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Revision 1.145 by root, Thu May 29 03:45:37 2008 UTC vs.
Revision 1.244 by root, Fri Jul 17 23:15:57 2009 UTC

1	=head1 => NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
		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.
22		45
23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	46	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
24		47
25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	48	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
26	nowadays. So what is different about AnyEvent?	49	nowadays. So what is different about AnyEvent?
27		50
28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
29	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
30		53
31	First and foremost, I<AnyEvent is not an event model> itself, it only	54	First and foremost, I<AnyEvent is not an event model> itself, it only
32	interfaces to whatever event model the main program happens to use in a	55	interfaces to whatever event model the main program happens to use, in a
33	pragmatic way. For event models and certain classes of immortals alike,	56	pragmatic way. For event models and certain classes of immortals alike,
34	the statement "there can only be one" is a bitter reality: In general,	57	the statement "there can only be one" is a bitter reality: In general,
35	only one event loop can be active at the same time in a process. AnyEvent	58	only one event loop can be active at the same time in a process. AnyEvent
36	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
37		61
38	The goal of AnyEvent is to offer module authors the ability to do event	62	The goal of AnyEvent is to offer module authors the ability to do event
39	programming (waiting for I/O or timer events) without subscribing to a	63	programming (waiting for I/O or timer events) without subscribing to a
40	religion, a way of living, and most importantly: without forcing your	64	religion, a way of living, and most importantly: without forcing your
41	module users into the same thing by forcing them to use the same event	65	module users into the same thing by forcing them to use the same event
42	model you use.	66	model you use.
43		67
44	For modules like POE or IO::Async (which is a total misnomer as it is	68	For modules like POE or IO::Async (which is a total misnomer as it is
45	actually doing all I/O I<synchronously>...), using them in your module is	69	actually doing all I/O I<synchronously>...), using them in your module is
46	like joining a cult: After you joined, you are dependent on them and you	70	like joining a cult: After you joined, you are dependent on them and you
47	cannot use anything else, as it is simply incompatible to everything that	71	cannot use anything else, as they are simply incompatible to everything
48	isn't itself. What's worse, all the potential users of your module are	72	that isn't them. What's worse, all the potential users of your
49	I<also> forced to use the same event loop you use.	73	module are I<also> forced to use the same event loop you use.
50		74
51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	76	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
53	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	77	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
54	your module uses one of those, every user of your module has to use it,	78	your module uses one of those, every user of your module has to use it,
55	too. But if your module uses AnyEvent, it works transparently with all	79	too. But if your module uses AnyEvent, it works transparently with all
56	event models it supports (including stuff like POE and IO::Async, as long	80	event models it supports (including stuff like IO::Async, as long as those
57	as those use one of the supported event loops. It is trivial to add new	81	use one of the supported event loops. It is trivial to add new event loops
58	event loops to AnyEvent, too, so it is future-proof).	82	to AnyEvent, too, so it is future-proof).
59		83
60	In addition to being free of having to use I<the one and only true event	84	In addition to being free of having to use I<the one and only true event
61	model>, AnyEvent also is free of bloat and policy: with POE or similar	85	model>, AnyEvent also is free of bloat and policy: with POE or similar
62	modules, you get an enormous amount of code and strict rules you have to	86	modules, you get an enormous amount of code and strict rules you have to
63	follow. AnyEvent, on the other hand, is lean and up to the point, by only	87	follow. AnyEvent, on the other hand, is lean and up to the point, by only
…		…
121	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
122	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
123	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
124	is in control).	148	is in control).
125		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
126	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
127	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
128	to it).	158	to it).
129		159
130	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.
…		…
132	Many watchers either are used with "recursion" (repeating timers for	162	Many watchers either are used with "recursion" (repeating timers for
133	example), or need to refer to their watcher object in other ways.	163	example), or need to refer to their watcher object in other ways.
134		164
135	An any way to achieve that is this pattern:	165	An any way to achieve that is this pattern:
136		166
137	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {	167	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
138	# you can use $w here, for example to undef it	168	# you can use $w here, for example to undef it
139	undef $w;	169	undef $w;
140	});	170	});
141		171
142	Note that C<my $w; $w => combination. This is necessary because in Perl,	172	Note that C<my $w; $w => combination. This is necessary because in Perl,
143	my variables are only visible after the statement in which they are	173	my variables are only visible after the statement in which they are
144	declared.	174	declared.
145		175
146	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
147		177
148	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
149	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
150		180
151	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	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
152	for events. C<poll> must be a string that is either C<r> or C<w>,	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
153	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
154	respectively. C<cb> is the callback to invoke each time the file handle	191	C<cb> is the callback to invoke each time the file handle becomes ready.
155	becomes ready.
156		192
157	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
158	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
159	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
160		196
…		…
164		200
165	Some event loops issue spurious readyness notifications, so you should	201	Some event loops issue spurious readyness notifications, so you should
166	always use non-blocking calls when reading/writing from/to your file	202	always use non-blocking calls when reading/writing from/to your file
167	handles.	203	handles.
168		204
169	Example:
170
171	# 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
172	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	208	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
173	chomp (my $input = <STDIN>);	209	chomp (my $input = <STDIN>);
174	warn "read: $input\n";	210	warn "read: $input\n";
175	undef $w;	211	undef $w;
176	});	212	});
…		…
186		222
187	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
188	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
189	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
190		226
191	The timer callback will be invoked at most once: if you want a repeating	227	The callback will normally be invoked once only. If you specify another
192	timer you have to create a new watcher (this is a limitation by both Tk	228	parameter, C<interval>, as a strictly positive number (> 0), then the
193	and Glib).	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.
194		232
195	Example:	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.
196		236
197	# fire an event after 7.7 seconds	237	Example: fire an event after 7.7 seconds.
		238
198	my $w = AnyEvent->timer (after => 7.7, cb => sub {	239	my $w = AnyEvent->timer (after => 7.7, cb => sub {
199	warn "timeout\n";	240	warn "timeout\n";
200	});	241	});
201		242
202	# to cancel the timer:	243	# to cancel the timer:
203	undef $w;	244	undef $w;
204		245
205	Example 2:
206
207	# fire an event after 0.5 seconds, then roughly every second	246	Example 2: fire an event after 0.5 seconds, then roughly every second.
208	my $w;
209		247
210	my $cb = sub {
211	# cancel the old timer while creating a new one
212	$w = AnyEvent->timer (after => 1, cb => $cb);	248	my $w = AnyEvent->timer (after => 0.5, interval => 1, cb => sub {
		249	warn "timeout\n";
213	};	250	};
214
215	# start the "loop" by creating the first watcher
216	$w = AnyEvent->timer (after => 0.5, cb => $cb);
217		251
218	=head3 TIMING ISSUES	252	=head3 TIMING ISSUES
219		253
220	There are two ways to handle timers: based on real time (relative, "fire	254	There are two ways to handle timers: based on real time (relative, "fire
221	in 10 seconds") and based on wallclock time (absolute, "fire at 12	255	in 10 seconds") and based on wallclock time (absolute, "fire at 12
…		…
294	In either case, if you care (and in most cases, you don't), then you	328	In either case, if you care (and in most cases, you don't), then you
295	can get whatever behaviour you want with any event loop, by taking the	329	can get whatever behaviour you want with any event loop, by taking the
296	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
297	account.	331	account.
298		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
299	=back	348	=back
300		349
301	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
302		351
303	You can watch for signals using a signal watcher, C<signal> is the signal	352	You can watch for signals using a signal watcher, C<signal> is the signal
304	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
305	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
306		355
307	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
308	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
309	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
310		359
…		…
312	invocation, and callback invocation will be synchronous. Synchronous means	361	invocation, and callback invocation will be synchronous. Synchronous means
313	that it might take a while until the signal gets handled by the process,	362	that it might take a while until the signal gets handled by the process,
314	but it is guaranteed not to interrupt any other callbacks.	363	but it is guaranteed not to interrupt any other callbacks.
315		364
316	The main advantage of using these watchers is that you can share a signal	365	The main advantage of using these watchers is that you can share a signal
317	between multiple watchers.	366	between multiple watchers, and AnyEvent will ensure that signals will not
		367	interrupt your program at bad times.
318		368
319	This watcher might use C<%SIG>, so programs overwriting those signals	369	This watcher might use C<%SIG> (depending on the event loop used),
320	directly will likely not work correctly.	370	so programs overwriting those signals directly will likely not work
		371	correctly.
		372
		373	Also note that many event loops (e.g. Glib, Tk, Qt, IO::Async) do not
		374	support attaching callbacks to signals, which is a pity, as you cannot do
		375	race-free signal handling in perl. AnyEvent will try to do it's best, but
		376	in some cases, signals will be delayed. The maximum time a signal might
		377	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		378	seconds). This variable can be changed only before the first signal
		379	watcher is created, and should be left alone otherwise. Higher values
		380	will cause fewer spurious wake-ups, which is better for power and CPU
		381	saving. All these problems can be avoided by installing the optional
		382	L<Async::Interrupt> module.
321		383
322	Example: exit on SIGINT	384	Example: exit on SIGINT
323		385
324	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	386	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
325		387
326	=head2 CHILD PROCESS WATCHERS	388	=head2 CHILD PROCESS WATCHERS
327		389
328	You can also watch on a child process exit and catch its exit status.	390	You can also watch on a child process exit and catch its exit status.
