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

Comparing cvsroot/AnyEvent-MP/MP.pm (file contents):
Revision 1.1 by root, Thu Jul 30 08:38:50 2009 UTC vs.
Revision 1.33 by root, Wed Aug 5 22:40:51 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 its 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 $NODE *SELF node_of _any_
		108	resolve_node initialise_node
		109	snd rcv mon kil reg psub
		110	port
		111	);
20		112
21	sub nonce($) {	113	our $SELF;
22	my $nonce;
23		114
24	if (open my $fh, "</dev/urandom") {	115	sub _self_die() {
25	sysread $fh, $nonce, $_[0];	116	my $msg = $@;
		117	$msg =~ s/\n+$// unless ref $msg;
		118	kil $SELF, die => $msg;
		119	}
		120
		121	=item $thisnode = NODE / $NODE
		122
		123	The C<NODE> function returns, and the C<$NODE> variable contains
		124	the noderef of the local node. The value is initialised by a call
		125	to C<become_public> or C<become_slave>, after which all local port
		126	identifiers become invalid.
		127
		128	=item $noderef = node_of $port
		129
		130	Extracts and returns the noderef from a portid or a noderef.
		131
		132	=item $cv = resolve_node $noderef
		133
		134	Takes an unresolved node reference that may contain hostnames and
		135	abbreviated IDs, resolves all of them and returns a resolved node
		136	reference.
		137
		138	In addition to C<address:port> pairs allowed in resolved noderefs, the
		139	following forms are supported:
		140
		141	=over 4
		142
		143	=item the empty string
		144
		145	An empty-string component gets resolved as if the default port (4040) was
		146	specified.
		147
		148	=item naked port numbers (e.g. C<1234>)
		149
		150	These are resolved by prepending the local nodename and a colon, to be
		151	further resolved.
		152
		153	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		154
		155	These are resolved by using AnyEvent::DNS to resolve them, optionally
		156	looking up SRV records for the C<aemp=4040> port, if no port was
		157	specified.
		158
		159	=back
		160
		161	=item $SELF
		162
		163	Contains the current port id while executing C<rcv> callbacks or C<psub>
		164	blocks.
		165
		166	=item SELF, %SELF, @SELF...
		167
		168	Due to some quirks in how perl exports variables, it is impossible to
		169	just export C<$SELF>, all the symbols called C<SELF> are exported by this
		170	module, but only C<$SELF> is currently used.
		171
		172	=item snd $port, type => @data
		173
		174	=item snd $port, @msg
		175
		176	Send the given message to the given port ID, which can identify either
		177	a local or a remote port, and can be either a string or soemthignt hat
		178	stringifies a sa port ID (such as a port object :).
		179
		180	While the message can be about anything, it is highly recommended to use a
		181	string as first element (a portid, or some word that indicates a request
		182	type etc.).
		183
		184	The message data effectively becomes read-only after a call to this
		185	function: modifying any argument is not allowed and can cause many
		186	problems.
		187
		188	The type of data you can transfer depends on the transport protocol: when
		189	JSON is used, then only strings, numbers and arrays and hashes consisting
		190	of those are allowed (no objects). When Storable is used, then anything
		191	that Storable can serialise and deserialise is allowed, and for the local
		192	node, anything can be passed.
		193
		194	=item $local_port = port
		195
		196	Create a new local port object that can be used either as a pattern
		197	matching port ("full port") or a single-callback port ("miniport"),
		198	depending on how C<rcv> callbacks are bound to the object.
		199
		200	=item $port = port { my @msg = @_; $finished }
		201
		202	Creates a "miniport", that is, a very lightweight port without any pattern
		203	matching behind it, and returns its ID. Semantically the same as creating
		204	a port and calling C<rcv $port, $callback> on it.
		205
		206	The block will be called for every message received on the port. When the
		207	callback returns a true value its job is considered "done" and the port
		208	will be destroyed. Otherwise it will stay alive.
		209
		210	The message will be passed as-is, no extra argument (i.e. no port id) will
		211	be passed to the callback.
