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Revision 1.173 by root, Mon Jul 21 03:47:22 2008 UTC vs.
Revision 1.247 by root, Sat Jul 18 22:24:17 2009 UTC

1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent - provide framework for multiple event loops	3	AnyEvent - provide framework for multiple event loops
4		4
5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt, POE - various supported event loops	5	EV, Event, Glib, Tk, Perl, Event::Lib, Qt and POE are various supported
		6	event loops.
6		7
7	=head1 SYNOPSIS	8	=head1 SYNOPSIS
8		9
9	use AnyEvent;	10	use AnyEvent;
10		11
		12	# file descriptor readable
11	my $w = AnyEvent->io (fh => $fh, poll => "r|w", cb => sub { ... });	13	my $w = AnyEvent->io (fh => $fh, poll => "r", cb => sub { ... });
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 $condvar gets ->send
29	# use a condvar in callback mode:	37	# use a condvar in callback mode:
…		…
137	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
138	creating a watcher it will immediately "watch" for events and invoke the	146	creating a watcher it will immediately "watch" for events and invoke the
139	callback when the event occurs (of course, only when the event model	147	callback when the event occurs (of course, only when the event model
140	is in control).	148	is in control).
141		149
		150	Note that B<callbacks must not permanently change global variables>
		151	potentially in use by the event loop (such as C<$_> or C<$[>) and that B<<
		152	callbacks must not C<die> >>. The former is good programming practise in
		153	Perl and the latter stems from the fact that exception handling differs
		154	widely between event loops.
		155
142	To disable the watcher you have to destroy it (e.g. by setting the	156	To disable the watcher you have to destroy it (e.g. by setting the
143	variable you store it in to C<undef> or otherwise deleting all references	157	variable you store it in to C<undef> or otherwise deleting all references
144	to it).	158	to it).
145		159
146	All watchers are created by calling a method on the C<AnyEvent> class.	160	All watchers are created by calling a method on the C<AnyEvent> class.
…		…
162	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
163		177
164	You can create an I/O watcher by calling the C<< AnyEvent->io >> method	178	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
165	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
166		180
167	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for events	181	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>	182	for events (AnyEvent might or might not keep a reference to this file
		183	handle). Note that only file handles pointing to things for which
		184	non-blocking operation makes sense are allowed. This includes sockets,
		185	most character devices, pipes, fifos and so on, but not for example files
		186	or block devices.
		187
169	must be a string that is either C<r> or C<w>, which creates a watcher	188	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	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
171	callback to invoke each time the file handle becomes ready.	191	C<cb> is the callback to invoke each time the file handle becomes ready.
172		192
173	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
174	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
175	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
176		196
…		…
308	In either case, if you care (and in most cases, you don't), then you	328	In either case, if you care (and in most cases, you don't), then you
309	can get whatever behaviour you want with any event loop, by taking the	329	can get whatever behaviour you want with any event loop, by taking the
310	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
311	account.	331	account.
312		332
		333	=item AnyEvent->now_update
		334
		335	Some event loops (such as L<EV> or L<AnyEvent::Impl::Perl>) cache
		336	the current time for each loop iteration (see the discussion of L<<
		337	AnyEvent->now >>, above).
		338
		339	When a callback runs for a long time (or when the process sleeps), then
		340	this "current" time will differ substantially from the real time, which
		341	might affect timers and time-outs.
		342
		343	When this is the case, you can call this method, which will update the
		344	event loop's idea of "current time".
		345
		346	Note that updating the time I<might> cause some events to be handled.
		347
313	=back	348	=back
314		349
315	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
316		351
317	You can watch for signals using a signal watcher, C<signal> is the signal	352	You can watch for signals using a signal watcher, C<signal> is the signal
…		…
326	invocation, and callback invocation will be synchronous. Synchronous means	361	invocation, and callback invocation will be synchronous. Synchronous means
327	that it might take a while until the signal gets handled by the process,	362	that it might take a while until the signal gets handled by the process,
328	but it is guaranteed not to interrupt any other callbacks.	363	but it is guaranteed not to interrupt any other callbacks.
329		364
330	The main advantage of using these watchers is that you can share a signal	365	The main advantage of using these watchers is that you can share a signal
331	between multiple watchers.	366	between multiple watchers, and AnyEvent will ensure that signals will not
		367	interrupt your program at bad times.
332		368
333	This watcher might use C<%SIG>, so programs overwriting those signals	369	This watcher might use C<%SIG> (depending on the event loop used),
334	directly will likely not work correctly.	370	so programs overwriting those signals directly will likely not work
		371	correctly.
335		372
336	Example: exit on SIGINT	373	Example: exit on SIGINT
337		374
338	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });	375	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
339		376
		377	=head3 Signal Races, Delays and Workarounds
		378
		379	Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
		380	callbacks to signals in a generic way, which is a pity, as you cannot do
		381	race-free signal handling in perl. AnyEvent will try to do it's best, but
		382	in some cases, signals will be delayed. The maximum time a signal might
		383	be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
		384	seconds). This variable can be changed only before the first signal
		385	watcher is created, and should be left alone otherwise. Higher values
		386	will cause fewer spurious wake-ups, which is better for power and CPU
		387	saving. All these problems can be avoided by installing the optional
		388	L<Async::Interrupt> module. This will not work with inherently broken
		389	event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
		390	currently, as POE does it's own workaround with one-second latency). With
		391	those, you just have to suffer the delays.
		392
340	=head2 CHILD PROCESS WATCHERS	393	=head2 CHILD PROCESS WATCHERS
341		394
342	You can also watch on a child process exit and catch its exit status.	395	You can also watch on a child process exit and catch its exit status.
343		396
344	The child process is specified by the C<pid> argument (if set to C<0>, it	397	The child process is specified by the C<pid> argument (if set to C<0>, it
345	watches for any child process exit). The watcher will trigger as often	398	watches for any child process exit). The watcher will triggered only when
346	as status change for the child are received. This works by installing a	399	the child process has finished and an exit status is available, not on
347	signal handler for C<SIGCHLD>. The callback will be called with the pid	400	any trace events (stopped/continued).
348	and exit status (as returned by waitpid), so unlike other watcher types,	401
349	you I<can> rely on child watcher callback arguments.	402	The callback will be called with the pid and exit status (as returned by
		403	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		404	callback arguments.
		405
		406	This watcher type works by installing a signal handler for C<SIGCHLD>,
		407	and since it cannot be shared, nothing else should use SIGCHLD or reap
		408	random child processes (waiting for specific child processes, e.g. inside
		409	C<system>, is just fine).
350		410
351	There is a slight catch to child watchers, however: you usually start them	411	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	412	I<after> the child process was created, and this means the process could
353	have exited already (and no SIGCHLD will be sent anymore).	413	have exited already (and no SIGCHLD will be sent anymore).
354		414
355	Not all event models handle this correctly (POE doesn't), but even for	415	Not all event models handle this correctly (neither POE nor IO::Async do,
		416	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	417	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).	418	the process exits (i.e. before you fork in the first place). AnyEvent's
		419	pure perl event loop handles all cases correctly regardless of when you
		420	start the watcher.
358		421
359	This means you cannot create a child watcher as the very first thing in an	422	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	423	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>).	424	watcher before you C<fork> the child (alternatively, you can call
		425	C<AnyEvent::detect>).
		426
		427	As most event loops do not support waiting for child events, they will be
		428	emulated by AnyEvent in most cases, in which the latency and race problems
		429	mentioned in the description of signal watchers apply.
362		430
363	Example: fork a process and wait for it	431	Example: fork a process and wait for it
364		432
365	my $done = AnyEvent->condvar;	433	my $done = AnyEvent->condvar;
366		434
…		…
376	);	444	);
377		445
378	# do something else, then wait for process exit	446	# do something else, then wait for process exit
379	$done->recv;	447	$done->recv;
380		448
		449	=head2 IDLE WATCHERS
		450
		451	Sometimes there is a need to do something, but it is not so important
		452	to do it instantly, but only when there is nothing better to do. This
		453	"nothing better to do" is usually defined to be "no other events need
		454	attention by the event loop".