329		391
330	The child process is specified by the C<pid> argument (if set to C<0>, it	392	The child process is specified by the C<pid> argument (if set to C<0>, it
331	watches for any child process exit). The watcher will trigger as often	393	watches for any child process exit). The watcher will triggered only when
332	as status change for the child are received. This works by installing a	394	the child process has finished and an exit status is available, not on
333	signal handler for C<SIGCHLD>. The callback will be called with the pid	395	any trace events (stopped/continued).
334	and exit status (as returned by waitpid), so unlike other watcher types,	396
335	you I<can> rely on child watcher callback arguments.	397	The callback will be called with the pid and exit status (as returned by
		398	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		399	callback arguments.
		400
		401	This watcher type works by installing a signal handler for C<SIGCHLD>,
		402	and since it cannot be shared, nothing else should use SIGCHLD or reap
		403	random child processes (waiting for specific child processes, e.g. inside
		404	C<system>, is just fine).
336		405
337	There is a slight catch to child watchers, however: you usually start them	406	There is a slight catch to child watchers, however: you usually start them
338	I<after> the child process was created, and this means the process could	407	I<after> the child process was created, and this means the process could
339	have exited already (and no SIGCHLD will be sent anymore).	408	have exited already (and no SIGCHLD will be sent anymore).
340		409
341	Not all event models handle this correctly (POE doesn't), but even for	410	Not all event models handle this correctly (neither POE nor IO::Async do,
		411	see their AnyEvent::Impl manpages for details), but even for event models
342	event models that I<do> handle this correctly, they usually need to be	412	that I<do> handle this correctly, they usually need to be loaded before
343	loaded before the process exits (i.e. before you fork in the first place).	413	the process exits (i.e. before you fork in the first place). AnyEvent's
		414	pure perl event loop handles all cases correctly regardless of when you
		415	start the watcher.
344		416
345	This means you cannot create a child watcher as the very first thing in an	417	This means you cannot create a child watcher as the very first
346	AnyEvent program, you I<have> to create at least one watcher before you	418	thing in an AnyEvent program, you I<have> to create at least one
347	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	419	watcher before you C<fork> the child (alternatively, you can call
		420	C<AnyEvent::detect>).
		421
		422	As most event loops do not support waiting for child events, they will be
		423	emulated by AnyEvent in most cases, in which the latency and race problems
		424	mentioned in the description of signal watchers apply.
348		425
349	Example: fork a process and wait for it	426	Example: fork a process and wait for it
350		427
351	my $done = AnyEvent->condvar;	428	my $done = AnyEvent->condvar;
352		429
353	my $pid = fork or exit 5;	430	my $pid = fork or exit 5;
354		431
355	my $w = AnyEvent->child (	432	my $w = AnyEvent->child (
356	pid => $pid,	433	pid => $pid,
357	cb => sub {	434	cb => sub {
358	my ($pid, $status) = @_;	435	my ($pid, $status) = @_;
359	warn "pid $pid exited with status $status";	436	warn "pid $pid exited with status $status";
360	$done->send;	437	$done->send;
361	},	438	},
362	);	439	);
363		440
364	# do something else, then wait for process exit	441	# do something else, then wait for process exit
365	$done->recv;	442	$done->recv;
		443
		444	=head2 IDLE WATCHERS
		445
		446	Sometimes there is a need to do something, but it is not so important
		447	to do it instantly, but only when there is nothing better to do. This
		448	"nothing better to do" is usually defined to be "no other events need
		449	attention by the event loop".
		450
		451	Idle watchers ideally get invoked when the event loop has nothing
		452	better to do, just before it would block the process to wait for new
		453	events. Instead of blocking, the idle watcher is invoked.
		454
		455	Most event loops unfortunately do not really support idle watchers (only
		456	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		457	will simply call the callback "from time to time".
		458
		459	Example: read lines from STDIN, but only process them when the
		460	program is otherwise idle:
		461
		462	my @lines; # read data
		463	my $idle_w;
		464	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		465	push @lines, scalar <STDIN>;
		466
		467	# start an idle watcher, if not already done
		468	$idle_w ||= AnyEvent->idle (cb => sub {
		469	# handle only one line, when there are lines left
		470	if (my $line = shift @lines) {
		471	print "handled when idle: $line";
		472	} else {
		473	# otherwise disable the idle watcher again
		474	undef $idle_w;
		475	}
		476	});
		477	});
366		478
367	=head2 CONDITION VARIABLES	479	=head2 CONDITION VARIABLES
368		480
369	If you are familiar with some event loops you will know that all of them	481	If you are familiar with some event loops you will know that all of them
370	require you to run some blocking "loop", "run" or similar function that	482	require you to run some blocking "loop", "run" or similar function that
371	will actively watch for new events and call your callbacks.	483	will actively watch for new events and call your callbacks.
372		484
373	AnyEvent is different, it expects somebody else to run the event loop and	485	AnyEvent is slightly different: it expects somebody else to run the event
374	will only block when necessary (usually when told by the user).	486	loop and will only block when necessary (usually when told by the user).
375		487
376	The instrument to do that is called a "condition variable", so called	488	The instrument to do that is called a "condition variable", so called
377	because they represent a condition that must become true.	489	because they represent a condition that must become true.
		490
		491	Now is probably a good time to look at the examples further below.
378		492
379	Condition variables can be created by calling the C<< AnyEvent->condvar	493	Condition variables can be created by calling the C<< AnyEvent->condvar
380	>> method, usually without arguments. The only argument pair allowed is	494	>> method, usually without arguments. The only argument pair allowed is
381	C<cb>, which specifies a callback to be called when the condition variable	495	C<cb>, which specifies a callback to be called when the condition variable
382	becomes true.	496	becomes true, with the condition variable as the first argument (but not
		497	the results).
383		498
384	After creation, the condition variable is "false" until it becomes "true"	499	After creation, the condition variable is "false" until it becomes "true"
385	by calling the C<send> method (or calling the condition variable as if it	500	by calling the C<send> method (or calling the condition variable as if it
386	were a callback, read about the caveats in the description for the C<<	501	were a callback, read about the caveats in the description for the C<<
387	->send >> method).	502	->send >> method).
…		…
433	after => 1,	548	after => 1,
434	cb => sub { $result_ready->send },	549	cb => sub { $result_ready->send },
435	);	550	);
436		551
437	# this "blocks" (while handling events) till the callback	552	# this "blocks" (while handling events) till the callback
438	# calls send	553	# calls -<send
439	$result_ready->recv;	554	$result_ready->recv;
440		555
441	Example: wait for a timer, but take advantage of the fact that	556	Example: wait for a timer, but take advantage of the fact that condition
442	condition variables are also code references.	557	variables are also callable directly.
443		558
444	my $done = AnyEvent->condvar;	559	my $done = AnyEvent->condvar;
445	my $delay = AnyEvent->timer (after => 5, cb => $done);	560	my $delay = AnyEvent->timer (after => 5, cb => $done);
446	$done->recv;	561	$done->recv;
		562
		563	Example: Imagine an API that returns a condvar and doesn't support
		564	callbacks. This is how you make a synchronous call, for example from
		565	the main program:
		566
		567	use AnyEvent::CouchDB;
		568
		569	...
		570
		571	my @info = $couchdb->info->recv;
		572
		573	And this is how you would just set a callback to be called whenever the
		574	results are available:
		575
		576	$couchdb->info->cb (sub {
		577	my @info = $_[0]->recv;
		578	});
447		579
448	=head3 METHODS FOR PRODUCERS	580	=head3 METHODS FOR PRODUCERS
449		581
450	These methods should only be used by the producing side, i.e. the	582	These methods should only be used by the producing side, i.e. the
451	code/module that eventually sends the signal. Note that it is also	583	code/module that eventually sends the signal. Note that it is also
…		…
464	immediately from within send.	596	immediately from within send.
465		597
466	Any arguments passed to the C<send> call will be returned by all	598	Any arguments passed to the C<send> call will be returned by all
467	future C<< ->recv >> calls.	599	future C<< ->recv >> calls.
468		600
469	Condition variables are overloaded so one can call them directly	601	Condition variables are overloaded so one can call them directly (as if
470	(as a code reference). Calling them directly is the same as calling	602	they were a code reference). Calling them directly is the same as calling
471	C<send>. Note, however, that many C-based event loops do not handle	603	C<send>.
472	overloading, so as tempting as it may be, passing a condition variable
473	instead of a callback does not work. Both the pure perl and EV loops
474	support overloading, however, as well as all functions that use perl to
475	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
476	example).
477		604
478	=item $cv->croak ($error)	605	=item $cv->croak ($error)
479		606
480	Similar to send, but causes all call's to C<< ->recv >> to invoke	607	Similar to send, but causes all call's to C<< ->recv >> to invoke
481	C<Carp::croak> with the given error message/object/scalar.	608	C<Carp::croak> with the given error message/object/scalar.
482		609
483	This can be used to signal any errors to the condition variable	610	This can be used to signal any errors to the condition variable
484	user/consumer.	611	user/consumer. Doing it this way instead of calling C<croak> directly
		612	delays the error detetcion, but has the overwhelmign advantage that it
		613	diagnoses the error at the place where the result is expected, and not
		614	deep in some event clalback without connection to the actual code causing
		615	the problem.
