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Revision 1.175 by root, Sun Jul 27 08:43:32 2008 UTC vs.
Revision 1.276 by root, Sun Aug 9 10:53:33 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 { ... });
12		14
		15	# one-shot or repeating timers
13	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });	16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
14	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...	17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
15		18
16	print AnyEvent->now; # prints current event loop time	19	print AnyEvent->now; # prints current event loop time
17	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.	20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
18		21
		22	# POSIX signal
19	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });	23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
20		24
		25	# child process exit
21	my $w = AnyEvent->child (pid => $pid, cb => sub {	26	my $w = AnyEvent->child (pid => $pid, cb => sub {
22	my ($pid, $status) = @_;	27	my ($pid, $status) = @_;
23	...	28	...
24	});	29	});
		30
		31	# called when event loop idle (if applicable)
		32	my $w = AnyEvent->idle (cb => sub { ... });
25		33
26	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
27	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
28	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
29	# use a condvar in callback mode:	37	# use a condvar in callback mode:
…		…
32	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
33		41
34	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
35	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
36	L<AnyEvent::Intro> manpage.	44	L<AnyEvent::Intro> manpage.
		45
		46	=head1 SUPPORT
		47
		48	There is a mailinglist for discussing all things AnyEvent, and an IRC
		49	channel, too.
		50
		51	See the AnyEvent project page at the B<Schmorpforge Ta-Sa Software
		52	Repository>, at L<http://anyevent.schmorp.de>, for more info.
37		53
38	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)	54	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
39		55
40	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen	56	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
41	nowadays. So what is different about AnyEvent?	57	nowadays. So what is different about AnyEvent?
…		…
137	These watchers are normal Perl objects with normal Perl lifetime. After	153	These watchers are normal Perl objects with normal Perl lifetime. After
138	creating a watcher it will immediately "watch" for events and invoke the	154	creating a watcher it will immediately "watch" for events and invoke the
139	callback when the event occurs (of course, only when the event model	155	callback when the event occurs (of course, only when the event model
140	is in control).	156	is in control).
141		157
		158	Note that B<callbacks must not permanently change global variables>
		159	potentially in use by the event loop (such as C<$_> 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
142	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
143	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
144	to it).	166	to it).
145		167
146	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.
…		…
159	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
160	declared.	182	declared.
161		183
162	=head2 I/O WATCHERS	184	=head2 I/O WATCHERS
163		185
		186	$w = AnyEvent->io (
		187	fh => <filehandle_or_fileno>,
		188	poll => <"r" or "w">,
		189	cb => <callback>,
		190	);
		191
164	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
165	with the following mandatory key-value pairs as arguments:	193	with the following mandatory key-value pairs as arguments:
166		194
167	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
168	(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
169	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
170	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
171	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.
172		206
173	Although the callback might get passed parameters, their value and	207	Although the callback might get passed parameters, their value and
174	presence is undefined and you cannot rely on them. Portable AnyEvent	208	presence is undefined and you cannot rely on them. Portable AnyEvent
175	callbacks cannot use arguments passed to I/O watcher callbacks.	209	callbacks cannot use arguments passed to I/O watcher callbacks.
176		210
…		…
191	undef $w;	225	undef $w;
192	});	226	});
193		227
194	=head2 TIME WATCHERS	228	=head2 TIME WATCHERS
195		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
196	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 >>
197	method with the following mandatory arguments:	239	method with the following mandatory arguments:
198		240
199	C<after> specifies after how many seconds (fractional values are	241	C<after> specifies after how many seconds (fractional values are
200	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
…		…
308	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
309	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
310	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	352	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
311	account.	353	account.
312		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
313	=back	370	=back
314		371
315	=head2 SIGNAL WATCHERS	372	=head2 SIGNAL WATCHERS
		373
		374	$w = AnyEvent->signal (signal => <uppercase_signal_name>, cb => <callback>);
316		375
317	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
318	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
319	callback to be invoked whenever a signal occurs.	378	callback to be invoked whenever a signal occurs.
320		379
…		…
326	invocation, and callback invocation will be synchronous. Synchronous means	385	invocation, and callback invocation will be synchronous. Synchronous means
327	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,
328	but it is guaranteed not to interrupt any other callbacks.	387	but it is guaranteed not to interrupt any other callbacks.
329		388
330	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
331	between multiple watchers.	390	between multiple watchers, and AnyEvent will ensure that signals will not
		391	interrupt your program at bad times.
332		392
333	This watcher might use C<%SIG>, so programs overwriting those signals	393	This watcher might use C<%SIG> (depending on the event loop used),
334	directly will likely not work correctly.	394	so programs overwriting those signals directly will likely not work
		395	correctly.
335		396
336	Example: exit on SIGINT	397	Example: exit on SIGINT
337		398
338	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	399	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
339		400
		401	=head3 Signal Races, Delays and Workarounds
		402
		403	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		404	callbacks to signals in a generic way, which is a pity, as you cannot
		405	do race-free signal handling in perl, requiring C libraries for
		406	this. AnyEvent will try to do it's best, which means in some cases,
		407	signals will be delayed. The maximum time a signal might be delayed is
		408	specified in C<$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
340	=head2 CHILD PROCESS WATCHERS	421	=head2 CHILD PROCESS WATCHERS
341		422
		423	$w = AnyEvent->child (pid => <process id>, cb => <callback>);
		424
342	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.
343		426
344	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,
345	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
346	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
347	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
348	and exit status (as returned by waitpid), so unlike other watcher types,	431	(stopped/continued).
349	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).
350		441
351	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
352	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
353	have exited already (and no SIGCHLD will be sent anymore).	444	have exited already (and no SIGCHLD will be sent anymore).
354		445
355	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
356	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
357	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.
358		452
359	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
360	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
361	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.
362		461
363	Example: fork a process and wait for it	462	Example: fork a process and wait for it
364		463
365	my $done = AnyEvent->condvar;	464	my $done = AnyEvent->condvar;
366		465
…		…
376	);	475	);
377		476
378	# do something else, then wait for process exit	477	# do something else, then wait for process exit
379	$done->recv;	478	$done->recv;
380		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
381	=head2 CONDITION VARIABLES	517	=head2 CONDITION VARIABLES
		518
		519	$cv = AnyEvent->condvar;
		520
		521	$cv->send (<list>);
		522	my @res = $cv->recv;
382		523
383	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
384	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
385	will actively watch for new events and call your callbacks.	526	will actively watch for new events and call your callbacks.
386		527
387	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
388	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).
389		530
390	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
391	because they represent a condition that must become true.	532	because they represent a condition that must become true.
392		533
		534	Now is probably a good time to look at the examples further below.
		535
393	Condition variables can be created by calling the C<< AnyEvent->condvar	536	Condition variables can be created by calling the C<< AnyEvent->condvar
394	>> method, usually without arguments. The only argument pair allowed is	537	>> method, usually without arguments. The only argument pair allowed is
395
396	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
397	becomes true, with the condition variable as the first argument (but not	539	becomes true, with the condition variable as the first argument (but not
398	the results).	540	the results).
399		541
400	After creation, the condition variable is "false" until it becomes "true"	542	After creation, the condition variable is "false" until it becomes "true"
…		…
405	Condition variables are similar to callbacks, except that you can	547	Condition variables are similar to callbacks, except that you can
406	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
407	in time where multiple outstanding events have been processed. And yet	549	in time where multiple outstanding events have been processed. And yet
408	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
409	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
410	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.
411		554
412	Condition variables are very useful to signal that something has finished,	555	Condition variables are very useful to signal that something has finished,
413	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,
414	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
415	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
…		…
449	after => 1,	592	after => 1,
450	cb => sub { $result_ready->send },	593	cb => sub { $result_ready->send },
451	);	594	);
452		595
453	# this "blocks" (while handling events) till the callback	596	# this "blocks" (while handling events) till the callback
454	# calls send	597	# calls -<send
455	$result_ready->recv;	598	$result_ready->recv;
456		599
457	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
458	condition variables are also code references.	601	variables are also callable directly.