		212
		213	If you need the local port id in the callback, this works nicely:
		214
		215	my $port; $port = port {
		216	snd $otherport, reply => $port;
		217	};
		218
		219	=cut
		220
		221	sub rcv($@);
		222
		223	sub port(;&) {
		224	my $id = "$UNIQ." . $ID++;
		225	my $port = "$NODE#$id";
		226
		227	if (@_) {
		228	rcv $port, shift;
26	} else {	229	} else {
27	# shit...	230	$PORT{$id} = sub { }; # nop
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	}	231	}
35		232
36	$nonce	233	$port
37	}	234	}
38		235
39	our $DEFAULT_SECRET;	236	=item reg $port, $name
40		237
41	sub default_secret {	238	Registers the given port under the name C<$name>. If the name already
42	unless (defined $DEFAULT_SECRET) {	239	exists it is replaced.
43	if (open my $fh, "<$ENV{HOME}/.aemp-secret") {	240
44	sysread $fh, $DEFAULT_SECRET, -s $fh;	241	A port can only be registered under one well known name.
		242
		243	A port automatically becomes unregistered when it is killed.
		244
		245	=cut
		246
		247	sub reg(@) {
		248	my ($port, $name) = @_;
		249
		250	$REG{$name} = $port;
		251	}
		252
		253	=item rcv $port, $callback->(@msg)
		254
		255	Replaces the callback on the specified miniport (after converting it to
		256	one if required).
		257
		258	=item rcv $port, tagstring => $callback->(@msg), ...
		259
		260	=item rcv $port, $smartmatch => $callback->(@msg), ...
		261
		262	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		263
		264	Register callbacks to be called on matching messages on the given full
		265	port (after converting it to one if required).
		266
		267	The callback has to return a true value when its work is done, after
		268	which is will be removed, or a false value in which case it will stay
		269	registered.
		270
		271	The global C<$SELF> (exported by this module) contains C<$port> while
		272	executing the callback.
		273
		274	Runtime errors wdurign callback execution will result in the port being
		275	C<kil>ed.
		276
		277	If the match is an array reference, then it will be matched against the
		278	first elements of the message, otherwise only the first element is being
		279	matched.
		280
		281	Any element in the match that is specified as C<_any_> (a function
		282	exported by this module) matches any single element of the message.
		283
		284	While not required, it is highly recommended that the first matching
		285	element is a string identifying the message. The one-string-only match is
		286	also the most efficient match (by far).
		287
		288	=cut
		289
		290	sub rcv($@) {
		291	my $port = shift;
		292	my ($noderef, $portid) = split /#/, $port, 2;
		293
		294	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		295	or Carp::croak "$port: rcv can only be called on local ports, caught";
		296
		297	if (@_ == 1) {
		298	my $cb = shift;
		299	delete $PORT_DATA{$portid};
		300	$PORT{$portid} = sub {
		301	local $SELF = $port;
		302	eval {
		303	&$cb
		304	and kil $port;
		305	};
		306	_self_die if $@;
		307	};
		308	} else {
		309	my $self = $PORT_DATA{$portid} \|\|= do {
		310	my $self = bless {
		311	id => $port,
		312	}, "AnyEvent::MP::Port";
		313
		314	$PORT{$portid} = sub {
		315	local $SELF = $port;
		316
		317	eval {
		318	for (@{ $self->{rc0}{$_[0]} }) {
		319	$_ && &{$_->[0]}
		320	&& undef $_;
		321	}
		322
		323	for (@{ $self->{rcv}{$_[0]} }) {
		324	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
		325	&& &{$_->[0]}
		326	&& undef $_;
		327	}
		328
		329	for (@{ $self->{any} }) {
		330	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
		331	&& &{$_->[0]}
		332	&& undef $_;
		333	}
		334	};
		335	_self_die if $@;
		336	};
		337
		338	$self
		339	};
		340
		341	"AnyEvent::MP::Port" eq ref $self
		342	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		343
		344	while (@_) {
		345	my ($match, $cb) = splice @_, 0, 2;
		346
		347	if (!ref $match) {
		348	push @{ $self->{rc0}{$match} }, [$cb];
		349	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
		350	my ($type, @match) = @$match;
		351	@match
		352	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
		353	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
45	} else {	354	} else {
46	$DEFAULT_SECRET = nonce 32;	355	push @{ $self->{any} }, [$cb, $match];
		356	}
47	}	357	}
48	}	358	}
49		359
50	$DEFAULT_SECRET	360	$port
51	}	361	}
		362
		363	=item $closure = psub { BLOCK }
		364
		365	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		366	closure is executed, sets up the environment in the same way as in C<rcv>
		367	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		368
		369	This is useful when you register callbacks from C<rcv> callbacks:
		370
		371	rcv delayed_reply => sub {
		372	my ($delay, @reply) = @_;
		373	my $timer = AE::timer $delay, 0, psub {
		374	snd @reply, $SELF;
		375	};
		376	};
		377
		378	=cut
		379
		380	sub psub(&) {
		381	my $cb = shift;
		382
		383	my $port = $SELF
		384	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		385
		386	sub {
		387	local $SELF = $port;
		388
		389	if (wantarray) {
		390	my @res = eval { &$cb };
		391	_self_die if $@;
		392	@res
		393	} else {
		394	my $res = eval { &$cb };
		395	_self_die if $@;
		396	$res
		397	}
		398	}
		399	}
		400
		401	=item $guard = mon $port, $cb->(@reason)