485		616
486	=item $cv->begin ([group callback])	617	=item $cv->begin ([group callback])
487		618
488	=item $cv->end	619	=item $cv->end
489
490	These two methods are EXPERIMENTAL and MIGHT CHANGE.
491		620
492	These two methods can be used to combine many transactions/events into	621	These two methods can be used to combine many transactions/events into
493	one. For example, a function that pings many hosts in parallel might want	622	one. For example, a function that pings many hosts in parallel might want
494	to use a condition variable for the whole process.	623	to use a condition variable for the whole process.
495		624
…		…
497	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	626	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
498	>>, the (last) callback passed to C<begin> will be executed. That callback	627	>>, the (last) callback passed to C<begin> will be executed. That callback
499	is I<supposed> to call C<< ->send >>, but that is not required. If no	628	is I<supposed> to call C<< ->send >>, but that is not required. If no
500	callback was set, C<send> will be called without any arguments.	629	callback was set, C<send> will be called without any arguments.
501		630
502	Let's clarify this with the ping example:	631	You can think of C<< $cv->send >> giving you an OR condition (one call
		632	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		633	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		634
		635	Let's start with a simple example: you have two I/O watchers (for example,
		636	STDOUT and STDERR for a program), and you want to wait for both streams to
		637	close before activating a condvar:
		638
		639	my $cv = AnyEvent->condvar;
		640
		641	$cv->begin; # first watcher
		642	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		643	defined sysread $fh1, my $buf, 4096
		644	or $cv->end;
		645	});
		646
		647	$cv->begin; # second watcher
		648	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		649	defined sysread $fh2, my $buf, 4096
		650	or $cv->end;
		651	});
		652
		653	$cv->recv;
		654
		655	This works because for every event source (EOF on file handle), there is
		656	one call to C<begin>, so the condvar waits for all calls to C<end> before
		657	sending.
		658
		659	The ping example mentioned above is slightly more complicated, as the
		660	there are results to be passwd back, and the number of tasks that are
		661	begung can potentially be zero:
503		662
504	my $cv = AnyEvent->condvar;	663	my $cv = AnyEvent->condvar;
505		664
506	my %result;	665	my %result;
507	$cv->begin (sub { $cv->send (\%result) });	666	$cv->begin (sub { $cv->send (\%result) });
…		…
527	loop, which serves two important purposes: first, it sets the callback	686	loop, which serves two important purposes: first, it sets the callback
528	to be called once the counter reaches C<0>, and second, it ensures that	687	to be called once the counter reaches C<0>, and second, it ensures that
529	C<send> is called even when C<no> hosts are being pinged (the loop	688	C<send> is called even when C<no> hosts are being pinged (the loop
530	doesn't execute once).	689	doesn't execute once).
531		690
532	This is the general pattern when you "fan out" into multiple subrequests:	691	This is the general pattern when you "fan out" into multiple (but
533	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	692	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
534	is called at least once, and then, for each subrequest you start, call	693	the callback and ensure C<end> is called at least once, and then, for each
535	C<begin> and for each subrequest you finish, call C<end>.	694	subrequest you start, call C<begin> and for each subrequest you finish,
		695	call C<end>.
536		696
537	=back	697	=back
538		698
539	=head3 METHODS FOR CONSUMERS	699	=head3 METHODS FOR CONSUMERS
540		700
…		…
556	function will call C<croak>.	716	function will call C<croak>.
557		717
558	In list context, all parameters passed to C<send> will be returned,	718	In list context, all parameters passed to C<send> will be returned,
559	in scalar context only the first one will be returned.	719	in scalar context only the first one will be returned.
560		720
		721	Note that doing a blocking wait in a callback is not supported by any
		722	event loop, that is, recursive invocation of a blocking C<< ->recv
		723	>> is not allowed, and the C<recv> call will C<croak> if such a
		724	condition is detected. This condition can be slightly loosened by using
		725	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		726	any thread that doesn't run the event loop itself.
		727
561	Not all event models support a blocking wait - some die in that case	728	Not all event models support a blocking wait - some die in that case
562	(programs might want to do that to stay interactive), so I<if you are	729	(programs might want to do that to stay interactive), so I<if you are
563	using this from a module, never require a blocking wait>, but let the	730	using this from a module, never require a blocking wait>. Instead, let the
564	caller decide whether the call will block or not (for example, by coupling	731	caller decide whether the call will block or not (for example, by coupling
565	condition variables with some kind of request results and supporting	732	condition variables with some kind of request results and supporting
566	callbacks so the caller knows that getting the result will not block,	733	callbacks so the caller knows that getting the result will not block,
567	while still supporting blocking waits if the caller so desires).	734	while still supporting blocking waits if the caller so desires).
568		735
569	Another reason I<never> to C<< ->recv >> in a module is that you cannot
570	sensibly have two C<< ->recv >>'s in parallel, as that would require
571	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
572	can supply.
573
574	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
575	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
576	versions and also integrates coroutines into AnyEvent, making blocking
577	C<< ->recv >> calls perfectly safe as long as they are done from another
578	coroutine (one that doesn't run the event loop).
579
580	You can ensure that C<< -recv >> never blocks by setting a callback and	736	You can ensure that C<< -recv >> never blocks by setting a callback and
581	only calling C<< ->recv >> from within that callback (or at a later	737	only calling C<< ->recv >> from within that callback (or at a later
582	time). This will work even when the event loop does not support blocking	738	time). This will work even when the event loop does not support blocking
583	waits otherwise.	739	waits otherwise.
584		740
585	=item $bool = $cv->ready	741	=item $bool = $cv->ready
586		742
587	Returns true when the condition is "true", i.e. whether C<send> or	743	Returns true when the condition is "true", i.e. whether C<send> or
588	C<croak> have been called.	744	C<croak> have been called.
589		745
590	=item $cb = $cv->cb ([new callback])	746	=item $cb = $cv->cb ($cb->($cv))
591		747
592	This is a mutator function that returns the callback set and optionally	748	This is a mutator function that returns the callback set and optionally
593	replaces it before doing so.	749	replaces it before doing so.
594		750
595	The callback will be called when the condition becomes "true", i.e. when	751	The callback will be called when the condition becomes "true", i.e. when
596	C<send> or C<croak> are called. Calling C<recv> inside the callback	752	C<send> or C<croak> are called, with the only argument being the condition
597	or at any later time is guaranteed not to block.	753	variable itself. Calling C<recv> inside the callback or at any later time
		754	is guaranteed not to block.
598		755
599	=back	756	=back
600		757
		758	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		759
		760	The available backend classes are (every class has its own manpage):
		761
		762	=over 4
		763
		764	=item Backends that are autoprobed when no other event loop can be found.
		765
		766	EV is the preferred backend when no other event loop seems to be in
		767	use. If EV is not installed, then AnyEvent will try Event, and, failing
		768	that, will fall back to its own pure-perl implementation, which is
		769	available everywhere as it comes with AnyEvent itself.
		770
		771	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		772	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		773	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		774
		775	=item Backends that are transparently being picked up when they are used.
		776
		777	These will be used when they are currently loaded when the first watcher
		778	is created, in which case it is assumed that the application is using
		779	them. This means that AnyEvent will automatically pick the right backend
		780	when the main program loads an event module before anything starts to
		781	create watchers. Nothing special needs to be done by the main program.
		782
		783	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		784	AnyEvent::Impl::Tk based on Tk, very broken.
		785	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		786	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		787
		788	=item Backends with special needs.
		789
		790	Qt requires the Qt::Application to be instantiated first, but will
		791	otherwise be picked up automatically. As long as the main program
		792	instantiates the application before any AnyEvent watchers are created,
		793	everything should just work.
		794
		795	AnyEvent::Impl::Qt based on Qt.
		796
		797	Support for IO::Async can only be partial, as it is too broken and
		798	architecturally limited to even support the AnyEvent API. It also
		799	is the only event loop that needs the loop to be set explicitly, so
		800	it can only be used by a main program knowing about AnyEvent. See
		801	L<AnyEvent::Impl::Async> for the gory details.
		802
		803	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		804
		805	=item Event loops that are indirectly supported via other backends.
		806
		807	Some event loops can be supported via other modules:
		808
		809	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		810
		811	B<WxWidgets> has no support for watching file handles. However, you can
		812	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		813	polls 20 times per second, which was considered to be too horrible to even
		814	consider for AnyEvent.
		815
		816	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		817	backend, so it can be supported through POE.
		818
		819	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		820	load L<POE> when detecting them, in the hope that POE will pick them up,
		821	in which case everything will be automatic.
		822
		823	=back
		824
601	=head1 GLOBAL VARIABLES AND FUNCTIONS	825	=head1 GLOBAL VARIABLES AND FUNCTIONS
602		826
		827	These are not normally required to use AnyEvent, but can be useful to
		828	write AnyEvent extension modules.
		829
603	=over 4	830	=over 4
604		831
605	=item $AnyEvent::MODEL	832	=item $AnyEvent::MODEL
606		833
607	Contains C<undef> until the first watcher is being created. Then it	834	Contains C<undef> until the first watcher is being created, before the
		835	backend has been autodetected.
