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Revision 1.269 by root, Fri Jul 31 20:16:29 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 try Event, and, failing
		812	that, will fall back to its own pure-perl implementation, which is
		813	available everywhere as it comes with AnyEvent itself.
		814
		815	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		816	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		817	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		818
		819	=item Backends that are transparently being picked up when they are used.
		820
		821	These will be used when they are currently loaded when the first watcher
		822	is created, in which case it is assumed that the application is using
		823	them. This means that AnyEvent will automatically pick the right backend
		824	when the main program loads an event module before anything starts to
		825	create watchers. Nothing special needs to be done by the main program.
		826
		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 = 4.9;
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::],	1156	[Event:: => AnyEvent::Impl::Event::, 1],
860	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1157	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
861	# everything below here will not be autoprobed	1158	# everything below here will not (normally) be autoprobed
862	# as the pureperl backend should work everywhere	1159	# as the pureperl backend should work everywhere
863	# and is usually faster	1160	# and is usually faster
		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	# [0, IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1174	# [0, IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1175	# [0, IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
871	);	1176	);
872		1177
873	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1178	our %method = map +($_ => 1),
		1179	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
874		1180
875	our @post_detect;	1181	our @post_detect;
876		1182
877	sub post_detect(&) {	1183	sub post_detect(&) {
878	my ($cb) = @_;	1184	my ($cb) = @_;
879		1185
880	if ($MODEL) {	1186	if ($MODEL) {
881	$cb->();	1187	$cb->();
882		1188
883	1	1189	undef
884	} else {	1190	} else {
885	push @post_detect, $cb;	1191	push @post_detect, $cb;
886		1192
887	defined wantarray	1193	defined wantarray
888	? bless \$cb, "AnyEvent::Util::PostDetect"	1194	? bless \$cb, "AnyEvent::Util::postdetect"
889	: ()	1195	: ()
890	}	1196	}
891	}	1197	}
892		1198
893	sub AnyEvent::Util::PostDetect::DESTROY {	1199	sub AnyEvent::Util::postdetect::DESTROY {
894	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1200	@post_detect = grep $_ != ${$_[0]}, @post_detect;
895	}	1201	}
896		1202
897	sub detect() {	1203	sub detect() {
898	unless ($MODEL) {	1204	unless ($MODEL) {
899	no strict 'refs';
900	local $SIG{__DIE__};	1205	local $SIG{__DIE__};
901		1206
902	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1207	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
903	my $model = "AnyEvent::Impl::$1";	1208	my $model = "AnyEvent::Impl::$1";
904	if (eval "require $model") {	1209	if (eval "require $model") {
905	$MODEL = $model;	1210	$MODEL = $model;
906	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1211	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
907	} else {	1212	} else {
908	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1213	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
909	}	1214	}
910	}	1215	}
911		1216
912	# check for already loaded models	1217	# check for already loaded models
913	unless ($MODEL) {	1218	unless ($MODEL) {
914	for (@REGISTRY, @models) {	1219	for (@REGISTRY, @models) {
915	my ($package, $model) = @$_;	1220	my ($package, $model) = @$_;
916	if (${"$package\::VERSION"} > 0) {	1221	if (${"$package\::VERSION"} > 0) {
917	if (eval "require $model") {	1222	if (eval "require $model") {
918	$MODEL = $model;	1223	$MODEL = $model;
919	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1224	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
920	last;	1225	last;
921	}	1226	}
922	}	1227	}
923	}	1228	}
924		1229
925	unless ($MODEL) {	1230	unless ($MODEL) {
926	# try to load a model	1231	# try to autoload a model
927
928	for (@REGISTRY, @models) {	1232	for (@REGISTRY, @models) {
929	my ($package, $model) = @$_;	1233	my ($package, $model, $autoload) = @$_;
		1234	if (
		1235	$autoload
930	if (eval "require $package"	1236	and eval "require $package"
931	and ${"$package\::VERSION"} > 0	1237	and ${"$package\::VERSION"} > 0
932	and eval "require $model") {	1238	and eval "require $model"
		1239	) {
933	$MODEL = $model;	1240	$MODEL = $model;
934	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1241	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
935	last;	1242	last;
936	}	1243	}
937	}	1244	}
938		1245
939	$MODEL	1246	$MODEL
940	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1247	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
941	}	1248	}
942	}	1249	}
943		1250
944	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1251	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
945		1252
…		…
955		1262
956	sub AUTOLOAD {	1263	sub AUTOLOAD {
957	(my $func = $AUTOLOAD) =~ s/.*://;	1264	(my $func = $AUTOLOAD) =~ s/.*://;
958		1265
959	$method{$func}	1266	$method{$func}
960	or croak "$func: not a valid method for AnyEvent objects";	1267	or Carp::croak "$func: not a valid method for AnyEvent objects";
961		1268
962	detect unless $MODEL;	1269	detect unless $MODEL;
963		1270
964	my $class = shift;	1271	my $class = shift;
965	$class->$func (@_);	1272	$class->$func (@_);
966	}	1273	}
967		1274
968	# utility function to dup a filehandle. this is used by many backends	1275	# utility function to dup a filehandle. this is used by many backends
969	# to support binding more than one watcher per filehandle (they usually	1276	# 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).	1277	# allow only one watcher per fd, so we dup it to get a different one).
