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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.4 by root, Thu Dec 1 22:04:50 2005 UTC vs.
Revision 1.55 by root, Wed Apr 23 11:25:42 2008 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	Event, Coro, Glib, Tk - various supported event loops	5	EV, Event, Coro::EV, Coro::Event, Glib, Tk, Perl, Event::Lib - various supported event loops
6		6
7	=head1 SYNOPSIS	7	=head1 SYNOPSIS
8		8
9	use AnyEvent;	9	use AnyEvent;
10		10
11	my $w = AnyEvent->timer (fh => ..., poll => "[rw]+", cb => sub {	11	my $w = AnyEvent->io (fh => $fh, poll => "r\|w", cb => sub {
12	my ($poll_got) = @_;
13	...	12	...
14	});	13	});
		14
15	my $w = AnyEvent->io (after => $seconds, cb => sub {	15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
16	...	16	...
17	});	17	});
18		18
19	# watchers get canceled whenever $w is destroyed	19	my $w = AnyEvent->condvar; # stores whether a condition was flagged
20	# only one watcher per $fh and $poll type is allowed
21	# (i.e. on a socket you cna have one r + one w or one rw
22	# watcher, not any more.
23	# timers can only be used once
24
25	my $w = AnyEvent->condvar; # kind of main loop replacement
26	# can only be used once
27	$w->wait; # enters main loop till $condvar gets ->send	20	$w->wait; # enters "main loop" till $condvar gets ->broadcast
28	$w->broadcast; # wake up waiting and future wait's	21	$w->broadcast; # wake up current and all future wait's
		22
		23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
		24
		25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
		26	nowadays. So what is different about AnyEvent?
		27
		28	Executive Summary: AnyEvent is I<compatible>, AnyEvent is I<free of
		29	policy> and AnyEvent is I<small and efficient>.
		30
		31	First and foremost, I<AnyEvent is not an event model> itself, it only
		32	interfaces to whatever event model the main program happens to use in a
		33	pragmatic way. For event models and certain classes of immortals alike,
		34	the statement "there can only be one" is a bitter reality: In general,
		35	only one event loop can be active at the same time in a process. AnyEvent
		36	helps hiding the differences between those event loops.
		37
		38	The goal of AnyEvent is to offer module authors the ability to do event
		39	programming (waiting for I/O or timer events) without subscribing to a
		40	religion, a way of living, and most importantly: without forcing your
		41	module users into the same thing by forcing them to use the same event
		42	model you use.
		43
		44	For modules like POE or IO::Async (which is a total misnomer as it is
		45	actually doing all I/O I<synchronously>...), using them in your module is
		46	like joining a cult: After you joined, you are dependent on them and you
		47	cannot use anything else, as it is simply incompatible to everything that
		48	isn't itself. What's worse, all the potential users of your module are
		49	I<also> forced to use the same event loop you use.
		50
		51	AnyEvent is different: AnyEvent + POE works fine. AnyEvent + Glib works
		52	fine. AnyEvent + Tk works fine etc. etc. but none of these work together
		53	with the rest: POE + IO::Async? no go. Tk + Event? no go. Again: if
		54	your module uses one of those, every user of your module has to use it,
		55	too. But if your module uses AnyEvent, it works transparently with all
		56	event models it supports (including stuff like POE and IO::Async, as long
		57	as those use one of the supported event loops. It is trivial to add new
		58	event loops to AnyEvent, too, so it is future-proof).
		59
		60	In addition to being free of having to use I<the one and only true event
		61	model>, AnyEvent also is free of bloat and policy: with POE or similar
		62	modules, you get an enourmous amount of code and strict rules you have to
		63	follow. AnyEvent, on the other hand, is lean and up to the point, by only
		64	offering the functionality that is necessary, in as thin as a wrapper as
		65	technically possible.
		66
		67	Of course, if you want lots of policy (this can arguably be somewhat
		68	useful) and you want to force your users to use the one and only event
		69	model, you should I<not> use this module.
