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Revision 1.18 by root, Sun Dec 10 21:33:33 2006 UTC vs.
Revision 1.231 by root, Wed Jul 8 13:46:46 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	Event, Coro, Glib, Tk, Perl - 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 wether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
		35	$w->send; # wake up current and all future recv's
20	$w->wait; # enters "main loop" till $condvar gets ->broadcast	36	$w->recv; # enters "main loop" till $condvar gets ->send
21	$w->broadcast; # wake up current and all future wait's	37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		39
		40	=head1 INTRODUCTION/TUTORIAL
		41
		42	This manpage is mainly a reference manual. If you are interested
		43	in a tutorial or some gentle introduction, have a look at the
		44	L<AnyEvent::Intro> manpage.
		45
		46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
		47
		48	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
		49	nowadays. So what is different about AnyEvent?
		50
		51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
		52	policy> and AnyEvent is I<small and efficient>.
		53
		54	First and foremost, I<AnyEvent is not an event model> itself, it only
		55	interfaces to whatever event model the main program happens to use, in a
		56	pragmatic way. For event models and certain classes of immortals alike,
		57	the statement "there can only be one" is a bitter reality: In general,
		58	only one event loop can be active at the same time in a process. AnyEvent
		59	cannot change this, but it can hide the differences between those event
		60	loops.
		61
		62	The goal of AnyEvent is to offer module authors the ability to do event
		63	programming (waiting for I/O or timer events) without subscribing to a
		64	religion, a way of living, and most importantly: without forcing your
		65	module users into the same thing by forcing them to use the same event
		66	model you use.
		67
		68	For modules like POE or IO::Async (which is a total misnomer as it is
		69	actually doing all I/O I<synchronously>...), using them in your module is
		70	like joining a cult: After you joined, you are dependent on them and you
		71	cannot use anything else, as they are simply incompatible to everything
		72	that isn't them. What's worse, all the potential users of your
		73	module are I<also> forced to use the same event loop you use.
		74
		75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
		76	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
		77	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
		78	your module uses one of those, every user of your module has to use it,
		79	too. But if your module uses AnyEvent, it works transparently with all
		80	event models it supports (including stuff like IO::Async, as long as those
		81	use one of the supported event loops. It is trivial to add new event loops
		82	to AnyEvent, too, so it is future-proof).
		83
		84	In addition to being free of having to use I<the one and only true event
		85	model>, AnyEvent also is free of bloat and policy: with POE or similar
		86	modules, you get an enormous amount of code and strict rules you have to
		87	follow. AnyEvent, on the other hand, is lean and up to the point, by only
		88	offering the functionality that is necessary, in as thin as a wrapper as
		89	technically possible.
		90
		91	Of course, AnyEvent comes with a big (and fully optional!) toolbox
		92	of useful functionality, such as an asynchronous DNS resolver, 100%
		93	non-blocking connects (even with TLS/SSL, IPv6 and on broken platforms
		94	such as Windows) and lots of real-world knowledge and workarounds for
		95	platform bugs and differences.
		96
		97	Now, if you I<do want> lots of policy (this can arguably be somewhat
		98	useful) and you want to force your users to use the one and only event
		99	model, you should I<not> use this module.
22		100
23	=head1 DESCRIPTION	101	=head1 DESCRIPTION
24		102
25	L<AnyEvent> provides an identical interface to multiple event loops. This	103	L<AnyEvent> provides an identical interface to multiple event loops. This
26	allows module authors to utilise an event loop without forcing module	104	allows module authors to utilise an event loop without forcing module
27	users to use the same event loop (as only a single event loop can coexist	105	users to use the same event loop (as only a single event loop can coexist
28	peacefully at any one time).	106	peacefully at any one time).
29		107
30	The interface itself is vaguely similar but not identical to the Event	108	The interface itself is vaguely similar, but not identical to the L<Event>
31	module.	109	module.
32		110
33	On the first call of any method, the module tries to detect the currently	111	During the first call of any watcher-creation method, the module tries
34	loaded event loop by probing wether any of the following modules is	112	to detect the currently loaded event loop by probing whether one of the
35	loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is	113	following modules is already loaded: L<EV>,
36	used. If none is found, the module tries to load these modules in the	114	L<Event>, L<Glib>, L<AnyEvent::Impl::Perl>, L<Tk>, L<Event::Lib>, L<Qt>,
37	order given. The first one that could be successfully loaded will be	115	L<POE>. The first one found is used. If none are found, the module tries
38	used. If still none could be found, AnyEvent will fall back to a pure-perl	116	to load these modules (excluding Tk, Event::Lib, Qt and POE as the pure perl
39	event loop, which is also not very efficient.	117	adaptor should always succeed) in the order given. The first one that can
		118	be successfully loaded will be used. If, after this, still none could be
		119	found, AnyEvent will fall back to a pure-perl event loop, which is not
		120	very efficient, but should work everywhere.
40		121
41	Because AnyEvent first checks for modules that are already loaded, loading	122	Because AnyEvent first checks for modules that are already loaded, loading
42	an Event model explicitly before first using AnyEvent will likely make	123	an event model explicitly before first using AnyEvent will likely make
43	that model the default. For example:	124	that model the default. For example:
44		125
45	use Tk;	126	use Tk;
46	use AnyEvent;	127	use AnyEvent;
47		128
48	# .. AnyEvent will likely default to Tk	129	# .. AnyEvent will likely default to Tk
49		130
		131	The I<likely> means that, if any module loads another event model and
		132	starts using it, all bets are off. Maybe you should tell their authors to
		133	use AnyEvent so their modules work together with others seamlessly...
		134
50	The pure-perl implementation of AnyEvent is called	135	The pure-perl implementation of AnyEvent is called
51	C<AnyEvent::Impl::Perl>. Like other event modules you can load it	136	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
52	explicitly.	137	explicitly and enjoy the high availability of that event loop :)
53		138
54	=head1 WATCHERS	139	=head1 WATCHERS
55		140
56	AnyEvent has the central concept of a I<watcher>, which is an object that	141	AnyEvent has the central concept of a I<watcher>, which is an object that
57	stores relevant data for each kind of event you are waiting for, such as	142	stores relevant data for each kind of event you are waiting for, such as
58	the callback to call, the filehandle to watch, etc.	143	the callback to call, the file handle to watch, etc.
59		144
60	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
61	creating a watcher it will immediately "watch" for events and invoke	146	creating a watcher it will immediately "watch" for events and invoke the
		147	callback when the event occurs (of course, only when the event model
		148	is in control).
		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
62	the callback. To disable the watcher you have to destroy it (e.g. by	156	To disable the watcher you have to destroy it (e.g. by setting the
63	setting the variable that stores it to C<undef> or otherwise deleting all	157	variable you store it in to C<undef> or otherwise deleting all references
64	references to it).	158	to it).
65		159
66	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
67		161
		162	Many watchers either are used with "recursion" (repeating timers for
		163	example), or need to refer to their watcher object in other ways.
		164
		165	An any way to achieve that is this pattern:
		166
		167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
		168	# you can use $w here, for example to undef it
		169	undef $w;
		170	});
		171
		172	Note that C<my $w; $w => combination. This is necessary because in Perl,
		173	my variables are only visible after the statement in which they are
		174	declared.
		175
68	=head2 IO WATCHERS	176	=head2 I/O WATCHERS
69		177
70	You can create I/O watcher by calling the C<< AnyEvent->io >> method with	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
71	the following mandatory arguments:	179	with the following mandatory key-value pairs as arguments:
72		180
73	C<fh> the Perl I<filehandle> (not filedescriptor) to watch for	181	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
		182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
74	events. C<poll> must be a string that is either C<r> or C<w>, that creates	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
75	a watcher waiting for "r"eadable or "w"ritable events. C<cb> teh callback	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
76	to invoke everytime the filehandle becomes ready.
77		190
78	Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on	191	C<cb> is the callback to invoke each time the file handle becomes ready.
79	a socket you can have one r + one w, not any more (limitation comes from
80	Tk - if you are sure you are not using Tk this limitation is gone).
81		192
82	Filehandles will be kept alive, so as long as the watcher exists, the	193	Although the callback might get passed parameters, their value and
83	filehandle exists, too.	194	presence is undefined and you cannot rely on them. Portable AnyEvent
		195	callbacks cannot use arguments passed to I/O watcher callbacks.
84		196
85	Example:	197	The I/O watcher might use the underlying file descriptor or a copy of it.
		198	You must not close a file handle as long as any watcher is active on the
		199	underlying file descriptor.
86		200
		201	Some event loops issue spurious readyness notifications, so you should
		202	always use non-blocking calls when reading/writing from/to your file
		203	handles.
		204
87	# wait for readability of STDIN, then read a line and disable the watcher	205	Example: wait for readability of STDIN, then read a line and disable the
		206	watcher.
		207
88	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
89	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
90	warn "read: $input\n";	210	warn "read: $input\n";
91	undef $w;	211	undef $w;
92	});	212	});
93		213
94	=head2 TIMER WATCHERS	214	=head2 TIME WATCHERS
95		215
96	You can create a timer watcher by calling the C<< AnyEvent->timer >>	216	You can create a time watcher by calling the C<< AnyEvent->timer >>
97	method with the following mandatory arguments:	217	method with the following mandatory arguments:
98		218
99	C<after> after how many seconds (fractions are supported) should the timer	219	C<after> specifies after how many seconds (fractional values are
100	activate. C<cb> the callback to invoke.	220	supported) the callback should be invoked. C<cb> is the callback to invoke
		221	in that case.
101		222
102	The timer callback will be invoked at most once: if you want a repeating	223	Although the callback might get passed parameters, their value and
103	timer you have to create a new watcher (this is a limitation by both Tk	224	presence is undefined and you cannot rely on them. Portable AnyEvent
104	and Glib).	225	callbacks cannot use arguments passed to time watcher callbacks.
105		226
106	Example:	227	The callback will normally be invoked once only. If you specify another
		228	parameter, C<interval>, as a strictly positive number (> 0), then the
		229	callback will be invoked regularly at that interval (in fractional
		230	seconds) after the first invocation. If C<interval> is specified with a
		231	false value, then it is treated as if it were missing.