		836
608	contains the event model that is being used, which is the name of the	837	Afterwards it contains the event model that is being used, which is the
609	Perl class implementing the model. This class is usually one of the	838	name of the Perl class implementing the model. This class is usually one
610	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	839	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
611	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	840	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
612		841	will be C<urxvt::anyevent>).
613	The known classes so far are:
614
615	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
616	AnyEvent::Impl::Event based on Event, second best choice.
617	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
618	AnyEvent::Impl::Glib based on Glib, third-best choice.
619	AnyEvent::Impl::Tk based on Tk, very bad choice.
620	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
621	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
622	AnyEvent::Impl::POE based on POE, not generic enough for full support.
623
624	There is no support for WxWidgets, as WxWidgets has no support for
625	watching file handles. However, you can use WxWidgets through the
626	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
627	second, which was considered to be too horrible to even consider for
628	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
629	it's adaptor.
630
631	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
632	autodetecting them.
633		842
634	=item AnyEvent::detect	843	=item AnyEvent::detect
635		844
636	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	845	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
637	if necessary. You should only call this function right before you would	846	if necessary. You should only call this function right before you would
638	have created an AnyEvent watcher anyway, that is, as late as possible at	847	have created an AnyEvent watcher anyway, that is, as late as possible at
639	runtime.	848	runtime, and not e.g. while initialising of your module.
		849
		850	If you need to do some initialisation before AnyEvent watchers are
		851	created, use C<post_detect>.
640		852
641	=item $guard = AnyEvent::post_detect { BLOCK }	853	=item $guard = AnyEvent::post_detect { BLOCK }
642		854
643	Arranges for the code block to be executed as soon as the event model is	855	Arranges for the code block to be executed as soon as the event model is
644	autodetected (or immediately if this has already happened).	856	autodetected (or immediately if this has already happened).
		857
		858	The block will be executed I<after> the actual backend has been detected
		859	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		860	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		861	other initialisations - see the sources of L<AnyEvent::Strict> or
		862	L<AnyEvent::AIO> to see how this is used.
		863
		864	The most common usage is to create some global watchers, without forcing
		865	event module detection too early, for example, L<AnyEvent::AIO> creates
		866	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		867	avoid autodetecting the event module at load time.
645		868
646	If called in scalar or list context, then it creates and returns an object	869	If called in scalar or list context, then it creates and returns an object
647	that automatically removes the callback again when it is destroyed. See	870	that automatically removes the callback again when it is destroyed. See
648	L<Coro::BDB> for a case where this is useful.	871	L<Coro::BDB> for a case where this is useful.
649		872
…		…
652	If there are any code references in this array (you can C<push> to it	875	If there are any code references in this array (you can C<push> to it
653	before or after loading AnyEvent), then they will called directly after	876	before or after loading AnyEvent), then they will called directly after
654	the event loop has been chosen.	877	the event loop has been chosen.
655		878
656	You should check C<$AnyEvent::MODEL> before adding to this array, though:	879	You should check C<$AnyEvent::MODEL> before adding to this array, though:
657	if it contains a true value then the event loop has already been detected,	880	if it is defined then the event loop has already been detected, and the
658	and the array will be ignored.	881	array will be ignored.
659		882
660	Best use C<AnyEvent::post_detect { BLOCK }> instead.	883	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		884	it,as it takes care of these details.
		885
		886	This variable is mainly useful for modules that can do something useful
		887	when AnyEvent is used and thus want to know when it is initialised, but do
		888	not need to even load it by default. This array provides the means to hook
		889	into AnyEvent passively, without loading it.
661		890
662	=back	891	=back
663		892
664	=head1 WHAT TO DO IN A MODULE	893	=head1 WHAT TO DO IN A MODULE
665		894
…		…
720		949
721		950
722	=head1 OTHER MODULES	951	=head1 OTHER MODULES
723		952
724	The following is a non-exhaustive list of additional modules that use	953	The following is a non-exhaustive list of additional modules that use
725	AnyEvent and can therefore be mixed easily with other AnyEvent modules	954	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
726	in the same program. Some of the modules come with AnyEvent, some are	955	modules and other event loops in the same program. Some of the modules
727	available via CPAN.	956	come with AnyEvent, most are available via CPAN.
728		957
729	=over 4	958	=over 4
730		959
731	=item L<AnyEvent::Util>	960	=item L<AnyEvent::Util>
732		961
733	Contains various utility functions that replace often-used but blocking	962	Contains various utility functions that replace often-used but blocking
734	functions such as C<inet_aton> by event-/callback-based versions.	963	functions such as C<inet_aton> by event-/callback-based versions.
735
736	=item L<AnyEvent::Handle>
737
738	Provide read and write buffers and manages watchers for reads and writes.
739		964
740	=item L<AnyEvent::Socket>	965	=item L<AnyEvent::Socket>
741		966
742	Provides various utility functions for (internet protocol) sockets,	967	Provides various utility functions for (internet protocol) sockets,
743	addresses and name resolution. Also functions to create non-blocking tcp	968	addresses and name resolution. Also functions to create non-blocking tcp
744	connections or tcp servers, with IPv6 and SRV record support and more.	969	connections or tcp servers, with IPv6 and SRV record support and more.
745		970
		971	=item L<AnyEvent::Handle>
		972
		973	Provide read and write buffers, manages watchers for reads and writes,
		974	supports raw and formatted I/O, I/O queued and fully transparent and
		975	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
		976
746	=item L<AnyEvent::DNS>	977	=item L<AnyEvent::DNS>
747		978
748	Provides rich asynchronous DNS resolver capabilities.	979	Provides rich asynchronous DNS resolver capabilities.
749		980
		981	=item L<AnyEvent::HTTP>
		982
		983	A simple-to-use HTTP library that is capable of making a lot of concurrent
		984	HTTP requests.
		985
750	=item L<AnyEvent::HTTPD>	986	=item L<AnyEvent::HTTPD>
751		987
752	Provides a simple web application server framework.	988	Provides a simple web application server framework.
753		989
754	=item L<AnyEvent::FastPing>	990	=item L<AnyEvent::FastPing>
755		991
756	The fastest ping in the west.	992	The fastest ping in the west.
757		993
		994	=item L<AnyEvent::DBI>
		995
		996	Executes L<DBI> requests asynchronously in a proxy process.
		997
		998	=item L<AnyEvent::AIO>
		999
		1000	Truly asynchronous I/O, should be in the toolbox of every event
		1001	programmer. AnyEvent::AIO transparently fuses L<IO::AIO> and AnyEvent
		1002	together.
		1003
		1004	=item L<AnyEvent::BDB>
		1005
		1006	Truly asynchronous Berkeley DB access. AnyEvent::BDB transparently fuses
		1007	L<BDB> and AnyEvent together.
		1008
		1009	=item L<AnyEvent::GPSD>
		1010
		1011	A non-blocking interface to gpsd, a daemon delivering GPS information.
		1012
758	=item L<Net::IRC3>	1013	=item L<AnyEvent::IRC>
759		1014
760	AnyEvent based IRC client module family.	1015	AnyEvent based IRC client module family (replacing the older Net::IRC3).
761		1016
762	=item L<Net::XMPP2>	1017	=item L<AnyEvent::XMPP>
763		1018
764	AnyEvent based XMPP (Jabber protocol) module family.	1019	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1020	Net::XMPP2>.
		1021
		1022	=item L<AnyEvent::IGS>
		1023
		1024	A non-blocking interface to the Internet Go Server protocol (used by
		1025	L<App::IGS>).
765		1026
766	=item L<Net::FCP>	1027	=item L<Net::FCP>
767		1028
768	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1029	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
769	of AnyEvent.	1030	of AnyEvent.
…		…
774		1035
775	=item L<Coro>	1036	=item L<Coro>
776		1037
777	Has special support for AnyEvent via L<Coro::AnyEvent>.	1038	Has special support for AnyEvent via L<Coro::AnyEvent>.
778		1039
779	=item L<AnyEvent::AIO>, L<IO::AIO>
780
781	Truly asynchronous I/O, should be in the toolbox of every event
782	programmer. AnyEvent::AIO transparently fuses IO::AIO and AnyEvent
783	together.