459		602
460	my $done = AnyEvent->condvar;	603	my $done = AnyEvent->condvar;
461	my $delay = AnyEvent->timer (after => 5, cb => $done);	604	my $delay = AnyEvent->timer (after => 5, cb => $done);
462	$done->recv;	605	$done->recv;
463		606
…		…
469		612
470	...	613	...
471		614
472	my @info = $couchdb->info->recv;	615	my @info = $couchdb->info->recv;
473		616
474	And this is how you would just ste a callback to be called whenever the	617	And this is how you would just set a callback to be called whenever the
475	results are available:	618	results are available:
476		619
477	$couchdb->info->cb (sub {	620	$couchdb->info->cb (sub {
478	my @info = $_[0]->recv;	621	my @info = $_[0]->recv;
479	});	622	});
…		…
497	immediately from within send.	640	immediately from within send.
498		641
499	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
500	future C<< ->recv >> calls.	643	future C<< ->recv >> calls.
501		644
502	Condition variables are overloaded so one can call them directly	645	Condition variables are overloaded so one can call them directly (as if
503	(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
504	C<send>. Note, however, that many C-based event loops do not handle	647	C<send>.
505	overloading, so as tempting as it may be, passing a condition variable
506	instead of a callback does not work. Both the pure perl and EV loops
507	support overloading, however, as well as all functions that use perl to
508	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
509	example).
510		648
511	=item $cv->croak ($error)	649	=item $cv->croak ($error)
512		650
513	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
514	C<Carp::croak> with the given error message/object/scalar.	652	C<Carp::croak> with the given error message/object/scalar.
515		653
516	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
517	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.
518		660
519	=item $cv->begin ([group callback])	661	=item $cv->begin ([group callback])
520		662
521	=item $cv->end	663	=item $cv->end
522
523	These two methods are EXPERIMENTAL and MIGHT CHANGE.
524		664
525	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
526	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
527	to use a condition variable for the whole process.	667	to use a condition variable for the whole process.
528		668
…		…
530	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
531	>>, 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
532	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
533	callback was set, C<send> will be called without any arguments.	673	callback was set, C<send> will be called without any arguments.
534		674
535	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:
536		706
537	my $cv = AnyEvent->condvar;	707	my $cv = AnyEvent->condvar;
538		708
539	my %result;	709	my %result;
540	$cv->begin (sub { $cv->send (\%result) });	710	$cv->begin (sub { $cv->send (\%result) });
…		…
560	loop, which serves two important purposes: first, it sets the callback	730	loop, which serves two important purposes: first, it sets the callback
561	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
562	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
563	doesn't execute once).	733	doesn't execute once).
564		734
565	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
566	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
567	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
568	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>.
569		740
570	=back	741	=back
571		742
572	=head3 METHODS FOR CONSUMERS	743	=head3 METHODS FOR CONSUMERS
573		744
…		…
589	function will call C<croak>.	760	function will call C<croak>.
590		761
591	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,
592	in scalar context only the first one will be returned.	763	in scalar context only the first one will be returned.
593		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
594	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
595	(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
596	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
597	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
598	condition variables with some kind of request results and supporting	776	condition variables with some kind of request results and supporting
599	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,
600	while still supporting blocking waits if the caller so desires).	778	while still supporting blocking waits if the caller so desires).
601		779
602	Another reason I<never> to C<< ->recv >> in a module is that you cannot
603	sensibly have two C<< ->recv >>'s in parallel, as that would require
604	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
605	can supply.
606
607	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
608	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
609	versions and also integrates coroutines into AnyEvent, making blocking
610	C<< ->recv >> calls perfectly safe as long as they are done from another
611	coroutine (one that doesn't run the event loop).
612
613	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
614	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
615	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
616	waits otherwise.	783	waits otherwise.
617		784
…		…
623	=item $cb = $cv->cb ($cb->($cv))	790	=item $cb = $cv->cb ($cb->($cv))
624		791
625	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
626	replaces it before doing so.	793	replaces it before doing so.
627		794
628	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)
629	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
630	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>
631	is guaranteed not to block.	798	inside the callback or at any later time is guaranteed not to block.
632		799
633	=back	800	=back
634		801
		802	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		803
		804	The available backend classes are (every class has its own manpage):
		805
		806	=over 4
		807
		808	=item Backends that are autoprobed when no other event loop can be found.
		809
		810	EV is the preferred backend when no other event loop seems to be in
		811	use. If EV is not installed, then AnyEvent will fall back to its own
		812	pure-perl implementation, which is available everywhere as it comes with
		813	AnyEvent itself.
		814
		815	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		816	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		817
		818	=item Backends that are transparently being picked up when they are used.
		819
		820	These will be used when they are currently loaded when the first watcher
		821	is created, in which case it is assumed that the application is using
		822	them. This means that AnyEvent will automatically pick the right backend
		823	when the main program loads an event module before anything starts to
		824	create watchers. Nothing special needs to be done by the main program.
		825
		826	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		827	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		828	AnyEvent::Impl::Tk based on Tk, very broken.
		829	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		830	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		831	AnyEvent::Impl::Irssi used when running within irssi.
		832
		833	=item Backends with special needs.
		834
		835	Qt requires the Qt::Application to be instantiated first, but will
		836	otherwise be picked up automatically. As long as the main program
		837	instantiates the application before any AnyEvent watchers are created,
		838	everything should just work.
		839
		840	AnyEvent::Impl::Qt based on Qt.
		841
		842	Support for IO::Async can only be partial, as it is too broken and
		843	architecturally limited to even support the AnyEvent API. It also
		844	is the only event loop that needs the loop to be set explicitly, so
		845	it can only be used by a main program knowing about AnyEvent. See
		846	L<AnyEvent::Impl::Async> for the gory details.
		847
		848	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		849
		850	=item Event loops that are indirectly supported via other backends.
		851
		852	Some event loops can be supported via other modules:
		853
		854	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		855
		856	B<WxWidgets> has no support for watching file handles. However, you can
		857	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		858	polls 20 times per second, which was considered to be too horrible to even
		859	consider for AnyEvent.
		860
		861	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		862	backend, so it can be supported through POE.
		863
		864	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		865	load L<POE> when detecting them, in the hope that POE will pick them up,
		866	in which case everything will be automatic.
		867
		868	=back
		869
635	=head1 GLOBAL VARIABLES AND FUNCTIONS	870	=head1 GLOBAL VARIABLES AND FUNCTIONS
636		871
		872	These are not normally required to use AnyEvent, but can be useful to
		873	write AnyEvent extension modules.
		874
637	=over 4	875	=over 4
638		876
639	=item $AnyEvent::MODEL	877	=item $AnyEvent::MODEL
640		878
641	Contains C<undef> until the first watcher is being created. Then it	879	Contains C<undef> until the first watcher is being created, before the
		880	backend has been autodetected.
		881
642	contains the event model that is being used, which is the name of the	882	Afterwards it contains the event model that is being used, which is the
643	Perl class implementing the model. This class is usually one of the	883	name of the Perl class implementing the model. This class is usually one
644	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	884	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
645	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	885	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
646		886	will be C<urxvt::anyevent>).
647	The known classes so far are:
648
649	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
650	AnyEvent::Impl::Event based on Event, second best choice.
651	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
652	AnyEvent::Impl::Glib based on Glib, third-best choice.
653	AnyEvent::Impl::Tk based on Tk, very bad choice.
654	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
655	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
656	AnyEvent::Impl::POE based on POE, not generic enough for full support.
657
658	There is no support for WxWidgets, as WxWidgets has no support for
659	watching file handles. However, you can use WxWidgets through the
660	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
661	second, which was considered to be too horrible to even consider for
662	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
663	it's adaptor.
