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Revision 1.277 by root, Sun Aug 9 13:27:23 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - the DBI of event loop programming
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Irssi, rxvt-unicode, IO::Async, Qt
		6	and POE are various supported event loops/environments.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub {	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
22		39
23	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
24		41
25	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
27	L<AnyEvent::Intro> manpage.	44	L<AnyEvent::Intro> manpage.
		45
		46	=head1 SUPPORT
		47
		48	There is a mailinglist for discussing all things AnyEvent, and an IRC
		49	channel, too.
		50
		51	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		52	Repository>, at L<http://anyevent.schmorp.de>, for more info.
28		53
29	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
30		55
31	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
32	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
…		…
128	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
129	creating a watcher it will immediately "watch" for events and invoke the	154	creating a watcher it will immediately "watch" for events and invoke the
130	callback when the event occurs (of course, only when the event model	155	callback when the event occurs (of course, only when the event model
131	is in control).	156	is in control).
132		157
		158	Note that B<callbacks must not permanently change global variables>
		159	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		160	callbacks must not C<die> >>. The former is good programming practise in
		161	Perl and the latter stems from the fact that exception handling differs
		162	widely between event loops.
		163
133	To disable the watcher you have to destroy it (e.g. by setting the	164	To disable the watcher you have to destroy it (e.g. by setting the
134	variable you store it in to C<undef> or otherwise deleting all references	165	variable you store it in to C<undef> or otherwise deleting all references
135	to it).	166	to it).
136		167
137	All watchers are created by calling a method on the C<AnyEvent> class.	168	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
150	my variables are only visible after the statement in which they are	181	my variables are only visible after the statement in which they are
151	declared.	182	declared.
152		183
153	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
154		185
		186	$w = AnyEvent->io (
		187	fh => <filehandle_or_fileno>,
		188	poll => <"r" or "w">,
		189	cb => <callback>,
		190	);
		191
155	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	192	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
156	with the following mandatory key-value pairs as arguments:	193	with the following mandatory key-value pairs as arguments:
157		194
158	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	195	C<fh> is the Perl I<file handle> (or a naked file descriptor) to watch
159	(AnyEvent might or might not keep a reference to this file handle). C<poll>	196	for events (AnyEvent might or might not keep a reference to this file
		197	handle). Note that only file handles pointing to things for which
		198	non-blocking operation makes sense are allowed. This includes sockets,
		199	most character devices, pipes, fifos and so on, but not for example files
		200	or block devices.
		201
160	must be a string that is either C<r> or C<w>, which creates a watcher	202	C<poll> must be a string that is either C<r> or C<w>, which creates a
161	waiting for "r"eadable or "w"ritable events, respectively. C<cb> is the	203	watcher waiting for "r"eadable or "w"ritable events, respectively.
		204
162	callback to invoke each time the file handle becomes ready.	205	C<cb> is the callback to invoke each time the file handle becomes ready.
163		206
164	Although the callback might get passed parameters, their value and	207	Although the callback might get passed parameters, their value and
165	presence is undefined and you cannot rely on them. Portable AnyEvent	208	presence is undefined and you cannot rely on them. Portable AnyEvent
166	callbacks cannot use arguments passed to I/O watcher callbacks.	209	callbacks cannot use arguments passed to I/O watcher callbacks.
167		210
…		…
182	undef $w;	225	undef $w;
183	});	226	});
184		227
185	=head2 TIME WATCHERS	228	=head2 TIME WATCHERS
186		229
		230	$w = AnyEvent->timer (after => <seconds>, cb => <callback>);
		231
		232	$w = AnyEvent->timer (
		233	after => <fractional_seconds>,
		234	interval => <fractional_seconds>,
		235	cb => <callback>,
		236	);
		237
187	You can create a time watcher by calling the C<< AnyEvent->timer >>	238	You can create a time watcher by calling the C<< AnyEvent->timer >>
188	method with the following mandatory arguments:	239	method with the following mandatory arguments:
189		240
190	C<after> specifies after how many seconds (fractional values are	241	C<after> specifies after how many seconds (fractional values are
191	supported) the callback should be invoked. C<cb> is the callback to invoke	242	supported) the callback should be invoked. C<cb> is the callback to invoke
…		…
299	In either case, if you care (and in most cases, you don't), then you	350	In either case, if you care (and in most cases, you don't), then you
300	can get whatever behaviour you want with any event loop, by taking the	351	can get whatever behaviour you want with any event loop, by taking the
301	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	352	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
302	account.	353	account.
303		354
		355	=item AnyEvent->now_update
		356
		357	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		358	the current time for each loop iteration (see the discussion of L<<
		359	AnyEvent->now >>, above).
		360
		361	When a callback runs for a long time (or when the process sleeps), then
		362	this "current" time will differ substantially from the real time, which
		363	might affect timers and time-outs.
		364
		365	When this is the case, you can call this method, which will update the
		366	event loop's idea of "current time".
		367
		368	Note that updating the time I<might> cause some events to be handled.
		369
304	=back	370	=back
305		371
306	=head2 SIGNAL WATCHERS	372	=head2 SIGNAL WATCHERS
		373
		374	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
307		375
308	You can watch for signals using a signal watcher, C<signal> is the signal	376	You can watch for signals using a signal watcher, C<signal> is the signal
309	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl	377	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
310	callback to be invoked whenever a signal occurs.	378	callback to be invoked whenever a signal occurs.
311		379
…		…
317	invocation, and callback invocation will be synchronous. Synchronous means	385	invocation, and callback invocation will be synchronous. Synchronous means
318	that it might take a while until the signal gets handled by the process,	386	that it might take a while until the signal gets handled by the process,
319	but it is guaranteed not to interrupt any other callbacks.	387	but it is guaranteed not to interrupt any other callbacks.
320		388
321	The main advantage of using these watchers is that you can share a signal	389	The main advantage of using these watchers is that you can share a signal
322	between multiple watchers.	390	between multiple watchers, and AnyEvent will ensure that signals will not
		391	interrupt your program at bad times.
323		392
324	This watcher might use C<%SIG>, so programs overwriting those signals	393	This watcher might use C<%SIG> (depending on the event loop used),
325	directly will likely not work correctly.	394	so programs overwriting those signals directly will likely not work
		395	correctly.
326		396
327	Example: exit on SIGINT	397	Example: exit on SIGINT
328		398
329	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	399	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
330		400
		401	=head3 Signal Races, Delays and Workarounds
		402
		403	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		404	callbacks to signals in a generic way, which is a pity, as you cannot
		405	do race-free signal handling in perl, requiring C libraries for
		406	this. AnyEvent will try to do it's best, which means in some cases,
		407	signals will be delayed. The maximum time a signal might be delayed is
		408	specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
		409	variable can be changed only before the first signal watcher is created,
		410	and should be left alone otherwise. This variable determines how often
		411	AnyEvent polls for signals (in case a wake-up was missed). Higher values
		412	will cause fewer spurious wake-ups, which is better for power and CPU
		413	saving.
		414
		415	All these problems can be avoided by installing the optional
		416	L<Async::Interrupt> module, which works with most event loops. It will not
		417	work with inherently broken event loops such as L<Event> or L<Event::Lib>
		418	(and not with L<POE> currently, as POE does it's own workaround with
		419	one-second latency). For those, you just have to suffer the delays.
		420
331	=head2 CHILD PROCESS WATCHERS	421	=head2 CHILD PROCESS WATCHERS
332		422
		423	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		424
333	You can also watch on a child process exit and catch its exit status.	425	You can also watch on a child process exit and catch its exit status.
334		426
335	The child process is specified by the C<pid> argument (if set to C<0>, it	427	The child process is specified by the C<pid> argument (one some backends,
336	watches for any child process exit). The watcher will trigger as often	428	using C<0> watches for any child process exit, on others this will
337	as status change for the child are received. This works by installing a	429	croak). The watcher will be triggered only when the child process has
338	signal handler for C<SIGCHLD>. The callback will be called with the pid	430	finished and an exit status is available, not on any trace events
339	and exit status (as returned by waitpid), so unlike other watcher types,	431	(stopped/continued).
340	you I<can> rely on child watcher callback arguments.	432
		433	The callback will be called with the pid and exit status (as returned by
		434	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		435	callback arguments.
		436
		437	This watcher type works by installing a signal handler for C<SIGCHLD>,
		438	and since it cannot be shared, nothing else should use SIGCHLD or reap
		439	random child processes (waiting for specific child processes, e.g. inside
		440	C<system>, is just fine).
341		441
342	There is a slight catch to child watchers, however: you usually start them	442	There is a slight catch to child watchers, however: you usually start them
343	I<after> the child process was created, and this means the process could	443	I<after> the child process was created, and this means the process could
344	have exited already (and no SIGCHLD will be sent anymore).	444	have exited already (and no SIGCHLD will be sent anymore).
345		445
346	Not all event models handle this correctly (POE doesn't), but even for	446	Not all event models handle this correctly (neither POE nor IO::Async do,
		447	see their AnyEvent::Impl manpages for details), but even for event models
347	event models that I<do> handle this correctly, they usually need to be	448	that I<do> handle this correctly, they usually need to be loaded before
348	loaded before the process exits (i.e. before you fork in the first place).	449	the process exits (i.e. before you fork in the first place). AnyEvent's
		450	pure perl event loop handles all cases correctly regardless of when you
		451	start the watcher.
349		452
350	This means you cannot create a child watcher as the very first thing in an	453	This means you cannot create a child watcher as the very first
351	AnyEvent program, you I<have> to create at least one watcher before you	454	thing in an AnyEvent program, you I<have> to create at least one
352	C<fork> the child (alternatively, you can call C<AnyEvent::detect>).	455	watcher before you C<fork> the child (alternatively, you can call
		456	C<AnyEvent::detect>).
		457
		458	As most event loops do not support waiting for child events, they will be
		459	emulated by AnyEvent in most cases, in which the latency and race problems
		460	mentioned in the description of signal watchers apply.
