[ViewVC] Diff of: cvs/AnyEvent-MP/MP.pm

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.1 by root, Thu Jul 30 08:38:50 2009 UTC vs.
Revision 1.29 by root, Tue Aug 4 23:16:57 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
		9	$NODE # contains this node's noderef
		10	NODE # returns this node's noderef
		11	NODE $port # returns the noderef of the port
		12
		13	snd $port, type => data...;
		14
		15	$SELF # receiving/own port id in rcv callbacks
		16
		17	rcv $port, smartmatch => $cb->($port, @msg);
		18
		19	# examples:
		20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };
		21	rcv $port1, pong => sub { warn "pong received\n" };
		22	snd $port2, ping => $port1;
		23
		24	# more, smarter, matches (_any_ is exported by this module)
		25	rcv $port, [child_died => $pid] => sub { ...
		26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
		27
9	=head1 DESCRIPTION	28	=head1 DESCRIPTION
10		29
		30	This module (-family) implements a simple message passing framework.
		31
		32	Despite its simplicity, you can securely message other processes running
		33	on the same or other hosts.
		34
		35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		36	manual page.
		37
		38	At the moment, this module family is severly broken and underdocumented,
		39	so do not use. This was uploaded mainly to reserve the CPAN namespace -
		40	stay tuned! The basic API should be finished, however.
		41
		42	=head1 CONCEPTS
		43
		44	=over 4
		45
		46	=item port
		47
		48	A port is something you can send messages to (with the C<snd> function).
		49
		50	Some ports allow you to register C<rcv> handlers that can match specific
		51	messages. All C<rcv> handlers will receive messages they match, messages
		52	will not be queued.
		53
		54	=item port id - C<noderef#portname>
		55
		56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as
		57	separator, and a port name (a printable string of unspecified format). An
		58	exception is the the node port, whose ID is identical to it's node
		59	reference.
		60
		61	=item node
		62
		63	A node is a single process containing at least one port - the node
		64	port. You can send messages to node ports to find existing ports or to
		65	create new ports, among other things.
		66
		67	Nodes are either private (single-process only), slaves (connected to a
		68	master node only) or public nodes (connectable from unrelated nodes).
		69
		70	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
		71
		72	A node reference is a string that either simply identifies the node (for
		73	private and slave nodes), or contains a recipe on how to reach a given
		74	node (for public nodes).
		75
		76	This recipe is simply a comma-separated list of C<address:port> pairs (for
		77	TCP/IP, other protocols might look different).
		78
		79	Node references come in two flavours: resolved (containing only numerical
		80	addresses) or unresolved (where hostnames are used instead of addresses).
		81
		82	Before using an unresolved node reference in a message you first have to
		83	resolve it.
		84
		85	=back
		86
		87	=head1 VARIABLES/FUNCTIONS
		88
		89	=over 4
		90
11	=cut	91	=cut
12		92
13	package AnyEvent::MP;	93	package AnyEvent::MP;
14		94
		95	use AnyEvent::MP::Base;
		96
15	use common::sense;	97	use common::sense;
16		98
		99	use Carp ();
		100
17	use AE ();	101	use AE ();
18		102
		103	use base "Exporter";
		104
19	our $VERSION = '0.0';	105	our $VERSION = '0.1';
		106	our @EXPORT = qw(
		107	NODE $NODE *SELF node_of _any_
		108	resolve_node
		109	become_slave become_public
		110	snd rcv mon kil reg psub
		111	port
		112	);
20		113
21	sub nonce($) {	114	our $SELF;
22	my $nonce;
23		115
24	if (open my $fh, "</dev/urandom") {	116	sub _self_die() {
25	sysread $fh, $nonce, $_[0];	117	my $msg = $@;
26	} else {	118	$msg =~ s/\n+$// unless ref $msg;
27	# shit...	119	kil $SELF, die => $msg;
28	our $nonce_init;
29	unless ($nonce_init++) {
30	srand time ^ $$ ^ unpack "%L*", qx"ps -edalf" . qx"ipconfig /all";
31	}
32
33	$nonce = join "", map +(chr rand 256), 1 .. $_[0]
34	}
35
36	$nonce
37	}	120	}
38		121
39	our $DEFAULT_SECRET;	122	=item $thisnode = NODE / $NODE
40		123
41	sub default_secret {	124	The C<NODE> function returns, and the C<$NODE> variable contains
42	unless (defined $DEFAULT_SECRET) {	125	the noderef of the local node. The value is initialised by a call
43	if (open my $fh, "<$ENV{HOME}/.aemp-secret") {	126	to C<become_public> or C<become_slave>, after which all local port
44	sysread $fh, $DEFAULT_SECRET, -s $fh;	127	identifiers become invalid.
