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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.164 by root, Tue Jul 8 19:50:25 2008 UTC vs.
Revision 1.224 by root, Fri Jul 3 21:44:14 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 { ... });
		14
		15	# one-shot or repeating timers
		16	my $w = AnyEvent->timer (after => $seconds, cb => sub { ... });
		17	my $w = AnyEvent->timer (after => $seconds, interval => $seconds, cb => ...
		18
		19	print AnyEvent->now; # prints current event loop time
		20	print AnyEvent->time; # think Time::HiRes::time or simply CORE::time.
		21
		22	# POSIX signal
		23	my $w = AnyEvent->signal (signal => "TERM", cb => sub { ... });
		24
		25	# child process exit
		26	my $w = AnyEvent->child (pid => $pid, cb => sub {
		27	my ($pid, $status) = @_;
12	...	28	...
13	});	29	});
14		30
15	my $w = AnyEvent->timer (after => $seconds, cb => sub {	31	# called when event loop idle (if applicable)
16	...	32	my $w = AnyEvent->idle (cb => sub { ... });
17	});
18		33
19	my $w = AnyEvent->condvar; # stores whether a condition was flagged	34	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	$w->send; # wake up current and all future recv's	35	$w->send; # wake up current and all future recv's
21	$w->recv; # enters "main loop" till $condvar gets ->send	36	$w->recv; # enters "main loop" till $condvar gets ->send
		37	# use a condvar in callback mode:
		38	$w->cb (sub { $_[0]->recv });
22		39
23	=head1 INTRODUCTION/TUTORIAL	40	=head1 INTRODUCTION/TUTORIAL
24		41
25	This manpage is mainly a reference manual. If you are interested	42	This manpage is mainly a reference manual. If you are interested
26	in a tutorial or some gentle introduction, have a look at the	43	in a tutorial or some gentle introduction, have a look at the
33		50
34	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of	51	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
35	policy> and AnyEvent is I<small and efficient>.	52	policy> and AnyEvent is I<small and efficient>.
36		53
37	First and foremost, I<AnyEvent is not an event model> itself, it only	54	First and foremost, I<AnyEvent is not an event model> itself, it only
38	interfaces to whatever event model the main program happens to use in a	55	interfaces to whatever event model the main program happens to use, in a
39	pragmatic way. For event models and certain classes of immortals alike,	56	pragmatic way. For event models and certain classes of immortals alike,
40	the statement "there can only be one" is a bitter reality: In general,	57	the statement "there can only be one" is a bitter reality: In general,
41	only one event loop can be active at the same time in a process. AnyEvent	58	only one event loop can be active at the same time in a process. AnyEvent
42	helps hiding the differences between those event loops.	59	cannot change this, but it can hide the differences between those event
		60	loops.
43		61
44	The goal of AnyEvent is to offer module authors the ability to do event	62	The goal of AnyEvent is to offer module authors the ability to do event
45	programming (waiting for I/O or timer events) without subscribing to a	63	programming (waiting for I/O or timer events) without subscribing to a
46	religion, a way of living, and most importantly: without forcing your	64	religion, a way of living, and most importantly: without forcing your
47	module users into the same thing by forcing them to use the same event	65	module users into the same thing by forcing them to use the same event
48	model you use.	66	model you use.
49		67
50	For modules like POE or IO::Async (which is a total misnomer as it is	68	For modules like POE or IO::Async (which is a total misnomer as it is
51	actually doing all I/O I<synchronously>...), using them in your module is	69	actually doing all I/O I<synchronously>...), using them in your module is
52	like joining a cult: After you joined, you are dependent on them and you	70	like joining a cult: After you joined, you are dependent on them and you
53	cannot use anything else, as it is simply incompatible to everything that	71	cannot use anything else, as they are simply incompatible to everything
54	isn't itself. What's worse, all the potential users of your module are	72	that isn't them. What's worse, all the potential users of your
55	I<also> forced to use the same event loop you use.	73	module are I<also> forced to use the same event loop you use.
56		74
57	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works	75	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
58	fine. AnyEvent + Tk works fine etc. etc. but none of these work together	76	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
59	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if	77	with the rest: POE + IO::Async? No go. Tk + Event? No go. Again: if
60	your module uses one of those, every user of your module has to use it,	78	your module uses one of those, every user of your module has to use it,
61	too. But if your module uses AnyEvent, it works transparently with all	79	too. But if your module uses AnyEvent, it works transparently with all
62	event models it supports (including stuff like POE and IO::Async, as long	80	event models it supports (including stuff like IO::Async, as long as those
63	as those use one of the supported event loops. It is trivial to add new	81	use one of the supported event loops. It is trivial to add new event loops
64	event loops to AnyEvent, too, so it is future-proof).	82	to AnyEvent, too, so it is future-proof).
65		83
66	In addition to being free of having to use I<the one and only true event	84	In addition to being free of having to use I<the one and only true event
67	model>, AnyEvent also is free of bloat and policy: with POE or similar	85	model>, AnyEvent also is free of bloat and policy: with POE or similar
68	modules, you get an enormous amount of code and strict rules you have to	86	modules, you get an enormous amount of code and strict rules you have to
69	follow. AnyEvent, on the other hand, is lean and up to the point, by only	87	follow. AnyEvent, on the other hand, is lean and up to the point, by only
…		…
127	These watchers are normal Perl objects with normal Perl lifetime. After	145	These watchers are normal Perl objects with normal Perl lifetime. After
128	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
129	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
130	is in control).	148	is in control).
131		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
132	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
133	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
134	to it).	158	to it).
135		159
136	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.
…		…
152	=head2 I/O WATCHERS	176	=head2 I/O WATCHERS
153		177
154	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
155	with the following mandatory key-value pairs as arguments:	179	with the following mandatory key-value pairs as arguments:
156		180
157	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch	181	C<fh> is the Perl I<file handle> (I<not> file descriptor) to watch
		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
158	for events. C<poll> must be a string that is either C<r> or C<w>,	188	C<poll> must be a string that is either C<r> or C<w>, which creates a
159	which creates a watcher waiting for "r"eadable or "w"ritable events,	189	watcher waiting for "r"eadable or "w"ritable events, respectively.
		190
160	respectively. C<cb> is the callback to invoke each time the file handle	191	C<cb> is the callback to invoke each time the file handle becomes ready.
161	becomes ready.
162		192
163	Although the callback might get passed parameters, their value and	193	Although the callback might get passed parameters, their value and
164	presence is undefined and you cannot rely on them. Portable AnyEvent	194	presence is undefined and you cannot rely on them. Portable AnyEvent
165	callbacks cannot use arguments passed to I/O watcher callbacks.	195	callbacks cannot use arguments passed to I/O watcher callbacks.