353		461
354	Example: fork a process and wait for it	462	Example: fork a process and wait for it
355		463
356	my $done = AnyEvent->condvar;	464	my $done = AnyEvent->condvar;
357		465
…		…
367	);	475	);
368		476
369	# do something else, then wait for process exit	477	# do something else, then wait for process exit
370	$done->recv;	478	$done->recv;
371		479
		480	=head2 IDLE WATCHERS
		481
		482	$w = AnyEvent->idle (cb => <callback>);
		483
		484	Sometimes there is a need to do something, but it is not so important
		485	to do it instantly, but only when there is nothing better to do. This
		486	"nothing better to do" is usually defined to be "no other events need
		487	attention by the event loop".
		488
		489	Idle watchers ideally get invoked when the event loop has nothing
		490	better to do, just before it would block the process to wait for new
		491	events. Instead of blocking, the idle watcher is invoked.
		492
		493	Most event loops unfortunately do not really support idle watchers (only
		494	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		495	will simply call the callback "from time to time".
		496
		497	Example: read lines from STDIN, but only process them when the
		498	program is otherwise idle:
		499
		500	my @lines; # read data
		501	my $idle_w;
		502	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		503	push @lines, scalar <STDIN>;
		504
		505	# start an idle watcher, if not already done
		506	$idle_w ||= AnyEvent->idle (cb => sub {
		507	# handle only one line, when there are lines left
		508	if (my $line = shift @lines) {
		509	print "handled when idle: $line";
		510	} else {
		511	# otherwise disable the idle watcher again
		512	undef $idle_w;
		513	}
		514	});
		515	});
		516
372	=head2 CONDITION VARIABLES	517	=head2 CONDITION VARIABLES
		518
		519	$cv = AnyEvent->condvar;
		520
		521	$cv->send (<list>);
		522	my @res = $cv->recv;
373		523
374	If you are familiar with some event loops you will know that all of them	524	If you are familiar with some event loops you will know that all of them
375	require you to run some blocking "loop", "run" or similar function that	525	require you to run some blocking "loop", "run" or similar function that
376	will actively watch for new events and call your callbacks.	526	will actively watch for new events and call your callbacks.
377		527
378	AnyEvent is different, it expects somebody else to run the event loop and	528	AnyEvent is slightly different: it expects somebody else to run the event
379	will only block when necessary (usually when told by the user).	529	loop and will only block when necessary (usually when told by the user).
380		530
381	The instrument to do that is called a "condition variable", so called	531	The instrument to do that is called a "condition variable", so called
382	because they represent a condition that must become true.	532	because they represent a condition that must become true.
		533
		534	Now is probably a good time to look at the examples further below.
383		535
384	Condition variables can be created by calling the C<< AnyEvent->condvar	536	Condition variables can be created by calling the C<< AnyEvent->condvar
385	>> method, usually without arguments. The only argument pair allowed is	537	>> method, usually without arguments. The only argument pair allowed is
386	C<cb>, which specifies a callback to be called when the condition variable	538	C<cb>, which specifies a callback to be called when the condition variable
387	becomes true.	539	becomes true, with the condition variable as the first argument (but not
		540	the results).
388		541
389	After creation, the condition variable is "false" until it becomes "true"	542	After creation, the condition variable is "false" until it becomes "true"
390	by calling the C<send> method (or calling the condition variable as if it	543	by calling the C<send> method (or calling the condition variable as if it
391	were a callback, read about the caveats in the description for the C<<	544	were a callback, read about the caveats in the description for the C<<
392	->send >> method).	545	->send >> method).
…		…
394	Condition variables are similar to callbacks, except that you can	547	Condition variables are similar to callbacks, except that you can
395	optionally wait for them. They can also be called merge points - points	548	optionally wait for them. They can also be called merge points - points
396	in time where multiple outstanding events have been processed. And yet	549	in time where multiple outstanding events have been processed. And yet
397	another way to call them is transactions - each condition variable can be	550	another way to call them is transactions - each condition variable can be
398	used to represent a transaction, which finishes at some point and delivers	551	used to represent a transaction, which finishes at some point and delivers
399	a result.	552	a result. And yet some people know them as "futures" - a promise to
		553	compute/deliver something that you can wait for.
400		554
401	Condition variables are very useful to signal that something has finished,	555	Condition variables are very useful to signal that something has finished,
402	for example, if you write a module that does asynchronous http requests,	556	for example, if you write a module that does asynchronous http requests,
403	then a condition variable would be the ideal candidate to signal the	557	then a condition variable would be the ideal candidate to signal the
404	availability of results. The user can either act when the callback is	558	availability of results. The user can either act when the callback is
…		…
438	after => 1,	592	after => 1,
439	cb => sub { $result_ready->send },	593	cb => sub { $result_ready->send },
440	);	594	);
441		595
442	# this "blocks" (while handling events) till the callback	596	# this "blocks" (while handling events) till the callback
443	# calls send	597	# calls -<send
444	$result_ready->recv;	598	$result_ready->recv;
445		599
446	Example: wait for a timer, but take advantage of the fact that	600	Example: wait for a timer, but take advantage of the fact that condition
447	condition variables are also code references.	601	variables are also callable directly.
448		602
449	my $done = AnyEvent->condvar;	603	my $done = AnyEvent->condvar;
450	my $delay = AnyEvent->timer (after => 5, cb => $done);	604	my $delay = AnyEvent->timer (after => 5, cb => $done);
451	$done->recv;	605	$done->recv;
		606
		607	Example: Imagine an API that returns a condvar and doesn't support
		608	callbacks. This is how you make a synchronous call, for example from
		609	the main program:
		610
		611	use AnyEvent::CouchDB;
		612
		613	...
		614
		615	my @info = $couchdb->info->recv;
		616
		617	And this is how you would just set a callback to be called whenever the
		618	results are available:
		619
		620	$couchdb->info->cb (sub {
		621	my @info = $_[0]->recv;
		622	});
452		623
453	=head3 METHODS FOR PRODUCERS	624	=head3 METHODS FOR PRODUCERS
454		625
455	These methods should only be used by the producing side, i.e. the	626	These methods should only be used by the producing side, i.e. the
456	code/module that eventually sends the signal. Note that it is also	627	code/module that eventually sends the signal. Note that it is also
…		…
469	immediately from within send.	640	immediately from within send.
470		641
471	Any arguments passed to the C<send> call will be returned by all	642	Any arguments passed to the C<send> call will be returned by all
472	future C<< ->recv >> calls.	643	future C<< ->recv >> calls.
473		644
474	Condition variables are overloaded so one can call them directly	645	Condition variables are overloaded so one can call them directly (as if
475	(as a code reference). Calling them directly is the same as calling	646	they were a code reference). Calling them directly is the same as calling
476	C<send>. Note, however, that many C-based event loops do not handle	647	C<send>.
477	overloading, so as tempting as it may be, passing a condition variable
478	instead of a callback does not work. Both the pure perl and EV loops
479	support overloading, however, as well as all functions that use perl to
480	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
481	example).
482		648
483	=item $cv->croak ($error)	649	=item $cv->croak ($error)
484		650
485	Similar to send, but causes all call's to C<< ->recv >> to invoke	651	Similar to send, but causes all call's to C<< ->recv >> to invoke
486	C<Carp::croak> with the given error message/object/scalar.	652	C<Carp::croak> with the given error message/object/scalar.
487		653
488	This can be used to signal any errors to the condition variable	654	This can be used to signal any errors to the condition variable
489	user/consumer.	655	user/consumer. Doing it this way instead of calling C<croak> directly
		656	delays the error detetcion, but has the overwhelmign advantage that it
		657	diagnoses the error at the place where the result is expected, and not
		658	deep in some event clalback without connection to the actual code causing
		659	the problem.
490		660
491	=item $cv->begin ([group callback])	661	=item $cv->begin ([group callback])
492		662
493	=item $cv->end	663	=item $cv->end
494
495	These two methods are EXPERIMENTAL and MIGHT CHANGE.
496		664
497	These two methods can be used to combine many transactions/events into	665	These two methods can be used to combine many transactions/events into
498	one. For example, a function that pings many hosts in parallel might want	666	one. For example, a function that pings many hosts in parallel might want
499	to use a condition variable for the whole process.	667	to use a condition variable for the whole process.
500		668
…		…
502	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	670	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end
503	>>, the (last) callback passed to C<begin> will be executed. That callback	671	>>, the (last) callback passed to C<begin> will be executed. That callback
504	is I<supposed> to call C<< ->send >>, but that is not required. If no	672	is I<supposed> to call C<< ->send >>, but that is not required. If no
505	callback was set, C<send> will be called without any arguments.	673	callback was set, C<send> will be called without any arguments.
506		674
507	Let's clarify this with the ping example:	675	You can think of C<< $cv->send >> giving you an OR condition (one call
		676	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		677	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		678
		679	Let's start with a simple example: you have two I/O watchers (for example,
		680	STDOUT and STDERR for a program), and you want to wait for both streams to
		681	close before activating a condvar:
		682
		683	my $cv = AnyEvent->condvar;
		684
		685	$cv->begin; # first watcher
		686	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		687	defined sysread $fh1, my $buf, 4096
		688	or $cv->end;
		689	});
		690
		691	$cv->begin; # second watcher
		692	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		693	defined sysread $fh2, my $buf, 4096
		694	or $cv->end;
		695	});
		696
		697	$cv->recv;
		698
		699	This works because for every event source (EOF on file handle), there is
		700	one call to C<begin>, so the condvar waits for all calls to C<end> before
		701	sending.
