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

Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.5 by root, Sun Dec 4 09:44:32 2005 UTC vs.
Revision 1.59 by root, Thu Apr 24 08:38:13 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, Qt - 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->io (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	});
15
16	- only one io watcher per $fh and $poll type is allowed
17	(i.e. on a socket you can have one r + one w or one rw
18	watcher, not any more.
19
20	- AnyEvent will keep filehandles alive, so as long as the watcher exists,
21	the filehandle exists.
22		14
23	my $w = AnyEvent->timer (after => $seconds, cb => sub {	15	my $w = AnyEvent->timer (after => $seconds, cb => sub {
24	...	16	...
25	});	17	});
26		18
27	- io and time watchers get canceled whenever $w is destroyed, so keep a copy	19	my $w = AnyEvent->condvar; # stores whether a condition was flagged
28
29	- timers can only be used once and must be recreated for repeated operation
30
31	my $w = AnyEvent->condvar; # kind of main loop replacement
32	$w->wait; # enters main loop till $condvar gets ->broadcast	20	$w->wait; # enters "main loop" till $condvar gets ->broadcast
33	$w->broadcast; # wake up current and all future wait's	21	$w->broadcast; # wake up current and all future wait's
34		22
35	- condvars are used to give blocking behaviour when neccessary. Create	23	=head1 WHY YOU SHOULD USE THIS MODULE (OR NOT)
36	a condvar for any "request" or "event" your module might create, C<<	24
37	->broadcast >> it when the event happens and provide a function that calls	25	Glib, POE, IO::Async, Event... CPAN offers event models by the dozen
38	C<< ->wait >> for it. See the examples below.	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
39		71
40	=head1 DESCRIPTION	72	=head1 DESCRIPTION
41		73
42	L<AnyEvent> provides an identical interface to multiple event loops. This	74	L<AnyEvent> provides an identical interface to multiple event loops. This
43	allows module authors to utilizy an event loop without forcing module	75	allows module authors to utilise an event loop without forcing module
44	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
45	peacefully at any one time).	77	peacefully at any one time).
46		78
47	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>
48	module.	80	module.
49		81
50	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
51	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
52	loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is	84	the following modules is already loaded: L<Coro::EV>, L<Coro::Event>,
		85	L<EV>, L<Event>, L<Glib>, L<Tk>, L<Event::Lib>, L<Qt>. The first one
53	used. If none is found, the module tries to load these modules in the	86	found is used. If none are found, the module tries to load these modules
54	order given. The first one that could be successfully loaded will be	87	(excluding Event::Lib and Qt) in the order given. The first one that can
55	used. If still none could be found, it will issue an error.	88	be successfully loaded will be used. If, after this, still none could be
		89	found, AnyEvent will fall back to a pure-perl event loop, which is not
		90	very efficient, but should work everywhere.
		91
		92	Because AnyEvent first checks for modules that are already loaded, loading
		93	an event model explicitly before first using AnyEvent will likely make
		94	that model the default. For example:
		95
		96	use Tk;
		97	use AnyEvent;
		98
		99	# .. AnyEvent will likely default to Tk
		100
		101	The I<likely> means that, if any module loads another event model and
		102	starts using it, all bets are off. Maybe you should tell their authors to
		103	use AnyEvent so their modules work together with others seamlessly...
		104
		105	The pure-perl implementation of AnyEvent is called
		106	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
		107	explicitly.
		108
		109	=head1 WATCHERS
		110
		111	AnyEvent has the central concept of a I<watcher>, which is an object that
		112	stores relevant data for each kind of event you are waiting for, such as
		113	the callback to call, the filehandle to watch, etc.
		114
		115	These watchers are normal Perl objects with normal Perl lifetime. After
		116	creating a watcher it will immediately "watch" for events and invoke the
		117	callback when the event occurs (of course, only when the event model
		118	is in control).
		119
		120	To disable the watcher you have to destroy it (e.g. by setting the
		121	variable you store it in to C<undef> or otherwise deleting all references
		122	to it).
		123
		124	All watchers are created by calling a method on the C<AnyEvent> class.
		125
		126	Many watchers either are used with "recursion" (repeating timers for
		127	example), or need to refer to their watcher object in other ways.
