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Revision 1.173 by root, Mon Jul 21 03:47:22 2008 UTC vs.
Revision 1.279 by root, Sun Aug 9 16:05:11 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
395	>> method, usually without arguments. The only argument pair allowed is	537	>> method, usually without arguments. The only argument pair allowed is
396
397	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
398	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
399	the results).	540	the results).
400		541
401	After creation, the condition variable is "false" until it becomes "true"	542	After creation, the condition variable is "false" until it becomes "true"
…		…
406	Condition variables are similar to callbacks, except that you can	547	Condition variables are similar to callbacks, except that you can
407	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
408	in time where multiple outstanding events have been processed. And yet	549	in time where multiple outstanding events have been processed. And yet
409	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
410	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
411	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.
412		554
413	Condition variables are very useful to signal that something has finished,	555	Condition variables are very useful to signal that something has finished,
414	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,
415	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
416	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
…		…
450	after => 1,	592	after => 1,
451	cb => sub { $result_ready->send },	593	cb => sub { $result_ready->send },
452	);	594	);
453		595
454	# this "blocks" (while handling events) till the callback	596	# this "blocks" (while handling events) till the callback
455	# calls send	597	# calls -<send
456	$result_ready->recv;	598	$result_ready->recv;
457		599
458	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
459	condition variables are also code references.	601	variables are also callable directly.
460		602
461	my $done = AnyEvent->condvar;	603	my $done = AnyEvent->condvar;
462	my $delay = AnyEvent->timer (after => 5, cb => $done);	604	my $delay = AnyEvent->timer (after => 5, cb => $done);
463	$done->recv;	605	$done->recv;
464		606
…		…
470		612
471	...	613	...
472		614
473	my @info = $couchdb->info->recv;	615	my @info = $couchdb->info->recv;
474		616
475	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
476	results are available:	618	results are available:
477		619
478	$couchdb->info->cb (sub {	620	$couchdb->info->cb (sub {
479	my @info = $_[0]->recv;	621	my @info = $_[0]->recv;
480	});	622	});
…		…
498	immediately from within send.	640	immediately from within send.
499		641
500	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
501	future C<< ->recv >> calls.	643	future C<< ->recv >> calls.
502		644
503	Condition variables are overloaded so one can call them directly	645	Condition variables are overloaded so one can call them directly (as if
504	(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
505	C<send>. Note, however, that many C-based event loops do not handle	647	C<send>.
506	overloading, so as tempting as it may be, passing a condition variable
507	instead of a callback does not work. Both the pure perl and EV loops
508	support overloading, however, as well as all functions that use perl to
509	invoke a callback (as in L<AnyEvent::Socket> and L<AnyEvent::DNS> for
510	example).
511		648
512	=item $cv->croak ($error)	649	=item $cv->croak ($error)
513		650
514	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
515	C<Carp::croak> with the given error message/object/scalar.	652	C<Carp::croak> with the given error message/object/scalar.
516		653
517	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
518	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.
519		660
520	=item $cv->begin ([group callback])	661	=item $cv->begin ([group callback])
521		662
522	=item $cv->end	663	=item $cv->end
523
524	These two methods are EXPERIMENTAL and MIGHT CHANGE.
525		664
526	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
527	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
528	to use a condition variable for the whole process.	667	to use a condition variable for the whole process.
529		668
…		…
531	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
532	>>, 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
533	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
534	callback was set, C<send> will be called without any arguments.	673	callback was set, C<send> will be called without any arguments.
535		674
536	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:
537		706
538	my $cv = AnyEvent->condvar;	707	my $cv = AnyEvent->condvar;
539		708
540	my %result;	709	my %result;
541	$cv->begin (sub { $cv->send (\%result) });	710	$cv->begin (sub { $cv->send (\%result) });
…		…
561	loop, which serves two important purposes: first, it sets the callback	730	loop, which serves two important purposes: first, it sets the callback
562	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
563	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
564	doesn't execute once).	733	doesn't execute once).
565		734
566	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
567	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
568	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
569	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>.
570		740
571	=back	741	=back
572		742
573	=head3 METHODS FOR CONSUMERS	743	=head3 METHODS FOR CONSUMERS
574		744
…		…
590	function will call C<croak>.	760	function will call C<croak>.
591		761
592	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,
593	in scalar context only the first one will be returned.	763	in scalar context only the first one will be returned.
594		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
595	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
596	(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
597	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
598	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
599	condition variables with some kind of request results and supporting	776	condition variables with some kind of request results and supporting
600	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,
601	while still supporting blocking waits if the caller so desires).	778	while still supporting blocking waits if the caller so desires).
602		779
603	Another reason I<never> to C<< ->recv >> in a module is that you cannot
604	sensibly have two C<< ->recv >>'s in parallel, as that would require
605	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
606	can supply.
607
608	The L<Coro> module, however, I<can> and I<does> supply coroutines and, in
609	fact, L<Coro::AnyEvent> replaces AnyEvent's condvars by coroutine-safe
610	versions and also integrates coroutines into AnyEvent, making blocking
611	C<< ->recv >> calls perfectly safe as long as they are done from another
612	coroutine (one that doesn't run the event loop).
613
614	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
615	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
616	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
617	waits otherwise.	783	waits otherwise.
618		784
…		…
624	=item $cb = $cv->cb ($cb->($cv))	790	=item $cb = $cv->cb ($cb->($cv))
625		791
626	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
627	replaces it before doing so.	793	replaces it before doing so.
628		794
629	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)
630	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
631	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>
632	is guaranteed not to block.	798	inside the callback or at any later time is guaranteed not to block.
633		799
634	=back	800	=back
635		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
636	=head1 GLOBAL VARIABLES AND FUNCTIONS	870	=head1 GLOBAL VARIABLES AND FUNCTIONS
637		871
		872	These are not normally required to use AnyEvent, but can be useful to
		873	write AnyEvent extension modules.
		874
638	=over 4	875	=over 4
639		876
640	=item $AnyEvent::MODEL	877	=item $AnyEvent::MODEL
641		878
642	Contains C<undef> until the first watcher is being created. Then it	879	Contains C<undef> until the first watcher is being created, before the
		880	backend has been autodetected.
		881
643	contains the event model that is being used, which is the name of the	882	Afterwards it contains the event model that is being used, which is the
644	Perl class implementing the model. This class is usually one of the	883	name of the Perl class implementing the model. This class is usually one
645	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	884	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
646	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	885	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
647		886	will be C<urxvt::anyevent>).
648	The known classes so far are:
649
650	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
651	AnyEvent::Impl::Event based on Event, second best choice.
652	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
653	AnyEvent::Impl::Glib based on Glib, third-best choice.
654	AnyEvent::Impl::Tk based on Tk, very bad choice.
655	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
656	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
657	AnyEvent::Impl::POE based on POE, not generic enough for full support.
658
659	There is no support for WxWidgets, as WxWidgets has no support for
660	watching file handles. However, you can use WxWidgets through the
661	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
662	second, which was considered to be too horrible to even consider for
663	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
664	it's adaptor.
665
666	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
667	autodetecting them.
668		887
669	=item AnyEvent::detect	888	=item AnyEvent::detect
670		889
671	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	890	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
672	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
673	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
674	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>.
675		897
676	=item $guard = AnyEvent::post_detect { BLOCK }	898	=item $guard = AnyEvent::post_detect { BLOCK }
677		899
678	Arranges for the code block to be executed as soon as the event model is	900	Arranges for the code block to be executed as soon as the event model is
679	autodetected (or immediately if this has already happened).	901	autodetected (or immediately if this has already happened).