		455
		456	Idle watchers ideally get invoked when the event loop has nothing
		457	better to do, just before it would block the process to wait for new
		458	events. Instead of blocking, the idle watcher is invoked.
		459
		460	Most event loops unfortunately do not really support idle watchers (only
		461	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		462	will simply call the callback "from time to time".
		463
		464	Example: read lines from STDIN, but only process them when the
		465	program is otherwise idle:
		466
		467	my @lines; # read data
		468	my $idle_w;
		469	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		470	push @lines, scalar <STDIN>;
		471
		472	# start an idle watcher, if not already done
		473	$idle_w ||= AnyEvent->idle (cb => sub {
		474	# handle only one line, when there are lines left
		475	if (my $line = shift @lines) {
		476	print "handled when idle: $line";
		477	} else {
		478	# otherwise disable the idle watcher again
		479	undef $idle_w;
		480	}
		481	});
		482	});
		483
381	=head2 CONDITION VARIABLES	484	=head2 CONDITION VARIABLES
382		485
383	If you are familiar with some event loops you will know that all of them	486	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	487	require you to run some blocking "loop", "run" or similar function that
385	will actively watch for new events and call your callbacks.	488	will actively watch for new events and call your callbacks.
386		489
387	AnyEvent is different, it expects somebody else to run the event loop and	490	AnyEvent is slightly different: it expects somebody else to run the event
388	will only block when necessary (usually when told by the user).	491	loop and will only block when necessary (usually when told by the user).
389		492
390	The instrument to do that is called a "condition variable", so called	493	The instrument to do that is called a "condition variable", so called
391	because they represent a condition that must become true.	494	because they represent a condition that must become true.
392		495
		496	Now is probably a good time to look at the examples further below.
		497
393	Condition variables can be created by calling the C<< AnyEvent->condvar	498	Condition variables can be created by calling the C<< AnyEvent->condvar
394
395	>> method, usually without arguments. The only argument pair allowed is	499	>> 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	500	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	501	becomes true, with the condition variable as the first argument (but not
399	the results).	502	the results).
400		503
401	After creation, the condition variable is "false" until it becomes "true"	504	After creation, the condition variable is "false" until it becomes "true"
…		…
450	after => 1,	553	after => 1,
451	cb => sub { $result_ready->send },	554	cb => sub { $result_ready->send },
452	);	555	);
453		556
454	# this "blocks" (while handling events) till the callback	557	# this "blocks" (while handling events) till the callback
455	# calls send	558	# calls -<send
456	$result_ready->recv;	559	$result_ready->recv;
457		560
458	Example: wait for a timer, but take advantage of the fact that	561	Example: wait for a timer, but take advantage of the fact that condition
459	condition variables are also code references.	562	variables are also callable directly.
460		563
461	my $done = AnyEvent->condvar;	564	my $done = AnyEvent->condvar;
462	my $delay = AnyEvent->timer (after => 5, cb => $done);	565	my $delay = AnyEvent->timer (after => 5, cb => $done);
463	$done->recv;	566	$done->recv;
464		567
…		…
470		573
471	...	574	...
472		575
473	my @info = $couchdb->info->recv;	576	my @info = $couchdb->info->recv;
474		577
475	And this is how you would just ste a callback to be called whenever the	578	And this is how you would just set a callback to be called whenever the
476	results are available:	579	results are available:
477		580
478	$couchdb->info->cb (sub {	581	$couchdb->info->cb (sub {
479	my @info = $_[0]->recv;	582	my @info = $_[0]->recv;
480	});	583	});
…		…
498	immediately from within send.	601	immediately from within send.
499		602
500	Any arguments passed to the C<send> call will be returned by all	603	Any arguments passed to the C<send> call will be returned by all
501	future C<< ->recv >> calls.	604	future C<< ->recv >> calls.
502		605
503	Condition variables are overloaded so one can call them directly	606	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	607	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	608	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		609
512	=item $cv->croak ($error)	610	=item $cv->croak ($error)
513		611
514	Similar to send, but causes all call's to C<< ->recv >> to invoke	612	Similar to send, but causes all call's to C<< ->recv >> to invoke
515	C<Carp::croak> with the given error message/object/scalar.	613	C<Carp::croak> with the given error message/object/scalar.
516		614
517	This can be used to signal any errors to the condition variable	615	This can be used to signal any errors to the condition variable
518	user/consumer.	616	user/consumer. Doing it this way instead of calling C<croak> directly
		617	delays the error detetcion, but has the overwhelmign advantage that it
		618	diagnoses the error at the place where the result is expected, and not
		619	deep in some event clalback without connection to the actual code causing
		620	the problem.
519		621
520	=item $cv->begin ([group callback])	622	=item $cv->begin ([group callback])
521		623
522	=item $cv->end	624	=item $cv->end
523
524	These two methods are EXPERIMENTAL and MIGHT CHANGE.
525		625
526	These two methods can be used to combine many transactions/events into	626	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	627	one. For example, a function that pings many hosts in parallel might want
528	to use a condition variable for the whole process.	628	to use a condition variable for the whole process.
529		629
…		…
531	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	631	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	632	>>, 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	633	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.	634	callback was set, C<send> will be called without any arguments.
535		635
536	Let's clarify this with the ping example:	636	You can think of C<< $cv->send >> giving you an OR condition (one call
		637	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		638	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		639
		640	Let's start with a simple example: you have two I/O watchers (for example,
		641	STDOUT and STDERR for a program), and you want to wait for both streams to
		642	close before activating a condvar:
		643
		644	my $cv = AnyEvent->condvar;
		645
		646	$cv->begin; # first watcher
		647	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		648	defined sysread $fh1, my $buf, 4096
		649	or $cv->end;
		650	});
		651
		652	$cv->begin; # second watcher
		653	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		654	defined sysread $fh2, my $buf, 4096
		655	or $cv->end;
		656	});
		657
		658	$cv->recv;
		659
		660	This works because for every event source (EOF on file handle), there is
		661	one call to C<begin>, so the condvar waits for all calls to C<end> before
		662	sending.
		663
		664	The ping example mentioned above is slightly more complicated, as the
		665	there are results to be passwd back, and the number of tasks that are
		666	begung can potentially be zero:
537		667
538	my $cv = AnyEvent->condvar;	668	my $cv = AnyEvent->condvar;
539		669
540	my %result;	670	my %result;
541	$cv->begin (sub { $cv->send (\%result) });	671	$cv->begin (sub { $cv->send (\%result) });
…		…
561	loop, which serves two important purposes: first, it sets the callback	691	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	692	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	693	C<send> is called even when C<no> hosts are being pinged (the loop
564	doesn't execute once).	694	doesn't execute once).
565		695
566	This is the general pattern when you "fan out" into multiple subrequests:	696	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>	697	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	698	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>.	699	subrequest you start, call C<begin> and for each subrequest you finish,
		700	call C<end>.
570		701
571	=back	702	=back
572		703
573	=head3 METHODS FOR CONSUMERS	704	=head3 METHODS FOR CONSUMERS
574		705
…		…
590	function will call C<croak>.	721	function will call C<croak>.
591		722
592	In list context, all parameters passed to C<send> will be returned,	723	In list context, all parameters passed to C<send> will be returned,
593	in scalar context only the first one will be returned.	724	in scalar context only the first one will be returned.
594		725
		726	Note that doing a blocking wait in a callback is not supported by any
		727	event loop, that is, recursive invocation of a blocking C<< ->recv
		728	>> is not allowed, and the C<recv> call will C<croak> if such a
		729	condition is detected. This condition can be slightly loosened by using
		730	L<Coro::AnyEvent>, which allows you to do a blocking C<< ->recv >> from
		731	any thread that doesn't run the event loop itself.
		732
595	Not all event models support a blocking wait - some die in that case	733	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	734	(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	735	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	736	caller decide whether the call will block or not (for example, by coupling
599	condition variables with some kind of request results and supporting	737	condition variables with some kind of request results and supporting
600	callbacks so the caller knows that getting the result will not block,	738	callbacks so the caller knows that getting the result will not block,
601	while still supporting blocking waits if the caller so desires).	739	while still supporting blocking waits if the caller so desires).
