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Revision 1.253 by root, Tue Jul 21 06:00:47 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 { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
22		39
23	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
24		41
25	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
26	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
27	L<AnyEvent::Intro> manpage.	44	L<AnyEvent::Intro> manpage.
28		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.
		53
29	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
30		55
31	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
32	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
33		58
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	59	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	60	policy> and AnyEvent is I<small and efficient>.
36		61
37	First and foremost, I<AnyEvent is not an event model> itself, it only	62	First and foremost, I<AnyEvent is not an event model> itself, it only
38	interfaces to whatever event model the main program happens to use in a	63	interfaces to whatever event model the main program happens to use, in a
39	pragmatic way. For event models and certain classes of immortals alike,	64	pragmatic way. For event models and certain classes of immortals alike,
40	the statement "there can only be one" is a bitter reality: In general,	65	the statement "there can only be one" is a bitter reality: In general,
41	only one event loop can be active at the same time in a process. AnyEvent	66	only one event loop can be active at the same time in a process. AnyEvent
42	helps hiding the differences between those event loops.	67	cannot change this, but it can hide the differences between those event
		68	loops.
43		69
44	The goal of AnyEvent is to offer module authors the ability to do event	70	The goal of AnyEvent is to offer module authors the ability to do event
45	programming (waiting for I/O or timer events) without subscribing to a	71	programming (waiting for I/O or timer events) without subscribing to a
46	religion, a way of living, and most importantly: without forcing your	72	religion, a way of living, and most importantly: without forcing your
47	module users into the same thing by forcing them to use the same event	73	module users into the same thing by forcing them to use the same event
48	model you use.	74	model you use.
49		75
50	For modules like POE or IO::Async (which is a total misnomer as it is	76	For modules like POE or IO::Async (which is a total misnomer as it is
51	actually doing all I/O I<synchronously>...), using them in your module is	77	actually doing all I/O I<synchronously>...), using them in your module is
52	like joining a cult: After you joined, you are dependent on them and you	78	like joining a cult: After you joined, you are dependent on them and you
53	cannot use anything else, as it is simply incompatible to everything that	79	cannot use anything else, as they are simply incompatible to everything
54	isn't itself. What's worse, all the potential users of your module are	80	that isn't them. What's worse, all the potential users of your
55	I<also> forced to use the same event loop you use.	81	module are I<also> forced to use the same event loop you use.
56		82
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	83	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	84	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
59	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	85	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
60	your module uses one of those, every user of your module has to use it,	86	your module uses one of those, every user of your module has to use it,
61	too. But if your module uses AnyEvent, it works transparently with all	87	too. But if your module uses AnyEvent, it works transparently with all
62	event models it supports (including stuff like POE and IO::Async, as long	88	event models it supports (including stuff like IO::Async, as long as those
63	as those use one of the supported event loops. It is trivial to add new	89	use one of the supported event loops. It is trivial to add new event loops
64	event loops to AnyEvent, too, so it is future-proof).	90	to AnyEvent, too, so it is future-proof).
65		91
66	In addition to being free of having to use I<the one and only true event	92	In addition to being free of having to use I<the one and only true event
67	model>, AnyEvent also is free of bloat and policy: with POE or similar	93	model>, AnyEvent also is free of bloat and policy: with POE or similar
68	modules, you get an enormous amount of code and strict rules you have to	94	modules, you get an enormous amount of code and strict rules you have to
69	follow. AnyEvent, on the other hand, is lean and up to the point, by only	95	follow. AnyEvent, on the other hand, is lean and up to the point, by only
…		…
127	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
128	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
129	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
130	is in control).	156	is in control).
131		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
132	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
133	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
134	to it).	166	to it).
135		167
136	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.
…		…
152	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
153		185
154	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
155	with the following mandatory key-value pairs as arguments:	187	with the following mandatory key-value pairs as arguments:
156		188
157	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	189	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		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
158	for events. C<poll> must be a string that is either C<r> or C<w>,	196	C<poll> must be a string that is either C<r> or C<w>, which creates a
159	which creates a watcher waiting for "r"eadable or "w"ritable events,	197	watcher waiting for "r"eadable or "w"ritable events, respectively.
		198
160	respectively. C<cb> is the callback to invoke each time the file handle	199	C<cb> is the callback to invoke each time the file handle becomes ready.
161	becomes ready.
162		200
163	Although the callback might get passed parameters, their value and	201	Although the callback might get passed parameters, their value and
164	presence is undefined and you cannot rely on them. Portable AnyEvent	202	presence is undefined and you cannot rely on them. Portable AnyEvent
165	callbacks cannot use arguments passed to I/O watcher callbacks.	203	callbacks cannot use arguments passed to I/O watcher callbacks.
166		204
…		…
298	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
299	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
300	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	338	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
301	account.	339	account.
302		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
303	=back	356	=back
304		357
305	=head2 SIGNAL WATCHERS	358	=head2 SIGNAL WATCHERS
306		359
307	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
308	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	361	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
309	be invoked whenever a signal occurs.	362	callback to be invoked whenever a signal occurs.
310		363
311	Although the callback might get passed parameters, their value and	364	Although the callback might get passed parameters, their value and
312	presence is undefined and you cannot rely on them. Portable AnyEvent	365	presence is undefined and you cannot rely on them. Portable AnyEvent
313	callbacks cannot use arguments passed to signal watcher callbacks.	366	callbacks cannot use arguments passed to signal watcher callbacks.
314		367
…		…
316	invocation, and callback invocation will be synchronous. Synchronous means	369	invocation, and callback invocation will be synchronous. Synchronous means
317	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,
318	but it is guaranteed not to interrupt any other callbacks.	371	but it is guaranteed not to interrupt any other callbacks.
319		372
320	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
321	between multiple watchers.	374	between multiple watchers, and AnyEvent will ensure that signals will not
		375	interrupt your program at bad times.
322		376
323	This watcher might use C<%SIG>, so programs overwriting those signals	377	This watcher might use C<%SIG> (depending on the event loop used),
324	directly will likely not work correctly.	378	so programs overwriting those signals directly will likely not work
		379	correctly.
325		380
326	Example: exit on SIGINT	381	Example: exit on SIGINT
327		382
328	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	383	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
329		384
		385	=head3 Signal Races, Delays and Workarounds
		386
		387	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		388	callbacks to signals in a generic way, which is a pity, as you cannot do
		389	race-free signal handling in perl. AnyEvent will try to do it's best, but
		390	in some cases, signals will be delayed. The maximum time a signal might
		391	be delayed is specified in C<$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
330	=head2 CHILD PROCESS WATCHERS	401	=head2 CHILD PROCESS WATCHERS
331		402
332	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.
333		404
334	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
335	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
336	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
337	signal handler for C<SIGCHLD>. The callback will be called with the pid	408	any trace events (stopped/continued).
338	and exit status (as returned by waitpid), so unlike other watcher types,	409
339	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).
340		418
341	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
342	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
343	have exited already (and no SIGCHLD will be sent anymore).	421	have exited already (and no SIGCHLD will be sent anymore).
344		422
345	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
346	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
347	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.
348		429
349	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
350	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
351	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.
