[ViewVC] Diff of: cvs/AnyEvent/lib/AnyEvent.pm

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.173 by root, Mon Jul 21 03:47:22 2008 UTC vs.
Revision 1.234 by root, Thu Jul 9 08:31:16 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
…		…
340	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
341		376
342	You can also watch on a child process exit and catch its exit status.	377	You can also watch on a child process exit and catch its exit status.
343		378
344	The child process is specified by the C<pid> argument (if set to C<0>, it	379	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	380	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	381	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	382	any trace events (stopped/continued).
348	and exit status (as returned by waitpid), so unlike other watcher types,	383
349	you I<can> rely on child watcher callback arguments.	384	The callback will be called with the pid and exit status (as returned by
		385	waitpid), so unlike other watcher types, you I<can> rely on child watcher
		386	callback arguments.
		387
		388	This watcher type works by installing a signal handler for C<SIGCHLD>,
		389	and since it cannot be shared, nothing else should use SIGCHLD or reap
		390	random child processes (waiting for specific child processes, e.g. inside
		391	C<system>, is just fine).
350		392
351	There is a slight catch to child watchers, however: you usually start them	393	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	394	I<after> the child process was created, and this means the process could
353	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
354		396
355	Not all event models handle this correctly (POE doesn't), but even for	397	Not all event models handle this correctly (neither POE nor IO::Async do,
		398	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	399	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).	400	the process exits (i.e. before you fork in the first place). AnyEvent's
		401	pure perl event loop handles all cases correctly regardless of when you
		402	start the watcher.
358		403
359	This means you cannot create a child watcher as the very first thing in an	404	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	405	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>).	406	watcher before you C<fork> the child (alternatively, you can call
		407	C<AnyEvent::detect>).
362		408
363	Example: fork a process and wait for it	409	Example: fork a process and wait for it
364		410
365	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
366		412
…		…
376	);	422	);
377		423
378	# do something else, then wait for process exit	424	# do something else, then wait for process exit
379	$done->recv;	425	$done->recv;
380		426
		427	=head2 IDLE WATCHERS
		428
		429	Sometimes there is a need to do something, but it is not so important
		430	to do it instantly, but only when there is nothing better to do. This
		431	"nothing better to do" is usually defined to be "no other events need
		432	attention by the event loop".
		433
		434	Idle watchers ideally get invoked when the event loop has nothing
		435	better to do, just before it would block the process to wait for new
		436	events. Instead of blocking, the idle watcher is invoked.
		437
		438	Most event loops unfortunately do not really support idle watchers (only
		439	EV, Event and Glib do it in a usable fashion) - for the rest, AnyEvent
		440	will simply call the callback "from time to time".
		441
		442	Example: read lines from STDIN, but only process them when the
		443	program is otherwise idle:
		444
		445	my @lines; # read data
		446	my $idle_w;
		447	my $io_w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		448	push @lines, scalar <STDIN>;
		449
		450	# start an idle watcher, if not already done
		451	$idle_w \|\|= AnyEvent->idle (cb => sub {
		452	# handle only one line, when there are lines left
		453	if (my $line = shift @lines) {
		454	print "handled when idle: $line";
		455	} else {
		456	# otherwise disable the idle watcher again
		457	undef $idle_w;
		458	}
		459	});
		460	});
		461
381	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
382		463
383	If you are familiar with some event loops you will know that all of them	464	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	465	require you to run some blocking "loop", "run" or similar function that
385	will actively watch for new events and call your callbacks.	466	will actively watch for new events and call your callbacks.
…		…
389		470
390	The instrument to do that is called a "condition variable", so called	471	The instrument to do that is called a "condition variable", so called
391	because they represent a condition that must become true.	472	because they represent a condition that must become true.
392		473
393	Condition variables can be created by calling the C<< AnyEvent->condvar	474	Condition variables can be created by calling the C<< AnyEvent->condvar
394
395	>> method, usually without arguments. The only argument pair allowed is	475	>> method, usually without arguments. The only argument pair allowed is
396		476
397	C<cb>, which specifies a callback to be called when the condition variable	477	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	478	becomes true, with the condition variable as the first argument (but not
399	the results).	479	the results).
…		…
519		599
520	=item $cv->begin ([group callback])	600	=item $cv->begin ([group callback])
521		601
522	=item $cv->end	602	=item $cv->end
523		603
524	These two methods are EXPERIMENTAL and MIGHT CHANGE.
525
526	These two methods can be used to combine many transactions/events into	604	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	605	one. For example, a function that pings many hosts in parallel might want
528	to use a condition variable for the whole process.	606	to use a condition variable for the whole process.
529		607
530	Every call to C<< ->begin >> will increment a counter, and every call to	608	Every call to C<< ->begin >> will increment a counter, and every call to
531	C<< ->end >> will decrement it. If the counter reaches C<0> in C<< ->end	609	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	610	>>, 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	611	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.	612	callback was set, C<send> will be called without any arguments.
535		613
536	Let's clarify this with the ping example:	614	You can think of C<< $cv->send >> giving you an OR condition (one call
		615	sends), while C<< $cv->begin >> and C<< $cv->end >> giving you an AND
		616	condition (all C<begin> calls must be C<end>'ed before the condvar sends).