166		196
…		…
193	Although the callback might get passed parameters, their value and	223	Although the callback might get passed parameters, their value and
194	presence is undefined and you cannot rely on them. Portable AnyEvent	224	presence is undefined and you cannot rely on them. Portable AnyEvent
195	callbacks cannot use arguments passed to time watcher callbacks.	225	callbacks cannot use arguments passed to time watcher callbacks.
196		226
197	The callback will normally be invoked once only. If you specify another	227	The callback will normally be invoked once only. If you specify another
198	parameter, C<interval>, as a positive number, then the callback will be	228	parameter, C<interval>, as a strictly positive number (> 0), then the
199	invoked regularly at that interval (in fractional seconds) after the first	229	callback will be invoked regularly at that interval (in fractional
200	invocation.	230	seconds) after the first invocation. If C<interval> is specified with a
		231	false value, then it is treated as if it were missing.
201		232
202	The callback will be rescheduled before invoking the callback, but no	233	The callback will be rescheduled before invoking the callback, but no
203	attempt is done to avoid timer drift in most backends, so the interval is	234	attempt is done to avoid timer drift in most backends, so the interval is
204	only approximate.	235	only approximate.
205		236
…		…
297	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
298	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
299	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into	330	difference between C<< AnyEvent->time >> and C<< AnyEvent->now >> into
300	account.	331	account.
301		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
302	=back	348	=back
303		349
304	=head2 SIGNAL WATCHERS	350	=head2 SIGNAL WATCHERS
305		351
306	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
307	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to	353	I<name> in uppercase and without any C<SIG> prefix, C<cb> is the Perl
308	be invoked whenever a signal occurs.	354	callback to be invoked whenever a signal occurs.
309		355
310	Although the callback might get passed parameters, their value and	356	Although the callback might get passed parameters, their value and
311	presence is undefined and you cannot rely on them. Portable AnyEvent	357	presence is undefined and you cannot rely on them. Portable AnyEvent
312	callbacks cannot use arguments passed to signal watcher callbacks.	358	callbacks cannot use arguments passed to signal watcher callbacks.
313		359
…		…
329	=head2 CHILD PROCESS WATCHERS	375	=head2 CHILD PROCESS WATCHERS
330		376
331	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.
332		378
333	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
334	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
335	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
336	signal handler for C<SIGCHLD>. The callback will be called with the pid	382	any trace events (stopped/continued).
337	and exit status (as returned by waitpid), so unlike other watcher types,	383
338	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).
339		392
340	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
341	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
342	have exited already (and no SIGCHLD will be sent anymore).	395	have exited already (and no SIGCHLD will be sent anymore).
343		396
344	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
345	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
346	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.
347		403
348	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
349	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
350	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>).
351		408
352	Example: fork a process and wait for it	409	Example: fork a process and wait for it
353		410
354	my $done = AnyEvent->condvar;	411	my $done = AnyEvent->condvar;
355		412
…		…
365	);	422	);
366		423
367	# do something else, then wait for process exit	424	# do something else, then wait for process exit
368	$done->recv;	425	$done->recv;
369		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
370	=head2 CONDITION VARIABLES	462	=head2 CONDITION VARIABLES
371		463
372	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
373	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
374	will actively watch for new events and call your callbacks.	466	will actively watch for new events and call your callbacks.
…		…
379	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
380	because they represent a condition that must become true.	472	because they represent a condition that must become true.
381		473
382	Condition variables can be created by calling the C<< AnyEvent->condvar	474	Condition variables can be created by calling the C<< AnyEvent->condvar
383	>> method, usually without arguments. The only argument pair allowed is	475	>> method, usually without arguments. The only argument pair allowed is
		476
384	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
385	becomes true.	478	becomes true, with the condition variable as the first argument (but not
		479	the results).
386		480
387	After creation, the condition variable is "false" until it becomes "true"	481	After creation, the condition variable is "false" until it becomes "true"
388	by calling the C<send> method (or calling the condition variable as if it	482	by calling the C<send> method (or calling the condition variable as if it
389	were a callback, read about the caveats in the description for the C<<	483	were a callback, read about the caveats in the description for the C<<
390	->send >> method).	484	->send >> method).
…		…
446		540
447	my $done = AnyEvent->condvar;	541	my $done = AnyEvent->condvar;
448	my $delay = AnyEvent->timer (after => 5, cb => $done);	542	my $delay = AnyEvent->timer (after => 5, cb => $done);
449	$done->recv;	543	$done->recv;
450		544
		545	Example: Imagine an API that returns a condvar and doesn't support
		546	callbacks. This is how you make a synchronous call, for example from
		547	the main program:
		548
		549	use AnyEvent::CouchDB;
		550
		551	...
		552
		553	my @info = $couchdb->info->recv;
		554
		555	And this is how you would just ste a callback to be called whenever the
		556	results are available:
		557
		558	$couchdb->info->cb (sub {
		559	my @info = $_[0]->recv;
		560	});
		561
451	=head3 METHODS FOR PRODUCERS	562	=head3 METHODS FOR PRODUCERS
452		563
453	These methods should only be used by the producing side, i.e. the	564	These methods should only be used by the producing side, i.e. the
454	code/module that eventually sends the signal. Note that it is also	565	code/module that eventually sends the signal. Note that it is also
455	the producer side which creates the condvar in most cases, but it isn't	566	the producer side which creates the condvar in most cases, but it isn't
…		…
488		599
489	=item $cv->begin ([group callback])	600	=item $cv->begin ([group callback])
490		601
491	=item $cv->end	602	=item $cv->end
492		603
493	These two methods are EXPERIMENTAL and MIGHT CHANGE.
494
495	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
496	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
497	to use a condition variable for the whole process.	606	to use a condition variable for the whole process.
498		607
499	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
500	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
501	>>, 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
502	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
503	callback was set, C<send> will be called without any arguments.	612	callback was set, C<send> will be called without any arguments.
504		613
505	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:
506		645
507	my $cv = AnyEvent->condvar;	646	my $cv = AnyEvent->condvar;
508		647
509	my %result;	648	my %result;
510	$cv->begin (sub { $cv->send (\%result) });	649	$cv->begin (sub { $cv->send (\%result) });
…		…
530	loop, which serves two important purposes: first, it sets the callback	669	loop, which serves two important purposes: first, it sets the callback
531	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
532	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
533	doesn't execute once).	672	doesn't execute once).