		70
29		71
30	=head1 DESCRIPTION	72	=head1 DESCRIPTION
31		73
32	L<AnyEvent> provides an identical interface to multiple event loops. This	74	L<AnyEvent> provides an identical interface to multiple event loops. This
33	allows module authors to utilizy an event loop without forcing module	75	allows module authors to utilise an event loop without forcing module
34	users to use the same event loop (as only a single event loop can coexist	76	users to use the same event loop (as only a single event loop can coexist
35	peacefully at any one time).	77	peacefully at any one time).
36		78
37	The interface itself is vaguely similar but not identical to the Event	79	The interface itself is vaguely similar, but not identical to the L<Event>
38	module.	80	module.
39		81
40	On the first call of any method, the module tries to detect the currently	82	During the first call of any watcher-creation method, the module tries
41	loaded event loop by probing wether any of the following modules is	83	to detect the currently loaded event loop by probing whether one of the
42	loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is	84	following modules is already loaded: L<Coro::EV>, L<Coro::Event>, L<EV>,
43	used. If none is found, the module tries to load these modules in the	85	L<Event>, L<Glib>, L<Tk>. The first one found is used. If none are found,
44	order given. The first one that could be successfully loaded will be	86	the module tries to load these modules in the stated order. The first one
45	used. If still none could be found, it will issue an error.	87	that can be successfully loaded will be used. If, after this, still none
		88	could be found, AnyEvent will fall back to a pure-perl event loop, which
		89	is not very efficient, but should work everywhere.
		90
		91	Because AnyEvent first checks for modules that are already loaded, loading
		92	an event model explicitly before first using AnyEvent will likely make
		93	that model the default. For example:
		94
		95	use Tk;
		96	use AnyEvent;
		97
		98	# .. AnyEvent will likely default to Tk
		99
		100	The I<likely> means that, if any module loads another event model and
		101	starts using it, all bets are off. Maybe you should tell their authors to
		102	use AnyEvent so their modules work together with others seamlessly...
		103
		104	The pure-perl implementation of AnyEvent is called
		105	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
		106	explicitly.
		107
		108	=head1 WATCHERS
		109
		110	AnyEvent has the central concept of a I<watcher>, which is an object that
		111	stores relevant data for each kind of event you are waiting for, such as
		112	the callback to call, the filehandle to watch, etc.
		113
		114	These watchers are normal Perl objects with normal Perl lifetime. After
		115	creating a watcher it will immediately "watch" for events and invoke the
		116	callback when the event occurs (of course, only when the event model
		117	is in control).
		118
		119	To disable the watcher you have to destroy it (e.g. by setting the
		120	variable you store it in to C<undef> or otherwise deleting all references
		121	to it).
		122
		123	All watchers are created by calling a method on the C<AnyEvent> class.
		124
		125	Many watchers either are used with "recursion" (repeating timers for
		126	example), or need to refer to their watcher object in other ways.
		127
		128	An any way to achieve that is this pattern:
		129
		130	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
		131	# you can use $w here, for example to undef it
		132	undef $w;
		133	});
		134
		135	Note that C<my $w; $w => combination. This is necessary because in Perl,
		136	my variables are only visible after the statement in which they are
		137	declared.
		138
		139	=head2 IO WATCHERS
		140
		141	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
		142	with the following mandatory key-value pairs as arguments:
		143
		144	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for
		145	events. C<poll> must be a string that is either C<r> or C<w>, which
		146	creates a watcher waiting for "r"eadable or "w"ritable events,
		147	respectively. C<cb> is the callback to invoke each time the file handle
		148	becomes ready.
		149
		150	File handles will be kept alive, so as long as the watcher exists, the
		151	file handle exists, too.
		152
		153	It is not allowed to close a file handle as long as any watcher is active
		154	on the underlying file descriptor.
		155
		156	Some event loops issue spurious readyness notifications, so you should
		157	always use non-blocking calls when reading/writing from/to your file
		158	handles.
		159
		160	Example:
		161
		162	# wait for readability of STDIN, then read a line and disable the watcher
		163	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		164	chomp (my $input = <STDIN>);
		165	warn "read: $input\n";
		166	undef $w;
		167	});
		168
		169	=head2 TIME WATCHERS
		170
		171	You can create a time watcher by calling the C<< AnyEvent->timer >>
		172	method with the following mandatory arguments:
		173
		174	C<after> specifies after how many seconds (fractional values are
		175	supported) should the timer activate. C<cb> the callback to invoke in that
		176	case.