		128
		129	An any way to achieve that is this pattern:
		130
		131	my $w; $w = AnyEvent->type (arg => value ..., cb => sub {
		132	# you can use $w here, for example to undef it
		133	undef $w;
		134	});
		135
		136	Note that C<my $w; $w => combination. This is necessary because in Perl,
		137	my variables are only visible after the statement in which they are
		138	declared.
		139
		140	=head2 IO WATCHERS
		141
		142	You can create an I/O watcher by calling the C<< AnyEvent->io >> method
		143	with the following mandatory key-value pairs as arguments:
		144
		145	C<fh> the Perl I<file handle> (I<not> file descriptor) to watch for
		146	events. C<poll> must be a string that is either C<r> or C<w>, which
		147	creates a watcher waiting for "r"eadable or "w"ritable events,
		148	respectively. C<cb> is the callback to invoke each time the file handle
		149	becomes ready.
		150
		151	As long as the I/O watcher exists it will keep the file descriptor or a
		152	copy of it alive/open.
		153
		154	It is not allowed to close a file handle as long as any watcher is active
		155	on the underlying file descriptor.
		156
		157	Some event loops issue spurious readyness notifications, so you should
		158	always use non-blocking calls when reading/writing from/to your file
		159	handles.
		160
		161	Example:
		162
		163	# wait for readability of STDIN, then read a line and disable the watcher
		164	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		165	chomp (my $input = <STDIN>);
		166	warn "read: $input\n";
		167	undef $w;
		168	});
		169
		170	=head2 TIME WATCHERS
		171
		172	You can create a time watcher by calling the C<< AnyEvent->timer >>
		173	method with the following mandatory arguments:
		174
		175	C<after> specifies after how many seconds (fractional values are
		176	supported) should the timer activate. C<cb> the callback to invoke in that
		177	case.
		178
		179	The timer callback will be invoked at most once: if you want a repeating
		180	timer you have to create a new watcher (this is a limitation by both Tk
		181	and Glib).
		182
		183	Example:
		184
		185	# fire an event after 7.7 seconds
		186	my $w = AnyEvent->timer (after => 7.7, cb => sub {
		187	warn "timeout\n";
		188	});
		189
		190	# to cancel the timer:
		191	undef $w;
		192
		193	Example 2:
		194
		195	# fire an event after 0.5 seconds, then roughly every second
		196	my $w;
		197
		198	my $cb = sub {
		199	# cancel the old timer while creating a new one
		200	$w = AnyEvent->timer (after => 1, cb => $cb);
		201	};
		202
		203	# start the "loop" by creating the first watcher
		204	$w = AnyEvent->timer (after => 0.5, cb => $cb);
		205
		206	=head3 TIMING ISSUES
		207
		208	There are two ways to handle timers: based on real time (relative, "fire
		209	in 10 seconds") and based on wallclock time (absolute, "fire at 12
		210	o'clock").
		211
		212	While most event loops expect timers to specified in a relative way, they
		213	use absolute time internally. This makes a difference when your clock
		214	"jumps", for example, when ntp decides to set your clock backwards from
		215	the wrong date of 2014-01-01 to 2008-01-01, a watcher that is supposed to
		216	fire "after" a second might actually take six years to finally fire.
		217
		218	AnyEvent cannot compensate for this. The only event loop that is conscious
		219	about these issues is L<EV>, which offers both relative (ev_timer, based
		220	on true relative time) and absolute (ev_periodic, based on wallclock time)
		221	timers.
		222
		223	AnyEvent always prefers relative timers, if available, matching the
		224	AnyEvent API.
		225
		226	=head2 SIGNAL WATCHERS
		227
		228	You can watch for signals using a signal watcher, C<signal> is the signal
		229	I<name> without any C<SIG> prefix, C<cb> is the Perl callback to
		230	be invoked whenever a signal occurs.
		231
		232	Multiple signal occurances can be clumped together into one callback
		233	invocation, and callback invocation will be synchronous. synchronous means
		234	that it might take a while until the signal gets handled by the process,
		235	but it is guarenteed not to interrupt any other callbacks.
		236
		237	The main advantage of using these watchers is that you can share a signal
		238	between multiple watchers.
		239
		240	This watcher might use C<%SIG>, so programs overwriting those signals
		241	directly will likely not work correctly.