		702
		703	The ping example mentioned above is slightly more complicated, as the
		704	there are results to be passwd back, and the number of tasks that are
		705	begung can potentially be zero:
508		706
509	my $cv = AnyEvent->condvar;	707	my $cv = AnyEvent->condvar;
510		708
511	my %result;	709	my %result;
512	$cv->begin (sub { $cv->send (\%result) });	710	$cv->begin (sub { $cv->send (\%result) });
…		…
532	loop, which serves two important purposes: first, it sets the callback	730	loop, which serves two important purposes: first, it sets the callback
533	to be called once the counter reaches C<0>, and second, it ensures that	731	to be called once the counter reaches C<0>, and second, it ensures that
534	C<send> is called even when C<no> hosts are being pinged (the loop	732	C<send> is called even when C<no> hosts are being pinged (the loop
535	doesn't execute once).	733	doesn't execute once).
536		734
537	This is the general pattern when you "fan out" into multiple subrequests:	735	This is the general pattern when you "fan out" into multiple (but
538	use an outer C<begin>/C<end> pair to set the callback and ensure C<end>	736	potentially none) subrequests: use an outer C<begin>/C<end> pair to set
539	is called at least once, and then, for each subrequest you start, call	737	the callback and ensure C<end> is called at least once, and then, for each
540	C<begin> and for each subrequest you finish, call C<end>.	738	subrequest you start, call C<begin> and for each subrequest you finish,
		739	call C<end>.
541		740
542	=back	741	=back
543		742
544	=head3 METHODS FOR CONSUMERS	743	=head3 METHODS FOR CONSUMERS
545		744
…		…
561	function will call C<croak>.	760	function will call C<croak>.
562		761
563	In list context, all parameters passed to C<send> will be returned,	762	In list context, all parameters passed to C<send> will be returned,
564	in scalar context only the first one will be returned.	763	in scalar context only the first one will be returned.
565		764
		765	Note that doing a blocking wait in a callback is not supported by any
		766	event loop, that is, recursive invocation of a blocking C<< ->recv
		767	>> is not allowed, and the C<recv> call will C<croak> if such a
		768	condition is detected. This condition can be slightly loosened by using
		769	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		770	any thread that doesn't run the event loop itself.
		771
566	Not all event models support a blocking wait - some die in that case	772	Not all event models support a blocking wait - some die in that case
567	(programs might want to do that to stay interactive), so I<if you are	773	(programs might want to do that to stay interactive), so I<if you are
568	using this from a module, never require a blocking wait>, but let the	774	using this from a module, never require a blocking wait>. Instead, let the
569	caller decide whether the call will block or not (for example, by coupling	775	caller decide whether the call will block or not (for example, by coupling
570	condition variables with some kind of request results and supporting	776	condition variables with some kind of request results and supporting
571	callbacks so the caller knows that getting the result will not block,	777	callbacks so the caller knows that getting the result will not block,
572	while still supporting blocking waits if the caller so desires).	778	while still supporting blocking waits if the caller so desires).
573		779
574	Another reason I<never> to C<< ->recv >> in a module is that you cannot
575	sensibly have two C<< ->recv >>'s in parallel, as that would require
576	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
577	can supply.
578
579	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
580	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
581	versions and also integrates coroutines into AnyEvent, making blocking
582	C<< ->recv >> calls perfectly safe as long as they are done from another
583	coroutine (one that doesn't run the event loop).
584
585	You can ensure that C<< -recv >> never blocks by setting a callback and	780	You can ensure that C<< -recv >> never blocks by setting a callback and
586	only calling C<< ->recv >> from within that callback (or at a later	781	only calling C<< ->recv >> from within that callback (or at a later
587	time). This will work even when the event loop does not support blocking	782	time). This will work even when the event loop does not support blocking
588	waits otherwise.	783	waits otherwise.
589		784
590	=item $bool = $cv->ready	785	=item $bool = $cv->ready
591		786
592	Returns true when the condition is "true", i.e. whether C<send> or	787	Returns true when the condition is "true", i.e. whether C<send> or
593	C<croak> have been called.	788	C<croak> have been called.
594		789
595	=item $cb = $cv->cb ([new callback])	790	=item $cb = $cv->cb ($cb->($cv))
596		791
597	This is a mutator function that returns the callback set and optionally	792	This is a mutator function that returns the callback set and optionally
598	replaces it before doing so.	793	replaces it before doing so.
599		794
600	The callback will be called when the condition becomes "true", i.e. when	795	The callback will be called when the condition becomes (or already was)
601	C<send> or C<croak> are called, with the only argument being the condition	796	"true", i.e. when C<send> or C<croak> are called (or were called), with
602	variable itself. Calling C<recv> inside the callback or at any later time	797	the only argument being the condition variable itself. Calling C<recv>
603	is guaranteed not to block.	798	inside the callback or at any later time is guaranteed not to block.
604		799
605	=back	800	=back
606		801
		802	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		803
		804	The available backend classes are (every class has its own manpage):
		805
		806	=over 4
		807
		808	=item Backends that are autoprobed when no other event loop can be found.
		809
		810	EV is the preferred backend when no other event loop seems to be in
		811	use. If EV is not installed, then AnyEvent will fall back to its own
		812	pure-perl implementation, which is available everywhere as it comes with
		813	AnyEvent itself.
		814
		815	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		816	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		817
		818	=item Backends that are transparently being picked up when they are used.
		819
		820	These will be used when they are currently loaded when the first watcher
		821	is created, in which case it is assumed that the application is using
		822	them. This means that AnyEvent will automatically pick the right backend
		823	when the main program loads an event module before anything starts to
		824	create watchers. Nothing special needs to be done by the main program.
		825
		826	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		827	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		828	AnyEvent::Impl::Tk based on Tk, very broken.
		829	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		830	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		831	AnyEvent::Impl::Irssi used when running within irssi.
		832
		833	=item Backends with special needs.
		834
		835	Qt requires the Qt::Application to be instantiated first, but will
		836	otherwise be picked up automatically. As long as the main program
		837	instantiates the application before any AnyEvent watchers are created,
		838	everything should just work.
		839
		840	AnyEvent::Impl::Qt based on Qt.
		841
		842	Support for IO::Async can only be partial, as it is too broken and
		843	architecturally limited to even support the AnyEvent API. It also
		844	is the only event loop that needs the loop to be set explicitly, so
		845	it can only be used by a main program knowing about AnyEvent. See
		846	L<AnyEvent::Impl::Async> for the gory details.
		847
		848	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		849
		850	=item Event loops that are indirectly supported via other backends.
		851
		852	Some event loops can be supported via other modules:
		853
		854	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		855
		856	B<WxWidgets> has no support for watching file handles. However, you can
		857	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		858	polls 20 times per second, which was considered to be too horrible to even
		859	consider for AnyEvent.
		860
		861	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		862	backend, so it can be supported through POE.
		863
		864	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		865	load L<POE> when detecting them, in the hope that POE will pick them up,
		866	in which case everything will be automatic.
		867
		868	=back
		869
607	=head1 GLOBAL VARIABLES AND FUNCTIONS	870	=head1 GLOBAL VARIABLES AND FUNCTIONS
608		871
		872	These are not normally required to use AnyEvent, but can be useful to
		873	write AnyEvent extension modules.
		874
609	=over 4	875	=over 4
610		876
611	=item $AnyEvent::MODEL	877	=item $AnyEvent::MODEL
612		878
613	Contains C<undef> until the first watcher is being created. Then it	879	Contains C<undef> until the first watcher is being created, before the
		880	backend has been autodetected.
		881
614	contains the event model that is being used, which is the name of the	882	Afterwards it contains the event model that is being used, which is the
615	Perl class implementing the model. This class is usually one of the	883	name of the Perl class implementing the model. This class is usually one
616	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	884	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
617	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	885	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
618		886	will be C<urxvt::anyevent>).
619	The known classes so far are:
620
621	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
622	AnyEvent::Impl::Event based on Event, second best choice.
623	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
624	AnyEvent::Impl::Glib based on Glib, third-best choice.
625	AnyEvent::Impl::Tk based on Tk, very bad choice.
626	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
627	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
628	AnyEvent::Impl::POE based on POE, not generic enough for full support.
629
630	There is no support for WxWidgets, as WxWidgets has no support for
631	watching file handles. However, you can use WxWidgets through the
632	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
633	second, which was considered to be too horrible to even consider for
634	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
635	it's adaptor.
636
637	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
638	autodetecting them.
639		887
640	=item AnyEvent::detect	888	=item AnyEvent::detect
641		889
642	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	890	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
643	if necessary. You should only call this function right before you would	891	if necessary. You should only call this function right before you would
644	have created an AnyEvent watcher anyway, that is, as late as possible at	892	have created an AnyEvent watcher anyway, that is, as late as possible at
645	runtime.	893	runtime, and not e.g. while initialising of your module.
		894
		895	If you need to do some initialisation before AnyEvent watchers are
		896	created, use C<post_detect>.
646		897
647	=item $guard = AnyEvent::post_detect { BLOCK }	898	=item $guard = AnyEvent::post_detect { BLOCK }
648		899
649	Arranges for the code block to be executed as soon as the event model is	900	Arranges for the code block to be executed as soon as the event model is
650	autodetected (or immediately if this has already happened).	901	autodetected (or immediately if this has already happened).