602		740
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	741	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	742	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	743	time). This will work even when the event loop does not support blocking
617	waits otherwise.	744	waits otherwise.
618		745
…		…
631	variable itself. Calling C<recv> inside the callback or at any later time	758	variable itself. Calling C<recv> inside the callback or at any later time
632	is guaranteed not to block.	759	is guaranteed not to block.
633		760
634	=back	761	=back
635		762
		763	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		764
		765	The available backend classes are (every class has its own manpage):
		766
		767	=over 4
		768
		769	=item Backends that are autoprobed when no other event loop can be found.
		770
		771	EV is the preferred backend when no other event loop seems to be in
		772	use. If EV is not installed, then AnyEvent will try Event, and, failing
		773	that, will fall back to its own pure-perl implementation, which is
		774	available everywhere as it comes with AnyEvent itself.
		775
		776	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		777	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		778	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		779
		780	=item Backends that are transparently being picked up when they are used.
		781
		782	These will be used when they are currently loaded when the first watcher
		783	is created, in which case it is assumed that the application is using
		784	them. This means that AnyEvent will automatically pick the right backend
		785	when the main program loads an event module before anything starts to
		786	create watchers. Nothing special needs to be done by the main program.
		787
		788	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		789	AnyEvent::Impl::Tk based on Tk, very broken.
		790	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		791	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		792
		793	=item Backends with special needs.
		794
		795	Qt requires the Qt::Application to be instantiated first, but will
		796	otherwise be picked up automatically. As long as the main program
		797	instantiates the application before any AnyEvent watchers are created,
		798	everything should just work.
		799
		800	AnyEvent::Impl::Qt based on Qt.
		801
		802	Support for IO::Async can only be partial, as it is too broken and
		803	architecturally limited to even support the AnyEvent API. It also
		804	is the only event loop that needs the loop to be set explicitly, so
		805	it can only be used by a main program knowing about AnyEvent. See
		806	L<AnyEvent::Impl::Async> for the gory details.
		807
		808	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		809
		810	=item Event loops that are indirectly supported via other backends.
		811
		812	Some event loops can be supported via other modules:
		813
		814	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		815
		816	B<WxWidgets> has no support for watching file handles. However, you can
		817	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		818	polls 20 times per second, which was considered to be too horrible to even
		819	consider for AnyEvent.
		820
		821	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		822	backend, so it can be supported through POE.
		823
		824	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		825	load L<POE> when detecting them, in the hope that POE will pick them up,
		826	in which case everything will be automatic.
		827
		828	=back
		829
636	=head1 GLOBAL VARIABLES AND FUNCTIONS	830	=head1 GLOBAL VARIABLES AND FUNCTIONS
637		831
		832	These are not normally required to use AnyEvent, but can be useful to
		833	write AnyEvent extension modules.
		834
638	=over 4	835	=over 4
639		836
640	=item $AnyEvent::MODEL	837	=item $AnyEvent::MODEL
641		838
642	Contains C<undef> until the first watcher is being created. Then it	839	Contains C<undef> until the first watcher is being created, before the
		840	backend has been autodetected.
		841
643	contains the event model that is being used, which is the name of the	842	Afterwards it contains the event model that is being used, which is the
644	Perl class implementing the model. This class is usually one of the	843	name of the Perl class implementing the model. This class is usually one
645	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	844	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
646	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	845	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
647		846	will be C<urxvt::anyevent>).
648	The known classes so far are:
649
650	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
651	AnyEvent::Impl::Event based on Event, second best choice.
652	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
653	AnyEvent::Impl::Glib based on Glib, third-best choice.
654	AnyEvent::Impl::Tk based on Tk, very bad choice.
655	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
656	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
657	AnyEvent::Impl::POE based on POE, not generic enough for full support.
658
659	There is no support for WxWidgets, as WxWidgets has no support for
660	watching file handles. However, you can use WxWidgets through the
661	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
662	second, which was considered to be too horrible to even consider for
663	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
664	it's adaptor.
665
666	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
667	autodetecting them.
668		847
669	=item AnyEvent::detect	848	=item AnyEvent::detect
670		849
671	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	850	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
672	if necessary. You should only call this function right before you would	851	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	852	have created an AnyEvent watcher anyway, that is, as late as possible at
674	runtime.	853	runtime, and not e.g. while initialising of your module.
		854
		855	If you need to do some initialisation before AnyEvent watchers are
		856	created, use C<post_detect>.
675		857
676	=item $guard = AnyEvent::post_detect { BLOCK }	858	=item $guard = AnyEvent::post_detect { BLOCK }
677		859
678	Arranges for the code block to be executed as soon as the event model is	860	Arranges for the code block to be executed as soon as the event model is
679	autodetected (or immediately if this has already happened).	861	autodetected (or immediately if this has already happened).
		862
		863	The block will be executed I<after> the actual backend has been detected
		864	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		865	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		866	other initialisations - see the sources of L<AnyEvent::Strict> or
		867	L<AnyEvent::AIO> to see how this is used.
		868
		869	The most common usage is to create some global watchers, without forcing
		870	event module detection too early, for example, L<AnyEvent::AIO> creates
		871	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		872	avoid autodetecting the event module at load time.
680		873
681	If called in scalar or list context, then it creates and returns an object	874	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	875	that automatically removes the callback again when it is destroyed. See
683	L<Coro::BDB> for a case where this is useful.	876	L<Coro::BDB> for a case where this is useful.
684		877
…		…
687	If there are any code references in this array (you can C<push> to it	880	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	881	before or after loading AnyEvent), then they will called directly after
689	the event loop has been chosen.	882	the event loop has been chosen.
690		883
691	You should check C<$AnyEvent::MODEL> before adding to this array, though:	884	You should check C<$AnyEvent::MODEL> before adding to this array, though:
692	if it contains a true value then the event loop has already been detected,	885	if it is defined then the event loop has already been detected, and the
693	and the array will be ignored.	886	array will be ignored.
694		887
695	Best use C<AnyEvent::post_detect { BLOCK }> instead.	888	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		889	it,as it takes care of these details.
		890
		891	This variable is mainly useful for modules that can do something useful
		892	when AnyEvent is used and thus want to know when it is initialised, but do
		893	not need to even load it by default. This array provides the means to hook
		894	into AnyEvent passively, without loading it.
696		895
697	=back	896	=back
698		897
699	=head1 WHAT TO DO IN A MODULE	898	=head1 WHAT TO DO IN A MODULE
700		899
…		…
755		954
756		955
757	=head1 OTHER MODULES	956	=head1 OTHER MODULES
758		957
759	The following is a non-exhaustive list of additional modules that use	958	The following is a non-exhaustive list of additional modules that use
760	AnyEvent and can therefore be mixed easily with other AnyEvent modules	959	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	960	modules and other event loops in the same program. Some of the modules
762	available via CPAN.	961	come with AnyEvent, most are available via CPAN.
763		962
764	=over 4	963	=over 4
765		964
766	=item L<AnyEvent::Util>	965	=item L<AnyEvent::Util>
767		966
…		…
776		975
777	=item L<AnyEvent::Handle>	976	=item L<AnyEvent::Handle>
778		977
779	Provide read and write buffers, manages watchers for reads and writes,	978	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	979	supports raw and formatted I/O, I/O queued and fully transparent and
781	non-blocking SSL/TLS.	980	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
782		981
783	=item L<AnyEvent::DNS>	982	=item L<AnyEvent::DNS>
784		983
785	Provides rich asynchronous DNS resolver capabilities.	984	Provides rich asynchronous DNS resolver capabilities.
786		985
…		…
814		1013
815	=item L<AnyEvent::GPSD>	1014	=item L<AnyEvent::GPSD>
816		1015
817	A non-blocking interface to gpsd, a daemon delivering GPS information.	1016	A non-blocking interface to gpsd, a daemon delivering GPS information.