534		673
535	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
536	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
537	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
538	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>.
539		679
540	=back	680	=back
541		681
542	=head3 METHODS FOR CONSUMERS	682	=head3 METHODS FOR CONSUMERS
543		683
…		…
588	=item $bool = $cv->ready	728	=item $bool = $cv->ready
589		729
590	Returns true when the condition is "true", i.e. whether C<send> or	730	Returns true when the condition is "true", i.e. whether C<send> or
591	C<croak> have been called.	731	C<croak> have been called.
592		732
593	=item $cb = $cv->cb ([new callback])	733	=item $cb = $cv->cb ($cb->($cv))
594		734
595	This is a mutator function that returns the callback set and optionally	735	This is a mutator function that returns the callback set and optionally
596	replaces it before doing so.	736	replaces it before doing so.
597		737
598	The callback will be called when the condition becomes "true", i.e. when	738	The callback will be called when the condition becomes "true", i.e. when
…		…
623	AnyEvent::Impl::Tk based on Tk, very bad choice.	763	AnyEvent::Impl::Tk based on Tk, very bad choice.
624	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).	764	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
625	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.	765	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
626	AnyEvent::Impl::POE based on POE, not generic enough for full support.	766	AnyEvent::Impl::POE based on POE, not generic enough for full support.
627		767
		768	# warning, support for IO::Async is only partial, as it is too broken
		769	# and limited toe ven support the AnyEvent API. See AnyEvent::Impl::Async.
		770	AnyEvent::Impl::IOAsync based on IO::Async, cannot be autoprobed (see its docs).
		771
628	There is no support for WxWidgets, as WxWidgets has no support for	772	There is no support for WxWidgets, as WxWidgets has no support for
629	watching file handles. However, you can use WxWidgets through the	773	watching file handles. However, you can use WxWidgets through the
630	POE Adaptor, as POE has a Wx backend that simply polls 20 times per	774	POE Adaptor, as POE has a Wx backend that simply polls 20 times per
631	second, which was considered to be too horrible to even consider for	775	second, which was considered to be too horrible to even consider for
632	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using	776	AnyEvent. Likewise, other POE backends can be used by AnyEvent by using
…		…
788	=item L<AnyEvent::IGS>	932	=item L<AnyEvent::IGS>
789		933
790	A non-blocking interface to the Internet Go Server protocol (used by	934	A non-blocking interface to the Internet Go Server protocol (used by
791	L<App::IGS>).	935	L<App::IGS>).
792		936
793	=item L<Net::IRC3>	937	=item L<AnyEvent::IRC>
794		938
795	AnyEvent based IRC client module family.	939	AnyEvent based IRC client module family (replacing the older Net::IRC3).
796		940
797	=item L<Net::XMPP2>	941	=item L<Net::XMPP2>
798		942
799	AnyEvent based XMPP (Jabber protocol) module family.	943	AnyEvent based XMPP (Jabber protocol) module family.
800		944
…		…
820	=cut	964	=cut
821		965
822	package AnyEvent;	966	package AnyEvent;
823		967
824	no warnings;	968	no warnings;
825	use strict;	969	use strict qw(vars subs);
826		970
827	use Carp;	971	use Carp;
828		972
829	our $VERSION = 4.2;	973	our $VERSION = 4.452;
830	our $MODEL;	974	our $MODEL;
831		975
832	our $AUTOLOAD;	976	our $AUTOLOAD;
833	our @ISA;	977	our @ISA;
834		978
835	our @REGISTRY;	979	our @REGISTRY;
836		980
837	our $WIN32;	981	our $WIN32;
838		982
839	BEGIN {	983	BEGIN {
840	my $win32 = ! ! ($^O =~ /mswin32/i);	984	eval "sub WIN32(){ " . (($^O =~ /mswin32/i)*1) ." }";
841	eval "sub WIN32(){ $win32 }";	985	eval "sub TAINT(){ " . (${^TAINT}*1) . " }";
		986
		987	delete @ENV{grep /^PERL_ANYEVENT_/, keys %ENV}
		988	if ${^TAINT};
842	}	989	}
843		990
844	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;	991	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
845		992
846	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred	993	our %PROTOCOL; # (ipv4\|ipv6) => (1\|2), higher numbers are preferred
…		…
864	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy	1011	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
865	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program	1012	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
866	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza	1013	[POE::Kernel:: => AnyEvent::Impl::POE::], # lasciate ogni speranza
867	[Wx:: => AnyEvent::Impl::POE::],	1014	[Wx:: => AnyEvent::Impl::POE::],
868	[Prima:: => AnyEvent::Impl::POE::],	1015	[Prima:: => AnyEvent::Impl::POE::],
		1016	# IO::Async is just too broken - we would need workaorunds for its
		1017	# byzantine signal and broken child handling, among others.
		1018	# IO::Async is rather hard to detect, as it doesn't have any
		1019	# obvious default class.
		1020	# [IO::Async:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1021	# [IO::Async::Loop:: => AnyEvent::Impl::IOAsync::], # requires special main program
		1022	# [IO::Async::Notifier:: => AnyEvent::Impl::IOAsync::], # requires special main program
869	);	1023	);
870		1024
871	our %method = map +($_ => 1), qw(io timer time now signal child condvar one_event DESTROY);	1025	our %method = map +($_ => 1),
		1026	qw(io timer time now now_update signal child idle condvar one_event DESTROY);
872		1027
873	our @post_detect;	1028	our @post_detect;
874		1029
875	sub post_detect(&) {	1030	sub post_detect(&) {
876	my ($cb) = @_;	1031	my ($cb) = @_;
…		…
881	1	1036	1
882	} else {	1037	} else {
883	push @post_detect, $cb;	1038	push @post_detect, $cb;
884		1039
885	defined wantarray	1040	defined wantarray
886	? bless \$cb, "AnyEvent::Util::PostDetect"	1041	? bless \$cb, "AnyEvent::Util::postdetect"
887	: ()	1042	: ()
888	}	1043	}
889	}	1044	}
890		1045
891	sub AnyEvent::Util::PostDetect::DESTROY {	1046	sub AnyEvent::Util::postdetect::DESTROY {
892	@post_detect = grep $_ != ${$_[0]}, @post_detect;	1047	@post_detect = grep $_ != ${$_[0]}, @post_detect;
893	}	1048	}
894		1049
895	sub detect() {	1050	sub detect() {
896	unless ($MODEL) {	1051	unless ($MODEL) {
…		…
933	last;	1088	last;
934	}	1089	}
935	}	1090	}
936		1091
937	$MODEL	1092	$MODEL
938	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.";	1093	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV, Event or Glib.\n";
939	}	1094	}
940	}	1095	}
941		1096
		1097	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
		1098
942	unshift @ISA, $MODEL;	1099	unshift @ISA, $MODEL;
943	push @{"$MODEL\::ISA"}, "AnyEvent::Base";	1100
		1101	require AnyEvent::Strict if $ENV{PERL_ANYEVENT_STRICT};
944		1102
945	(shift @post_detect)->() while @post_detect;	1103	(shift @post_detect)->() while @post_detect;
946	}	1104	}
947		1105
948	$MODEL	1106	$MODEL
…		…
958		1116
959	my $class = shift;	1117	my $class = shift;
960	$class->$func (@_);	1118	$class->$func (@_);
961	}	1119	}
962		1120
		1121	# utility function to dup a filehandle. this is used by many backends
		1122	# to support binding more than one watcher per filehandle (they usually
		1123	# allow only one watcher per fd, so we dup it to get a different one).