664
665	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
666	autodetecting them.
667		887
668	=item AnyEvent::detect	888	=item AnyEvent::detect
669		889
670	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	890	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
671	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
672	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
673	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>.
674		897
675	=item $guard = AnyEvent::post_detect { BLOCK }	898	=item $guard = AnyEvent::post_detect { BLOCK }
676		899
677	Arranges for the code block to be executed as soon as the event model is	900	Arranges for the code block to be executed as soon as the event model is
678	autodetected (or immediately if this has already happened).	901	autodetected (or immediately if this has already happened).
679		902
		903	The block will be executed I<after> the actual backend has been detected
		904	(C<$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
680	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
681	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
682	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 ||= $guard;
683		934
684	=item @AnyEvent::post_detect	935	=item @AnyEvent::post_detect
685		936
686	If there are any code references in this array (you can C<push> to it	937	If there are any code references in this array (you can C<push> to it
687	before or after loading AnyEvent), then they will called directly after	938	before or after loading AnyEvent), then they will called directly after
688	the event loop has been chosen.	939	the event loop has been chosen.
689		940
690	You should check C<$AnyEvent::MODEL> before adding to this array, though:	941	You should check C<$AnyEvent::MODEL> before adding to this array, though:
691	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
692	and the array will be ignored.	943	array will be ignored.
693		944
694	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.
695		952
696	=back	953	=back
697		954
698	=head1 WHAT TO DO IN A MODULE	955	=head1 WHAT TO DO IN A MODULE
699		956
…		…
754		1011
755		1012
756	=head1 OTHER MODULES	1013	=head1 OTHER MODULES
757		1014
758	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
759	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
760	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
761	available via CPAN.	1018	come with AnyEvent, most are available via CPAN.
762		1019
763	=over 4	1020	=over 4
764		1021
765	=item L<AnyEvent::Util>	1022	=item L<AnyEvent::Util>
766		1023
…		…
775		1032
776	=item L<AnyEvent::Handle>	1033	=item L<AnyEvent::Handle>
777		1034
778	Provide read and write buffers, manages watchers for reads and writes,	1035	Provide read and write buffers, manages watchers for reads and writes,
779	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
780	non-blocking SSL/TLS.	1037	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
781		1038
782	=item L<AnyEvent::DNS>	1039	=item L<AnyEvent::DNS>
783		1040
784	Provides rich asynchronous DNS resolver capabilities.	1041	Provides rich asynchronous DNS resolver capabilities.
785		1042
…		…
813		1070
814	=item L<AnyEvent::GPSD>	1071	=item L<AnyEvent::GPSD>
815		1072
816	A non-blocking interface to gpsd, a daemon delivering GPS information.	1073	A non-blocking interface to gpsd, a daemon delivering GPS information.
817		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
818	=item L<AnyEvent::IGS>	1084	=item L<AnyEvent::IGS>
819		1085
820	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
821	L<App::IGS>).	1087	L<App::IGS>).
822		1088
823	=item L<Net::IRC3>
824
825	AnyEvent based IRC client module family.
826
827	=item L<Net::XMPP2>
828
829	AnyEvent based XMPP (Jabber protocol) module family.
830
831	=item L<Net::FCP>	1089	=item L<Net::FCP>
832		1090
833	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1091	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
834	of AnyEvent.	1092	of AnyEvent.
835		1093
…		…
839		1097
840	=item L<Coro>	1098	=item L<Coro>
841		1099
842	Has special support for AnyEvent via L<Coro::AnyEvent>.	1100	Has special support for AnyEvent via L<Coro::AnyEvent>.
843		1101
844	=item L<IO::Lambda>
845
846	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
847
848	=back	1102	=back
849		1103
850	=cut	1104	=cut
851		1105
852	package AnyEvent;	1106	package AnyEvent;
853		1107
		1108	# basically a tuned-down version of common::sense
		1109	sub common_sense {
854	no warnings;	1110	# no warnings
855	use strict;	1111	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1112	# use strict vars subs
		1113	$^H |= 0x00000600;
		1114	}
856		1115
		1116	BEGIN { AnyEvent::common_sense }
		1117
857	use Carp;	1118	use Carp ();
858		1119
859	our $VERSION = 4.23;	1120	our $VERSION = 4.92;
860	our $MODEL;	1121	our $MODEL;
861		1122
862	our $AUTOLOAD;	1123	our $AUTOLOAD;
863	our @ISA;	1124	our @ISA;
864		1125
865	our @REGISTRY;	1126	our @REGISTRY;
866		1127
867	our $WIN32;	1128	our $WIN32;
868		1129
		1130	our $VERBOSE;
		1131
869	BEGIN {	1132	BEGIN {
870	my $win32 = ! ! ($^O =~ /mswin32/i);	1133	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
871	eval "sub WIN32(){ $win32 }";	1134	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
872	}
873		1135
		1136	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1137	if ${^TAINT};
		1138
874	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1139	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1140
		1141	}
		1142
		1143	our $MAX_SIGNAL_LATENCY = 10;
875		1144
876	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1145	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
877		1146
878	{	1147	{
879	my $idx;	1148	my $idx;
…		…
881	for reverse split /\s*,\s*/,	1150	for reverse split /\s*,\s*/,
882	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1151	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
883	}	1152	}
884		1153
885	my @models = (	1154	my @models = (
886	[EV:: => AnyEvent::Impl::EV::],	1155	[EV:: => AnyEvent::Impl::EV:: , 1],
887	[Event:: => AnyEvent::Impl::Event::],
888	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1156	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
889	# everything below here will not be autoprobed	1157	# everything below here will not (normally) be autoprobed
890	# as the pureperl backend should work everywhere	1158	# as the pureperl backend should work everywhere
891	# and is usually faster	1159	# and is usually faster
		1160	[Event:: => AnyEvent::Impl::Event::, 1],
		1161	[Glib:: => AnyEvent::Impl::Glib:: , 1], # becomes extremely slow with many watchers
		1162	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1163	[Irssi:: => AnyEvent::Impl::Irssi::], # Irssi has a bogus "Event" package
892	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1164	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
893	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
894	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
895	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1165	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
896	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1166	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
897	[Wx:: => AnyEvent::Impl::POE::],	1167	[Wx:: => AnyEvent::Impl::POE::],
898	[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
899	);	1176	);
900		1177
901	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1178	our %method = map +($_ => 1),
		1179	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
902		1180
903	our @post_detect;	1181	our @post_detect;
904		1182
905	sub post_detect(&) {	1183	sub post_detect(&) {
906	my ($cb) = @_;	1184	my ($cb) = @_;
907		1185
908	if ($MODEL) {	1186	if ($MODEL) {
909	$cb->();	1187	$cb->();
910		1188
911	1	1189	undef
912	} else {	1190	} else {
913	push @post_detect, $cb;	1191	push @post_detect, $cb;
914		1192
915	defined wantarray	1193	defined wantarray
916	? bless \$cb, "AnyEvent::Util::PostDetect"	1194	? bless \$cb, "AnyEvent::Util::postdetect"
917	: ()	1195	: ()
918	}	1196	}
919	}	1197	}
920		1198
921	sub AnyEvent::Util::PostDetect::DESTROY {	1199	sub AnyEvent::Util::postdetect::DESTROY {
922	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1200	@post_detect = grep $_ != ${$_[0]}, @post_detect;
923	}	1201	}
924		1202
925	sub detect() {	1203	sub detect() {
926	unless ($MODEL) {	1204	unless ($MODEL) {
927	no strict 'refs';
928	local $SIG{__DIE__};	1205	local $SIG{__DIE__};
929		1206
930	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1207	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
931	my $model = "AnyEvent::Impl::$1";	1208	my $model = "AnyEvent::Impl::$1";
932	if (eval "require $model") {	1209	if (eval "require $model") {
933	$MODEL = $model;	1210	$MODEL = $model;
934	warn "AnyEvent: loaded model '$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 $VERBOSE >= 2;