		128
		129	=item $noderef = node_of $portid
		130
		131	Extracts and returns the noderef from a portid or a noderef.
		132
		133	=item $cv = resolve_node $noderef
		134
		135	Takes an unresolved node reference that may contain hostnames and
		136	abbreviated IDs, resolves all of them and returns a resolved node
		137	reference.
		138
		139	In addition to C<address:port> pairs allowed in resolved noderefs, the
		140	following forms are supported:
		141
		142	=over 4
		143
		144	=item the empty string
		145
		146	An empty-string component gets resolved as if the default port (4040) was
		147	specified.
		148
		149	=item naked port numbers (e.g. C<1234>)
		150
		151	These are resolved by prepending the local nodename and a colon, to be
		152	further resolved.
		153
		154	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		155
		156	These are resolved by using AnyEvent::DNS to resolve them, optionally
		157	looking up SRV records for the C<aemp=4040> port, if no port was
		158	specified.
		159
		160	=back
		161
		162	=item $SELF
		163
		164	Contains the current port id while executing C<rcv> callbacks or C<psub>
		165	blocks.
		166
		167	=item SELF, %SELF, @SELF...
		168
		169	Due to some quirks in how perl exports variables, it is impossible to
		170	just export C<$SELF>, all the symbols called C<SELF> are exported by this
		171	module, but only C<$SELF> is currently used.
		172
		173	=item snd $portid, type => @data
		174
		175	=item snd $portid, @msg
		176
		177	Send the given message to the given port ID, which can identify either
		178	a local or a remote port, and can be either a string or soemthignt hat
		179	stringifies a sa port ID (such as a port object :).
		180
		181	While the message can be about anything, it is highly recommended to use a
		182	string as first element (a portid, or some word that indicates a request
		183	type etc.).
		184
		185	The message data effectively becomes read-only after a call to this
		186	function: modifying any argument is not allowed and can cause many
		187	problems.
		188
		189	The type of data you can transfer depends on the transport protocol: when
		190	JSON is used, then only strings, numbers and arrays and hashes consisting
		191	of those are allowed (no objects). When Storable is used, then anything
		192	that Storable can serialise and deserialise is allowed, and for the local
		193	node, anything can be passed.
		194
		195	=item kil $portid[, @reason]
		196
		197	Kill the specified port with the given C<@reason>.
		198
		199	If no C<@reason> is specified, then the port is killed "normally" (linked
		200	ports will not be kileld, or even notified).
		201
		202	Otherwise, linked ports get killed with the same reason (second form of
		203	C<mon>, see below).
		204
		205	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		206	will be reported as reason C<< die => $@ >>.
		207
		208	Transport/communication errors are reported as C<< transport_error =>
		209	$message >>.
		210
		211	=item $guard = mon $portid, $cb->(@reason)
		212
		213	=item $guard = mon $portid, $otherport
		214
		215	=item $guard = mon $portid, $otherport, @msg
		216
		217	Monitor the given port and do something when the port is killed.
		218
		219	In the first form, the callback is simply called with any number
		220	of C<@reason> elements (no @reason means that the port was deleted
		221	"normally"). Note also that I<< the callback B<must> never die >>, so use
		222	C<eval> if unsure.
		223
		224	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
		225	a @reason was specified, i.e. on "normal" kils nothing happens, while
		226	under all other conditions, the other port is killed with the same reason.