		617
		618	Let's start with a simple example: you have two I/O watchers (for example,
		619	STDOUT and STDERR for a program), and you want to wait for both streams to
		620	close before activating a condvar:
		621
		622	my $cv = AnyEvent->condvar;
		623
		624	$cv->begin; # first watcher
		625	my $w1 = AnyEvent->io (fh => $fh1, cb => sub {
		626	defined sysread $fh1, my $buf, 4096
		627	or $cv->end;
		628	});
		629
		630	$cv->begin; # second watcher
		631	my $w2 = AnyEvent->io (fh => $fh2, cb => sub {
		632	defined sysread $fh2, my $buf, 4096
		633	or $cv->end;
		634	});
		635
		636	$cv->recv;
		637
		638	This works because for every event source (EOF on file handle), there is
		639	one call to C<begin>, so the condvar waits for all calls to C<end> before
		640	sending.
		641
		642	The ping example mentioned above is slightly more complicated, as the
		643	there are results to be passwd back, and the number of tasks that are
		644	begung can potentially be zero:
537		645
538	my $cv = AnyEvent->condvar;	646	my $cv = AnyEvent->condvar;
539		647
540	my %result;	648	my %result;
541	$cv->begin (sub { $cv->send (\%result) });	649	$cv->begin (sub { $cv->send (\%result) });
…		…
561	loop, which serves two important purposes: first, it sets the callback	669	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	670	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	671	C<send> is called even when C<no> hosts are being pinged (the loop
564	doesn't execute once).	672	doesn't execute once).
565		673
566	This is the general pattern when you "fan out" into multiple subrequests:	674	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>	675	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	676	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>.	677	subrequest you start, call C<begin> and for each subrequest you finish,
		678	call C<end>.
570		679
571	=back	680	=back
572		681
573	=head3 METHODS FOR CONSUMERS	682	=head3 METHODS FOR CONSUMERS
574		683
…		…
631	variable itself. Calling C<recv> inside the callback or at any later time	740	variable itself. Calling C<recv> inside the callback or at any later time
632	is guaranteed not to block.	741	is guaranteed not to block.
633		742
634	=back	743	=back
635		744
		745	=head1 SUPPORTED EVENT LOOPS/BACKENDS
		746
		747	The available backend classes are (every class has its own manpage):
		748
		749	=over 4
		750
		751	=item Backends that are autoprobed when no other event loop can be found.
		752
		753	EV is the preferred backend when no other event loop seems to be in
		754	use. If EV is not installed, then AnyEvent will try Event, and, failing
		755	that, will fall back to its own pure-perl implementation, which is
		756	available everywhere as it comes with AnyEvent itself.
		757
		758	AnyEvent::Impl::EV based on EV (interface to libev, best choice).
		759	AnyEvent::Impl::Event based on Event, very stable, few glitches.
		760	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
		761
		762	=item Backends that are transparently being picked up when they are used.
		763
		764	These will be used when they are currently loaded when the first watcher
		765	is created, in which case it is assumed that the application is using
		766	them. This means that AnyEvent will automatically pick the right backend
		767	when the main program loads an event module before anything starts to
		768	create watchers. Nothing special needs to be done by the main program.
		769
		770	AnyEvent::Impl::Glib based on Glib, slow but very stable.
		771	AnyEvent::Impl::Tk based on Tk, very broken.
		772	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		773	AnyEvent::Impl::POE based on POE, very slow, some limitations.
		774
		775	=item Backends with special needs.
		776
		777	Qt requires the Qt::Application to be instantiated first, but will
		778	otherwise be picked up automatically. As long as the main program
		779	instantiates the application before any AnyEvent watchers are created,
		780	everything should just work.
		781
		782	AnyEvent::Impl::Qt based on Qt.
		783
		784	Support for IO::Async can only be partial, as it is too broken and
		785	architecturally limited to even support the AnyEvent API. It also
		786	is the only event loop that needs the loop to be set explicitly, so
		787	it can only be used by a main program knowing about AnyEvent. See
		788	L<AnyEvent::Impl::Async> for the gory details.
		789
		790	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed.
		791
		792	=item Event loops that are indirectly supported via other backends.
		793
		794	Some event loops can be supported via other modules:
		795
		796	There is no direct support for WxWidgets (L<Wx>) or L<Prima>.
		797
		798	B<WxWidgets> has no support for watching file handles. However, you can
		799	use WxWidgets through the POE adaptor, as POE has a Wx backend that simply
		800	polls 20 times per second, which was considered to be too horrible to even
		801	consider for AnyEvent.
		802
		803	B<Prima> is not supported as nobody seems to be using it, but it has a POE
		804	backend, so it can be supported through POE.
		805
		806	AnyEvent knows about both L<Prima> and L<Wx>, however, and will try to
		807	load L<POE> when detecting them, in the hope that POE will pick them up,
		808	in which case everything will be automatic.
		809
		810	=back
		811
636	=head1 GLOBAL VARIABLES AND FUNCTIONS	812	=head1 GLOBAL VARIABLES AND FUNCTIONS
637		813
		814	These are not normally required to use AnyEvent, but can be useful to
		815	write AnyEvent extension modules.
		816
638	=over 4	817	=over 4
639		818
640	=item $AnyEvent::MODEL	819	=item $AnyEvent::MODEL
641		820
642	Contains C<undef> until the first watcher is being created. Then it	821	Contains C<undef> until the first watcher is being created, before the
		822	backend has been autodetected.
		823
643	contains the event model that is being used, which is the name of the	824	Afterwards it contains the event model that is being used, which is the
644	Perl class implementing the model. This class is usually one of the	825	name of the Perl class implementing the model. This class is usually one
645	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case	826	of the C<AnyEvent::Impl:xxx> modules, but can be any other class in the
646	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).	827	case AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode> it
647		828	will be C<urxvt::anyevent>).