		177
		178	The timer callback will be invoked at most once: if you want a repeating
		179	timer you have to create a new watcher (this is a limitation by both Tk
		180	and Glib).
		181
		182	Example:
		183
		184	# fire an event after 7.7 seconds
		185	my $w = AnyEvent->timer (after => 7.7, cb => sub {
		186	warn "timeout\n";
		187	});
		188
		189	# to cancel the timer:
		190	undef $w;
		191
		192	Example 2:
		193
		194	# fire an event after 0.5 seconds, then roughly every second
		195	my $w;
		196
		197	my $cb = sub {
		198	# cancel the old timer while creating a new one
		199	$w = AnyEvent->timer (after => 1, cb => $cb);
		200	};
		201
		202	# start the "loop" by creating the first watcher
		203	$w = AnyEvent->timer (after => 0.5, cb => $cb);
		204
		205	=head3 TIMING ISSUES
		206
		207	There are two ways to handle timers: based on real time (relative, "fire
		208	in 10 seconds") and based on wallclock time (absolute, "fire at 12
		209	o'clock").
		210
		211	While most event loops expect timers to specified in a relative way, they use
		212	absolute time internally. This makes a difference when your clock "jumps",
		213	for example, when ntp decides to set your clock backwards from the wrong 2014-01-01 to
		214	2008-01-01, a watcher that you created to fire "after" a second might actually take
		215	six years to finally fire.
		216
		217	AnyEvent cannot compensate for this. The only event loop that is conscious
		218	about these issues is L<EV>, which offers both relative (ev_timer) and
		219	absolute (ev_periodic) timers.
		220
		221	AnyEvent always prefers relative timers, if available, matching the
		222	AnyEvent API.
		223
		224	=head2 SIGNAL WATCHERS
		225
		226	You can watch for signals using a signal watcher, C<signal> is the signal
		227	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
		228	be invoked whenever a signal occurs.
		229
		230	Multiple signals occurances can be clumped together into one callback
		231	invocation, and callback invocation will be synchronous. synchronous means
		232	that it might take a while until the signal gets handled by the process,
		233	but it is guarenteed not to interrupt any other callbacks.
		234
		235	The main advantage of using these watchers is that you can share a signal
		236	between multiple watchers.
		237
		238	This watcher might use C<%SIG>, so programs overwriting those signals
		239	directly will likely not work correctly.
		240
		241	Example: exit on SIGINT
		242
		243	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
		244
		245	=head2 CHILD PROCESS WATCHERS
		246
		247	You can also watch on a child process exit and catch its exit status.
		248
		249	The child process is specified by the C<pid> argument (if set to C<0>, it
		250	watches for any child process exit). The watcher will trigger as often
		251	as status change for the child are received. This works by installing a
		252	signal handler for C<SIGCHLD>. The callback will be called with the pid
		253	and exit status (as returned by waitpid).
		254
		255	Example: wait for pid 1333
		256
		257	my $w = AnyEvent->child (
		258	pid => 1333,
		259	cb => sub {
		260	my ($pid, $status) = @_;
		261	warn "pid $pid exited with status $status";
		262	},
		263	);
		264
		265	=head2 CONDITION VARIABLES
		266
		267	Condition variables can be created by calling the C<< AnyEvent->condvar >>
		268	method without any arguments.
		269
		270	A condition variable waits for a condition - precisely that the C<<
		271	->broadcast >> method has been called.
		272
		273	They are very useful to signal that a condition has been fulfilled, for
		274	example, if you write a module that does asynchronous http requests,
		275	then a condition variable would be the ideal candidate to signal the
		276	availability of results.
		277
		278	You can also use condition variables to block your main program until
		279	an event occurs - for example, you could C<< ->wait >> in your main
		280	program until the user clicks the Quit button in your app, which would C<<
		281	->broadcast >> the "quit" event.
		282
		283	Note that condition variables recurse into the event loop - if you have
		284	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you
		285	lose. Therefore, condition variables are good to export to your caller, but
		286	you should avoid making a blocking wait yourself, at least in callbacks,
		287	as this asks for trouble.