680		902
		903	The block will be executed I<after> the actual backend has been detected
		904	(C<$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
681	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
682	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
683	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 ||= $guard;
684		934
685	=item @AnyEvent::post_detect	935	=item @AnyEvent::post_detect
686		936
687	If there are any code references in this array (you can C<push> to it	937	If there are any code references in this array (you can C<push> to it
688	before or after loading AnyEvent), then they will called directly after	938	before or after loading AnyEvent), then they will called directly after
689	the event loop has been chosen.	939	the event loop has been chosen.
690		940
691	You should check C<$AnyEvent::MODEL> before adding to this array, though:	941	You should check C<$AnyEvent::MODEL> before adding to this array, though:
692	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
693	and the array will be ignored.	943	array will be ignored.
694		944
695	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.
696		952
697	=back	953	=back
698		954
699	=head1 WHAT TO DO IN A MODULE	955	=head1 WHAT TO DO IN A MODULE
700		956
…		…
755		1011
756		1012
757	=head1 OTHER MODULES	1013	=head1 OTHER MODULES
758		1014
759	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
760	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
761	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
762	available via CPAN.	1018	come with AnyEvent, most are available via CPAN.
763		1019
764	=over 4	1020	=over 4
765		1021
766	=item L<AnyEvent::Util>	1022	=item L<AnyEvent::Util>
767		1023
…		…
776		1032
777	=item L<AnyEvent::Handle>	1033	=item L<AnyEvent::Handle>
778		1034
779	Provide read and write buffers, manages watchers for reads and writes,	1035	Provide read and write buffers, manages watchers for reads and writes,
780	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
781	non-blocking SSL/TLS.	1037	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
782		1038
783	=item L<AnyEvent::DNS>	1039	=item L<AnyEvent::DNS>
784		1040
785	Provides rich asynchronous DNS resolver capabilities.	1041	Provides rich asynchronous DNS resolver capabilities.
786		1042
…		…
814		1070
815	=item L<AnyEvent::GPSD>	1071	=item L<AnyEvent::GPSD>
816		1072
817	A non-blocking interface to gpsd, a daemon delivering GPS information.	1073	A non-blocking interface to gpsd, a daemon delivering GPS information.
818		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
819	=item L<AnyEvent::IGS>	1084	=item L<AnyEvent::IGS>
820		1085
821	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
822	L<App::IGS>).	1087	L<App::IGS>).
823		1088
824	=item L<Net::IRC3>
825
826	AnyEvent based IRC client module family.
827
828	=item L<Net::XMPP2>
829
830	AnyEvent based XMPP (Jabber protocol) module family.
831
832	=item L<Net::FCP>	1089	=item L<Net::FCP>
833		1090
834	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1091	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
835	of AnyEvent.	1092	of AnyEvent.
836		1093
…		…
840		1097
841	=item L<Coro>	1098	=item L<Coro>
842		1099
843	Has special support for AnyEvent via L<Coro::AnyEvent>.	1100	Has special support for AnyEvent via L<Coro::AnyEvent>.
844		1101
845	=item L<IO::Lambda>
846
847	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
848
849	=back	1102	=back
850		1103
851	=cut	1104	=cut
852		1105
853	package AnyEvent;	1106	package AnyEvent;
854		1107
		1108	# basically a tuned-down version of common::sense
		1109	sub common_sense {
855	no warnings;	1110	# no warnings
856	use strict;	1111	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1112	# use strict vars subs
		1113	$^H |= 0x00000600;
		1114	}
857		1115
		1116	BEGIN { AnyEvent::common_sense }
		1117
858	use Carp;	1118	use Carp ();
859		1119
860	our $VERSION = 4.22;	1120	our $VERSION = '5.0';
861	our $MODEL;	1121	our $MODEL;
862		1122
863	our $AUTOLOAD;	1123	our $AUTOLOAD;
864	our @ISA;	1124	our @ISA;
865		1125
866	our @REGISTRY;	1126	our @REGISTRY;
867		1127
868	our $WIN32;	1128	our $WIN32;
869		1129
		1130	our $VERBOSE;
		1131
870	BEGIN {	1132	BEGIN {
871	my $win32 = ! ! ($^O =~ /mswin32/i);	1133	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
872	eval "sub WIN32(){ $win32 }";	1134	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
873	}
874		1135
		1136	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1137	if ${^TAINT};
		1138
875	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1139	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1140
		1141	}
		1142
		1143	our $MAX_SIGNAL_LATENCY = 10;
876		1144
877	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1145	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
878		1146
879	{	1147	{
880	my $idx;	1148	my $idx;
…		…
882	for reverse split /\s*,\s*/,	1150	for reverse split /\s*,\s*/,
883	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";	1151	$ENV{PERL_ANYEVENT_PROTOCOLS} || "ipv4,ipv6";
884	}	1152	}
885		1153
886	my @models = (	1154	my @models = (
887	[EV:: => AnyEvent::Impl::EV::],	1155	[EV:: => AnyEvent::Impl::EV:: , 1],
888	[Event:: => AnyEvent::Impl::Event::],
889	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1156	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl:: , 1],
890	# everything below here will not be autoprobed	1157	# everything below here will not (normally) be autoprobed
891	# as the pureperl backend should work everywhere	1158	# as the pureperl backend should work everywhere
892	# 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
893	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles	1164	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
894	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
895	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
896	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1165	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
897	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1166	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
898	[Wx:: => AnyEvent::Impl::POE::],	1167	[Wx:: => AnyEvent::Impl::POE::],
899	[Prima:: => AnyEvent::Impl::POE::],	1168	[Prima:: => AnyEvent::Impl::POE::],
		1169	# IO::Async is just too broken - we would need workarounds for its
		1170	# byzantine signal and broken child handling, among others.
		1171	# IO::Async is rather hard to detect, as it doesn't have any
		1172	# obvious default class.