		242
		243	Example: exit on SIGINT
		244
		245	my $w = AnyEvent->signal (signal => "INT", cb => sub { exit 1 });
		246
		247	=head2 CHILD PROCESS WATCHERS
		248
		249	You can also watch on a child process exit and catch its exit status.
		250
		251	The child process is specified by the C<pid> argument (if set to C<0>, it
		252	watches for any child process exit). The watcher will trigger as often
		253	as status change for the child are received. This works by installing a
		254	signal handler for C<SIGCHLD>. The callback will be called with the pid
		255	and exit status (as returned by waitpid).
		256
		257	Example: wait for pid 1333
		258
		259	my $w = AnyEvent->child (
		260	pid => 1333,
		261	cb => sub {
		262	my ($pid, $status) = @_;
		263	warn "pid $pid exited with status $status";
		264	},
		265	);
		266
		267	=head2 CONDITION VARIABLES
		268
		269	Condition variables can be created by calling the C<< AnyEvent->condvar >>
		270	method without any arguments.
		271
		272	A condition variable waits for a condition - precisely that the C<<
		273	->broadcast >> method has been called.
		274
		275	They are very useful to signal that a condition has been fulfilled, for
		276	example, if you write a module that does asynchronous http requests,
		277	then a condition variable would be the ideal candidate to signal the
		278	availability of results.
		279
		280	You can also use condition variables to block your main program until
		281	an event occurs - for example, you could C<< ->wait >> in your main
		282	program until the user clicks the Quit button in your app, which would C<<
		283	->broadcast >> the "quit" event.
		284
		285	Note that condition variables recurse into the event loop - if you have
		286	two pirces of code that call C<< ->wait >> in a round-robbin fashion, you
		287	lose. Therefore, condition variables are good to export to your caller, but
		288	you should avoid making a blocking wait yourself, at least in callbacks,
		289	as this asks for trouble.
		290
		291	This object has two methods:
56		292
57	=over 4	293	=over 4
58		294
		295	=item $cv->wait
		296
		297	Wait (blocking if necessary) until the C<< ->broadcast >> method has been
		298	called on c<$cv>, while servicing other watchers normally.
		299
		300	You can only wait once on a condition - additional calls will return
		301	immediately.
		302
		303	Not all event models support a blocking wait - some die in that case
		304	(programs might want to do that to stay interactive), so I<if you are
		305	using this from a module, never require a blocking wait>, but let the
		306	caller decide whether the call will block or not (for example, by coupling
		307	condition variables with some kind of request results and supporting
		308	callbacks so the caller knows that getting the result will not block,
		309	while still suppporting blocking waits if the caller so desires).
		310
		311	Another reason I<never> to C<< ->wait >> in a module is that you cannot
		312	sensibly have two C<< ->wait >>'s in parallel, as that would require
		313	multiple interpreters or coroutines/threads, none of which C<AnyEvent>
		314	can supply (the coroutine-aware backends L<AnyEvent::Impl::CoroEV> and
		315	L<AnyEvent::Impl::CoroEvent> explicitly support concurrent C<< ->wait >>'s
		316	from different coroutines, however).
		317
		318	=item $cv->broadcast
		319
		320	Flag the condition as ready - a running C<< ->wait >> and all further
		321	calls to C<wait> will (eventually) return after this method has been
		322	called. If nobody is waiting the broadcast will be remembered..
		323
		324	=back
		325
		326	Example:
		327
		328	# wait till the result is ready
		329	my $result_ready = AnyEvent->condvar;
		330
		331	# do something such as adding a timer
		332	# or socket watcher the calls $result_ready->broadcast
		333	# when the "result" is ready.
		334	# in this case, we simply use a timer:
		335	my $w = AnyEvent->timer (
		336	after => 1,
		337	cb => sub { $result_ready->broadcast },
		338	);
		339
		340	# this "blocks" (while handling events) till the watcher
		341	# calls broadcast
		342	$result_ready->wait;