648	The known classes so far are:
649
650	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
651	AnyEvent::Impl::Event based on Event, second best choice.
652	AnyEvent::Impl::Perl pure-perl implementation, fast and portable.
653	AnyEvent::Impl::Glib based on Glib, third-best choice.
654	AnyEvent::Impl::Tk based on Tk, very bad choice.
655	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
656	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
657	AnyEvent::Impl::POE based on POE, not generic enough for full support.
658
659	There is no support for WxWidgets, as WxWidgets has no support for
660	watching file handles. However, you can use WxWidgets through the
661	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
662	second, which was considered to be too horrible to even consider for
663	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
664	it's adaptor.
665
666	AnyEvent knows about L<Prima> and L<Wx> and will try to use L<POE> when
667	autodetecting them.
668		829
669	=item AnyEvent::detect	830	=item AnyEvent::detect
670		831
671	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model	832	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
672	if necessary. You should only call this function right before you would	833	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	834	have created an AnyEvent watcher anyway, that is, as late as possible at
674	runtime.	835	runtime, and not e.g. while initialising of your module.
		836
		837	If you need to do some initialisation before AnyEvent watchers are
		838	created, use C<post_detect>.
675		839
676	=item $guard = AnyEvent::post_detect { BLOCK }	840	=item $guard = AnyEvent::post_detect { BLOCK }
677		841
678	Arranges for the code block to be executed as soon as the event model is	842	Arranges for the code block to be executed as soon as the event model is
679	autodetected (or immediately if this has already happened).	843	autodetected (or immediately if this has already happened).
		844
		845	The block will be executed I<after> the actual backend has been detected
		846	(C<$AnyEvent::MODEL> is set), but I<before> any watchers have been
		847	created, so it is possible to e.g. patch C<@AnyEvent::ISA> or do
		848	other initialisations - see the sources of L<AnyEvent::Strict> or
		849	L<AnyEvent::AIO> to see how this is used.
		850
		851	The most common usage is to create some global watchers, without forcing
		852	event module detection too early, for example, L<AnyEvent::AIO> creates
		853	and installs the global L<IO::AIO> watcher in a C<post_detect> block to
		854	avoid autodetecting the event module at load time.
680		855
681	If called in scalar or list context, then it creates and returns an object	856	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	857	that automatically removes the callback again when it is destroyed. See
683	L<Coro::BDB> for a case where this is useful.	858	L<Coro::BDB> for a case where this is useful.
684		859
…		…
687	If there are any code references in this array (you can C<push> to it	862	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	863	before or after loading AnyEvent), then they will called directly after
689	the event loop has been chosen.	864	the event loop has been chosen.
690		865
691	You should check C<$AnyEvent::MODEL> before adding to this array, though:	866	You should check C<$AnyEvent::MODEL> before adding to this array, though:
692	if it contains a true value then the event loop has already been detected,	867	if it is defined then the event loop has already been detected, and the
693	and the array will be ignored.	868	array will be ignored.
694		869
695	Best use C<AnyEvent::post_detect { BLOCK }> instead.	870	Best use C<AnyEvent::post_detect { BLOCK }> when your application allows
		871	it,as it takes care of these details.
		872
		873	This variable is mainly useful for modules that can do something useful
		874	when AnyEvent is used and thus want to know when it is initialised, but do
		875	not need to even load it by default. This array provides the means to hook
		876	into AnyEvent passively, without loading it.
696		877
697	=back	878	=back
698		879
699	=head1 WHAT TO DO IN A MODULE	880	=head1 WHAT TO DO IN A MODULE
700		881
…		…
755		936
756		937
757	=head1 OTHER MODULES	938	=head1 OTHER MODULES
758		939
759	The following is a non-exhaustive list of additional modules that use	940	The following is a non-exhaustive list of additional modules that use
760	AnyEvent and can therefore be mixed easily with other AnyEvent modules	941	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	942	modules and other event loops in the same program. Some of the modules
762	available via CPAN.	943	come with AnyEvent, most are available via CPAN.
763		944
764	=over 4	945	=over 4
765		946
766	=item L<AnyEvent::Util>	947	=item L<AnyEvent::Util>
767		948
…		…
776		957
777	=item L<AnyEvent::Handle>	958	=item L<AnyEvent::Handle>
778		959
779	Provide read and write buffers, manages watchers for reads and writes,	960	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	961	supports raw and formatted I/O, I/O queued and fully transparent and
781	non-blocking SSL/TLS.	962	non-blocking SSL/TLS (via L<AnyEvent::TLS>.
782		963
783	=item L<AnyEvent::DNS>	964	=item L<AnyEvent::DNS>
784		965
785	Provides rich asynchronous DNS resolver capabilities.	966	Provides rich asynchronous DNS resolver capabilities.
786		967
…		…
814		995
815	=item L<AnyEvent::GPSD>	996	=item L<AnyEvent::GPSD>
816		997
817	A non-blocking interface to gpsd, a daemon delivering GPS information.	998	A non-blocking interface to gpsd, a daemon delivering GPS information.