352		438
353	Example: fork a process and wait for it	439	Example: fork a process and wait for it
354		440
355	my $done = AnyEvent->condvar;	441	my $done = AnyEvent->condvar;
356		442
…		…
366	);	452	);
367		453
368	# do something else, then wait for process exit	454	# do something else, then wait for process exit
369	$done->recv;	455	$done->recv;
370		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
371	=head2 CONDITION VARIABLES	492	=head2 CONDITION VARIABLES
372		493
373	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
374	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
375	will actively watch for new events and call your callbacks.	496	will actively watch for new events and call your callbacks.
376		497
377	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
378	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).
379		500
380	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
381	because they represent a condition that must become true.	502	because they represent a condition that must become true.
		503
		504	Now is probably a good time to look at the examples further below.
382		505
383	Condition variables can be created by calling the C<< AnyEvent->condvar	506	Condition variables can be created by calling the C<< AnyEvent->condvar
384	>> method, usually without arguments. The only argument pair allowed is	507	>> method, usually without arguments. The only argument pair allowed is
385	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
386	becomes true.	509	becomes true, with the condition variable as the first argument (but not
		510	the results).
387		511
388	After creation, the condition variable is "false" until it becomes "true"	512	After creation, the condition variable is "false" until it becomes "true"
389	by calling the C<send> method (or calling the condition variable as if it	513	by calling the C<send> method (or calling the condition variable as if it
390	were a callback, read about the caveats in the description for the C<<	514	were a callback, read about the caveats in the description for the C<<
391	->send >> method).	515	->send >> method).
…		…
393	Condition variables are similar to callbacks, except that you can	517	Condition variables are similar to callbacks, except that you can
394	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
395	in time where multiple outstanding events have been processed. And yet	519	in time where multiple outstanding events have been processed. And yet
396	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
397	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
398	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.
399		524
400	Condition variables are very useful to signal that something has finished,	525	Condition variables are very useful to signal that something has finished,
401	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,
402	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
403	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
…		…
437	after => 1,	562	after => 1,
438	cb => sub { $result_ready->send },	563	cb => sub { $result_ready->send },
439	);	564	);
440		565
441	# this "blocks" (while handling events) till the callback	566	# this "blocks" (while handling events) till the callback
442	# calls send	567	# calls -<send
443	$result_ready->recv;	568	$result_ready->recv;
444		569
445	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
446	condition variables are also code references.	571	variables are also callable directly.
447		572
448	my $done = AnyEvent->condvar;	573	my $done = AnyEvent->condvar;
449	my $delay = AnyEvent->timer (after => 5, cb => $done);	574	my $delay = AnyEvent->timer (after => 5, cb => $done);
450	$done->recv;	575	$done->recv;
		576
		577	Example: Imagine an API that returns a condvar and doesn't support
		578	callbacks. This is how you make a synchronous call, for example from
		579	the main program:
		580
		581	use AnyEvent::CouchDB;
		582
		583	...
		584
		585	my @info = $couchdb->info->recv;
		586
		587	And this is how you would just set a callback to be called whenever the
		588	results are available:
		589
		590	$couchdb->info->cb (sub {
		591	my @info = $_[0]->recv;
		592	});
451		593
452	=head3 METHODS FOR PRODUCERS	594	=head3 METHODS FOR PRODUCERS
453		595
454	These methods should only be used by the producing side, i.e. the	596	These methods should only be used by the producing side, i.e. the
455	code/module that eventually sends the signal. Note that it is also	597	code/module that eventually sends the signal. Note that it is also
…		…
468	immediately from within send.	610	immediately from within send.
469		611
470	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
471	future C<< ->recv >> calls.	613	future C<< ->recv >> calls.
472		614
473	Condition variables are overloaded so one can call them directly	615	Condition variables are overloaded so one can call them directly (as if
474	(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
475	C<send>. Note, however, that many C-based event loops do not handle	617	C<send>.
476	overloading, so as tempting as it may be, passing a condition variable
477	instead of a callback does not work. Both the pure perl and EV loops
478	support overloading, however, as well as all functions that use perl to
479	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
480	example).
481		618
482	=item $cv->croak ($error)	619	=item $cv->croak ($error)
483		620
484	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
485	C<Carp::croak> with the given error message/object/scalar.	622	C<Carp::croak> with the given error message/object/scalar.
486		623
487	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
488	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.
489		630
490	=item $cv->begin ([group callback])	631	=item $cv->begin ([group callback])
491		632
492	=item $cv->end	633	=item $cv->end
493
494	These two methods are EXPERIMENTAL and MIGHT CHANGE.
495		634
496	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
497	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
498	to use a condition variable for the whole process.	637	to use a condition variable for the whole process.
499		638
…		…
501	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
502	>>, 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
503	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
504	callback was set, C<send> will be called without any arguments.	643	callback was set, C<send> will be called without any arguments.
505		644
506	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:
507		676
508	my $cv = AnyEvent->condvar;	677	my $cv = AnyEvent->condvar;
509		678
510	my %result;	679	my %result;
511	$cv->begin (sub { $cv->send (\%result) });	680	$cv->begin (sub { $cv->send (\%result) });
…		…
531	loop, which serves two important purposes: first, it sets the callback	700	loop, which serves two important purposes: first, it sets the callback
532	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
533	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
534	doesn't execute once).	703	doesn't execute once).
535		704
536	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
537	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
538	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
539	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>.
540		710
541	=back	711	=back
542		712
543	=head3 METHODS FOR CONSUMERS	713	=head3 METHODS FOR CONSUMERS
544		714
…		…
560	function will call C<croak>.	730	function will call C<croak>.
561		731
562	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,
563	in scalar context only the first one will be returned.	733	in scalar context only the first one will be returned.
564		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
565	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
566	(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
567	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
568	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
569	condition variables with some kind of request results and supporting	746	condition variables with some kind of request results and supporting
570	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,
571	while still supporting blocking waits if the caller so desires).	748	while still supporting blocking waits if the caller so desires).
572		749
573	Another reason I<never> to C<< ->recv >> in a module is that you cannot
574	sensibly have two C<< ->recv >>'s in parallel, as that would require
575	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
576	can supply.
577
578	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
579	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
580	versions and also integrates coroutines into AnyEvent, making blocking
581	C<< ->recv >> calls perfectly safe as long as they are done from another
582	coroutine (one that doesn't run the event loop).
583
584	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
585	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
586	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
587	waits otherwise.	753	waits otherwise.
588		754
589	=item $bool = $cv->ready	755	=item $bool = $cv->ready
590		756
591	Returns true when the condition is "true", i.e. whether C<send> or	757	Returns true when the condition is "true", i.e. whether C<send> or
592	C<croak> have been called.	758	C<croak> have been called.
593		759
594	=item $cb = $cv->cb ([new callback])	760	=item $cb = $cv->cb ($cb->($cv))
595		761
596	This is a mutator function that returns the callback set and optionally	762	This is a mutator function that returns the callback set and optionally
597	replaces it before doing so.	763	replaces it before doing so.
598		764
599	The callback will be called when the condition becomes "true", i.e. when	765	The callback will be called when the condition becomes "true", i.e. when
…		…
601	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
602	is guaranteed not to block.	768	is guaranteed not to block.
603		769
604	=back	770	=back
605		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
606	=head1 GLOBAL VARIABLES AND FUNCTIONS	839	=head1 GLOBAL VARIABLES AND FUNCTIONS
607		840
		841	These are not normally required to use AnyEvent, but can be useful to
		842	write AnyEvent extension modules.
		843
608	=over 4	844	=over 4
609		845
610	=item $AnyEvent::MODEL	846	=item $AnyEvent::MODEL
611		847
612	Contains C<undef> until the first watcher is being created. Then it	848	Contains C<undef> until the first watcher is being created, before the
		849	backend has been autodetected.