651		902
		903	The block will be executed I<after> the actual backend has been detected
		904	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		905	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		906	other initialisations - see the sources of L<AnyEvent::Strict> or
		907	L<AnyEvent::AIO> to see how this is used.
		908
		909	The most common usage is to create some global watchers, without forcing
		910	event module detection too early, for example, L<AnyEvent::AIO> creates
		911	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		912	avoid autodetecting the event module at load time.
		913
652	If called in scalar or list context, then it creates and returns an object	914	If called in scalar or list context, then it creates and returns an object
653	that automatically removes the callback again when it is destroyed. See	915	that automatically removes the callback again when it is destroyed (or
		916	C<undef> when the hook was immediately executed). See L<AnyEvent::AIO> for
654	L<Coro::BDB> for a case where this is useful.	917	a case where this is useful.
		918
		919	Example: Create a watcher for the IO::AIO module and store it in
		920	C<$WATCHER>. Only do so after the event loop is initialised, though.
		921
		922	our WATCHER;
		923
		924	my $guard = AnyEvent::post_detect {
		925	$WATCHER = AnyEvent->io (fh => IO::AIO::poll_fileno, poll => 'r', cb => \&IO::AIO::poll_cb);
		926	};
		927
		928	# the ||= is important in case post_detect immediately runs the block,
		929	# as to not clobber the newly-created watcher. assigning both watcher and
		930	# post_detect guard to the same variable has the advantage of users being
		931	# able to just C<undef $WATCHER> if the watcher causes them grief.
		932
		933	$WATCHER ||= $guard;
655		934
656	=item @AnyEvent::post_detect	935	=item @AnyEvent::post_detect
657		936
658	If there are any code references in this array (you can C<push> to it	937	If there are any code references in this array (you can C<push> to it
659	before or after loading AnyEvent), then they will called directly after	938	before or after loading AnyEvent), then they will called directly after
660	the event loop has been chosen.	939	the event loop has been chosen.
661		940
662	You should check C<$AnyEvent::MODEL> before adding to this array, though:	941	You should check C<$AnyEvent::MODEL> before adding to this array, though:
663	if it contains a true value then the event loop has already been detected,	942	if it is defined then the event loop has already been detected, and the
664	and the array will be ignored.	943	array will be ignored.
665		944
666	Best use C<AnyEvent::post_detect { BLOCK }> instead.	945	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		946	it,as it takes care of these details.
		947
		948	This variable is mainly useful for modules that can do something useful
		949	when AnyEvent is used and thus want to know when it is initialised, but do
		950	not need to even load it by default. This array provides the means to hook
		951	into AnyEvent passively, without loading it.
667		952
668	=back	953	=back
669		954
670	=head1 WHAT TO DO IN A MODULE	955	=head1 WHAT TO DO IN A MODULE
671		956
…		…
726		1011
727		1012
728	=head1 OTHER MODULES	1013	=head1 OTHER MODULES
729		1014
730	The following is a non-exhaustive list of additional modules that use	1015	The following is a non-exhaustive list of additional modules that use
731	AnyEvent and can therefore be mixed easily with other AnyEvent modules	1016	AnyEvent as a client and can therefore be mixed easily with other AnyEvent
732	in the same program. Some of the modules come with AnyEvent, some are	1017	modules and other event loops in the same program. Some of the modules
733	available via CPAN.	1018	come with AnyEvent, most are available via CPAN.
734		1019
735	=over 4	1020	=over 4
736		1021
737	=item L<AnyEvent::Util>	1022	=item L<AnyEvent::Util>
738		1023
…		…
747		1032
748	=item L<AnyEvent::Handle>	1033	=item L<AnyEvent::Handle>
749		1034
750	Provide read and write buffers, manages watchers for reads and writes,	1035	Provide read and write buffers, manages watchers for reads and writes,
751	supports raw and formatted I/O, I/O queued and fully transparent and	1036	supports raw and formatted I/O, I/O queued and fully transparent and
752	non-blocking SSL/TLS.	1037	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
753		1038
754	=item L<AnyEvent::DNS>	1039	=item L<AnyEvent::DNS>
755		1040
756	Provides rich asynchronous DNS resolver capabilities.	1041	Provides rich asynchronous DNS resolver capabilities.
757		1042
…		…
785		1070
786	=item L<AnyEvent::GPSD>	1071	=item L<AnyEvent::GPSD>
787		1072
788	A non-blocking interface to gpsd, a daemon delivering GPS information.	1073	A non-blocking interface to gpsd, a daemon delivering GPS information.
789		1074
		1075	=item L<AnyEvent::IRC>
		1076
		1077	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1078
		1079	=item L<AnyEvent::XMPP>
		1080
		1081	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1082	Net::XMPP2>.
		1083
790	=item L<AnyEvent::IGS>	1084	=item L<AnyEvent::IGS>
791		1085
792	A non-blocking interface to the Internet Go Server protocol (used by	1086	A non-blocking interface to the Internet Go Server protocol (used by
793	L<App::IGS>).	1087	L<App::IGS>).
794		1088
795	=item L<Net::IRC3>
796
797	AnyEvent based IRC client module family.
798
799	=item L<Net::XMPP2>
800
801	AnyEvent based XMPP (Jabber protocol) module family.
802
803	=item L<Net::FCP>	1089	=item L<Net::FCP>
804		1090
805	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1091	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
806	of AnyEvent.	1092	of AnyEvent.
807		1093
…		…
811		1097
812	=item L<Coro>	1098	=item L<Coro>
813		1099
814	Has special support for AnyEvent via L<Coro::AnyEvent>.	1100	Has special support for AnyEvent via L<Coro::AnyEvent>.
815		1101
816	=item L<IO::Lambda>
817
818	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
819
820	=back	1102	=back
821		1103
822	=cut	1104	=cut
823		1105
824	package AnyEvent;	1106	package AnyEvent;
825		1107
		1108	# basically a tuned-down version of common::sense
		1109	sub common_sense {
826	no warnings;	1110	# no warnings
827	use strict;	1111	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1112	# use strict vars subs
		1113	$^H |= 0x00000600;
		1114	}
828		1115
		1116	BEGIN { AnyEvent::common_sense }
		1117
829	use Carp;	1118	use Carp ();
830		1119
831	our $VERSION = 4.2;	1120	our $VERSION = 4.92;
832	our $MODEL;	1121	our $MODEL;
833		1122
834	our $AUTOLOAD;	1123	our $AUTOLOAD;
835	our @ISA;	1124	our @ISA;
836		1125
837	our @REGISTRY;	1126	our @REGISTRY;
838		1127
839	our $WIN32;	1128	our $WIN32;
840		1129
		1130	our $VERBOSE;
		1131
841	BEGIN {	1132	BEGIN {
842	my $win32 = ! ! ($^O =~ /mswin32/i);	1133	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
843	eval "sub WIN32(){ $win32 }";	1134	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
844	}
845		1135
		1136	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1137	if ${^TAINT};
		1138
846	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1139	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1140
		1141	}
		1142
		1143	our $MAX_SIGNAL_LATENCY = 10;
847		1144
848	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1145	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
849		1146
850	{	1147	{
851	my $idx;	1148	my $idx;
…		…
853	for reverse split /\s*,\s*/,	1150	for reverse split /\s*,\s*/,
854	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1151	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
855	}	1152	}
856		1153
857	my @models = (	1154	my @models = (
858	[EV:: => AnyEvent::Impl::EV::],	1155	[EV:: => AnyEvent::Impl::EV:: , 1],
859	[Event:: => AnyEvent::Impl::Event::],
860	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1156	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
861	# everything below here will not be autoprobed	1157	# everything below here will not (normally) be autoprobed
862	# as the pureperl backend should work everywhere	1158	# as the pureperl backend should work everywhere
863	# and is usually faster	1159	# and is usually faster
		1160	[Event:: => AnyEvent::Impl::Event::, 1],
		1161	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1162	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1163	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
864	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1164	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
865	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
866	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
867	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1165	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
868	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1166	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
869	[Wx:: => AnyEvent::Impl::POE::],	1167	[Wx:: => AnyEvent::Impl::POE::],
870	[Prima:: => AnyEvent::Impl::POE::],	1168	[Prima:: => AnyEvent::Impl::POE::],
		1169	# IO::Async is just too broken - we would need workarounds for its
		1170	# byzantine signal and broken child handling, among others.
		1171	# IO::Async is rather hard to detect, as it doesn't have any
		1172	# obvious default class.