818		999
		1000	=item L<AnyEvent::IRC>
		1001
		1002	AnyEvent based IRC client module family (replacing the older Net::IRC3).
		1003
		1004	=item L<AnyEvent::XMPP>
		1005
		1006	AnyEvent based XMPP (Jabber protocol) module family (replacing the older
		1007	Net::XMPP2>.
		1008
819	=item L<AnyEvent::IGS>	1009	=item L<AnyEvent::IGS>
820		1010
821	A non-blocking interface to the Internet Go Server protocol (used by	1011	A non-blocking interface to the Internet Go Server protocol (used by
822	L<App::IGS>).	1012	L<App::IGS>).
823		1013
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>	1014	=item L<Net::FCP>
833		1015
834	AnyEvent-based implementation of the Freenet Client Protocol, birthplace	1016	AnyEvent-based implementation of the Freenet Client Protocol, birthplace
835	of AnyEvent.	1017	of AnyEvent.
836		1018
…		…
840		1022
841	=item L<Coro>	1023	=item L<Coro>
842		1024
843	Has special support for AnyEvent via L<Coro::AnyEvent>.	1025	Has special support for AnyEvent via L<Coro::AnyEvent>.
844		1026
845	=item L<IO::Lambda>
846
847	The lambda approach to I/O - don't ask, look there. Can use AnyEvent.
848
849	=back	1027	=back
850		1028
851	=cut	1029	=cut
852		1030
853	package AnyEvent;	1031	package AnyEvent;
854		1032
855	no warnings;	1033	no warnings;
856	use strict;	1034	use strict qw(vars subs);
857		1035
858	use Carp;	1036	use Carp;
859		1037
860	our $VERSION = 4.22;	1038	our $VERSION = 4.81;
861	our $MODEL;	1039	our $MODEL;
862		1040
863	our $AUTOLOAD;	1041	our $AUTOLOAD;
864	our @ISA;	1042	our @ISA;
865		1043
866	our @REGISTRY;	1044	our @REGISTRY;
867		1045
868	our $WIN32;	1046	our $WIN32;
869		1047
870	BEGIN {	1048	BEGIN {
871	my $win32 = ! ! ($^O =~ /mswin32/i);	1049	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
872	eval "sub WIN32(){ $win32 }";	1050	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		1051
		1052	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		1053	if ${^TAINT};
873	}	1054	}
874		1055
875	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	1056	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
876		1057
877	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred	1058	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
…		…
888	[Event:: => AnyEvent::Impl::Event::],	1069	[Event:: => AnyEvent::Impl::Event::],
889	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],	1070	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
890	# everything below here will not be autoprobed	1071	# everything below here will not be autoprobed
891	# as the pureperl backend should work everywhere	1072	# as the pureperl backend should work everywhere
892	# and is usually faster	1073	# and is usually faster
893	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
894	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers	1074	[Glib:: => AnyEvent::Impl::Glib::], # becomes extremely slow with many watchers
895	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1075	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		1076	[Tk:: => AnyEvent::Impl::Tk::], # crashes with many handles
		1077	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
896	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1078	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
897	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
898	[Wx:: => AnyEvent::Impl::POE::],	1079	[Wx:: => AnyEvent::Impl::POE::],
899	[Prima:: => AnyEvent::Impl::POE::],	1080	[Prima:: => AnyEvent::Impl::POE::],
		1081	# IO::Async is just too broken - we would need workarounds for its
		1082	# byzantine signal and broken child handling, among others.
		1083	# IO::Async is rather hard to detect, as it doesn't have any
		1084	# obvious default class.
		1085	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1086	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1087	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
900	);	1088	);
901		1089
902	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1090	our %method = map +($_ => 1),
		1091	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
903		1092
904	our @post_detect;	1093	our @post_detect;
905		1094
906	sub post_detect(&) {	1095	sub post_detect(&) {
907	my ($cb) = @_;	1096	my ($cb) = @_;
…		…
912	1	1101	1
913	} else {	1102	} else {
914	push @post_detect, $cb;	1103	push @post_detect, $cb;
915		1104
916	defined wantarray	1105	defined wantarray
917	? bless \$cb, "AnyEvent::Util::PostDetect"	1106	? bless \$cb, "AnyEvent::Util::postdetect"
918	: ()	1107	: ()
919	}	1108	}
920	}	1109	}
921		1110
922	sub AnyEvent::Util::PostDetect::DESTROY {	1111	sub AnyEvent::Util::postdetect::DESTROY {
923	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1112	@post_detect = grep $_ != ${$_[0]}, @post_detect;
924	}	1113	}
925		1114
926	sub detect() {	1115	sub detect() {
927	unless ($MODEL) {	1116	unless ($MODEL) {
…		…
964	last;	1153	last;
965	}	1154	}
966	}	1155	}
967		1156
968	$MODEL	1157	$MODEL
969	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1158	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
970	}	1159	}
971	}	1160	}
972		1161
973	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1162	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
974		1163
…		…
995	}	1184	}
996		1185
997	# utility function to dup a filehandle. this is used by many backends	1186	# utility function to dup a filehandle. this is used by many backends
998	# to support binding more than one watcher per filehandle (they usually	1187	# 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).	1188	# allow only one watcher per fd, so we dup it to get a different one).
1000	sub _dupfh($$$$) {	1189	sub _dupfh($$;$$) {
1001	my ($poll, $fh, $r, $w) = @_;	1190	my ($poll, $fh, $r, $w) = @_;
1002		1191
1003	require Fcntl;
1004
1005	# cygwin requires the fh mode to be matching, unix doesn't	1192	# cygwin requires the fh mode to be matching, unix doesn't
1006	my ($rw, $mode) = $poll eq "r" ? ($r, "<")	1193	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		1194
1010	open my $fh2, "$mode&" . fileno $fh	1195	open my $fh2, "$mode&", $fh
1011	or die "cannot dup() filehandle: $!";	1196	or die "AnyEvent->io: cannot dup() filehandle in mode '$poll': $!,";
1012		1197
1013	# we assume CLOEXEC is already set by perl in all important cases	1198	# we assume CLOEXEC is already set by perl in all important cases
1014		1199
1015	($fh2, $rw)	1200	($fh2, $rw)
1016	}	1201	}
1017		1202
1018	package AnyEvent::Base;	1203	package AnyEvent::Base;
1019		1204
1020	# default implementation for now and time	1205	# default implementations for many methods
1021		1206
1022	use Time::HiRes ();	1207	BEGIN {
		1208	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1209	*_time = \&Time::HiRes::time;
		1210	# if (eval "use POSIX (); (POSIX::times())...