		850
613	contains the event model that is being used, which is the name of the	851	Afterwards it contains the event model that is being used, which is the
614	Perl class implementing the model. This class is usually one of the	852	name of the Perl class implementing the model. This class is usually one
615	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	853	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
616	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	854	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
617		855	will be C<urxvt::anyevent>).
618	The known classes so far are:
619
620	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
621	AnyEvent::Impl::Event based on Event, second best choice.
622	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
623	AnyEvent::Impl::Glib based on Glib, third-best choice.
624	AnyEvent::Impl::Tk based on Tk, very bad choice.
625	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
626	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
627	AnyEvent::Impl::POE based on POE, not generic enough for full support.
628
629	There is no support for WxWidgets, as WxWidgets has no support for
630	watching file handles. However, you can use WxWidgets through the
631	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
632	second, which was considered to be too horrible to even consider for
633	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
634	it's adaptor.
635
636	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
637	autodetecting them.
638		856
639	=item AnyEvent::detect	857	=item AnyEvent::detect
640		858
641	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	859	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
642	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
643	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
644	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>.
645		866
646	=item $guard = AnyEvent::post_detect { BLOCK }	867	=item $guard = AnyEvent::post_detect { BLOCK }
647		868
648	Arranges for the code block to be executed as soon as the event model is	869	Arranges for the code block to be executed as soon as the event model is
649	autodetected (or immediately if this has already happened).	870	autodetected (or immediately if this has already happened).
650		871
		872	The block will be executed I<after> the actual backend has been detected
		873	(C<$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.
		882
651	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
652	that automatically removes the callback again when it is destroyed. See	884	that automatically removes the callback again when it is destroyed (or
		885	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
653	L<Coro::BDB> for a case where this is useful.	886	a case where this is useful.
		887
		888	Example: Create a watcher for the IO::AIO module and store it in
		889	C<$WATCHER>. Only do so after the event loop is initialised, though.
		890
		891	our WATCHER;
		892
		893	my $guard = AnyEvent::post_detect {
		894	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		895	};
		896
		897	# the ||= is important in case post_detect immediately runs the block,
		898	# as to not clobber the newly-created watcher. assigning both watcher and
		899	# post_detect guard to the same variable has the advantage of users being
		900	# able to just C<undef $WATCHER> if the watcher causes them grief.
		901
		902	$WATCHER ||= $guard;
654		903
655	=item @AnyEvent::post_detect	904	=item @AnyEvent::post_detect
656		905
657	If there are any code references in this array (you can C<push> to it	906	If there are any code references in this array (you can C<push> to it
658	before or after loading AnyEvent), then they will called directly after	907	before or after loading AnyEvent), then they will called directly after
659	the event loop has been chosen.	908	the event loop has been chosen.
660		909
661	You should check C<$AnyEvent::MODEL> before adding to this array, though:	910	You should check C<$AnyEvent::MODEL> before adding to this array, though:
662	if it contains a true value then the event loop has already been detected,	911	if it is defined then the event loop has already been detected, and the
663	and the array will be ignored.	912	array will be ignored.
664		913
665	Best use C<AnyEvent::post_detect { BLOCK }> instead.	914	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		915	it,as it takes care of these details.
		916
		917	This variable is mainly useful for modules that can do something useful
		918	when AnyEvent is used and thus want to know when it is initialised, but do
		919	not need to even load it by default. This array provides the means to hook
		920	into AnyEvent passively, without loading it.
666		921
667	=back	922	=back
668		923
669	=head1 WHAT TO DO IN A MODULE	924	=head1 WHAT TO DO IN A MODULE
670		925
…		…
725		980
726		981
727	=head1 OTHER MODULES	982	=head1 OTHER MODULES
728		983
729	The following is a non-exhaustive list of additional modules that use	984	The following is a non-exhaustive list of additional modules that use
730	AnyEvent and can therefore be mixed easily with other AnyEvent modules	985	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
731	in the same program. Some of the modules come with AnyEvent, some are	986	modules and other event loops in the same program. Some of the modules
732	available via CPAN.	987	come with AnyEvent, most are available via CPAN.
733		988
734	=over 4	989	=over 4
735		990
736	=item L<AnyEvent::Util>	991	=item L<AnyEvent::Util>
737		992
…		…
746		1001
747	=item L<AnyEvent::Handle>	1002	=item L<AnyEvent::Handle>
748		1003
749	Provide read and write buffers, manages watchers for reads and writes,	1004	Provide read and write buffers, manages watchers for reads and writes,
750	supports raw and formatted I/O, I/O queued and fully transparent and	1005	supports raw and formatted I/O, I/O queued and fully transparent and
751	non-blocking SSL/TLS.	1006	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
752		1007
753	=item L<AnyEvent::DNS>	1008	=item L<AnyEvent::DNS>
754		1009
755	Provides rich asynchronous DNS resolver capabilities.	1010	Provides rich asynchronous DNS resolver capabilities.
756		1011
…		…
784		1039
785	=item L<AnyEvent::GPSD>	1040	=item L<AnyEvent::GPSD>
786		1041
787	A non-blocking interface to gpsd, a daemon delivering GPS information.	1042	A non-blocking interface to gpsd, a daemon delivering GPS information.
788		1043
		1044	=item L<AnyEvent::IRC>
		1045
		1046	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1047
		1048	=item L<AnyEvent::XMPP>
		1049
		1050	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1051	Net::XMPP2>.
		1052
789	=item L<AnyEvent::IGS>	1053	=item L<AnyEvent::IGS>
790		1054
791	A non-blocking interface to the Internet Go Server protocol (used by	1055	A non-blocking interface to the Internet Go Server protocol (used by
792	L<App::IGS>).	1056	L<App::IGS>).
793		1057
794	=item L<Net::IRC3>
795
796	AnyEvent based IRC client module family.
797
798	=item L<Net::XMPP2>
799
800	AnyEvent based XMPP (Jabber protocol) module family.
801
802	=item L<Net::FCP>	1058	=item L<Net::FCP>
803		1059
804	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1060	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
805	of AnyEvent.	1061	of AnyEvent.