		288
		289	This object has two methods:
46		290
47	=over 4	291	=over 4
48		292
		293	=item $cv->wait
		294
		295	Wait (blocking if necessary) until the C<< ->broadcast >> method has been
		296	called on c<$cv>, while servicing other watchers normally.
		297
		298	You can only wait once on a condition - additional calls will return
		299	immediately.
		300
		301	Not all event models support a blocking wait - some die in that case
		302	(programs might want to do that to stay interactive), so I<if you are
		303	using this from a module, never require a blocking wait>, but let the
		304	caller decide whether the call will block or not (for example, by coupling
		305	condition variables with some kind of request results and supporting
		306	callbacks so the caller knows that getting the result will not block,
		307	while still suppporting blocking waits if the caller so desires).
		308
		309	Another reason I<never> to C<< ->wait >> in a module is that you cannot
		310	sensibly have two C<< ->wait >>'s in parallel, as that would require
		311	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
		312	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
		313	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
		314	from different coroutines, however).
		315
		316	=item $cv->broadcast
		317
		318	Flag the condition as ready - a running C<< ->wait >> and all further
		319	calls to C<wait> will (eventually) return after this method has been
		320	called. If nobody is waiting the broadcast will be remembered..
		321
		322	=back
		323
		324	Example:
		325
		326	# wait till the result is ready
		327	my $result_ready = AnyEvent->condvar;
		328
		329	# do something such as adding a timer
		330	# or socket watcher the calls $result_ready->broadcast
		331	# when the "result" is ready.
		332	# in this case, we simply use a timer:
		333	my $w = AnyEvent->timer (
		334	after => 1,
		335	cb => sub { $result_ready->broadcast },
		336	);
		337
		338	# this "blocks" (while handling events) till the watcher
		339	# calls broadcast
		340	$result_ready->wait;
		341
		342	=head1 GLOBAL VARIABLES AND FUNCTIONS
		343
		344	=over 4
		345
		346	=item $AnyEvent::MODEL
		347
		348	Contains C<undef> until the first watcher is being created. Then it
		349	contains the event model that is being used, which is the name of the
		350	Perl class implementing the model. This class is usually one of the
		351	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
		352	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
		353
		354	The known classes so far are:
		355
		356	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
		357	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
		358	AnyEvent::Impl::EV based on EV (an interface to libev, also best choice).
		359	AnyEvent::Impl::Event based on Event, also second best choice :)
		360	AnyEvent::Impl::Glib based on Glib, third-best choice.
		361	AnyEvent::Impl::Tk based on Tk, very bad choice.
		362	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
		363	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		364
		365	=item AnyEvent::detect
		366
		367	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
		368	if necessary. You should only call this function right before you would
		369	have created an AnyEvent watcher anyway, that is, as late as possible at
		370	runtime.
		371
		372	=back
		373
		374	=head1 WHAT TO DO IN A MODULE
		375
		376	As a module author, you should C<use AnyEvent> and call AnyEvent methods
		377	freely, but you should not load a specific event module or rely on it.
		378
		379	Be careful when you create watchers in the module body - AnyEvent will
		380	decide which event module to use as soon as the first method is called, so
		381	by calling AnyEvent in your module body you force the user of your module
		382	to load the event module first.
		383
		384	Never call C<< ->wait >> on a condition variable unless you I<know> that
		385	the C<< ->broadcast >> method has been called on it already. This is
		386	because it will stall the whole program, and the whole point of using
		387	events is to stay interactive.
		388
		389	It is fine, however, to call C<< ->wait >> when the user of your module
		390	requests it (i.e. if you create a http request object ad have a method
		391	called C<results> that returns the results, it should call C<< ->wait >>
		392	freely, as the user of your module knows what she is doing. always).
		393
		394	=head1 WHAT TO DO IN THE MAIN PROGRAM
		395
		396	There will always be a single main program - the only place that should
		397	dictate which event model to use.
		398
		399	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
		400	do anything special (it does not need to be event-based) and let AnyEvent
		401	decide which implementation to chose if some module relies on it.
		402
		403	If the main program relies on a specific event model. For example, in
		404	Gtk2 programs you have to rely on the Glib module. You should load the
		405	event module before loading AnyEvent or any module that uses it: generally
		406	speaking, you should load it as early as possible. The reason is that
		407	modules might create watchers when they are loaded, and AnyEvent will
		408	decide on the event model to use as soon as it creates watchers, and it
		409	might chose the wrong one unless you load the correct one yourself.