		1173	[IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1174	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1175	[IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1176	[AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
871	);	1177	);
872		1178
873	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1179	our %method = map +($_ => 1),
		1180	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
874		1181
875	our @post_detect;	1182	our @post_detect;
876		1183
877	sub post_detect(&) {	1184	sub post_detect(&) {
878	my ($cb) = @_;	1185	my ($cb) = @_;
879		1186
880	if ($MODEL) {	1187	if ($MODEL) {
881	$cb->();	1188	$cb->();
882		1189
883	1	1190	undef
884	} else {	1191	} else {
885	push @post_detect, $cb;	1192	push @post_detect, $cb;
886		1193
887	defined wantarray	1194	defined wantarray
888	? bless \$cb, "AnyEvent::Util::PostDetect"	1195	? bless \$cb, "AnyEvent::Util::postdetect"
889	: ()	1196	: ()
890	}	1197	}
891	}	1198	}
892		1199
893	sub AnyEvent::Util::PostDetect::DESTROY {	1200	sub AnyEvent::Util::postdetect::DESTROY {
894	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1201	@post_detect = grep $_ != ${$_[0]}, @post_detect;
895	}	1202	}
896		1203
897	sub detect() {	1204	sub detect() {
898	unless ($MODEL) {	1205	unless ($MODEL) {
899	no strict 'refs';
900	local $SIG{__DIE__};	1206	local $SIG{__DIE__};
901		1207
902	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1208	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
903	my $model = "AnyEvent::Impl::$1";	1209	my $model = "AnyEvent::Impl::$1";
904	if (eval "require $model") {	1210	if (eval "require $model") {
905	$MODEL = $model;	1211	$MODEL = $model;
906	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1212	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
907	} else {	1213	} else {
908	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1214	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
909	}	1215	}
910	}	1216	}
911		1217
912	# check for already loaded models	1218	# check for already loaded models
913	unless ($MODEL) {	1219	unless ($MODEL) {
914	for (@REGISTRY, @models) {	1220	for (@REGISTRY, @models) {
915	my ($package, $model) = @$_;	1221	my ($package, $model) = @$_;
916	if (${"$package\::VERSION"} > 0) {	1222	if (${"$package\::VERSION"} > 0) {
917	if (eval "require $model") {	1223	if (eval "require $model") {
918	$MODEL = $model;	1224	$MODEL = $model;
919	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1225	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
920	last;	1226	last;
921	}	1227	}
922	}	1228	}
923	}	1229	}
924		1230
925	unless ($MODEL) {	1231	unless ($MODEL) {
926	# try to load a model	1232	# try to autoload a model
927
928	for (@REGISTRY, @models) {	1233	for (@REGISTRY, @models) {
929	my ($package, $model) = @$_;	1234	my ($package, $model, $autoload) = @$_;
		1235	if (
		1236	$autoload
930	if (eval "require $package"	1237	and eval "require $package"
931	and ${"$package\::VERSION"} > 0	1238	and ${"$package\::VERSION"} > 0
932	and eval "require $model") {	1239	and eval "require $model"
		1240	) {
933	$MODEL = $model;	1241	$MODEL = $model;
934	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1242	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
935	last;	1243	last;
936	}	1244	}
937	}	1245	}
938		1246
939	$MODEL	1247	$MODEL
940	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1248	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
941	}	1249	}
942	}	1250	}
943		1251
944	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1252	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
945		1253
…		…
955		1263
956	sub AUTOLOAD {	1264	sub AUTOLOAD {
957	(my $func = $AUTOLOAD) =~ s/.*://;	1265	(my $func = $AUTOLOAD) =~ s/.*://;
958		1266
959	$method{$func}	1267	$method{$func}
960	or croak "$func: not a valid method for AnyEvent objects";	1268	or Carp::croak "$func: not a valid method for AnyEvent objects";
961		1269
962	detect unless $MODEL;	1270	detect unless $MODEL;
963		1271
964	my $class = shift;	1272	my $class = shift;
965	$class->$func (@_);	1273	$class->$func (@_);
966	}	1274	}
967		1275
968	# utility function to dup a filehandle. this is used by many backends	1276	# utility function to dup a filehandle. this is used by many backends
969	# to support binding more than one watcher per filehandle (they usually	1277	# to support binding more than one watcher per filehandle (they usually
970	# allow only one watcher per fd, so we dup it to get a different one).	1278	# allow only one watcher per fd, so we dup it to get a different one).
971	sub _dupfh($$$$) {	1279	sub _dupfh($$;$$) {
972	my ($poll, $fh, $r, $w) = @_;	1280	my ($poll, $fh, $r, $w) = @_;
973		1281
974	require Fcntl;
975
976	# cygwin requires the fh mode to be matching, unix doesn't	1282	# cygwin requires the fh mode to be matching, unix doesn't
977	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1283	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
978	: $poll eq "w" ? ($w, ">")
979	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
980		1284
981	open my $fh2, "$mode&" . fileno $fh	1285	open my $fh2, $mode, $fh
982	or die "cannot dup() filehandle: $!";	1286	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
983		1287
984	# we assume CLOEXEC is already set by perl in all important cases	1288	# we assume CLOEXEC is already set by perl in all important cases
985		1289
986	($fh2, $rw)	1290	($fh2, $rw)
987	}	1291	}
988		1292
		1293	#############################################################################
		1294	# "new" API, currently only emulation of it
		1295	#############################################################################
		1296
		1297	package AE;
		1298
		1299	our $VERSION = $AnyEvent::VERSION;
		1300
		1301	sub io($$$) {
		1302	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1303	}
		1304
		1305	sub timer($$$) {
		1306	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1307	}
		1308
		1309	sub signal($$) {
		1310	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1311	}
		1312
		1313	sub child($$) {
		1314	AnyEvent->child (pid => $_[0], cb => $_[1])
		1315	}
		1316
		1317	sub idle($) {
		1318	AnyEvent->idle (cb => $_[0])
		1319	}
		1320
		1321	sub cv(;&) {
		1322	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1323	}
		1324
		1325	sub now() {
		1326	AnyEvent->now
		1327	}
		1328
		1329	sub now_update() {
		1330	AnyEvent->now_update
		1331	}
		1332
		1333	sub time() {
		1334	AnyEvent->time
		1335	}
		1336
989	package AnyEvent::Base;	1337	package AnyEvent::Base;
990		1338
991	# default implementation for now and time	1339	# default implementations for many methods
992		1340
993	use Time::HiRes ();	1341	sub _time {
		1342	# probe for availability of Time::HiRes
		1343	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1344	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1345	*_time = \&Time::HiRes::time;
		1346	# if (eval "use POSIX (); (POSIX::times())...
		1347	} else {
		1348	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1349	*_time = sub { time }; # epic fail
		1350	}
994		1351
995	sub time { Time::HiRes::time }	1352	&_time
996	sub now { Time::HiRes::time }	1353	}
		1354
		1355	sub time { _time }
		1356	sub now { _time }
		1357	sub now_update { }
997		1358
998	# default implementation for ->condvar	1359	# default implementation for ->condvar
999		1360
1000	sub condvar {	1361	sub condvar {
1001	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1362	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1002	}	1363	}
1003		1364
1004	# default implementation for ->signal	1365	# default implementation for ->signal
1005		1366
1006	our %SIG_CB;	1367	our $HAVE_ASYNC_INTERRUPT;
		1368
		1369	sub _have_async_interrupt() {
		1370	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1371	&& eval "use Async::Interrupt 1.0 (); 1")
		1372	unless defined $HAVE_ASYNC_INTERRUPT;
		1373
		1374	$HAVE_ASYNC_INTERRUPT
		1375	}
		1376
		1377	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1378	our (%SIG_ASY, %SIG_ASY_W);
		1379	our ($SIG_COUNT, $SIG_TW);
		1380
		1381	sub _signal_exec {
		1382	$HAVE_ASYNC_INTERRUPT
		1383	? $SIGPIPE_R->drain
		1384	: sysread $SIGPIPE_R, my $dummy, 9;
		1385
		1386	while (%SIG_EV) {
		1387	for (keys %SIG_EV) {
		1388	delete $SIG_EV{$_};
		1389	$_->() for values %{ $SIG_CB{$_} || {} };
		1390	}
		1391	}
		1392	}
		1393
		1394	# install a dummy wakeup watcher to reduce signal catching latency
		1395	sub _sig_add() {
		1396	unless ($SIG_COUNT++) {
		1397	# try to align timer on a full-second boundary, if possible
		1398	my $NOW = AE::now;
		1399
		1400	$SIG_TW = AE::timer
		1401	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1402	$MAX_SIGNAL_LATENCY,
		1403	sub { } # just for the PERL_ASYNC_CHECK
		1404	;
		1405	}
		1406	}
		1407
		1408	sub _sig_del {
		1409	undef $SIG_TW
		1410	unless --$SIG_COUNT;
		1411	}
		1412
		1413	our $_sig_name_init; $_sig_name_init = sub {
		1414	eval q{ # poor man's autoloading
		1415	undef $_sig_name_init;
		1416
		1417	if (_have_async_interrupt) {
		1418	*sig2num = \&Async::Interrupt::sig2num;
		1419	*sig2name = \&Async::Interrupt::sig2name;
		1420	} else {
		1421	require Config;
		1422
		1423	my %signame2num;
		1424	@signame2num{ split ' ', $Config::Config{sig_name} }
		1425	= split ' ', $Config::Config{sig_num};
		1426
		1427	my @signum2name;
		1428	@signum2name[values %signame2num] = keys %signame2num;
		1429
		1430	*sig2num = sub($) {
		1431	$_[0] > 0 ? shift : $signame2num{+shift}
		1432	};
		1433	*sig2name = sub ($) {
		1434	$_[0] > 0 ? $signum2name[+shift] : shift
		1435	};
		1436	}
		1437	};
		1438	die if $@;
		1439	};
		1440
		1441	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1442	sub sig2name($) { &$_sig_name_init; &sig2name }
1007		1443
1008	sub signal {	1444	sub signal {
		1445	eval q{ # poor man's autoloading {}
		1446	# probe for availability of Async::Interrupt
		1447	if (_have_async_interrupt) {
		1448	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1449
		1450	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1451	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1452
		1453	} else {
		1454	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1455
		1456	require Fcntl;
		1457
		1458	if (AnyEvent::WIN32) {
		1459	require AnyEvent::Util;
		1460
		1461	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1462	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1463	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1464	} else {
		1465	pipe $SIGPIPE_R, $SIGPIPE_W;
		1466	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1467	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1468
		1469	# not strictly required, as $^F is normally 2, but let's make sure...