		343
		344	=head1 GLOBAL VARIABLES AND FUNCTIONS
		345
		346	=over 4
		347
		348	=item $AnyEvent::MODEL
		349
		350	Contains C<undef> until the first watcher is being created. Then it
		351	contains the event model that is being used, which is the name of the
		352	Perl class implementing the model. This class is usually one of the
		353	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
		354	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
		355
		356	The known classes so far are:
		357
		358	AnyEvent::Impl::CoroEV based on Coro::EV, best choice.
		359	AnyEvent::Impl::CoroEvent based on Coro::Event, second best choice.
		360	AnyEvent::Impl::EV based on EV (an interface to libev, best choice).
		361	AnyEvent::Impl::Event based on Event, second best choice.
		362	AnyEvent::Impl::Glib based on Glib, third-best choice.
		363	AnyEvent::Impl::Tk based on Tk, very bad choice.
		364	AnyEvent::Impl::Perl pure-perl implementation, inefficient but portable.
		365	AnyEvent::Impl::Qt based on Qt, cannot be autoprobed (see its docs).
		366	AnyEvent::Impl::EventLib based on Event::Lib, leaks memory and worse.
		367
		368	=item AnyEvent::detect
		369
		370	Returns C<$AnyEvent::MODEL>, forcing autodetection of the event model
		371	if necessary. You should only call this function right before you would
		372	have created an AnyEvent watcher anyway, that is, as late as possible at
		373	runtime.
		374
		375	=back
		376
		377	=head1 WHAT TO DO IN A MODULE
		378
		379	As a module author, you should C<use AnyEvent> and call AnyEvent methods
		380	freely, but you should not load a specific event module or rely on it.
		381
		382	Be careful when you create watchers in the module body - AnyEvent will
		383	decide which event module to use as soon as the first method is called, so
		384	by calling AnyEvent in your module body you force the user of your module
		385	to load the event module first.
		386
		387	Never call C<< ->wait >> on a condition variable unless you I<know> that
		388	the C<< ->broadcast >> method has been called on it already. This is
		389	because it will stall the whole program, and the whole point of using
		390	events is to stay interactive.
		391
		392	It is fine, however, to call C<< ->wait >> when the user of your module
		393	requests it (i.e. if you create a http request object ad have a method
		394	called C<results> that returns the results, it should call C<< ->wait >>
		395	freely, as the user of your module knows what she is doing. always).
		396
		397	=head1 WHAT TO DO IN THE MAIN PROGRAM
		398
		399	There will always be a single main program - the only place that should
		400	dictate which event model to use.
		401
		402	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
		403	do anything special (it does not need to be event-based) and let AnyEvent
		404	decide which implementation to chose if some module relies on it.
		405
		406	If the main program relies on a specific event model. For example, in
		407	Gtk2 programs you have to rely on the Glib module. You should load the
		408	event module before loading AnyEvent or any module that uses it: generally
		409	speaking, you should load it as early as possible. The reason is that
		410	modules might create watchers when they are loaded, and AnyEvent will
		411	decide on the event model to use as soon as it creates watchers, and it
		412	might chose the wrong one unless you load the correct one yourself.
		413
		414	You can chose to use a rather inefficient pure-perl implementation by
		415	loading the C<AnyEvent::Impl::Perl> module, which gives you similar
		416	behaviour everywhere, but letting AnyEvent chose is generally better.
		417
59	=cut	418	=cut
60		419
61	package AnyEvent;	420	package AnyEvent;
62		421
63	no warnings;	422	no warnings;
64	use strict 'vars';	423	use strict;
		424
65	use Carp;	425	use Carp;
66		426
67	our $VERSION = 0.3;	427	our $VERSION = '3.2';
68	our $MODEL;	428	our $MODEL;
69		429
70	our $AUTOLOAD;	430	our $AUTOLOAD;
71	our @ISA;	431	our @ISA;
72		432
		433	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		434
		435	our @REGISTRY;
		436
73	my @models = (	437	my @models = (
74	[Coro => Coro::Event::],	438	[Coro::EV:: => AnyEvent::Impl::CoroEV::],
75	[Event => Event::],	439	[Coro::Event:: => AnyEvent::Impl::CoroEvent::],
76	[Glib => Glib::],	440	[EV:: => AnyEvent::Impl::EV::],