935	} else {	1212	} else {
936	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1213	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
937	}	1214	}
938	}	1215	}
939		1216
940	# check for already loaded models	1217	# check for already loaded models
941	unless ($MODEL) {	1218	unless ($MODEL) {
942	for (@REGISTRY, @models) {	1219	for (@REGISTRY, @models) {
943	my ($package, $model) = @$_;	1220	my ($package, $model) = @$_;
944	if (${"$package\::VERSION"} > 0) {	1221	if (${"$package\::VERSION"} > 0) {
945	if (eval "require $model") {	1222	if (eval "require $model") {
946	$MODEL = $model;	1223	$MODEL = $model;
947	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1224	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
948	last;	1225	last;
949	}	1226	}
950	}	1227	}
951	}	1228	}
952		1229
953	unless ($MODEL) {	1230	unless ($MODEL) {
954	# try to load a model	1231	# try to autoload a model
955
956	for (@REGISTRY, @models) {	1232	for (@REGISTRY, @models) {
957	my ($package, $model) = @$_;	1233	my ($package, $model, $autoload) = @$_;
		1234	if (
		1235	$autoload
958	if (eval "require $package"	1236	and eval "require $package"
959	and ${"$package\::VERSION"} > 0	1237	and ${"$package\::VERSION"} > 0
960	and eval "require $model") {	1238	and eval "require $model"
		1239	) {
961	$MODEL = $model;	1240	$MODEL = $model;
962	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1241	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
963	last;	1242	last;
964	}	1243	}
965	}	1244	}
966		1245
967	$MODEL	1246	$MODEL
968	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1247	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
969	}	1248	}
970	}	1249	}
971		1250
972	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1251	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
973		1252
…		…
983		1262
984	sub AUTOLOAD {	1263	sub AUTOLOAD {
985	(my $func = $AUTOLOAD) =~ s/.*://;	1264	(my $func = $AUTOLOAD) =~ s/.*://;
986		1265
987	$method{$func}	1266	$method{$func}
988	or croak "$func: not a valid method for AnyEvent objects";	1267	or Carp::croak "$func: not a valid method for AnyEvent objects";
989		1268
990	detect unless $MODEL;	1269	detect unless $MODEL;
991		1270
992	my $class = shift;	1271	my $class = shift;
993	$class->$func (@_);	1272	$class->$func (@_);
994	}	1273	}
995		1274
996	# 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
997	# to support binding more than one watcher per filehandle (they usually	1276	# to support binding more than one watcher per filehandle (they usually
998	# 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).
999	sub _dupfh($$$$) {	1278	sub _dupfh($$;$$) {
1000	my ($poll, $fh, $r, $w) = @_;	1279	my ($poll, $fh, $r, $w) = @_;
1001		1280
1002	require Fcntl;
1003
1004	# cygwin requires the fh mode to be matching, unix doesn't	1281	# cygwin requires the fh mode to be matching, unix doesn't
1005	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1282	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1006	: $poll eq "w" ? ($w, ">")
1007	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1008		1283
1009	open my $fh2, "$mode&" . fileno $fh	1284	open my $fh2, $mode, $fh
1010	or die "cannot dup() filehandle: $!";	1285	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1011		1286
1012	# we assume CLOEXEC is already set by perl in all important cases	1287	# we assume CLOEXEC is already set by perl in all important cases
1013		1288
1014	($fh2, $rw)	1289	($fh2, $rw)
1015	}	1290	}
1016		1291
		1292	#############################################################################
		1293	# "new" API, currently only emulation of it
		1294	#############################################################################
		1295
		1296	package AE;
		1297
		1298	our $VERSION = $AnyEvent::VERSION;
		1299
		1300	sub io($$$) {
		1301	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1302	}
		1303
		1304	sub timer($$$) {
		1305	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2]);
		1306	}
		1307
		1308	sub signal($$) {
		1309	AnyEvent->signal (signal => $_[0], cb => $_[1]);
		1310	}
		1311
		1312	sub child($$) {
		1313	AnyEvent->child (pid => $_[0], cb => $_[1]);
		1314	}
		1315
		1316	sub idle($) {
		1317	AnyEvent->idle (cb => $_[0]);
		1318	}
		1319
		1320	sub cv(;&) {
		1321	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1322	}
		1323
		1324	sub now() {
		1325	AnyEvent->now
		1326	}
		1327
		1328	sub now_update() {
		1329	AnyEvent->now_update
		1330	}
		1331
		1332	sub time() {
		1333	AnyEvent->time
		1334	}
		1335
1017	package AnyEvent::Base;	1336	package AnyEvent::Base;
1018		1337
1019	# default implementation for now and time	1338	# default implementations for many methods
1020		1339
1021	use Time::HiRes ();	1340	sub _time {
		1341	# probe for availability of Time::HiRes
		1342	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1343	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1344	*_time = \&Time::HiRes::time;
		1345	# if (eval "use POSIX (); (POSIX::times())...
		1346	} else {
		1347	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1348	*_time = sub { time }; # epic fail
		1349	}
1022		1350
1023	sub time { Time::HiRes::time }	1351	&_time
1024	sub now { Time::HiRes::time }	1352	}
		1353
		1354	sub time { _time }
		1355	sub now { _time }
		1356	sub now_update { }
1025		1357
1026	# default implementation for ->condvar	1358	# default implementation for ->condvar
1027		1359
1028	sub condvar {	1360	sub condvar {
1029	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1361	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1030	}	1362	}
1031		1363
1032	# default implementation for ->signal	1364	# default implementation for ->signal
1033		1365
1034	our %SIG_CB;	1366	our $HAVE_ASYNC_INTERRUPT;
		1367
		1368	sub _have_async_interrupt() {
		1369	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1370	&& eval "use Async::Interrupt 1.0 (); 1")
		1371	unless defined $HAVE_ASYNC_INTERRUPT;
		1372
		1373	$HAVE_ASYNC_INTERRUPT
		1374	}
		1375
		1376	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1377	our (%SIG_ASY, %SIG_ASY_W);
		1378	our ($SIG_COUNT, $SIG_TW);
		1379
		1380	sub _signal_exec {
		1381	$HAVE_ASYNC_INTERRUPT
		1382	? $SIGPIPE_R->drain
		1383	: sysread $SIGPIPE_R, my $dummy, 9;
		1384
		1385	while (%SIG_EV) {
		1386	for (keys %SIG_EV) {
		1387	delete $SIG_EV{$_};
		1388	$_->() for values %{ $SIG_CB{$_} || {} };
		1389	}
		1390	}
		1391	}
		1392
		1393	# install a dummy wakeup watcher to reduce signal catching latency
		1394	sub _sig_add() {
		1395	unless ($SIG_COUNT++) {
		1396	# try to align timer on a full-second boundary, if possible
		1397	my $NOW = AE::now;
		1398
		1399	$SIG_TW = AE::timer
		1400	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1401	$MAX_SIGNAL_LATENCY,
		1402	sub { } # just for the PERL_ASYNC_CHECK
		1403	;
		1404	}
		1405	}
		1406
		1407	sub _sig_del {
		1408	undef $SIG_TW
		1409	unless --$SIG_COUNT;
		1410	}
		1411
		1412	our $_sig_name_init; $_sig_name_init = sub {
		1413	eval q{ # poor man's autoloading
		1414	undef $_sig_name_init;
		1415
		1416	if (_have_async_interrupt) {
		1417	*sig2num = \&Async::Interrupt::sig2num;
		1418	*sig2name = \&Async::Interrupt::sig2name;
		1419	} else {
		1420	require Config;
		1421
		1422	my %signame2num;
		1423	@signame2num{ split ' ', $Config::Config{sig_name} }
		1424	= split ' ', $Config::Config{sig_num};
		1425
		1426	my @signum2name;
		1427	@signum2name[values %signame2num] = keys %signame2num;
		1428
		1429	*sig2num = sub($) {
		1430	$_[0] > 0 ? shift : $signame2num{+shift}
		1431	};
		1432	*sig2name = sub ($) {
		1433	$_[0] > 0 ? $signum2name[+shift] : shift
		1434	};
		1435	}
		1436	};
		1437	die if $@;
		1438	};
		1439
		1440	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1441	sub sig2name($) { &$_sig_name_init; &sig2name }
1035		1442
1036	sub signal {	1443	sub signal {
		1444	eval q{ # poor man's autoloading {}
		1445	# probe for availability of Async::Interrupt
		1446	if (_have_async_interrupt) {
		1447	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1448
		1449	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1450	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1451
		1452	} else {
		1453	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1454
		1455	require Fcntl;
		1456
		1457	if (AnyEvent::WIN32) {
		1458	require AnyEvent::Util;
		1459
		1460	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1461	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1462	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1463	} else {
		1464	pipe $SIGPIPE_R, $SIGPIPE_W;
		1465	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1466	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1467
		1468	# not strictly required, as $^F is normally 2, but let's make sure...