971	sub _dupfh($$$$) {	1278	sub _dupfh($$;$$) {
972	my ($poll, $fh, $r, $w) = @_;	1279	my ($poll, $fh, $r, $w) = @_;
973		1280
974	require Fcntl;
975
976	# cygwin requires the fh mode to be matching, unix doesn't	1281	# cygwin requires the fh mode to be matching, unix doesn't
977	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1282	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		1283
981	open my $fh2, "$mode&" . fileno $fh	1284	open my $fh2, $mode, $fh
982	or die "cannot dup() filehandle: $!";	1285	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
983		1286
984	# we assume CLOEXEC is already set by perl in all important cases	1287	# we assume CLOEXEC is already set by perl in all important cases
985		1288
986	($fh2, $rw)	1289	($fh2, $rw)
987	}	1290	}
988		1291
989	package AnyEvent::Base;	1292	package AnyEvent::Base;
990		1293
991	# default implementation for now and time	1294	# default implementations for many methods
992		1295
993	use Time::HiRes ();	1296	sub _time {
		1297	# probe for availability of Time::HiRes
		1298	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1299	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1300	*_time = \&Time::HiRes::time;
		1301	# if (eval "use POSIX (); (POSIX::times())...
		1302	} else {
		1303	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1304	*_time = sub { time }; # epic fail
		1305	}
994		1306
995	sub time { Time::HiRes::time }	1307	&_time
996	sub now { Time::HiRes::time }	1308	}
		1309
		1310	sub time { _time }
		1311	sub now { _time }
		1312	sub now_update { }
997		1313
998	# default implementation for ->condvar	1314	# default implementation for ->condvar
999		1315
1000	sub condvar {	1316	sub condvar {
1001	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1317	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1002	}	1318	}
1003		1319
1004	# default implementation for ->signal	1320	# default implementation for ->signal
1005		1321
1006	our %SIG_CB;	1322	our $HAVE_ASYNC_INTERRUPT;
		1323
		1324	sub _have_async_interrupt() {
		1325	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1326	&& eval "use Async::Interrupt 1.0 (); 1")
		1327	unless defined $HAVE_ASYNC_INTERRUPT;
		1328
		1329	$HAVE_ASYNC_INTERRUPT
		1330	}
		1331
		1332	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1333	our (%SIG_ASY, %SIG_ASY_W);
		1334	our ($SIG_COUNT, $SIG_TW);
		1335
		1336	sub _signal_exec {
		1337	$HAVE_ASYNC_INTERRUPT
		1338	? $SIGPIPE_R->drain
		1339	: sysread $SIGPIPE_R, my $dummy, 9;
		1340
		1341	while (%SIG_EV) {
		1342	for (keys %SIG_EV) {
		1343	delete $SIG_EV{$_};
		1344	$_->() for values %{ $SIG_CB{$_} || {} };
		1345	}
		1346	}
		1347	}
		1348
		1349	# install a dummy wakeup watcher to reduce signal catching latency
		1350	sub _sig_add() {
		1351	unless ($SIG_COUNT++) {
		1352	# try to align timer on a full-second boundary, if possible
		1353	my $NOW = AnyEvent->now;
		1354
		1355	$SIG_TW = AnyEvent->timer (
		1356	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1357	interval => $MAX_SIGNAL_LATENCY,
		1358	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1359	);
		1360	}
		1361	}
		1362
		1363	sub _sig_del {
		1364	undef $SIG_TW
		1365	unless --$SIG_COUNT;
		1366	}
		1367
		1368	our $_sig_name_init; $_sig_name_init = sub {
		1369	eval q{ # poor man's autoloading
		1370	undef $_sig_name_init;
		1371
		1372	if (_have_async_interrupt) {
		1373	*sig2num = \&Async::Interrupt::sig2num;
		1374	*sig2name = \&Async::Interrupt::sig2name;
		1375	} else {
		1376	require Config;
		1377
		1378	my %signame2num;
		1379	@signame2num{ split ' ', $Config::Config{sig_name} }
		1380	= split ' ', $Config::Config{sig_num};
		1381
		1382	my @signum2name;
		1383	@signum2name[values %signame2num] = keys %signame2num;
		1384
		1385	*sig2num = sub($) {
		1386	$_[0] > 0 ? shift : $signame2num{+shift}
		1387	};
		1388	*sig2name = sub ($) {
		1389	$_[0] > 0 ? $signum2name[+shift] : shift
		1390	};
		1391	}
		1392	};
		1393	die if $@;
		1394	};
		1395
		1396	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1397	sub sig2name($) { &$_sig_name_init; &sig2name }
1007		1398
1008	sub signal {	1399	sub signal {
		1400	eval q{ # poor man's autoloading {}
		1401	# probe for availability of Async::Interrupt
		1402	if (_have_async_interrupt) {
		1403	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1404
		1405	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1406	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1407
		1408	} else {
		1409	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1410
		1411	require Fcntl;
		1412
		1413	if (AnyEvent::WIN32) {
		1414	require AnyEvent::Util;
		1415
		1416	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1417	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1418	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1419	} else {
		1420	pipe $SIGPIPE_R, $SIGPIPE_W;
		1421	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1422	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1423
		1424	# not strictly required, as $^F is normally 2, but let's make sure...