818		1017
		1018	=item L<AnyEvent::IRC>
		1019
		1020	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1021
		1022	=item L<AnyEvent::XMPP>
		1023
		1024	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1025	Net::XMPP2>.
		1026
819	=item L<AnyEvent::IGS>	1027	=item L<AnyEvent::IGS>
820		1028
821	A non-blocking interface to the Internet Go Server protocol (used by	1029	A non-blocking interface to the Internet Go Server protocol (used by
822	L<App::IGS>).	1030	L<App::IGS>).
823		1031
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>	1032	=item L<Net::FCP>
833		1033
834	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1034	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
835	of AnyEvent.	1035	of AnyEvent.
836		1036
…		…
840		1040
841	=item L<Coro>	1041	=item L<Coro>
842		1042
843	Has special support for AnyEvent via L<Coro::AnyEvent>.	1043	Has special support for AnyEvent via L<Coro::AnyEvent>.
844		1044
845	=item L<IO::Lambda>
846
847	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
848
849	=back	1045	=back
850		1046
851	=cut	1047	=cut
852		1048
853	package AnyEvent;	1049	package AnyEvent;
854		1050
		1051	# basically a tuned-down version of common::sense
		1052	sub common_sense {
855	no warnings;	1053	# no warnings
856	use strict;	1054	${^WARNING_BITS} ^= ${^WARNING_BITS};
		1055	# use strict vars subs
		1056	$^H |= 0x00000600;
		1057	}
857		1058
		1059	BEGIN { AnyEvent::common_sense }
		1060
858	use Carp;	1061	use Carp ();
859		1062
860	our $VERSION = 4.22;	1063	our $VERSION = 4.85;
861	our $MODEL;	1064	our $MODEL;
862		1065
863	our $AUTOLOAD;	1066	our $AUTOLOAD;
864	our @ISA;	1067	our @ISA;
865		1068
866	our @REGISTRY;	1069	our @REGISTRY;
867		1070
868	our $WIN32;	1071	our $WIN32;
869		1072
		1073	our $VERBOSE;
		1074
870	BEGIN {	1075	BEGIN {
871	my $win32 = ! ! ($^O =~ /mswin32/i);	1076	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
872	eval "sub WIN32(){ $win32 }";	1077	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
873	}
874		1078
		1079	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1080	if ${^TAINT};
		1081
875	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1082	$VERBOSE = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		1083
		1084	}
		1085
		1086	our $MAX_SIGNAL_LATENCY = 10;
876		1087
877	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred	1088	our %PROTOCOL; # (ipv4|ipv6) => (1|2), higher numbers are preferred
878		1089
879	{	1090	{
880	my $idx;	1091	my $idx;
…		…
888	[Event:: => AnyEvent::Impl::Event::],	1099	[Event:: => AnyEvent::Impl::Event::],
889	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1100	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
890	# everything below here will not be autoprobed	1101	# everything below here will not be autoprobed
891	# as the pureperl backend should work everywhere	1102	# as the pureperl backend should work everywhere
892	# and is usually faster	1103	# and is usually faster
893	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
894	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1104	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
895	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1105	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1106	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
896	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1107	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
897	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1108	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
898	[Wx:: => AnyEvent::Impl::POE::],	1109	[Wx:: => AnyEvent::Impl::POE::],
899	[Prima:: => AnyEvent::Impl::POE::],	1110	[Prima:: => AnyEvent::Impl::POE::],
		1111	# IO::Async is just too broken - we would need workarounds for its
		1112	# byzantine signal and broken child handling, among others.
		1113	# IO::Async is rather hard to detect, as it doesn't have any
		1114	# obvious default class.
		1115	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1116	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1117	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
900	);	1118	);
901		1119
902	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1120	our %method = map +($_ => 1),
		1121	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
903		1122
904	our @post_detect;	1123	our @post_detect;
905		1124
906	sub post_detect(&) {	1125	sub post_detect(&) {
907	my ($cb) = @_;	1126	my ($cb) = @_;
…		…
912	1	1131	1
913	} else {	1132	} else {
914	push @post_detect, $cb;	1133	push @post_detect, $cb;
915		1134
916	defined wantarray	1135	defined wantarray
917	? bless \$cb, "AnyEvent::Util::PostDetect"	1136	? bless \$cb, "AnyEvent::Util::postdetect"
918	: ()	1137	: ()
919	}	1138	}
920	}	1139	}
921		1140
922	sub AnyEvent::Util::PostDetect::DESTROY {	1141	sub AnyEvent::Util::postdetect::DESTROY {
923	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1142	@post_detect = grep $_ != ${$_[0]}, @post_detect;
924	}	1143	}
925		1144
926	sub detect() {	1145	sub detect() {
927	unless ($MODEL) {	1146	unless ($MODEL) {
928	no strict 'refs';
929	local $SIG{__DIE__};	1147	local $SIG{__DIE__};
930		1148
931	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {	1149	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
932	my $model = "AnyEvent::Impl::$1";	1150	my $model = "AnyEvent::Impl::$1";
933	if (eval "require $model") {	1151	if (eval "require $model") {
934	$MODEL = $model;	1152	$MODEL = $model;
935	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;	1153	warn "AnyEvent: loaded model '$model' (forced by \$ENV{PERL_ANYEVENT_MODEL}), using it.\n" if $VERBOSE >= 2;
936	} else {	1154	} else {
937	warn "AnyEvent: unable to load model '$model' (from \$PERL_ANYEVENT_MODEL):\n$@" if $verbose;	1155	warn "AnyEvent: unable to load model '$model' (from \$ENV{PERL_ANYEVENT_MODEL}):\n$@" if $VERBOSE;
938	}	1156	}
939	}	1157	}
940		1158
941	# check for already loaded models	1159	# check for already loaded models
942	unless ($MODEL) {	1160	unless ($MODEL) {
943	for (@REGISTRY, @models) {	1161	for (@REGISTRY, @models) {
944	my ($package, $model) = @$_;	1162	my ($package, $model) = @$_;
945	if (${"$package\::VERSION"} > 0) {	1163	if (${"$package\::VERSION"} > 0) {
946	if (eval "require $model") {	1164	if (eval "require $model") {
947	$MODEL = $model;	1165	$MODEL = $model;
948	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;	1166	warn "AnyEvent: autodetected model '$model', using it.\n" if $VERBOSE >= 2;
949	last;	1167	last;
950	}	1168	}
951	}	1169	}
952	}	1170	}
953		1171
…		…
958	my ($package, $model) = @$_;	1176	my ($package, $model) = @$_;
959	if (eval "require $package"	1177	if (eval "require $package"
960	and ${"$package\::VERSION"} > 0	1178	and ${"$package\::VERSION"} > 0
961	and eval "require $model") {	1179	and eval "require $model") {
962	$MODEL = $model;	1180	$MODEL = $model;
963	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;	1181	warn "AnyEvent: autoprobed model '$model', using it.\n" if $VERBOSE >= 2;
964	last;	1182	last;
965	}	1183	}
966	}	1184	}
967		1185
968	$MODEL	1186	$MODEL
969	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1187	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
970	}	1188	}
971	}	1189	}
972		1190
973	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1191	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
974		1192
…		…
984		1202
985	sub AUTOLOAD {	1203	sub AUTOLOAD {
986	(my $func = $AUTOLOAD) =~ s/.*://;	1204	(my $func = $AUTOLOAD) =~ s/.*://;
987		1205
988	$method{$func}	1206	$method{$func}
989	or croak "$func: not a valid method for AnyEvent objects";	1207	or Carp::croak "$func: not a valid method for AnyEvent objects";
990		1208
991	detect unless $MODEL;	1209	detect unless $MODEL;
992		1210
993	my $class = shift;	1211	my $class = shift;
994	$class->$func (@_);	1212	$class->$func (@_);
995	}	1213	}
996		1214
997	# utility function to dup a filehandle. this is used by many backends	1215	# utility function to dup a filehandle. this is used by many backends
998	# to support binding more than one watcher per filehandle (they usually	1216	# 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).	1217	# allow only one watcher per fd, so we dup it to get a different one).