		1173	[IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1174	[IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1175	[IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1176	[AnyEvent::Impl::IOAsync:: => AnyEvent::Impl::IOAsync::], # requires special main program
900	);	1177	);
901		1178
902	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1179	our %method = map +($_ => 1),
		1180	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
903		1181
904	our @post_detect;	1182	our @post_detect;
905		1183
906	sub post_detect(&) {	1184	sub post_detect(&) {
907	my ($cb) = @_;	1185	my ($cb) = @_;
908		1186
909	if ($MODEL) {	1187	if ($MODEL) {
910	$cb->();	1188	$cb->();
911		1189
912	1	1190	undef
913	} else {	1191	} else {
914	push @post_detect, $cb;	1192	push @post_detect, $cb;
915		1193
916	defined wantarray	1194	defined wantarray
917	? bless \$cb, "AnyEvent::Util::PostDetect"	1195	? bless \$cb, "AnyEvent::Util::postdetect"
918	: ()	1196	: ()
919	}	1197	}
920	}	1198	}
921		1199
922	sub AnyEvent::Util::PostDetect::DESTROY {	1200	sub AnyEvent::Util::postdetect::DESTROY {
923	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1201	@post_detect = grep $_ != ${$_[0]}, @post_detect;
924	}	1202	}
925		1203
926	sub detect() {	1204	sub detect() {
927	unless ($MODEL) {	1205	unless ($MODEL) {
928	no strict 'refs';
929	local $SIG{__DIE__};	1206	local $SIG{__DIE__};
930		1207
931	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1208	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
932	my $model = "AnyEvent::Impl::$1";	1209	my $model = "AnyEvent::Impl::$1";
933	if (eval "require $model") {	1210	if (eval "require $model") {
934	$MODEL = $model;	1211	$MODEL = $model;
935	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1212	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
936	} else {	1213	} else {
937	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1214	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
938	}	1215	}
939	}	1216	}
940		1217
941	# check for already loaded models	1218	# check for already loaded models
942	unless ($MODEL) {	1219	unless ($MODEL) {
943	for (@REGISTRY, @models) {	1220	for (@REGISTRY, @models) {
944	my ($package, $model) = @$_;	1221	my ($package, $model) = @$_;
945	if (${"$package\::VERSION"} > 0) {	1222	if (${"$package\::VERSION"} > 0) {
946	if (eval "require $model") {	1223	if (eval "require $model") {
947	$MODEL = $model;	1224	$MODEL = $model;
948	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1225	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
949	last;	1226	last;
950	}	1227	}
951	}	1228	}
952	}	1229	}
953		1230
954	unless ($MODEL) {	1231	unless ($MODEL) {
955	# try to load a model	1232	# try to autoload a model
956
957	for (@REGISTRY, @models) {	1233	for (@REGISTRY, @models) {
958	my ($package, $model) = @$_;	1234	my ($package, $model, $autoload) = @$_;
		1235	if (
		1236	$autoload
959	if (eval "require $package"	1237	and eval "require $package"
960	and ${"$package\::VERSION"} > 0	1238	and ${"$package\::VERSION"} > 0
961	and eval "require $model") {	1239	and eval "require $model"
		1240	) {
962	$MODEL = $model;	1241	$MODEL = $model;
963	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1242	warn "AnyEvent: autoloaded model '$model', using it.\n" if $VERBOSE >= 2;
964	last;	1243	last;
965	}	1244	}
966	}	1245	}
967		1246
968	$MODEL	1247	$MODEL
969	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1248	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
970	}	1249	}
971	}	1250	}
972		1251
973	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1252	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
974		1253
…		…
984		1263
985	sub AUTOLOAD {	1264	sub AUTOLOAD {
986	(my $func = $AUTOLOAD) =~ s/.*://;	1265	(my $func = $AUTOLOAD) =~ s/.*://;
987		1266
988	$method{$func}	1267	$method{$func}
989	or croak "$func: not a valid method for AnyEvent objects";	1268	or Carp::croak "$func: not a valid method for AnyEvent objects";
990		1269
991	detect unless $MODEL;	1270	detect unless $MODEL;
992		1271
993	my $class = shift;	1272	my $class = shift;
994	$class->$func (@_);	1273	$class->$func (@_);
995	}	1274	}
996		1275
997	# utility function to dup a filehandle. this is used by many backends	1276	# utility function to dup a filehandle. this is used by many backends
998	# to support binding more than one watcher per filehandle (they usually	1277	# to support binding more than one watcher per filehandle (they usually
999	# allow only one watcher per fd, so we dup it to get a different one).	1278	# allow only one watcher per fd, so we dup it to get a different one).
1000	sub _dupfh($$$$) {	1279	sub _dupfh($$;$$) {
1001	my ($poll, $fh, $r, $w) = @_;	1280	my ($poll, $fh, $r, $w) = @_;
1002		1281
1003	require Fcntl;
1004
1005	# cygwin requires the fh mode to be matching, unix doesn't	1282	# cygwin requires the fh mode to be matching, unix doesn't
1006	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1283	my ($rw, $mode) = $poll eq "r" ? ($r, "<&") : ($w, ">&");
1007	: $poll eq "w" ? ($w, ">")
1008	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
1009		1284
1010	open my $fh2, "$mode&" . fileno $fh	1285	open my $fh2, $mode, $fh
1011	or die "cannot dup() filehandle: $!";	1286	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1012		1287
1013	# we assume CLOEXEC is already set by perl in all important cases	1288	# we assume CLOEXEC is already set by perl in all important cases
1014		1289
1015	($fh2, $rw)	1290	($fh2, $rw)
1016	}	1291	}
1017		1292
		1293	=head1 SIMPLIFIED AE API
		1294
		1295	Starting with version 5.0, AnyEvent officially supports a second, much
		1296	simpler, API that is designed to reduce the calling, typing and memory
		1297	overhead.
		1298
		1299	See the L<AE> manpage for details.
		1300
		1301	=cut
		1302
		1303	package AE;
		1304
		1305	our $VERSION = $AnyEvent::VERSION;
		1306
		1307	sub io($$$) {
		1308	AnyEvent->io (fh => $_[0], poll => $_[1] ? "w" : "r", cb => $_[2])
		1309	}
		1310
		1311	sub timer($$$) {
		1312	AnyEvent->timer (after => $_[0], interval => $_[1], cb => $_[2])
		1313	}
		1314
		1315	sub signal($$) {
		1316	AnyEvent->signal (signal => $_[0], cb => $_[1])
		1317	}
		1318
		1319	sub child($$) {
		1320	AnyEvent->child (pid => $_[0], cb => $_[1])
		1321	}
		1322
		1323	sub idle($) {
		1324	AnyEvent->idle (cb => $_[0])
		1325	}
		1326
		1327	sub cv(;&) {
		1328	AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
		1329	}
		1330
		1331	sub now() {
		1332	AnyEvent->now
		1333	}
		1334
		1335	sub now_update() {
		1336	AnyEvent->now_update
		1337	}
		1338
		1339	sub time() {
		1340	AnyEvent->time
		1341	}
		1342
1018	package AnyEvent::Base;	1343	package AnyEvent::Base;
1019		1344
1020	# default implementation for now and time	1345	# default implementations for many methods
1021		1346
1022	use Time::HiRes ();	1347	sub _time {
		1348	# probe for availability of Time::HiRes
		1349	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1350	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1351	*_time = \&Time::HiRes::time;
		1352	# if (eval "use POSIX (); (POSIX::times())...