		1470	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1471	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1472	}
		1473
		1474	$SIGPIPE_R
		1475	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1476
		1477	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1478	}
		1479
		1480	*signal = sub {
1009	my (undef, %arg) = @_;	1481	my (undef, %arg) = @_;
1010		1482
1011	my $signal = uc $arg{signal}	1483	my $signal = uc $arg{signal}
1012	or Carp::croak "required option 'signal' is missing";	1484	or Carp::croak "required option 'signal' is missing";
1013		1485
		1486	if ($HAVE_ASYNC_INTERRUPT) {
		1487	# async::interrupt
		1488
		1489	$signal = sig2num $signal;
1014	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1490	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1491
		1492	$SIG_ASY{$signal} ||= new Async::Interrupt
		1493	cb => sub { undef $SIG_EV{$signal} },
		1494	signal => $signal,
		1495	pipe => [$SIGPIPE_R->filenos],
		1496	pipe_autodrain => 0,
		1497	;
		1498
		1499	} else {
		1500	# pure perl
		1501
		1502	# AE::Util has been loaded in signal
		1503	$signal = sig2name $signal;
		1504	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1505
1015	$SIG{$signal} ||= sub {	1506	$SIG{$signal} ||= sub {
1016	$_->() for values %{ $SIG_CB{$signal} || {} };	1507	local $!;
		1508	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1509	undef $SIG_EV{$signal};
		1510	};
		1511
		1512	# can't do signal processing without introducing races in pure perl,
		1513	# so limit the signal latency.
		1514	_sig_add;
		1515	}
		1516
		1517	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1518	};
		1519
		1520	*AnyEvent::Base::signal::DESTROY = sub {
		1521	my ($signal, $cb) = @{$_[0]};
		1522
		1523	_sig_del;
		1524
		1525	delete $SIG_CB{$signal}{$cb};
		1526
		1527	$HAVE_ASYNC_INTERRUPT
		1528	? delete $SIG_ASY{$signal}
		1529	: # delete doesn't work with older perls - they then
		1530	# print weird messages, or just unconditionally exit
		1531	# instead of getting the default action.
		1532	undef $SIG{$signal}
		1533	unless keys %{ $SIG_CB{$signal} };
		1534	};
1017	};	1535	};
1018		1536	die if $@;
1019	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1537	&signal
1020	}
1021
1022	sub AnyEvent::Base::Signal::DESTROY {
1023	my ($signal, $cb) = @{$_[0]};
1024
1025	delete $SIG_CB{$signal}{$cb};
1026
1027	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1028	}	1538	}
1029		1539
1030	# default implementation for ->child	1540	# default implementation for ->child
1031		1541
1032	our %PID_CB;	1542	our %PID_CB;
1033	our $CHLD_W;	1543	our $CHLD_W;
1034	our $CHLD_DELAY_W;	1544	our $CHLD_DELAY_W;
1035	our $PID_IDLE;
1036	our $WNOHANG;	1545	our $WNOHANG;
1037		1546
1038	sub _child_wait {	1547	sub _emit_childstatus($$) {
1039	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1548	my (undef, $rpid, $rstatus) = @_;
		1549
		1550	$_->($rpid, $rstatus)
1040	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1551	for values %{ $PID_CB{$rpid} || {} },
1041	(values %{ $PID_CB{0} || {} });	1552	values %{ $PID_CB{0} || {} };
1042	}
1043
1044	undef $PID_IDLE;
1045	}	1553	}
1046		1554
1047	sub _sigchld {	1555	sub _sigchld {
1048	# make sure we deliver these changes "synchronous" with the event loop.	1556	my $pid;
1049	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1557
1050	undef $CHLD_DELAY_W;	1558	AnyEvent->_emit_childstatus ($pid, $?)
1051	&_child_wait;	1559	while ($pid = waitpid -1, $WNOHANG) > 0;
1052	});
1053	}	1560	}
1054		1561
1055	sub child {	1562	sub child {
1056	my (undef, %arg) = @_;	1563	my (undef, %arg) = @_;
1057		1564
1058	defined (my $pid = $arg{pid} + 0)	1565	defined (my $pid = $arg{pid} + 0)
1059	or Carp::croak "required option 'pid' is missing";	1566	or Carp::croak "required option 'pid' is missing";
1060		1567
1061	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1568	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1062		1569
1063	unless ($WNOHANG) {	1570	# WNOHANG is almost cetrainly 1 everywhere
		1571	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1572	? 1
1064	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1573	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1065	}
1066		1574
1067	unless ($CHLD_W) {	1575	unless ($CHLD_W) {
1068	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1576	$CHLD_W = AE::signal CHLD => \&_sigchld;
1069	# child could be a zombie already, so make at least one round	1577	# child could be a zombie already, so make at least one round
1070	&_sigchld;	1578	&_sigchld;
1071	}	1579	}
1072		1580
1073	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1581	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1074	}	1582	}
1075		1583
1076	sub AnyEvent::Base::Child::DESTROY {	1584	sub AnyEvent::Base::child::DESTROY {
1077	my ($pid, $cb) = @{$_[0]};	1585	my ($pid, $cb) = @{$_[0]};
1078		1586
1079	delete $PID_CB{$pid}{$cb};	1587	delete $PID_CB{$pid}{$cb};
1080	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1588	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1081		1589
1082	undef $CHLD_W unless keys %PID_CB;	1590	undef $CHLD_W unless keys %PID_CB;
1083	}	1591	}
1084		1592
		1593	# idle emulation is done by simply using a timer, regardless
		1594	# of whether the process is idle or not, and not letting
		1595	# the callback use more than 50% of the time.
		1596	sub idle {
		1597	my (undef, %arg) = @_;
		1598
		1599	my ($cb, $w, $rcb) = $arg{cb};
		1600
		1601	$rcb = sub {
		1602	if ($cb) {
		1603	$w = _time;
		1604	&$cb;
		1605	$w = _time - $w;
		1606
		1607	# never use more then 50% of the time for the idle watcher,
		1608	# within some limits
		1609	$w = 0.0001 if $w < 0.0001;
		1610	$w = 5 if $w > 5;
		1611
		1612	$w = AE::timer $w, 0, $rcb;
		1613	} else {
		1614	# clean up...
		1615	undef $w;
		1616	undef $rcb;
		1617	}
		1618	};
		1619
		1620	$w = AE::timer 0.05, 0, $rcb;
		1621
		1622	bless \\$cb, "AnyEvent::Base::idle"
		1623	}
		1624
		1625	sub AnyEvent::Base::idle::DESTROY {
		1626	undef $${$_[0]};
		1627	}
		1628
1085	package AnyEvent::CondVar;	1629	package AnyEvent::CondVar;
1086		1630
1087	our @ISA = AnyEvent::CondVar::Base::;	1631	our @ISA = AnyEvent::CondVar::Base::;
1088		1632
1089	package AnyEvent::CondVar::Base;	1633	package AnyEvent::CondVar::Base;
1090		1634
1091	use overload	1635	#use overload
1092	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1636	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1093	fallback => 1;	1637	# fallback => 1;
		1638
		1639	# save 300+ kilobytes by dirtily hardcoding overloading
		1640	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1641	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1642	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1643	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1644
		1645	our $WAITING;
1094		1646
1095	sub _send {	1647	sub _send {
1096	# nop	1648	# nop
1097	}	1649	}
1098		1650
…		…
1111	sub ready {	1663	sub ready {
1112	$_[0]{_ae_sent}	1664	$_[0]{_ae_sent}
1113	}	1665	}
1114		1666
1115	sub _wait {	1667	sub _wait {
		1668	$WAITING
		1669	and !$_[0]{_ae_sent}
		1670	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1671
		1672	local $WAITING = 1;
1116	AnyEvent->one_event while !$_[0]{_ae_sent};	1673	AnyEvent->one_event while !$_[0]{_ae_sent};
1117	}	1674	}
1118		1675
1119	sub recv {	1676	sub recv {
1120	$_[0]->_wait;	1677	$_[0]->_wait;
…		…
1122	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1679	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1123	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1680	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1124	}	1681	}
1125		1682
1126	sub cb {	1683	sub cb {
1127	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1684	my $cv = shift;
		1685
		1686	@_
		1687	and $cv->{_ae_cb} = shift
		1688	and $cv->{_ae_sent}
		1689	and (delete $cv->{_ae_cb})->($cv);
		1690
1128	$_[0]{_ae_cb}	1691	$cv->{_ae_cb}
1129	}	1692	}
1130		1693
1131	sub begin {	1694	sub begin {
1132	++$_[0]{_ae_counter};	1695	++$_[0]{_ae_counter};
1133	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1696	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1139	}	1702	}
1140		1703
1141	# undocumented/compatibility with pre-3.4	1704	# undocumented/compatibility with pre-3.4
1142	*broadcast = \&send;	1705	*broadcast = \&send;
1143	*wait = \&_wait;	1706	*wait = \&_wait;
		1707
		1708	=head1 ERROR AND EXCEPTION HANDLING
		1709
		1710	In general, AnyEvent does not do any error handling - it relies on the
		1711	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1712	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1713	checking of all AnyEvent methods, however, which is highly useful during
		1714	development.
		1715
		1716	As for exception handling (i.e. runtime errors and exceptions thrown while
		1717	executing a callback), this is not only highly event-loop specific, but
		1718	also not in any way wrapped by this module, as this is the job of the main
		1719	program.
		1720
		1721	The pure perl event loop simply re-throws the exception (usually
		1722	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1723	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1724	so on.
		1725
		1726	=head1 ENVIRONMENT VARIABLES
		1727
		1728	The following environment variables are used by this module or its
		1729	submodules.
		1730
		1731	Note that AnyEvent will remove I<all> environment variables starting with
		1732	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1733	enabled.
		1734
		1735	=over 4
		1736
		1737	=item C<PERL_ANYEVENT_VERBOSE>
		1738
		1739	By default, AnyEvent will be completely silent except in fatal
		1740	conditions. You can set this environment variable to make AnyEvent more
		1741	talkative.
		1742
		1743	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1744	conditions, such as not being able to load the event model specified by
		1745	C<PERL_ANYEVENT_MODEL>.
		1746
		1747	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1748	model it chooses.