		410
		411	You can chose to use a rather inefficient pure-perl implementation by
		412	loading the C<AnyEvent::Impl::Perl> module, which gives you similar
		413	behaviour everywhere, but letting AnyEvent chose is generally better.
		414
49	=cut	415	=cut
50		416
51	package AnyEvent;	417	package AnyEvent;
52		418
53	no warnings;	419	no warnings;
54	use strict 'vars';	420	use strict;
		421
55	use Carp;	422	use Carp;
56		423
57	our $VERSION = 0.2;	424	our $VERSION = '3.12';
58	our $MODEL;	425	our $MODEL;
59		426
60	our $AUTOLOAD;	427	our $AUTOLOAD;
61	our @ISA;	428	our @ISA;
62		429
		430	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		431
		432	our @REGISTRY;
		433
63	my @models = (	434	my @models = (
64	[Coro => Coro::Event::],	435	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
65	[Event => Event::],	436	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
66	[Glib => Glib::],	437	[EV:: => AnyEvent::Impl::EV::],
67	[Tk => Tk::],	438	[Event:: => AnyEvent::Impl::Event::],
		439	[Glib:: => AnyEvent::Impl::Glib::],
		440	[Tk:: => AnyEvent::Impl::Tk::],
		441	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
		442	[Event::Lib:: => AnyEvent::Impl::EventLib::],
68	);	443	);
69		444
70	our %method = map +($_ => 1), qw(io timer condvar broadcast wait cancel DESTROY);	445	our %method = map +($_ => 1), qw(io timer condvar broadcast wait signal one_event DESTROY);
71		446
72	sub AUTOLOAD {	447	sub detect() {
73	$AUTOLOAD =~ s/.*://;
74
75	$method{$AUTOLOAD}
76	or croak "$AUTOLOAD: not a valid method for AnyEvent objects";
77
78	unless ($MODEL) {	448	unless ($MODEL) {
79	# check for already loaded models	449	no strict 'refs';
80	for (@models) {	450
81	my ($model, $package) = @$_;	451	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
82	if (scalar keys %{ *{"$package\::"} }) {	452	my $model = "AnyEvent::Impl::$1";
83	eval "require AnyEvent::Impl::$model";	453	if (eval "require $model") {
84	last if $MODEL;	454	$MODEL = $model;
		455	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;
85	}	456	}
86	}	457	}
87		458
		459	# check for already loaded models
88	unless ($MODEL) {	460	unless ($MODEL) {
89	# try to load a model
90
91	for (@models) {	461	for (@REGISTRY, @models) {
92	my ($model, $package) = @$_;	462	my ($package, $model) = @$_;
93	eval "require AnyEvent::Impl::$model";	463	if (${"$package\::VERSION"} > 0) {
94	last if $MODEL;	464	if (eval "require $model") {
		465	$MODEL = $model;
		466	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
		467	last;
		468	}
		469	}
95	}	470	}
96		471
		472	unless ($MODEL) {
		473	# try to load a model
		474
		475	for (@REGISTRY, @models) {
		476	my ($package, $model) = @$_;
		477	if (eval "require $package"
		478	and ${"$package\::VERSION"} > 0
		479	and eval "require $model") {
		480	$MODEL = $model;
		481	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
		482	last;
		483	}
		484	}
		485
97	$MODEL	486	$MODEL
98	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk.";	487	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: EV (or Coro+EV), Event (or Coro+Event) or Glib.";
		488	}
99	}	489	}
		490
		491	unshift @ISA, $MODEL;
		492	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
100	}	493	}
101		494
102	@ISA = $MODEL;	495	$MODEL
		496	}
		497
		498	sub AUTOLOAD {
		499	(my $func = $AUTOLOAD) =~ s/.*://;
		500
		501	$method{$func}
		502	or croak "$func: not a valid method for AnyEvent objects";
		503
		504	detect unless $MODEL;
103		505
104	my $class = shift;	506	my $class = shift;
105	$class->$AUTOLOAD (@_);	507	$class->$func (@_);
106	}	508	}
		509
		510	package AnyEvent::Base;
		511
		512	# default implementation for ->condvar, ->wait, ->broadcast
		513
		514	sub condvar {
		515	bless \my $flag, "AnyEvent::Base::CondVar"
		516	}
		517
		518	sub AnyEvent::Base::CondVar::broadcast {
		519	${$_[0]}++;
		520	}
		521
		522	sub AnyEvent::Base::CondVar::wait {
		523	AnyEvent->one_event while !${$_[0]};
		524	}
		525
		526	# default implementation for ->signal
		527
		528	our %SIG_CB;
		529
		530	sub signal {
		531	my (undef, %arg) = @_;
		532