806		1062
…		…
810		1066
811	=item L<Coro>	1067	=item L<Coro>
812		1068
813	Has special support for AnyEvent via L<Coro::AnyEvent>.	1069	Has special support for AnyEvent via L<Coro::AnyEvent>.
814		1070
815	=item L<IO::Lambda>
816
817	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
818
819	=back	1071	=back
820		1072
821	=cut	1073	=cut
822		1074
823	package AnyEvent;	1075	package AnyEvent;
824		1076
		1077	# basically a tuned-down version of common::sense
		1078	sub common_sense {
825	no warnings;	1079	# no warnings
826	use strict;	1080	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1081	# use strict vars subs
		1082	$^H |= 0x00000600;
		1083	}
827		1084
		1085	BEGIN { AnyEvent::common_sense }
		1086
828	use Carp;	1087	use Carp ();
829		1088
830	our $VERSION = 4.2;	1089	our $VERSION = 4.86;
831	our $MODEL;	1090	our $MODEL;
832		1091
833	our $AUTOLOAD;	1092	our $AUTOLOAD;
834	our @ISA;	1093	our @ISA;
835		1094
836	our @REGISTRY;	1095	our @REGISTRY;
837		1096
838	our $WIN32;	1097	our $WIN32;
839		1098
		1099	our $VERBOSE;
		1100
840	BEGIN {	1101	BEGIN {
841	my $win32 = ! ! ($^O =~ /mswin32/i);	1102	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
842	eval "sub WIN32(){ $win32 }";	1103	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
843	}
844		1104
		1105	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1106	if ${^TAINT};
		1107
845	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1108	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1109
		1110	}
		1111
		1112	our $MAX_SIGNAL_LATENCY = 10;
846		1113
847	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1114	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
848		1115
849	{	1116	{
850	my $idx;	1117	my $idx;
…		…
858	[Event:: => AnyEvent::Impl::Event::],	1125	[Event:: => AnyEvent::Impl::Event::],
859	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1126	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
860	# everything below here will not be autoprobed	1127	# everything below here will not be autoprobed
861	# as the pureperl backend should work everywhere	1128	# as the pureperl backend should work everywhere
862	# and is usually faster	1129	# and is usually faster
863	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
864	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1130	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
865	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1131	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1132	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
866	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1133	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
867	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1134	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
868	[Wx:: => AnyEvent::Impl::POE::],	1135	[Wx:: => AnyEvent::Impl::POE::],
869	[Prima:: => AnyEvent::Impl::POE::],	1136	[Prima:: => AnyEvent::Impl::POE::],
		1137	# IO::Async is just too broken - we would need workarounds for its
		1138	# byzantine signal and broken child handling, among others.
		1139	# IO::Async is rather hard to detect, as it doesn't have any
		1140	# obvious default class.
		1141	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1142	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1143	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
870	);	1144	);
871		1145
872	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1146	our %method = map +($_ => 1),
		1147	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
873		1148
874	our @post_detect;	1149	our @post_detect;
875		1150
876	sub post_detect(&) {	1151	sub post_detect(&) {
877	my ($cb) = @_;	1152	my ($cb) = @_;
878		1153
879	if ($MODEL) {	1154	if ($MODEL) {
880	$cb->();	1155	$cb->();
881		1156
882	1	1157	undef
883	} else {	1158	} else {
884	push @post_detect, $cb;	1159	push @post_detect, $cb;
885		1160
886	defined wantarray	1161	defined wantarray
887	? bless \$cb, "AnyEvent::Util::PostDetect"	1162	? bless \$cb, "AnyEvent::Util::postdetect"
888	: ()	1163	: ()
889	}	1164	}
890	}	1165	}
891		1166
892	sub AnyEvent::Util::PostDetect::DESTROY {	1167	sub AnyEvent::Util::postdetect::DESTROY {
893	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1168	@post_detect = grep $_ != ${$_[0]}, @post_detect;
894	}	1169	}
895		1170
896	sub detect() {	1171	sub detect() {
897	unless ($MODEL) {	1172	unless ($MODEL) {
898	no strict 'refs';
899	local $SIG{__DIE__};	1173	local $SIG{__DIE__};
900		1174
901	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1175	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
902	my $model = "AnyEvent::Impl::$1";	1176	my $model = "AnyEvent::Impl::$1";
903	if (eval "require $model") {	1177	if (eval "require $model") {
904	$MODEL = $model;	1178	$MODEL = $model;
905	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1179	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
906	} else {	1180	} else {
907	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1181	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
908	}	1182	}
909	}	1183	}
910		1184
911	# check for already loaded models	1185	# check for already loaded models
912	unless ($MODEL) {	1186	unless ($MODEL) {
913	for (@REGISTRY, @models) {	1187	for (@REGISTRY, @models) {
914	my ($package, $model) = @$_;	1188	my ($package, $model) = @$_;
915	if (${"$package\::VERSION"} > 0) {	1189	if (${"$package\::VERSION"} > 0) {
916	if (eval "require $model") {	1190	if (eval "require $model") {
917	$MODEL = $model;	1191	$MODEL = $model;
918	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1192	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
919	last;	1193	last;
920	}	1194	}
921	}	1195	}
922	}	1196	}
923		1197
…		…
928	my ($package, $model) = @$_;	1202	my ($package, $model) = @$_;
929	if (eval "require $package"	1203	if (eval "require $package"
930	and ${"$package\::VERSION"} > 0	1204	and ${"$package\::VERSION"} > 0
931	and eval "require $model") {	1205	and eval "require $model") {
932	$MODEL = $model;	1206	$MODEL = $model;
933	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1207	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
934	last;	1208	last;
935	}	1209	}
936	}	1210	}
937		1211
938	$MODEL	1212	$MODEL
939	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1213	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
940	}	1214	}
941	}	1215	}
942		1216
		1217	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1218
943	unshift @ISA, $MODEL;	1219	unshift @ISA, $MODEL;
944	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1220
		1221	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
945		1222
946	(shift @post_detect)->() while @post_detect;	1223	(shift @post_detect)->() while @post_detect;
947	}	1224	}
948		1225
949	$MODEL	1226	$MODEL
…		…
951		1228
952	sub AUTOLOAD {	1229	sub AUTOLOAD {
953	(my $func = $AUTOLOAD) =~ s/.*://;	1230	(my $func = $AUTOLOAD) =~ s/.*://;
954		1231
955	$method{$func}	1232	$method{$func}
956	or croak "$func: not a valid method for AnyEvent objects";	1233	or Carp::croak "$func: not a valid method for AnyEvent objects";
957		1234
958	detect unless $MODEL;	1235	detect unless $MODEL;
959		1236
960	my $class = shift;	1237	my $class = shift;
961	$class->$func (@_);	1238	$class->$func (@_);
962	}	1239	}
963		1240
		1241	# utility function to dup a filehandle. this is used by many backends
		1242	# to support binding more than one watcher per filehandle (they usually
		1243	# allow only one watcher per fd, so we dup it to get a different one).
		1244	sub _dupfh($$;$$) {
		1245	my ($poll, $fh, $r, $w) = @_;
		1246
		1247	# cygwin requires the fh mode to be matching, unix doesn't
		1248	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1249
		1250	open my $fh2, $mode, $fh
		1251	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1252
		1253	# we assume CLOEXEC is already set by perl in all important cases
		1254
		1255	($fh2, $rw)
		1256	}
		1257
964	package AnyEvent::Base;	1258	package AnyEvent::Base;
965		1259
966	# default implementation for now and time	1260	# default implementations for many methods
967		1261
968	use Time::HiRes ();	1262	sub _time {
		1263	# probe for availability of Time::HiRes
		1264	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1265	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1266	*_time = \&Time::HiRes::time;
		1267	# if (eval "use POSIX (); (POSIX::times())...