		1353	} else {
		1354	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1355	*_time = sub { time }; # epic fail
		1356	}
1023		1357
1024	sub time { Time::HiRes::time }	1358	&_time
1025	sub now { Time::HiRes::time }	1359	}
		1360
		1361	sub time { _time }
		1362	sub now { _time }
		1363	sub now_update { }
1026		1364
1027	# default implementation for ->condvar	1365	# default implementation for ->condvar
1028		1366
1029	sub condvar {	1367	sub condvar {
1030	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1368	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1031	}	1369	}
1032		1370
1033	# default implementation for ->signal	1371	# default implementation for ->signal
1034		1372
1035	our %SIG_CB;	1373	our $HAVE_ASYNC_INTERRUPT;
		1374
		1375	sub _have_async_interrupt() {
		1376	$HAVE_ASYNC_INTERRUPT = 1*(!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT}
		1377	&& eval "use Async::Interrupt 1.0 (); 1")
		1378	unless defined $HAVE_ASYNC_INTERRUPT;
		1379
		1380	$HAVE_ASYNC_INTERRUPT
		1381	}
		1382
		1383	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1384	our (%SIG_ASY, %SIG_ASY_W);
		1385	our ($SIG_COUNT, $SIG_TW);
		1386
		1387	sub _signal_exec {
		1388	$HAVE_ASYNC_INTERRUPT
		1389	? $SIGPIPE_R->drain
		1390	: sysread $SIGPIPE_R, my $dummy, 9;
		1391
		1392	while (%SIG_EV) {
		1393	for (keys %SIG_EV) {
		1394	delete $SIG_EV{$_};
		1395	$_->() for values %{ $SIG_CB{$_} || {} };
		1396	}
		1397	}
		1398	}
		1399
		1400	# install a dummy wakeup watcher to reduce signal catching latency
		1401	sub _sig_add() {
		1402	unless ($SIG_COUNT++) {
		1403	# try to align timer on a full-second boundary, if possible
		1404	my $NOW = AE::now;
		1405
		1406	$SIG_TW = AE::timer
		1407	$MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1408	$MAX_SIGNAL_LATENCY,
		1409	sub { } # just for the PERL_ASYNC_CHECK
		1410	;
		1411	}
		1412	}
		1413
		1414	sub _sig_del {
		1415	undef $SIG_TW
		1416	unless --$SIG_COUNT;
		1417	}
		1418
		1419	our $_sig_name_init; $_sig_name_init = sub {
		1420	eval q{ # poor man's autoloading
		1421	undef $_sig_name_init;
		1422
		1423	if (_have_async_interrupt) {
		1424	*sig2num = \&Async::Interrupt::sig2num;
		1425	*sig2name = \&Async::Interrupt::sig2name;
		1426	} else {
		1427	require Config;
		1428
		1429	my %signame2num;
		1430	@signame2num{ split ' ', $Config::Config{sig_name} }
		1431	= split ' ', $Config::Config{sig_num};
		1432
		1433	my @signum2name;
		1434	@signum2name[values %signame2num] = keys %signame2num;
		1435
		1436	*sig2num = sub($) {
		1437	$_[0] > 0 ? shift : $signame2num{+shift}
		1438	};
		1439	*sig2name = sub ($) {
		1440	$_[0] > 0 ? $signum2name[+shift] : shift
		1441	};
		1442	}
		1443	};
		1444	die if $@;
		1445	};
		1446
		1447	sub sig2num ($) { &$_sig_name_init; &sig2num }
		1448	sub sig2name($) { &$_sig_name_init; &sig2name }
1036		1449
1037	sub signal {	1450	sub signal {
		1451	eval q{ # poor man's autoloading {}
		1452	# probe for availability of Async::Interrupt
		1453	if (_have_async_interrupt) {
		1454	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1455
		1456	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1457	$SIG_IO = AE::io $SIGPIPE_R->fileno, 0, \&_signal_exec;
		1458
		1459	} else {
		1460	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1461
		1462	require Fcntl;
		1463
		1464	if (AnyEvent::WIN32) {
		1465	require AnyEvent::Util;
		1466
		1467	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1468	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R, 1) if $SIGPIPE_R;
		1469	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W, 1) if $SIGPIPE_W; # just in case
		1470	} else {
		1471	pipe $SIGPIPE_R, $SIGPIPE_W;
		1472	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1473	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1474
		1475	# not strictly required, as $^F is normally 2, but let's make sure...
		1476	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1477	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1478	}
		1479
		1480	$SIGPIPE_R
		1481	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1482
		1483	$SIG_IO = AE::io $SIGPIPE_R, 0, \&_signal_exec;
		1484	}
		1485
		1486	*signal = sub {
1038	my (undef, %arg) = @_;	1487	my (undef, %arg) = @_;
1039		1488
1040	my $signal = uc $arg{signal}	1489	my $signal = uc $arg{signal}
1041	or Carp::croak "required option 'signal' is missing";	1490	or Carp::croak "required option 'signal' is missing";
1042		1491
		1492	if ($HAVE_ASYNC_INTERRUPT) {
		1493	# async::interrupt
		1494
		1495	$signal = sig2num $signal;
1043	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1496	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1497
		1498	$SIG_ASY{$signal} ||= new Async::Interrupt
		1499	cb => sub { undef $SIG_EV{$signal} },
		1500	signal => $signal,
		1501	pipe => [$SIGPIPE_R->filenos],
		1502	pipe_autodrain => 0,
		1503	;
		1504
		1505	} else {
		1506	# pure perl
		1507
		1508	# AE::Util has been loaded in signal
		1509	$signal = sig2name $signal;
		1510	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1511
1044	$SIG{$signal} ||= sub {	1512	$SIG{$signal} ||= sub {
1045	$_->() for values %{ $SIG_CB{$signal} || {} };	1513	local $!;
		1514	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1515	undef $SIG_EV{$signal};
		1516	};
		1517
		1518	# can't do signal processing without introducing races in pure perl,
		1519	# so limit the signal latency.
		1520	_sig_add;
		1521	}
		1522
		1523	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
		1524	};
		1525
		1526	*AnyEvent::Base::signal::DESTROY = sub {
		1527	my ($signal, $cb) = @{$_[0]};
		1528
		1529	_sig_del;
		1530
		1531	delete $SIG_CB{$signal}{$cb};
		1532
		1533	$HAVE_ASYNC_INTERRUPT
		1534	? delete $SIG_ASY{$signal}
		1535	: # delete doesn't work with older perls - they then
		1536	# print weird messages, or just unconditionally exit
		1537	# instead of getting the default action.
		1538	undef $SIG{$signal}
		1539	unless keys %{ $SIG_CB{$signal} };
		1540	};
1046	};	1541	};
1047		1542	die if $@;
1048	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1543	&signal
1049	}
1050
1051	sub AnyEvent::Base::Signal::DESTROY {
1052	my ($signal, $cb) = @{$_[0]};
1053
1054	delete $SIG_CB{$signal}{$cb};
1055
1056	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1057	}	1544	}
1058		1545
1059	# default implementation for ->child	1546	# default implementation for ->child
1060		1547
1061	our %PID_CB;	1548	our %PID_CB;
1062	our $CHLD_W;	1549	our $CHLD_W;
1063	our $CHLD_DELAY_W;	1550	our $CHLD_DELAY_W;
1064	our $PID_IDLE;
1065	our $WNOHANG;	1551	our $WNOHANG;
1066		1552
1067	sub _child_wait {	1553	sub _emit_childstatus($$) {
1068	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1554	my (undef, $rpid, $rstatus) = @_;
		1555
		1556	$_->($rpid, $rstatus)
1069	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1557	for values %{ $PID_CB{$rpid} || {} },
1070	(values %{ $PID_CB{0} || {} });	1558	values %{ $PID_CB{0} || {} };
1071	}
1072
1073	undef $PID_IDLE;
1074	}	1559	}
1075		1560
1076	sub _sigchld {	1561	sub _sigchld {
1077	# make sure we deliver these changes "synchronous" with the event loop.	1562	my $pid;
1078	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {	1563
1079	undef $CHLD_DELAY_W;	1564	AnyEvent->_emit_childstatus ($pid, $?)