		533	my $signal = uc $arg{signal}
		534	or Carp::croak "required option 'signal' is missing";
		535
		536	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		537	$SIG{$signal} \|\|= sub {
		538	$_->() for values %{ $SIG_CB{$signal} \|\| {} };
		539	};
		540
		541	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
		542	}
		543
		544	sub AnyEvent::Base::Signal::DESTROY {
		545	my ($signal, $cb) = @{$_[0]};
		546
		547	delete $SIG_CB{$signal}{$cb};
		548
		549	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
		550	}
		551
		552	# default implementation for ->child
		553
		554	our %PID_CB;
		555	our $CHLD_W;
		556	our $CHLD_DELAY_W;
		557	our $PID_IDLE;
		558	our $WNOHANG;
		559
		560	sub _child_wait {
		561	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		562	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
		563	(values %{ $PID_CB{0} \|\| {} });
		564	}
		565
		566	undef $PID_IDLE;
		567	}
		568
		569	sub _sigchld {
		570	# make sure we deliver these changes "synchronous" with the event loop.
		571	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
		572	undef $CHLD_DELAY_W;
		573	&_child_wait;
		574	});
		575	}
		576
		577	sub child {
		578	my (undef, %arg) = @_;
		579
		580	defined (my $pid = $arg{pid} + 0)
		581	or Carp::croak "required option 'pid' is missing";
		582
		583	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
		584
		585	unless ($WNOHANG) {
		586	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;
		587	}
		588
		589	unless ($CHLD_W) {
		590	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
		591	# child could be a zombie already, so make at least one round
		592	&_sigchld;
		593	}
		594
		595	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"
		596	}
		597
		598	sub AnyEvent::Base::Child::DESTROY {
		599	my ($pid, $cb) = @{$_[0]};
		600
		601	delete $PID_CB{$pid}{$cb};
		602	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
		603
		604	undef $CHLD_W unless keys %PID_CB;
		605	}
		606
		607	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
		608
		609	This is an advanced topic that you do not normally need to use AnyEvent in
		610	a module. This section is only of use to event loop authors who want to
		611	provide AnyEvent compatibility.
		612
		613	If you need to support another event library which isn't directly
		614	supported by AnyEvent, you can supply your own interface to it by
		615	pushing, before the first watcher gets created, the package name of
		616	the event module and the package name of the interface to use onto
		617	C<@AnyEvent::REGISTRY>. You can do that before and even without loading
		618	AnyEvent, so it is reasonably cheap.
		619
		620	Example:
		621
		622	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
		623
		624	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
		625	package/class when it finds the C<urxvt> package/module is already loaded.
		626
		627	When AnyEvent is loaded and asked to find a suitable event model, it
		628	will first check for the presence of urxvt by trying to C<use> the
		629	C<urxvt::anyevent> module.
		630
		631	The class should provide implementations for all watcher types. See
		632	L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
		633	and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to
		634	see the sources.
		635
		636	If you don't provide C<signal> and C<child> watchers than AnyEvent will
		637	provide suitable (hopefully) replacements.
		638
		639	The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
		640	terminal emulator uses the above line as-is. An interface isn't included
		641	in AnyEvent because it doesn't make sense outside the embedded interpreter
		642	inside I<rxvt-unicode>, and it is updated and maintained as part of the
		643	I<rxvt-unicode> distribution.
		644
		645	I<rxvt-unicode> also cheats a bit by not providing blocking access to
		646	condition variables: code blocking while waiting for a condition will
		647	C<die>. This still works with most modules/usages, and blocking calls must
		648	not be done in an interactive application, so it makes sense.