		402
		403	=item $guard = mon $port, $otherport
		404
		405	=item $guard = mon $port, $otherport, @msg
		406
		407	Monitor the given port and do something when the port is killed.
		408
		409	In the first form, the callback is simply called with any number
		410	of C<@reason> elements (no @reason means that the port was deleted
		411	"normally"). Note also that I<< the callback B<must> never die >>, so use
		412	C<eval> if unsure.
		413
		414	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
		415	a @reason was specified, i.e. on "normal" kils nothing happens, while
		416	under all other conditions, the other port is killed with the same reason.
		417
		418	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
		419
		420	Example: call a given callback when C<$port> is killed.
		421
		422	mon $port, sub { warn "port died because of <@_>\n" };
		423
		424	Example: kill ourselves when C<$port> is killed abnormally.
		425
		426	mon $port, $self;
		427
		428	Example: send us a restart message another C<$port> is killed.
		429
		430	mon $port, $self => "restart";
		431
		432	=cut
		433
		434	sub mon {
		435	my ($noderef, $port) = split /#/, shift, 2;
		436
		437	my $node = $NODE{$noderef} \|\| add_node $noderef;
		438
		439	my $cb = shift;
		440
		441	unless (ref $cb) {
		442	if (@_) {
		443	# send a kill info message
		444	my (@msg) = ($cb, @_);
		445	$cb = sub { snd @msg, @_ };
		446	} else {
		447	# simply kill other port
		448	my $port = $cb;
		449	$cb = sub { kil $port, @_ if @_ };
		450	}
		451	}
		452
		453	$node->monitor ($port, $cb);
		454
		455	defined wantarray
		456	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		457	}
		458
		459	=item $guard = mon_guard $port, $ref, $ref...
		460
		461	Monitors the given C<$port> and keeps the passed references. When the port
		462	is killed, the references will be freed.
		463
		464	Optionally returns a guard that will stop the monitoring.
		465
		466	This function is useful when you create e.g. timers or other watchers and
		467	want to free them when the port gets killed:
		468
		469	$port->rcv (start => sub {
		470	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		471	undef $timer if 0.9 < rand;
		472	});
		473	});
		474
		475	=cut
		476
		477	sub mon_guard {
		478	my ($port, @refs) = @_;
		479
		480	mon $port, sub { 0 && @refs }
		481	}
		482
		483	=item lnk $port1, $port2
		484
		485	Link two ports. This is simply a shorthand for:
		486
		487	mon $port1, $port2;
		488	mon $port2, $port1;
		489
		490	It means that if either one is killed abnormally, the other one gets
		491	killed as well.
		492
		493	=item kil $port[, @reason]
		494
		495	Kill the specified port with the given C<@reason>.
		496
		497	If no C<@reason> is specified, then the port is killed "normally" (linked
		498	ports will not be kileld, or even notified).
		499
		500	Otherwise, linked ports get killed with the same reason (second form of
		501	C<mon>, see below).
		502
		503	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		504	will be reported as reason C<< die => $@ >>.
		505
		506	Transport/communication errors are reported as C<< transport_error =>
		507	$message >>.
		508
		509	=back
		510
		511	=head1 FUNCTIONS FOR NODES
		512
		513	=over 4
		514
		515	=item initialise_node $noderef, $seednode, $seednode...
		516
		517	=item initialise_node "slave/", $master, $master...
		518
		519	Initialises a node - must be called exactly once before calling other
		520	AnyEvent::MP functions when talking to other nodes is required.
		521
		522	All arguments are noderefs, which can be either resolved or unresolved.
		523
		524	There are two types of networked nodes, public nodes and slave nodes:
		525
		526	=over 4
		527
		528	=item public nodes
		529
		530	For public nodes, C<$noderef> must either be a (possibly unresolved)
		531	noderef, in which case it will be resolved, or C<undef> (or missing), in
		532	which case the noderef will be guessed.