1000	sub _dupfh($$$$) {	1218	sub _dupfh($$;$$) {
1001	my ($poll, $fh, $r, $w) = @_;	1219	my ($poll, $fh, $r, $w) = @_;
1002		1220
1003	require Fcntl;
1004
1005	# cygwin requires the fh mode to be matching, unix doesn't	1221	# cygwin requires the fh mode to be matching, unix doesn't
1006	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1222	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		1223
1010	open my $fh2, "$mode&" . fileno $fh	1224	open my $fh2, $mode, $fh
1011	or die "cannot dup() filehandle: $!";	1225	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1012		1226
1013	# we assume CLOEXEC is already set by perl in all important cases	1227	# we assume CLOEXEC is already set by perl in all important cases
1014		1228
1015	($fh2, $rw)	1229	($fh2, $rw)
1016	}	1230	}
1017		1231
1018	package AnyEvent::Base;	1232	package AnyEvent::Base;
1019		1233
1020	# default implementation for now and time	1234	# default implementations for many methods
1021		1235
1022	use Time::HiRes ();	1236	sub _time {
		1237	# probe for availability of Time::HiRes
		1238	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1239	warn "AnyEvent: using Time::HiRes for sub-second timing accuracy.\n" if $VERBOSE >= 8;
		1240	*_time = \&Time::HiRes::time;
		1241	# if (eval "use POSIX (); (POSIX::times())...
		1242	} else {
		1243	warn "AnyEvent: using built-in time(), WARNING, no sub-second resolution!\n" if $VERBOSE;
		1244	*_time = sub { time }; # epic fail
		1245	}
1023		1246
1024	sub time { Time::HiRes::time }	1247	&_time
1025	sub now { Time::HiRes::time }	1248	}
		1249
		1250	sub time { _time }
		1251	sub now { _time }
		1252	sub now_update { }
1026		1253
1027	# default implementation for ->condvar	1254	# default implementation for ->condvar
1028		1255
1029	sub condvar {	1256	sub condvar {
1030	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1257	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1031	}	1258	}
1032		1259
1033	# default implementation for ->signal	1260	# default implementation for ->signal
1034		1261
1035	our %SIG_CB;	1262	our $HAVE_ASYNC_INTERRUPT;
		1263	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1264	our (%SIG_ASY, %SIG_ASY_W);
		1265	our ($SIG_COUNT, $SIG_TW);
1036		1266
		1267	sub _signal_exec {
		1268	$HAVE_ASYNC_INTERRUPT
		1269	? $SIGPIPE_R->drain
		1270	: sysread $SIGPIPE_R, my $dummy, 9;
		1271
		1272	while (%SIG_EV) {
		1273	for (keys %SIG_EV) {
		1274	delete $SIG_EV{$_};
		1275	$_->() for values %{ $SIG_CB{$_} || {} };
		1276	}
		1277	}
		1278	}
		1279
		1280	# install a dumym wakeupw atcher to reduce signal catching latency
		1281	sub _sig_add() {
		1282	unless ($SIG_COUNT++) {
		1283	# try to align timer on a full-second boundary, if possible
		1284	my $NOW = AnyEvent->now;
		1285
		1286	$SIG_TW = AnyEvent->timer (
		1287	after => $MAX_SIGNAL_LATENCY - ($NOW - int $NOW),
		1288	interval => $MAX_SIGNAL_LATENCY,
		1289	cb => sub { }, # just for the PERL_ASYNC_CHECK
		1290	);
		1291	}
		1292	}
		1293
		1294	sub _sig_del {
		1295	undef $SIG_TW
		1296	unless --$SIG_COUNT;
		1297	}
		1298
1037	sub signal {	1299	sub _signal {
1038	my (undef, %arg) = @_;	1300	my (undef, %arg) = @_;
1039		1301
1040	my $signal = uc $arg{signal}	1302	my $signal = uc $arg{signal}
1041	or Carp::croak "required option 'signal' is missing";	1303	or Carp::croak "required option 'signal' is missing";
1042		1304
1043	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1305	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		1306
		1307	if ($HAVE_ASYNC_INTERRUPT) {
		1308	# async::interrupt
		1309
		1310	$SIG_ASY{$signal} ||= do {
		1311	my $asy = new Async::Interrupt
		1312	cb => sub { undef $SIG_EV{$signal} },
		1313	signal => $signal,
		1314	pipe => [$SIGPIPE_R->filenos],
		1315	;
		1316	$asy->pipe_autodrain (0);
		1317
		1318	$asy
		1319	};
		1320
		1321	} else {
		1322	# pure perl
		1323
1044	$SIG{$signal} ||= sub {	1324	$SIG{$signal} ||= sub {
1045	$_->() for values %{ $SIG_CB{$signal} || {} };	1325	local $!;
		1326	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1327	undef $SIG_EV{$signal};
		1328	};
		1329
		1330	# can't do signal processing without introducing races in pure perl,
		1331	# so limit the signal latency.
		1332	_sig_add;
1046	};	1333	}
1047		1334
1048	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1335	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1049	}	1336	}
1050		1337
		1338	sub signal {
		1339	# probe for availability of Async::Interrupt
		1340	if (!$ENV{PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT} && eval "use Async::Interrupt 0.6 (); 1") {
		1341	warn "AnyEvent: using Async::Interrupt for race-free signal handling.\n" if $VERBOSE >= 8;
		1342
		1343	$HAVE_ASYNC_INTERRUPT = 1;
		1344	$SIGPIPE_R = new Async::Interrupt::EventPipe;
		1345	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R->fileno, poll => "r", cb => \&_signal_exec);
		1346
		1347	} else {
		1348	warn "AnyEvent: using emulated perl signal handling with latency timer.\n" if $VERBOSE >= 8;
		1349
		1350	require Fcntl;
		1351
		1352	if (AnyEvent::WIN32) {
		1353	require AnyEvent::Util;
		1354
		1355	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1356	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1357	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1358	} else {
		1359	pipe $SIGPIPE_R, $SIGPIPE_W;
		1360	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1361	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1362
		1363	# not strictly required, as $^F is normally 2, but let's make sure...
		1364	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1365	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1366	}
		1367
		1368	$SIGPIPE_R
		1369	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1370
		1371	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1372	}
		1373
		1374	*signal = \&_signal;
		1375	&signal
		1376	}
		1377
1051	sub AnyEvent::Base::Signal::DESTROY {	1378	sub AnyEvent::Base::signal::DESTROY {
1052	my ($signal, $cb) = @{$_[0]};	1379	my ($signal, $cb) = @{$_[0]};
1053		1380
		1381	_sig_del;
		1382
1054	delete $SIG_CB{$signal}{$cb};	1383	delete $SIG_CB{$signal}{$cb};
1055		1384
		1385	$HAVE_ASYNC_INTERRUPT
		1386	? delete $SIG_ASY{$signal}
		1387	: # delete doesn't work with older perls - they then
		1388	# print weird messages, or just unconditionally exit
		1389	# instead of getting the default action.
		1390	undef $SIG{$signal}
1056	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1391	unless keys %{ $SIG_CB{$signal} };
1057	}	1392	}
1058		1393
1059	# default implementation for ->child	1394	# default implementation for ->child
1060		1395
1061	our %PID_CB;	1396	our %PID_CB;
1062	our $CHLD_W;	1397	our $CHLD_W;
1063	our $CHLD_DELAY_W;	1398	our $CHLD_DELAY_W;
1064	our $PID_IDLE;
1065	our $WNOHANG;	1399	our $WNOHANG;
1066		1400
1067	sub _child_wait {	1401	sub _sigchld {
1068	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1402	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		1403	$_->($pid, $?)
1069	$_->($pid, $?) for (values %{ $PID_CB{$pid} || {} }),	1404	for values %{ $PID_CB{$pid} || {} },
1070	(values %{ $PID_CB{0} || {} });	1405	values %{ $PID_CB{0} || {} };
1071	}	1406	}
1072
1073	undef $PID_IDLE;
1074	}
1075
1076	sub _sigchld {
1077	# make sure we deliver these changes "synchronous" with the event loop.