		1425	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1426	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1427	}
		1428
		1429	$SIGPIPE_R
		1430	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1431
		1432	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1433	}
		1434
		1435	*signal = sub {
1009	my (undef, %arg) = @_;	1436	my (undef, %arg) = @_;
1010		1437
1011	my $signal = uc $arg{signal}	1438	my $signal = uc $arg{signal}
1012	or Carp::croak "required option 'signal' is missing";	1439	or Carp::croak "required option 'signal' is missing";
1013		1440
		1441	if ($HAVE_ASYNC_INTERRUPT) {
		1442	# async::interrupt
		1443
		1444	$signal = sig2num $signal;
1014	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1445	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1446
		1447	$SIG_ASY{$signal} ||= new Async::Interrupt
		1448	cb => sub { undef $SIG_EV{$signal} },
		1449	signal => $signal,
		1450	pipe => [$SIGPIPE_R->filenos],
		1451	pipe_autodrain => 0,
		1452	;
		1453
		1454	} else {
		1455	# pure perl
		1456
		1457	# AE::Util has been loaded in signal
		1458	$signal = sig2name $signal;
		1459	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1460
1015	$SIG{$signal} ||= sub {	1461	$SIG{$signal} ||= sub {
1016	$_->() for values %{ $SIG_CB{$signal} || {} };	1462	local $!;
		1463	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1464	undef $SIG_EV{$signal};
		1465	};
		1466
		1467	# can't do signal processing without introducing races in pure perl,
		1468	# so limit the signal latency.
		1469	_sig_add;
		1470	}
		1471
		1472	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1473	};
		1474
		1475	*AnyEvent::Base::signal::DESTROY = sub {
		1476	my ($signal, $cb) = @{$_[0]};
		1477
		1478	_sig_del;
		1479
		1480	delete $SIG_CB{$signal}{$cb};
		1481
		1482	$HAVE_ASYNC_INTERRUPT
		1483	? delete $SIG_ASY{$signal}
		1484	: # delete doesn't work with older perls - they then
		1485	# print weird messages, or just unconditionally exit
		1486	# instead of getting the default action.
		1487	undef $SIG{$signal}
		1488	unless keys %{ $SIG_CB{$signal} };
		1489	};
1017	};	1490	};
1018		1491	die if $@;
1019	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1492	&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	}	1493	}
1029		1494
1030	# default implementation for ->child	1495	# default implementation for ->child
1031		1496
1032	our %PID_CB;	1497	our %PID_CB;
1033	our $CHLD_W;	1498	our $CHLD_W;
1034	our $CHLD_DELAY_W;	1499	our $CHLD_DELAY_W;
1035	our $PID_IDLE;
1036	our $WNOHANG;	1500	our $WNOHANG;
1037		1501
1038	sub _child_wait {	1502	sub _emit_childstatus($$) {
1039	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1503	my (undef, $rpid, $rstatus) = @_;
		1504
		1505	$_->($rpid, $rstatus)
1040	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1506	for values %{ $PID_CB{$rpid} || {} },
1041	(values %{ $PID_CB{0} || {} });	1507	values %{ $PID_CB{0} || {} };
1042	}
1043
1044	undef $PID_IDLE;
1045	}	1508	}
1046		1509
1047	sub _sigchld {	1510	sub _sigchld {
1048	# make sure we deliver these changes "synchronous" with the event loop.	1511	my $pid;
1049	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1512
1050	undef $CHLD_DELAY_W;	1513	AnyEvent->_emit_childstatus ($pid, $?)
1051	&_child_wait;	1514	while ($pid = waitpid -1, $WNOHANG) > 0;
1052	});
1053	}	1515	}
1054		1516
1055	sub child {	1517	sub child {
1056	my (undef, %arg) = @_;	1518	my (undef, %arg) = @_;
1057		1519
1058	defined (my $pid = $arg{pid} + 0)	1520	defined (my $pid = $arg{pid} + 0)
1059	or Carp::croak "required option 'pid' is missing";	1521	or Carp::croak "required option 'pid' is missing";
1060		1522
1061	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1523	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1062		1524
1063	unless ($WNOHANG) {	1525	# WNOHANG is almost cetrainly 1 everywhere
		1526	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1527	? 1
1064	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1528	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1065	}
1066		1529
1067	unless ($CHLD_W) {	1530	unless ($CHLD_W) {
1068	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1531	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1069	# child could be a zombie already, so make at least one round	1532	# child could be a zombie already, so make at least one round
1070	&_sigchld;	1533	&_sigchld;
1071	}	1534	}
1072		1535
1073	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1536	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1074	}	1537	}
1075		1538
1076	sub AnyEvent::Base::Child::DESTROY {	1539	sub AnyEvent::Base::child::DESTROY {
1077	my ($pid, $cb) = @{$_[0]};	1540	my ($pid, $cb) = @{$_[0]};
1078		1541
1079	delete $PID_CB{$pid}{$cb};	1542	delete $PID_CB{$pid}{$cb};
1080	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1543	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1081		1544
1082	undef $CHLD_W unless keys %PID_CB;	1545	undef $CHLD_W unless keys %PID_CB;
1083	}	1546	}
1084		1547
		1548	# idle emulation is done by simply using a timer, regardless
		1549	# of whether the process is idle or not, and not letting
		1550	# the callback use more than 50% of the time.