		1124	sub _dupfh($$;$$) {
		1125	my ($poll, $fh, $r, $w) = @_;
		1126
		1127	# cygwin requires the fh mode to be matching, unix doesn't
		1128	my ($rw, $mode) = $poll eq "r" ? ($r, "<")
		1129	: $poll eq "w" ? ($w, ">")
		1130	: Carp::croak "AnyEvent->io requires poll set to either 'r' or 'w'";
		1131
		1132	open my $fh2, "$mode&" . fileno $fh
		1133	or die "cannot dup() filehandle: $!,";
		1134
		1135	# we assume CLOEXEC is already set by perl in all important cases
		1136
		1137	($fh2, $rw)
		1138	}
		1139
963	package AnyEvent::Base;	1140	package AnyEvent::Base;
964		1141
965	# default implementation for now and time	1142	# default implementations for many methods
966		1143
967	use Time::HiRes ();	1144	BEGIN {
		1145	if (eval "use Time::HiRes (); Time::HiRes::time (); 1") {
		1146	*_time = \&Time::HiRes::time;
		1147	# if (eval "use POSIX (); (POSIX::times())...
		1148	} else {
		1149	*_time = sub { time }; # epic fail
		1150	}
		1151	}
968		1152
969	sub time { Time::HiRes::time }	1153	sub time { _time }
970	sub now { Time::HiRes::time }	1154	sub now { _time }
		1155	sub now_update { }
971		1156
972	# default implementation for ->condvar	1157	# default implementation for ->condvar
973		1158
974	sub condvar {	1159	sub condvar {
975	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, AnyEvent::CondVar::	1160	bless { @_ == 3 ? (_ae_cb => $_[2]) : () }, "AnyEvent::CondVar"
976	}	1161	}
977		1162
978	# default implementation for ->signal	1163	# default implementation for ->signal
979		1164
980	our %SIG_CB;	1165	our ($SIGPIPE_R, $SIGPIPE_W, %SIG_CB, %SIG_EV, $SIG_IO);
		1166
		1167	sub _signal_exec {
		1168	sysread $SIGPIPE_R, my $dummy, 4;
		1169
		1170	while (%SIG_EV) {
		1171	for (keys %SIG_EV) {
		1172	delete $SIG_EV{$_};
		1173	$_->() for values %{ $SIG_CB{$_} \|\| {} };
		1174	}
		1175	}
		1176	}
981		1177
982	sub signal {	1178	sub signal {
983	my (undef, %arg) = @_;	1179	my (undef, %arg) = @_;
984		1180
		1181	unless ($SIGPIPE_R) {
		1182	require Fcntl;
		1183
		1184	if (AnyEvent::WIN32) {
		1185	require AnyEvent::Util;
		1186
		1187	($SIGPIPE_R, $SIGPIPE_W) = AnyEvent::Util::portable_pipe ();
		1188	AnyEvent::Util::fh_nonblocking ($SIGPIPE_R) if $SIGPIPE_R;
		1189	AnyEvent::Util::fh_nonblocking ($SIGPIPE_W) if $SIGPIPE_W; # just in case
		1190	} else {
		1191	pipe $SIGPIPE_R, $SIGPIPE_W;
		1192	fcntl $SIGPIPE_R, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_R;
		1193	fcntl $SIGPIPE_W, &Fcntl::F_SETFL, &Fcntl::O_NONBLOCK if $SIGPIPE_W; # just in case
		1194
		1195	# not strictly required, as $^F is normally 2, but let's make sure...
		1196	fcntl $SIGPIPE_R, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1197	fcntl $SIGPIPE_W, &Fcntl::F_SETFD, &Fcntl::FD_CLOEXEC;
		1198	}
		1199
		1200	$SIGPIPE_R
		1201	or Carp::croak "AnyEvent: unable to create a signal reporting pipe: $!\n";
		1202
		1203	$SIG_IO = AnyEvent->io (fh => $SIGPIPE_R, poll => "r", cb => \&_signal_exec);
		1204	}
		1205
985	my $signal = uc $arg{signal}	1206	my $signal = uc $arg{signal}
986	or Carp::croak "required option 'signal' is missing";	1207	or Carp::croak "required option 'signal' is missing";
987		1208
988	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};	1209	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
989	$SIG{$signal} \|\|= sub {	1210	$SIG{$signal} \|\|= sub {
990	$_->() for values %{ $SIG_CB{$signal} \|\| {} };	1211	local $!;
		1212	syswrite $SIGPIPE_W, "\x00", 1 unless %SIG_EV;
		1213	undef $SIG_EV{$signal};
991	};	1214	};
992		1215
993	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"	1216	bless [$signal, $arg{cb}], "AnyEvent::Base::signal"
994	}	1217	}
995		1218
996	sub AnyEvent::Base::Signal::DESTROY {	1219	sub AnyEvent::Base::signal::DESTROY {
997	my ($signal, $cb) = @{$_[0]};	1220	my ($signal, $cb) = @{$_[0]};
998		1221
999	delete $SIG_CB{$signal}{$cb};	1222	delete $SIG_CB{$signal}{$cb};
1000		1223
		1224	# delete doesn't work with older perls - they then
		1225	# print weird messages, or just unconditionally exit
		1226	# instead of getting the default action.