107		232
		233	The callback will be rescheduled before invoking the callback, but no
		234	attempt is done to avoid timer drift in most backends, so the interval is
		235	only approximate.
		236
108	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
109	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
110	warn "timeout\n";	240	warn "timeout\n";
111	});	241	});
112		242
113	# to cancel the timer:	243	# to cancel the timer:
114	undef $w	244	undef $w;
115		245
116	=head2 CONDITION WATCHERS	246	Example 2: fire an event after 0.5 seconds, then roughly every second.
117		247
118	Condition watchers can be created by calling the C<< AnyEvent->condvar >>	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
119	method without any arguments.	249	warn "timeout\n";
		250	};
120		251
121	A condition watcher watches for a condition - precisely that the C<<	252	=head3 TIMING ISSUES
122	->broadcast >> method has been called.
123		253
124	The watcher has only two methods:	254	There are two ways to handle timers: based on real time (relative, "fire
		255	in 10 seconds") and based on wallclock time (absolute, "fire at 12
		256	o'clock").
		257
		258	While most event loops expect timers to specified in a relative way, they
		259	use absolute time internally. This makes a difference when your clock
		260	"jumps", for example, when ntp decides to set your clock backwards from
		261	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
		262	fire "after" a second might actually take six years to finally fire.
		263
		264	AnyEvent cannot compensate for this. The only event loop that is conscious
		265	about these issues is L<EV>, which offers both relative (ev_timer, based
		266	on true relative time) and absolute (ev_periodic, based on wallclock time)
		267	timers.
		268
		269	AnyEvent always prefers relative timers, if available, matching the
		270	AnyEvent API.
		271
		272	AnyEvent has two additional methods that return the "current time":
125		273
126	=over 4	274	=over 4
127		275
128	=item $cv->wait	276	=item AnyEvent->time
129		277
130	Wait (blocking if necessary) until the C<< ->broadcast >> method has been	278	This returns the "current wallclock time" as a fractional number of
131	called on c<$cv>, while servicing other watchers normally.	279	seconds since the Epoch (the same thing as C<time> or C<Time::HiRes::time>
		280	return, and the result is guaranteed to be compatible with those).
132		281
133	Not all event models support a blocking wait - some die in that case, so	282	It progresses independently of any event loop processing, i.e. each call
134	if you are using this from a module, never require a blocking wait, but	283	will check the system clock, which usually gets updated frequently.
135	let the caller decide wether the call will block or not (for example,
136	by coupling condition variables with some kind of request results and
137	supporting callbacks so the caller knows that getting the result will not
138	block, while still suppporting blockign waits if the caller so desires).
139		284
140	You can only wait once on a condition - additional calls will return	285	=item AnyEvent->now
141	immediately.
142		286
143	=item $cv->broadcast	287	This also returns the "current wallclock time", but unlike C<time>, above,
		288	this value might change only once per event loop iteration, depending on
		289	the event loop (most return the same time as C<time>, above). This is the
		290	time that AnyEvent's timers get scheduled against.
144		291
145	Flag the condition as ready - a running C<< ->wait >> and all further	292	I<In almost all cases (in all cases if you don't care), this is the
146	calls to C<wait> will return after this method has been called. If nobody	293	function to call when you want to know the current time.>
147	is waiting the broadcast will be remembered..
148		294
149	Example:	295	This function is also often faster then C<< AnyEvent->time >>, and
		296	thus the preferred method if you want some timestamp (for example,
		297	L<AnyEvent::Handle> uses this to update it's activity timeouts).
		298
		299	The rest of this section is only of relevance if you try to be very exact
		300	with your timing, you can skip it without bad conscience.
		301
		302	For a practical example of when these times differ, consider L<Event::Lib>
		303	and L<EV> and the following set-up:
		304
		305	The event loop is running and has just invoked one of your callback at
		306	time=500 (assume no other callbacks delay processing). In your callback,
		307	you wait a second by executing C<sleep 1> (blocking the process for a
		308	second) and then (at time=501) you create a relative timer that fires
		309	after three seconds.
		310
		311	With L<Event::Lib>, C<< AnyEvent->time >> and C<< AnyEvent->now >> will
		312	both return C<501>, because that is the current time, and the timer will
		313	be scheduled to fire at time=504 (C<501> + C<3>).
		314
		315	With L<EV>, C<< AnyEvent->time >> returns C<501> (as that is the current
		316	time), but C<< AnyEvent->now >> returns C<500>, as that is the time the
		317	last event processing phase started. With L<EV>, your timer gets scheduled
		318	to run at time=503 (C<500> + C<3>).
		319
		320	In one sense, L<Event::Lib> is more exact, as it uses the current time
		321	regardless of any delays introduced by event processing. However, most
		322	callbacks do not expect large delays in processing, so this causes a
		323	higher drift (and a lot more system calls to get the current time).
		324
		325	In another sense, L<EV> is more exact, as your timer will be scheduled at
		326	the same time, regardless of how long event processing actually took.
		327
		328	In either case, if you care (and in most cases, you don't), then you
		329	can get whatever behaviour you want with any event loop, by taking the
		330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
		331	account.
		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
		348	=back
		349
		350	=head2 SIGNAL WATCHERS
		351
		352	You can watch for signals using a signal watcher, C<signal> is the signal
		353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
		354	callback to be invoked whenever a signal occurs.
		355
		356	Although the callback might get passed parameters, their value and
		357	presence is undefined and you cannot rely on them. Portable AnyEvent
		358	callbacks cannot use arguments passed to signal watcher callbacks.
		359
		360	Multiple signal occurrences can be clumped together into one callback
		361	invocation, and callback invocation will be synchronous. Synchronous means
		362	that it might take a while until the signal gets handled by the process,
		363	but it is guaranteed not to interrupt any other callbacks.
		364
		365	The main advantage of using these watchers is that you can share a signal
		366	between multiple watchers.
		367
		368	This watcher might use C<%SIG>, so programs overwriting those signals
		369	directly will likely not work correctly.
		370
		371	Example: exit on SIGINT
		372
		373	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
		374
		375	=head2 CHILD PROCESS WATCHERS
		376
		377	You can also watch on a child process exit and catch its exit status.
		378
		379	The child process is specified by the C<pid> argument (if set to C<0>, it
		380	watches for any child process exit). The watcher will triggered only when
		381	the child process has finished and an exit status is available, not on
		382	any trace events (stopped/continued).
		383
		384	The callback will be called with the pid and exit status (as returned by
		385	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		386	callback arguments.
		387
		388	This watcher type works by installing a signal handler for C<SIGCHLD>,
		389	and since it cannot be shared, nothing else should use SIGCHLD or reap
		390	random child processes (waiting for specific child processes, e.g. inside
		391	C<system>, is just fine).
		392
		393	There is a slight catch to child watchers, however: you usually start them
		394	I<after> the child process was created, and this means the process could
		395	have exited already (and no SIGCHLD will be sent anymore).
		396
		397	Not all event models handle this correctly (neither POE nor IO::Async do,
		398	see their AnyEvent::Impl manpages for details), but even for event models
		399	that I<do> handle this correctly, they usually need to be loaded before
		400	the process exits (i.e. before you fork in the first place). AnyEvent's
		401	pure perl event loop handles all cases correctly regardless of when you
		402	start the watcher.
		403
		404	This means you cannot create a child watcher as the very first
		405	thing in an AnyEvent program, you I<have> to create at least one
		406	watcher before you C<fork> the child (alternatively, you can call
		407	C<AnyEvent::detect>).
		408
		409	Example: fork a process and wait for it
		410
		411	my $done = AnyEvent->condvar;
		412
		413	my $pid = fork or exit 5;
		414
		415	my $w = AnyEvent->child (
		416	pid => $pid,
		417	cb => sub {
		418	my ($pid, $status) = @_;
		419	warn "pid $pid exited with status $status";
		420	$done->send;
		421	},
		422	);
		423
		424	# do something else, then wait for process exit
		425	$done->recv;
		426
		427	=head2 IDLE WATCHERS
		428
		429	Sometimes there is a need to do something, but it is not so important
		430	to do it instantly, but only when there is nothing better to do. This
		431	"nothing better to do" is usually defined to be "no other events need
		432	attention by the event loop".
		433
		434	Idle watchers ideally get invoked when the event loop has nothing
		435	better to do, just before it would block the process to wait for new
		436	events. Instead of blocking, the idle watcher is invoked.
		437
		438	Most event loops unfortunately do not really support idle watchers (only
		439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		440	will simply call the callback "from time to time".
		441
		442	Example: read lines from STDIN, but only process them when the
		443	program is otherwise idle:
		444
		445	my @lines; # read data
		446	my $idle_w;
		447	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		448	push @lines, scalar <STDIN>;
		449
		450	# start an idle watcher, if not already done
		451	$idle_w ||= AnyEvent->idle (cb => sub {
		452	# handle only one line, when there are lines left
		453	if (my $line = shift @lines) {
		454	print "handled when idle: $line";
		455	} else {
		456	# otherwise disable the idle watcher again
		457	undef $idle_w;
		458	}
		459	});
		460	});
		461
		462	=head2 CONDITION VARIABLES
		463
		464	If you are familiar with some event loops you will know that all of them
		465	require you to run some blocking "loop", "run" or similar function that
		466	will actively watch for new events and call your callbacks.
		467
		468	AnyEvent is different, it expects somebody else to run the event loop and
		469	will only block when necessary (usually when told by the user).
		470
		471	The instrument to do that is called a "condition variable", so called
		472	because they represent a condition that must become true.
		473
		474	Condition variables can be created by calling the C<< AnyEvent->condvar
		475	>> method, usually without arguments. The only argument pair allowed is
		476
		477	C<cb>, which specifies a callback to be called when the condition variable
		478	becomes true, with the condition variable as the first argument (but not
		479	the results).
		480
		481	After creation, the condition variable is "false" until it becomes "true"
		482	by calling the C<send> method (or calling the condition variable as if it
		483	were a callback, read about the caveats in the description for the C<<
		484	->send >> method).