		1551	sub idle {
		1552	my (undef, %arg) = @_;
		1553
		1554	my ($cb, $w, $rcb) = $arg{cb};
		1555
		1556	$rcb = sub {
		1557	if ($cb) {
		1558	$w = _time;
		1559	&$cb;
		1560	$w = _time - $w;
		1561
		1562	# never use more then 50% of the time for the idle watcher,
		1563	# within some limits
		1564	$w = 0.0001 if $w < 0.0001;
		1565	$w = 5 if $w > 5;
		1566
		1567	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1568	} else {
		1569	# clean up...
		1570	undef $w;
		1571	undef $rcb;
		1572	}
		1573	};
		1574
		1575	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1576
		1577	bless \\$cb, "AnyEvent::Base::idle"
		1578	}
		1579
		1580	sub AnyEvent::Base::idle::DESTROY {
		1581	undef $${$_[0]};
		1582	}
		1583
1085	package AnyEvent::CondVar;	1584	package AnyEvent::CondVar;
1086		1585
1087	our @ISA = AnyEvent::CondVar::Base::;	1586	our @ISA = AnyEvent::CondVar::Base::;
1088		1587
1089	package AnyEvent::CondVar::Base;	1588	package AnyEvent::CondVar::Base;
1090		1589
1091	use overload	1590	#use overload
1092	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1591	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1093	fallback => 1;	1592	# fallback => 1;
		1593
		1594	# save 300+ kilobytes by dirtily hardcoding overloading
		1595	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1596	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1597	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1598	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1599
		1600	our $WAITING;
1094		1601
1095	sub _send {	1602	sub _send {
1096	# nop	1603	# nop
1097	}	1604	}
1098		1605
…		…
1111	sub ready {	1618	sub ready {
1112	$_[0]{_ae_sent}	1619	$_[0]{_ae_sent}
1113	}	1620	}
1114		1621
1115	sub _wait {	1622	sub _wait {
		1623	$WAITING
		1624	and !$_[0]{_ae_sent}
		1625	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1626
		1627	local $WAITING = 1;
1116	AnyEvent->one_event while !$_[0]{_ae_sent};	1628	AnyEvent->one_event while !$_[0]{_ae_sent};
1117	}	1629	}
1118		1630
1119	sub recv {	1631	sub recv {
1120	$_[0]->_wait;	1632	$_[0]->_wait;
…		…
1122	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1634	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1123	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1635	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1124	}	1636	}
1125		1637
1126	sub cb {	1638	sub cb {
1127	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1639	my $cv = shift;
		1640
		1641	@_
		1642	and $cv->{_ae_cb} = shift
		1643	and $cv->{_ae_sent}
		1644	and (delete $cv->{_ae_cb})->($cv);
1128	$_[0]{_ae_cb}	1645	$cv->{_ae_cb}
1129	}	1646	}
1130		1647
1131	sub begin {	1648	sub begin {
1132	++$_[0]{_ae_counter};	1649	++$_[0]{_ae_counter};
1133	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1650	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1139	}	1656	}
1140		1657
1141	# undocumented/compatibility with pre-3.4	1658	# undocumented/compatibility with pre-3.4
1142	*broadcast = \&send;	1659	*broadcast = \&send;
1143	*wait = \&_wait;	1660	*wait = \&_wait;
		1661
		1662	#############################################################################
		1663	# "new" API, currently only emulation of it
		1664	#############################################################################
		1665
		1666	package AE;
		1667
		1668	sub io($$$) {
		1669	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1670	}
		1671
		1672	sub timer($$$) {
		1673	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2]);
		1674	}
		1675
		1676	sub signal($$) {
		1677	AnyEvent->signal (signal => $_[0], cb => $_[1]);
		1678	}
		1679
		1680	sub child($$) {
		1681	AnyEvent->child (pid => $_[0], cb => $_[1]);
		1682	}
		1683
		1684	sub idle($) {
		1685	AnyEvent->idle (cb => $_[0]);
		1686	}
		1687
		1688	sub cv() {
		1689	AnyEvent->condvar
		1690	}
		1691
		1692	sub now() {
		1693	AnyEvent->now
		1694	}
		1695
		1696	sub now_update() {
		1697	AnyEvent->now_update
		1698	}
		1699
		1700	sub time() {
		1701	AnyEvent->time
		1702	}
		1703
		1704	=head1 ERROR AND EXCEPTION HANDLING
		1705
		1706	In general, AnyEvent does not do any error handling - it relies on the
		1707	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1708	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1709	checking of all AnyEvent methods, however, which is highly useful during
		1710	development.