1001	delete $SIG{$signal} unless keys %{ $SIG_CB{$signal} };	1227	undef $SIG{$signal} unless keys %{ $SIG_CB{$signal} };
1002	}	1228	}
1003		1229
1004	# default implementation for ->child	1230	# default implementation for ->child
1005		1231
1006	our %PID_CB;	1232	our %PID_CB;
1007	our $CHLD_W;	1233	our $CHLD_W;
1008	our $CHLD_DELAY_W;	1234	our $CHLD_DELAY_W;
1009	our $PID_IDLE;
1010	our $WNOHANG;	1235	our $WNOHANG;
1011		1236
1012	sub _child_wait {	1237	sub _sigchld {
1013	while (0 < (my $pid = waitpid -1, $WNOHANG)) {	1238	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
1014	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),	1239	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
1015	(values %{ $PID_CB{0} \|\| {} });	1240	(values %{ $PID_CB{0} \|\| {} });
1016	}	1241	}
1017
1018	undef $PID_IDLE;
1019	}
1020
1021	sub _sigchld {
1022	# make sure we deliver these changes "synchronous" with the event loop.
1023	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
1024	undef $CHLD_DELAY_W;
1025	&_child_wait;
1026	});
1027	}	1242	}
1028		1243
1029	sub child {	1244	sub child {
1030	my (undef, %arg) = @_;	1245	my (undef, %arg) = @_;
1031		1246
1032	defined (my $pid = $arg{pid} + 0)	1247	defined (my $pid = $arg{pid} + 0)
1033	or Carp::croak "required option 'pid' is missing";	1248	or Carp::croak "required option 'pid' is missing";
1034		1249
1035	$PID_CB{$pid}{$arg{cb}} = $arg{cb};	1250	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
1036		1251
1037	unless ($WNOHANG) {
1038	$WNOHANG = eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;	1252	$WNOHANG \|\|= eval { local $SIG{__DIE__}; require POSIX; &POSIX::WNOHANG } \|\| 1;
1039	}
1040		1253
1041	unless ($CHLD_W) {	1254	unless ($CHLD_W) {
1042	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);	1255	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
1043	# child could be a zombie already, so make at least one round	1256	# child could be a zombie already, so make at least one round
1044	&_sigchld;	1257	&_sigchld;
1045	}	1258	}
1046		1259
1047	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"	1260	bless [$pid, $arg{cb}], "AnyEvent::Base::child"
1048	}	1261	}
1049		1262
1050	sub AnyEvent::Base::Child::DESTROY {	1263	sub AnyEvent::Base::child::DESTROY {
1051	my ($pid, $cb) = @{$_[0]};	1264	my ($pid, $cb) = @{$_[0]};
1052		1265
1053	delete $PID_CB{$pid}{$cb};	1266	delete $PID_CB{$pid}{$cb};
1054	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };	1267	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
1055		1268
1056	undef $CHLD_W unless keys %PID_CB;	1269	undef $CHLD_W unless keys %PID_CB;
		1270	}
		1271
		1272	# idle emulation is done by simply using a timer, regardless
		1273	# of whether the process is idle or not, and not letting
		1274	# the callback use more than 50% of the time.
		1275	sub idle {
		1276	my (undef, %arg) = @_;
		1277
		1278	my ($cb, $w, $rcb) = $arg{cb};
		1279
		1280	$rcb = sub {
		1281	if ($cb) {
		1282	$w = _time;
		1283	&$cb;
		1284	$w = _time - $w;
		1285
		1286	# never use more then 50% of the time for the idle watcher,
		1287	# within some limits
		1288	$w = 0.0001 if $w < 0.0001;
		1289	$w = 5 if $w > 5;
		1290
		1291	$w = AnyEvent->timer (after => $w, cb => $rcb);
		1292	} else {
		1293	# clean up...
		1294	undef $w;
		1295	undef $rcb;
		1296	}
		1297	};
		1298
		1299	$w = AnyEvent->timer (after => 0.05, cb => $rcb);
		1300
		1301	bless \\$cb, "AnyEvent::Base::idle"
		1302	}
		1303
		1304	sub AnyEvent::Base::idle::DESTROY {
		1305	undef $${$_[0]};
1057	}	1306	}
1058		1307
1059	package AnyEvent::CondVar;	1308	package AnyEvent::CondVar;
1060		1309
1061	our @ISA = AnyEvent::CondVar::Base::;	1310	our @ISA = AnyEvent::CondVar::Base::;
…		…
1113	}	1362	}
1114		1363
1115	# undocumented/compatibility with pre-3.4	1364	# undocumented/compatibility with pre-3.4
1116	*broadcast = \&send;	1365	*broadcast = \&send;
1117	*wait = \&_wait;	1366	*wait = \&_wait;
		1367
		1368	=head1 ERROR AND EXCEPTION HANDLING
		1369
		1370	In general, AnyEvent does not do any error handling - it relies on the
		1371	caller to do that if required. The L<AnyEvent::Strict> module (see also
		1372	the C<PERL_ANYEVENT_STRICT> environment variable, below) provides strict
		1373	checking of all AnyEvent methods, however, which is highly useful during
		1374	development.
		1375
		1376	As for exception handling (i.e. runtime errors and exceptions thrown while
		1377	executing a callback), this is not only highly event-loop specific, but
		1378	also not in any way wrapped by this module, as this is the job of the main
		1379	program.
		1380
		1381	The pure perl event loop simply re-throws the exception (usually
		1382	within C<< condvar->recv >>), the L<Event> and L<EV> modules call C<<
		1383	$Event/EV::DIED->() >>, L<Glib> uses C<< install_exception_handler >> and
		1384	so on.
		1385
		1386	=head1 ENVIRONMENT VARIABLES
		1387
		1388	The following environment variables are used by this module or its
		1389	submodules.
		1390
		1391	Note that AnyEvent will remove I<all> environment variables starting with
		1392	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		1393	enabled.
		1394
		1395	=over 4
		1396
		1397	=item C<PERL_ANYEVENT_VERBOSE>
		1398
		1399	By default, AnyEvent will be completely silent except in fatal
		1400	conditions. You can set this environment variable to make AnyEvent more
		1401	talkative.
		1402
		1403	When set to C<1> or higher, causes AnyEvent to warn about unexpected
		1404	conditions, such as not being able to load the event model specified by
		1405	C<PERL_ANYEVENT_MODEL>.
		1406
		1407	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		1408	model it chooses.
		1409
		1410	=item C<PERL_ANYEVENT_STRICT>
		1411
		1412	AnyEvent does not do much argument checking by default, as thorough
		1413	argument checking is very costly. Setting this variable to a true value
		1414	will cause AnyEvent to load C<AnyEvent::Strict> and then to thoroughly
		1415	check the arguments passed to most method calls. If it finds any problems,
		1416	it will croak.
