[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 1.17 by root, Fri Nov 24 14:40:13 2006 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	Event, Coro, Glib, Tk, Perl - 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 wether 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
29		22
30	=head1 DESCRIPTION	23	=head1 DESCRIPTION
31		24
32	L<AnyEvent> provides an identical interface to multiple event loops. This	25	L<AnyEvent> provides an identical interface to multiple event loops. This
33	allows module authors to utilizy an event loop without forcing module	26	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	27	users to use the same event loop (as only a single event loop can coexist
35	peacefully at any one time).	28	peacefully at any one time).
36		29
37	The interface itself is vaguely similar but not identical to the Event	30	The interface itself is vaguely similar but not identical to the Event
38	module.	31	module.
40	On the first call of any method, the module tries to detect the currently	33	On the first call of any method, the module tries to detect the currently
41	loaded event loop by probing wether any of the following modules is	34	loaded event loop by probing wether any of the following modules is
42	loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is	35	loaded: L<Coro::Event>, L<Event>, L<Glib>, L<Tk>. The first one found is
43	used. If none is found, the module tries to load these modules in the	36	used. If none is found, the module tries to load these modules in the
44	order given. The first one that could be successfully loaded will be	37	order given. The first one that could be successfully loaded will be
45	used. If still none could be found, it will issue an error.	38	used. If still none could be found, AnyEvent will fall back to a pure-perl
		39	event loop, which is also not very efficient.
		40
		41	Because AnyEvent first checks for modules that are already loaded, loading
		42	an Event model explicitly before first using AnyEvent will likely make
		43	that model the default. For example:
		44
		45	use Tk;
		46	use AnyEvent;
		47
		48	# .. AnyEvent will likely default to Tk
		49
		50	The pure-perl implementation of AnyEvent is called
		51	C<AnyEvent::Impl::Perl>. Like other event modules you can load it
		52	explicitly.
		53
		54	=head1 WATCHERS
		55
		56	AnyEvent has the central concept of a I<watcher>, which is an object that
		57	stores relevant data for each kind of event you are waiting for, such as
		58	the callback to call, the filehandle to watch, etc.
		59
		60	These watchers are normal Perl objects with normal Perl lifetime. After
		61	creating a watcher it will immediately "watch" for events and invoke
		62	the callback. To disable the watcher you have to destroy it (e.g. by
		63	setting the variable that stores it to C<undef> or otherwise deleting all
		64	references to it).
		65
		66	All watchers are created by calling a method on the C<AnyEvent> class.
		67
		68	=head2 IO WATCHERS
		69
		70	You can create I/O watcher by calling the C<< AnyEvent->io >> method with
		71	the following mandatory arguments:
		72
		73	C<fh> the Perl I<filehandle> (not filedescriptor) to watch for
		74	events. C<poll> must be a string that is either C<r> or C<w>, that creates
		75	a watcher waiting for "r"eadable or "w"ritable events. C<cb> teh callback
		76	to invoke everytime the filehandle becomes ready.
		77
		78	Only one io watcher per C<fh> and C<poll> combination is allowed (i.e. on
		79	a socket you can have one r + one w, not any more (limitation comes from
		80	Tk - if you are sure you are not using Tk this limitation is gone).
		81
		82	Filehandles will be kept alive, so as long as the watcher exists, the
		83	filehandle exists, too.
		84
		85	Example:
		86
		87	# wait for readability of STDIN, then read a line and disable the watcher
		88	my $w; $w = AnyEvent->io (fh => \*STDIN, poll => 'r', cb => sub {
		89	chomp (my $input = <STDIN>);
		90	warn "read: $input\n";
		91	undef $w;
		92	});
		93
		94	=head2 TIMER WATCHERS
		95
		96	You can create a timer watcher by calling the C<< AnyEvent->timer >>
		97	method with the following mandatory arguments:
		98
		99	C<after> after how many seconds (fractions are supported) should the timer
		100	activate. C<cb> the callback to invoke.