		1711
		1712	As for exception handling (i.e. runtime errors and exceptions thrown while
		1713	executing a callback), this is not only highly event-loop specific, but
		1714	also not in any way wrapped by this module, as this is the job of the main
		1715	program.
		1716
		1717	The pure perl event loop simply re-throws the exception (usually
		1718	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1719	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1720	so on.
		1721
		1722	=head1 ENVIRONMENT VARIABLES
		1723
		1724	The following environment variables are used by this module or its
		1725	submodules.
		1726
		1727	Note that AnyEvent will remove I<all> environment variables starting with
		1728	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1729	enabled.
		1730
		1731	=over 4
		1732
		1733	=item C<PERL_ANYEVENT_VERBOSE>
		1734
		1735	By default, AnyEvent will be completely silent except in fatal
		1736	conditions. You can set this environment variable to make AnyEvent more
		1737	talkative.
		1738
		1739	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1740	conditions, such as not being able to load the event model specified by
		1741	C<PERL_ANYEVENT_MODEL>.
		1742
		1743	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1744	model it chooses.
		1745
		1746	When set to C<8> or higher, then AnyEvent will report extra information on
		1747	which optional modules it loads and how it implements certain features.
		1748
		1749	=item C<PERL_ANYEVENT_STRICT>
		1750
		1751	AnyEvent does not do much argument checking by default, as thorough
		1752	argument checking is very costly. Setting this variable to a true value
		1753	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1754	check the arguments passed to most method calls. If it finds any problems,
		1755	it will croak.
		1756
		1757	In other words, enables "strict" mode.
		1758
		1759	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1760	>>, it is definitely recommended to keep it off in production. Keeping
		1761	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1762	can be very useful, however.
		1763
		1764	=item C<PERL_ANYEVENT_MODEL>
		1765
		1766	This can be used to specify the event model to be used by AnyEvent, before
		1767	auto detection and -probing kicks in. It must be a string consisting
		1768	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1769	and the resulting module name is loaded and if the load was successful,
		1770	used as event model. If it fails to load AnyEvent will proceed with
		1771	auto detection and -probing.
		1772
		1773	This functionality might change in future versions.
		1774
		1775	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1776	could start your program like this:
		1777
		1778	PERL_ANYEVENT_MODEL=Perl perl ...
		1779
		1780	=item C<PERL_ANYEVENT_PROTOCOLS>
		1781
		1782	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1783	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1784	of auto probing).
		1785
		1786	Must be set to a comma-separated list of protocols or address families,
		1787	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1788	used, and preference will be given to protocols mentioned earlier in the
		1789	list.
		1790
		1791	This variable can effectively be used for denial-of-service attacks
		1792	against local programs (e.g. when setuid), although the impact is likely
		1793	small, as the program has to handle conenction and other failures anyways.
		1794
		1795	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1796	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1797	- only support IPv4, never try to resolve or contact IPv6
		1798	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1799	IPv6, but prefer IPv6 over IPv4.
		1800
		1801	=item C<PERL_ANYEVENT_EDNS0>
		1802
		1803	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1804	for DNS. This extension is generally useful to reduce DNS traffic, but
		1805	some (broken) firewalls drop such DNS packets, which is why it is off by
		1806	default.
		1807
		1808	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1809	EDNS0 in its DNS requests.
		1810
		1811	=item C<PERL_ANYEVENT_MAX_FORKS>
		1812
		1813	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1814	will create in parallel.
		1815
		1816	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1817
		1818	The default value for the C<max_outstanding> parameter for the default DNS
		1819	resolver - this is the maximum number of parallel DNS requests that are
		1820	sent to the DNS server.
		1821
		1822	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1823
		1824	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1825	configuration) in the default resolver. When set to the empty string, no
		1826	default config will be used.
		1827
		1828	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1829
		1830	When neither C<ca_file> nor C<ca_path> was specified during
		1831	L<AnyEvent::TLS> context creation, and either of these environment
		1832	variables exist, they will be used to specify CA certificate locations
		1833	instead of a system-dependent default.
		1834
		1835	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1836
		1837	When these are set to C<1>, then the respective modules are not
		1838	loaded. Mostly good for testing AnyEvent itself.
		1839
		1840	=back
1144		1841
1145	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1842	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1146		1843
1147	This is an advanced topic that you do not normally need to use AnyEvent in	1844	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	1845	a module. This section is only of use to event loop authors who want to
…		…
1182		1879
1183	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1880	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1184	condition variables: code blocking while waiting for a condition will	1881	condition variables: code blocking while waiting for a condition will
1185	C<die>. This still works with most modules/usages, and blocking calls must	1882	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.	1883	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 load C<AnyEvent::Strict> and then to thoroughly
1212	check the arguments passed to most method calls. If it finds any problems
1213	it will croak.