		227
		228	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
		229
		230	Example: call a given callback when C<$port> is killed.
		231
		232	mon $port, sub { warn "port died because of <@_>\n" };
		233
		234	Example: kill ourselves when C<$port> is killed abnormally.
		235
		236	mon $port, $self;
		237
		238	Example: send us a restart message another C<$port> is killed.
		239
		240	mon $port, $self => "restart";
		241
		242	=cut
		243
		244	sub mon {
		245	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);
		246
		247	my $node = $NODE{$noderef} \|\| add_node $noderef;
		248
		249	#TODO: ports must not be references
		250	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {
		251	if (@_) {
		252	# send a kill info message
		253	my (@msg) = ($cb, @_);
		254	$cb = sub { snd @msg, @_ };
45	} else {	255	} else {
46	$DEFAULT_SECRET = nonce 32;	256	# simply kill other port
		257	my $port = $cb;
		258	$cb = sub { kil $port, @_ if @_ };
47	}	259	}
48	}	260	}
49		261
50	$DEFAULT_SECRET	262	$node->monitor ($port, $cb);
		263
		264	defined wantarray
		265	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
51	}	266	}
		267
		268	=item $guard = mon_guard $port, $ref, $ref...
		269
		270	Monitors the given C<$port> and keeps the passed references. When the port
		271	is killed, the references will be freed.
		272
		273	Optionally returns a guard that will stop the monitoring.
		274
		275	This function is useful when you create e.g. timers or other watchers and
		276	want to free them when the port gets killed:
		277
		278	$port->rcv (start => sub {
		279	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		280	undef $timer if 0.9 < rand;
		281	});
		282	});
		283
		284	=cut
		285
		286	sub mon_guard {
		287	my ($port, @refs) = @_;
		288
		289	mon $port, sub { 0 && @refs }
		290	}
		291
		292	=item lnk $port1, $port2
		293
		294	Link two ports. This is simply a shorthand for:
		295
		296	mon $port1, $port2;
		297	mon $port2, $port1;
		298
		299	It means that if either one is killed abnormally, the other one gets
		300	killed as well.
		301
		302	=item $local_port = port
		303
		304	Create a new local port object that supports message matching.
		305
		306	=item $portid = port { my @msg = @_; $finished }
		307
		308	Creates a "mini port", that is, a very lightweight port without any
		309	pattern matching behind it, and returns its ID.
		310
		311	The block will be called for every message received on the port. When the
		312	callback returns a true value its job is considered "done" and the port
		313	will be destroyed. Otherwise it will stay alive.
		314
		315	The message will be passed as-is, no extra argument (i.e. no port id) will
		316	be passed to the callback.
		317
		318	If you need the local port id in the callback, this works nicely:
		319
		320	my $port; $port = miniport {
		321	snd $otherport, reply => $port;
		322	};
		323
		324	=cut
		325
		326	sub port(;&) {
		327	my $id = "$UNIQ." . $ID++;
		328	my $port = "$NODE#$id";
		329
		330	if (@_) {
		331	my $cb = shift;
		332	$PORT{$id} = sub {
		333	local $SELF = $port;
		334	eval {
		335	&$cb
		336	and kil $id;
		337	};
		338	_self_die if $@;
		339	};
		340	} else {
		341	my $self = bless {
		342	id => "$NODE#$id",
		343	}, "AnyEvent::MP::Port";
		344
		345	$PORT_DATA{$id} = $self;
		346	$PORT{$id} = sub {
		347	local $SELF = $port;
		348
		349	eval {
		350	for (@{ $self->{rc0}{$_[0]} }) {
		351	$_ && &{$_->[0]}
		352	&& undef $_;
		353	}
		354
		355	for (@{ $self->{rcv}{$_[0]} }) {
		356	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
		357	&& &{$_->[0]}
		358	&& undef $_;
		359	}
		360
		361	for (@{ $self->{any} }) {
		362	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
		363	&& &{$_->[0]}
		364	&& undef $_;
		365	}
		366	};
		367	_self_die if $@;
		368	};
		369	}
		370
		371	$port
		372	}
		373
		374	=item reg $portid, $name
		375
		376	Registers the given port under the name C<$name>. If the name already
		377	exists it is replaced.