77	[Tk => Tk::],	441	[Event:: => AnyEvent::Impl::Event::],
		442	[Glib:: => AnyEvent::Impl::Glib::],
		443	[Tk:: => AnyEvent::Impl::Tk::],
		444	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
78	);	445	);
		446	my @models_detect = (
		447	[Qt:: => AnyEvent::Impl::Qt::], # requires special main program
		448	[Event::Lib:: => AnyEvent::Impl::EventLib::], # too buggy
		449	);
79		450
80	our %method = map +($_ => 1), qw(io timer condvar broadcast wait cancel DESTROY);	451	our %method = map +($_ => 1), qw(io timer signal child condvar broadcast wait one_event DESTROY);
81		452
82	sub AUTOLOAD {	453	sub detect() {
83	$AUTOLOAD =~ s/.*://;
84
85	$method{$AUTOLOAD}
86	or croak "$AUTOLOAD: not a valid method for AnyEvent objects";
87
88	unless ($MODEL) {	454	unless ($MODEL) {
89	# check for already loaded models	455	no strict 'refs';
90	for (@models) {	456
91	my ($model, $package) = @$_;	457	if ($ENV{PERL_ANYEVENT_MODEL} =~ /^([a-zA-Z]+)$/) {
92	if (scalar keys %{ *{"$package\::"} }) {	458	my $model = "AnyEvent::Impl::$1";
93	eval "require AnyEvent::Impl::$model";	459	if (eval "require $model") {
94	last if $MODEL;	460	$MODEL = $model;
		461	warn "AnyEvent: loaded model '$model' (forced by \$PERL_ANYEVENT_MODEL), using it.\n" if $verbose > 1;
95	}	462	}
96	}	463	}
97		464
		465	# check for already loaded models
98	unless ($MODEL) {	466	unless ($MODEL) {
99	# try to load a model	467	for (@REGISTRY, @models, @models_detect) {
100
101	for (@models) {
102	my ($model, $package) = @$_;	468	my ($package, $model) = @$_;
103	eval "require AnyEvent::Impl::$model";	469	if (${"$package\::VERSION"} > 0) {
104	last if $MODEL;	470	if (eval "require $model") {
		471	$MODEL = $model;
		472	warn "AnyEvent: autodetected model '$model', using it.\n" if $verbose > 1;
		473	last;
		474	}
		475	}
105	}	476	}
106		477
		478	unless ($MODEL) {
		479	# try to load a model
		480
		481	for (@REGISTRY, @models) {
		482	my ($package, $model) = @$_;
		483	if (eval "require $package"
		484	and ${"$package\::VERSION"} > 0
		485	and eval "require $model") {
		486	$MODEL = $model;
		487	warn "AnyEvent: autoprobed model '$model', using it.\n" if $verbose > 1;
		488	last;
		489	}
		490	}
		491
107	$MODEL	492	$MODEL
108	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk.";	493	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.";
		494	}
109	}	495	}
		496
		497	unshift @ISA, $MODEL;
		498	push @{"$MODEL\::ISA"}, "AnyEvent::Base";
110	}	499	}
111		500
112	@ISA = $MODEL;	501	$MODEL
		502	}
		503
		504	sub AUTOLOAD {
		505	(my $func = $AUTOLOAD) =~ s/.*://;
		506
		507	$method{$func}
		508	or croak "$func: not a valid method for AnyEvent objects";
		509
		510	detect unless $MODEL;
113		511
114	my $class = shift;	512	my $class = shift;
115	$class->$AUTOLOAD (@_);	513	$class->$func (@_);
116	}	514	}
		515
		516	package AnyEvent::Base;
		517
		518	# default implementation for ->condvar, ->wait, ->broadcast
		519
		520	sub condvar {
		521	bless \my $flag, "AnyEvent::Base::CondVar"
		522	}
		523
		524	sub AnyEvent::Base::CondVar::broadcast {
		525	${$_[0]}++;
		526	}
		527
		528	sub AnyEvent::Base::CondVar::wait {
		529	AnyEvent->one_event while !${$_[0]};
		530	}
		531
		532	# default implementation for ->signal
		533
		534	our %SIG_CB;
		535
		536	sub signal {
		537	my (undef, %arg) = @_;
		538
		539	my $signal = uc $arg{signal}
		540	or Carp::croak "required option 'signal' is missing";
		541
		542	$SIG_CB{$signal}{$arg{cb}} = $arg{cb};
		543	$SIG{$signal} \|\|= sub {
		544	$_->() for values %{ $SIG_CB{$signal} \|\| {} };
		545	};
		546
		547	bless [$signal, $arg{cb}], "AnyEvent::Base::Signal"
		548	}
		549
		550	sub AnyEvent::Base::Signal::DESTROY {
		551	my ($signal, $cb) = @{$_[0]};
		552
		553	delete $SIG_CB{$signal}{$cb};
		554
		555	$SIG{$signal} = 'DEFAULT' unless keys %{ $SIG_CB{$signal} };
		556	}
		557
		558	# default implementation for ->child
		559
		560	our %PID_CB;
		561	our $CHLD_W;
		562	our $CHLD_DELAY_W;
		563	our $PID_IDLE;
		564	our $WNOHANG;
		565
		566	sub _child_wait {
		567	while (0 < (my $pid = waitpid -1, $WNOHANG)) {
		568	$_->($pid, $?) for (values %{ $PID_CB{$pid} \|\| {} }),
		569	(values %{ $PID_CB{0} \|\| {} });
		570	}
		571
		572	undef $PID_IDLE;
		573	}
		574
		575	sub _sigchld {
		576	# make sure we deliver these changes "synchronous" with the event loop.