1080	&_child_wait;	1565	while ($pid = waitpid -1, $WNOHANG) > 0;
1081	});
1082	}	1566	}
1083		1567
1084	sub child {	1568	sub child {
1085	my (undef, %arg) = @_;	1569	my (undef, %arg) = @_;
1086		1570
1087	defined (my $pid = $arg{pid} + 0)	1571	defined (my $pid = $arg{pid} + 0)
1088	or Carp::croak "required option 'pid' is missing";	1572	or Carp::croak "required option 'pid' is missing";
1089		1573
1090	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1574	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1091		1575
1092	unless ($WNOHANG) {	1576	# WNOHANG is almost cetrainly 1 everywhere
		1577	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1578	? 1
1093	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1579	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1094	}
1095		1580
1096	unless ($CHLD_W) {	1581	unless ($CHLD_W) {
1097	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1582	$CHLD_W = AE::signal CHLD => \&_sigchld;
1098	# child could be a zombie already, so make at least one round	1583	# child could be a zombie already, so make at least one round
1099	&_sigchld;	1584	&_sigchld;
1100	}	1585	}
1101		1586
1102	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1587	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1103	}	1588	}
1104		1589
1105	sub AnyEvent::Base::Child::DESTROY {	1590	sub AnyEvent::Base::child::DESTROY {
1106	my ($pid, $cb) = @{$_[0]};	1591	my ($pid, $cb) = @{$_[0]};
1107		1592
1108	delete $PID_CB{$pid}{$cb};	1593	delete $PID_CB{$pid}{$cb};
1109	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1594	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1110		1595
1111	undef $CHLD_W unless keys %PID_CB;	1596	undef $CHLD_W unless keys %PID_CB;
1112	}	1597	}
1113		1598
		1599	# idle emulation is done by simply using a timer, regardless
		1600	# of whether the process is idle or not, and not letting
		1601	# the callback use more than 50% of the time.
		1602	sub idle {
		1603	my (undef, %arg) = @_;
		1604
		1605	my ($cb, $w, $rcb) = $arg{cb};
		1606
		1607	$rcb = sub {
		1608	if ($cb) {
		1609	$w = _time;
		1610	&$cb;
		1611	$w = _time - $w;
		1612
		1613	# never use more then 50% of the time for the idle watcher,
		1614	# within some limits
		1615	$w = 0.0001 if $w < 0.0001;
		1616	$w = 5 if $w > 5;
		1617
		1618	$w = AE::timer $w, 0, $rcb;
		1619	} else {
		1620	# clean up...
		1621	undef $w;
		1622	undef $rcb;
		1623	}
		1624	};
		1625
		1626	$w = AE::timer 0.05, 0, $rcb;
		1627
		1628	bless \\$cb, "AnyEvent::Base::idle"
		1629	}
		1630
		1631	sub AnyEvent::Base::idle::DESTROY {
		1632	undef $${$_[0]};
		1633	}
		1634
1114	package AnyEvent::CondVar;	1635	package AnyEvent::CondVar;
1115		1636
1116	our @ISA = AnyEvent::CondVar::Base::;	1637	our @ISA = AnyEvent::CondVar::Base::;
1117		1638
1118	package AnyEvent::CondVar::Base;	1639	package AnyEvent::CondVar::Base;
1119		1640
1120	use overload	1641	#use overload
1121	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1642	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1122	fallback => 1;	1643	# fallback => 1;
		1644
		1645	# save 300+ kilobytes by dirtily hardcoding overloading
		1646	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1647	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1648	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1649	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1650
		1651	our $WAITING;
1123		1652
1124	sub _send {	1653	sub _send {
1125	# nop	1654	# nop
1126	}	1655	}
1127		1656
…		…
1140	sub ready {	1669	sub ready {
1141	$_[0]{_ae_sent}	1670	$_[0]{_ae_sent}
1142	}	1671	}
1143		1672
1144	sub _wait {	1673	sub _wait {
		1674	$WAITING
		1675	and !$_[0]{_ae_sent}
		1676	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1677
		1678	local $WAITING = 1;
1145	AnyEvent->one_event while !$_[0]{_ae_sent};	1679	AnyEvent->one_event while !$_[0]{_ae_sent};
1146	}	1680	}
1147		1681
1148	sub recv {	1682	sub recv {
1149	$_[0]->_wait;	1683	$_[0]->_wait;
…		…
1151	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};	1685	Carp::croak $_[0]{_ae_croak} if $_[0]{_ae_croak};
1152	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]	1686	wantarray ? @{ $_[0]{_ae_sent} } : $_[0]{_ae_sent}[0]
1153	}	1687	}
1154		1688
1155	sub cb {	1689	sub cb {
1156	$_[0]{_ae_cb} = $_[1] if @_ > 1;	1690	my $cv = shift;
		1691
		1692	@_
		1693	and $cv->{_ae_cb} = shift
		1694	and $cv->{_ae_sent}
		1695	and (delete $cv->{_ae_cb})->($cv);
		1696
1157	$_[0]{_ae_cb}	1697	$cv->{_ae_cb}
1158	}	1698	}
1159		1699
1160	sub begin {	1700	sub begin {
1161	++$_[0]{_ae_counter};	1701	++$_[0]{_ae_counter};
1162	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;	1702	$_[0]{_ae_end_cb} = $_[1] if @_ > 1;
…		…
1168	}	1708	}
1169		1709
1170	# undocumented/compatibility with pre-3.4	1710	# undocumented/compatibility with pre-3.4
1171	*broadcast = \&send;	1711	*broadcast = \&send;
1172	*wait = \&_wait;	1712	*wait = \&_wait;
		1713
		1714	=head1 ERROR AND EXCEPTION HANDLING
		1715
		1716	In general, AnyEvent does not do any error handling - it relies on the
		1717	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1718	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1719	checking of all AnyEvent methods, however, which is highly useful during
		1720	development.
		1721
		1722	As for exception handling (i.e. runtime errors and exceptions thrown while
		1723	executing a callback), this is not only highly event-loop specific, but
		1724	also not in any way wrapped by this module, as this is the job of the main
		1725	program.
		1726
		1727	The pure perl event loop simply re-throws the exception (usually
		1728	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1729	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1730	so on.
		1731
		1732	=head1 ENVIRONMENT VARIABLES
		1733
		1734	The following environment variables are used by this module or its
		1735	submodules.
		1736
		1737	Note that AnyEvent will remove I<all> environment variables starting with
		1738	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1739	enabled.
		1740
		1741	=over 4
		1742
		1743	=item C<PERL_ANYEVENT_VERBOSE>
		1744
		1745	By default, AnyEvent will be completely silent except in fatal
		1746	conditions. You can set this environment variable to make AnyEvent more
		1747	talkative.
		1748
		1749	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1750	conditions, such as not being able to load the event model specified by
		1751	C<PERL_ANYEVENT_MODEL>.
		1752
		1753	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1754	model it chooses.
		1755
		1756	When set to C<8> or higher, then AnyEvent will report extra information on
		1757	which optional modules it loads and how it implements certain features.
		1758
		1759	=item C<PERL_ANYEVENT_STRICT>
		1760
		1761	AnyEvent does not do much argument checking by default, as thorough
		1762	argument checking is very costly. Setting this variable to a true value
		1763	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1764	check the arguments passed to most method calls. If it finds any problems,
		1765	it will croak.
		1766
		1767	In other words, enables "strict" mode.
		1768
		1769	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1770	>>, it is definitely recommended to keep it off in production. Keeping
		1771	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1772	can be very useful, however.
		1773
		1774	=item C<PERL_ANYEVENT_MODEL>
		1775
		1776	This can be used to specify the event model to be used by AnyEvent, before
		1777	auto detection and -probing kicks in. It must be a string consisting
		1778	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1779	and the resulting module name is loaded and if the load was successful,
		1780	used as event model. If it fails to load AnyEvent will proceed with
		1781	auto detection and -probing.
		1782
		1783	This functionality might change in future versions.
		1784
		1785	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1786	could start your program like this:
		1787
		1788	PERL_ANYEVENT_MODEL=Perl perl ...
		1789
		1790	=item C<PERL_ANYEVENT_PROTOCOLS>
		1791
		1792	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1793	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1794	of auto probing).
		1795
		1796	Must be set to a comma-separated list of protocols or address families,
		1797	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1798	used, and preference will be given to protocols mentioned earlier in the
		1799	list.