		1211	} else {
		1212	*_time = sub { time }; # epic fail
		1213	}
		1214	}
1023		1215
1024	sub time { Time::HiRes::time }	1216	sub time { _time }
1025	sub now { Time::HiRes::time }	1217	sub now { _time }
		1218	sub now_update { }
1026		1219
1027	# default implementation for ->condvar	1220	# default implementation for ->condvar
1028		1221
1029	sub condvar {	1222	sub condvar {
1030	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1223	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
1031	}	1224	}
1032		1225
1033	# default implementation for ->signal	1226	# default implementation for ->signal
1034		1227
1035	our %SIG_CB;	1228	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1229
		1230	sub _signal_exec {
		1231	sysread $SIGPIPE_R, my $dummy, 4;
		1232
		1233	while (%SIG_EV) {
		1234	for (keys %SIG_EV) {
		1235	delete $SIG_EV{$_};
		1236	$_->() for values %{ $SIG_CB{$_} \|\| {} };
		1237	}
		1238	}
		1239	}
1036		1240
1037	sub signal {	1241	sub signal {
1038	my (undef, %arg) = @_;	1242	my (undef, %arg) = @_;
1039		1243
		1244	unless ($SIGPIPE_R) {
		1245	require Fcntl;
		1246
		1247	if (AnyEvent::WIN32) {
		1248	require AnyEvent::Util;
		1249
		1250	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1251	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1252	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1253	} else {
		1254	pipe $SIGPIPE_R, $SIGPIPE_W;
		1255	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1256	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1257
		1258	# not strictly required, as $^F is normally 2, but let's make sure...
		1259	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1260	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1261	}
		1262
		1263	$SIGPIPE_R
		1264	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1265
		1266	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1267	}
		1268
1040	my $signal = uc $arg{signal}	1269	my $signal = uc $arg{signal}
1041	or Carp::croak "required option 'signal' is missing";	1270	or Carp::croak "required option 'signal' is missing";
1042		1271
1043	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1272	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
1044	$SIG{$signal} \|\|= sub {	1273	$SIG{$signal} \|\|= sub {
1045	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1274	local $!;
		1275	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1276	undef $SIG_EV{$signal};
1046	};	1277	};
1047		1278
1048	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1279	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
1049	}	1280	}
1050		1281
1051	sub AnyEvent::Base::Signal::DESTROY {	1282	sub AnyEvent::Base::signal::DESTROY {
1052	my ($signal, $cb) = @{$_[0]};	1283	my ($signal, $cb) = @{$_[0]};
1053		1284
1054	delete $SIG_CB{$signal}{$cb};	1285	delete $SIG_CB{$signal}{$cb};
1055		1286
		1287	# delete doesn't work with older perls - they then
		1288	# print weird messages, or just unconditionally exit
		1289	# instead of getting the default action.
1056	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1290	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1057	}	1291	}
1058		1292
1059	# default implementation for ->child	1293	# default implementation for ->child
1060		1294
1061	our %PID_CB;	1295	our %PID_CB;
1062	our $CHLD_W;	1296	our $CHLD_W;
1063	our $CHLD_DELAY_W;	1297	our $CHLD_DELAY_W;
1064	our $PID_IDLE;
1065	our $WNOHANG;	1298	our $WNOHANG;
1066		1299
1067	sub _child_wait {	1300	sub _sigchld {
1068	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1301	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
1069	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),	1302	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
1070	(values %{ $PID_CB{0} \|\| {} });	1303	(values %{ $PID_CB{0} \|\| {} });
1071	}	1304	}
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	}	1305	}
1083		1306
1084	sub child {	1307	sub child {
1085	my (undef, %arg) = @_;	1308	my (undef, %arg) = @_;
1086		1309
1087	defined (my $pid = $arg{pid} + 0)	1310	defined (my $pid = $arg{pid} + 0)
1088	or Carp::croak "required option 'pid' is missing";	1311	or Carp::croak "required option 'pid' is missing";
1089		1312
1090	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1313	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1091		1314
1092	unless ($WNOHANG) {
1093	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;	1315	$WNOHANG \|\|= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
1094	}
1095		1316
1096	unless ($CHLD_W) {	1317	unless ($CHLD_W) {
1097	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1318	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1098	# child could be a zombie already, so make at least one round	1319	# child could be a zombie already, so make at least one round
1099	&_sigchld;	1320	&_sigchld;
1100	}	1321	}
1101		1322
1102	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1323	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1103	}	1324	}
1104		1325
1105	sub AnyEvent::Base::Child::DESTROY {	1326	sub AnyEvent::Base::child::DESTROY {
1106	my ($pid, $cb) = @{$_[0]};	1327	my ($pid, $cb) = @{$_[0]};
1107		1328
1108	delete $PID_CB{$pid}{$cb};	1329	delete $PID_CB{$pid}{$cb};
1109	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1330	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1110		1331
1111	undef $CHLD_W unless keys %PID_CB;	1332	undef $CHLD_W unless keys %PID_CB;
		1333	}
		1334
		1335	# idle emulation is done by simply using a timer, regardless
		1336	# of whether the process is idle or not, and not letting
		1337	# the callback use more than 50% of the time.