1214
1215	In other words, enables "strict" mode.
1216
1217	Unlike C<use strict> it is definitely recommended ot keep it off in
1218	production.
1219
1220	=item C<PERL_ANYEVENT_MODEL>
1221
1222	This can be used to specify the event model to be used by AnyEvent, before
1223	auto detection and -probing kicks in. It must be a string consisting
1224	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1225	and the resulting module name is loaded and if the load was successful,
1226	used as event model. If it fails to load AnyEvent will proceed with
1227	auto detection and -probing.
1228
1229	This functionality might change in future versions.
1230
1231	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1232	could start your program like this:
1233
1234	PERL_ANYEVENT_MODEL=Perl perl ...
1235
1236	=item C<PERL_ANYEVENT_PROTOCOLS>
1237
1238	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1239	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1240	of auto probing).
1241
1242	Must be set to a comma-separated list of protocols or address families,
1243	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1244	used, and preference will be given to protocols mentioned earlier in the
1245	list.
1246
1247	This variable can effectively be used for denial-of-service attacks
1248	against local programs (e.g. when setuid), although the impact is likely
1249	small, as the program has to handle connection errors already-
1250
1251	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1252	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1253	- only support IPv4, never try to resolve or contact IPv6
1254	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1255	IPv6, but prefer IPv6 over IPv4.
1256
1257	=item C<PERL_ANYEVENT_EDNS0>
1258
1259	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1260	for DNS. This extension is generally useful to reduce DNS traffic, but
1261	some (broken) firewalls drop such DNS packets, which is why it is off by
1262	default.
1263
1264	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1265	EDNS0 in its DNS requests.
1266
1267	=item C<PERL_ANYEVENT_MAX_FORKS>
1268
1269	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1270	will create in parallel.
1271
1272	=back
1273		1884
1274	=head1 EXAMPLE PROGRAM	1885	=head1 EXAMPLE PROGRAM
1275		1886
1276	The following program uses an I/O watcher to read data from STDIN, a timer	1887	The following program uses an I/O watcher to read data from STDIN, a timer
1277	to display a message once per second, and a condition variable to quit the	1888	to display a message once per second, and a condition variable to quit the
…		…
1471	watcher.	2082	watcher.
1472		2083
1473	=head3 Results	2084	=head3 Results
1474		2085
1475	name watchers bytes create invoke destroy comment	2086	name watchers bytes create invoke destroy comment
1476	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2087	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1477	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2088	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1478	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2089	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1479	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2090	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1480	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2091	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1481	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2092	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		2093	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		2094	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1482	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2095	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1483	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2096	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1484	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2097	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1485	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2098	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1486		2099
1487	=head3 Discussion	2100	=head3 Discussion
1488		2101
1489	The benchmark does I<not> measure scalability of the event loop very	2102	The benchmark does I<not> measure scalability of the event loop very
1490	well. For example, a select-based event loop (such as the pure perl one)	2103	well. For example, a select-based event loop (such as the pure perl one)
…		…
1515	performance becomes really bad with lots of file descriptors (and few of	2128	performance becomes really bad with lots of file descriptors (and few of
1516	them active), of course, but this was not subject of this benchmark.	2129	them active), of course, but this was not subject of this benchmark.
1517		2130
1518	The C<Event> module has a relatively high setup and callback invocation	2131	The C<Event> module has a relatively high setup and callback invocation
1519	cost, but overall scores in on the third place.	2132	cost, but overall scores in on the third place.
		2133
		2134	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2135	when using its pure perl backend.
1520		2136
1521	C<Glib>'s memory usage is quite a bit higher, but it features a	2137	C<Glib>'s memory usage is quite a bit higher, but it features a
1522	faster callback invocation and overall ends up in the same class as	2138	faster callback invocation and overall ends up in the same class as
1523	C<Event>. However, Glib scales extremely badly, doubling the number of	2139	C<Event>. However, Glib scales extremely badly, doubling the number of
1524	watchers increases the processing time by more than a factor of four,	2140	watchers increases the processing time by more than a factor of four,
…		…
1602	it to another server. This includes deleting the old timeout and creating	2218	it to another server. This includes deleting the old timeout and creating
1603	a new one that moves the timeout into the future.	2219	a new one that moves the timeout into the future.
1604		2220
1605	=head3 Results	2221	=head3 Results
1606		2222
1607	name sockets create request	2223	name sockets create request
1608	EV 20000 69.01 11.16	2224	EV 20000 69.01 11.16
1609	Perl 20000 73.32 35.87	2225	Perl 20000 73.32 35.87
		2226	IOAsync 20000 157.00 98.14 epoll
		2227	IOAsync 20000 159.31 616.06 poll
1610	Event 20000 212.62 257.32	2228	Event 20000 212.62 257.32
1611	Glib 20000 651.16 1896.30	2229	Glib 20000 651.16 1896.30
1612	POE 20000 349.67 12317.24 uses POE::Loop::Event	2230	POE 20000 349.67 12317.24 uses POE::Loop::Event
1613		2231
1614	=head3 Discussion	2232	=head3 Discussion
1615		2233
1616	This benchmark I<does> measure scalability and overall performance of the	2234	This benchmark I<does> measure scalability and overall performance of the
1617	particular event loop.	2235	particular event loop.