1078	$CHLD_DELAY_W ||= AnyEvent->timer (after => 0, cb => sub {
1079	undef $CHLD_DELAY_W;
1080	&_child_wait;
1081	});
1082	}	1407	}
1083		1408
1084	sub child {	1409	sub child {
1085	my (undef, %arg) = @_;	1410	my (undef, %arg) = @_;
1086		1411
1087	defined (my $pid = $arg{pid} + 0)	1412	defined (my $pid = $arg{pid} + 0)
1088	or Carp::croak "required option 'pid' is missing";	1413	or Carp::croak "required option 'pid' is missing";
1089		1414
1090	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1415	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1091		1416
1092	unless ($WNOHANG) {	1417	# WNOHANG is almost cetrainly 1 everywhere
		1418	$WNOHANG ||= $^O =~ /^(?:openbsd|netbsd|linux|freebsd|cygwin|MSWin32)$/
		1419	? 1
1093	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;	1420	: eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } || 1;
1094	}
1095		1421
1096	unless ($CHLD_W) {	1422	unless ($CHLD_W) {
1097	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1423	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1098	# child could be a zombie already, so make at least one round	1424	# child could be a zombie already, so make at least one round
1099	&_sigchld;	1425	&_sigchld;
1100	}	1426	}
1101		1427
1102	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1428	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1103	}	1429	}
1104		1430
1105	sub AnyEvent::Base::Child::DESTROY {	1431	sub AnyEvent::Base::child::DESTROY {
1106	my ($pid, $cb) = @{$_[0]};	1432	my ($pid, $cb) = @{$_[0]};
1107		1433
1108	delete $PID_CB{$pid}{$cb};	1434	delete $PID_CB{$pid}{$cb};
1109	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1435	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1110		1436
1111	undef $CHLD_W unless keys %PID_CB;	1437	undef $CHLD_W unless keys %PID_CB;
1112	}	1438	}
1113		1439
		1440	# idle emulation is done by simply using a timer, regardless
		1441	# of whether the process is idle or not, and not letting
		1442	# the callback use more than 50% of the time.
		1443	sub idle {
		1444	my (undef, %arg) = @_;
		1445
		1446	my ($cb, $w, $rcb) = $arg{cb};
		1447
		1448	$rcb = sub {
		1449	if ($cb) {
		1450	$w = _time;
		1451	&$cb;
		1452	$w = _time - $w;
		1453
		1454	# never use more then 50% of the time for the idle watcher,
		1455	# within some limits
		1456	$w = 0.0001 if $w < 0.0001;
		1457	$w = 5 if $w > 5;
		1458
		1459	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1460	} else {
		1461	# clean up...
		1462	undef $w;
		1463	undef $rcb;
		1464	}
		1465	};
		1466
		1467	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1468
		1469	bless \\$cb, "AnyEvent::Base::idle"
		1470	}
		1471
		1472	sub AnyEvent::Base::idle::DESTROY {
		1473	undef $${$_[0]};
		1474	}
		1475
1114	package AnyEvent::CondVar;	1476	package AnyEvent::CondVar;
1115		1477
1116	our @ISA = AnyEvent::CondVar::Base::;	1478	our @ISA = AnyEvent::CondVar::Base::;
1117		1479
1118	package AnyEvent::CondVar::Base;	1480	package AnyEvent::CondVar::Base;
1119		1481
1120	use overload	1482	#use overload
1121	'&{}' => sub { my $self = shift; sub { $self->send (@_) } },	1483	# '&{}' => sub { my $self = shift; sub { $self->send (@_) } },
1122	fallback => 1;	1484	# fallback => 1;
		1485
		1486	# save 300+ kilobytes by dirtily hardcoding overloading
		1487	${"AnyEvent::CondVar::Base::OVERLOAD"}{dummy}++; # Register with magic by touching.
		1488	*{'AnyEvent::CondVar::Base::()'} = sub { }; # "Make it findable via fetchmethod."
		1489	*{'AnyEvent::CondVar::Base::(&{}'} = sub { my $self = shift; sub { $self->send (@_) } }; # &{}
		1490	${'AnyEvent::CondVar::Base::()'} = 1; # fallback
		1491
		1492	our $WAITING;
1123		1493
1124	sub _send {	1494	sub _send {
1125	# nop	1495	# nop
1126	}	1496	}
1127		1497
…		…
1140	sub ready {	1510	sub ready {
1141	$_[0]{_ae_sent}	1511	$_[0]{_ae_sent}
1142	}	1512	}
1143		1513
1144	sub _wait {	1514	sub _wait {
		1515	$WAITING
		1516	and !$_[0]{_ae_sent}
		1517	and Carp::croak "AnyEvent::CondVar: recursive blocking wait detected";
		1518
		1519	local $WAITING = 1;
1145	AnyEvent->one_event while !$_[0]{_ae_sent};	1520	AnyEvent->one_event while !$_[0]{_ae_sent};
1146	}	1521	}
1147		1522
1148	sub recv {	1523	sub recv {
1149	$_[0]->_wait;	1524	$_[0]->_wait;
…		…
1168	}	1543	}
1169		1544
1170	# undocumented/compatibility with pre-3.4	1545	# undocumented/compatibility with pre-3.4
1171	*broadcast = \&send;	1546	*broadcast = \&send;
1172	*wait = \&_wait;	1547	*wait = \&_wait;
		1548
		1549	=head1 ERROR AND EXCEPTION HANDLING
		1550
		1551	In general, AnyEvent does not do any error handling - it relies on the
		1552	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1553	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1554	checking of all AnyEvent methods, however, which is highly useful during
		1555	development.
		1556
		1557	As for exception handling (i.e. runtime errors and exceptions thrown while
		1558	executing a callback), this is not only highly event-loop specific, but
		1559	also not in any way wrapped by this module, as this is the job of the main
		1560	program.
		1561
		1562	The pure perl event loop simply re-throws the exception (usually
		1563	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1564	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1565	so on.
		1566
		1567	=head1 ENVIRONMENT VARIABLES
		1568
		1569	The following environment variables are used by this module or its
		1570	submodules.
		1571
		1572	Note that AnyEvent will remove I<all> environment variables starting with
		1573	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1574	enabled.
		1575
		1576	=over 4
		1577
		1578	=item C<PERL_ANYEVENT_VERBOSE>
		1579
		1580	By default, AnyEvent will be completely silent except in fatal
		1581	conditions. You can set this environment variable to make AnyEvent more
		1582	talkative.
		1583
		1584	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1585	conditions, such as not being able to load the event model specified by
		1586	C<PERL_ANYEVENT_MODEL>.
		1587
		1588	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1589	model it chooses.
		1590
		1591	When set to C<8> or higher, then AnyEvent will report extra information on
		1592	which optional modules it loads and how it implements certain features.
		1593
		1594	=item C<PERL_ANYEVENT_STRICT>
		1595
		1596	AnyEvent does not do much argument checking by default, as thorough
		1597	argument checking is very costly. Setting this variable to a true value
		1598	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1599	check the arguments passed to most method calls. If it finds any problems,
		1600	it will croak.
		1601
		1602	In other words, enables "strict" mode.
		1603
		1604	Unlike C<use strict> (or it's modern cousin, C<< use L<common::sense>
		1605	>>, it is definitely recommended to keep it off in production. Keeping
		1606	C<PERL_ANYEVENT_STRICT=1> in your environment while developing programs
		1607	can be very useful, however.
		1608
		1609	=item C<PERL_ANYEVENT_MODEL>
		1610
		1611	This can be used to specify the event model to be used by AnyEvent, before
		1612	auto detection and -probing kicks in. It must be a string consisting
		1613	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1614	and the resulting module name is loaded and if the load was successful,
		1615	used as event model. If it fails to load AnyEvent will proceed with
		1616	auto detection and -probing.