		378
		379	A port can only be registered under one well known name.
		380
		381	A port automatically becomes unregistered when it is killed.
		382
		383	=cut
		384
		385	sub reg(@) {
		386	my ($portid, $name) = @_;
		387
		388	$REG{$name} = $portid;
		389	}
		390
		391	=item rcv $portid, tagstring => $callback->(@msg), ...
		392
		393	=item rcv $portid, $smartmatch => $callback->(@msg), ...
		394
		395	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
		396
		397	Register callbacks to be called on matching messages on the given port.
		398
		399	The callback has to return a true value when its work is done, after
		400	which is will be removed, or a false value in which case it will stay
		401	registered.
		402
		403	The global C<$SELF> (exported by this module) contains C<$portid> while
		404	executing the callback.
		405
		406	Runtime errors wdurign callback execution will result in the port being
		407	C<kil>ed.
		408
		409	If the match is an array reference, then it will be matched against the
		410	first elements of the message, otherwise only the first element is being
		411	matched.
		412
		413	Any element in the match that is specified as C<_any_> (a function
		414	exported by this module) matches any single element of the message.
		415
		416	While not required, it is highly recommended that the first matching
		417	element is a string identifying the message. The one-string-only match is
		418	also the most efficient match (by far).
		419
		420	=cut
		421
		422	sub rcv($@) {
		423	my ($noderef, $port) = split /#/, shift, 2;
		424
		425	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		426	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
		427
		428	my $self = $PORT_DATA{$port}
		429	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
		430
		431	"AnyEvent::MP::Port" eq ref $self
		432	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
		433
		434	while (@_) {
		435	my ($match, $cb) = splice @_, 0, 2;
		436
		437	if (!ref $match) {
		438	push @{ $self->{rc0}{$match} }, [$cb];
		439	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
		440	my ($type, @match) = @$match;
		441	@match
		442	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
		443	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
		444	} else {
		445	push @{ $self->{any} }, [$cb, $match];
		446	}
		447	}
		448	}
		449
		450	=item $closure = psub { BLOCK }
		451
		452	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		453	closure is executed, sets up the environment in the same way as in C<rcv>
		454	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		455
		456	This is useful when you register callbacks from C<rcv> callbacks:
		457
		458	rcv delayed_reply => sub {
		459	my ($delay, @reply) = @_;
		460	my $timer = AE::timer $delay, 0, psub {
		461	snd @reply, $SELF;
		462	};
		463	};
		464
		465	=cut
		466
		467	sub psub(&) {
		468	my $cb = shift;
		469
		470	my $port = $SELF
		471	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		472
		473	sub {
		474	local $SELF = $port;
		475
		476	if (wantarray) {
		477	my @res = eval { &$cb };
		478	_self_die if $@;
		479	@res
		480	} else {
		481	my $res = eval { &$cb };
		482	_self_die if $@;
		483	$res
		484	}
		485	}
		486	}
		487
		488	=back
		489
		490	=head1 FUNCTIONS FOR NODES
		491
		492	=over 4
		493
		494	=item become_public $noderef
		495
		496	Tells the node to become a public node, i.e. reachable from other nodes.
		497
		498	The first argument is the (unresolved) node reference of the local node
		499	(if missing then the empty string is used).
		500
		501	It is quite common to not specify anything, in which case the local node
		502	tries to listen on the default port, or to only specify a port number, in
		503	which case AnyEvent::MP tries to guess the local addresses.
		504
		505	=cut
		506
		507	=back
		508
		509	=head1 NODE MESSAGES
		510
		511	Nodes understand the following messages sent to them. Many of them take
		512	arguments called C<@reply>, which will simply be used to compose a reply
		513	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
		514	the remaining arguments are simply the message data.
		515
		516	While other messages exist, they are not public and subject to change.
		517
		518	=over 4
		519
		520	=cut
		521
		522	=item lookup => $name, @reply
		523
		524	Replies with the port ID of the specified well-known port, or C<undef>.
		525
		526	=item devnull => ...