		101
		102	The timer callback will be invoked at most once: if you want a repeating
		103	timer you have to create a new watcher (this is a limitation by both Tk
		104	and Glib).
		105
		106	Example:
		107
		108	# fire an event after 7.7 seconds
		109	my $w = AnyEvent->timer (after => 7.7, cb => sub {
		110	warn "timeout\n";
		111	});
		112
		113	# to cancel the timer:
		114	undef $w
		115
		116	=head2 CONDITION WATCHERS
		117
		118	Condition watchers can be created by calling the C<< AnyEvent->condvar >>
		119	method without any arguments.
		120
		121	A condition watcher watches for a condition - precisely that the C<<
		122	->broadcast >> method has been called.
		123
		124	The watcher has only two methods:
46		125
47	=over 4	126	=over 4
		127
		128	=item $cv->wait
		129
		130	Wait (blocking if necessary) until the C<< ->broadcast >> method has been
		131	called on c<$cv>, while servicing other watchers normally.
		132
		133	Not all event models support a blocking wait - some die in that case, so
		134	if you are using this from a module, never require a blocking wait, but
		135	let the caller decide wether the call will block or not (for example,
		136	by coupling condition variables with some kind of request results and
		137	supporting callbacks so the caller knows that getting the result will not
		138	block, while still suppporting blockign waits if the caller so desires).
		139
		140	You can only wait once on a condition - additional calls will return
		141	immediately.
		142
		143	=item $cv->broadcast
		144
		145	Flag the condition as ready - a running C<< ->wait >> and all further
		146	calls to C<wait> will return after this method has been called. If nobody
		147	is waiting the broadcast will be remembered..
		148
		149	Example:
		150
		151	# wait till the result is ready
		152	my $result_ready = AnyEvent->condvar;
		153
		154	# do something such as adding a timer
		155	# or socket watcher the calls $result_ready->broadcast
		156	# when the "result" is ready.
		157
		158	$result_ready->wait;
		159
		160	=back
		161
		162	=head1 GLOBALS
		163
		164	=over 4
		165
		166	=item $AnyEvent::MODEL
		167
		168	Contains C<undef> until the first watcher is being created. Then it
		169	contains the event model that is being used, which is the name of the
		170	Perl class implementing the model. This class is usually one of the
		171	C<AnyEvent::Impl:xxx> modules, but can be any other class in the case
		172	AnyEvent has been extended at runtime (e.g. in I<rxvt-unicode>).
		173
		174	The known classes so far are:
		175
		176	AnyEvent::Impl::Coro based on Coro::Event, best choise.
		177	AnyEvent::Impl::Event based on Event, also best choice :)
		178	AnyEvent::Impl::Glib based on Glib, second-best choice.
		179	AnyEvent::Impl::Tk based on Tk, very bad choice.
		180	AnyEvent::Impl::Perl pure-perl implementation, inefficient.
		181
		182	=back
		183
		184	=head1 WHAT TO DO IN A MODULE
		185
		186	As a module author, you should "use AnyEvent" and call AnyEvent methods
		187	freely, but you should not load a specific event module or rely on it.
		188
		189	Be careful when you create watchers in the module body - Anyevent will
		190	decide which event module to use as soon as the first method is called, so
		191	by calling AnyEvent in your module body you force the user of your module
		192	to load the event module first.
		193
		194	=head1 WHAT TO DO IN THE MAIN PROGRAM
		195
		196	There will always be a single main program - the only place that should
		197	dictate which event model to use.
		198
		199	If it doesn't care, it can just "use AnyEvent" and use it itself, or not
		200	do anything special and let AnyEvent decide which implementation to chose.
		201
		202	If the main program relies on a specific event model (for example, in Gtk2
		203	programs you have to rely on either Glib or Glib::Event), you should load
		204	it before loading AnyEvent or any module that uses it, generally, as early
		205	as possible. The reason is that modules might create watchers when they
		206	are loaded, and AnyEvent will decide on the event model to use as soon as
		207	it creates watchers, and it might chose the wrong one unless you load the
		208	correct one yourself.