		1469	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1470	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1471	}
		1472
		1473	$SIGPIPE_R
		1474	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1475
		1476	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1477	}
		1478
		1479	*signal = sub {
1037	my (undef, %arg) = @_;	1480	my (undef, %arg) = @_;
1038		1481
1039	my $signal = uc $arg{signal}	1482	my $signal = uc $arg{signal}
1040	or Carp::croak "required option 'signal' is missing";	1483	or Carp::croak "required option 'signal' is missing";
1041		1484
		1485	if ($HAVE_ASYNC_INTERRUPT) {
		1486	# async::interrupt
		1487
		1488	$signal = sig2num $signal;
1042	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1489	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1490
		1491	$SIG_ASY{$signal} ||= new Async::Interrupt
		1492	cb => sub { undef $SIG_EV{$signal} },
		1493	signal => $signal,
		1494	pipe => [$SIGPIPE_R->filenos],
		1495	pipe_autodrain => 0,
		1496	;
		1497
		1498	} else {
		1499	# pure perl
		1500
		1501	# AE::Util has been loaded in signal
		1502	$signal = sig2name $signal;
		1503	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1504
1043	$SIG{$signal} ||= sub {	1505	$SIG{$signal} ||= sub {
1044	$_->() for values %{ $SIG_CB{$signal} || {} };	1506	local $!;
		1507	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1508	undef $SIG_EV{$signal};
		1509	};
		1510
		1511	# can't do signal processing without introducing races in pure perl,
		1512	# so limit the signal latency.
		1513	_sig_add;
		1514	}
		1515
		1516	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1517	};
		1518
		1519	*AnyEvent::Base::signal::DESTROY = sub {
		1520	my ($signal, $cb) = @{$_[0]};
		1521
		1522	_sig_del;
		1523
		1524	delete $SIG_CB{$signal}{$cb};
		1525
		1526	$HAVE_ASYNC_INTERRUPT
		1527	? delete $SIG_ASY{$signal}
		1528	: # delete doesn't work with older perls - they then
		1529	# print weird messages, or just unconditionally exit
		1530	# instead of getting the default action.
		1531	undef $SIG{$signal}
		1532	unless keys %{ $SIG_CB{$signal} };
		1533	};
1045	};	1534	};
1046		1535	die if $@;
1047	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1536	&signal
1048	}
1049
1050	sub AnyEvent::Base::Signal::DESTROY {
1051	my ($signal, $cb) = @{$_[0]};
1052
1053	delete $SIG_CB{$signal}{$cb};
1054
1055	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1056	}	1537	}
1057		1538
1058	# default implementation for ->child	1539	# default implementation for ->child
1059		1540
1060	our %PID_CB;	1541	our %PID_CB;
1061	our $CHLD_W;	1542	our $CHLD_W;
1062	our $CHLD_DELAY_W;	1543	our $CHLD_DELAY_W;
1063	our $PID_IDLE;
1064	our $WNOHANG;	1544	our $WNOHANG;
1065		1545
1066	sub _child_wait {	1546	sub _emit_childstatus($$) {
1067	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1547	my (undef, $rpid, $rstatus) = @_;
		1548
		1549	$_->($rpid, $rstatus)
1068	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1550	for values %{ $PID_CB{$rpid} || {} },
1069	(values %{ $PID_CB{0} || {} });	1551	values %{ $PID_CB{0} || {} };
1070	}
1071
1072	undef $PID_IDLE;
1073	}	1552	}
1074		1553
1075	sub _sigchld {	1554	sub _sigchld {
1076	# make sure we deliver these changes "synchronous" with the event loop.	1555	my $pid;
1077	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1556
1078	undef $CHLD_DELAY_W;	1557	AnyEvent->_emit_childstatus ($pid, $?)
1079	&_child_wait;	1558	while ($pid = waitpid -1, $WNOHANG) > 0;
1080	});
1081	}	1559	}
1082		1560
1083	sub child {	1561	sub child {
1084	my (undef, %arg) = @_;	1562	my (undef, %arg) = @_;
1085		1563
1086	defined (my $pid = $arg{pid} + 0)	1564	defined (my $pid = $arg{pid} + 0)
1087	or Carp::croak "required option 'pid' is missing";	1565	or Carp::croak "required option 'pid' is missing";
1088		1566
1089	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1567	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1090		1568
1091	unless ($WNOHANG) {	1569	# WNOHANG is almost cetrainly 1 everywhere
		1570	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1571	? 1
1092	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1572	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1093	}
1094		1573
1095	unless ($CHLD_W) {	1574	unless ($CHLD_W) {
1096	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1575	$CHLD_W = AE::signal CHLD => \&_sigchld;
1097	# child could be a zombie already, so make at least one round	1576	# child could be a zombie already, so make at least one round
1098	&_sigchld;	1577	&_sigchld;
1099	}	1578	}
1100		1579
1101	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1580	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1102	}	1581	}
1103		1582
1104	sub AnyEvent::Base::Child::DESTROY {	1583	sub AnyEvent::Base::child::DESTROY {
1105	my ($pid, $cb) = @{$_[0]};	1584	my ($pid, $cb) = @{$_[0]};
1106		1585
1107	delete $PID_CB{$pid}{$cb};	1586	delete $PID_CB{$pid}{$cb};
1108	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1587	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1109		1588
1110	undef $CHLD_W unless keys %PID_CB;	1589	undef $CHLD_W unless keys %PID_CB;
1111	}	1590	}
1112		1591
		1592	# idle emulation is done by simply using a timer, regardless
		1593	# of whether the process is idle or not, and not letting
		1594	# the callback use more than 50% of the time.
		1595	sub idle {
		1596	my (undef, %arg) = @_;
		1597
		1598	my ($cb, $w, $rcb) = $arg{cb};
		1599
		1600	$rcb = sub {
		1601	if ($cb) {
		1602	$w = _time;
		1603	&$cb;
		1604	$w = _time - $w;
		1605
		1606	# never use more then 50% of the time for the idle watcher,
		1607	# within some limits
		1608	$w = 0.0001 if $w < 0.0001;
		1609	$w = 5 if $w > 5;
		1610
		1611	$w = AE::timer $w, 0, $rcb;
		1612	} else {
		1613	# clean up...