		1800
		1801	This variable can effectively be used for denial-of-service attacks
		1802	against local programs (e.g. when setuid), although the impact is likely
		1803	small, as the program has to handle conenction and other failures anyways.
		1804
		1805	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1806	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1807	- only support IPv4, never try to resolve or contact IPv6
		1808	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1809	IPv6, but prefer IPv6 over IPv4.
		1810
		1811	=item C<PERL_ANYEVENT_EDNS0>
		1812
		1813	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1814	for DNS. This extension is generally useful to reduce DNS traffic, but
		1815	some (broken) firewalls drop such DNS packets, which is why it is off by
		1816	default.
		1817
		1818	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1819	EDNS0 in its DNS requests.
		1820
		1821	=item C<PERL_ANYEVENT_MAX_FORKS>
		1822
		1823	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1824	will create in parallel.
		1825
		1826	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1827
		1828	The default value for the C<max_outstanding> parameter for the default DNS
		1829	resolver - this is the maximum number of parallel DNS requests that are
		1830	sent to the DNS server.
		1831
		1832	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1833
		1834	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1835	configuration) in the default resolver. When set to the empty string, no
		1836	default config will be used.
		1837
		1838	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1839
		1840	When neither C<ca_file> nor C<ca_path> was specified during
		1841	L<AnyEvent::TLS> context creation, and either of these environment
		1842	variables exist, they will be used to specify CA certificate locations
		1843	instead of a system-dependent default.
		1844
		1845	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1846
		1847	When these are set to C<1>, then the respective modules are not
		1848	loaded. Mostly good for testing AnyEvent itself.
		1849
		1850	=back
1173		1851
1174	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1852	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1175		1853
1176	This is an advanced topic that you do not normally need to use AnyEvent in	1854	This is an advanced topic that you do not normally need to use AnyEvent in
1177	a module. This section is only of use to event loop authors who want to	1855	a module. This section is only of use to event loop authors who want to
…		…
1211		1889
1212	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1890	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1213	condition variables: code blocking while waiting for a condition will	1891	condition variables: code blocking while waiting for a condition will
1214	C<die>. This still works with most modules/usages, and blocking calls must	1892	C<die>. This still works with most modules/usages, and blocking calls must
1215	not be done in an interactive application, so it makes sense.	1893	not be done in an interactive application, so it makes sense.
1216
1217	=head1 ENVIRONMENT VARIABLES
1218
1219	The following environment variables are used by this module:
1220
1221	=over 4
1222
1223	=item C<PERL_ANYEVENT_VERBOSE>
1224
1225	By default, AnyEvent will be completely silent except in fatal
1226	conditions. You can set this environment variable to make AnyEvent more
1227	talkative.
1228
1229	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1230	conditions, such as not being able to load the event model specified by
1231	C<PERL_ANYEVENT_MODEL>.
1232
1233	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1234	model it chooses.
1235
1236	=item C<PERL_ANYEVENT_STRICT>
1237
1238	AnyEvent does not do much argument checking by default, as thorough
1239	argument checking is very costly. Setting this variable to a true value
1240	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
1241	check the arguments passed to most method calls. If it finds any problems
1242	it will croak.
1243
1244	In other words, enables "strict" mode.
1245
1246	Unlike C<use strict> it is definitely recommended ot keep it off in
1247	production.
1248
1249	=item C<PERL_ANYEVENT_MODEL>
1250
1251	This can be used to specify the event model to be used by AnyEvent, before
1252	auto detection and -probing kicks in. It must be a string consisting
1253	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1254	and the resulting module name is loaded and if the load was successful,
1255	used as event model. If it fails to load AnyEvent will proceed with
1256	auto detection and -probing.
1257
1258	This functionality might change in future versions.
1259
1260	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1261	could start your program like this:
1262
1263	PERL_ANYEVENT_MODEL=Perl perl ...
1264
1265	=item C<PERL_ANYEVENT_PROTOCOLS>
1266
1267	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1268	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1269	of auto probing).
1270
1271	Must be set to a comma-separated list of protocols or address families,
1272	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1273	used, and preference will be given to protocols mentioned earlier in the
1274	list.
1275
1276	This variable can effectively be used for denial-of-service attacks
1277	against local programs (e.g. when setuid), although the impact is likely
1278	small, as the program has to handle connection errors already-
1279
1280	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1281	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1282	- only support IPv4, never try to resolve or contact IPv6
1283	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1284	IPv6, but prefer IPv6 over IPv4.
1285
1286	=item C<PERL_ANYEVENT_EDNS0>
1287
1288	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1289	for DNS. This extension is generally useful to reduce DNS traffic, but
1290	some (broken) firewalls drop such DNS packets, which is why it is off by
1291	default.
1292
1293	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1294	EDNS0 in its DNS requests.
1295
1296	=item C<PERL_ANYEVENT_MAX_FORKS>
1297
1298	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1299	will create in parallel.
1300
1301	=back
1302		1894
1303	=head1 EXAMPLE PROGRAM	1895	=head1 EXAMPLE PROGRAM
1304		1896
1305	The following program uses an I/O watcher to read data from STDIN, a timer	1897	The following program uses an I/O watcher to read data from STDIN, a timer
1306	to display a message once per second, and a condition variable to quit the	1898	to display a message once per second, and a condition variable to quit the
…		…
1469	through AnyEvent. The benchmark creates a lot of timers (with a zero	2061	through AnyEvent. The benchmark creates a lot of timers (with a zero
1470	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,	2062	timeout) and I/O watchers (watching STDOUT, a pty, to become writable,
1471	which it is), lets them fire exactly once and destroys them again.	2063	which it is), lets them fire exactly once and destroys them again.
1472		2064
1473	Source code for this benchmark is found as F<eg/bench> in the AnyEvent	2065	Source code for this benchmark is found as F<eg/bench> in the AnyEvent
1474	distribution.	2066	distribution. It uses the L<AE> interface, which makes a real difference
		2067	for the EV and Perl backends only.
1475		2068
1476	=head3 Explanation of the columns	2069	=head3 Explanation of the columns
1477		2070
1478	I<watcher> is the number of event watchers created/destroyed. Since	2071	I<watcher> is the number of event watchers created/destroyed. Since
1479	different event models feature vastly different performances, each event	2072	different event models feature vastly different performances, each event
…		…
1500	watcher.	2093	watcher.
1501		2094
1502	=head3 Results	2095	=head3 Results
1503		2096
1504	name watchers bytes create invoke destroy comment	2097	name watchers bytes create invoke destroy comment
1505	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	2098	EV/EV 100000 223 0.47 0.43 0.27 EV native interface
1506	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	2099	EV/Any 100000 223 0.48 0.42 0.26 EV + AnyEvent watchers
1507	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	2100	Coro::EV/Any 100000 223 0.47 0.42 0.26 coroutines + Coro::Signal
1508	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	2101	Perl/Any 100000 431 2.70 0.74 0.92 pure perl implementation
1509	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	2102	Event/Event 16000 516 31.16 31.84 0.82 Event native interface
1510	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	2103	Event/Any 16000 1203 42.61 34.79 1.80 Event + AnyEvent watchers
		2104	IOAsync/Any 16000 1911 41.92 27.45 16.81 via IO::Async::Loop::IO_Poll
		2105	IOAsync/Any 16000 1726 40.69 26.37 15.25 via IO::Async::Loop::Epoll
1511	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	2106	Glib/Any 16000 1118 89.00 12.57 51.17 quadratic behaviour
1512	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	2107	Tk/Any 2000 1346 20.96 10.75 8.00 SEGV with >> 2000 watchers
1513	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	2108	POE/Any 2000 6951 108.97 795.32 14.24 via POE::Loop::Event
1514	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	2109	POE/Any 2000 6648 94.79 774.40 575.51 via POE::Loop::Select
1515		2110
1516	=head3 Discussion	2111	=head3 Discussion
1517		2112
1518	The benchmark does I<not> measure scalability of the event loop very	2113	The benchmark does I<not> measure scalability of the event loop very
1519	well. For example, a select-based event loop (such as the pure perl one)	2114	well. For example, a select-based event loop (such as the pure perl one)
…		…
1531	benchmark machine, handling an event takes roughly 1600 CPU cycles with	2126	benchmark machine, handling an event takes roughly 1600 CPU cycles with
1532	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU	2127	EV, 3100 CPU cycles with AnyEvent's pure perl loop and almost 3000000 CPU
1533	cycles with POE.	2128	cycles with POE.