		209
		210	You can chose to use a rather inefficient pure-perl implementation by
		211	loading the C<AnyEvent::Impl::Perl> module, but letting AnyEvent chose is
		212	generally better.
48		213
49	=cut	214	=cut
50		215
51	package AnyEvent;	216	package AnyEvent;
52		217
53	no warnings;	218	no warnings;
54	use strict 'vars';	219	use strict 'vars';
55	use Carp;	220	use Carp;
56		221
57	our $VERSION = 0.2;	222	our $VERSION = '2.1';
58	our $MODEL;	223	our $MODEL;
59		224
60	our $AUTOLOAD;	225	our $AUTOLOAD;
61	our @ISA;	226	our @ISA;
62		227
		228	our $verbose = $ENV{PERL_ANYEVENT_VERBOSE}*1;
		229
		230	our @REGISTRY;
		231
63	my @models = (	232	my @models = (
64	[Coro => Coro::Event::],	233	[Coro::Event:: => AnyEvent::Impl::Coro::],
65	[Event => Event::],	234	[Event:: => AnyEvent::Impl::Event::],
66	[Glib => Glib::],	235	[Glib:: => AnyEvent::Impl::Glib::],
67	[Tk => Tk::],	236	[Tk:: => AnyEvent::Impl::Tk::],
		237	[AnyEvent::Impl::Perl:: => AnyEvent::Impl::Perl::],
68	);	238	);
69		239
70	our %method = map +($_ => 1), qw(io timer condvar broadcast wait cancel DESTROY);	240	our %method = map +($_ => 1), qw(io timer condvar broadcast wait DESTROY);
71		241
72	sub AUTOLOAD {	242	sub AUTOLOAD {
73	$AUTOLOAD =~ s/.*://;	243	$AUTOLOAD =~ s/.*://;
74		244
75	$method{$AUTOLOAD}	245	$method{$AUTOLOAD}
76	or croak "$AUTOLOAD: not a valid method for AnyEvent objects";	246	or croak "$AUTOLOAD: not a valid method for AnyEvent objects";
77		247
78	unless ($MODEL) {	248	unless ($MODEL) {
79	# check for already loaded models	249	# check for already loaded models
80	for (@models) {	250	for (@REGISTRY, @models) {
81	my ($model, $package) = @$_;	251	my ($package, $model) = @$_;
82	if (scalar keys %{ *{"$package\::"} }) {	252	if (${"$package\::VERSION"} > 0) {
83	eval "require AnyEvent::Impl::$model";	253	if (eval "require $model") {
84	last if $MODEL;	254	$MODEL = $model;
		255	warn "AnyEvent: found model '$model', using it.\n" if $verbose > 1;
		256	last;
		257	}
85	}	258	}
86	}	259	}
87		260
88	unless ($MODEL) {	261	unless ($MODEL) {
89	# try to load a model	262	# try to load a model
90		263
91	for (@models) {	264	for (@REGISTRY, @models) {
92	my ($model, $package) = @$_;	265	my ($package, $model) = @$_;
93	eval "require AnyEvent::Impl::$model";	266	if (eval "require $model") {
94	last if $MODEL;	267	$MODEL = $model;
		268	warn "AnyEvent: autoprobed and loaded model '$model', using it.\n" if $verbose > 1;
		269	last;
		270	}
95	}	271	}
96		272
97	$MODEL	273	$MODEL
98	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk.";	274	or die "No event module selected for AnyEvent and autodetect failed. Install any one of these modules: Coro, Event, Glib or Tk.";
99	}	275	}
…		…
103		279
104	my $class = shift;	280	my $class = shift;
105	$class->$AUTOLOAD (@_);	281	$class->$AUTOLOAD (@_);