		577	$CHLD_DELAY_W \|\|= AnyEvent->timer (after => 0, cb => sub {
		578	undef $CHLD_DELAY_W;
		579	&_child_wait;
		580	});
		581	}
		582
		583	sub child {
		584	my (undef, %arg) = @_;
		585
		586	defined (my $pid = $arg{pid} + 0)
		587	or Carp::croak "required option 'pid' is missing";
		588
		589	$PID_CB{$pid}{$arg{cb}} = $arg{cb};
		590
		591	unless ($WNOHANG) {
		592	$WNOHANG = eval { require POSIX; &POSIX::WNOHANG } \|\| 1;
		593	}
		594
		595	unless ($CHLD_W) {
		596	$CHLD_W = AnyEvent->signal (signal => 'CHLD', cb => \&_sigchld);
		597	# child could be a zombie already, so make at least one round
		598	&_sigchld;
		599	}
		600
		601	bless [$pid, $arg{cb}], "AnyEvent::Base::Child"
		602	}
		603
		604	sub AnyEvent::Base::Child::DESTROY {
		605	my ($pid, $cb) = @{$_[0]};
		606
		607	delete $PID_CB{$pid}{$cb};
		608	delete $PID_CB{$pid} unless keys %{ $PID_CB{$pid} };
		609
		610	undef $CHLD_W unless keys %PID_CB;
		611	}
		612
		613	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
		614
		615	This is an advanced topic that you do not normally need to use AnyEvent in
		616	a module. This section is only of use to event loop authors who want to
		617	provide AnyEvent compatibility.
		618
		619	If you need to support another event library which isn't directly
		620	supported by AnyEvent, you can supply your own interface to it by
		621	pushing, before the first watcher gets created, the package name of
		622	the event module and the package name of the interface to use onto
		623	C<@AnyEvent::REGISTRY>. You can do that before and even without loading
		624	AnyEvent, so it is reasonably cheap.
		625
		626	Example:
		627
		628	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
		629
		630	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
		631	package/class when it finds the C<urxvt> package/module is already loaded.
		632
		633	When AnyEvent is loaded and asked to find a suitable event model, it
		634	will first check for the presence of urxvt by trying to C<use> the
		635	C<urxvt::anyevent> module.
		636
		637	The class should provide implementations for all watcher types. See
		638	L<AnyEvent::Impl::EV> (source code), L<AnyEvent::Impl::Glib> (Source code)
		639	and so on for actual examples. Use C<perldoc -m AnyEvent::Impl::Glib> to
		640	see the sources.
		641
		642	If you don't provide C<signal> and C<child> watchers than AnyEvent will
		643	provide suitable (hopefully) replacements.
		644
		645	The above example isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
		646	terminal emulator uses the above line as-is. An interface isn't included
		647	in AnyEvent because it doesn't make sense outside the embedded interpreter
		648	inside I<rxvt-unicode>, and it is updated and maintained as part of the
		649	I<rxvt-unicode> distribution.
		650
		651	I<rxvt-unicode> also cheats a bit by not providing blocking access to
		652	condition variables: code blocking while waiting for a condition will
		653	C<die>. This still works with most modules/usages, and blocking calls must
		654	not be done in an interactive application, so it makes sense.
		655
		656	=head1 ENVIRONMENT VARIABLES
		657
		658	The following environment variables are used by this module:
		659
		660	=over 4
		661
		662	=item C<PERL_ANYEVENT_VERBOSE>
		663
		664	When set to C<2> or higher, cause AnyEvent to report to STDERR which event
		665	model it chooses.