		1268	} else {
		1269	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1270	*_time = sub { time }; # epic fail
		1271	}
969		1272
970	sub time { Time::HiRes::time }	1273	&_time
971	sub now { Time::HiRes::time }	1274	}
		1275
		1276	sub time { _time }
		1277	sub now { _time }
		1278	sub now_update { }
972		1279
973	# default implementation for ->condvar	1280	# default implementation for ->condvar
974		1281
975	sub condvar {	1282	sub condvar {
976	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1283	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
977	}	1284	}
978		1285
979	# default implementation for ->signal	1286	# default implementation for ->signal
980		1287
981	our %SIG_CB;	1288	our $HAVE_ASYNC_INTERRUPT;
		1289	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1290	our (%SIG_ASY, %SIG_ASY_W);
		1291	our ($SIG_COUNT, $SIG_TW);
982		1292
		1293	sub _signal_exec {
		1294	$HAVE_ASYNC_INTERRUPT
		1295	? $SIGPIPE_R->drain
		1296	: sysread $SIGPIPE_R, my $dummy, 9;
		1297
		1298	while (%SIG_EV) {
		1299	for (keys %SIG_EV) {
		1300	delete $SIG_EV{$_};
		1301	$_->() for values %{ $SIG_CB{$_} || {} };
		1302	}
		1303	}
		1304	}
		1305
		1306	# install a dumym wakeupw atcher to reduce signal catching latency
		1307	sub _sig_add() {
		1308	unless ($SIG_COUNT++) {
		1309	# try to align timer on a full-second boundary, if possible
		1310	my $NOW = AnyEvent->now;
		1311
		1312	$SIG_TW = AnyEvent->timer (
		1313	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1314	interval => $MAX_SIGNAL_LATENCY,
		1315	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1316	);
		1317	}
		1318	}
		1319
		1320	sub _sig_del {
		1321	undef $SIG_TW
		1322	unless --$SIG_COUNT;
		1323	}
		1324
983	sub signal {	1325	sub _signal {
984	my (undef, %arg) = @_;	1326	my (undef, %arg) = @_;
985		1327
986	my $signal = uc $arg{signal}	1328	my $signal = uc $arg{signal}
987	or Carp::croak "required option 'signal' is missing";	1329	or Carp::croak "required option 'signal' is missing";
988		1330
989	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1331	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1332
		1333	if ($HAVE_ASYNC_INTERRUPT) {
		1334	# async::interrupt
		1335
		1336	$SIG_ASY{$signal} ||= do {
		1337	my $asy = new Async::Interrupt
		1338	cb => sub { undef $SIG_EV{$signal} },
		1339	signal => $signal,
		1340	pipe => [$SIGPIPE_R->filenos],
		1341	;
		1342	$asy->pipe_autodrain (0);
		1343
		1344	$asy
		1345	};
		1346
		1347	} else {
		1348	# pure perl
		1349
990	$SIG{$signal} ||= sub {	1350	$SIG{$signal} ||= sub {
991	$_->() for values %{ $SIG_CB{$signal} || {} };	1351	local $!;
		1352	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1353	undef $SIG_EV{$signal};
		1354	};
		1355
		1356	# can't do signal processing without introducing races in pure perl,
		1357	# so limit the signal latency.
		1358	_sig_add;
992	};	1359	}
993		1360
994	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1361	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
995	}	1362	}
996		1363
		1364	sub signal {
		1365	# probe for availability of Async::Interrupt
		1366	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1367	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1368
		1369	$HAVE_ASYNC_INTERRUPT = 1;
		1370	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1371	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1372
		1373	} else {
		1374	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1375
		1376	require Fcntl;
		1377
		1378	if (AnyEvent::WIN32) {
		1379	require AnyEvent::Util;
		1380
		1381	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1382	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1383	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1384	} else {
		1385	pipe $SIGPIPE_R, $SIGPIPE_W;
		1386	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1387	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1388
		1389	# not strictly required, as $^F is normally 2, but let's make sure...
		1390	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1391	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1392	}
		1393
		1394	$SIGPIPE_R
		1395	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1396
		1397	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1398	}
		1399
		1400	*signal = \&_signal;
		1401	&signal
		1402	}
		1403
997	sub AnyEvent::Base::Signal::DESTROY {	1404	sub AnyEvent::Base::signal::DESTROY {
998	my ($signal, $cb) = @{$_[0]};	1405	my ($signal, $cb) = @{$_[0]};
999		1406
		1407	_sig_del;
		1408
1000	delete $SIG_CB{$signal}{$cb};	1409	delete $SIG_CB{$signal}{$cb};
1001		1410
		1411	$HAVE_ASYNC_INTERRUPT
		1412	? delete $SIG_ASY{$signal}
		1413	: # delete doesn't work with older perls - they then
		1414	# print weird messages, or just unconditionally exit
		1415	# instead of getting the default action.
		1416	undef $SIG{$signal}
1002	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1417	unless keys %{ $SIG_CB{$signal} };
1003	}	1418	}
1004		1419
1005	# default implementation for ->child	1420	# default implementation for ->child
1006		1421
1007	our %PID_CB;	1422	our %PID_CB;
1008	our $CHLD_W;	1423	our $CHLD_W;
1009	our $CHLD_DELAY_W;	1424	our $CHLD_DELAY_W;
1010	our $PID_IDLE;
1011	our $WNOHANG;	1425	our $WNOHANG;
1012		1426
1013	sub _child_wait {	1427	sub _sigchld {
1014	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1428	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1429	$_->($pid, $?)
1015	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1430	for values %{ $PID_CB{$pid} || {} },
1016	(values %{ $PID_CB{0} || {} });	1431	values %{ $PID_CB{0} || {} };
1017	}	1432	}
1018
1019	undef $PID_IDLE;
1020	}
1021
1022	sub _sigchld {
1023	# make sure we deliver these changes "synchronous" with the event loop.
1024	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1025	undef $CHLD_DELAY_W;
1026	&_child_wait;
1027	});
1028	}	1433	}
1029		1434
1030	sub child {	1435	sub child {
1031	my (undef, %arg) = @_;	1436	my (undef, %arg) = @_;
1032		1437
1033	defined (my $pid = $arg{pid} + 0)	1438	defined (my $pid = $arg{pid} + 0)
1034	or Carp::croak "required option 'pid' is missing";	1439	or Carp::croak "required option 'pid' is missing";
1035		1440
1036	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1441	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1037		1442
1038	unless ($WNOHANG) {	1443	# WNOHANG is almost cetrainly 1 everywhere
		1444	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1445	? 1
1039	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1446	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1040	}
1041		1447
1042	unless ($CHLD_W) {	1448	unless ($CHLD_W) {
1043	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1449	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1044	# child could be a zombie already, so make at least one round	1450	# child could be a zombie already, so make at least one round
1045	&_sigchld;	1451	&_sigchld;
1046	}	1452	}
1047		1453
1048	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1454	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1049	}	1455	}
1050		1456
1051	sub AnyEvent::Base::Child::DESTROY {	1457	sub AnyEvent::Base::child::DESTROY {
1052	my ($pid, $cb) = @{$_[0]};	1458	my ($pid, $cb) = @{$_[0]};
1053		1459
1054	delete $PID_CB{$pid}{$cb};	1460	delete $PID_CB{$pid}{$cb};
1055	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1461	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1056		1462
1057	undef $CHLD_W unless keys %PID_CB;	1463	undef $CHLD_W unless keys %PID_CB;
1058	}	1464	}
1059		1465
		1466	# idle emulation is done by simply using a timer, regardless
		1467	# of whether the process is idle or not, and not letting
		1468	# the callback use more than 50% of the time.
		1469	sub idle {
		1470	my (undef, %arg) = @_;
		1471
		1472	my ($cb, $w, $rcb) = $arg{cb};
		1473
		1474	$rcb = sub {
		1475	if ($cb) {
		1476	$w = _time;
		1477	&$cb;
		1478	$w = _time - $w;
		1479
		1480	# never use more then 50% of the time for the idle watcher,
		1481	# within some limits
		1482	$w = 0.0001 if $w < 0.0001;
		1483	$w = 5 if $w > 5;
		1484
		1485	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1486	} else {
		1487	# clean up...