106	}	282	}
107		283
108	=back	284	=head1 SUPPLYING YOUR OWN EVENT MODEL INTERFACE
		285
		286	If you need to support another event library which isn't directly
		287	supported by AnyEvent, you can supply your own interface to it by
		288	pushing, before the first watcher gets created, the package name of
		289	the event module and the package name of the interface to use onto
		290	C<@AnyEvent::REGISTRY>. You can do that before and even without loading
		291	AnyEvent.
		292
		293	Example:
		294
		295	push @AnyEvent::REGISTRY, [urxvt => urxvt::anyevent::];
		296
		297	This tells AnyEvent to (literally) use the C<urxvt::anyevent::>
		298	package/class when it finds the C<urxvt> package/module is loaded. When
		299	AnyEvent is loaded and asked to find a suitable event model, it will
		300	first check for the presence of urxvt.
		301
		302	The class should prove implementations for all watcher types (see
		303	L<AnyEvent::Impl::Event> (source code), L<AnyEvent::Impl::Glib>
		304	(Source code) and so on for actual examples, use C<perldoc -m
		305	AnyEvent::Impl::Glib> to see the sources).
		306
		307	The above isn't fictitious, the I<rxvt-unicode> (a.k.a. urxvt)
		308	uses the above line as-is. An interface isn't included in AnyEvent
		309	because it doesn't make sense outside the embedded interpreter inside
		310	I<rxvt-unicode>, and it is updated and maintained as part of the
		311	I<rxvt-unicode> distribution.
		312
		313	I<rxvt-unicode> also cheats a bit by not providing blocking access to
		314	condition variables: code blocking while waiting for a condition will
		315	C<die>. This still works with most modules/usages, and blocking calls must
		316	not be in an interactive appliation, so it makes sense.
		317
		318	=head1 ENVIRONMENT VARIABLES
		319
		320	The following environment variables are used by this module:
		321
		322	C<PERL_ANYEVENT_VERBOSE> when set to C<2> or higher, reports which event
		323	model gets used.
109		324
110	=head1 EXAMPLE	325	=head1 EXAMPLE
111		326
112	The following program uses an io watcher to read data from stdin, a timer	327	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	328	to display a message once per second, and a condvar to exit the program
…		…
135		350
136	new_timer; # create first timer	351	new_timer; # create first timer
137		352
138	$cv->wait; # wait until user enters /^q/i	353	$cv->wait; # wait until user enters /^q/i
139		354
		355	=head1 REAL-WORLD EXAMPLE
		356
		357	Consider the L<Net::FCP> module. It features (among others) the following
		358	API calls, which are to freenet what HTTP GET requests are to http:
		359
		360	my $data = $fcp->client_get ($url); # blocks
		361
		362	my $transaction = $fcp->txn_client_get ($url); # does not block
		363	$transaction->cb ( sub { ... } ); # set optional result callback
		364	my $data = $transaction->result; # possibly blocks
		365
		366	The C<client_get> method works like C<LWP::Simple::get>: it requests the
		367	given URL and waits till the data has arrived. It is defined to be:
		368
		369	sub client_get { $_[0]->txn_client_get ($_[1])->result }
		370
		371	And in fact is automatically generated. This is the blocking API of
		372	L<Net::FCP>, and it works as simple as in any other, similar, module.
		373
		374	More complicated is C<txn_client_get>: It only creates a transaction
		375	(completion, result, ...) object and initiates the transaction.
		376
		377	my $txn = bless { }, Net::FCP::Txn::;
		378
		379	It also creates a condition variable that is used to signal the completion
		380	of the request:
		381
		382	$txn->{finished} = AnyAvent->condvar;
		383
		384	It then creates a socket in non-blocking mode.
		385
		386	socket $txn->{fh}, ...;
		387	fcntl $txn->{fh}, F_SETFL, O_NONBLOCK;
		388	connect $txn->{fh}, ...