		1749
		1750	When set to C<8> or higher, then AnyEvent will report extra information on
		1751	which optional modules it loads and how it implements certain features.
		1752
		1753	=item C<PERL_ANYEVENT_STRICT>
		1754
		1755	AnyEvent does not do much argument checking by default, as thorough
		1756	argument checking is very costly. Setting this variable to a true value
		1757	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1758	check the arguments passed to most method calls. If it finds any problems,
		1759	it will croak.
		1760
		1761	In other words, enables "strict" mode.
		1762
		1763	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1764	>>, it is definitely recommended to keep it off in production. Keeping
		1765	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1766	can be very useful, however.
		1767
		1768	=item C<PERL_ANYEVENT_MODEL>
		1769
		1770	This can be used to specify the event model to be used by AnyEvent, before
		1771	auto detection and -probing kicks in. It must be a string consisting
		1772	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1773	and the resulting module name is loaded and if the load was successful,
		1774	used as event model. If it fails to load AnyEvent will proceed with
		1775	auto detection and -probing.
		1776
		1777	This functionality might change in future versions.
		1778
		1779	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1780	could start your program like this:
		1781
		1782	PERL_ANYEVENT_MODEL=Perl perl ...
		1783
		1784	=item C<PERL_ANYEVENT_PROTOCOLS>
		1785
		1786	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1787	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1788	of auto probing).
		1789
		1790	Must be set to a comma-separated list of protocols or address families,
		1791	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1792	used, and preference will be given to protocols mentioned earlier in the
		1793	list.
		1794
		1795	This variable can effectively be used for denial-of-service attacks
		1796	against local programs (e.g. when setuid), although the impact is likely
		1797	small, as the program has to handle conenction and other failures anyways.
		1798
		1799	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1800	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1801	- only support IPv4, never try to resolve or contact IPv6
		1802	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1803	IPv6, but prefer IPv6 over IPv4.
		1804
		1805	=item C<PERL_ANYEVENT_EDNS0>
		1806
		1807	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1808	for DNS. This extension is generally useful to reduce DNS traffic, but
		1809	some (broken) firewalls drop such DNS packets, which is why it is off by
		1810	default.
		1811
		1812	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1813	EDNS0 in its DNS requests.
		1814
		1815	=item C<PERL_ANYEVENT_MAX_FORKS>
		1816
		1817	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1818	will create in parallel.
		1819
		1820	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1821
		1822	The default value for the C<max_outstanding> parameter for the default DNS
		1823	resolver - this is the maximum number of parallel DNS requests that are
		1824	sent to the DNS server.
		1825
		1826	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1827
		1828	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1829	configuration) in the default resolver. When set to the empty string, no
		1830	default config will be used.
		1831
		1832	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1833
		1834	When neither C<ca_file> nor C<ca_path> was specified during
		1835	L<AnyEvent::TLS> context creation, and either of these environment
		1836	variables exist, they will be used to specify CA certificate locations
		1837	instead of a system-dependent default.
		1838
		1839	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1840
		1841	When these are set to C<1>, then the respective modules are not
		1842	loaded. Mostly good for testing AnyEvent itself.
		1843
		1844	=back
1144		1845
1145	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1846	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1146		1847
1147	This is an advanced topic that you do not normally need to use AnyEvent in	1848	This is an advanced topic that you do not normally need to use AnyEvent in
1148	a module. This section is only of use to event loop authors who want to	1849	a module. This section is only of use to event loop authors who want to
…		…
1182		1883
1183	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1884	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1184	condition variables: code blocking while waiting for a condition will	1885	condition variables: code blocking while waiting for a condition will
1185	C<die>. This still works with most modules/usages, and blocking calls must	1886	C<die>. This still works with most modules/usages, and blocking calls must
1186	not be done in an interactive application, so it makes sense.	1887	not be done in an interactive application, so it makes sense.
1187
1188	=head1 ENVIRONMENT VARIABLES
1189
1190	The following environment variables are used by this module:
1191
1192	=over 4
1193
1194	=item C<PERL_ANYEVENT_VERBOSE>
1195
1196	By default, AnyEvent will be completely silent except in fatal
1197	conditions. You can set this environment variable to make AnyEvent more
1198	talkative.
1199
1200	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1201	conditions, such as not being able to load the event model specified by
1202	C<PERL_ANYEVENT_MODEL>.
1203
1204	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1205	model it chooses.
1206
1207	=item C<PERL_ANYEVENT_STRICT>
1208
1209	AnyEvent does not do much argument checking by default, as thorough
1210	argument checking is very costly. Setting this variable to a true value
1211	will cause AnyEvent to thoroughly check the arguments passed to most
1212	method calls and croaks if it finds any problems. In other words, enables
1213	"strict" mode. Unlike C<use strict> it is definitely recommended ot keep
1214	it off in production.
1215
1216	=item C<PERL_ANYEVENT_MODEL>
1217
1218	This can be used to specify the event model to be used by AnyEvent, before
1219	auto detection and -probing kicks in. It must be a string consisting
1220	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1221	and the resulting module name is loaded and if the load was successful,
1222	used as event model. If it fails to load AnyEvent will proceed with
1223	auto detection and -probing.
1224
1225	This functionality might change in future versions.
1226
1227	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1228	could start your program like this:
1229
1230	PERL_ANYEVENT_MODEL=Perl perl ...
1231
1232	=item C<PERL_ANYEVENT_PROTOCOLS>
1233
1234	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1235	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1236	of auto probing).
1237
1238	Must be set to a comma-separated list of protocols or address families,
1239	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1240	used, and preference will be given to protocols mentioned earlier in the
1241	list.
1242
1243	This variable can effectively be used for denial-of-service attacks
1244	against local programs (e.g. when setuid), although the impact is likely
1245	small, as the program has to handle connection errors already-
1246
1247	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1248	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1249	- only support IPv4, never try to resolve or contact IPv6
1250	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1251	IPv6, but prefer IPv6 over IPv4.
1252
1253	=item C<PERL_ANYEVENT_EDNS0>
1254
1255	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1256	for DNS. This extension is generally useful to reduce DNS traffic, but
1257	some (broken) firewalls drop such DNS packets, which is why it is off by
1258	default.
1259
1260	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1261	EDNS0 in its DNS requests.
1262
1263	=item C<PERL_ANYEVENT_MAX_FORKS>
1264
1265	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1266	will create in parallel.
1267
1268	=back
1269		1888
1270	=head1 EXAMPLE PROGRAM	1889	=head1 EXAMPLE PROGRAM
1271		1890
1272	The following program uses an I/O watcher to read data from STDIN, a timer	1891	The following program uses an I/O watcher to read data from STDIN, a timer
1273	to display a message once per second, and a condition variable to quit the	1892	to display a message once per second, and a condition variable to quit the
…		…
1467	watcher.	2086	watcher.
1468		2087
1469	=head3 Results	2088	=head3 Results
1470		2089
1471	name watchers bytes create invoke destroy comment	2090	name watchers bytes create invoke destroy comment
1472	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2091	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1473	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2092	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1474	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2093	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1475	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2094	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1476	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2095	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1477	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2096	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		2097	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		2098	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1478	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2099	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1479	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2100	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1480	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2101	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1481	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2102	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1482		2103
1483	=head3 Discussion	2104	=head3 Discussion
1484		2105
1485	The benchmark does I<not> measure scalability of the event loop very	2106	The benchmark does I<not> measure scalability of the event loop very
1486	well. For example, a select-based event loop (such as the pure perl one)	2107	well. For example, a select-based event loop (such as the pure perl one)
…		…
1511	performance becomes really bad with lots of file descriptors (and few of	2132	performance becomes really bad with lots of file descriptors (and few of
1512	them active), of course, but this was not subject of this benchmark.	2133	them active), of course, but this was not subject of this benchmark.
1513		2134
1514	The C<Event> module has a relatively high setup and callback invocation	2135	The C<Event> module has a relatively high setup and callback invocation
1515	cost, but overall scores in on the third place.	2136	cost, but overall scores in on the third place.
		2137
		2138	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2139	when using its pure perl backend.
1516		2140
1517	C<Glib>'s memory usage is quite a bit higher, but it features a	2141	C<Glib>'s memory usage is quite a bit higher, but it features a
1518	faster callback invocation and overall ends up in the same class as	2142	faster callback invocation and overall ends up in the same class as
1519	C<Event>. However, Glib scales extremely badly, doubling the number of	2143	C<Event>. However, Glib scales extremely badly, doubling the number of
1520	watchers increases the processing time by more than a factor of four,	2144	watchers increases the processing time by more than a factor of four,
…		…
1598	it to another server. This includes deleting the old timeout and creating	2222	it to another server. This includes deleting the old timeout and creating
1599	a new one that moves the timeout into the future.	2223	a new one that moves the timeout into the future.
1600		2224
1601	=head3 Results	2225	=head3 Results
1602		2226
1603	name sockets create request	2227	name sockets create request
1604	EV 20000 69.01 11.16	2228	EV 20000 69.01 11.16
1605	Perl 20000 73.32 35.87	2229	Perl 20000 73.32 35.87
		2230	IOAsync 20000 157.00 98.14 epoll
		2231	IOAsync 20000 159.31 616.06 poll
1606	Event 20000 212.62 257.32	2232	Event 20000 212.62 257.32
1607	Glib 20000 651.16 1896.30	2233	Glib 20000 651.16 1896.30
1608	POE 20000 349.67 12317.24 uses POE::Loop::Event	2234	POE 20000 349.67 12317.24 uses POE::Loop::Event
1609		2235
1610	=head3 Discussion	2236	=head3 Discussion
1611		2237
1612	This benchmark I<does> measure scalability and overall performance of the	2238	This benchmark I<does> measure scalability and overall performance of the
1613	particular event loop.	2239	particular event loop.