		666
		667	=item C<PERL_ANYEVENT_MODEL>
		668
		669	This can be used to specify the event model to be used by AnyEvent, before
		670	autodetection and -probing kicks in. It must be a string consisting
		671	entirely of ASCII letters. The string C<AnyEvent::Impl::> gets prepended
		672	and the resulting module name is loaded and if the load was successful,
		673	used as event model. If it fails to load AnyEvent will proceed with
		674	autodetection and -probing.
		675
		676	This functionality might change in future versions.
		677
		678	For example, to force the pure perl model (L<AnyEvent::Impl::Perl>) you
		679	could start your program like this:
		680
		681	PERL_ANYEVENT_MODEL=Perl perl ...
117		682
118	=back	683	=back
119		684
120	=head1 EXAMPLE	685	=head1 EXAMPLE PROGRAM
121		686
122	The following program uses an io watcher to read data from stdin, a timer	687	The following program uses an IO watcher to read data from STDIN, a timer
123	to display a message once per second, and a condvar to exit the program	688	to display a message once per second, and a condition variable to quit the
124	when the user enters quit:	689	program when the user enters quit:
125		690
126	use AnyEvent;	691	use AnyEvent;
127		692
128	my $cv = AnyEvent->condvar;	693	my $cv = AnyEvent->condvar;
129		694
130	my $io_watcher = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {	695	my $io_watcher = AnyEvent->io (
		696	fh => \*STDIN,
		697	poll => 'r',
		698	cb => sub {
131	warn "io event <$_[0]>\n"; # will always output <r>	699	warn "io event <$_[0]>\n"; # will always output <r>
132	chomp (my $input = <STDIN>); # read a line	700	chomp (my $input = <STDIN>); # read a line
133	warn "read: $input\n"; # output what has been read	701	warn "read: $input\n"; # output what has been read
134	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i	702	$cv->broadcast if $input =~ /^q/i; # quit program if /^q/i
		703	},
135	});	704	);
136		705
137	my $time_watcher; # can only be used once	706	my $time_watcher; # can only be used once
138		707
139	sub new_timer {	708	sub new_timer {
140	$timer = AnyEvent->timer (after => 1, cb => sub {	709	$timer = AnyEvent->timer (after => 1, cb => sub {
183	connect $txn->{fh}, ...	752	connect $txn->{fh}, ...
184	and !$!{EWOULDBLOCK}	753	and !$!{EWOULDBLOCK}
185	and !$!{EINPROGRESS}	754	and !$!{EINPROGRESS}
186	and Carp::croak "unable to connect: $!\n";	755	and Carp::croak "unable to connect: $!\n";
187		756
188	Then it creates a write-watcher which gets called wehnever an error occurs	757	Then it creates a write-watcher which gets called whenever an error occurs
189	or the connection succeeds:	758	or the connection succeeds:
190		759
191	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w });	760	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w });
192		761
193	And returns this transaction object. The C<fh_ready_w> callback gets	762	And returns this transaction object. The C<fh_ready_w> callback gets
…		…
210	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};	779	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
211		780
212	if (end-of-file or data complete) {	781	if (end-of-file or data complete) {
213	$txn->{result} = $txn->{buf};	782	$txn->{result} = $txn->{buf};
214	$txn->{finished}->broadcast;	783	$txn->{finished}->broadcast;
		784	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
215	}	785	}
216		786
217	The C<result> method, finally, just waits for the finished signal (if the	787	The C<result> method, finally, just waits for the finished signal (if the
218	request was already finished, it doesn't wait, of course, and returns the	788	request was already finished, it doesn't wait, of course, and returns the
219	data:	789	data:
220		790
221	$txn->{finished}->wait;	791	$txn->{finished}->wait;
222	return $txn->{buf};	792	return $txn->{result};
223		793
224	The actual code goes further and collects all errors (C<die>s, exceptions)	794	The actual code goes further and collects all errors (C<die>s, exceptions)
225	that occured during request processing. The C<result> method detects	795	that occured during request processing. The C<result> method detects
226	wether an exception as thrown (it is stored inside the $txn object)	796	whether an exception as thrown (it is stored inside the $txn object)
227	and just throws the exception, which means connection errors and other	797	and just throws the exception, which means connection errors and other
228	problems get reported tot he code that tries to use the result, not in a	798	problems get reported tot he code that tries to use the result, not in a
229	random callback.	799	random callback.