…		…
1619	EV is again fastest. Since it is using epoll on my system, the setup time	2237	EV is again fastest. Since it is using epoll on my system, the setup time
1620	is relatively high, though.	2238	is relatively high, though.
1621		2239
1622	Perl surprisingly comes second. It is much faster than the C-based event	2240	Perl surprisingly comes second. It is much faster than the C-based event
1623	loops Event and Glib.	2241	loops Event and Glib.
		2242
		2243	IO::Async performs very well when using its epoll backend, and still quite
		2244	good compared to Glib when using its pure perl backend.
1624		2245
1625	Event suffers from high setup time as well (look at its code and you will	2246	Event suffers from high setup time as well (look at its code and you will
1626	understand why). Callback invocation also has a high overhead compared to	2247	understand why). Callback invocation also has a high overhead compared to
1627	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2248	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1628	uses select or poll in basically all documented configurations.	2249	uses select or poll in basically all documented configurations.
…		…
1691	=item * C-based event loops perform very well with small number of	2312	=item * C-based event loops perform very well with small number of
1692	watchers, as the management overhead dominates.	2313	watchers, as the management overhead dominates.
1693		2314
1694	=back	2315	=back
1695		2316
		2317	=head2 THE IO::Lambda BENCHMARK
		2318
		2319	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2320	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2321	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2322	shouldn't come as a surprise to anybody). As such, the benchmark is
		2323	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2324	very optimal. But how would AnyEvent compare when used without the extra
		2325	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2326
		2327	The benchmark itself creates an echo-server, and then, for 500 times,
		2328	connects to the echo server, sends a line, waits for the reply, and then
		2329	creates the next connection. This is a rather bad benchmark, as it doesn't
		2330	test the efficiency of the framework or much non-blocking I/O, but it is a
		2331	benchmark nevertheless.
		2332
		2333	name runtime
		2334	Lambda/select 0.330 sec
		2335	+ optimized 0.122 sec
		2336	Lambda/AnyEvent 0.327 sec
		2337	+ optimized 0.138 sec
		2338	Raw sockets/select 0.077 sec
		2339	POE/select, components 0.662 sec
		2340	POE/select, raw sockets 0.226 sec
		2341	POE/select, optimized 0.404 sec
		2342
		2343	AnyEvent/select/nb 0.085 sec
		2344	AnyEvent/EV/nb 0.068 sec
		2345	+state machine 0.134 sec
		2346
		2347	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2348	benchmarks actually make blocking connects and use 100% blocking I/O,
		2349	defeating the purpose of an event-based solution. All of the newly
		2350	written AnyEvent benchmarks use 100% non-blocking connects (using
		2351	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2352	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2353	generally require a lot more bookkeeping and event handling than blocking
		2354	connects (which involve a single syscall only).
		2355
		2356	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2357	offers similar expressive power as POE and IO::Lambda, using conventional
		2358	Perl syntax. This means that both the echo server and the client are 100%
		2359	non-blocking, further placing it at a disadvantage.
		2360
		2361	As you can see, the AnyEvent + EV combination even beats the
		2362	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2363	backend easily beats IO::Lambda and POE.
		2364
		2365	And even the 100% non-blocking version written using the high-level (and
		2366	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2367	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2368	in a non-blocking way.
		2369
		2370	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2371	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2372	part of the IO::lambda distribution and were used without any changes.
		2373
		2374
		2375	=head1 SIGNALS
		2376
		2377	AnyEvent currently installs handlers for these signals:
		2378
		2379	=over 4
		2380
		2381	=item SIGCHLD
		2382
		2383	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2384	emulation for event loops that do not support them natively. Also, some
		2385	event loops install a similar handler.
		2386
		2387	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2388	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2389
		2390	=item SIGPIPE
		2391
		2392	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2393	when AnyEvent gets loaded.
		2394
		2395	The rationale for this is that AnyEvent users usually do not really depend
		2396	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2397	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2398	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2399	some random socket.
		2400
		2401	The rationale for installing a no-op handler as opposed to ignoring it is
		2402	that this way, the handler will be restored to defaults on exec.
		2403
		2404	Feel free to install your own handler, or reset it to defaults.
		2405
		2406	=back
		2407
		2408	=cut
		2409
		2410	undef $SIG{CHLD}
		2411	if $SIG{CHLD} eq 'IGNORE';
		2412
		2413	$SIG{PIPE} = sub { }
		2414	unless defined $SIG{PIPE};
		2415
		2416	=head1 RECOMMENDED/OPTIONAL MODULES
		2417
		2418	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2419	it's built-in modules) are required to use it.