		527
		528	Generic data sink/CPU heat conversion.
		529
		530	=item relay => $port, @msg
		531
		532	Simply forwards the message to the given port.
		533
		534	=item eval => $string[ @reply]
		535
		536	Evaluates the given string. If C<@reply> is given, then a message of the
		537	form C<@reply, $@, @evalres> is sent.
		538
		539	Example: crash another node.
		540
		541	snd $othernode, eval => "exit";
		542
		543	=item time => @reply
		544
		545	Replies the the current node time to C<@reply>.
		546
		547	Example: tell the current node to send the current time to C<$myport> in a
		548	C<timereply> message.
		549
		550	snd $NODE, time => $myport, timereply => 1, 2;
		551	# => snd $myport, timereply => 1, 2, <time>
		552
		553	=back
		554
		555	=head1 AnyEvent::MP vs. Distributed Erlang
		556
		557	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
		558	== aemp node, erlang process == aemp port), so many of the documents and
		559	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
		560	sample:
		561
		562	http://www.erlang.se/doc/programming_rules.shtml
		563	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		564	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
		565	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		566
		567	Despite the similarities, there are also some important differences:
		568
		569	=over 4
		570
		571	=item * Node references contain the recipe on how to contact them.
		572
		573	Erlang relies on special naming and DNS to work everywhere in the
		574	same way. AEMP relies on each node knowing it's own address(es), with
		575	convenience functionality.
		576
		577	This means that AEMP requires a less tightly controlled environment at the
		578	cost of longer node references and a slightly higher management overhead.
		579
		580	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		581
		582	Erlang uses processes that selctively receive messages, and therefore
		583	needs a queue. AEMP is event based, queuing messages would serve no useful
		584	purpose.
		585
		586	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).
		587
		588	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		589
		590	Sending messages in erlang is synchronous and blocks the process. AEMP
		591	sends are immediate, connection establishment is handled in the
		592	background.
		593
		594	=item * Erlang can silently lose messages, AEMP cannot.
		595
		596	Erlang makes few guarantees on messages delivery - messages can get lost
		597	without any of the processes realising it (i.e. you send messages a, b,
		598	and c, and the other side only receives messages a and c).
		599
		600	AEMP guarantees correct ordering, and the guarantee that there are no
		601	holes in the message sequence.
		602
		603	=item * In erlang, processes can be declared dead and later be found to be
		604	alive.
		605
		606	In erlang it can happen that a monitored process is declared dead and
		607	linked processes get killed, but later it turns out that the process is
		608	still alive - and can receive messages.
		609
		610	In AEMP, when port monitoring detects a port as dead, then that port will
		611	eventually be killed - it cannot happen that a node detects a port as dead
		612	and then later sends messages to it, finding it is still alive.
		613
		614	=item * Erlang can send messages to the wrong port, AEMP does not.
		615
		616	In erlang it is quite possible that a node that restarts reuses a process
		617	ID known to other nodes for a completely different process, causing
		618	messages destined for that process to end up in an unrelated process.
		619
		620	AEMP never reuses port IDs, so old messages or old port IDs floating
		621	around in the network will not be sent to an unrelated port.
		622
		623	=item * Erlang uses unprotected connections, AEMP uses secure
		624	authentication and can use TLS.
		625
		626	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		627	securely authenticate nodes.
		628
		629	=item * The AEMP protocol is optimised for both text-based and binary
		630	communications.
		631
		632	The AEMP protocol, unlike the erlang protocol, supports both
		633	language-independent text-only protocols (good for debugging) and binary,
		634	language-specific serialisers (e.g. Storable).
		635
		636	It has also been carefully designed to be implementable in other languages
		637	with a minimum of work while gracefully degrading fucntionality to make the
		638	protocol simple.
		639
		640	=back
52		641
53	=head1 SEE ALSO	642	=head1 SEE ALSO
54		643
55	L<AnyEvent>.	644	L<AnyEvent>.
56		645

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.1 by root, Thu Jul 30 08:38:50 2009 UTC vs. Revision 1.29 by root, Tue Aug 4 23:16:57 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.1 by root, Thu Jul 30 08:38:50 2009 UTC vs.
Revision 1.29 by root, Tue Aug 4 23:16:57 2009 UTC