		1417
		1418	In other words, enables "strict" mode.
		1419
		1420	Unlike C<use strict>, it is definitely recommended to keep it off in
		1421	production. Keeping C<PERL_ANYEVENT_STRICT=1> in your environment while
		1422	developing programs can be very useful, however.
		1423
		1424	=item C<PERL_ANYEVENT_MODEL>
		1425
		1426	This can be used to specify the event model to be used by AnyEvent, before
		1427	auto detection and -probing kicks in. It must be a string consisting
		1428	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		1429	and the resulting module name is loaded and if the load was successful,
		1430	used as event model. If it fails to load AnyEvent will proceed with
		1431	auto detection and -probing.
		1432
		1433	This functionality might change in future versions.
		1434
		1435	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		1436	could start your program like this:
		1437
		1438	PERL_ANYEVENT_MODEL=Perl perl ...
		1439
		1440	=item C<PERL_ANYEVENT_PROTOCOLS>
		1441
		1442	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
		1443	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
		1444	of auto probing).
		1445
		1446	Must be set to a comma-separated list of protocols or address families,
		1447	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
		1448	used, and preference will be given to protocols mentioned earlier in the
		1449	list.
		1450
		1451	This variable can effectively be used for denial-of-service attacks
		1452	against local programs (e.g. when setuid), although the impact is likely
		1453	small, as the program has to handle conenction and other failures anyways.
		1454
		1455	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
		1456	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
		1457	- only support IPv4, never try to resolve or contact IPv6
		1458	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
		1459	IPv6, but prefer IPv6 over IPv4.
		1460
		1461	=item C<PERL_ANYEVENT_EDNS0>
		1462
		1463	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
		1464	for DNS. This extension is generally useful to reduce DNS traffic, but
		1465	some (broken) firewalls drop such DNS packets, which is why it is off by
		1466	default.
		1467
		1468	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
		1469	EDNS0 in its DNS requests.
		1470
		1471	=item C<PERL_ANYEVENT_MAX_FORKS>
		1472
		1473	The maximum number of child processes that C<AnyEvent::Util::fork_call>
		1474	will create in parallel.
		1475
		1476	=back
1118		1477
1119	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE	1478	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
1120		1479
1121	This is an advanced topic that you do not normally need to use AnyEvent in	1480	This is an advanced topic that you do not normally need to use AnyEvent in
1122	a module. This section is only of use to event loop authors who want to	1481	a module. This section is only of use to event loop authors who want to
…		…
1156		1515
1157	I<rxvt-unicode> also cheats a bit by not providing blocking access to	1516	I<rxvt-unicode> also cheats a bit by not providing blocking access to
1158	condition variables: code blocking while waiting for a condition will	1517	condition variables: code blocking while waiting for a condition will
1159	C<die>. This still works with most modules/usages, and blocking calls must	1518	C<die>. This still works with most modules/usages, and blocking calls must
1160	not be done in an interactive application, so it makes sense.	1519	not be done in an interactive application, so it makes sense.
1161
1162	=head1 ENVIRONMENT VARIABLES
1163
1164	The following environment variables are used by this module:
1165
1166	=over 4
1167
1168	=item C<PERL_ANYEVENT_VERBOSE>
1169
1170	By default, AnyEvent will be completely silent except in fatal
1171	conditions. You can set this environment variable to make AnyEvent more
1172	talkative.
1173
1174	When set to C<1> or higher, causes AnyEvent to warn about unexpected
1175	conditions, such as not being able to load the event model specified by
1176	C<PERL_ANYEVENT_MODEL>.
1177
1178	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
1179	model it chooses.
1180
1181	=item C<PERL_ANYEVENT_MODEL>
1182
1183	This can be used to specify the event model to be used by AnyEvent, before
1184	auto detection and -probing kicks in. It must be a string consisting
1185	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
1186	and the resulting module name is loaded and if the load was successful,
1187	used as event model. If it fails to load AnyEvent will proceed with
1188	auto detection and -probing.
1189
1190	This functionality might change in future versions.
1191
1192	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
1193	could start your program like this:
1194
1195	PERL_ANYEVENT_MODEL=Perl perl ...
1196
1197	=item C<PERL_ANYEVENT_PROTOCOLS>
1198
1199	Used by both L<AnyEvent::DNS> and L<AnyEvent::Socket> to determine preferences
1200	for IPv4 or IPv6. The default is unspecified (and might change, or be the result
1201	of auto probing).
1202
1203	Must be set to a comma-separated list of protocols or address families,
1204	current supported: C<ipv4> and C<ipv6>. Only protocols mentioned will be
1205	used, and preference will be given to protocols mentioned earlier in the
1206	list.
1207
1208	This variable can effectively be used for denial-of-service attacks
1209	against local programs (e.g. when setuid), although the impact is likely
1210	small, as the program has to handle connection errors already-
1211
1212	Examples: C<PERL_ANYEVENT_PROTOCOLS=ipv4,ipv6> - prefer IPv4 over IPv6,
1213	but support both and try to use both. C<PERL_ANYEVENT_PROTOCOLS=ipv4>
1214	- only support IPv4, never try to resolve or contact IPv6
1215	addresses. C<PERL_ANYEVENT_PROTOCOLS=ipv6,ipv4> support either IPv4 or
1216	IPv6, but prefer IPv6 over IPv4.
1217
1218	=item C<PERL_ANYEVENT_EDNS0>
1219
1220	Used by L<AnyEvent::DNS> to decide whether to use the EDNS0 extension
1221	for DNS. This extension is generally useful to reduce DNS traffic, but
1222	some (broken) firewalls drop such DNS packets, which is why it is off by
1223	default.
1224
1225	Setting this variable to C<1> will cause L<AnyEvent::DNS> to announce
1226	EDNS0 in its DNS requests.
1227
1228	=item C<PERL_ANYEVENT_MAX_FORKS>
1229
1230	The maximum number of child processes that C<AnyEvent::Util::fork_call>
1231	will create in parallel.
1232
1233	=back
1234		1520
1235	=head1 EXAMPLE PROGRAM	1521	=head1 EXAMPLE PROGRAM
1236		1522
1237	The following program uses an I/O watcher to read data from STDIN, a timer	1523	The following program uses an I/O watcher to read data from STDIN, a timer
1238	to display a message once per second, and a condition variable to quit the	1524	to display a message once per second, and a condition variable to quit the
…		…
1432	watcher.	1718	watcher.