		485
		486	Condition variables are similar to callbacks, except that you can
		487	optionally wait for them. They can also be called merge points - points
		488	in time where multiple outstanding events have been processed. And yet
		489	another way to call them is transactions - each condition variable can be
		490	used to represent a transaction, which finishes at some point and delivers
		491	a result.
		492
		493	Condition variables are very useful to signal that something has finished,
		494	for example, if you write a module that does asynchronous http requests,
		495	then a condition variable would be the ideal candidate to signal the
		496	availability of results. The user can either act when the callback is
		497	called or can synchronously C<< ->recv >> for the results.
		498
		499	You can also use them to simulate traditional event loops - for example,
		500	you can block your main program until an event occurs - for example, you
		501	could C<< ->recv >> in your main program until the user clicks the Quit
		502	button of your app, which would C<< ->send >> the "quit" event.
		503
		504	Note that condition variables recurse into the event loop - if you have
		505	two pieces of code that call C<< ->recv >> in a round-robin fashion, you
		506	lose. Therefore, condition variables are good to export to your caller, but
		507	you should avoid making a blocking wait yourself, at least in callbacks,
		508	as this asks for trouble.
		509
		510	Condition variables are represented by hash refs in perl, and the keys
		511	used by AnyEvent itself are all named C<_ae_XXX> to make subclassing
		512	easy (it is often useful to build your own transaction class on top of
		513	AnyEvent). To subclass, use C<AnyEvent::CondVar> as base class and call
		514	it's C<new> method in your own C<new> method.
		515
		516	There are two "sides" to a condition variable - the "producer side" which
		517	eventually calls C<< -> send >>, and the "consumer side", which waits
		518	for the send to occur.
		519
		520	Example: wait for a timer.
150		521
151	# wait till the result is ready	522	# wait till the result is ready
152	my $result_ready = AnyEvent->condvar;	523	my $result_ready = AnyEvent->condvar;
153		524
154	# do something such as adding a timer	525	# do something such as adding a timer
155	# or socket watcher the calls $result_ready->broadcast	526	# or socket watcher the calls $result_ready->send
156	# when the "result" is ready.	527	# when the "result" is ready.
		528	# in this case, we simply use a timer:
		529	my $w = AnyEvent->timer (
		530	after => 1,
		531	cb => sub { $result_ready->send },
		532	);
157		533
		534	# this "blocks" (while handling events) till the callback
		535	# calls send
158	$result_ready->wait;	536	$result_ready->recv;
		537
		538	Example: wait for a timer, but take advantage of the fact that
		539	condition variables are also code references.
		540
		541	my $done = AnyEvent->condvar;
		542	my $delay = AnyEvent->timer (after => 5, cb => $done);
		543	$done->recv;
		544
		545	Example: Imagine an API that returns a condvar and doesn't support
		546	callbacks. This is how you make a synchronous call, for example from
		547	the main program:
		548
		549	use AnyEvent::CouchDB;
		550
		551	...
		552
		553	my @info = $couchdb->info->recv;
		554
		555	And this is how you would just ste a callback to be called whenever the
		556	results are available:
		557
		558	$couchdb->info->cb (sub {
		559	my @info = $_[0]->recv;
		560	});
		561
		562	=head3 METHODS FOR PRODUCERS
		563
		564	These methods should only be used by the producing side, i.e. the
		565	code/module that eventually sends the signal. Note that it is also
		566	the producer side which creates the condvar in most cases, but it isn't
		567	uncommon for the consumer to create it as well.
		568
		569	=over 4
		570
		571	=item $cv->send (...)
		572
		573	Flag the condition as ready - a running C<< ->recv >> and all further
		574	calls to C<recv> will (eventually) return after this method has been
		575	called. If nobody is waiting the send will be remembered.
		576
		577	If a callback has been set on the condition variable, it is called
		578	immediately from within send.
		579
		580	Any arguments passed to the C<send> call will be returned by all
		581	future C<< ->recv >> calls.
		582
		583	Condition variables are overloaded so one can call them directly
		584	(as a code reference). Calling them directly is the same as calling
		585	C<send>. Note, however, that many C-based event loops do not handle
		586	overloading, so as tempting as it may be, passing a condition variable
		587	instead of a callback does not work. Both the pure perl and EV loops
		588	support overloading, however, as well as all functions that use perl to
		589	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
		590	example).
		591
		592	=item $cv->croak ($error)
		593
		594	Similar to send, but causes all call's to C<< ->recv >> to invoke
		595	C<Carp::croak> with the given error message/object/scalar.
		596
		597	This can be used to signal any errors to the condition variable
		598	user/consumer.
		599
		600	=item $cv->begin ([group callback])
		601
		602	=item $cv->end
		603
		604	These two methods can be used to combine many transactions/events into
		605	one. For example, a function that pings many hosts in parallel might want
		606	to use a condition variable for the whole process.
		607
		608	Every call to C<< ->begin >> will increment a counter, and every call to
		609	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
		610	>>, the (last) callback passed to C<begin> will be executed. That callback
		611	is I<supposed> to call C<< ->send >>, but that is not required. If no
		612	callback was set, C<send> will be called without any arguments.
		613
		614	You can think of C<< $cv->send >> giving you an OR condition (one call
		615	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		616	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		617
		618	Let's start with a simple example: you have two I/O watchers (for example,
		619	STDOUT and STDERR for a program), and you want to wait for both streams to
		620	close before activating a condvar:
		621
		622	my $cv = AnyEvent->condvar;
		623
		624	$cv->begin; # first watcher
		625	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		626	defined sysread $fh1, my $buf, 4096
		627	or $cv->end;
		628	});
		629
		630	$cv->begin; # second watcher
		631	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		632	defined sysread $fh2, my $buf, 4096
		633	or $cv->end;
		634	});
		635
		636	$cv->recv;
		637
		638	This works because for every event source (EOF on file handle), there is
		639	one call to C<begin>, so the condvar waits for all calls to C<end> before
		640	sending.
		641
		642	The ping example mentioned above is slightly more complicated, as the
		643	there are results to be passwd back, and the number of tasks that are
		644	begung can potentially be zero:
		645
		646	my $cv = AnyEvent->condvar;
		647
		648	my %result;
		649	$cv->begin (sub { $cv->send (\%result) });
		650
		651	for my $host (@list_of_hosts) {
		652	$cv->begin;
		653	ping_host_then_call_callback $host, sub {
		654	$result{$host} = ...;
		655	$cv->end;
		656	};
		657	}
		658
		659	$cv->end;
		660
		661	This code fragment supposedly pings a number of hosts and calls
		662	C<send> after results for all then have have been gathered - in any
		663	order. To achieve this, the code issues a call to C<begin> when it starts
		664	each ping request and calls C<end> when it has received some result for
		665	it. Since C<begin> and C<end> only maintain a counter, the order in which
		666	results arrive is not relevant.
		667
		668	There is an additional bracketing call to C<begin> and C<end> outside the
		669	loop, which serves two important purposes: first, it sets the callback
		670	to be called once the counter reaches C<0>, and second, it ensures that
		671	C<send> is called even when C<no> hosts are being pinged (the loop
		672	doesn't execute once).
		673
		674	This is the general pattern when you "fan out" into multiple (but
		675	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
		676	the callback and ensure C<end> is called at least once, and then, for each
		677	subrequest you start, call C<begin> and for each subrequest you finish,
		678	call C<end>.
159		679
160	=back	680	=back
161		681
162	=head1 GLOBALS	682	=head3 METHODS FOR CONSUMERS
		683
		684	These methods should only be used by the consuming side, i.e. the
		685	code awaits the condition.
		686
		687	=over 4
		688
		689	=item $cv->recv
		690
		691	Wait (blocking if necessary) until the C<< ->send >> or C<< ->croak
		692	>> methods have been called on c<$cv>, while servicing other watchers
		693	normally.
		694
		695	You can only wait once on a condition - additional calls are valid but
		696	will return immediately.
		697
		698	If an error condition has been set by calling C<< ->croak >>, then this
		699	function will call C<croak>.
		700
		701	In list context, all parameters passed to C<send> will be returned,
		702	in scalar context only the first one will be returned.
		703
		704	Not all event models support a blocking wait - some die in that case
		705	(programs might want to do that to stay interactive), so I<if you are
		706	using this from a module, never require a blocking wait>, but let the
		707	caller decide whether the call will block or not (for example, by coupling
		708	condition variables with some kind of request results and supporting
		709	callbacks so the caller knows that getting the result will not block,
		710	while still supporting blocking waits if the caller so desires).
		711
		712	Another reason I<never> to C<< ->recv >> in a module is that you cannot
		713	sensibly have two C<< ->recv >>'s in parallel, as that would require
		714	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
		715	can supply.
		716
		717	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
		718	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
		719	versions and also integrates coroutines into AnyEvent, making blocking
		720	C<< ->recv >> calls perfectly safe as long as they are done from another
		721	coroutine (one that doesn't run the event loop).
		722
		723	You can ensure that C<< -recv >> never blocks by setting a callback and
		724	only calling C<< ->recv >> from within that callback (or at a later
		725	time). This will work even when the event loop does not support blocking
		726	waits otherwise.
		727
		728	=item $bool = $cv->ready
		729
		730	Returns true when the condition is "true", i.e. whether C<send> or
		731	C<croak> have been called.
		732
		733	=item $cb = $cv->cb ($cb->($cv))
		734
		735	This is a mutator function that returns the callback set and optionally
		736	replaces it before doing so.
		737
		738	The callback will be called when the condition becomes "true", i.e. when
		739	C<send> or C<croak> are called, with the only argument being the condition
		740	variable itself. Calling C<recv> inside the callback or at any later time
		741	is guaranteed not to block.
		742
		743	=back
		744
		745	=head1 GLOBAL VARIABLES AND FUNCTIONS
163		746
164	=over 4	747	=over 4
165		748
166	=item $AnyEvent::MODEL	749	=item $AnyEvent::MODEL
167		750
…		…
171	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	754	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
172	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	755	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
173		756
174	The known classes so far are:	757	The known classes so far are:
175		758
176	AnyEvent::Impl::Coro based on Coro::Event, best choise.	759	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
177	AnyEvent::Impl::Event based on Event, also best choice :)	760	AnyEvent::Impl::Event based on Event, second best choice.