		1488	undef $w;
		1489	undef $rcb;
		1490	}
		1491	};
		1492
		1493	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1494
		1495	bless \\$cb, "AnyEvent::Base::idle"
		1496	}
		1497
		1498	sub AnyEvent::Base::idle::DESTROY {
		1499	undef $${$_[0]};
		1500	}
		1501
1060	package AnyEvent::CondVar;	1502	package AnyEvent::CondVar;
1061		1503
1062	our @ISA = AnyEvent::CondVar::Base::;	1504	our @ISA = AnyEvent::CondVar::Base::;
1063		1505
1064	package AnyEvent::CondVar::Base;	1506	package AnyEvent::CondVar::Base;
1065		1507
1066	use overload	1508	#use overload
1067	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1509	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1068	fallback => 1;	1510	# fallback => 1;
		1511
		1512	# save 300+ kilobytes by dirtily hardcoding overloading
		1513	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1514	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1515	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1516	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1517
		1518	our $WAITING;
1069		1519
1070	sub _send {	1520	sub _send {
1071	# nop	1521	# nop
1072	}	1522	}
1073		1523
…		…
1086	sub ready {	1536	sub ready {
1087	$_[0]{_ae_sent}	1537	$_[0]{_ae_sent}
1088	}	1538	}
1089		1539
1090	sub _wait {	1540	sub _wait {
		1541	$WAITING
		1542	and !$_[0]{_ae_sent}
		1543	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1544
		1545	local $WAITING = 1;
1091	AnyEvent->one_event while !$_[0]{_ae_sent};	1546	AnyEvent->one_event while !$_[0]{_ae_sent};
1092	}	1547	}
1093		1548
1094	sub recv {	1549	sub recv {
1095	$_[0]->_wait;	1550	$_[0]->_wait;
…		…
1114	}	1569	}
1115		1570
1116	# undocumented/compatibility with pre-3.4	1571	# undocumented/compatibility with pre-3.4
1117	*broadcast = \&send;	1572	*broadcast = \&send;
1118	*wait = \&_wait;	1573	*wait = \&_wait;
		1574
		1575	=head1 ERROR AND EXCEPTION HANDLING
		1576
		1577	In general, AnyEvent does not do any error handling - it relies on the
		1578	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1579	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1580	checking of all AnyEvent methods, however, which is highly useful during
		1581	development.
		1582
		1583	As for exception handling (i.e. runtime errors and exceptions thrown while
		1584	executing a callback), this is not only highly event-loop specific, but
		1585	also not in any way wrapped by this module, as this is the job of the main
		1586	program.
		1587
		1588	The pure perl event loop simply re-throws the exception (usually
		1589	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1590	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1591	so on.
		1592
		1593	=head1 ENVIRONMENT VARIABLES
		1594
		1595	The following environment variables are used by this module or its
		1596	submodules.
		1597
		1598	Note that AnyEvent will remove I<all> environment variables starting with
		1599	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1600	enabled.
		1601
		1602	=over 4
		1603
		1604	=item C<PERL_ANYEVENT_VERBOSE>
		1605
		1606	By default, AnyEvent will be completely silent except in fatal
		1607	conditions. You can set this environment variable to make AnyEvent more
		1608	talkative.
		1609
		1610	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1611	conditions, such as not being able to load the event model specified by
		1612	C<PERL_ANYEVENT_MODEL>.
		1613
		1614	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1615	model it chooses.
		1616
		1617	When set to C<8> or higher, then AnyEvent will report extra information on
		1618	which optional modules it loads and how it implements certain features.
		1619
		1620	=item C<PERL_ANYEVENT_STRICT>
		1621
		1622	AnyEvent does not do much argument checking by default, as thorough
		1623	argument checking is very costly. Setting this variable to a true value
		1624	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1625	check the arguments passed to most method calls. If it finds any problems,
		1626	it will croak.
		1627
		1628	In other words, enables "strict" mode.
		1629
		1630	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1631	>>, it is definitely recommended to keep it off in production. Keeping
		1632	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1633	can be very useful, however.
		1634
		1635	=item C<PERL_ANYEVENT_MODEL>
		1636
		1637	This can be used to specify the event model to be used by AnyEvent, before
		1638	auto detection and -probing kicks in. It must be a string consisting
		1639	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1640	and the resulting module name is loaded and if the load was successful,
		1641	used as event model. If it fails to load AnyEvent will proceed with
		1642	auto detection and -probing.
		1643
		1644	This functionality might change in future versions.
		1645
		1646	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1647	could start your program like this:
		1648
		1649	PERL_ANYEVENT_MODEL=Perl perl ...
		1650
		1651	=item C<PERL_ANYEVENT_PROTOCOLS>
		1652
		1653	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1654	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1655	of auto probing).
		1656
		1657	Must be set to a comma-separated list of protocols or address families,
		1658	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1659	used, and preference will be given to protocols mentioned earlier in the
		1660	list.
		1661
		1662	This variable can effectively be used for denial-of-service attacks
		1663	against local programs (e.g. when setuid), although the impact is likely
		1664	small, as the program has to handle conenction and other failures anyways.
		1665
		1666	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1667	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1668	- only support IPv4, never try to resolve or contact IPv6
		1669	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1670	IPv6, but prefer IPv6 over IPv4.
		1671
		1672	=item C<PERL_ANYEVENT_EDNS0>
		1673
		1674	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1675	for DNS. This extension is generally useful to reduce DNS traffic, but
		1676	some (broken) firewalls drop such DNS packets, which is why it is off by
		1677	default.
		1678
		1679	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1680	EDNS0 in its DNS requests.
		1681
		1682	=item C<PERL_ANYEVENT_MAX_FORKS>
		1683
		1684	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1685	will create in parallel.
		1686
		1687	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1688
		1689	The default value for the C<max_outstanding> parameter for the default DNS
		1690	resolver - this is the maximum number of parallel DNS requests that are
		1691	sent to the DNS server.
		1692
		1693	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1694
		1695	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1696	configuration) in the default resolver. When set to the empty string, no
		1697	default config will be used.
		1698
		1699	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1700
		1701	When neither C<ca_file> nor C<ca_path> was specified during
		1702	L<AnyEvent::TLS> context creation, and either of these environment
		1703	variables exist, they will be used to specify CA certificate locations
		1704	instead of a system-dependent default.
		1705
		1706	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1707
		1708	When these are set to C<1>, then the respective modules are not
		1709	loaded. Mostly good for testing AnyEvent itself.
		1710
		1711	=back
1119		1712
1120	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1713	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1121		1714
1122	This is an advanced topic that you do not normally need to use AnyEvent in	1715	This is an advanced topic that you do not normally need to use AnyEvent in
1123	a module. This section is only of use to event loop authors who want to	1716	a module. This section is only of use to event loop authors who want to
…		…
1157		1750
1158	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1751	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1159	condition variables: code blocking while waiting for a condition will	1752	condition variables: code blocking while waiting for a condition will
1160	C<die>. This still works with most modules/usages, and blocking calls must	1753	C<die>. This still works with most modules/usages, and blocking calls must
1161	not be done in an interactive application, so it makes sense.	1754	not be done in an interactive application, so it makes sense.
1162
1163	=head1 ENVIRONMENT VARIABLES
1164
1165	The following environment variables are used by this module:
1166
1167	=over 4
1168
1169	=item C<PERL_ANYEVENT_VERBOSE>
1170
1171	By default, AnyEvent will be completely silent except in fatal
1172	conditions. You can set this environment variable to make AnyEvent more
1173	talkative.