1433		1719
1434	=head3 Results	1720	=head3 Results
1435		1721
1436	name watchers bytes create invoke destroy comment	1722	name watchers bytes create invoke destroy comment
1437	EV/EV 400000 244 0.56 0.46 0.31 EV native interface	1723	EV/EV 400000 224 0.47 0.35 0.27 EV native interface
1438	EV/Any 100000 244 2.50 0.46 0.29 EV + AnyEvent watchers	1724	EV/Any 100000 224 2.88 0.34 0.27 EV + AnyEvent watchers
1439	CoroEV/Any 100000 244 2.49 0.44 0.29 coroutines + Coro::Signal	1725	CoroEV/Any 100000 224 2.85 0.35 0.28 coroutines + Coro::Signal
1440	Perl/Any 100000 513 4.92 0.87 1.12 pure perl implementation	1726	Perl/Any 100000 452 4.13 0.73 0.95 pure perl implementation
1441	Event/Event 16000 516 31.88 31.30 0.85 Event native interface	1727	Event/Event 16000 517 32.20 31.80 0.81 Event native interface
1442	Event/Any 16000 590 35.75 31.42 1.08 Event + AnyEvent watchers	1728	Event/Any 16000 590 35.85 31.55 1.06 Event + AnyEvent watchers
		1729	IOAsync/Any 16000 989 38.10 32.77 11.13 via IO::Async::Loop::IO_Poll
		1730	IOAsync/Any 16000 990 37.59 29.50 10.61 via IO::Async::Loop::Epoll
1443	Glib/Any 16000 1357 98.22 12.41 54.00 quadratic behaviour	1731	Glib/Any 16000 1357 102.33 12.31 51.00 quadratic behaviour
1444	Tk/Any 2000 1860 26.97 67.98 14.00 SEGV with >> 2000 watchers	1732	Tk/Any 2000 1860 27.20 66.31 14.00 SEGV with >> 2000 watchers
1445	POE/Event 2000 6644 108.64 736.02 14.73 via POE::Loop::Event	1733	POE/Event 2000 6328 109.99 751.67 14.02 via POE::Loop::Event
1446	POE/Select 2000 6343 94.13 809.12 565.96 via POE::Loop::Select	1734	POE/Select 2000 6027 94.54 809.13 579.80 via POE::Loop::Select
1447		1735
1448	=head3 Discussion	1736	=head3 Discussion
1449		1737
1450	The benchmark does I<not> measure scalability of the event loop very	1738	The benchmark does I<not> measure scalability of the event loop very
1451	well. For example, a select-based event loop (such as the pure perl one)	1739	well. For example, a select-based event loop (such as the pure perl one)
…		…
1476	performance becomes really bad with lots of file descriptors (and few of	1764	performance becomes really bad with lots of file descriptors (and few of
1477	them active), of course, but this was not subject of this benchmark.	1765	them active), of course, but this was not subject of this benchmark.
1478		1766
1479	The C<Event> module has a relatively high setup and callback invocation	1767	The C<Event> module has a relatively high setup and callback invocation
1480	cost, but overall scores in on the third place.	1768	cost, but overall scores in on the third place.
		1769
		1770	C<IO::Async> performs admirably well, about on par with C<Event>, even
		1771	when using its pure perl backend.
1481		1772
1482	C<Glib>'s memory usage is quite a bit higher, but it features a	1773	C<Glib>'s memory usage is quite a bit higher, but it features a
1483	faster callback invocation and overall ends up in the same class as	1774	faster callback invocation and overall ends up in the same class as
1484	C<Event>. However, Glib scales extremely badly, doubling the number of	1775	C<Event>. However, Glib scales extremely badly, doubling the number of
1485	watchers increases the processing time by more than a factor of four,	1776	watchers increases the processing time by more than a factor of four,
…		…
1563	it to another server. This includes deleting the old timeout and creating	1854	it to another server. This includes deleting the old timeout and creating
1564	a new one that moves the timeout into the future.	1855	a new one that moves the timeout into the future.
1565		1856
1566	=head3 Results	1857	=head3 Results
1567		1858
1568	name sockets create request	1859	name sockets create request
1569	EV 20000 69.01 11.16	1860	EV 20000 69.01 11.16
1570	Perl 20000 73.32 35.87	1861	Perl 20000 73.32 35.87
		1862	IOAsync 20000 157.00 98.14 epoll
		1863	IOAsync 20000 159.31 616.06 poll
1571	Event 20000 212.62 257.32	1864	Event 20000 212.62 257.32
1572	Glib 20000 651.16 1896.30	1865	Glib 20000 651.16 1896.30
1573	POE 20000 349.67 12317.24 uses POE::Loop::Event	1866	POE 20000 349.67 12317.24 uses POE::Loop::Event
1574		1867
1575	=head3 Discussion	1868	=head3 Discussion
1576		1869
1577	This benchmark I<does> measure scalability and overall performance of the	1870	This benchmark I<does> measure scalability and overall performance of the
1578	particular event loop.	1871	particular event loop.
…		…
1580	EV is again fastest. Since it is using epoll on my system, the setup time	1873	EV is again fastest. Since it is using epoll on my system, the setup time
1581	is relatively high, though.	1874	is relatively high, though.
1582		1875
1583	Perl surprisingly comes second. It is much faster than the C-based event	1876	Perl surprisingly comes second. It is much faster than the C-based event
1584	loops Event and Glib.	1877	loops Event and Glib.
		1878
		1879	IO::Async performs very well when using its epoll backend, and still quite
		1880	good compared to Glib when using its pure perl backend.
1585		1881
1586	Event suffers from high setup time as well (look at its code and you will	1882	Event suffers from high setup time as well (look at its code and you will
1587	understand why). Callback invocation also has a high overhead compared to	1883	understand why). Callback invocation also has a high overhead compared to
1588	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event	1884	the C<< $_->() for .. >>-style loop that the Perl event loop uses. Event
1589	uses select or poll in basically all documented configurations.	1885	uses select or poll in basically all documented configurations.
…		…
1652	=item * C-based event loops perform very well with small number of	1948	=item * C-based event loops perform very well with small number of
1653	watchers, as the management overhead dominates.	1949	watchers, as the management overhead dominates.
1654		1950
1655	=back	1951	=back
1656		1952
		1953	=head2 THE IO::Lambda BENCHMARK
		1954
		1955	Recently I was told about the benchmark in the IO::Lambda manpage, which
		1956	could be misinterpreted to make AnyEvent look bad. In fact, the benchmark
		1957	simply compares IO::Lambda with POE, and IO::Lambda looks better (which
		1958	shouldn't come as a surprise to anybody). As such, the benchmark is
		1959	fine, and mostly shows that the AnyEvent backend from IO::Lambda isn't
		1960	very optimal. But how would AnyEvent compare when used without the extra
		1961	baggage? To explore this, I wrote the equivalent benchmark for AnyEvent.