230		800
231	All of this enables the following usage styles:	801	All of this enables the following usage styles:
232		802
233	1. Blocking:	803	1. Blocking:
234		804
235	my $data = $fcp->client_get ($url);	805	my $data = $fcp->client_get ($url);
236		806
237	2. Blocking, but parallelizing:	807	2. Blocking, but running in parallel:
238		808
239	my @datas = map $_->result,	809	my @datas = map $_->result,
240	map $fcp->txn_client_get ($_),	810	map $fcp->txn_client_get ($_),
241	@urls;	811	@urls;
242		812
243	Both blocking examples work without the module user having to know	813	Both blocking examples work without the module user having to know
244	anything about events.	814	anything about events.
245		815
246	3a. Event-based in a main program, using any support Event module:	816	3a. Event-based in a main program, using any supported event module:
247		817
248	use Event;	818	use EV;
249		819
250	$fcp->txn_client_get ($url)->cb (sub {	820	$fcp->txn_client_get ($url)->cb (sub {
251	my $txn = shift;	821	my $txn = shift;
252	my $data = $txn->result;	822	my $data = $txn->result;
253	...	823	...
254	});	824	});
255		825
256	Event::loop;	826	EV::loop;
257		827
258	3b. The module user could use AnyEvent, too:	828	3b. The module user could use AnyEvent, too:
259		829
260	use AnyEvent;	830	use AnyEvent;
261		831
…		…
266	$quit->broadcast;	836	$quit->broadcast;
267	});	837	});
268		838
269	$quit->wait;	839	$quit->wait;
270		840
		841	=head1 FORK
		842
		843	Most event libraries are not fork-safe. The ones who are usually are
		844	because they are so inefficient. Only L<EV> is fully fork-aware.
		845
		846	If you have to fork, you must either do so I<before> creating your first
		847	watcher OR you must not use AnyEvent at all in the child.
		848
		849	=head1 SECURITY CONSIDERATIONS
		850
		851	AnyEvent can be forced to load any event model via
		852	$ENV{PERL_ANYEVENT_MODEL}. While this cannot (to my knowledge) be used to
		853	execute arbitrary code or directly gain access, it can easily be used to
		854	make the program hang or malfunction in subtle ways, as AnyEvent watchers
		855	will not be active when the program uses a different event model than
		856	specified in the variable.
		857
		858	You can make AnyEvent completely ignore this variable by deleting it
		859	before the first watcher gets created, e.g. with a C<BEGIN> block:
		860
		861	BEGIN { delete $ENV{PERL_ANYEVENT_MODEL} }
		862
		863	use AnyEvent;
		864
271	=head1 SEE ALSO	865	=head1 SEE ALSO
272		866
273	Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>.	867	Event modules: L<Coro::EV>, L<EV>, L<EV::Glib>, L<Glib::EV>,
		868	L<Coro::Event>, L<Event>, L<Glib::Event>, L<Glib>, L<Coro>, L<Tk>,
		869	L<Event::Lib>, L<Qt>.
274		870
		871	Implementations: L<AnyEvent::Impl::CoroEV>, L<AnyEvent::Impl::EV>,
275	Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>.	872	L<AnyEvent::Impl::CoroEvent>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>,
		873	L<AnyEvent::Impl::Tk>, L<AnyEvent::Impl::Perl>, L<AnyEvent::Impl::EventLib>,
		874	L<AnyEvent::Impl::Qt>.
276		875
277	Nontrivial usage example: L<Net::FCP>.	876	Nontrivial usage examples: L<Net::FCP>, L<Net::XMPP2>.
278		877
279	=head1	878	=head1 AUTHOR
		879
		880	Marc Lehmann <schmorp@schmorp.de>
		881	http://home.schmorp.de/
280		882
281	=cut	883	=cut
282		884
283	1	885	1
284		886

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Comparing AnyEvent/lib/AnyEvent.pm (file contents): Revision 1.5 by root, Sun Dec 4 09:44:32 2005 UTC vs. Revision 1.59 by root, Thu Apr 24 08:38:13 2008 UTC

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Comparing AnyEvent/lib/AnyEvent.pm (file contents):
Revision 1.5 by root, Sun Dec 4 09:44:32 2005 UTC vs.
Revision 1.59 by root, Thu Apr 24 08:38:13 2008 UTC