		2420
		2421	That does not mean that AnyEvent won't take advantage of some additional
		2422	modules if they are installed.
		2423
		2424	This section epxlains which additional modules will be used, and how they
		2425	affect AnyEvent's operetion.
		2426
		2427	=over 4
		2428
		2429	=item L<Async::Interrupt>
		2430
		2431	This slightly arcane module is used to implement fast signal handling: To
		2432	my knowledge, there is no way to do completely race-free and quick
		2433	signal handling in pure perl. To ensure that signals still get
		2434	delivered, AnyEvent will start an interval timer to wake up perl (and
		2435	catch the signals) with some delay (default is 10 seconds, look for
		2436	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2437
		2438	If this module is available, then it will be used to implement signal
		2439	catching, which means that signals will not be delayed, and the event loop
		2440	will not be interrupted regularly, which is more efficient (And good for
		2441	battery life on laptops).
		2442
		2443	This affects not just the pure-perl event loop, but also other event loops
		2444	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2445
		2446	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2447	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2448	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2449	does nothing for those backends.
		2450
		2451	=item L<EV>
		2452
		2453	This module isn't really "optional", as it is simply one of the backend
		2454	event loops that AnyEvent can use. However, it is simply the best event
		2455	loop available in terms of features, speed and stability: It supports
		2456	the AnyEvent API optimally, implements all the watcher types in XS, does
		2457	automatic timer adjustments even when no monotonic clock is available,
		2458	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2459	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2460	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2461
		2462	=item L<Guard>
		2463
		2464	The guard module, when used, will be used to implement
		2465	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2466	lot less memory), but otherwise doesn't affect guard operation much. It is
		2467	purely used for performance.
		2468
		2469	=item L<JSON> and L<JSON::XS>
		2470
		2471	This module is required when you want to read or write JSON data via
		2472	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2473	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2474
		2475	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2476	installed.
		2477
		2478	=item L<Net::SSLeay>
		2479
		2480	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2481	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2482	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2483
		2484	=item L<Time::HiRes>
		2485
		2486	This module is part of perl since release 5.008. It will be used when the
		2487	chosen event library does not come with a timing source on it's own. The
		2488	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2489	try to use a monotonic clock for timing stability.
		2490
		2491	=back
		2492
1696		2493
1697	=head1 FORK	2494	=head1 FORK
1698		2495
1699	Most event libraries are not fork-safe. The ones who are usually are	2496	Most event libraries are not fork-safe. The ones who are usually are
1700	because they rely on inefficient but fork-safe C<select> or C<poll>	2497	because they rely on inefficient but fork-safe C<select> or C<poll>
1701	calls. Only L<EV> is fully fork-aware.	2498	calls. Only L<EV> is fully fork-aware.
1702		2499
1703	If you have to fork, you must either do so I<before> creating your first	2500	If you have to fork, you must either do so I<before> creating your first
1704	watcher OR you must not use AnyEvent at all in the child.	2501	watcher OR you must not use AnyEvent at all in the child OR you must do
		2502	something completely out of the scope of AnyEvent.
1705		2503
1706		2504
1707	=head1 SECURITY CONSIDERATIONS	2505	=head1 SECURITY CONSIDERATIONS
1708		2506
1709	AnyEvent can be forced to load any event model via	2507	AnyEvent can be forced to load any event model via
…		…
1721	use AnyEvent;	2519	use AnyEvent;
1722		2520
1723	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2521	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1724	be used to probe what backend is used and gain other information (which is	2522	be used to probe what backend is used and gain other information (which is
1725	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2523	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1726	$ENV{PERL_ANYEGENT_STRICT}.	2524	$ENV{PERL_ANYEVENT_STRICT}.
		2525
		2526	Note that AnyEvent will remove I<all> environment variables starting with
		2527	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2528	enabled.
1727		2529
1728		2530
1729	=head1 BUGS	2531	=head1 BUGS
1730		2532
1731	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2533	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1732	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2534	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1733	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2535	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1734	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2536	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1735	pronounced).	2537	pronounced).
1736		2538
1737		2539
1738	=head1 SEE ALSO	2540	=head1 SEE ALSO
1739		2541
…		…
1743	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2545	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1744		2546
1745	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2547	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1746	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2548	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1747	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2549	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1748	L<AnyEvent::Impl::POE>.	2550	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1749		2551
1750	Non-blocking file handles, sockets, TCP clients and	2552	Non-blocking file handles, sockets, TCP clients and
1751	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2553	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1752		2554
1753	Asynchronous DNS: L<AnyEvent::DNS>.	2555	Asynchronous DNS: L<AnyEvent::DNS>.
1754		2556
1755	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2557	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2558	L<Coro::Event>,
1756		2559
1757	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2560	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2561	L<AnyEvent::HTTP>.
1758		2562
1759		2563
1760	=head1 AUTHOR	2564	=head1 AUTHOR
1761		2565
1762	Marc Lehmann <schmorp@schmorp.de>	2566	Marc Lehmann <schmorp@schmorp.de>

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