		1338	sub idle {
		1339	my (undef, %arg) = @_;
		1340
		1341	my ($cb, $w, $rcb) = $arg{cb};
		1342
		1343	$rcb = sub {
		1344	if ($cb) {
		1345	$w = _time;
		1346	&$cb;
		1347	$w = _time - $w;
		1348
		1349	# never use more then 50% of the time for the idle watcher,
		1350	# within some limits
		1351	$w = 0.0001 if $w < 0.0001;
		1352	$w = 5 if $w > 5;
		1353
		1354	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1355	} else {
		1356	# clean up...
		1357	undef $w;
		1358	undef $rcb;
		1359	}
		1360	};
		1361
		1362	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1363
		1364	bless \\$cb, "AnyEvent::Base::idle"
		1365	}
		1366
		1367	sub AnyEvent::Base::idle::DESTROY {
		1368	undef $${$_[0]};
1112	}	1369	}
1113		1370
1114	package AnyEvent::CondVar;	1371	package AnyEvent::CondVar;
1115		1372
1116	our @ISA = AnyEvent::CondVar::Base::;	1373	our @ISA = AnyEvent::CondVar::Base::;
…		…
1168	}	1425	}
1169		1426
1170	# undocumented/compatibility with pre-3.4	1427	# undocumented/compatibility with pre-3.4
1171	*broadcast = \&send;	1428	*broadcast = \&send;
1172	*wait = \&_wait;	1429	*wait = \&_wait;
		1430
		1431	=head1 ERROR AND EXCEPTION HANDLING
		1432
		1433	In general, AnyEvent does not do any error handling - it relies on the
		1434	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1435	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1436	checking of all AnyEvent methods, however, which is highly useful during
		1437	development.
		1438
		1439	As for exception handling (i.e. runtime errors and exceptions thrown while
		1440	executing a callback), this is not only highly event-loop specific, but
		1441	also not in any way wrapped by this module, as this is the job of the main
		1442	program.
		1443
		1444	The pure perl event loop simply re-throws the exception (usually
		1445	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1446	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1447	so on.
		1448
		1449	=head1 ENVIRONMENT VARIABLES
		1450
		1451	The following environment variables are used by this module or its
		1452	submodules.
		1453
		1454	Note that AnyEvent will remove I<all> environment variables starting with
		1455	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1456	enabled.
		1457
		1458	=over 4
		1459
		1460	=item C<PERL_ANYEVENT_VERBOSE>
		1461
		1462	By default, AnyEvent will be completely silent except in fatal
		1463	conditions. You can set this environment variable to make AnyEvent more
		1464	talkative.
		1465
		1466	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1467	conditions, such as not being able to load the event model specified by
		1468	C<PERL_ANYEVENT_MODEL>.
		1469
		1470	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1471	model it chooses.
		1472
		1473	=item C<PERL_ANYEVENT_STRICT>
		1474
		1475	AnyEvent does not do much argument checking by default, as thorough
		1476	argument checking is very costly. Setting this variable to a true value
		1477	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1478	check the arguments passed to most method calls. If it finds any problems,
		1479	it will croak.
		1480
		1481	In other words, enables "strict" mode.
		1482
		1483	Unlike C<use strict>, it is definitely recommended to keep it off in
		1484	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1485	developing programs can be very useful, however.
		1486
		1487	=item C<PERL_ANYEVENT_MODEL>
		1488
		1489	This can be used to specify the event model to be used by AnyEvent, before
		1490	auto detection and -probing kicks in. It must be a string consisting
		1491	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1492	and the resulting module name is loaded and if the load was successful,
		1493	used as event model. If it fails to load AnyEvent will proceed with
		1494	auto detection and -probing.
		1495
		1496	This functionality might change in future versions.
		1497
		1498	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1499	could start your program like this:
		1500
		1501	PERL_ANYEVENT_MODEL=Perl perl ...
		1502
		1503	=item C<PERL_ANYEVENT_PROTOCOLS>
		1504
		1505	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1506	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1507	of auto probing).
		1508
		1509	Must be set to a comma-separated list of protocols or address families,
		1510	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1511	used, and preference will be given to protocols mentioned earlier in the
		1512	list.
		1513
		1514	This variable can effectively be used for denial-of-service attacks
		1515	against local programs (e.g. when setuid), although the impact is likely
		1516	small, as the program has to handle conenction and other failures anyways.
		1517
		1518	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1519	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1520	- only support IPv4, never try to resolve or contact IPv6
		1521	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1522	IPv6, but prefer IPv6 over IPv4.
		1523
		1524	=item C<PERL_ANYEVENT_EDNS0>
		1525
		1526	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1527	for DNS. This extension is generally useful to reduce DNS traffic, but
		1528	some (broken) firewalls drop such DNS packets, which is why it is off by
		1529	default.
		1530
		1531	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1532	EDNS0 in its DNS requests.
		1533
		1534	=item C<PERL_ANYEVENT_MAX_FORKS>
		1535
		1536	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1537	will create in parallel.
		1538
		1539	=item C<PERL_ANYEVENT_MAX_OUTSTANDING_DNS>
		1540
		1541	The default value for the C<max_outstanding> parameter for the default DNS
		1542	resolver - this is the maximum number of parallel DNS requests that are
		1543	sent to the DNS server.