1534		2129
1535	C<EV> is the sole leader regarding speed and memory use, which are both	2130	C<EV> is the sole leader regarding speed and memory use, which are both
1536	maximal/minimal, respectively. Even when going through AnyEvent, it uses	2131	maximal/minimal, respectively. When using the L<AE> API there is zero
		2132	overhead (when going through the AnyEvent API create is about 5-6 times
		2133	slower, with other times being equal, so still uses far less memory than
1537	far less memory than any other event loop and is still faster than Event	2134	any other event loop and is still faster than Event natively).
1538	natively.
1539		2135
1540	The pure perl implementation is hit in a few sweet spots (both the	2136	The pure perl implementation is hit in a few sweet spots (both the
1541	constant timeout and the use of a single fd hit optimisations in the perl	2137	constant timeout and the use of a single fd hit optimisations in the perl
1542	interpreter and the backend itself). Nevertheless this shows that it	2138	interpreter and the backend itself). Nevertheless this shows that it
1543	adds very little overhead in itself. Like any select-based backend its	2139	adds very little overhead in itself. Like any select-based backend its
1544	performance becomes really bad with lots of file descriptors (and few of	2140	performance becomes really bad with lots of file descriptors (and few of
1545	them active), of course, but this was not subject of this benchmark.	2141	them active), of course, but this was not subject of this benchmark.
1546		2142
1547	The C<Event> module has a relatively high setup and callback invocation	2143	The C<Event> module has a relatively high setup and callback invocation
1548	cost, but overall scores in on the third place.	2144	cost, but overall scores in on the third place.
		2145
		2146	C<IO::Async> performs admirably well, about on par with C<Event>, even
		2147	when using its pure perl backend.
1549		2148
1550	C<Glib>'s memory usage is quite a bit higher, but it features a	2149	C<Glib>'s memory usage is quite a bit higher, but it features a
1551	faster callback invocation and overall ends up in the same class as	2150	faster callback invocation and overall ends up in the same class as
1552	C<Event>. However, Glib scales extremely badly, doubling the number of	2151	C<Event>. However, Glib scales extremely badly, doubling the number of
1553	watchers increases the processing time by more than a factor of four,	2152	watchers increases the processing time by more than a factor of four,
…		…
1614	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100	2213	In this benchmark, we use 10000 socket pairs (20000 sockets), of which 100
1615	(1%) are active. This mirrors the activity of large servers with many	2214	(1%) are active. This mirrors the activity of large servers with many
1616	connections, most of which are idle at any one point in time.	2215	connections, most of which are idle at any one point in time.
1617		2216
1618	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent	2217	Source code for this benchmark is found as F<eg/bench2> in the AnyEvent
1619	distribution.	2218	distribution. It uses the L<AE> interface, which makes a real difference
		2219	for the EV and Perl backends only.
1620		2220
1621	=head3 Explanation of the columns	2221	=head3 Explanation of the columns
1622		2222
1623	I<sockets> is the number of sockets, and twice the number of "servers" (as	2223	I<sockets> is the number of sockets, and twice the number of "servers" (as
1624	each server has a read and write socket end).	2224	each server has a read and write socket end).
…		…
1631	it to another server. This includes deleting the old timeout and creating	2231	it to another server. This includes deleting the old timeout and creating
1632	a new one that moves the timeout into the future.	2232	a new one that moves the timeout into the future.
1633		2233
1634	=head3 Results	2234	=head3 Results
1635		2235
1636	name sockets create request	2236	name sockets create request
1637	EV 20000 69.01 11.16	2237	EV 20000 62.66 7.99
1638	Perl 20000 73.32 35.87	2238	Perl 20000 68.32 32.64
1639	Event 20000 212.62 257.32	2239	IOAsync 20000 174.06 101.15 epoll
1640	Glib 20000 651.16 1896.30	2240	IOAsync 20000 174.67 610.84 poll
		2241	Event 20000 202.69 242.91
		2242	Glib 20000 557.01 1689.52
1641	POE 20000 349.67 12317.24 uses POE::Loop::Event	2243	POE 20000 341.54 12086.32 uses POE::Loop::Event
1642		2244
1643	=head3 Discussion	2245	=head3 Discussion
1644		2246
1645	This benchmark I<does> measure scalability and overall performance of the	2247	This benchmark I<does> measure scalability and overall performance of the
1646	particular event loop.	2248	particular event loop.
…		…
1648	EV is again fastest. Since it is using epoll on my system, the setup time	2250	EV is again fastest. Since it is using epoll on my system, the setup time
1649	is relatively high, though.	2251	is relatively high, though.
1650		2252
1651	Perl surprisingly comes second. It is much faster than the C-based event	2253	Perl surprisingly comes second. It is much faster than the C-based event
1652	loops Event and Glib.	2254	loops Event and Glib.
		2255
		2256	IO::Async performs very well when using its epoll backend, and still quite
		2257	good compared to Glib when using its pure perl backend.
1653		2258
1654	Event suffers from high setup time as well (look at its code and you will	2259	Event suffers from high setup time as well (look at its code and you will
1655	understand why). Callback invocation also has a high overhead compared to	2260	understand why). Callback invocation also has a high overhead compared to
1656	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2261	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1657	uses select or poll in basically all documented configurations.	2262	uses select or poll in basically all documented configurations.
…		…
1720	=item * C-based event loops perform very well with small number of	2325	=item * C-based event loops perform very well with small number of
1721	watchers, as the management overhead dominates.	2326	watchers, as the management overhead dominates.
1722		2327
1723	=back	2328	=back
1724		2329
		2330	=head2 THE IO::Lambda BENCHMARK
		2331
		2332	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2333	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2334	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2335	shouldn't come as a surprise to anybody). As such, the benchmark is
		2336	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2337	very optimal. But how would AnyEvent compare when used without the extra
		2338	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2339
		2340	The benchmark itself creates an echo-server, and then, for 500 times,
		2341	connects to the echo server, sends a line, waits for the reply, and then
		2342	creates the next connection. This is a rather bad benchmark, as it doesn't
		2343	test the efficiency of the framework or much non-blocking I/O, but it is a
		2344	benchmark nevertheless.