		761	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
178	AnyEvent::Impl::Glib based on Glib, second-best choice.	762	AnyEvent::Impl::Glib based on Glib, third-best choice.
179	AnyEvent::Impl::Tk based on Tk, very bad choice.	763	AnyEvent::Impl::Tk based on Tk, very bad choice.
180	AnyEvent::Impl::Perl pure-perl implementation, inefficient.	764	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
		765	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		766	AnyEvent::Impl::POE based on POE, not generic enough for full support.
		767
		768	# warning, support for IO::Async is only partial, as it is too broken
		769	# and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
		770	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
		771
		772	There is no support for WxWidgets, as WxWidgets has no support for
		773	watching file handles. However, you can use WxWidgets through the
		774	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
		775	second, which was considered to be too horrible to even consider for
		776	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
		777	it's adaptor.
		778
		779	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
		780	autodetecting them.
		781
		782	=item AnyEvent::detect
		783
		784	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
		785	if necessary. You should only call this function right before you would
		786	have created an AnyEvent watcher anyway, that is, as late as possible at
		787	runtime.
		788
		789	=item $guard = AnyEvent::post_detect { BLOCK }
		790
		791	Arranges for the code block to be executed as soon as the event model is
		792	autodetected (or immediately if this has already happened).
		793
		794	If called in scalar or list context, then it creates and returns an object
		795	that automatically removes the callback again when it is destroyed. See
		796	L<Coro::BDB> for a case where this is useful.
		797
		798	=item @AnyEvent::post_detect
		799
		800	If there are any code references in this array (you can C<push> to it
		801	before or after loading AnyEvent), then they will called directly after
		802	the event loop has been chosen.
		803
		804	You should check C<$AnyEvent::MODEL> before adding to this array, though:
		805	if it contains a true value then the event loop has already been detected,
		806	and the array will be ignored.
		807
		808	Best use C<AnyEvent::post_detect { BLOCK }> instead.
181		809
182	=back	810	=back
183		811
184	=head1 WHAT TO DO IN A MODULE	812	=head1 WHAT TO DO IN A MODULE
185		813
186	As a module author, you should "use AnyEvent" and call AnyEvent methods	814	As a module author, you should C<use AnyEvent> and call AnyEvent methods
187	freely, but you should not load a specific event module or rely on it.	815	freely, but you should not load a specific event module or rely on it.
188		816
189	Be careful when you create watchers in the module body - Anyevent will	817	Be careful when you create watchers in the module body - AnyEvent will
190	decide which event module to use as soon as the first method is called, so	818	decide which event module to use as soon as the first method is called, so
191	by calling AnyEvent in your module body you force the user of your module	819	by calling AnyEvent in your module body you force the user of your module
192	to load the event module first.	820	to load the event module first.
193		821
		822	Never call C<< ->recv >> on a condition variable unless you I<know> that
		823	the C<< ->send >> method has been called on it already. This is
		824	because it will stall the whole program, and the whole point of using
		825	events is to stay interactive.
		826
		827	It is fine, however, to call C<< ->recv >> when the user of your module
		828	requests it (i.e. if you create a http request object ad have a method
		829	called C<results> that returns the results, it should call C<< ->recv >>
		830	freely, as the user of your module knows what she is doing. always).
		831
194	=head1 WHAT TO DO IN THE MAIN PROGRAM	832	=head1 WHAT TO DO IN THE MAIN PROGRAM
195		833
196	There will always be a single main program - the only place that should	834	There will always be a single main program - the only place that should
197	dictate which event model to use.	835	dictate which event model to use.
198		836
199	If it doesn't care, it can just "use AnyEvent" and use it itself, or not	837	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
200	do anything special and let AnyEvent decide which implementation to chose.	838	do anything special (it does not need to be event-based) and let AnyEvent
		839	decide which implementation to chose if some module relies on it.
201		840
202	If the main program relies on a specific event model (for example, in Gtk2	841	If the main program relies on a specific event model - for example, in
203	programs you have to rely on either Glib or Glib::Event), you should load	842	Gtk2 programs you have to rely on the Glib module - you should load the
204	it before loading AnyEvent or any module that uses it, generally, as early	843	event module before loading AnyEvent or any module that uses it: generally
205	as possible. The reason is that modules might create watchers when they	844	speaking, you should load it as early as possible. The reason is that
206	are loaded, and AnyEvent will decide on the event model to use as soon as	845	modules might create watchers when they are loaded, and AnyEvent will
207	it creates watchers, and it might chose the wrong one unless you load the	846	decide on the event model to use as soon as it creates watchers, and it
208	correct one yourself.	847	might chose the wrong one unless you load the correct one yourself.
209		848
210	You can chose to use a rather inefficient pure-perl implementation by	849	You can chose to use a pure-perl implementation by loading the
211	loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is	850	C<AnyEvent::Impl::Perl> module, which gives you similar behaviour
212	generally better.	851	everywhere, but letting AnyEvent chose the model is generally better.
		852
		853	=head2 MAINLOOP EMULATION
		854
		855	Sometimes (often for short test scripts, or even standalone programs who
		856	only want to use AnyEvent), you do not want to run a specific event loop.
		857
		858	In that case, you can use a condition variable like this:
		859
		860	AnyEvent->condvar->recv;
		861
		862	This has the effect of entering the event loop and looping forever.
		863
		864	Note that usually your program has some exit condition, in which case
		865	it is better to use the "traditional" approach of storing a condition
		866	variable somewhere, waiting for it, and sending it when the program should
		867	exit cleanly.
		868
		869
		870	=head1 OTHER MODULES
		871
		872	The following is a non-exhaustive list of additional modules that use
		873	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
		874	modules and other event loops in the same program. Some of the modules
		875	come with AnyEvent, most are available via CPAN.
		876
		877	=over 4
		878
		879	=item L<AnyEvent::Util>
		880
		881	Contains various utility functions that replace often-used but blocking
		882	functions such as C<inet_aton> by event-/callback-based versions.
		883
		884	=item L<AnyEvent::Socket>
		885
		886	Provides various utility functions for (internet protocol) sockets,
		887	addresses and name resolution. Also functions to create non-blocking tcp
		888	connections or tcp servers, with IPv6 and SRV record support and more.
		889
		890	=item L<AnyEvent::Handle>
		891
		892	Provide read and write buffers, manages watchers for reads and writes,
		893	supports raw and formatted I/O, I/O queued and fully transparent and
		894	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		895
		896	=item L<AnyEvent::DNS>
		897
		898	Provides rich asynchronous DNS resolver capabilities.
		899
		900	=item L<AnyEvent::HTTP>
		901
		902	A simple-to-use HTTP library that is capable of making a lot of concurrent
		903	HTTP requests.
		904
		905	=item L<AnyEvent::HTTPD>
		906
		907	Provides a simple web application server framework.
		908
		909	=item L<AnyEvent::FastPing>
		910
		911	The fastest ping in the west.
		912
		913	=item L<AnyEvent::DBI>
		914
		915	Executes L<DBI> requests asynchronously in a proxy process.
		916
		917	=item L<AnyEvent::AIO>
		918
		919	Truly asynchronous I/O, should be in the toolbox of every event
		920	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		921	together.
		922
		923	=item L<AnyEvent::BDB>
		924
		925	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		926	L<BDB> and AnyEvent together.
		927
		928	=item L<AnyEvent::GPSD>
		929
		930	A non-blocking interface to gpsd, a daemon delivering GPS information.
		931
		932	=item L<AnyEvent::IRC>
		933
		934	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		935
		936	=item L<AnyEvent::XMPP>
		937
		938	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		939	Net::XMPP2>.
		940
		941	=item L<AnyEvent::IGS>
		942
		943	A non-blocking interface to the Internet Go Server protocol (used by
		944	L<App::IGS>).
		945
		946	=item L<Net::FCP>
		947
		948	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
		949	of AnyEvent.
		950
		951	=item L<Event::ExecFlow>
		952
		953	High level API for event-based execution flow control.
		954
		955	=item L<Coro>
		956
		957	Has special support for AnyEvent via L<Coro::AnyEvent>.
		958
		959	=back
213		960
214	=cut	961	=cut
215		962
216	package AnyEvent;	963	package AnyEvent;
217		964
218	no warnings;	965	no warnings;
219	use strict 'vars';	966	use strict qw(vars subs);
		967
220	use Carp;	968	use Carp;
221		969
222	our $VERSION = '2.1';	970	our $VERSION = 4.801;
223	our $MODEL;	971	our $MODEL;
224		972
225	our $AUTOLOAD;	973	our $AUTOLOAD;
226	our @ISA;	974	our @ISA;
227		975
		976	our @REGISTRY;
		977
		978	our $WIN32;
		979
		980	BEGIN {
		981	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
		982	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		983
		984	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		985	if ${^TAINT};
		986	}
		987
228	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	988	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
229		989
230	our @REGISTRY;	990	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
		991
		992	{
		993	my $idx;
		994	$PROTOCOL{$_} = ++$idx
		995	for reverse split /\s*,\s*/,
		996	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
		997	}
231		998
232	my @models = (	999	my @models = (
233	[Coro::Event:: => AnyEvent::Impl::Coro::],	1000	[EV:: => AnyEvent::Impl::EV::],
234	[Event:: => AnyEvent::Impl::Event::],	1001	[Event:: => AnyEvent::Impl::Event::],
235	[Glib:: => AnyEvent::Impl::Glib::],
236	[Tk:: => AnyEvent::Impl::Tk::],
237	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1002	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		1003	# everything below here will not be autoprobed
		1004	# as the pureperl backend should work everywhere
		1005	# and is usually faster
		1006	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1007	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
		1008	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1009	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		1010	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
		1011	[Wx:: => AnyEvent::Impl::POE::],
		1012	[Prima:: => AnyEvent::Impl::POE::],
		1013	# IO::Async is just too broken - we would need workaorunds for its
		1014	# byzantine signal and broken child handling, among others.