		1544
		1545	=item C<PERL_ANYEVENT_RESOLV_CONF>
		1546
		1547	The file to use instead of F</etc/resolv.conf> (or OS-specific
		1548	configuration) in the default resolver. When set to the empty string, no
		1549	default config will be used.
		1550
		1551	=item C<PERL_ANYEVENT_CA_FILE>, C<PERL_ANYEVENT_CA_PATH>.
		1552
		1553	When neither C<ca_file> nor C<ca_path> was specified during
		1554	L<AnyEvent::TLS> context creation, and either of these environment
		1555	variables exist, they will be used to specify CA certificate locations
		1556	instead of a system-dependent default.
		1557
		1558	=back
1173		1559
1174	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1560	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1175		1561
1176	This is an advanced topic that you do not normally need to use AnyEvent in	1562	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	1563	a module. This section is only of use to event loop authors who want to
…		…
1211		1597
1212	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1598	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1213	condition variables: code blocking while waiting for a condition will	1599	condition variables: code blocking while waiting for a condition will
1214	C<die>. This still works with most modules/usages, and blocking calls must	1600	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.	1601	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		1602
1303	=head1 EXAMPLE PROGRAM	1603	=head1 EXAMPLE PROGRAM
1304		1604
1305	The following program uses an I/O watcher to read data from STDIN, a timer	1605	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	1606	to display a message once per second, and a condition variable to quit the
…		…
1500	watcher.	1800	watcher.
1501		1801
1502	=head3 Results	1802	=head3 Results
1503		1803
1504	name watchers bytes create invoke destroy comment	1804	name watchers bytes create invoke destroy comment
1505	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1805	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	1806	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	1807	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	1808	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	1809	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	1810	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1811	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1812	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	1813	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	1814	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	1815	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	1816	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1515		1817
1516	=head3 Discussion	1818	=head3 Discussion
1517		1819
1518	The benchmark does I<not> measure scalability of the event loop very	1820	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)	1821	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	1846	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.	1847	them active), of course, but this was not subject of this benchmark.
1546		1848
1547	The C<Event> module has a relatively high setup and callback invocation	1849	The C<Event> module has a relatively high setup and callback invocation
1548	cost, but overall scores in on the third place.	1850	cost, but overall scores in on the third place.
		1851
		1852	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1853	when using its pure perl backend.
1549		1854
1550	C<Glib>'s memory usage is quite a bit higher, but it features a	1855	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	1856	faster callback invocation and overall ends up in the same class as
1552	C<Event>. However, Glib scales extremely badly, doubling the number of	1857	C<Event>. However, Glib scales extremely badly, doubling the number of
1553	watchers increases the processing time by more than a factor of four,	1858	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	1936	it to another server. This includes deleting the old timeout and creating
1632	a new one that moves the timeout into the future.	1937	a new one that moves the timeout into the future.
1633		1938
1634	=head3 Results	1939	=head3 Results
1635		1940
1636	name sockets create request	1941	name sockets create request
1637	EV 20000 69.01 11.16	1942	EV 20000 69.01 11.16
1638	Perl 20000 73.32 35.87	1943	Perl 20000 73.32 35.87
		1944	IOAsync 20000 157.00 98.14 epoll
		1945	IOAsync 20000 159.31 616.06 poll
1639	Event 20000 212.62 257.32	1946	Event 20000 212.62 257.32
1640	Glib 20000 651.16 1896.30	1947	Glib 20000 651.16 1896.30
1641	POE 20000 349.67 12317.24 uses POE::Loop::Event	1948	POE 20000 349.67 12317.24 uses POE::Loop::Event
1642		1949
1643	=head3 Discussion	1950	=head3 Discussion
1644		1951
1645	This benchmark I<does> measure scalability and overall performance of the	1952	This benchmark I<does> measure scalability and overall performance of the
1646	particular event loop.	1953	particular event loop.
…		…
1648	EV is again fastest. Since it is using epoll on my system, the setup time	1955	EV is again fastest. Since it is using epoll on my system, the setup time
1649	is relatively high, though.	1956	is relatively high, though.
1650		1957
1651	Perl surprisingly comes second. It is much faster than the C-based event	1958	Perl surprisingly comes second. It is much faster than the C-based event
1652	loops Event and Glib.	1959	loops Event and Glib.
		1960
		1961	IO::Async performs very well when using its epoll backend, and still quite
		1962	good compared to Glib when using its pure perl backend.
1653		1963
1654	Event suffers from high setup time as well (look at its code and you will	1964	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	1965	understand why). Callback invocation also has a high overhead compared to
1656	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1966	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1657	uses select or poll in basically all documented configurations.	1967	uses select or poll in basically all documented configurations.
…		…
1720	=item * C-based event loops perform very well with small number of	2030	=item * C-based event loops perform very well with small number of
1721	watchers, as the management overhead dominates.	2031	watchers, as the management overhead dominates.
1722		2032
1723	=back	2033	=back
1724		2034
		2035	=head2 THE IO::Lambda BENCHMARK
		2036
		2037	Recently I was told about the benchmark in the IO::Lambda manpage, which
		2038	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		2039	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		2040	shouldn't come as a surprise to anybody). As such, the benchmark is
		2041	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		2042	very optimal. But how would AnyEvent compare when used without the extra
		2043	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		2044
		2045	The benchmark itself creates an echo-server, and then, for 500 times,
		2046	connects to the echo server, sends a line, waits for the reply, and then
		2047	creates the next connection. This is a rather bad benchmark, as it doesn't
		2048	test the efficiency of the framework or much non-blocking I/O, but it is a
		2049	benchmark nevertheless.