		2345
		2346	name runtime
		2347	Lambda/select 0.330 sec
		2348	+ optimized 0.122 sec
		2349	Lambda/AnyEvent 0.327 sec
		2350	+ optimized 0.138 sec
		2351	Raw sockets/select 0.077 sec
		2352	POE/select, components 0.662 sec
		2353	POE/select, raw sockets 0.226 sec
		2354	POE/select, optimized 0.404 sec
		2355
		2356	AnyEvent/select/nb 0.085 sec
		2357	AnyEvent/EV/nb 0.068 sec
		2358	+state machine 0.134 sec
		2359
		2360	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2361	benchmarks actually make blocking connects and use 100% blocking I/O,
		2362	defeating the purpose of an event-based solution. All of the newly
		2363	written AnyEvent benchmarks use 100% non-blocking connects (using
		2364	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2365	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2366	generally require a lot more bookkeeping and event handling than blocking
		2367	connects (which involve a single syscall only).
		2368
		2369	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2370	offers similar expressive power as POE and IO::Lambda, using conventional
		2371	Perl syntax. This means that both the echo server and the client are 100%
		2372	non-blocking, further placing it at a disadvantage.
		2373
		2374	As you can see, the AnyEvent + EV combination even beats the
		2375	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2376	backend easily beats IO::Lambda and POE.
		2377
		2378	And even the 100% non-blocking version written using the high-level (and
		2379	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2380	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2381	in a non-blocking way.
		2382
		2383	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2384	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2385	part of the IO::lambda distribution and were used without any changes.
		2386
		2387
		2388	=head1 SIGNALS
		2389
		2390	AnyEvent currently installs handlers for these signals:
		2391
		2392	=over 4
		2393
		2394	=item SIGCHLD
		2395
		2396	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2397	emulation for event loops that do not support them natively. Also, some
		2398	event loops install a similar handler.
		2399
		2400	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2401	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2402
		2403	=item SIGPIPE
		2404
		2405	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2406	when AnyEvent gets loaded.
		2407
		2408	The rationale for this is that AnyEvent users usually do not really depend
		2409	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2410	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2411	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2412	some random socket.
		2413
		2414	The rationale for installing a no-op handler as opposed to ignoring it is
		2415	that this way, the handler will be restored to defaults on exec.
		2416
		2417	Feel free to install your own handler, or reset it to defaults.
		2418
		2419	=back
		2420
		2421	=cut
		2422
		2423	undef $SIG{CHLD}
		2424	if $SIG{CHLD} eq 'IGNORE';
		2425
		2426	$SIG{PIPE} = sub { }
		2427	unless defined $SIG{PIPE};
		2428
		2429	=head1 RECOMMENDED/OPTIONAL MODULES
		2430
		2431	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2432	it's built-in modules) are required to use it.
		2433
		2434	That does not mean that AnyEvent won't take advantage of some additional
		2435	modules if they are installed.
		2436
		2437	This section epxlains which additional modules will be used, and how they
		2438	affect AnyEvent's operetion.
		2439
		2440	=over 4
		2441
		2442	=item L<Async::Interrupt>
		2443
		2444	This slightly arcane module is used to implement fast signal handling: To
		2445	my knowledge, there is no way to do completely race-free and quick
		2446	signal handling in pure perl. To ensure that signals still get
		2447	delivered, AnyEvent will start an interval timer to wake up perl (and
		2448	catch the signals) with some delay (default is 10 seconds, look for
		2449	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2450
		2451	If this module is available, then it will be used to implement signal
		2452	catching, which means that signals will not be delayed, and the event loop
		2453	will not be interrupted regularly, which is more efficient (And good for
		2454	battery life on laptops).
		2455
		2456	This affects not just the pure-perl event loop, but also other event loops
		2457	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2458
		2459	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2460	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2461	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2462	does nothing for those backends.
		2463
		2464	=item L<EV>
		2465
		2466	This module isn't really "optional", as it is simply one of the backend
		2467	event loops that AnyEvent can use. However, it is simply the best event
		2468	loop available in terms of features, speed and stability: It supports
		2469	the AnyEvent API optimally, implements all the watcher types in XS, does
		2470	automatic timer adjustments even when no monotonic clock is available,
		2471	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2472	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2473	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2474
		2475	=item L<Guard>
		2476
		2477	The guard module, when used, will be used to implement
		2478	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2479	lot less memory), but otherwise doesn't affect guard operation much. It is
		2480	purely used for performance.
		2481
		2482	=item L<JSON> and L<JSON::XS>
		2483
		2484	This module is required when you want to read or write JSON data via
		2485	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2486	advantage of the ultra-high-speed L<JSON::XS> module when it is installed.
		2487
		2488	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2489	installed.
		2490
		2491	=item L<Net::SSLeay>
		2492
		2493	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2494	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2495	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2496
		2497	=item L<Time::HiRes>
		2498
		2499	This module is part of perl since release 5.008. It will be used when the
		2500	chosen event library does not come with a timing source on it's own. The
		2501	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2502	try to use a monotonic clock for timing stability.
		2503
		2504	=back
		2505
1725		2506
1726	=head1 FORK	2507	=head1 FORK
1727		2508
1728	Most event libraries are not fork-safe. The ones who are usually are	2509	Most event libraries are not fork-safe. The ones who are usually are
1729	because they rely on inefficient but fork-safe C<select> or C<poll>	2510	because they rely on inefficient but fork-safe C<select> or C<poll>
1730	calls. Only L<EV> is fully fork-aware.	2511	calls. Only L<EV> is fully fork-aware.
1731		2512
1732	If you have to fork, you must either do so I<before> creating your first	2513	If you have to fork, you must either do so I<before> creating your first
1733	watcher OR you must not use AnyEvent at all in the child.	2514	watcher OR you must not use AnyEvent at all in the child OR you must do
		2515	something completely out of the scope of AnyEvent.
1734		2516
1735		2517
1736	=head1 SECURITY CONSIDERATIONS	2518	=head1 SECURITY CONSIDERATIONS
1737		2519
1738	AnyEvent can be forced to load any event model via	2520	AnyEvent can be forced to load any event model via
…		…
1750	use AnyEvent;	2532	use AnyEvent;
1751		2533
1752	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2534	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1753	be used to probe what backend is used and gain other information (which is	2535	be used to probe what backend is used and gain other information (which is
1754	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and	2536	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1755	$ENV{PERL_ANYEGENT_STRICT}.	2537	$ENV{PERL_ANYEVENT_STRICT}.
		2538
		2539	Note that AnyEvent will remove I<all> environment variables starting with
		2540	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2541	enabled.
1756		2542
1757		2543
1758	=head1 BUGS	2544	=head1 BUGS
1759		2545
1760	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2546	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1761	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2547	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1762	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2548	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1763	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2549	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1764	pronounced).	2550	pronounced).
1765		2551
1766		2552
1767	=head1 SEE ALSO	2553	=head1 SEE ALSO
1768		2554
…		…
1772	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2558	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1773		2559
1774	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2560	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1775	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2561	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1776	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2562	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1777	L<AnyEvent::Impl::POE>.	2563	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>, L<Anyevent::Impl::Irssi>.
1778		2564
1779	Non-blocking file handles, sockets, TCP clients and	2565	Non-blocking file handles, sockets, TCP clients and
1780	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2566	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1781		2567
1782	Asynchronous DNS: L<AnyEvent::DNS>.	2568	Asynchronous DNS: L<AnyEvent::DNS>.
1783		2569
1784	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2570	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2571	L<Coro::Event>,
1785		2572
1786	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2573	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2574	L<AnyEvent::HTTP>.
1787		2575
1788		2576
1789	=head1 AUTHOR	2577	=head1 AUTHOR
1790		2578
1791	Marc Lehmann <schmorp@schmorp.de>	2579	Marc Lehmann <schmorp@schmorp.de>

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