		1015	# IO::Async is rather hard to detect, as it doesn't have any
		1016	# obvious default class.
		1017	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1018	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1019	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
238	);	1020	);
239		1021
240	our %method = map +($_ => 1), qw(io timer condvar broadcast wait DESTROY);	1022	our %method = map +($_ => 1),
		1023	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
		1024
		1025	our @post_detect;
		1026
		1027	sub post_detect(&) {
		1028	my ($cb) = @_;
		1029
		1030	if ($MODEL) {
		1031	$cb->();
		1032
		1033	1
		1034	} else {
		1035	push @post_detect, $cb;
		1036
		1037	defined wantarray
		1038	? bless \$cb, "AnyEvent::Util::postdetect"
		1039	: ()
		1040	}
		1041	}
		1042
		1043	sub AnyEvent::Util::postdetect::DESTROY {
		1044	@post_detect = grep $_ != ${$_[0]}, @post_detect;
		1045	}
		1046
		1047	sub detect() {
		1048	unless ($MODEL) {
		1049	no strict 'refs';
		1050	local $SIG{__DIE__};
		1051
		1052	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
		1053	my $model = "AnyEvent::Impl::$1";
		1054	if (eval "require $model") {
		1055	$MODEL = $model;
		1056	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;
		1057	} else {
		1058	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;
		1059	}
		1060	}
		1061
		1062	# check for already loaded models
		1063	unless ($MODEL) {
		1064	for (@REGISTRY, @models) {
		1065	my ($package, $model) = @$_;
		1066	if (${"$package\::VERSION"} > 0) {
		1067	if (eval "require $model") {
		1068	$MODEL = $model;
		1069	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
		1070	last;
		1071	}
		1072	}
		1073	}
		1074
		1075	unless ($MODEL) {
		1076	# try to load a model
		1077
		1078	for (@REGISTRY, @models) {
		1079	my ($package, $model) = @$_;
		1080	if (eval "require $package"
		1081	and ${"$package\::VERSION"} > 0
		1082	and eval "require $model") {
		1083	$MODEL = $model;
		1084	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
		1085	last;
		1086	}
		1087	}
		1088
		1089	$MODEL
		1090	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
		1091	}
		1092	}
		1093
		1094	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1095
		1096	unshift @ISA, $MODEL;
		1097
		1098	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
		1099
		1100	(shift @post_detect)->() while @post_detect;
		1101	}
		1102
		1103	$MODEL
		1104	}
241		1105
242	sub AUTOLOAD {	1106	sub AUTOLOAD {
243	(my $func = $AUTOLOAD) =~ s/.*://;	1107	(my $func = $AUTOLOAD) =~ s/.*://;
244		1108
245	$method{$func}	1109	$method{$func}
246	or croak "$func: not a valid method for AnyEvent objects";	1110	or croak "$func: not a valid method for AnyEvent objects";
247		1111
248	unless ($MODEL) {	1112	detect unless $MODEL;
249	# check for already loaded models
250	for (@REGISTRY, @models) {
251	my ($package, $model) = @$_;
252	if (${"$package\::VERSION"} > 0) {
253	if (eval "require $model") {
254	$MODEL = $model;
255	warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1;
256	last;
257	}
258	}
259	}
260		1113
261	unless ($MODEL) {	1114	my $class = shift;
262	# try to load a model	1115	$class->$func (@_);
		1116	}
263		1117
264	for (@REGISTRY, @models) {	1118	# utility function to dup a filehandle. this is used by many backends
265	my ($package, $model) = @$_;	1119	# to support binding more than one watcher per filehandle (they usually
266	if (eval "require $model") {	1120	# allow only one watcher per fd, so we dup it to get a different one).
267	$MODEL = $model;	1121	sub _dupfh($$;$$) {
268	warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1;	1122	my ($poll, $fh, $r, $w) = @_;
269	last;
270	}
271	}
272		1123
273	$MODEL	1124	# cygwin requires the fh mode to be matching, unix doesn't
274	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk.";	1125	my ($rw, $mode) = $poll eq "r" ? ($r, "<") : ($w, ">");
		1126
		1127	open my $fh2, "$mode&", $fh
		1128	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1129
		1130	# we assume CLOEXEC is already set by perl in all important cases
		1131
		1132	($fh2, $rw)
		1133	}
		1134
		1135	package AnyEvent::Base;
		1136
		1137	# default implementations for many methods
		1138
		1139	BEGIN {
		1140	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1141	*_time = \&Time::HiRes::time;
		1142	# if (eval "use POSIX (); (POSIX::times())...
		1143	} else {
		1144	*_time = sub { time }; # epic fail
		1145	}
		1146	}
		1147
		1148	sub time { _time }
		1149	sub now { _time }
		1150	sub now_update { }
		1151
		1152	# default implementation for ->condvar
		1153
		1154	sub condvar {
		1155	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
		1156	}
		1157
		1158	# default implementation for ->signal
		1159
		1160	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1161
		1162	sub _signal_exec {
		1163	sysread $SIGPIPE_R, my $dummy, 4;
		1164
		1165	while (%SIG_EV) {
		1166	for (keys %SIG_EV) {
		1167	delete $SIG_EV{$_};
		1168	$_->() for values %{ $SIG_CB{$_} || {} };
275	}	1169	}
276	}	1170	}
		1171	}
277		1172
278	@ISA = $MODEL;	1173	sub signal {
		1174	my (undef, %arg) = @_;
279		1175
		1176	unless ($SIGPIPE_R) {
		1177	require Fcntl;
		1178
		1179	if (AnyEvent::WIN32) {
		1180	require AnyEvent::Util;
		1181
		1182	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1183	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1184	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1185	} else {
		1186	pipe $SIGPIPE_R, $SIGPIPE_W;
		1187	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1188	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1189
		1190	# not strictly required, as $^F is normally 2, but let's make sure...
		1191	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1192	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1193	}
		1194
		1195	$SIGPIPE_R
		1196	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1197
		1198	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1199	}
		1200
		1201	my $signal = uc $arg{signal}
		1202	or Carp::croak "required option 'signal' is missing";
		1203
		1204	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1205	$SIG{$signal} ||= sub {
		1206	local $!;
		1207	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1208	undef $SIG_EV{$signal};
		1209	};
		1210
		1211	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1212	}
		1213
		1214	sub AnyEvent::Base::signal::DESTROY {
		1215	my ($signal, $cb) = @{$_[0]};
		1216
		1217	delete $SIG_CB{$signal}{$cb};
		1218
		1219	# delete doesn't work with older perls - they then
		1220	# print weird messages, or just unconditionally exit
		1221	# instead of getting the default action.
		1222	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
		1223	}
		1224
		1225	# default implementation for ->child
		1226
		1227	our %PID_CB;
		1228	our $CHLD_W;
		1229	our $CHLD_DELAY_W;
		1230	our $WNOHANG;
		1231
		1232	sub _sigchld {
		1233	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1234	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),
		1235	(values %{ $PID_CB{0} || {} });
		1236	}
		1237	}
		1238
		1239	sub child {
		1240	my (undef, %arg) = @_;
		1241
		1242	defined (my $pid = $arg{pid} + 0)
		1243	or Carp::croak "required option 'pid' is missing";
		1244
		1245	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
		1246
		1247	$WNOHANG ||= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
		1248
		1249	unless ($CHLD_W) {
		1250	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
		1251	# child could be a zombie already, so make at least one round
		1252	&_sigchld;
		1253	}
		1254
		1255	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
		1256	}
		1257
		1258	sub AnyEvent::Base::child::DESTROY {
		1259	my ($pid, $cb) = @{$_[0]};
		1260
		1261	delete $PID_CB{$pid}{$cb};
		1262	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
		1263
		1264	undef $CHLD_W unless keys %PID_CB;
		1265	}
		1266
		1267	# idle emulation is done by simply using a timer, regardless
		1268	# of whether the process is idle or not, and not letting
		1269	# the callback use more than 50% of the time.
		1270	sub idle {
		1271	my (undef, %arg) = @_;
		1272
		1273	my ($cb, $w, $rcb) = $arg{cb};
		1274
		1275	$rcb = sub {
		1276	if ($cb) {
		1277	$w = _time;
		1278	&$cb;
		1279	$w = _time - $w;
		1280
		1281	# never use more then 50% of the time for the idle watcher,
		1282	# within some limits
		1283	$w = 0.0001 if $w < 0.0001;
		1284	$w = 5 if $w > 5;
		1285
		1286	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1287	} else {
		1288	# clean up...
		1289	undef $w;
		1290	undef $rcb;
		1291	}
		1292	};
		1293
		1294	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1295
		1296	bless \\$cb, "AnyEvent::Base::idle"
		1297	}
		1298
		1299	sub AnyEvent::Base::idle::DESTROY {
		1300	undef $${$_[0]};
		1301	}
		1302
		1303	package AnyEvent::CondVar;
		1304
		1305	our @ISA = AnyEvent::CondVar::Base::;
		1306
		1307	package AnyEvent::CondVar::Base;
		1308
		1309	use overload
		1310	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },
		1311	fallback => 1;
		1312
		1313	sub _send {
		1314	# nop
		1315	}
		1316
		1317	sub send {
280	my $class = shift;	1318	my $cv = shift;
281	$class->$func (@_);	1319	$cv->{_ae_sent} = [@_];
		1320	(delete $cv->{_ae_cb})->($cv) if $cv->{_ae_cb};
		1321	$cv->_send;
282	}	1322	}
		1323
		1324	sub croak {
		1325	$_[0]{_ae_croak} = $_[1];
		1326	$_[0]->send;
		1327	}
		1328
		1329	sub ready {
		1330	$_[0]{_ae_sent}
		1331	}
		1332
		1333	sub _wait {
		1334	AnyEvent->one_event while !$_[0]{_ae_sent};
		1335	}
		1336
		1337	sub recv {
		1338	$_[0]->_wait;
		1339
		1340	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
		1341	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
		1342	}
		1343
		1344	sub cb {
		1345	$_[0]{_ae_cb} = $_[1] if @_ > 1;
		1346	$_[0]{_ae_cb}
		1347	}
		1348
		1349	sub begin {
		1350	++$_[0]{_ae_counter};
		1351	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
		1352	}
		1353
		1354	sub end {
		1355	return if --$_[0]{_ae_counter};
		1356	&{ $_[0]{_ae_end_cb} || sub { $_[0]->send } };
		1357	}
		1358
		1359	# undocumented/compatibility with pre-3.4
		1360	*broadcast = \&send;
		1361	*wait = \&_wait;
		1362
		1363	=head1 ERROR AND EXCEPTION HANDLING
		1364
		1365	In general, AnyEvent does not do any error handling - it relies on the
		1366	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1367	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1368	checking of all AnyEvent methods, however, which is highly useful during
		1369	development.