1174
1175	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1176	conditions, such as not being able to load the event model specified by
1177	C<PERL_ANYEVENT_MODEL>.
1178
1179	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1180	model it chooses.
1181
1182	=item C<PERL_ANYEVENT_MODEL>
1183
1184	This can be used to specify the event model to be used by AnyEvent, before
1185	auto detection and -probing kicks in. It must be a string consisting
1186	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1187	and the resulting module name is loaded and if the load was successful,
1188	used as event model. If it fails to load AnyEvent will proceed with
1189	auto detection and -probing.
1190
1191	This functionality might change in future versions.
1192
1193	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1194	could start your program like this:
1195
1196	PERL_ANYEVENT_MODEL=Perl perl ...
1197
1198	=item C<PERL_ANYEVENT_PROTOCOLS>
1199
1200	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1201	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1202	of auto probing).
1203
1204	Must be set to a comma-separated list of protocols or address families,
1205	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1206	used, and preference will be given to protocols mentioned earlier in the
1207	list.
1208
1209	This variable can effectively be used for denial-of-service attacks
1210	against local programs (e.g. when setuid), although the impact is likely
1211	small, as the program has to handle connection errors already-
1212
1213	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1214	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1215	- only support IPv4, never try to resolve or contact IPv6
1216	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1217	IPv6, but prefer IPv6 over IPv4.
1218
1219	=item C<PERL_ANYEVENT_EDNS0>
1220
1221	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1222	for DNS. This extension is generally useful to reduce DNS traffic, but
1223	some (broken) firewalls drop such DNS packets, which is why it is off by
1224	default.
1225
1226	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1227	EDNS0 in its DNS requests.
1228
1229	=item C<PERL_ANYEVENT_MAX_FORKS>
1230
1231	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1232	will create in parallel.
1233
1234	=back
1235		1755
1236	=head1 EXAMPLE PROGRAM	1756	=head1 EXAMPLE PROGRAM
1237		1757
1238	The following program uses an I/O watcher to read data from STDIN, a timer	1758	The following program uses an I/O watcher to read data from STDIN, a timer
1239	to display a message once per second, and a condition variable to quit the	1759	to display a message once per second, and a condition variable to quit the
…		…
1433	watcher.	1953	watcher.
1434		1954
1435	=head3 Results	1955	=head3 Results
1436		1956
1437	name watchers bytes create invoke destroy comment	1957	name watchers bytes create invoke destroy comment
1438	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1958	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1439	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1959	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1440	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1960	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1441	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1961	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1442	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1962	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1443	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1963	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1964	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1965	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1444	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1966	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1445	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1967	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1446	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1968	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1447	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1969	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1448		1970
1449	=head3 Discussion	1971	=head3 Discussion
1450		1972
1451	The benchmark does I<not> measure scalability of the event loop very	1973	The benchmark does I<not> measure scalability of the event loop very
1452	well. For example, a select-based event loop (such as the pure perl one)	1974	well. For example, a select-based event loop (such as the pure perl one)
…		…
1477	performance becomes really bad with lots of file descriptors (and few of	1999	performance becomes really bad with lots of file descriptors (and few of
1478	them active), of course, but this was not subject of this benchmark.	2000	them active), of course, but this was not subject of this benchmark.
1479		2001
1480	The C<Event> module has a relatively high setup and callback invocation	2002	The C<Event> module has a relatively high setup and callback invocation
1481	cost, but overall scores in on the third place.	2003	cost, but overall scores in on the third place.
		2004
		2005	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2006	when using its pure perl backend.
1482		2007
1483	C<Glib>'s memory usage is quite a bit higher, but it features a	2008	C<Glib>'s memory usage is quite a bit higher, but it features a
1484	faster callback invocation and overall ends up in the same class as	2009	faster callback invocation and overall ends up in the same class as
1485	C<Event>. However, Glib scales extremely badly, doubling the number of	2010	C<Event>. However, Glib scales extremely badly, doubling the number of
1486	watchers increases the processing time by more than a factor of four,	2011	watchers increases the processing time by more than a factor of four,
…		…
1564	it to another server. This includes deleting the old timeout and creating	2089	it to another server. This includes deleting the old timeout and creating
1565	a new one that moves the timeout into the future.	2090	a new one that moves the timeout into the future.
1566		2091
1567	=head3 Results	2092	=head3 Results
1568		2093
1569	name sockets create request	2094	name sockets create request
1570	EV 20000 69.01 11.16	2095	EV 20000 69.01 11.16
1571	Perl 20000 73.32 35.87	2096	Perl 20000 73.32 35.87
		2097	IOAsync 20000 157.00 98.14 epoll
		2098	IOAsync 20000 159.31 616.06 poll
1572	Event 20000 212.62 257.32	2099	Event 20000 212.62 257.32
1573	Glib 20000 651.16 1896.30	2100	Glib 20000 651.16 1896.30
1574	POE 20000 349.67 12317.24 uses POE::Loop::Event	2101	POE 20000 349.67 12317.24 uses POE::Loop::Event
1575		2102
1576	=head3 Discussion	2103	=head3 Discussion
1577		2104
1578	This benchmark I<does> measure scalability and overall performance of the	2105	This benchmark I<does> measure scalability and overall performance of the
1579	particular event loop.	2106	particular event loop.
…		…
1581	EV is again fastest. Since it is using epoll on my system, the setup time	2108	EV is again fastest. Since it is using epoll on my system, the setup time
1582	is relatively high, though.	2109	is relatively high, though.
1583		2110
1584	Perl surprisingly comes second. It is much faster than the C-based event	2111	Perl surprisingly comes second. It is much faster than the C-based event
1585	loops Event and Glib.	2112	loops Event and Glib.
		2113
		2114	IO::Async performs very well when using its epoll backend, and still quite
		2115	good compared to Glib when using its pure perl backend.
1586		2116
1587	Event suffers from high setup time as well (look at its code and you will	2117	Event suffers from high setup time as well (look at its code and you will
1588	understand why). Callback invocation also has a high overhead compared to	2118	understand why). Callback invocation also has a high overhead compared to
1589	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2119	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1590	uses select or poll in basically all documented configurations.	2120	uses select or poll in basically all documented configurations.
…		…
1653	=item * C-based event loops perform very well with small number of	2183	=item * C-based event loops perform very well with small number of
1654	watchers, as the management overhead dominates.	2184	watchers, as the management overhead dominates.
1655		2185
1656	=back	2186	=back
1657		2187
		2188	=head2 THE IO::Lambda BENCHMARK
		2189
		2190	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2191	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2192	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2193	shouldn't come as a surprise to anybody). As such, the benchmark is
		2194	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2195	very optimal. But how would AnyEvent compare when used without the extra
		2196	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2197
		2198	The benchmark itself creates an echo-server, and then, for 500 times,
		2199	connects to the echo server, sends a line, waits for the reply, and then
		2200	creates the next connection. This is a rather bad benchmark, as it doesn't
		2201	test the efficiency of the framework or much non-blocking I/O, but it is a
		2202	benchmark nevertheless.