…		…
1615	EV is again fastest. Since it is using epoll on my system, the setup time	2241	EV is again fastest. Since it is using epoll on my system, the setup time
1616	is relatively high, though.	2242	is relatively high, though.
1617		2243
1618	Perl surprisingly comes second. It is much faster than the C-based event	2244	Perl surprisingly comes second. It is much faster than the C-based event
1619	loops Event and Glib.	2245	loops Event and Glib.
		2246
		2247	IO::Async performs very well when using its epoll backend, and still quite
		2248	good compared to Glib when using its pure perl backend.
1620		2249
1621	Event suffers from high setup time as well (look at its code and you will	2250	Event suffers from high setup time as well (look at its code and you will
1622	understand why). Callback invocation also has a high overhead compared to	2251	understand why). Callback invocation also has a high overhead compared to
1623	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2252	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1624	uses select or poll in basically all documented configurations.	2253	uses select or poll in basically all documented configurations.
…		…
1687	=item * C-based event loops perform very well with small number of	2316	=item * C-based event loops perform very well with small number of
1688	watchers, as the management overhead dominates.	2317	watchers, as the management overhead dominates.
1689		2318
1690	=back	2319	=back
1691		2320
		2321	=head2 THE IO::Lambda BENCHMARK
		2322
		2323	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2324	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2325	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2326	shouldn't come as a surprise to anybody). As such, the benchmark is
		2327	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2328	very optimal. But how would AnyEvent compare when used without the extra
		2329	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2330
		2331	The benchmark itself creates an echo-server, and then, for 500 times,
		2332	connects to the echo server, sends a line, waits for the reply, and then
		2333	creates the next connection. This is a rather bad benchmark, as it doesn't
		2334	test the efficiency of the framework or much non-blocking I/O, but it is a
		2335	benchmark nevertheless.
		2336
		2337	name runtime
		2338	Lambda/select 0.330 sec
		2339	+ optimized 0.122 sec
		2340	Lambda/AnyEvent 0.327 sec
		2341	+ optimized 0.138 sec
		2342	Raw sockets/select 0.077 sec
		2343	POE/select, components 0.662 sec
		2344	POE/select, raw sockets 0.226 sec
		2345	POE/select, optimized 0.404 sec
		2346
		2347	AnyEvent/select/nb 0.085 sec
		2348	AnyEvent/EV/nb 0.068 sec
		2349	+state machine 0.134 sec
		2350
		2351	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2352	benchmarks actually make blocking connects and use 100% blocking I/O,
		2353	defeating the purpose of an event-based solution. All of the newly
		2354	written AnyEvent benchmarks use 100% non-blocking connects (using
		2355	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2356	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2357	generally require a lot more bookkeeping and event handling than blocking
		2358	connects (which involve a single syscall only).
		2359
		2360	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2361	offers similar expressive power as POE and IO::Lambda, using conventional
		2362	Perl syntax. This means that both the echo server and the client are 100%
		2363	non-blocking, further placing it at a disadvantage.
		2364
		2365	As you can see, the AnyEvent + EV combination even beats the
		2366	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2367	backend easily beats IO::Lambda and POE.
		2368
		2369	And even the 100% non-blocking version written using the high-level (and
		2370	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2371	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2372	in a non-blocking way.
		2373
		2374	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2375	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2376	part of the IO::lambda distribution and were used without any changes.
		2377
		2378
		2379	=head1 SIGNALS
		2380
		2381	AnyEvent currently installs handlers for these signals:
		2382
		2383	=over 4
		2384
		2385	=item SIGCHLD
		2386
		2387	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2388	emulation for event loops that do not support them natively. Also, some
		2389	event loops install a similar handler.
		2390
		2391	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2392	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2393
		2394	=item SIGPIPE
		2395
		2396	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2397	when AnyEvent gets loaded.
		2398
		2399	The rationale for this is that AnyEvent users usually do not really depend
		2400	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2401	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2402	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2403	some random socket.
		2404
		2405	The rationale for installing a no-op handler as opposed to ignoring it is
		2406	that this way, the handler will be restored to defaults on exec.
		2407
		2408	Feel free to install your own handler, or reset it to defaults.
		2409
		2410	=back
		2411
		2412	=cut
		2413
		2414	undef $SIG{CHLD}
		2415	if $SIG{CHLD} eq 'IGNORE';
		2416
		2417	$SIG{PIPE} = sub { }
		2418	unless defined $SIG{PIPE};
		2419
		2420	=head1 RECOMMENDED/OPTIONAL MODULES
		2421
		2422	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2423	it's built-in modules) are required to use it.
		2424
		2425	That does not mean that AnyEvent won't take advantage of some additional
		2426	modules if they are installed.
		2427
		2428	This section epxlains which additional modules will be used, and how they
		2429	affect AnyEvent's operetion.
		2430
		2431	=over 4
		2432
		2433	=item L<Async::Interrupt>
		2434
		2435	This slightly arcane module is used to implement fast signal handling: To
		2436	my knowledge, there is no way to do completely race-free and quick
		2437	signal handling in pure perl. To ensure that signals still get
		2438	delivered, AnyEvent will start an interval timer to wake up perl (and
		2439	catch the signals) with some delay (default is 10 seconds, look for
		2440	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2441
		2442	If this module is available, then it will be used to implement signal
		2443	catching, which means that signals will not be delayed, and the event loop
		2444	will not be interrupted regularly, which is more efficient (And good for
		2445	battery life on laptops).
		2446
		2447	This affects not just the pure-perl event loop, but also other event loops
		2448	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2449
		2450	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2451	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2452	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2453	does nothing for those backends.
		2454
		2455	=item L<EV>
		2456
		2457	This module isn't really "optional", as it is simply one of the backend
		2458	event loops that AnyEvent can use. However, it is simply the best event
		2459	loop available in terms of features, speed and stability: It supports
		2460	the AnyEvent API optimally, implements all the watcher types in XS, does
		2461	automatic timer adjustments even when no monotonic clock is available,
		2462	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2463	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2464	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2465
		2466	=item L<Guard>
		2467
		2468	The guard module, when used, will be used to implement
		2469	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2470	lot less memory), but otherwise doesn't affect guard operation much. It is
		2471	purely used for performance.
		2472
		2473	=item L<JSON> and L<JSON::XS>
		2474
		2475	This module is required when you want to read or write JSON data via
		2476	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2477	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2478
		2479	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2480	installed.
		2481
		2482	=item L<Net::SSLeay>
		2483
		2484	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2485	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2486	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2487
		2488	=item L<Time::HiRes>
		2489
		2490	This module is part of perl since release 5.008. It will be used when the
		2491	chosen event library does not come with a timing source on it's own. The
		2492	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2493	try to use a monotonic clock for timing stability.
		2494
		2495	=back
		2496
1692		2497
1693	=head1 FORK	2498	=head1 FORK
1694		2499
1695	Most event libraries are not fork-safe. The ones who are usually are	2500	Most event libraries are not fork-safe. The ones who are usually are
1696	because they rely on inefficient but fork-safe C<select> or C<poll>	2501	because they rely on inefficient but fork-safe C<select> or C<poll>
1697	calls. Only L<EV> is fully fork-aware.	2502	calls. Only L<EV> is fully fork-aware.
1698		2503
1699	If you have to fork, you must either do so I<before> creating your first	2504	If you have to fork, you must either do so I<before> creating your first
1700	watcher OR you must not use AnyEvent at all in the child.	2505	watcher OR you must not use AnyEvent at all in the child OR you must do
		2506	something completely out of the scope of AnyEvent.
1701		2507
1702		2508
1703	=head1 SECURITY CONSIDERATIONS	2509	=head1 SECURITY CONSIDERATIONS
1704		2510
1705	AnyEvent can be forced to load any event model via	2511	AnyEvent can be forced to load any event model via
…		…
1717	use AnyEvent;	2523	use AnyEvent;
1718		2524
1719	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2525	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1720	be used to probe what backend is used and gain other information (which is	2526	be used to probe what backend is used and gain other information (which is
1721	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2527	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1722	$ENV{PERL_ANYEGENT_STRICT}.	2528	$ENV{PERL_ANYEVENT_STRICT}.
		2529
		2530	Note that AnyEvent will remove I<all> environment variables starting with
		2531	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2532	enabled.
1723		2533
1724		2534
1725	=head1 BUGS	2535	=head1 BUGS
1726		2536
1727	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2537	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1728	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2538	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1729	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2539	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1730	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2540	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1731	pronounced).	2541	pronounced).
1732		2542
1733		2543
1734	=head1 SEE ALSO	2544	=head1 SEE ALSO
1735		2545
…		…
1739	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2549	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1740		2550
1741	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2551	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1742	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2552	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1743	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2553	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1744	L<AnyEvent::Impl::POE>.	2554	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1745		2555
1746	Non-blocking file handles, sockets, TCP clients and	2556	Non-blocking file handles, sockets, TCP clients and
1747	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2557	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1748		2558
1749	Asynchronous DNS: L<AnyEvent::DNS>.	2559	Asynchronous DNS: L<AnyEvent::DNS>.
1750		2560
1751	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2561	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2562	L<Coro::Event>,
1752		2563
1753	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2564	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2565	L<AnyEvent::HTTP>.
1754		2566
1755		2567
1756	=head1 AUTHOR	2568	=head1 AUTHOR
1757		2569
1758	Marc Lehmann <schmorp@schmorp.de>	2570	Marc Lehmann <schmorp@schmorp.de>

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