		649
		650	=head1 ENVIRONMENT VARIABLES
		651
		652	The following environment variables are used by this module:
		653
		654	=over 4
		655
		656	=item C<PERL_ANYEVENT_VERBOSE>
		657
		658	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		659	model it chooses.
		660
		661	=item C<PERL_ANYEVENT_MODEL>
		662
		663	This can be used to specify the event model to be used by AnyEvent, before
		664	autodetection and -probing kicks in. It must be a string consisting
		665	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		666	and the resulting module name is loaded and if the load was successful,
		667	used as event model. If it fails to load AnyEvent will proceed with
		668	autodetection and -probing.
		669
		670	This functionality might change in future versions.
		671
		672	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		673	could start your program like this:
		674
		675	PERL_ANYEVENT_MODEL=Perl perl ...
107		676
108	=back	677	=back
109		678
110	=head1 EXAMPLE	679	=head1 EXAMPLE PROGRAM
111		680
112	The following program uses an io watcher to read data from stdin, a timer	681	The following program uses an IO watcher to read data from STDIN, a timer
113	to display a message once per second, and a condvar to exit the program	682	to display a message once per second, and a condition variable to quit the
114	when the user enters quit:	683	program when the user enters quit:
115		684
116	use AnyEvent;	685	use AnyEvent;
117		686
118	my $cv = AnyEvent->condvar;	687	my $cv = AnyEvent->condvar;
119		688
120	my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	689	my $io_watcher = AnyEvent->io (
		690	fh => \*STDIN,
		691	poll => 'r',
		692	cb => sub {
121	warn "io event <$_[0]>\n"; # will always output <r>	693	warn "io event <$_[0]>\n"; # will always output <r>
122	chomp (my $input = <STDIN>); # read a line	694	chomp (my $input = <STDIN>); # read a line
123	warn "read: $input\n"; # output what has been read	695	warn "read: $input\n"; # output what has been read
124	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	696	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
		697	},
125	});	698	);
126		699
127	my $time_watcher; # can only be used once	700	my $time_watcher; # can only be used once
128		701
129	sub new_timer {	702	sub new_timer {
130	$timer = AnyEvent->timer (after => 1, cb => sub {	703	$timer = AnyEvent->timer (after => 1, cb => sub {
135		708
136	new_timer; # create first timer	709	new_timer; # create first timer
137		710
138	$cv->wait; # wait until user enters /^q/i	711	$cv->wait; # wait until user enters /^q/i
139		712
		713	=head1 REAL-WORLD EXAMPLE
		714
		715	Consider the L<Net::FCP> module. It features (among others) the following
		716	API calls, which are to freenet what HTTP GET requests are to http:
		717
		718	my $data = $fcp->client_get ($url); # blocks
		719
		720	my $transaction = $fcp->txn_client_get ($url); # does not block
		721	$transaction->cb ( sub { ... } ); # set optional result callback
		722	my $data = $transaction->result; # possibly blocks
		723
		724	The C<client_get> method works like C<LWP::Simple::get>: it requests the
		725	given URL and waits till the data has arrived. It is defined to be:
		726
		727	sub client_get { $_[0]->txn_client_get ($_[1])->result }
		728
		729	And in fact is automatically generated. This is the blocking API of
		730	L<Net::FCP>, and it works as simple as in any other, similar, module.
		731
		732	More complicated is C<txn_client_get>: It only creates a transaction
		733	(completion, result, ...) object and initiates the transaction.
		734
		735	my $txn = bless { }, Net::FCP::Txn::;
		736
		737	It also creates a condition variable that is used to signal the completion
		738	of the request:
		739
		740	$txn->{finished} = AnyAvent->condvar;
		741
		742	It then creates a socket in non-blocking mode.
		743
		744	socket $txn->{fh}, ...;
		745	fcntl $txn->{fh}, F_SETFL, O_NONBLOCK;
		746	connect $txn->{fh}, ...
		747	and !$!{EWOULDBLOCK}
		748	and !$!{EINPROGRESS}
		749	and Carp::croak "unable to connect: $!\n";
		750
		751	Then it creates a write-watcher which gets called whenever an error occurs
		752	or the connection succeeds:
		753
		754	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w });
		755
		756	And returns this transaction object. The C<fh_ready_w> callback gets
		757	called as soon as the event loop detects that the socket is ready for
		758	writing.