		1370
		1371	As for exception handling (i.e. runtime errors and exceptions thrown while
		1372	executing a callback), this is not only highly event-loop specific, but
		1373	also not in any way wrapped by this module, as this is the job of the main
		1374	program.
		1375
		1376	The pure perl event loop simply re-throws the exception (usually
		1377	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1378	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1379	so on.
		1380
		1381	=head1 ENVIRONMENT VARIABLES
		1382
		1383	The following environment variables are used by this module or its
		1384	submodules.
		1385
		1386	Note that AnyEvent will remove I<all> environment variables starting with
		1387	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1388	enabled.
		1389
		1390	=over 4
		1391
		1392	=item C<PERL_ANYEVENT_VERBOSE>
		1393
		1394	By default, AnyEvent will be completely silent except in fatal
		1395	conditions. You can set this environment variable to make AnyEvent more
		1396	talkative.
		1397
		1398	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1399	conditions, such as not being able to load the event model specified by
		1400	C<PERL_ANYEVENT_MODEL>.
		1401
		1402	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1403	model it chooses.
		1404
		1405	=item C<PERL_ANYEVENT_STRICT>
		1406
		1407	AnyEvent does not do much argument checking by default, as thorough
		1408	argument checking is very costly. Setting this variable to a true value
		1409	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1410	check the arguments passed to most method calls. If it finds any problems,
		1411	it will croak.
		1412
		1413	In other words, enables "strict" mode.
		1414
		1415	Unlike C<use strict>, it is definitely recommended to keep it off in
		1416	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1417	developing programs can be very useful, however.
		1418
		1419	=item C<PERL_ANYEVENT_MODEL>
		1420
		1421	This can be used to specify the event model to be used by AnyEvent, before
		1422	auto detection and -probing kicks in. It must be a string consisting
		1423	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1424	and the resulting module name is loaded and if the load was successful,
		1425	used as event model. If it fails to load AnyEvent will proceed with
		1426	auto detection and -probing.
		1427
		1428	This functionality might change in future versions.
		1429
		1430	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1431	could start your program like this:
		1432
		1433	PERL_ANYEVENT_MODEL=Perl perl ...
		1434
		1435	=item C<PERL_ANYEVENT_PROTOCOLS>
		1436
		1437	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1438	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1439	of auto probing).
		1440
		1441	Must be set to a comma-separated list of protocols or address families,
		1442	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1443	used, and preference will be given to protocols mentioned earlier in the
		1444	list.
		1445
		1446	This variable can effectively be used for denial-of-service attacks
		1447	against local programs (e.g. when setuid), although the impact is likely
		1448	small, as the program has to handle conenction and other failures anyways.
		1449
		1450	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1451	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1452	- only support IPv4, never try to resolve or contact IPv6
		1453	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1454	IPv6, but prefer IPv6 over IPv4.
		1455
		1456	=item C<PERL_ANYEVENT_EDNS0>
		1457
		1458	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1459	for DNS. This extension is generally useful to reduce DNS traffic, but
		1460	some (broken) firewalls drop such DNS packets, which is why it is off by
		1461	default.
		1462
		1463	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1464	EDNS0 in its DNS requests.
		1465
		1466	=item C<PERL_ANYEVENT_MAX_FORKS>
		1467
		1468	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1469	will create in parallel.
		1470
		1471	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1472
		1473	The default value for the C<max_outstanding> parameter for the default DNS
		1474	resolver - this is the maximum number of parallel DNS requests that are
		1475	sent to the DNS server.
		1476
		1477	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1478
		1479	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1480	configuration) in the default resolver. When set to the empty string, no
		1481	default config will be used.
		1482
		1483	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1484
		1485	When neither C<ca_file> nor C<ca_path> was specified during
		1486	L<AnyEvent::TLS> context creation, and either of these environment
		1487	variables exist, they will be used to specify CA certificate locations
		1488	instead of a system-dependent default.
		1489
		1490	=back
283		1491
284	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1492	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
		1493
		1494	This is an advanced topic that you do not normally need to use AnyEvent in
		1495	a module. This section is only of use to event loop authors who want to
		1496	provide AnyEvent compatibility.
285		1497
286	If you need to support another event library which isn't directly	1498	If you need to support another event library which isn't directly
287	supported by AnyEvent, you can supply your own interface to it by	1499	supported by AnyEvent, you can supply your own interface to it by
288	pushing, before the first watcher gets created, the package name of	1500	pushing, before the first watcher gets created, the package name of
289	the event module and the package name of the interface to use onto	1501	the event module and the package name of the interface to use onto
290	C<@AnyEvent::REGISTRY>. You can do that before and even without loading	1502	C<@AnyEvent::REGISTRY>. You can do that before and even without loading
291	AnyEvent.	1503	AnyEvent, so it is reasonably cheap.
292		1504
293	Example:	1505	Example:
294		1506
295	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];	1507	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
296		1508
297	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>	1509	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
298	package/class when it finds the C<urxvt> package/module is loaded. When	1510	package/class when it finds the C<urxvt> package/module is already loaded.
		1511
299	AnyEvent is loaded and asked to find a suitable event model, it will	1512	When AnyEvent is loaded and asked to find a suitable event model, it
300	first check for the presence of urxvt.	1513	will first check for the presence of urxvt by trying to C<use> the
		1514	C<urxvt::anyevent> module.
301		1515
302	The class should prove implementations for all watcher types (see	1516	The class should provide implementations for all watcher types. See
303	L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib>	1517	L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
304	(Source code) and so on for actual examples, use C<perldoc -m	1518	and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to
305	AnyEvent::Impl::Glib> to see the sources).	1519	see the sources.
306		1520
		1521	If you don't provide C<signal> and C<child> watchers than AnyEvent will
		1522	provide suitable (hopefully) replacements.
		1523
307	The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)	1524	The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
308	uses the above line as-is. An interface isn't included in AnyEvent	1525	terminal emulator uses the above line as-is. An interface isn't included
309	because it doesn't make sense outside the embedded interpreter inside	1526	in AnyEvent because it doesn't make sense outside the embedded interpreter
310	I<rxvt-unicode>, and it is updated and maintained as part of the	1527	inside I<rxvt-unicode>, and it is updated and maintained as part of the
311	I<rxvt-unicode> distribution.	1528	I<rxvt-unicode> distribution.
312		1529
313	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1530	I<rxvt-unicode> also cheats a bit by not providing blocking access to
314	condition variables: code blocking while waiting for a condition will	1531	condition variables: code blocking while waiting for a condition will
315	C<die>. This still works with most modules/usages, and blocking calls must	1532	C<die>. This still works with most modules/usages, and blocking calls must
316	not be in an interactive appliation, so it makes sense.	1533	not be done in an interactive application, so it makes sense.
317		1534
318	=head1 ENVIRONMENT VARIABLES
319
320	The following environment variables are used by this module:
321
322	C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event
323	model gets used.
324
325	=head1 EXAMPLE	1535	=head1 EXAMPLE PROGRAM
326		1536
327	The following program uses an io watcher to read data from stdin, a timer	1537	The following program uses an I/O watcher to read data from STDIN, a timer
328	to display a message once per second, and a condvar to exit the program	1538	to display a message once per second, and a condition variable to quit the
329	when the user enters quit:	1539	program when the user enters quit:
330		1540
331	use AnyEvent;	1541	use AnyEvent;
332		1542
333	my $cv = AnyEvent->condvar;	1543	my $cv = AnyEvent->condvar;
334		1544
335	my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	1545	my $io_watcher = AnyEvent->io (
		1546	fh => \*STDIN,
		1547	poll => 'r',
		1548	cb => sub {
336	warn "io event <$_[0]>\n"; # will always output <r>	1549	warn "io event <$_[0]>\n"; # will always output <r>
337	chomp (my $input = <STDIN>); # read a line	1550	chomp (my $input = <STDIN>); # read a line
338	warn "read: $input\n"; # output what has been read	1551	warn "read: $input\n"; # output what has been read
339	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	1552	$cv->send if $input =~ /^q/i; # quit program if /^q/i
		1553	},
340	});	1554	);
341		1555
342	my $time_watcher; # can only be used once	1556	my $time_watcher; # can only be used once
343		1557
344	sub new_timer {	1558	sub new_timer {
345	$timer = AnyEvent->timer (after => 1, cb => sub {	1559	$timer = AnyEvent->timer (after => 1, cb => sub {
…		…
348	});	1562	});
349	}	1563	}
350		1564
351	new_timer; # create first timer	1565	new_timer; # create first timer
352		1566
353	$cv->wait; # wait until user enters /^q/i	1567	$cv->recv; # wait until user enters /^q/i
354		1568
355	=head1 REAL-WORLD EXAMPLE	1569	=head1 REAL-WORLD EXAMPLE
356		1570
357	Consider the L<Net::FCP> module. It features (among others) the following	1571	Consider the L<Net::FCP> module. It features (among others) the following
358	API calls, which are to freenet what HTTP GET requests are to http:	1572	API calls, which are to freenet what HTTP GET requests are to http:
…		…
408	syswrite $txn->{fh}, $txn->{request}	1622	syswrite $txn->{fh}, $txn->{request}
409	or die "connection or write error";	1623	or die "connection or write error";
410	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });	1624	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
411		1625
412	Again, C<fh_ready_r> waits till all data has arrived, and then stores the	1626	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
413	result and signals any possible waiters that the request ahs finished:	1627	result and signals any possible waiters that the request has finished:
414		1628
415	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	1629	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
416		1630
417	if (end-of-file or data complete) {	1631	if (end-of-file or data complete) {
418	$txn->{result} = $txn->{buf};	1632	$txn->{result} = $txn->{buf};
419	$txn->{finished}->broadcast;	1633	$txn->{finished}->send;
420	$txb->{cb}->($txn) of $txn->{cb}; # also call callback	1634	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
421	}	1635	}
422		1636
423	The C<result> method, finally, just waits for the finished signal (if the	1637	The C<result> method, finally, just waits for the finished signal (if the
424	request was already finished, it doesn't wait, of course, and returns the	1638	request was already finished, it doesn't wait, of course, and returns the
425	data:	1639	data:
426		1640
427	$txn->{finished}->wait;	1641	$txn->{finished}->recv;
428	return $txn->{result};	1642	return $txn->{result};
429		1643
430	The actual code goes further and collects all errors (C<die>s, exceptions)	1644	The actual code goes further and collects all errors (C<die>s, exceptions)
431	that occured during request processing. The C<result> method detects	1645	that occurred during request processing. The C<result> method detects
432	wether an exception as thrown (it is stored inside the $txn object)	1646	whether an exception as thrown (it is stored inside the $txn object)
433	and just throws the exception, which means connection errors and other	1647	and just throws the exception, which means connection errors and other
434	problems get reported tot he code that tries to use the result, not in a	1648	problems get reported tot he code that tries to use the result, not in a
435	random callback.	1649	random callback.