784
785	=item L<AnyEvent::BDB>, L<BDB>
786
787	Truly asynchronous Berkeley DB access. AnyEvent::AIO transparently fuses
788	IO::AIO and AnyEvent together.
789
790	=item L<IO::Lambda>
791
792	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
793
794	=back	1040	=back
795		1041
796	=cut	1042	=cut
797		1043
798	package AnyEvent;	1044	package AnyEvent;
799		1045
		1046	# basically a tuned-down version of common::sense
		1047	sub common_sense {
800	no warnings;	1048	# no warnings
801	use strict;	1049	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1050	# use strict vars subs
		1051	$^H |= 0x00000600;
		1052	}
802		1053
		1054	BEGIN { AnyEvent::common_sense }
		1055
803	use Carp;	1056	use Carp ();
804		1057
805	our $VERSION = '4.1';	1058	our $VERSION = 4.83;
806	our $MODEL;	1059	our $MODEL;
807		1060
808	our $AUTOLOAD;	1061	our $AUTOLOAD;
809	our @ISA;	1062	our @ISA;
810		1063
811	our @REGISTRY;	1064	our @REGISTRY;
812		1065
813	our $WIN32;	1066	our $WIN32;
814		1067
		1068	our $VERBOSE;
		1069
815	BEGIN {	1070	BEGIN {
816	my $win32 = ! ! ($^O =~ /mswin32/i);	1071	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
817	eval "sub WIN32(){ $win32 }";	1072	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
818	}
819		1073
		1074	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1075	if ${^TAINT};
		1076
820	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1077	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1078
		1079	}
		1080
		1081	our $MAX_SIGNAL_LATENCY = 10;
821		1082
822	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1083	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
823		1084
824	{	1085	{
825	my $idx;	1086	my $idx;
…		…
833	[Event:: => AnyEvent::Impl::Event::],	1094	[Event:: => AnyEvent::Impl::Event::],
834	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1095	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
835	# everything below here will not be autoprobed	1096	# everything below here will not be autoprobed
836	# as the pureperl backend should work everywhere	1097	# as the pureperl backend should work everywhere
837	# and is usually faster	1098	# and is usually faster
838	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
839	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1099	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
840	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1100	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1101	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
841	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1102	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
842	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1103	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
843	[Wx:: => AnyEvent::Impl::POE::],	1104	[Wx:: => AnyEvent::Impl::POE::],
844	[Prima:: => AnyEvent::Impl::POE::],	1105	[Prima:: => AnyEvent::Impl::POE::],
		1106	# IO::Async is just too broken - we would need workarounds for its
		1107	# byzantine signal and broken child handling, among others.
		1108	# IO::Async is rather hard to detect, as it doesn't have any
		1109	# obvious default class.
		1110	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1111	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1112	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
845	);	1113	);
846		1114
847	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1115	our %method = map +($_ => 1),
		1116	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
848		1117
849	our @post_detect;	1118	our @post_detect;
850		1119
851	sub post_detect(&) {	1120	sub post_detect(&) {
852	my ($cb) = @_;	1121	my ($cb) = @_;
…		…
857	1	1126	1
858	} else {	1127	} else {
859	push @post_detect, $cb;	1128	push @post_detect, $cb;
860		1129
861	defined wantarray	1130	defined wantarray
862	? bless \$cb, "AnyEvent::Util::PostDetect"	1131	? bless \$cb, "AnyEvent::Util::postdetect"
863	: ()	1132	: ()
864	}	1133	}
865	}	1134	}
866		1135
867	sub AnyEvent::Util::PostDetect::DESTROY {	1136	sub AnyEvent::Util::postdetect::DESTROY {
868	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1137	@post_detect = grep $_ != ${$_[0]}, @post_detect;
869	}	1138	}
870		1139
871	sub detect() {	1140	sub detect() {
872	unless ($MODEL) {	1141	unless ($MODEL) {
873	no strict 'refs';
874	local $SIG{__DIE__};	1142	local $SIG{__DIE__};
875		1143
876	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1144	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
877	my $model = "AnyEvent::Impl::$1";	1145	my $model = "AnyEvent::Impl::$1";
878	if (eval "require $model") {	1146	if (eval "require $model") {
879	$MODEL = $model;	1147	$MODEL = $model;
880	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1148	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
881	} else {	1149	} else {
882	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1150	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
883	}	1151	}
884	}	1152	}
885		1153
886	# check for already loaded models	1154	# check for already loaded models
887	unless ($MODEL) {	1155	unless ($MODEL) {
888	for (@REGISTRY, @models) {	1156	for (@REGISTRY, @models) {
889	my ($package, $model) = @$_;	1157	my ($package, $model) = @$_;
890	if (${"$package\::VERSION"} > 0) {	1158	if (${"$package\::VERSION"} > 0) {
891	if (eval "require $model") {	1159	if (eval "require $model") {
892	$MODEL = $model;	1160	$MODEL = $model;
893	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1161	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
894	last;	1162	last;
895	}	1163	}
896	}	1164	}
897	}	1165	}
898		1166
…		…
903	my ($package, $model) = @$_;	1171	my ($package, $model) = @$_;
904	if (eval "require $package"	1172	if (eval "require $package"
905	and ${"$package\::VERSION"} > 0	1173	and ${"$package\::VERSION"} > 0
906	and eval "require $model") {	1174	and eval "require $model") {
907	$MODEL = $model;	1175	$MODEL = $model;
908	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1176	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
909	last;	1177	last;
910	}	1178	}
911	}	1179	}
912		1180
913	$MODEL	1181	$MODEL
914	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1182	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
915	}	1183	}
916	}	1184	}
917		1185
		1186	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1187
918	unshift @ISA, $MODEL;	1188	unshift @ISA, $MODEL;
919	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1189
		1190	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
920		1191
921	(shift @post_detect)->() while @post_detect;	1192	(shift @post_detect)->() while @post_detect;
922	}	1193	}
923		1194
924	$MODEL	1195	$MODEL
…		…
926		1197
927	sub AUTOLOAD {	1198	sub AUTOLOAD {
928	(my $func = $AUTOLOAD) =~ s/.*://;	1199	(my $func = $AUTOLOAD) =~ s/.*://;
929		1200
930	$method{$func}	1201	$method{$func}
931	or croak "$func: not a valid method for AnyEvent objects";	1202	or Carp::croak "$func: not a valid method for AnyEvent objects";
932		1203
933	detect unless $MODEL;	1204	detect unless $MODEL;
934		1205
935	my $class = shift;	1206	my $class = shift;
936	$class->$func (@_);	1207	$class->$func (@_);
937	}	1208	}
938		1209
		1210	# utility function to dup a filehandle. this is used by many backends
		1211	# to support binding more than one watcher per filehandle (they usually
		1212	# allow only one watcher per fd, so we dup it to get a different one).
		1213	sub _dupfh($$;$$) {
		1214	my ($poll, $fh, $r, $w) = @_;
		1215
		1216	# cygwin requires the fh mode to be matching, unix doesn't
		1217	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
		1218
		1219	open my $fh2, $mode, $fh
		1220	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
		1221
		1222	# we assume CLOEXEC is already set by perl in all important cases
		1223
		1224	($fh2, $rw)
		1225	}
		1226
939	package AnyEvent::Base;	1227	package AnyEvent::Base;
940		1228
941	# default implementation for now and time	1229	# default implementations for many methods
942		1230
943	use Time::HiRes ();	1231	sub _time {
		1232	# probe for availability of Time::HiRes
		1233	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1234	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1235	*_time = \&Time::HiRes::time;
		1236	# if (eval "use POSIX (); (POSIX::times())...
		1237	} else {
		1238	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1239	*_time = sub { time }; # epic fail
		1240	}
944		1241
945	sub time { Time::HiRes::time }	1242	&_time
946	sub now { Time::HiRes::time }	1243	}
		1244
		1245	sub time { _time }
		1246	sub now { _time }
		1247	sub now_update { }
947		1248
948	# default implementation for ->condvar	1249	# default implementation for ->condvar
949		1250
950	sub condvar {	1251	sub condvar {
951	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1252	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
952	}	1253	}
953		1254
954	# default implementation for ->signal	1255	# default implementation for ->signal
955		1256
956	our %SIG_CB;	1257	our $HAVE_ASYNC_INTERRUPT;
		1258	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1259	our (%SIG_ASY, %SIG_ASY_W);
		1260	our ($SIG_COUNT, $SIG_TW);
957		1261
		1262	sub _signal_exec {
		1263	$HAVE_ASYNC_INTERRUPT
		1264	? $SIGPIPE_R->drain
		1265	: sysread $SIGPIPE_R, my $dummy, 9;
		1266
		1267	while (%SIG_EV) {
		1268	for (keys %SIG_EV) {
		1269	delete $SIG_EV{$_};
		1270	$_->() for values %{ $SIG_CB{$_} || {} };
		1271	}
		1272	}
		1273	}
		1274
958	sub signal {	1275	sub _signal {
959	my (undef, %arg) = @_;	1276	my (undef, %arg) = @_;
960		1277
961	my $signal = uc $arg{signal}	1278	my $signal = uc $arg{signal}
962	or Carp::croak "required option 'signal' is missing";	1279	or Carp::croak "required option 'signal' is missing";
963		1280
964	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1281	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1282
		1283	if ($HAVE_ASYNC_INTERRUPT) {
		1284	# async::interrupt
		1285
		1286	$SIG_ASY{$signal} ||= do {
		1287	my $asy = new Async::Interrupt
		1288	cb => sub { undef $SIG_EV{$signal} },
		1289	signal => $signal,
		1290	pipe => [$SIGPIPE_R->filenos],
		1291	;
		1292	$asy->pipe_autodrain (0);
		1293
		1294	$asy
		1295	};
		1296
		1297	} else {
		1298	# pure perl
		1299
965	$SIG{$signal} ||= sub {	1300	$SIG{$signal} ||= sub {
966	$_->() for values %{ $SIG_CB{$signal} || {} };	1301	local $!;
		1302	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1303	undef $SIG_EV{$signal};
		1304	};
		1305
		1306	# can't do signal processing without introducing races in pure perl,
		1307	# so limit the signal latency.