		1614	undef $w;
		1615	undef $rcb;
		1616	}
		1617	};
		1618
		1619	$w = AE::timer 0.05, 0, $rcb;
		1620
		1621	bless \\$cb, "AnyEvent::Base::idle"
		1622	}
		1623
		1624	sub AnyEvent::Base::idle::DESTROY {
		1625	undef $${$_[0]};
		1626	}
		1627
1113	package AnyEvent::CondVar;	1628	package AnyEvent::CondVar;
1114		1629
1115	our @ISA = AnyEvent::CondVar::Base::;	1630	our @ISA = AnyEvent::CondVar::Base::;
1116		1631
1117	package AnyEvent::CondVar::Base;	1632	package AnyEvent::CondVar::Base;
1118		1633
1119	use overload	1634	#use overload
1120	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1635	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1121	fallback => 1;	1636	# fallback => 1;
		1637
		1638	# save 300+ kilobytes by dirtily hardcoding overloading
		1639	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1640	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1641	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1642	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1643
		1644	our $WAITING;
1122		1645
1123	sub _send {	1646	sub _send {
1124	# nop	1647	# nop
1125	}	1648	}
1126		1649
…		…
1139	sub ready {	1662	sub ready {
1140	$_[0]{_ae_sent}	1663	$_[0]{_ae_sent}
1141	}	1664	}
1142		1665
1143	sub _wait {	1666	sub _wait {
		1667	$WAITING
		1668	and !$_[0]{_ae_sent}
		1669	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1670
		1671	local $WAITING = 1;
1144	AnyEvent->one_event while !$_[0]{_ae_sent};	1672	AnyEvent->one_event while !$_[0]{_ae_sent};
1145	}	1673	}
1146		1674
1147	sub recv {	1675	sub recv {
1148	$_[0]->_wait;	1676	$_[0]->_wait;
…		…
1150	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1678	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1151	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1679	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1152	}	1680	}
1153		1681
1154	sub cb {	1682	sub cb {
1155	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1683	my $cv = shift;
		1684
		1685	@_
		1686	and $cv->{_ae_cb} = shift
		1687	and $cv->{_ae_sent}
		1688	and (delete $cv->{_ae_cb})->($cv);
		1689
1156	$_[0]{_ae_cb}	1690	$cv->{_ae_cb}
1157	}	1691	}
1158		1692
1159	sub begin {	1693	sub begin {
1160	++$_[0]{_ae_counter};	1694	++$_[0]{_ae_counter};
1161	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1695	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1167	}	1701	}
1168		1702
1169	# undocumented/compatibility with pre-3.4	1703	# undocumented/compatibility with pre-3.4
1170	*broadcast = \&send;	1704	*broadcast = \&send;
1171	*wait = \&_wait;	1705	*wait = \&_wait;
		1706
		1707	=head1 ERROR AND EXCEPTION HANDLING
		1708
		1709	In general, AnyEvent does not do any error handling - it relies on the
		1710	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1711	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1712	checking of all AnyEvent methods, however, which is highly useful during
		1713	development.
		1714
		1715	As for exception handling (i.e. runtime errors and exceptions thrown while
		1716	executing a callback), this is not only highly event-loop specific, but
		1717	also not in any way wrapped by this module, as this is the job of the main
		1718	program.
		1719
		1720	The pure perl event loop simply re-throws the exception (usually
		1721	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1722	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1723	so on.
		1724
		1725	=head1 ENVIRONMENT VARIABLES
		1726
		1727	The following environment variables are used by this module or its
		1728	submodules.
		1729
		1730	Note that AnyEvent will remove I<all> environment variables starting with
		1731	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1732	enabled.
		1733
		1734	=over 4
		1735
		1736	=item C<PERL_ANYEVENT_VERBOSE>
		1737
		1738	By default, AnyEvent will be completely silent except in fatal
		1739	conditions. You can set this environment variable to make AnyEvent more
		1740	talkative.
		1741
		1742	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1743	conditions, such as not being able to load the event model specified by
		1744	C<PERL_ANYEVENT_MODEL>.
		1745
		1746	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1747	model it chooses.
		1748
		1749	When set to C<8> or higher, then AnyEvent will report extra information on
		1750	which optional modules it loads and how it implements certain features.
		1751
		1752	=item C<PERL_ANYEVENT_STRICT>
		1753
		1754	AnyEvent does not do much argument checking by default, as thorough
		1755	argument checking is very costly. Setting this variable to a true value
		1756	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1757	check the arguments passed to most method calls. If it finds any problems,
		1758	it will croak.
		1759
		1760	In other words, enables "strict" mode.
		1761
		1762	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1763	>>, it is definitely recommended to keep it off in production. Keeping
		1764	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1765	can be very useful, however.
		1766
		1767	=item C<PERL_ANYEVENT_MODEL>
		1768
		1769	This can be used to specify the event model to be used by AnyEvent, before
		1770	auto detection and -probing kicks in. It must be a string consisting
		1771	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1772	and the resulting module name is loaded and if the load was successful,
		1773	used as event model. If it fails to load AnyEvent will proceed with
		1774	auto detection and -probing.
		1775
		1776	This functionality might change in future versions.
		1777
		1778	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1779	could start your program like this:
		1780
		1781	PERL_ANYEVENT_MODEL=Perl perl ...
		1782
		1783	=item C<PERL_ANYEVENT_PROTOCOLS>
		1784
		1785	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1786	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1787	of auto probing).
		1788
		1789	Must be set to a comma-separated list of protocols or address families,
		1790	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1791	used, and preference will be given to protocols mentioned earlier in the
		1792	list.
		1793
		1794	This variable can effectively be used for denial-of-service attacks
		1795	against local programs (e.g. when setuid), although the impact is likely
		1796	small, as the program has to handle conenction and other failures anyways.
		1797
		1798	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1799	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1800	- only support IPv4, never try to resolve or contact IPv6
		1801	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1802	IPv6, but prefer IPv6 over IPv4.
		1803
		1804	=item C<PERL_ANYEVENT_EDNS0>
		1805
		1806	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1807	for DNS. This extension is generally useful to reduce DNS traffic, but
		1808	some (broken) firewalls drop such DNS packets, which is why it is off by
		1809	default.
		1810
		1811	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1812	EDNS0 in its DNS requests.
		1813
		1814	=item C<PERL_ANYEVENT_MAX_FORKS>
		1815
		1816	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1817	will create in parallel.
		1818
		1819	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1820
		1821	The default value for the C<max_outstanding> parameter for the default DNS
		1822	resolver - this is the maximum number of parallel DNS requests that are
		1823	sent to the DNS server.
		1824
		1825	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1826
		1827	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1828	configuration) in the default resolver. When set to the empty string, no
		1829	default config will be used.
		1830
		1831	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1832
		1833	When neither C<ca_file> nor C<ca_path> was specified during
		1834	L<AnyEvent::TLS> context creation, and either of these environment
		1835	variables exist, they will be used to specify CA certificate locations
		1836	instead of a system-dependent default.
		1837
		1838	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1839
		1840	When these are set to C<1>, then the respective modules are not
		1841	loaded. Mostly good for testing AnyEvent itself.
		1842
		1843	=back
1172		1844
1173	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1845	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1174		1846
1175	This is an advanced topic that you do not normally need to use AnyEvent in	1847	This is an advanced topic that you do not normally need to use AnyEvent in
1176	a module. This section is only of use to event loop authors who want to	1848	a module. This section is only of use to event loop authors who want to
…		…
1210		1882
1211	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1883	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1212	condition variables: code blocking while waiting for a condition will	1884	condition variables: code blocking while waiting for a condition will
1213	C<die>. This still works with most modules/usages, and blocking calls must	1885	C<die>. This still works with most modules/usages, and blocking calls must
1214	not be done in an interactive application, so it makes sense.	1886	not be done in an interactive application, so it makes sense.