		1617
		1618	This functionality might change in future versions.
		1619
		1620	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1621	could start your program like this:
		1622
		1623	PERL_ANYEVENT_MODEL=Perl perl ...
		1624
		1625	=item C<PERL_ANYEVENT_PROTOCOLS>
		1626
		1627	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1628	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1629	of auto probing).
		1630
		1631	Must be set to a comma-separated list of protocols or address families,
		1632	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1633	used, and preference will be given to protocols mentioned earlier in the
		1634	list.
		1635
		1636	This variable can effectively be used for denial-of-service attacks
		1637	against local programs (e.g. when setuid), although the impact is likely
		1638	small, as the program has to handle conenction and other failures anyways.
		1639
		1640	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1641	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1642	- only support IPv4, never try to resolve or contact IPv6
		1643	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1644	IPv6, but prefer IPv6 over IPv4.
		1645
		1646	=item C<PERL_ANYEVENT_EDNS0>
		1647
		1648	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1649	for DNS. This extension is generally useful to reduce DNS traffic, but
		1650	some (broken) firewalls drop such DNS packets, which is why it is off by
		1651	default.
		1652
		1653	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1654	EDNS0 in its DNS requests.
		1655
		1656	=item C<PERL_ANYEVENT_MAX_FORKS>
		1657
		1658	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1659	will create in parallel.
		1660
		1661	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1662
		1663	The default value for the C<max_outstanding> parameter for the default DNS
		1664	resolver - this is the maximum number of parallel DNS requests that are
		1665	sent to the DNS server.
		1666
		1667	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1668
		1669	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1670	configuration) in the default resolver. When set to the empty string, no
		1671	default config will be used.
		1672
		1673	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1674
		1675	When neither C<ca_file> nor C<ca_path> was specified during
		1676	L<AnyEvent::TLS> context creation, and either of these environment
		1677	variables exist, they will be used to specify CA certificate locations
		1678	instead of a system-dependent default.
		1679
		1680	=item C<PERL_ANYEVENT_AVOID_GUARD> and C<PERL_ANYEVENT_AVOID_ASYNC_INTERRUPT>
		1681
		1682	When these are set to C<1>, then the respective modules are not
		1683	loaded. Mostly good for testing AnyEvent itself.
		1684
		1685	=back
1173		1686
1174	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1687	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1175		1688
1176	This is an advanced topic that you do not normally need to use AnyEvent in	1689	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	1690	a module. This section is only of use to event loop authors who want to
…		…
1211		1724
1212	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1725	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1213	condition variables: code blocking while waiting for a condition will	1726	condition variables: code blocking while waiting for a condition will
1214	C<die>. This still works with most modules/usages, and blocking calls must	1727	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.	1728	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		1729
1303	=head1 EXAMPLE PROGRAM	1730	=head1 EXAMPLE PROGRAM
1304		1731
1305	The following program uses an I/O watcher to read data from STDIN, a timer	1732	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	1733	to display a message once per second, and a condition variable to quit the
…		…
1500	watcher.	1927	watcher.
1501		1928
1502	=head3 Results	1929	=head3 Results
1503		1930
1504	name watchers bytes create invoke destroy comment	1931	name watchers bytes create invoke destroy comment
1505	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1932	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1506	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1933	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1507	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1934	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1508	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1935	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1509	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1936	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1510	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1937	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1938	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1939	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1511	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1940	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1512	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1941	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1513	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1942	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1514	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1943	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1515		1944
1516	=head3 Discussion	1945	=head3 Discussion
1517		1946
1518	The benchmark does I<not> measure scalability of the event loop very	1947	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)	1948	well. For example, a select-based event loop (such as the pure perl one)
…		…
1544	performance becomes really bad with lots of file descriptors (and few of	1973	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.	1974	them active), of course, but this was not subject of this benchmark.
1546		1975
1547	The C<Event> module has a relatively high setup and callback invocation	1976	The C<Event> module has a relatively high setup and callback invocation
1548	cost, but overall scores in on the third place.	1977	cost, but overall scores in on the third place.
		1978
		1979	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1980	when using its pure perl backend.
1549		1981
1550	C<Glib>'s memory usage is quite a bit higher, but it features a	1982	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	1983	faster callback invocation and overall ends up in the same class as
1552	C<Event>. However, Glib scales extremely badly, doubling the number of	1984	C<Event>. However, Glib scales extremely badly, doubling the number of
1553	watchers increases the processing time by more than a factor of four,	1985	watchers increases the processing time by more than a factor of four,
…		…
1631	it to another server. This includes deleting the old timeout and creating	2063	it to another server. This includes deleting the old timeout and creating
1632	a new one that moves the timeout into the future.	2064	a new one that moves the timeout into the future.
1633		2065
1634	=head3 Results	2066	=head3 Results
1635		2067
1636	name sockets create request	2068	name sockets create request
1637	EV 20000 69.01 11.16	2069	EV 20000 69.01 11.16
1638	Perl 20000 73.32 35.87	2070	Perl 20000 73.32 35.87
		2071	IOAsync 20000 157.00 98.14 epoll
		2072	IOAsync 20000 159.31 616.06 poll
1639	Event 20000 212.62 257.32	2073	Event 20000 212.62 257.32
1640	Glib 20000 651.16 1896.30	2074	Glib 20000 651.16 1896.30
1641	POE 20000 349.67 12317.24 uses POE::Loop::Event	2075	POE 20000 349.67 12317.24 uses POE::Loop::Event
1642		2076
1643	=head3 Discussion	2077	=head3 Discussion
1644		2078
1645	This benchmark I<does> measure scalability and overall performance of the	2079	This benchmark I<does> measure scalability and overall performance of the
1646	particular event loop.	2080	particular event loop.
…		…
1648	EV is again fastest. Since it is using epoll on my system, the setup time	2082	EV is again fastest. Since it is using epoll on my system, the setup time
1649	is relatively high, though.	2083	is relatively high, though.
1650		2084
1651	Perl surprisingly comes second. It is much faster than the C-based event	2085	Perl surprisingly comes second. It is much faster than the C-based event
1652	loops Event and Glib.	2086	loops Event and Glib.
		2087
		2088	IO::Async performs very well when using its epoll backend, and still quite
		2089	good compared to Glib when using its pure perl backend.
1653		2090
1654	Event suffers from high setup time as well (look at its code and you will	2091	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	2092	understand why). Callback invocation also has a high overhead compared to
1656	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	2093	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1657	uses select or poll in basically all documented configurations.	2094	uses select or poll in basically all documented configurations.
…		…
1720	=item * C-based event loops perform very well with small number of	2157	=item * C-based event loops perform very well with small number of
1721	watchers, as the management overhead dominates.	2158	watchers, as the management overhead dominates.
1722		2159
1723	=back	2160	=back
1724		2161
		2162	=head2 THE IO::Lambda BENCHMARK
		2163
		2164	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2165	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2166	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2167	shouldn't come as a surprise to anybody). As such, the benchmark is
		2168	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2169	very optimal. But how would AnyEvent compare when used without the extra
		2170	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2171
		2172	The benchmark itself creates an echo-server, and then, for 500 times,
		2173	connects to the echo server, sends a line, waits for the reply, and then
		2174	creates the next connection. This is a rather bad benchmark, as it doesn't
		2175	test the efficiency of the framework or much non-blocking I/O, but it is a
		2176	benchmark nevertheless.
		2177
		2178	name runtime
		2179	Lambda/select 0.330 sec
		2180	+ optimized 0.122 sec
		2181	Lambda/AnyEvent 0.327 sec
		2182	+ optimized 0.138 sec
		2183	Raw sockets/select 0.077 sec
		2184	POE/select, components 0.662 sec
		2185	POE/select, raw sockets 0.226 sec
		2186	POE/select, optimized 0.404 sec
		2187
		2188	AnyEvent/select/nb 0.085 sec
		2189	AnyEvent/EV/nb 0.068 sec
		2190	+state machine 0.134 sec
		2191
		2192	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2193	benchmarks actually make blocking connects and use 100% blocking I/O,
		2194	defeating the purpose of an event-based solution. All of the newly
		2195	written AnyEvent benchmarks use 100% non-blocking connects (using
		2196	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2197	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2198	generally require a lot more bookkeeping and event handling than blocking
		2199	connects (which involve a single syscall only).