		1308	++$SIG_COUNT;
		1309	$SIG_TW ||= AnyEvent->timer (
		1310	after => $MAX_SIGNAL_LATENCY,
		1311	interval => $MAX_SIGNAL_LATENCY,
		1312	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1313	);
967	};	1314	}
968		1315
969	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1316	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
970	}	1317	}
971		1318
		1319	sub signal {
		1320	# probe for availability of Async::Interrupt
		1321	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1322	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1323
		1324	$HAVE_ASYNC_INTERRUPT = 1;
		1325	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1326	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1327
		1328	} else {
		1329	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1330
		1331	require Fcntl;
		1332
		1333	if (AnyEvent::WIN32) {
		1334	require AnyEvent::Util;
		1335
		1336	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1337	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1338	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1339	} else {
		1340	pipe $SIGPIPE_R, $SIGPIPE_W;
		1341	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1342	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1343
		1344	# not strictly required, as $^F is normally 2, but let's make sure...
		1345	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1346	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1347	}
		1348
		1349	$SIGPIPE_R
		1350	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1351
		1352	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1353	}
		1354
		1355	*signal = \&_signal;
		1356	&signal
		1357	}
		1358
972	sub AnyEvent::Base::Signal::DESTROY {	1359	sub AnyEvent::Base::signal::DESTROY {
973	my ($signal, $cb) = @{$_[0]};	1360	my ($signal, $cb) = @{$_[0]};
974		1361
		1362	undef $SIG_TW
		1363	unless --$SIG_COUNT;
		1364
975	delete $SIG_CB{$signal}{$cb};	1365	delete $SIG_CB{$signal}{$cb};
976		1366
977	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };	1367	# delete doesn't work with older perls - they then
		1368	# print weird messages, or just unconditionally exit
		1369	# instead of getting the default action.
		1370	undef $SIG{$signal}
		1371	unless keys %{ $SIG_CB{$signal} };
978	}	1372	}
979		1373
980	# default implementation for ->child	1374	# default implementation for ->child
981		1375
982	our %PID_CB;	1376	our %PID_CB;
983	our $CHLD_W;	1377	our $CHLD_W;
984	our $CHLD_DELAY_W;	1378	our $CHLD_DELAY_W;
985	our $PID_IDLE;
986	our $WNOHANG;	1379	our $WNOHANG;
987		1380
988	sub _child_wait {	1381	sub _sigchld {
989	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1382	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1383	$_->($pid, $?)
990	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1384	for values %{ $PID_CB{$pid} || {} },
991	(values %{ $PID_CB{0} || {} });	1385	values %{ $PID_CB{0} || {} };
992	}	1386	}
993
994	undef $PID_IDLE;
995	}
996
997	sub _sigchld {
998	# make sure we deliver these changes "synchronous" with the event loop.
999	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1000	undef $CHLD_DELAY_W;
1001	&_child_wait;
1002	});
1003	}	1387	}
1004		1388
1005	sub child {	1389	sub child {
1006	my (undef, %arg) = @_;	1390	my (undef, %arg) = @_;
1007		1391
1008	defined (my $pid = $arg{pid} + 0)	1392	defined (my $pid = $arg{pid} + 0)
1009	or Carp::croak "required option 'pid' is missing";	1393	or Carp::croak "required option 'pid' is missing";
1010		1394
1011	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1395	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1012		1396
1013	unless ($WNOHANG) {	1397	# WNOHANG is almost cetrainly 1 everywhere
		1398	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1399	? 1
1014	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1400	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1015	}
1016		1401
1017	unless ($CHLD_W) {	1402	unless ($CHLD_W) {
1018	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1403	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1019	# child could be a zombie already, so make at least one round	1404	# child could be a zombie already, so make at least one round
1020	&_sigchld;	1405	&_sigchld;
1021	}	1406	}
1022		1407
1023	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1408	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1024	}	1409	}
1025		1410
1026	sub AnyEvent::Base::Child::DESTROY {	1411	sub AnyEvent::Base::child::DESTROY {
1027	my ($pid, $cb) = @{$_[0]};	1412	my ($pid, $cb) = @{$_[0]};
1028		1413
1029	delete $PID_CB{$pid}{$cb};	1414	delete $PID_CB{$pid}{$cb};
1030	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1415	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1031		1416
1032	undef $CHLD_W unless keys %PID_CB;	1417	undef $CHLD_W unless keys %PID_CB;
1033	}	1418	}
1034		1419
		1420	# idle emulation is done by simply using a timer, regardless
		1421	# of whether the process is idle or not, and not letting
		1422	# the callback use more than 50% of the time.
		1423	sub idle {
		1424	my (undef, %arg) = @_;
		1425
		1426	my ($cb, $w, $rcb) = $arg{cb};
		1427
		1428	$rcb = sub {
		1429	if ($cb) {
		1430	$w = _time;
		1431	&$cb;
		1432	$w = _time - $w;
		1433
		1434	# never use more then 50% of the time for the idle watcher,
		1435	# within some limits
		1436	$w = 0.0001 if $w < 0.0001;
		1437	$w = 5 if $w > 5;
		1438
		1439	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1440	} else {
		1441	# clean up...
		1442	undef $w;
		1443	undef $rcb;
		1444	}
		1445	};
		1446
		1447	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1448
		1449	bless \\$cb, "AnyEvent::Base::idle"
		1450	}
		1451
		1452	sub AnyEvent::Base::idle::DESTROY {
		1453	undef $${$_[0]};
		1454	}
		1455
1035	package AnyEvent::CondVar;	1456	package AnyEvent::CondVar;
1036		1457
1037	our @ISA = AnyEvent::CondVar::Base::;	1458	our @ISA = AnyEvent::CondVar::Base::;
1038		1459
1039	package AnyEvent::CondVar::Base;	1460	package AnyEvent::CondVar::Base;
1040		1461
1041	use overload	1462	#use overload
1042	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1463	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1043	fallback => 1;	1464	# fallback => 1;
		1465
		1466	# save 300+ kilobytes by dirtily hardcoding overloading
		1467	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1468	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1469	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1470	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1471
		1472	our $WAITING;
1044		1473
1045	sub _send {	1474	sub _send {
1046	# nop	1475	# nop
1047	}	1476	}
1048		1477
…		…
1061	sub ready {	1490	sub ready {
1062	$_[0]{_ae_sent}	1491	$_[0]{_ae_sent}
1063	}	1492	}
1064		1493
1065	sub _wait {	1494	sub _wait {
		1495	$WAITING
		1496	and !$_[0]{_ae_sent}
		1497	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1498
		1499	local $WAITING = 1;
1066	AnyEvent->one_event while !$_[0]{_ae_sent};	1500	AnyEvent->one_event while !$_[0]{_ae_sent};
1067	}	1501	}
1068		1502
1069	sub recv {	1503	sub recv {
1070	$_[0]->_wait;	1504	$_[0]->_wait;
…		…
1089	}	1523	}
1090		1524
1091	# undocumented/compatibility with pre-3.4	1525	# undocumented/compatibility with pre-3.4
1092	*broadcast = \&send;	1526	*broadcast = \&send;
1093	*wait = \&_wait;	1527	*wait = \&_wait;
		1528
		1529	=head1 ERROR AND EXCEPTION HANDLING
		1530
		1531	In general, AnyEvent does not do any error handling - it relies on the
		1532	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1533	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1534	checking of all AnyEvent methods, however, which is highly useful during
		1535	development.
		1536
		1537	As for exception handling (i.e. runtime errors and exceptions thrown while
		1538	executing a callback), this is not only highly event-loop specific, but
		1539	also not in any way wrapped by this module, as this is the job of the main
		1540	program.
		1541
		1542	The pure perl event loop simply re-throws the exception (usually
		1543	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1544	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1545	so on.
		1546
		1547	=head1 ENVIRONMENT VARIABLES
		1548
		1549	The following environment variables are used by this module or its
		1550	submodules.
		1551
		1552	Note that AnyEvent will remove I<all> environment variables starting with
		1553	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1554	enabled.
		1555
		1556	=over 4
		1557
		1558	=item C<PERL_ANYEVENT_VERBOSE>
		1559
		1560	By default, AnyEvent will be completely silent except in fatal
		1561	conditions. You can set this environment variable to make AnyEvent more
		1562	talkative.
		1563
		1564	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1565	conditions, such as not being able to load the event model specified by
		1566	C<PERL_ANYEVENT_MODEL>.
		1567
		1568	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1569	model it chooses.
		1570
		1571	When set to C<8> or higher, then AnyEvent will report extra information on
		1572	which optional modules it loads and how it implements certain features.
		1573
		1574	=item C<PERL_ANYEVENT_STRICT>
		1575
		1576	AnyEvent does not do much argument checking by default, as thorough
		1577	argument checking is very costly. Setting this variable to a true value
		1578	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1579	check the arguments passed to most method calls. If it finds any problems,
		1580	it will croak.
		1581
		1582	In other words, enables "strict" mode.
		1583
		1584	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1585	>>, it is definitely recommended to keep it off in production. Keeping
		1586	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1587	can be very useful, however.
		1588
		1589	=item C<PERL_ANYEVENT_MODEL>
		1590
		1591	This can be used to specify the event model to be used by AnyEvent, before
		1592	auto detection and -probing kicks in. It must be a string consisting
		1593	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1594	and the resulting module name is loaded and if the load was successful,
		1595	used as event model. If it fails to load AnyEvent will proceed with
		1596	auto detection and -probing.