		2203
		2204	name runtime
		2205	Lambda/select 0.330 sec
		2206	+ optimized 0.122 sec
		2207	Lambda/AnyEvent 0.327 sec
		2208	+ optimized 0.138 sec
		2209	Raw sockets/select 0.077 sec
		2210	POE/select, components 0.662 sec
		2211	POE/select, raw sockets 0.226 sec
		2212	POE/select, optimized 0.404 sec
		2213
		2214	AnyEvent/select/nb 0.085 sec
		2215	AnyEvent/EV/nb 0.068 sec
		2216	+state machine 0.134 sec
		2217
		2218	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2219	benchmarks actually make blocking connects and use 100% blocking I/O,
		2220	defeating the purpose of an event-based solution. All of the newly
		2221	written AnyEvent benchmarks use 100% non-blocking connects (using
		2222	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2223	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2224	generally require a lot more bookkeeping and event handling than blocking
		2225	connects (which involve a single syscall only).
		2226
		2227	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2228	offers similar expressive power as POE and IO::Lambda, using conventional
		2229	Perl syntax. This means that both the echo server and the client are 100%
		2230	non-blocking, further placing it at a disadvantage.
		2231
		2232	As you can see, the AnyEvent + EV combination even beats the
		2233	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2234	backend easily beats IO::Lambda and POE.
		2235
		2236	And even the 100% non-blocking version written using the high-level (and
		2237	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2238	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2239	in a non-blocking way.
		2240
		2241	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2242	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2243	part of the IO::lambda distribution and were used without any changes.
		2244
		2245
		2246	=head1 SIGNALS
		2247
		2248	AnyEvent currently installs handlers for these signals:
		2249
		2250	=over 4
		2251
		2252	=item SIGCHLD
		2253
		2254	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2255	emulation for event loops that do not support them natively. Also, some
		2256	event loops install a similar handler.
		2257
		2258	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2259	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2260
		2261	=item SIGPIPE
		2262
		2263	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2264	when AnyEvent gets loaded.
		2265
		2266	The rationale for this is that AnyEvent users usually do not really depend
		2267	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2268	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2269	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2270	some random socket.
		2271
		2272	The rationale for installing a no-op handler as opposed to ignoring it is
		2273	that this way, the handler will be restored to defaults on exec.
		2274
		2275	Feel free to install your own handler, or reset it to defaults.
		2276
		2277	=back
		2278
		2279	=cut
		2280
		2281	undef $SIG{CHLD}
		2282	if $SIG{CHLD} eq 'IGNORE';
		2283
		2284	$SIG{PIPE} = sub { }
		2285	unless defined $SIG{PIPE};
		2286
		2287	=head1 RECOMMENDED/OPTIONAL MODULES
		2288
		2289	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2290	it's built-in modules) are required to use it.
		2291
		2292	That does not mean that AnyEvent won't take advantage of some additional
		2293	modules if they are installed.
		2294
		2295	This section epxlains which additional modules will be used, and how they
		2296	affect AnyEvent's operetion.
		2297
		2298	=over 4
		2299
		2300	=item L<Async::Interrupt>
		2301
		2302	This slightly arcane module is used to implement fast signal handling: To
		2303	my knowledge, there is no way to do completely race-free and quick
		2304	signal handling in pure perl. To ensure that signals still get
		2305	delivered, AnyEvent will start an interval timer to wake up perl (and
		2306	catch the signals) with some delay (default is 10 seconds, look for
		2307	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2308
		2309	If this module is available, then it will be used to implement signal
		2310	catching, which means that signals will not be delayed, and the event loop
		2311	will not be interrupted regularly, which is more efficient (And good for
		2312	battery life on laptops).
		2313
		2314	This affects not just the pure-perl event loop, but also other event loops
		2315	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2316
		2317	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2318	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2319	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2320	does nothing for those backends.
		2321
		2322	=item L<EV>
		2323
		2324	This module isn't really "optional", as it is simply one of the backend
		2325	event loops that AnyEvent can use. However, it is simply the best event
		2326	loop available in terms of features, speed and stability: It supports
		2327	the AnyEvent API optimally, implements all the watcher types in XS, does
		2328	automatic timer adjustments even when no monotonic clock is available,
		2329	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2330	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2331	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2332
		2333	=item L<Guard>
		2334
		2335	The guard module, when used, will be used to implement
		2336	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2337	lot less memory), but otherwise doesn't affect guard operation much. It is
		2338	purely used for performance.
		2339
		2340	=item L<JSON> and L<JSON::XS>
		2341
		2342	This module is required when you want to read or write JSON data via
		2343	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2344	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2345
		2346	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2347	installed.
		2348
		2349	=item L<Net::SSLeay>
		2350
		2351	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2352	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2353	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2354
		2355	=item L<Time::HiRes>
		2356
		2357	This module is part of perl since release 5.008. It will be used when the
		2358	chosen event library does not come with a timing source on it's own. The
		2359	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2360	try to use a monotonic clock for timing stability.
		2361
		2362	=back
		2363
1658		2364
1659	=head1 FORK	2365	=head1 FORK
1660		2366
1661	Most event libraries are not fork-safe. The ones who are usually are	2367	Most event libraries are not fork-safe. The ones who are usually are
1662	because they rely on inefficient but fork-safe C<select> or C<poll>	2368	because they rely on inefficient but fork-safe C<select> or C<poll>
1663	calls. Only L<EV> is fully fork-aware.	2369	calls. Only L<EV> is fully fork-aware.
1664		2370
1665	If you have to fork, you must either do so I<before> creating your first	2371	If you have to fork, you must either do so I<before> creating your first
1666	watcher OR you must not use AnyEvent at all in the child.	2372	watcher OR you must not use AnyEvent at all in the child OR you must do
		2373	something completely out of the scope of AnyEvent.
1667		2374
1668		2375
1669	=head1 SECURITY CONSIDERATIONS	2376	=head1 SECURITY CONSIDERATIONS
1670		2377
1671	AnyEvent can be forced to load any event model via	2378	AnyEvent can be forced to load any event model via
…		…
1682		2389
1683	use AnyEvent;	2390	use AnyEvent;
1684		2391
1685	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2392	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1686	be used to probe what backend is used and gain other information (which is	2393	be used to probe what backend is used and gain other information (which is
1687	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2394	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2395	$ENV{PERL_ANYEVENT_STRICT}.
		2396
		2397	Note that AnyEvent will remove I<all> environment variables starting with
		2398	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2399	enabled.
1688		2400
1689		2401
1690	=head1 BUGS	2402	=head1 BUGS
1691		2403
1692	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2404	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1693	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2405	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1694	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2406	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1695	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2407	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1696	pronounced).	2408	pronounced).
1697		2409
1698		2410
1699	=head1 SEE ALSO	2411	=head1 SEE ALSO
1700		2412
…		…
1704	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2416	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1705		2417
1706	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2418	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1707	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2419	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1708	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2420	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1709	L<AnyEvent::Impl::POE>.	2421	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1710		2422
1711	Non-blocking file handles, sockets, TCP clients and	2423	Non-blocking file handles, sockets, TCP clients and
1712	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2424	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1713		2425
1714	Asynchronous DNS: L<AnyEvent::DNS>.	2426	Asynchronous DNS: L<AnyEvent::DNS>.
1715		2427
1716	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2428	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2429	L<Coro::Event>,
1717		2430
1718	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2431	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2432	L<AnyEvent::HTTP>.
1719		2433
1720		2434
1721	=head1 AUTHOR	2435	=head1 AUTHOR
1722		2436
1723	Marc Lehmann <schmorp@schmorp.de>	2437	Marc Lehmann <schmorp@schmorp.de>

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