		389	and !$!{EWOULDBLOCK}
		390	and !$!{EINPROGRESS}
		391	and Carp::croak "unable to connect: $!\n";
		392
		393	Then it creates a write-watcher which gets called whenever an error occurs
		394	or the connection succeeds:
		395
		396	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'w', cb => sub { $txn->fh_ready_w });
		397
		398	And returns this transaction object. The C<fh_ready_w> callback gets
		399	called as soon as the event loop detects that the socket is ready for
		400	writing.
		401
		402	The C<fh_ready_w> method makes the socket blocking again, writes the
		403	request data and replaces the watcher by a read watcher (waiting for reply
		404	data). The actual code is more complicated, but that doesn't matter for
		405	this example:
		406
		407	fcntl $txn->{fh}, F_SETFL, 0;
		408	syswrite $txn->{fh}, $txn->{request}
		409	or die "connection or write error";
		410	$txn->{w} = AnyEvent->io (fh => $txn->{fh}, poll => 'r', cb => sub { $txn->fh_ready_r });
		411
		412	Again, C<fh_ready_r> waits till all data has arrived, and then stores the
		413	result and signals any possible waiters that the request ahs finished:
		414
		415	sysread $txn->{fh}, $txn->{buf}, length $txn->{$buf};
		416
		417	if (end-of-file or data complete) {
		418	$txn->{result} = $txn->{buf};
		419	$txn->{finished}->broadcast;
		420	$txb->{cb}->($txn) of $txn->{cb}; # also call callback
		421	}
		422
		423	The C<result> method, finally, just waits for the finished signal (if the
		424	request was already finished, it doesn't wait, of course, and returns the
		425	data:
		426
		427	$txn->{finished}->wait;
		428	return $txn->{result};
		429
		430	The actual code goes further and collects all errors (C<die>s, exceptions)
		431	that occured during request processing. The C<result> method detects
		432	wether an exception as thrown (it is stored inside the $txn object)
		433	and just throws the exception, which means connection errors and other
		434	problems get reported tot he code that tries to use the result, not in a
		435	random callback.
		436
		437	All of this enables the following usage styles:
		438
		439	1. Blocking:
		440
		441	my $data = $fcp->client_get ($url);
		442
		443	2. Blocking, but parallelizing:
		444
		445	my @datas = map $_->result,
		446	map $fcp->txn_client_get ($_),
		447	@urls;
		448
		449	Both blocking examples work without the module user having to know
		450	anything about events.
		451
		452	3a. Event-based in a main program, using any support Event module:
		453
		454	use Event;
		455
		456	$fcp->txn_client_get ($url)->cb (sub {
		457	my $txn = shift;
		458	my $data = $txn->result;
		459	...
		460	});
		461
		462	Event::loop;
		463
		464	3b. The module user could use AnyEvent, too:
		465
		466	use AnyEvent;
		467
		468	my $quit = AnyEvent->condvar;
		469
		470	$fcp->txn_client_get ($url)->cb (sub {
		471	...
		472	$quit->broadcast;
		473	});
		474
		475	$quit->wait;
		476
140	=head1 SEE ALSO	477	=head1 SEE ALSO
141		478
142	L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>,	479	Event modules: L<Coro::Event>, L<Coro>, L<Event>, L<Glib::Event>, L<Glib>.
143	L<AnyEvent::Impl::Coro>,	480
144	L<AnyEvent::Impl::Event>,	481	Implementations: L<AnyEvent::Impl::Coro>, L<AnyEvent::Impl::Event>, L<AnyEvent::Impl::Glib>, L<AnyEvent::Impl::Tk>.
145	L<AnyEvent::Impl::Glib>,	482
146	L<AnyEvent::Impl::Tk>.	483	Nontrivial usage example: L<Net::FCP>.
147		484
148	=head1	485	=head1
149		486
150	=cut	487	=cut
151		488

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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 1.17 by root, Fri Nov 24 14:40:13 2006 UTC

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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 1.17 by root, Fri Nov 24 14:40:13 2006 UTC