		1597
		1598	This functionality might change in future versions.
		1599
		1600	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1601	could start your program like this:
		1602
		1603	PERL_ANYEVENT_MODEL=Perl perl ...
		1604
		1605	=item C<PERL_ANYEVENT_PROTOCOLS>
		1606
		1607	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1608	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1609	of auto probing).
		1610
		1611	Must be set to a comma-separated list of protocols or address families,
		1612	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1613	used, and preference will be given to protocols mentioned earlier in the
		1614	list.
		1615
		1616	This variable can effectively be used for denial-of-service attacks
		1617	against local programs (e.g. when setuid), although the impact is likely
		1618	small, as the program has to handle conenction and other failures anyways.
		1619
		1620	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1621	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1622	- only support IPv4, never try to resolve or contact IPv6
		1623	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1624	IPv6, but prefer IPv6 over IPv4.
		1625
		1626	=item C<PERL_ANYEVENT_EDNS0>
		1627
		1628	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1629	for DNS. This extension is generally useful to reduce DNS traffic, but
		1630	some (broken) firewalls drop such DNS packets, which is why it is off by
		1631	default.
		1632
		1633	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1634	EDNS0 in its DNS requests.
		1635
		1636	=item C<PERL_ANYEVENT_MAX_FORKS>
		1637
		1638	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1639	will create in parallel.
		1640
		1641	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1642
		1643	The default value for the C<max_outstanding> parameter for the default DNS
		1644	resolver - this is the maximum number of parallel DNS requests that are
		1645	sent to the DNS server.
		1646
		1647	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1648
		1649	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1650	configuration) in the default resolver. When set to the empty string, no
		1651	default config will be used.
		1652
		1653	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1654
		1655	When neither C<ca_file> nor C<ca_path> was specified during
		1656	L<AnyEvent::TLS> context creation, and either of these environment
		1657	variables exist, they will be used to specify CA certificate locations
		1658	instead of a system-dependent default.
		1659
		1660	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1661
		1662	When these are set to C<1>, then the respective modules are not
		1663	loaded. Mostly good for testing AnyEvent itself.
		1664
		1665	=back
1094		1666
1095	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1667	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1096		1668
1097	This is an advanced topic that you do not normally need to use AnyEvent in	1669	This is an advanced topic that you do not normally need to use AnyEvent in
1098	a module. This section is only of use to event loop authors who want to	1670	a module. This section is only of use to event loop authors who want to
…		…
1132		1704
1133	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1705	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1134	condition variables: code blocking while waiting for a condition will	1706	condition variables: code blocking while waiting for a condition will
1135	C<die>. This still works with most modules/usages, and blocking calls must	1707	C<die>. This still works with most modules/usages, and blocking calls must
1136	not be done in an interactive application, so it makes sense.	1708	not be done in an interactive application, so it makes sense.
1137
1138	=head1 ENVIRONMENT VARIABLES
1139
1140	The following environment variables are used by this module:
1141
1142	=over 4
1143
1144	=item C<PERL_ANYEVENT_VERBOSE>
1145
1146	By default, AnyEvent will be completely silent except in fatal
1147	conditions. You can set this environment variable to make AnyEvent more
1148	talkative.
1149
1150	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1151	conditions, such as not being able to load the event model specified by
1152	C<PERL_ANYEVENT_MODEL>.
1153
1154	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1155	model it chooses.
1156
1157	=item C<PERL_ANYEVENT_MODEL>
1158
1159	This can be used to specify the event model to be used by AnyEvent, before
1160	auto detection and -probing kicks in. It must be a string consisting
1161	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1162	and the resulting module name is loaded and if the load was successful,
1163	used as event model. If it fails to load AnyEvent will proceed with
1164	auto detection and -probing.
1165
1166	This functionality might change in future versions.
1167
1168	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1169	could start your program like this:
1170
1171	PERL_ANYEVENT_MODEL=Perl perl ...
1172
1173	=item C<PERL_ANYEVENT_PROTOCOLS>
1174
1175	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1176	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1177	of auto probing).
1178
1179	Must be set to a comma-separated list of protocols or address families,
1180	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1181	used, and preference will be given to protocols mentioned earlier in the
1182	list.
1183
1184	This variable can effectively be used for denial-of-service attacks
1185	against local programs (e.g. when setuid), although the impact is likely
1186	small, as the program has to handle connection errors already-
1187
1188	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1189	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1190	- only support IPv4, never try to resolve or contact IPv6
1191	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1192	IPv6, but prefer IPv6 over IPv4.
1193
1194	=item C<PERL_ANYEVENT_EDNS0>
1195
1196	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1197	for DNS. This extension is generally useful to reduce DNS traffic, but
1198	some (broken) firewalls drop such DNS packets, which is why it is off by
1199	default.
1200
1201	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1202	EDNS0 in its DNS requests.
1203
1204	=item C<PERL_ANYEVENT_MAX_FORKS>
1205
1206	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1207	will create in parallel.
1208
1209	=back
1210		1709
1211	=head1 EXAMPLE PROGRAM	1710	=head1 EXAMPLE PROGRAM
1212		1711
1213	The following program uses an I/O watcher to read data from STDIN, a timer	1712	The following program uses an I/O watcher to read data from STDIN, a timer
1214	to display a message once per second, and a condition variable to quit the	1713	to display a message once per second, and a condition variable to quit the
…		…
1408	watcher.	1907	watcher.
1409		1908
1410	=head3 Results	1909	=head3 Results
1411		1910
1412	name watchers bytes create invoke destroy comment	1911	name watchers bytes create invoke destroy comment
1413	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1912	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1414	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1913	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1415	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1914	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1416	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1915	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1417	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1916	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1418	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1917	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1918	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1919	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1419	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1920	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1420	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1921	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1421	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1922	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1422	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1923	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1423		1924
1424	=head3 Discussion	1925	=head3 Discussion
1425		1926
1426	The benchmark does I<not> measure scalability of the event loop very	1927	The benchmark does I<not> measure scalability of the event loop very
1427	well. For example, a select-based event loop (such as the pure perl one)	1928	well. For example, a select-based event loop (such as the pure perl one)
…		…
1452	performance becomes really bad with lots of file descriptors (and few of	1953	performance becomes really bad with lots of file descriptors (and few of
1453	them active), of course, but this was not subject of this benchmark.	1954	them active), of course, but this was not subject of this benchmark.
1454		1955
1455	The C<Event> module has a relatively high setup and callback invocation	1956	The C<Event> module has a relatively high setup and callback invocation
1456	cost, but overall scores in on the third place.	1957	cost, but overall scores in on the third place.
		1958
		1959	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1960	when using its pure perl backend.
1457		1961
1458	C<Glib>'s memory usage is quite a bit higher, but it features a	1962	C<Glib>'s memory usage is quite a bit higher, but it features a
1459	faster callback invocation and overall ends up in the same class as	1963	faster callback invocation and overall ends up in the same class as
1460	C<Event>. However, Glib scales extremely badly, doubling the number of	1964	C<Event>. However, Glib scales extremely badly, doubling the number of
1461	watchers increases the processing time by more than a factor of four,	1965	watchers increases the processing time by more than a factor of four,
…		…
1539	it to another server. This includes deleting the old timeout and creating	2043	it to another server. This includes deleting the old timeout and creating
1540	a new one that moves the timeout into the future.	2044	a new one that moves the timeout into the future.
1541		2045
1542	=head3 Results	2046	=head3 Results
1543		2047
1544	name sockets create request	2048	name sockets create request
1545	EV 20000 69.01 11.16	2049	EV 20000 69.01 11.16
1546	Perl 20000 73.32 35.87	2050	Perl 20000 73.32 35.87
		2051	IOAsync 20000 157.00 98.14 epoll
		2052	IOAsync 20000 159.31 616.06 poll
1547	Event 20000 212.62 257.32	2053	Event 20000 212.62 257.32
1548	Glib 20000 651.16 1896.30	2054	Glib 20000 651.16 1896.30
1549	POE 20000 349.67 12317.24 uses POE::Loop::Event	2055	POE 20000 349.67 12317.24 uses POE::Loop::Event
1550		2056
1551	=head3 Discussion	2057	=head3 Discussion
1552		2058
1553	This benchmark I<does> measure scalability and overall performance of the	2059	This benchmark I<does> measure scalability and overall performance of the
1554	particular event loop.	2060	particular event loop.
…		…
1556	EV is again fastest. Since it is using epoll on my system, the setup time	2062	EV is again fastest. Since it is using epoll on my system, the setup time
1557	is relatively high, though.	2063	is relatively high, though.
1558		2064
1559	Perl surprisingly comes second. It is much faster than the C-based event	2065	Perl surprisingly comes second. It is much faster than the C-based event
1560	loops Event and Glib.	2066	loops Event and Glib.
		2067
		2068	IO::Async performs very well when using its epoll backend, and still quite
		2069	good compared to Glib when using its pure perl backend.
1561		2070
1562	Event suffers from high setup time as well (look at its code and you will	2071	Event suffers from high setup time as well (look at its code and you will
1563	understand why). Callback invocation also has a high overhead compared to	2072	understand why). Callback invocation also has a high overhead compared to
1564	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2073	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1565	uses select or poll in basically all documented configurations.	2074	uses select or poll in basically all documented configurations.