1215
1216	=head1 ENVIRONMENT VARIABLES
1217
1218	The following environment variables are used by this module:
1219
1220	=over 4
1221
1222	=item C<PERL_ANYEVENT_VERBOSE>
1223
1224	By default, AnyEvent will be completely silent except in fatal
1225	conditions. You can set this environment variable to make AnyEvent more
1226	talkative.
1227
1228	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1229	conditions, such as not being able to load the event model specified by
1230	C<PERL_ANYEVENT_MODEL>.
1231
1232	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1233	model it chooses.
1234
1235	=item C<PERL_ANYEVENT_STRICT>
1236
1237	AnyEvent does not do much argument checking by default, as thorough
1238	argument checking is very costly. Setting this variable to a true value
1239	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1240	check the arguments passed to most method calls. If it finds any problems
1241	it will croak.
1242
1243	In other words, enables "strict" mode.
1244
1245	Unlike C<use strict> it is definitely recommended ot keep it off in
1246	production.
1247
1248	=item C<PERL_ANYEVENT_MODEL>
1249
1250	This can be used to specify the event model to be used by AnyEvent, before
1251	auto detection and -probing kicks in. It must be a string consisting
1252	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1253	and the resulting module name is loaded and if the load was successful,
1254	used as event model. If it fails to load AnyEvent will proceed with
1255	auto detection and -probing.
1256
1257	This functionality might change in future versions.
1258
1259	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1260	could start your program like this:
1261
1262	PERL_ANYEVENT_MODEL=Perl perl ...
1263
1264	=item C<PERL_ANYEVENT_PROTOCOLS>
1265
1266	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1267	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1268	of auto probing).
1269
1270	Must be set to a comma-separated list of protocols or address families,
1271	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1272	used, and preference will be given to protocols mentioned earlier in the
1273	list.
1274
1275	This variable can effectively be used for denial-of-service attacks
1276	against local programs (e.g. when setuid), although the impact is likely
1277	small, as the program has to handle connection errors already-
1278
1279	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1280	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1281	- only support IPv4, never try to resolve or contact IPv6
1282	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1283	IPv6, but prefer IPv6 over IPv4.
1284
1285	=item C<PERL_ANYEVENT_EDNS0>
1286
1287	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1288	for DNS. This extension is generally useful to reduce DNS traffic, but
1289	some (broken) firewalls drop such DNS packets, which is why it is off by
1290	default.
1291
1292	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1293	EDNS0 in its DNS requests.
1294
1295	=item C<PERL_ANYEVENT_MAX_FORKS>
1296
1297	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1298	will create in parallel.
1299
1300	=back
1301		1887
1302	=head1 EXAMPLE PROGRAM	1888	=head1 EXAMPLE PROGRAM
1303		1889
1304	The following program uses an I/O watcher to read data from STDIN, a timer	1890	The following program uses an I/O watcher to read data from STDIN, a timer
1305	to display a message once per second, and a condition variable to quit the	1891	to display a message once per second, and a condition variable to quit the
…		…
1499	watcher.	2085	watcher.
1500		2086
1501	=head3 Results	2087	=head3 Results
1502		2088
1503	name watchers bytes create invoke destroy comment	2089	name watchers bytes create invoke destroy comment
1504	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2090	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1505	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2091	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1506	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2092	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1507	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2093	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1508	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2094	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1509	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2095	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		2096	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		2097	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1510	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2098	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1511	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2099	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1512	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2100	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1513	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2101	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1514		2102
1515	=head3 Discussion	2103	=head3 Discussion
1516		2104
1517	The benchmark does I<not> measure scalability of the event loop very	2105	The benchmark does I<not> measure scalability of the event loop very
1518	well. For example, a select-based event loop (such as the pure perl one)	2106	well. For example, a select-based event loop (such as the pure perl one)
…		…
1543	performance becomes really bad with lots of file descriptors (and few of	2131	performance becomes really bad with lots of file descriptors (and few of
1544	them active), of course, but this was not subject of this benchmark.	2132	them active), of course, but this was not subject of this benchmark.
1545		2133
1546	The C<Event> module has a relatively high setup and callback invocation	2134	The C<Event> module has a relatively high setup and callback invocation
1547	cost, but overall scores in on the third place.	2135	cost, but overall scores in on the third place.
		2136
		2137	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2138	when using its pure perl backend.
1548		2139
1549	C<Glib>'s memory usage is quite a bit higher, but it features a	2140	C<Glib>'s memory usage is quite a bit higher, but it features a
1550	faster callback invocation and overall ends up in the same class as	2141	faster callback invocation and overall ends up in the same class as
1551	C<Event>. However, Glib scales extremely badly, doubling the number of	2142	C<Event>. However, Glib scales extremely badly, doubling the number of
1552	watchers increases the processing time by more than a factor of four,	2143	watchers increases the processing time by more than a factor of four,
…		…
1630	it to another server. This includes deleting the old timeout and creating	2221	it to another server. This includes deleting the old timeout and creating
1631	a new one that moves the timeout into the future.	2222	a new one that moves the timeout into the future.
1632		2223
1633	=head3 Results	2224	=head3 Results
1634		2225
1635	name sockets create request	2226	name sockets create request
1636	EV 20000 69.01 11.16	2227	EV 20000 69.01 11.16
1637	Perl 20000 73.32 35.87	2228	Perl 20000 73.32 35.87
		2229	IOAsync 20000 157.00 98.14 epoll
		2230	IOAsync 20000 159.31 616.06 poll
1638	Event 20000 212.62 257.32	2231	Event 20000 212.62 257.32
1639	Glib 20000 651.16 1896.30	2232	Glib 20000 651.16 1896.30
1640	POE 20000 349.67 12317.24 uses POE::Loop::Event	2233	POE 20000 349.67 12317.24 uses POE::Loop::Event
1641		2234
1642	=head3 Discussion	2235	=head3 Discussion
1643		2236
1644	This benchmark I<does> measure scalability and overall performance of the	2237	This benchmark I<does> measure scalability and overall performance of the
1645	particular event loop.	2238	particular event loop.
…		…
1647	EV is again fastest. Since it is using epoll on my system, the setup time	2240	EV is again fastest. Since it is using epoll on my system, the setup time
1648	is relatively high, though.	2241	is relatively high, though.
1649		2242
1650	Perl surprisingly comes second. It is much faster than the C-based event	2243	Perl surprisingly comes second. It is much faster than the C-based event
1651	loops Event and Glib.	2244	loops Event and Glib.
		2245
		2246	IO::Async performs very well when using its epoll backend, and still quite
		2247	good compared to Glib when using its pure perl backend.
1652		2248
1653	Event suffers from high setup time as well (look at its code and you will	2249	Event suffers from high setup time as well (look at its code and you will
1654	understand why). Callback invocation also has a high overhead compared to	2250	understand why). Callback invocation also has a high overhead compared to
1655	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2251	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1656	uses select or poll in basically all documented configurations.	2252	uses select or poll in basically all documented configurations.
…		…
1719	=item * C-based event loops perform very well with small number of	2315	=item * C-based event loops perform very well with small number of
1720	watchers, as the management overhead dominates.	2316	watchers, as the management overhead dominates.
1721		2317
1722	=back	2318	=back
1723		2319
		2320	=head2 THE IO::Lambda BENCHMARK
		2321
		2322	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2323	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2324	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2325	shouldn't come as a surprise to anybody). As such, the benchmark is
		2326	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2327	very optimal. But how would AnyEvent compare when used without the extra
		2328	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2329
		2330	The benchmark itself creates an echo-server, and then, for 500 times,
		2331	connects to the echo server, sends a line, waits for the reply, and then
		2332	creates the next connection. This is a rather bad benchmark, as it doesn't
		2333	test the efficiency of the framework or much non-blocking I/O, but it is a
		2334	benchmark nevertheless.