		759
		760	The C<fh_ready_w> method makes the socket blocking again, writes the
		761	request data and replaces the watcher by a read watcher (waiting for reply
		762	data). The actual code is more complicated, but that doesn't matter for
		763	this example:
		764
		765	fcntl $txn->{fh}, F_SETFL, 0;
		766	syswrite $txn->{fh}, $txn->{request}
		767	or die "connection or write error";
		768	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
		769
		770	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
		771	result and signals any possible waiters that the request ahs finished:
		772
		773	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
		774
		775	if (end-of-file or data complete) {
		776	$txn->{result} = $txn->{buf};
		777	$txn->{finished}->broadcast;
		778	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
		779	}
		780
		781	The C<result> method, finally, just waits for the finished signal (if the
		782	request was already finished, it doesn't wait, of course, and returns the
		783	data:
		784
		785	$txn->{finished}->wait;
		786	return $txn->{result};
		787
		788	The actual code goes further and collects all errors (C<die>s, exceptions)
		789	that occured during request processing. The C<result> method detects
		790	whether an exception as thrown (it is stored inside the $txn object)
		791	and just throws the exception, which means connection errors and other
		792	problems get reported tot he code that tries to use the result, not in a
		793	random callback.
		794
		795	All of this enables the following usage styles:
		796
		797	1. Blocking:
		798
		799	my $data = $fcp->client_get ($url);
		800
		801	2. Blocking, but running in parallel:
		802
		803	my @datas = map $_->result,
		804	map $fcp->txn_client_get ($_),
		805	@urls;
		806
		807	Both blocking examples work without the module user having to know
		808	anything about events.
		809
		810	3a. Event-based in a main program, using any supported event module:
		811
		812	use EV;
		813
		814	$fcp->txn_client_get ($url)->cb (sub {
		815	my $txn = shift;
		816	my $data = $txn->result;
		817	...
		818	});
		819
		820	EV::loop;
		821
		822	3b. The module user could use AnyEvent, too:
		823
		824	use AnyEvent;
		825
		826	my $quit = AnyEvent->condvar;
		827
		828	$fcp->txn_client_get ($url)->cb (sub {
		829	...
		830	$quit->broadcast;
		831	});
		832
		833	$quit->wait;
		834
		835	=head1 FORK
		836
		837	Most event libraries are not fork-safe. The ones who are usually are
		838	because they are so inefficient. Only L<EV> is fully fork-aware.
		839
		840	If you have to fork, you must either do so I<before> creating your first
		841	watcher OR you must not use AnyEvent at all in the child.
		842
		843	=head1 SECURITY CONSIDERATIONS
		844
		845	AnyEvent can be forced to load any event model via
		846	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
		847	execute arbitrary code or directly gain access, it can easily be used to
		848	make the program hang or malfunction in subtle ways, as AnyEvent watchers
		849	will not be active when the program uses a different event model than
		850	specified in the variable.
		851
		852	You can make AnyEvent completely ignore this variable by deleting it
		853	before the first watcher gets created, e.g. with a C<BEGIN> block:
		854
		855	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
		856
		857	use AnyEvent;
		858
140	=head1 SEE ALSO	859	=head1 SEE ALSO
141		860
		861	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
142	L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>,	862	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
143	L<AnyEvent::Impl::Coro>,	863	L<Event::Lib>.
144	L<AnyEvent::Impl::Event>,
145	L<AnyEvent::Impl::Glib>,
146	L<AnyEvent::Impl::Tk>.
147		864
148	=head1	865	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
		866	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
		867	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>.
		868
		869	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
		870
		871	=head1 AUTHOR
		872
		873	Marc Lehmann <schmorp@schmorp.de>
		874	http://home.schmorp.de/
149		875
150	=cut	876	=cut
151		877
152	1	878	1
153		879

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.4 by root, Thu Dec 1 22:04:50 2005 UTC vs. Revision 1.55 by root, Wed Apr 23 11:25:42 2008 UTC

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Revision 1.55 by root, Wed Apr 23 11:25:42 2008 UTC