436		1650
437	All of this enables the following usage styles:	1651	All of this enables the following usage styles:
438		1652
439	1. Blocking:	1653	1. Blocking:
440		1654
441	my $data = $fcp->client_get ($url);	1655	my $data = $fcp->client_get ($url);
442		1656
443	2. Blocking, but parallelizing:	1657	2. Blocking, but running in parallel:
444		1658
445	my @datas = map $_->result,	1659	my @datas = map $_->result,
446	map $fcp->txn_client_get ($_),	1660	map $fcp->txn_client_get ($_),
447	@urls;	1661	@urls;
448		1662
449	Both blocking examples work without the module user having to know	1663	Both blocking examples work without the module user having to know
450	anything about events.	1664	anything about events.
451		1665
452	3a. Event-based in a main program, using any support Event module:	1666	3a. Event-based in a main program, using any supported event module:
453		1667
454	use Event;	1668	use EV;
455		1669
456	$fcp->txn_client_get ($url)->cb (sub {	1670	$fcp->txn_client_get ($url)->cb (sub {
457	my $txn = shift;	1671	my $txn = shift;
458	my $data = $txn->result;	1672	my $data = $txn->result;
459	...	1673	...
460	});	1674	});
461		1675
462	Event::loop;	1676	EV::loop;
463		1677
464	3b. The module user could use AnyEvent, too:	1678	3b. The module user could use AnyEvent, too:
465		1679
466	use AnyEvent;	1680	use AnyEvent;
467		1681
468	my $quit = AnyEvent->condvar;	1682	my $quit = AnyEvent->condvar;
469		1683
470	$fcp->txn_client_get ($url)->cb (sub {	1684	$fcp->txn_client_get ($url)->cb (sub {
471	...	1685	...
472	$quit->broadcast;	1686	$quit->send;
473	});	1687	});
474		1688
475	$quit->wait;	1689	$quit->recv;
		1690
		1691
		1692	=head1 BENCHMARKS
		1693
		1694	To give you an idea of the performance and overheads that AnyEvent adds
		1695	over the event loops themselves and to give you an impression of the speed
		1696	of various event loops I prepared some benchmarks.
		1697
		1698	=head2 BENCHMARKING ANYEVENT OVERHEAD
		1699
		1700	Here is a benchmark of various supported event models used natively and
		1701	through AnyEvent. The benchmark creates a lot of timers (with a zero
		1702	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
		1703	which it is), lets them fire exactly once and destroys them again.
		1704
		1705	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
		1706	distribution.
		1707
		1708	=head3 Explanation of the columns
		1709
		1710	I<watcher> is the number of event watchers created/destroyed. Since
		1711	different event models feature vastly different performances, each event
		1712	loop was given a number of watchers so that overall runtime is acceptable
		1713	and similar between tested event loop (and keep them from crashing): Glib
		1714	would probably take thousands of years if asked to process the same number
		1715	of watchers as EV in this benchmark.
		1716
		1717	I<bytes> is the number of bytes (as measured by the resident set size,
		1718	RSS) consumed by each watcher. This method of measuring captures both C
		1719	and Perl-based overheads.
		1720
		1721	I<create> is the time, in microseconds (millionths of seconds), that it
		1722	takes to create a single watcher. The callback is a closure shared between
		1723	all watchers, to avoid adding memory overhead. That means closure creation
		1724	and memory usage is not included in the figures.
		1725
		1726	I<invoke> is the time, in microseconds, used to invoke a simple
		1727	callback. The callback simply counts down a Perl variable and after it was
		1728	invoked "watcher" times, it would C<< ->send >> a condvar once to
		1729	signal the end of this phase.
		1730
		1731	I<destroy> is the time, in microseconds, that it takes to destroy a single
		1732	watcher.
		1733
		1734	=head3 Results
		1735
		1736	name watchers bytes create invoke destroy comment
		1737	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
		1738	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
		1739	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
		1740	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
		1741	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
		1742	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1743	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1744	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
		1745	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
		1746	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
		1747	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
		1748	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
		1749
		1750	=head3 Discussion
		1751
		1752	The benchmark does I<not> measure scalability of the event loop very
		1753	well. For example, a select-based event loop (such as the pure perl one)
		1754	can never compete with an event loop that uses epoll when the number of
		1755	file descriptors grows high. In this benchmark, all events become ready at
		1756	the same time, so select/poll-based implementations get an unnatural speed
		1757	boost.
		1758
		1759	Also, note that the number of watchers usually has a nonlinear effect on
		1760	overall speed, that is, creating twice as many watchers doesn't take twice
		1761	the time - usually it takes longer. This puts event loops tested with a
		1762	higher number of watchers at a disadvantage.
		1763
		1764	To put the range of results into perspective, consider that on the
		1765	benchmark machine, handling an event takes roughly 1600 CPU cycles with
		1766	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
		1767	cycles with POE.
		1768
		1769	C<EV> is the sole leader regarding speed and memory use, which are both
		1770	maximal/minimal, respectively. Even when going through AnyEvent, it uses
		1771	far less memory than any other event loop and is still faster than Event
		1772	natively.
		1773
		1774	The pure perl implementation is hit in a few sweet spots (both the
		1775	constant timeout and the use of a single fd hit optimisations in the perl
		1776	interpreter and the backend itself). Nevertheless this shows that it
		1777	adds very little overhead in itself. Like any select-based backend its
		1778	performance becomes really bad with lots of file descriptors (and few of
		1779	them active), of course, but this was not subject of this benchmark.
		1780
		1781	The C<Event> module has a relatively high setup and callback invocation
		1782	cost, but overall scores in on the third place.
		1783
		1784	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1785	when using its pure perl backend.
		1786
		1787	C<Glib>'s memory usage is quite a bit higher, but it features a
		1788	faster callback invocation and overall ends up in the same class as
		1789	C<Event>. However, Glib scales extremely badly, doubling the number of
		1790	watchers increases the processing time by more than a factor of four,
		1791	making it completely unusable when using larger numbers of watchers
		1792	(note that only a single file descriptor was used in the benchmark, so
		1793	inefficiencies of C<poll> do not account for this).
		1794
		1795	The C<Tk> adaptor works relatively well. The fact that it crashes with
		1796	more than 2000 watchers is a big setback, however, as correctness takes
		1797	precedence over speed. Nevertheless, its performance is surprising, as the
		1798	file descriptor is dup()ed for each watcher. This shows that the dup()
		1799	employed by some adaptors is not a big performance issue (it does incur a
		1800	hidden memory cost inside the kernel which is not reflected in the figures
		1801	above).
		1802
		1803	C<POE>, regardless of underlying event loop (whether using its pure perl
		1804	select-based backend or the Event module, the POE-EV backend couldn't
		1805	be tested because it wasn't working) shows abysmal performance and
		1806	memory usage with AnyEvent: Watchers use almost 30 times as much memory
		1807	as EV watchers, and 10 times as much memory as Event (the high memory
		1808	requirements are caused by requiring a session for each watcher). Watcher
		1809	invocation speed is almost 900 times slower than with AnyEvent's pure perl
		1810	implementation.
		1811
		1812	The design of the POE adaptor class in AnyEvent can not really account
		1813	for the performance issues, though, as session creation overhead is
		1814	small compared to execution of the state machine, which is coded pretty
		1815	optimally within L<AnyEvent::Impl::POE> (and while everybody agrees that
		1816	using multiple sessions is not a good approach, especially regarding
		1817	memory usage, even the author of POE could not come up with a faster
		1818	design).
		1819
		1820	=head3 Summary
		1821
		1822	=over 4
		1823
		1824	=item * Using EV through AnyEvent is faster than any other event loop
		1825	(even when used without AnyEvent), but most event loops have acceptable
		1826	performance with or without AnyEvent.
		1827
		1828	=item * The overhead AnyEvent adds is usually much smaller than the overhead of
		1829	the actual event loop, only with extremely fast event loops such as EV
		1830	adds AnyEvent significant overhead.
		1831
		1832	=item * You should avoid POE like the plague if you want performance or
		1833	reasonable memory usage.
		1834
		1835	=back
		1836
		1837	=head2 BENCHMARKING THE LARGE SERVER CASE
		1838
		1839	This benchmark actually benchmarks the event loop itself. It works by
		1840	creating a number of "servers": each server consists of a socket pair, a
		1841	timeout watcher that gets reset on activity (but never fires), and an I/O
		1842	watcher waiting for input on one side of the socket. Each time the socket
		1843	watcher reads a byte it will write that byte to a random other "server".
