0.226 sec
		2195	POE/select, optimized 0.404 sec
		2196
		2197	AnyEvent/select/nb 0.085 sec
		2198	AnyEvent/EV/nb 0.068 sec
		2199	+state machine 0.134 sec
		2200
		2201	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2202	benchmarks actually make blocking connects and use 100% blocking I/O,
		2203	defeating the purpose of an event-based solution. All of the newly
		2204	written AnyEvent benchmarks use 100% non-blocking connects (using
		2205	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2206	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2207	generally require a lot more bookkeeping and event handling than blocking
		2208	connects (which involve a single syscall only).
		2209
		2210	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2211	offers similar expressive power as POE and IO::Lambda, using conventional
		2212	Perl syntax. This means that both the echo server and the client are 100%
		2213	non-blocking, further placing it at a disadvantage.
		2214
		2215	As you can see, the AnyEvent + EV combination even beats the
		2216	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2217	backend easily beats IO::Lambda and POE.
		2218
		2219	And even the 100% non-blocking version written using the high-level (and
		2220	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2221	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2222	in a non-blocking way.
		2223
		2224	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2225	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2226	part of the IO::lambda distribution and were used without any changes.
		2227
		2228
		2229	=head1 SIGNALS
		2230
		2231	AnyEvent currently installs handlers for these signals:
		2232
		2233	=over 4
		2234
		2235	=item SIGCHLD
		2236
		2237	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2238	emulation for event loops that do not support them natively. Also, some
		2239	event loops install a similar handler.
		2240
		2241	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2242	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2243
		2244	=item SIGPIPE
		2245
		2246	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2247	when AnyEvent gets loaded.
		2248
		2249	The rationale for this is that AnyEvent users usually do not really depend
		2250	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2251	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2252	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2253	some random socket.
		2254
		2255	The rationale for installing a no-op handler as opposed to ignoring it is
		2256	that this way, the handler will be restored to defaults on exec.
		2257
		2258	Feel free to install your own handler, or reset it to defaults.
		2259
		2260	=back
		2261
		2262	=cut
		2263
		2264	undef $SIG{CHLD}
		2265	if $SIG{CHLD} eq 'IGNORE';
		2266
		2267	$SIG{PIPE} = sub { }
		2268	unless defined $SIG{PIPE};
		2269
		2270	=head1 RECOMMENDED/OPTIONAL MODULES
		2271
		2272	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2273	it's built-in modules) are required to use it.
		2274
		2275	That does not mean that AnyEvent won't take advantage of some additional
		2276	modules if they are installed.
		2277
		2278	This section epxlains which additional modules will be used, and how they
		2279	affect AnyEvent's operetion.
		2280
		2281	=over 4
		2282
		2283	=item L<Async::Interrupt>
		2284
		2285	This slightly arcane module is used to implement fast signal handling: To
		2286	my knowledge, there is no way to do completely race-free and quick
		2287	signal handling in pure perl. To ensure that signals still get
		2288	delivered, AnyEvent will start an interval timer to wake up perl (and
		2289	catch the signals) with some delay (default is 10 seconds, look for
		2290	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2291
		2292	If this module is available, then it will be used to implement signal
		2293	catching, which means that signals will not be delayed, and the event loop
		2294	will not be interrupted regularly, which is more efficient (And good for
		2295	battery life on laptops).
		2296
		2297	This affects not just the pure-perl event loop, but also other event loops
		2298	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2299
		2300	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2301	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2302	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2303	does nothing for those backends.
		2304
		2305	=item L<EV>
		2306
		2307	This module isn't really "optional", as it is simply one of the backend
		2308	event loops that AnyEvent can use. However, it is simply the best event
		2309	loop available in terms of features, speed and stability: It supports
		2310	the AnyEvent API optimally, implements all the watcher types in XS, does
		2311	automatic timer adjustments even when no monotonic clock is available,
		2312	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2313	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2314	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2315
		2316	=item L<Guard>
		2317
		2318	The guard module, when used, will be used to implement
		2319	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2320	lot less memory), but otherwise doesn't affect guard operation much. It is
		2321	purely used for performance.
		2322
		2323	=item L<JSON> and L<JSON::XS>
		2324
		2325	This module is required when you want to read or write JSON data via
		2326	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2327	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2328
		2329	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2330	installed.
		2331
		2332	=item L<Net::SSLeay>
		2333
		2334	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2335	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2336	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2337
		2338	=item L<Time::HiRes>
		2339
		2340	This module is part of perl since release 5.008. It will be used when the
		2341	chosen event library does not come with a timing source on it's own. The
		2342	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2343	try to use a monotonic clock for timing stability.
		2344
		2345	=back
		2346
1725		2347
1726	=head1 FORK	2348	=head1 FORK
1727		2349
1728	Most event libraries are not fork-safe. The ones who are usually are	2350	Most event libraries are not fork-safe. The ones who are usually are
1729	because they rely on inefficient but fork-safe C<select> or C<poll>	2351	because they rely on inefficient but fork-safe C<select> or C<poll>
1730	calls. Only L<EV> is fully fork-aware.	2352	calls. Only L<EV> is fully fork-aware.
1731		2353
1732	If you have to fork, you must either do so I<before> creating your first	2354	If you have to fork, you must either do so I<before> creating your first
1733	watcher OR you must not use AnyEvent at all in the child.	2355	watcher OR you must not use AnyEvent at all in the child OR you must do
		2356	something completely out of the scope of AnyEvent.
1734		2357
1735		2358
1736	=head1 SECURITY CONSIDERATIONS	2359	=head1 SECURITY CONSIDERATIONS
1737		2360
1738	AnyEvent can be forced to load any event model via	2361	AnyEvent can be forced to load any event model via
…		…
1750	use AnyEvent;	2373	use AnyEvent;
1751		2374
1752	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2375	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1753	be used to probe what backend is used and gain other information (which is	2376	be used to probe what backend is used and gain other information (which is
1754	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2377	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1755	$ENV{PERL_ANYEGENT_STRICT}.	2378	$ENV{PERL_ANYEVENT_STRICT}.
		2379
		2380	Note that AnyEvent will remove I<all> environment variables starting with
		2381	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2382	enabled.
1756		2383
1757		2384
1758	=head1 BUGS	2385	=head1 BUGS
1759		2386
1760	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2387	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1761	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2388	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1762	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2389	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1763	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2390	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1764	pronounced).	2391	pronounced).
1765		2392
1766		2393
1767	=head1 SEE ALSO	2394	=head1 SEE ALSO
1768		2395
…		…
1772	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2399	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1773		2400
1774	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2401	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1775	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2402	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1776	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2403	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1777	L<AnyEvent::Impl::POE>.	2404	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1778		2405
1779	Non-blocking file handles, sockets, TCP clients and	2406	Non-blocking file handles, sockets, TCP clients and
1780	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2407	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1781		2408
1782	Asynchronous DNS: L<AnyEvent::DNS>.	2409	Asynchronous DNS: L<AnyEvent::DNS>.
1783		2410
1784	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2411	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2412	L<Coro::Event>,
1785		2413
1786	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2414	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2415	L<AnyEvent::HTTP>.
1787		2416
1788		2417
1789	=head1 AUTHOR	2418	=head1 AUTHOR
1790		2419
1791	Marc Lehmann <schmorp@schmorp.de>	2420	Marc Lehmann <schmorp@schmorp.de>

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