		1962
		1963	The benchmark itself creates an echo-server, and then, for 500 times,
		1964	connects to the echo server, sends a line, waits for the reply, and then
		1965	creates the next connection. This is a rather bad benchmark, as it doesn't
		1966	test the efficiency of the framework or much non-blocking I/O, but it is a
		1967	benchmark nevertheless.
		1968
		1969	name runtime
		1970	Lambda/select 0.330 sec
		1971	+ optimized 0.122 sec
		1972	Lambda/AnyEvent 0.327 sec
		1973	+ optimized 0.138 sec
		1974	Raw sockets/select 0.077 sec
		1975	POE/select, components 0.662 sec
		1976	POE/select, raw sockets 0.226 sec
		1977	POE/select, optimized 0.404 sec
		1978
		1979	AnyEvent/select/nb 0.085 sec
		1980	AnyEvent/EV/nb 0.068 sec
		1981	+state machine 0.134 sec
		1982
		1983	The benchmark is also a bit unfair (my fault): the IO::Lambda/POE
		1984	benchmarks actually make blocking connects and use 100% blocking I/O,
		1985	defeating the purpose of an event-based solution. All of the newly
		1986	written AnyEvent benchmarks use 100% non-blocking connects (using
		1987	AnyEvent::Socket::tcp_connect and the asynchronous pure perl DNS
		1988	resolver), so AnyEvent is at a disadvantage here, as non-blocking connects
		1989	generally require a lot more bookkeeping and event handling than blocking
		1990	connects (which involve a single syscall only).
		1991
		1992	The last AnyEvent benchmark additionally uses L<AnyEvent::Handle>, which
		1993	offers similar expressive power as POE and IO::Lambda, using conventional
		1994	Perl syntax. This means that both the echo server and the client are 100%
		1995	non-blocking, further placing it at a disadvantage.
		1996
		1997	As you can see, the AnyEvent + EV combination even beats the
		1998	hand-optimised "raw sockets benchmark", while AnyEvent + its pure perl
		1999	backend easily beats IO::Lambda and POE.
		2000
		2001	And even the 100% non-blocking version written using the high-level (and
		2002	slow :) L<AnyEvent::Handle> abstraction beats both POE and IO::Lambda by a
		2003	large margin, even though it does all of DNS, tcp-connect and socket I/O
		2004	in a non-blocking way.
		2005
		2006	The two AnyEvent benchmarks programs can be found as F<eg/ae0.pl> and
		2007	F<eg/ae2.pl> in the AnyEvent distribution, the remaining benchmarks are
		2008	part of the IO::lambda distribution and were used without any changes.
		2009
		2010
		2011	=head1 SIGNALS
		2012
		2013	AnyEvent currently installs handlers for these signals:
		2014
		2015	=over 4
		2016
		2017	=item SIGCHLD
		2018
		2019	A handler for C<SIGCHLD> is installed by AnyEvent's child watcher
		2020	emulation for event loops that do not support them natively. Also, some
		2021	event loops install a similar handler.
		2022
		2023	If, when AnyEvent is loaded, SIGCHLD is set to IGNORE, then AnyEvent will
		2024	reset it to default, to avoid losing child exit statuses.
		2025
		2026	=item SIGPIPE
		2027
		2028	A no-op handler is installed for C<SIGPIPE> when C<$SIG{PIPE}> is C<undef>
		2029	when AnyEvent gets loaded.
		2030
		2031	The rationale for this is that AnyEvent users usually do not really depend
		2032	on SIGPIPE delivery (which is purely an optimisation for shell use, or
		2033	badly-written programs), but C<SIGPIPE> can cause spurious and rare
		2034	program exits as a lot of people do not expect C<SIGPIPE> when writing to
		2035	some random socket.
		2036
		2037	The rationale for installing a no-op handler as opposed to ignoring it is
		2038	that this way, the handler will be restored to defaults on exec.
		2039
		2040	Feel free to install your own handler, or reset it to defaults.
		2041
		2042	=back
		2043
		2044	=cut
		2045
		2046	undef $SIG{CHLD}
		2047	if $SIG{CHLD} eq 'IGNORE';
		2048
		2049	$SIG{PIPE} = sub { }
		2050	unless defined $SIG{PIPE};
1657		2051
1658	=head1 FORK	2052	=head1 FORK
1659		2053
1660	Most event libraries are not fork-safe. The ones who are usually are	2054	Most event libraries are not fork-safe. The ones who are usually are
1661	because they rely on inefficient but fork-safe C<select> or C<poll>	2055	because they rely on inefficient but fork-safe C<select> or C<poll>
…		…
1681		2075
1682	use AnyEvent;	2076	use AnyEvent;
1683		2077
1684	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can	2078	Similar considerations apply to $ENV{PERL_ANYEVENT_VERBOSE}, as that can
1685	be used to probe what backend is used and gain other information (which is	2079	be used to probe what backend is used and gain other information (which is
1686	probably even less useful to an attacker than PERL_ANYEVENT_MODEL).	2080	probably even less useful to an attacker than PERL_ANYEVENT_MODEL), and
		2081	$ENV{PERL_ANYEVENT_STRICT}.
		2082
		2083	Note that AnyEvent will remove I<all> environment variables starting with
		2084	C<PERL_ANYEVENT_> from C<%ENV> when it is loaded while taint mode is
		2085	enabled.
1687		2086
1688		2087
1689	=head1 BUGS	2088	=head1 BUGS
1690		2089
1691	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard	2090	Perl 5.8 has numerous memleaks that sometimes hit this module and are hard
1692	to work around. If you suffer from memleaks, first upgrade to Perl 5.10	2091	to work around. If you suffer from memleaks, first upgrade to Perl 5.10
1693	and check wether the leaks still show up. (Perl 5.10.0 has other annoying	2092	and check wether the leaks still show up. (Perl 5.10.0 has other annoying
1694	mamleaks, such as leaking on C<map> and C<grep> but it is usually not as	2093	memleaks, such as leaking on C<map> and C<grep> but it is usually not as
1695	pronounced).	2094	pronounced).
1696		2095
1697		2096
1698	=head1 SEE ALSO	2097	=head1 SEE ALSO
1699		2098

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.164 by root, Tue Jul 8 19:50:25 2008 UTC vs. Revision 1.224 by root, Fri Jul 3 21:44:14 2009 UTC

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Revision 1.224 by root, Fri Jul 3 21:44:14 2009 UTC