		2200
		2201	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2202	offers similar expressive power as POE and IO::Lambda, using conventional
		2203	Perl syntax. This means that both the echo server and the client are 100%
		2204	non-blocking, further placing it at a disadvantage.
		2205
		2206	As you can see, the AnyEvent + EV combination even beats the
		2207	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2208	backend easily beats IO::Lambda and POE.
		2209
		2210	And even the 100% non-blocking version written using the high-level (and
		2211	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2212	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2213	in a non-blocking way.
		2214
		2215	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2216	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2217	part of the IO::lambda distribution and were used without any changes.
		2218
		2219
		2220	=head1 SIGNALS
		2221
		2222	AnyEvent currently installs handlers for these signals:
		2223
		2224	=over 4
		2225
		2226	=item SIGCHLD
		2227
		2228	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2229	emulation for event loops that do not support them natively. Also, some
		2230	event loops install a similar handler.
		2231
		2232	Additionally, when AnyEvent is loaded and SIGCHLD is set to IGNORE, then
		2233	AnyEvent will reset it to default, to avoid losing child exit statuses.
		2234
		2235	=item SIGPIPE
		2236
		2237	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2238	when AnyEvent gets loaded.
		2239
		2240	The rationale for this is that AnyEvent users usually do not really depend
		2241	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2242	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2243	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2244	some random socket.
		2245
		2246	The rationale for installing a no-op handler as opposed to ignoring it is
		2247	that this way, the handler will be restored to defaults on exec.
		2248
		2249	Feel free to install your own handler, or reset it to defaults.
		2250
		2251	=back
		2252
		2253	=cut
		2254
		2255	undef $SIG{CHLD}
		2256	if $SIG{CHLD} eq 'IGNORE';
		2257
		2258	$SIG{PIPE} = sub { }
		2259	unless defined $SIG{PIPE};
		2260
		2261	=head1 RECOMMENDED/OPTIONAL MODULES
		2262
		2263	One of AnyEvent's main goals is to be 100% Pure-Perl(tm): only perl (and
		2264	it's built-in modules) are required to use it.
		2265
		2266	That does not mean that AnyEvent won't take advantage of some additional
		2267	modules if they are installed.
		2268
		2269	This section epxlains which additional modules will be used, and how they
		2270	affect AnyEvent's operetion.
		2271
		2272	=over 4
		2273
		2274	=item L<Async::Interrupt>
		2275
		2276	This slightly arcane module is used to implement fast signal handling: To
		2277	my knowledge, there is no way to do completely race-free and quick
		2278	signal handling in pure perl. To ensure that signals still get
		2279	delivered, AnyEvent will start an interval timer to wake up perl (and
		2280	catch the signals) with some delay (default is 10 seconds, look for
		2281	C<$AnyEvent::MAX_SIGNAL_LATENCY>).
		2282
		2283	If this module is available, then it will be used to implement signal
		2284	catching, which means that signals will not be delayed, and the event loop
		2285	will not be interrupted regularly, which is more efficient (And good for
		2286	battery life on laptops).
		2287
		2288	This affects not just the pure-perl event loop, but also other event loops
		2289	that have no signal handling on their own (e.g. Glib, Tk, Qt).
		2290
		2291	Some event loops (POE, Event, Event::Lib) offer signal watchers natively,
		2292	and either employ their own workarounds (POE) or use AnyEvent's workaround
		2293	(using C<$AnyEvent::MAX_SIGNAL_LATENCY>). Installing L<Async::Interrupt>
		2294	does nothing for those backends.
		2295
		2296	=item L<EV>
		2297
		2298	This module isn't really "optional", as it is simply one of the backend
		2299	event loops that AnyEvent can use. However, it is simply the best event
		2300	loop available in terms of features, speed and stability: It supports
		2301	the AnyEvent API optimally, implements all the watcher types in XS, does
		2302	automatic timer adjustments even when no monotonic clock is available,
		2303	can take avdantage of advanced kernel interfaces such as C<epoll> and
		2304	C<kqueue>, and is the fastest backend I<by far>. You can even embed
		2305	L<Glib>/L<Gtk2> in it (or vice versa, see L<EV::Glib> and L<Glib::EV>).
		2306
		2307	=item L<Guard>
		2308
		2309	The guard module, when used, will be used to implement
		2310	C<AnyEvent::Util::guard>. This speeds up guards considerably (and uses a
		2311	lot less memory), but otherwise doesn't affect guard operation much. It is
		2312	purely used for performance.
		2313
		2314	=item L<JSON> and L<JSON::XS>
		2315
		2316	This module is required when you want to read or write JSON data via
		2317	L<AnyEvent::Handle>. It is also written in pure-perl, but can take
		2318	advantage of the ulta-high-speed L<JSON::XS> module when it is installed.
		2319
		2320	In fact, L<AnyEvent::Handle> will use L<JSON::XS> by default if it is
		2321	installed.
		2322
		2323	=item L<Net::SSLeay>
		2324
		2325	Implementing TLS/SSL in Perl is certainly interesting, but not very
		2326	worthwhile: If this module is installed, then L<AnyEvent::Handle> (with
		2327	the help of L<AnyEvent::TLS>), gains the ability to do TLS/SSL.
		2328
		2329	=item L<Time::HiRes>
		2330
		2331	This module is part of perl since release 5.008. It will be used when the
		2332	chosen event library does not come with a timing source on it's own. The
		2333	pure-perl event loop (L<AnyEvent::Impl::Perl>) will additionally use it to
		2334	try to use a monotonic clock for timing stability.
		2335
		2336	=back
		2337
1725		2338
1726	=head1 FORK	2339	=head1 FORK
1727		2340
1728	Most event libraries are not fork-safe. The ones who are usually are	2341	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>	2342	because they rely on inefficient but fork-safe C<select> or C<poll>
1730	calls. Only L<EV> is fully fork-aware.	2343	calls. Only L<EV> is fully fork-aware.
1731		2344
1732	If you have to fork, you must either do so I<before> creating your first	2345	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.	2346	watcher OR you must not use AnyEvent at all in the child OR you must do
		2347	something completely out of the scope of AnyEvent.
1734		2348
1735		2349
1736	=head1 SECURITY CONSIDERATIONS	2350	=head1 SECURITY CONSIDERATIONS
1737		2351
1738	AnyEvent can be forced to load any event model via	2352	AnyEvent can be forced to load any event model via
…		…
1750	use AnyEvent;	2364	use AnyEvent;
1751		2365
1752	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2366	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	2367	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	2368	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1755	$ENV{PERL_ANYEGENT_STRICT}.	2369	$ENV{PERL_ANYEVENT_STRICT}.
		2370
		2371	Note that AnyEvent will remove I<all> environment variables starting with
		2372	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2373	enabled.
1756		2374
1757		2375
1758	=head1 BUGS	2376	=head1 BUGS
1759		2377
1760	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2378	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	2379	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	2380	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	2381	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1764	pronounced).	2382	pronounced).
1765		2383
1766		2384
1767	=head1 SEE ALSO	2385	=head1 SEE ALSO
1768		2386
…		…
1772	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2390	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1773		2391
1774	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2392	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1775	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2393	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1776	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2394	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1777	L<AnyEvent::Impl::POE>.	2395	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1778		2396
1779	Non-blocking file handles, sockets, TCP clients and	2397	Non-blocking file handles, sockets, TCP clients and
1780	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2398	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1781		2399
1782	Asynchronous DNS: L<AnyEvent::DNS>.	2400	Asynchronous DNS: L<AnyEvent::DNS>.
1783		2401
1784	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2402	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2403	L<Coro::Event>,
1785		2404
1786	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2405	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2406	L<AnyEvent::HTTP>.
1787		2407
1788		2408
1789	=head1 AUTHOR	2409	=head1 AUTHOR
1790		2410
1791	Marc Lehmann <schmorp@schmorp.de>	2411	Marc Lehmann <schmorp@schmorp.de>

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