…		…
1628	=item * C-based event loops perform very well with small number of	2137	=item * C-based event loops perform very well with small number of
1629	watchers, as the management overhead dominates.	2138	watchers, as the management overhead dominates.
1630		2139
1631	=back	2140	=back
1632		2141
		2142	=head2 THE IO::Lambda BENCHMARK
		2143
		2144	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2145	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2146	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2147	shouldn't come as a surprise to anybody). As such, the benchmark is
		2148	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2149	very optimal. But how would AnyEvent compare when used without the extra
		2150	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2151
		2152	The benchmark itself creates an echo-server, and then, for 500 times,
		2153	connects to the echo server, sends a line, waits for the reply, and then
		2154	creates the next connection. This is a rather bad benchmark, as it doesn't
		2155	test the efficiency of the framework or much non-blocking I/O, but it is a
		2156	benchmark nevertheless.
		2157
		2158	name runtime
		2159	Lambda/select 0.330 sec
		2160	+ optimized 0.122 sec
		2161	Lambda/AnyEvent 0.327 sec
		2162	+ optimized 0.138 sec
		2163	Raw sockets/select 0.077 sec
		2164	POE/select, components 0.662 sec
		2165	POE/select, raw sockets 0.226 sec
		2166	POE/select, optimized 0.404 sec
		2167
		2168	AnyEvent/select/nb 0.085 sec
		2169	AnyEvent/EV/nb 0.068 sec
		2170	+state machine 0.134 sec
		2171
		2172	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2173	benchmarks actually make blocking connects and use 100% blocking I/O,
		2174	defeating the purpose of an event-based solution. All of the newly
		2175	written AnyEvent benchmarks use 100% non-blocking connects (using
		2176	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2177	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2178	generally require a lot more bookkeeping and event handling than blocking
		2179	connects (which involve a single syscall only).
		2180
		2181	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2182	offers similar expressive power as POE and IO::Lambda, using conventional
		2183	Perl syntax. This means that both the echo server and the client are 100%
		2184	non-blocking, further placing it at a disadvantage.
		2185
		2186	As you can see, the AnyEvent + EV combination even beats the
		2187	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2188	backend easily beats IO::Lambda and POE.
		2189
		2190	And even the 100% non-blocking version written using the high-level (and
		2191	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2192	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2193	in a non-blocking way.
		2194
		2195	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2196	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2197	part of the IO::lambda distribution and were used without any changes.
		2198
		2199
		2200	=head1 SIGNALS
		2201
		2202	AnyEvent currently installs handlers for these signals:
		2203
		2204	=over 4
		2205
		2206	=item SIGCHLD
		2207
		2208	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2209	emulation for event loops that do not support them natively. Also, some
		2210	event loops install a similar handler.
		2211
		2212	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2213	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2214
		2215	=item SIGPIPE
		2216
		2217	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2218	when AnyEvent gets loaded.
		2219
		2220	The rationale for this is that AnyEvent users usually do not really depend
		2221	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2222	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2223	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2224	some random socket.
		2225
		2226	The rationale for installing a no-op handler as opposed to ignoring it is
		2227	that this way, the handler will be restored to defaults on exec.
		2228
		2229	Feel free to install your own handler, or reset it to defaults.
		2230
		2231	=back
		2232
		2233	=cut
		2234
		2235	undef $SIG{CHLD}
		2236	if $SIG{CHLD} eq 'IGNORE';
		2237
		2238	$SIG{PIPE} = sub { }
		2239	unless defined $SIG{PIPE};
		2240
		2241	=head1 RECOMMENDED/OPTIONAL MODULES
		2242
		2243	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2244	it's built-in modules) are required to use it.
		2245
		2246	That does not mean that AnyEvent won't take advantage of some additional
		2247	modules if they are installed.
		2248
		2249	This section epxlains which additional modules will be used, and how they
		2250	affect AnyEvent's operetion.
		2251
		2252	=over 4
		2253
		2254	=item L<Async::Interrupt>
		2255
		2256	This slightly arcane module is used to implement fast signal handling: To
		2257	my knowledge, there is no way to do completely race-free and quick
		2258	signal handling in pure perl. To ensure that signals still get
		2259	delivered, AnyEvent will start an interval timer to wake up perl (and
		2260	catch the signals) with soemd elay (default is 10 seconds, look for
		2261	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2262
		2263	If this module is available, then it will be used to implement signal
		2264	catching, which means that signals will not be delayed, and the event loop
		2265	will not be interrupted regularly, which is more efficient (And good for
		2266	battery life on laptops).
		2267
		2268	This affects not just the pure-perl event loop, but also other event loops
		2269	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2270
		2271	=item L<EV>
		2272
		2273	This module isn't really "optional", as it is simply one of the backend
		2274	event loops that AnyEvent can use. However, it is simply the best event
		2275	loop available in terms of features, speed and stability: It supports
		2276	the AnyEvent API optimally, implements all the watcher types in XS, does
		2277	automatic timer adjustments even when no monotonic clock is available,
		2278	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2279	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2280	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2281
		2282	=item L<Guard>
		2283
		2284	The guard module, when used, will be used to implement
		2285	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2286	lot less memory), but otherwise doesn't affect guard operation much. It is
		2287	purely used for performance.
		2288
		2289	=item L<JSON> and L<JSON::XS>
		2290
		2291	This module is required when you want to read or write JSON data via
		2292	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2293	advantage of the ulta-high-speed L<JSON::XS> module when it is installed.
		2294
		2295	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2296	installed.
		2297
		2298	=item L<Net::SSLeay>
		2299
		2300	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2301	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2302	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2303
		2304	=item L<Time::HiRes>
		2305
		2306	This module is part of perl since release 5.008. It will be used when the
		2307	chosen event library does not come with a timing source on it's own. The
		2308	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2309	try to use a monotonic clock for timing stability.
		2310
		2311	=back
		2312
1633		2313
1634	=head1 FORK	2314	=head1 FORK
1635		2315
1636	Most event libraries are not fork-safe. The ones who are usually are	2316	Most event libraries are not fork-safe. The ones who are usually are
1637	because they rely on inefficient but fork-safe C<select> or C<poll>	2317	because they rely on inefficient but fork-safe C<select> or C<poll>
1638	calls. Only L<EV> is fully fork-aware.	2318	calls. Only L<EV> is fully fork-aware.
1639		2319
1640	If you have to fork, you must either do so I<before> creating your first	2320	If you have to fork, you must either do so I<before> creating your first
1641	watcher OR you must not use AnyEvent at all in the child.	2321	watcher OR you must not use AnyEvent at all in the child OR you must do
		2322	something completely out of the scope of AnyEvent.
1642		2323
1643		2324
1644	=head1 SECURITY CONSIDERATIONS	2325	=head1 SECURITY CONSIDERATIONS
1645		2326
1646	AnyEvent can be forced to load any event model via	2327	AnyEvent can be forced to load any event model via
…		…
1651	specified in the variable.	2332	specified in the variable.
1652		2333
1653	You can make AnyEvent completely ignore this variable by deleting it	2334	You can make AnyEvent completely ignore this variable by deleting it
1654	before the first watcher gets created, e.g. with a C<BEGIN> block:	2335	before the first watcher gets created, e.g. with a C<BEGIN> block:
1655		2336
1656	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }	2337	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
1657		2338
1658	use AnyEvent;	2339	use AnyEvent;
1659		2340
1660	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2341	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1661	be used to probe what backend is used and gain other information (which is	2342	be used to probe what backend is used and gain other information (which is
1662	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2343	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2344	$ENV{PERL_ANYEVENT_STRICT}.
		2345
		2346	Note that AnyEvent will remove I<all> environment variables starting with
		2347	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2348	enabled.
		2349
		2350
		2351	=head1 BUGS
		2352
		2353	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
		2354	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
		2355	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
		2356	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
		2357	pronounced).
1663		2358
1664		2359
1665	=head1 SEE ALSO	2360	=head1 SEE ALSO
1666		2361
1667	Utility functions: L<AnyEvent::Util>.	2362	Utility functions: L<AnyEvent::Util>.
…		…
1670	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2365	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1671		2366
1672	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2367	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1673	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2368	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1674	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2369	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1675	L<AnyEvent::Impl::POE>.	2370	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1676		2371
1677	Non-blocking file handles, sockets, TCP clients and	2372	Non-blocking file handles, sockets, TCP clients and
1678	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2373	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1679		2374
1680	Asynchronous DNS: L<AnyEvent::DNS>.	2375	Asynchronous DNS: L<AnyEvent::DNS>.
1681		2376
1682	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2377	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2378	L<Coro::Event>,
1683		2379
1684	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2380	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2381	L<AnyEvent::HTTP>.
1685		2382
1686		2383
1687	=head1 AUTHOR	2384	=head1 AUTHOR
1688		2385
1689	Marc Lehmann <schmorp@schmorp.de>	2386	Marc Lehmann <schmorp@schmorp.de>
1690	http://home.schmorp.de/	2387	http://home.schmorp.de/
1691		2388
1692	=cut	2389	=cut
1693		2390
1694	1	2391	1
1695		2392

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