		2050
		2051	name runtime
		2052	Lambda/select 0.330 sec
		2053	+ optimized 0.122 sec
		2054	Lambda/AnyEvent 0.327 sec
		2055	+ optimized 0.138 sec
		2056	Raw sockets/select 0.077 sec
		2057	POE/select, components 0.662 sec
		2058	POE/select, raw sockets 0.226 sec
		2059	POE/select, optimized 0.404 sec
		2060
		2061	AnyEvent/select/nb 0.085 sec
		2062	AnyEvent/EV/nb 0.068 sec
		2063	+state machine 0.134 sec
		2064
		2065	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		2066	benchmarks actually make blocking connects and use 100% blocking I/O,
		2067	defeating the purpose of an event-based solution. All of the newly
		2068	written AnyEvent benchmarks use 100% non-blocking connects (using
		2069	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		2070	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		2071	generally require a lot more bookkeeping and event handling than blocking
		2072	connects (which involve a single syscall only).
		2073
		2074	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		2075	offers similar expressive power as POE and IO::Lambda, using conventional
		2076	Perl syntax. This means that both the echo server and the client are 100%
		2077	non-blocking, further placing it at a disadvantage.
		2078
		2079	As you can see, the AnyEvent + EV combination even beats the
		2080	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		2081	backend easily beats IO::Lambda and POE.
		2082
		2083	And even the 100% non-blocking version written using the high-level (and
		2084	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2085	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2086	in a non-blocking way.
		2087
		2088	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2089	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2090	part of the IO::lambda distribution and were used without any changes.
		2091
		2092
		2093	=head1 SIGNALS
		2094
		2095	AnyEvent currently installs handlers for these signals:
		2096
		2097	=over 4
		2098
		2099	=item SIGCHLD
		2100
		2101	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2102	emulation for event loops that do not support them natively. Also, some
		2103	event loops install a similar handler.
		2104
		2105	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		2106	reset it to default, to avoid losing child exit statuses.
		2107
		2108	=item SIGPIPE
		2109
		2110	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2111	when AnyEvent gets loaded.
		2112
		2113	The rationale for this is that AnyEvent users usually do not really depend
		2114	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2115	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2116	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2117	some random socket.
		2118
		2119	The rationale for installing a no-op handler as opposed to ignoring it is
		2120	that this way, the handler will be restored to defaults on exec.
		2121
		2122	Feel free to install your own handler, or reset it to defaults.
		2123
		2124	=back
		2125
		2126	=cut
		2127
		2128	undef $SIG{CHLD}
		2129	if $SIG{CHLD} eq 'IGNORE';
		2130
		2131	$SIG{PIPE} = sub { }
		2132	unless defined $SIG{PIPE};
1725		2133
1726	=head1 FORK	2134	=head1 FORK
1727		2135
1728	Most event libraries are not fork-safe. The ones who are usually are	2136	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>	2137	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1750	use AnyEvent;	2158	use AnyEvent;
1751		2159
1752	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2160	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	2161	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	2162	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
1755	$ENV{PERL_ANYEGENT_STRICT}.	2163	$ENV{PERL_ANYEVENT_STRICT}.
		2164
		2165	Note that AnyEvent will remove I<all> environment variables starting with
		2166	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2167	enabled.
1756		2168
1757		2169
1758	=head1 BUGS	2170	=head1 BUGS
1759		2171
1760	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2172	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	2173	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	2174	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	2175	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1764	pronounced).	2176	pronounced).
1765		2177
1766		2178
1767	=head1 SEE ALSO	2179	=head1 SEE ALSO
1768		2180
…		…
1772	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.	2184	L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>, L<POE>.
1773		2185
1774	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,	2186	Implementations: L<AnyEvent::Impl::EV>, L<AnyEvent::Impl::Event>,
1775	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,	2187	L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>,
1776	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,	2188	L<AnyEvent::Impl::EventLib>, L<AnyEvent::Impl::Qt>,
1777	L<AnyEvent::Impl::POE>.	2189	L<AnyEvent::Impl::POE>, L<AnyEvent::Impl::IOAsync>.
1778		2190
1779	Non-blocking file handles, sockets, TCP clients and	2191	Non-blocking file handles, sockets, TCP clients and
1780	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>.	2192	servers: L<AnyEvent::Handle>, L<AnyEvent::Socket>, L<AnyEvent::TLS>.
1781		2193
1782	Asynchronous DNS: L<AnyEvent::DNS>.	2194	Asynchronous DNS: L<AnyEvent::DNS>.
1783		2195
1784	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>, L<Coro::Event>,	2196	Coroutine support: L<Coro>, L<Coro::AnyEvent>, L<Coro::EV>,
		2197	L<Coro::Event>,
1785		2198
1786	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>, L<AnyEvent::DNS>.	2199	Nontrivial usage examples: L<AnyEvent::GPSD>, L<AnyEvent::XMPP>,
		2200	L<AnyEvent::HTTP>.
1787		2201
1788		2202
1789	=head1 AUTHOR	2203	=head1 AUTHOR
1790		2204
1791	Marc Lehmann <schmorp@schmorp.de>	2205	Marc Lehmann <schmorp@schmorp.de>

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Revision 1.173 by root, Mon Jul 21 03:47:22 2008 UTC vs.
Revision 1.234 by root, Thu Jul 9 08:31:16 2009 UTC