		1844
		1845	The effect is that there will be a lot of I/O watchers, only part of which
		1846	are active at any one point (so there is a constant number of active
		1847	fds for each loop iteration, but which fds these are is random). The
		1848	timeout is reset each time something is read because that reflects how
		1849	most timeouts work (and puts extra pressure on the event loops).
		1850
		1851	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
		1852	(1%) are active. This mirrors the activity of large servers with many
		1853	connections, most of which are idle at any one point in time.
		1854
		1855	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
		1856	distribution.
		1857
		1858	=head3 Explanation of the columns
		1859
		1860	I<sockets> is the number of sockets, and twice the number of "servers" (as
		1861	each server has a read and write socket end).
		1862
		1863	I<create> is the time it takes to create a socket pair (which is
		1864	nontrivial) and two watchers: an I/O watcher and a timeout watcher.
		1865
		1866	I<request>, the most important value, is the time it takes to handle a
		1867	single "request", that is, reading the token from the pipe and forwarding
		1868	it to another server. This includes deleting the old timeout and creating
		1869	a new one that moves the timeout into the future.
		1870
		1871	=head3 Results
		1872
		1873	name sockets create request
		1874	EV 20000 69.01 11.16
		1875	Perl 20000 73.32 35.87
		1876	IOAsync 20000 157.00 98.14 epoll
		1877	IOAsync 20000 159.31 616.06 poll
		1878	Event 20000 212.62 257.32
		1879	Glib 20000 651.16 1896.30
		1880	POE 20000 349.67 12317.24 uses POE::Loop::Event
		1881
		1882	=head3 Discussion
		1883
		1884	This benchmark I<does> measure scalability and overall performance of the
		1885	particular event loop.
		1886
		1887	EV is again fastest. Since it is using epoll on my system, the setup time
		1888	is relatively high, though.
		1889
		1890	Perl surprisingly comes second. It is much faster than the C-based event
		1891	loops Event and Glib.
		1892
		1893	IO::Async performs very well when using its epoll backend, and still quite
		1894	good compared to Glib when using its pure perl backend.
		1895
		1896	Event suffers from high setup time as well (look at its code and you will
		1897	understand why). Callback invocation also has a high overhead compared to
		1898	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
		1899	uses select or poll in basically all documented configurations.
		1900
		1901	Glib is hit hard by its quadratic behaviour w.r.t. many watchers. It
		1902	clearly fails to perform with many filehandles or in busy servers.
		1903
		1904	POE is still completely out of the picture, taking over 1000 times as long
		1905	as EV, and over 100 times as long as the Perl implementation, even though
		1906	it uses a C-based event loop in this case.
		1907
		1908	=head3 Summary
		1909
		1910	=over 4
		1911
		1912	=item * The pure perl implementation performs extremely well.
		1913
		1914	=item * Avoid Glib or POE in large projects where performance matters.
		1915
		1916	=back
		1917
		1918	=head2 BENCHMARKING SMALL SERVERS
		1919
		1920	While event loops should scale (and select-based ones do not...) even to
		1921	large servers, most programs we (or I :) actually write have only a few
		1922	I/O watchers.
		1923
		1924	In this benchmark, I use the same benchmark program as in the large server
		1925	case, but it uses only eight "servers", of which three are active at any
		1926	one time. This should reflect performance for a small server relatively
		1927	well.
		1928
		1929	The columns are identical to the previous table.
		1930
		1931	=head3 Results
		1932
		1933	name sockets create request
		1934	EV 16 20.00 6.54
		1935	Perl 16 25.75 12.62
		1936	Event 16 81.27 35.86
		1937	Glib 16 32.63 15.48
		1938	POE 16 261.87 276.28 uses POE::Loop::Event
		1939
		1940	=head3 Discussion
		1941
		1942	The benchmark tries to test the performance of a typical small
		1943	server. While knowing how various event loops perform is interesting, keep
		1944	in mind that their overhead in this case is usually not as important, due
		1945	to the small absolute number of watchers (that is, you need efficiency and
		1946	speed most when you have lots of watchers, not when you only have a few of
		1947	them).
		1948
		1949	EV is again fastest.
		1950
		1951	Perl again comes second. It is noticeably faster than the C-based event
		1952	loops Event and Glib, although the difference is too small to really
		1953	matter.
		1954
		1955	POE also performs much better in this case, but is is still far behind the
		1956	others.
		1957
		1958	=head3 Summary
		1959
		1960	=over 4
		1961
		1962	=item * C-based event loops perform very well with small number of
		1963	watchers, as the management overhead dominates.
		1964
		1965	=back
		1966
		1967	=head2 THE IO::Lambda BENCHMARK
		1968
		1969	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1970	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1971	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1972	shouldn't come as a surprise to anybody). As such, the benchmark is
		1973	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		1974	very optimal. But how would AnyEvent compare when used without the extra
		1975	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1976
		1977	The benchmark itself creates an echo-server, and then, for 500 times,
		1978	connects to the echo server, sends a line, waits for the reply, and then
		1979	creates the next connection. This is a rather bad benchmark, as it doesn't
		1980	test the efficiency of the framework or much non-blocking I/O, but it is a
		1981	benchmark nevertheless.
		1982
		1983	name runtime
		1984	Lambda/select 0.330 sec
		1985	+ optimized 0.122 sec
		1986	Lambda/AnyEvent 0.327 sec
		1987	+ optimized 0.138 sec
		1988	Raw sockets/select 0.077 sec
		1989	POE/select, components 0.662 sec
		1990	POE/select, raw sockets 0.226 sec
		1991	POE/select, optimized 0.404 sec
		1992
		1993	AnyEvent/select/nb 0.085 sec
		1994	AnyEvent/EV/nb 0.068 sec
		1995	+state machine 0.134 sec
		1996
		1997	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		1998	benchmarks actually make blocking connects and use 100% blocking I/O,
		1999	defeating the purpose of an event-based solution. All of the newly
		2000	written AnyEvent benchmarks use 100% non-blocking connects (using
		2001	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2002	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2003	generally require a lot more bookkeeping and event handling than blocking
		2004	connects (which involve a single syscall only).
		2005
		2006	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2007	offers similar expressive power as POE and IO::Lambda, using conventional
		2008	Perl syntax. This means that both the echo server and the client are 100%
		2009	non-blocking, further placing it at a disadvantage.
		2010
		2011	As you can see, the AnyEvent + EV combination even beats the
		2012	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2013	backend easily beats IO::Lambda and POE.
		2014
		2015	And even the 100% non-blocking version written using the high-level (and
		2016	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2017	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2018	in a non-blocking way.
		2019
		2020	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2021	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2022	part of the IO::lambda distribution and were used without any changes.
		2023
		2024
		2025	=head1 SIGNALS
		2026
		2027	AnyEvent currently installs handlers for these signals:
		2028
		2029	=over 4
		2030
		2031	=item SIGCHLD
		2032
		2033	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2034	emulation for event loops that do not support them natively. Also, some
		2035	event loops install a similar handler.
		2036
		2037	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		2038	reset it to default, to avoid losing child exit statuses.
		2039
		2040	=item SIGPIPE
		2041
		2042	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2043	when AnyEvent gets loaded.
		2044
		2045	The rationale for this is that AnyEvent users usually do not really depend
		2046	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2047	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2048	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2049	some random socket.
		2050
		2051	The rationale for installing a no-op handler as opposed to ignoring it is
		2052	that this way, the handler will be restored to defaults on exec.
		2053
		2054	Feel free to install your own handler, or reset it to defaults.
		2055
		2056	=back
		2057
		2058	=cut
		2059
		2060	undef $SIG{CHLD}
		2061	if $SIG{CHLD} eq 'IGNORE';
		2062
		2063	$SIG{PIPE} = sub { }
		2064	unless defined $SIG{PIPE};
		2065
		2066	=head1 FORK
		2067
		2068	Most event libraries are not fork-safe. The ones who are usually are
		2069	because they rely on inefficient but fork-safe C<select> or C<poll>
		2070	calls. Only L<EV> is fully fork-aware.
		2071
		2072	If you have to fork, you must either do so I<before> creating your first
		2073	watcher OR you must not use AnyEvent at all in the child.
		2074
		2075
		2076	=head1 SECURITY CONSIDERATIONS
		2077
		2078	AnyEvent can be forced to load any event model via
		2079	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
		2080	execute arbitrary code or directly gain access, it can easily be used to
		2081	make the program hang or malfunction in subtle ways, as AnyEvent watchers
		2082	will not be active when the program uses a different event model than
		2083	specified in the variable.
		2084
		2085	You can make AnyEvent completely ignore this variable by deleting it
		2086	before the first watcher gets created, e.g. with a C<BEGIN> block:
		2087
		2088	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
		2089
		2090	use AnyEvent;
		2091
		2092	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
		2093	be used to probe what backend is used and gain other information (which is
		2094	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2095	$ENV{PERL_ANYEVENT_STRICT}.
		2096
		2097	Note that AnyEvent will remove I<all> environment variables starting with
		2098	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2099	enabled.
		2100
		2101
		2102	=head1 BUGS
		2103
		2104	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2105	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2106	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2107	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2108	pronounced).
		2109
476		2110
477	=head1 SEE ALSO	2111	=head1 SEE ALSO
478		2112
479	Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>.	2113	Utility functions: L<AnyEvent::Util>.
480		2114
481	Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>.	2115	Event modules: L<EV>, L<EV::Glib>, L<Glib::EV>, L<Event>, L<Glib::Event>,
		2116	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
482		2117
483	Nontrivial usage example: L<Net::FCP>.	2118	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
		2119	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
		2120	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
		2121	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
484		2122
485	=head1	2123	Non-blocking file handles, sockets, TCP clients and
		2124	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
		2125
		2126	Asynchronous DNS: L<AnyEvent::DNS>.
		2127
		2128	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2129	L<Coro::Event>,
		2130
		2131	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2132	L<AnyEvent::HTTP>.
		2133
		2134
		2135	=head1 AUTHOR
		2136
		2137	Marc Lehmann <schmorp@schmorp.de>
		2138	http://home.schmorp.de/
486		2139
487	=cut	2140	=cut
488		2141
489	1	2142	1
490		2143

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