		2335
		2336	name runtime
		2337	Lambda/select 0.330 sec
		2338	+ optimized 0.122 sec
		2339	Lambda/AnyEvent 0.327 sec
		2340	+ optimized 0.138 sec
		2341	Raw sockets/select 0.077 sec
		2342	POE/select, components 0.662 sec
		2343	POE/select, raw sockets 0.226 sec
		2344	POE/select, optimized 0.404 sec
		2345
		2346	AnyEvent/select/nb 0.085 sec
		2347	AnyEvent/EV/nb 0.068 sec
		2348	+state machine 0.134 sec
		2349
		2350	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2351	benchmarks actually make blocking connects and use 100% blocking I/O,
		2352	defeating the purpose of an event-based solution. All of the newly
		2353	written AnyEvent benchmarks use 100% non-blocking connects (using
		2354	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2355	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2356	generally require a lot more bookkeeping and event handling than blocking
		2357	connects (which involve a single syscall only).
		2358
		2359	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2360	offers similar expressive power as POE and IO::Lambda, using conventional
		2361	Perl syntax. This means that both the echo server and the client are 100%
		2362	non-blocking, further placing it at a disadvantage.
		2363
		2364	As you can see, the AnyEvent + EV combination even beats the
		2365	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2366	backend easily beats IO::Lambda and POE.
		2367
		2368	And even the 100% non-blocking version written using the high-level (and
		2369	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2370	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2371	in a non-blocking way.
		2372
		2373	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2374	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2375	part of the IO::lambda distribution and were used without any changes.
		2376
		2377
		2378	=head1 SIGNALS
		2379
		2380	AnyEvent currently installs handlers for these signals:
		2381
		2382	=over 4
		2383
		2384	=item SIGCHLD
		2385
		2386	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2387	emulation for event loops that do not support them natively. Also, some
		2388	event loops install a similar handler.
		2389
		2390	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2391	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2392
		2393	=item SIGPIPE
		2394
		2395	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2396	when AnyEvent gets loaded.
		2397
		2398	The rationale for this is that AnyEvent users usually do not really depend
		2399	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2400	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2401	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2402	some random socket.
		2403
		2404	The rationale for installing a no-op handler as opposed to ignoring it is
		2405	that this way, the handler will be restored to defaults on exec.
		2406
		2407	Feel free to install your own handler, or reset it to defaults.
		2408
		2409	=back
		2410
		2411	=cut
		2412
		2413	undef $SIG{CHLD}
		2414	if $SIG{CHLD} eq 'IGNORE';
		2415
		2416	$SIG{PIPE} = sub { }
		2417	unless defined $SIG{PIPE};
		2418
		2419	=head1 RECOMMENDED/OPTIONAL MODULES
		2420
		2421	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2422	it's built-in modules) are required to use it.
		2423
		2424	That does not mean that AnyEvent won't take advantage of some additional
		2425	modules if they are installed.
		2426
		2427	This section epxlains which additional modules will be used, and how they
		2428	affect AnyEvent's operetion.
		2429
		2430	=over 4
		2431
		2432	=item L<Async::Interrupt>
		2433
		2434	This slightly arcane module is used to implement fast signal handling: To
		2435	my knowledge, there is no way to do completely race-free and quick
		2436	signal handling in pure perl. To ensure that signals still get
		2437	delivered, AnyEvent will start an interval timer to wake up perl (and
		2438	catch the signals) with some delay (default is 10 seconds, look for
		2439	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2440
		2441	If this module is available, then it will be used to implement signal
		2442	catching, which means that signals will not be delayed, and the event loop
		2443	will not be interrupted regularly, which is more efficient (And good for
		2444	battery life on laptops).
		2445
		2446	This affects not just the pure-perl event loop, but also other event loops
		2447	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2448
		2449	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2450	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2451	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2452	does nothing for those backends.
		2453
		2454	=item L<EV>
		2455
		2456	This module isn't really "optional", as it is simply one of the backend
		2457	event loops that AnyEvent can use. However, it is simply the best event
		2458	loop available in terms of features, speed and stability: It supports
		2459	the AnyEvent API optimally, implements all the watcher types in XS, does
		2460	automatic timer adjustments even when no monotonic clock is available,
		2461	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2462	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2463	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2464
		2465	=item L<Guard>
		2466
		2467	The guard module, when used, will be used to implement
		2468	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2469	lot less memory), but otherwise doesn't affect guard operation much. It is
		2470	purely used for performance.
		2471
		2472	=item L<JSON> and L<JSON::XS>
		2473
		2474	This module is required when you want to read or write JSON data via
		2475	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2476	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2477
		2478	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2479	installed.
		2480
		2481	=item L<Net::SSLeay>
		2482
		2483	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2484	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2485	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2486
		2487	=item L<Time::HiRes>
		2488
		2489	This module is part of perl since release 5.008. It will be used when the
		2490	chosen event library does not come with a timing source on it's own. The
		2491	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2492	try to use a monotonic clock for timing stability.
		2493
		2494	=back
		2495
1724		2496
1725	=head1 FORK	2497	=head1 FORK
1726		2498
1727	Most event libraries are not fork-safe. The ones who are usually are	2499	Most event libraries are not fork-safe. The ones who are usually are
1728	because they rely on inefficient but fork-safe C<select> or C<poll>	2500	because they rely on inefficient but fork-safe C<select> or C<poll>
1729	calls. Only L<EV> is fully fork-aware.	2501	calls. Only L<EV> is fully fork-aware.
1730		2502
1731	If you have to fork, you must either do so I<before> creating your first	2503	If you have to fork, you must either do so I<before> creating your first
1732	watcher OR you must not use AnyEvent at all in the child.	2504	watcher OR you must not use AnyEvent at all in the child OR you must do
		2505	something completely out of the scope of AnyEvent.
1733		2506
1734		2507
1735	=head1 SECURITY CONSIDERATIONS	2508	=head1 SECURITY CONSIDERATIONS
1736		2509
1737	AnyEvent can be forced to load any event model via	2510	AnyEvent can be forced to load any event model via
…		…
1749	use AnyEvent;	2522	use AnyEvent;
1750		2523
1751	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2524	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1752	be used to probe what backend is used and gain other information (which is	2525	be used to probe what backend is used and gain other information (which is
1753	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2526	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1754	$ENV{PERL_ANYEGENT_STRICT}.	2527	$ENV{PERL_ANYEVENT_STRICT}.
		2528
		2529	Note that AnyEvent will remove I<all> environment variables starting with
		2530	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2531	enabled.
1755		2532
1756		2533
1757	=head1 BUGS	2534	=head1 BUGS
1758		2535
1759	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2536	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1760	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2537	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1761	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2538	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1762	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2539	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1763	pronounced).	2540	pronounced).
1764		2541
1765		2542
1766	=head1 SEE ALSO	2543	=head1 SEE ALSO
1767		2544
…		…
1771	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2548	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1772		2549
1773	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2550	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1774	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2551	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1775	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2552	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1776	L<AnyEvent::Impl::POE>.	2553	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1777		2554
1778	Non-blocking file handles, sockets, TCP clients and	2555	Non-blocking file handles, sockets, TCP clients and
1779	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2556	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1780		2557
1781	Asynchronous DNS: L<AnyEvent::DNS>.	2558	Asynchronous DNS: L<AnyEvent::DNS>.
1782		2559
1783	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2560	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2561	L<Coro::Event>,
1784		2562
1785	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2563	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2564	L<AnyEvent::HTTP>.
1786		2565
1787		2566
1788	=head1 AUTHOR	2567	=head1 AUTHOR
1789		2568
1790	Marc Lehmann <schmorp@schmorp.de>	2569	Marc Lehmann <schmorp@schmorp.de>

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