		533
		534	Afterwards, the node will bind itself on all endpoints and try to connect
		535	to all additional C<$seednodes> that are specified. Seednodes are optional
		536	and can be used to quickly bootstrap the node into an existing network.
		537
		538	=item slave nodes
		539
		540	When the C<$noderef> is the special string C<slave/>, then the node will
		541	become a slave node. Slave nodes cannot be contacted from outside and will
		542	route most of their traffic to the master node that they attach to.
		543
		544	At least one additional noderef is required: The node will try to connect
		545	to all of them and will become a slave attached to the first node it can
		546	successfully connect to.
		547
		548	=back
		549
		550	This function will block until all nodes have been resolved and, for slave
		551	nodes, until it has successfully established a connection to a master
		552	server.
		553
		554	Example: become a public node listening on the default node.
		555
		556	initialise_node;
		557
		558	Example: become a public node, and try to contact some well-known master
		559	servers to become part of the network.
		560
		561	initialise_node undef, "master1", "master2";
		562
		563	Example: become a public node listening on port C<4041>.
		564
		565	initialise_node 4041;
		566
		567	Example: become a public node, only visible on localhost port 4044.
		568
		569	initialise_node "locahost:4044";
		570
		571	Example: become a slave node to any of the specified master servers.
		572
		573	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		574
		575	=cut
		576
		577	=back
		578
		579	=head1 NODE MESSAGES
		580
		581	Nodes understand the following messages sent to them. Many of them take
		582	arguments called C<@reply>, which will simply be used to compose a reply
		583	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
		584	the remaining arguments are simply the message data.
		585
		586	While other messages exist, they are not public and subject to change.
		587
		588	=over 4
		589
		590	=cut
		591
		592	=item lookup => $name, @reply
		593
		594	Replies with the port ID of the specified well-known port, or C<undef>.
		595
		596	=item devnull => ...
		597
		598	Generic data sink/CPU heat conversion.
		599
		600	=item relay => $port, @msg
		601
		602	Simply forwards the message to the given port.
		603
		604	=item eval => $string[ @reply]
		605
		606	Evaluates the given string. If C<@reply> is given, then a message of the
		607	form C<@reply, $@, @evalres> is sent.
		608
		609	Example: crash another node.
		610
		611	snd $othernode, eval => "exit";
		612
		613	=item time => @reply
		614
		615	Replies the the current node time to C<@reply>.
		616
		617	Example: tell the current node to send the current time to C<$myport> in a
		618	C<timereply> message.
		619
		620	snd $NODE, time => $myport, timereply => 1, 2;
		621	# => snd $myport, timereply => 1, 2, <time>
		622
		623	=back
		624
		625	=head1 AnyEvent::MP vs. Distributed Erlang
		626
		627	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node
		628	== aemp node, erlang process == aemp port), so many of the documents and
		629	programming techniques employed by erlang apply to AnyEvent::MP. Here is a
		630	sample:
		631
		632	http://www.erlang.se/doc/programming_rules.shtml
		633	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		634	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
		635	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		636
		637	Despite the similarities, there are also some important differences:
		638
		639	=over 4
		640
		641	=item * Node references contain the recipe on how to contact them.
		642
		643	Erlang relies on special naming and DNS to work everywhere in the
		644	same way. AEMP relies on each node knowing it's own address(es), with
		645	convenience functionality.
		646
		647	This means that AEMP requires a less tightly controlled environment at the
		648	cost of longer node references and a slightly higher management overhead.
		649
		650	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		651
		652	Erlang uses processes that selctively receive messages, and therefore
		653	needs a queue. AEMP is event based, queuing messages would serve no useful
		654	purpose.
		655
		656	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).
		657
		658	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		659
		660	Sending messages in erlang is synchronous and blocks the process. AEMP
		661	sends are immediate, connection establishment is handled in the
		662	background.
		663
		664	=item * Erlang can silently lose messages, AEMP cannot.
		665
		666	Erlang makes few guarantees on messages delivery - messages can get lost
		667	without any of the processes realising it (i.e. you send messages a, b,
		668	and c, and the other side only receives messages a and c).
		669
		670	AEMP guarantees correct ordering, and the guarantee that there are no
		671	holes in the message sequence.
		672
		673	=item * In erlang, processes can be declared dead and later be found to be
		674	alive.
		675
		676	In erlang it can happen that a monitored process is declared dead and
		677	linked processes get killed, but later it turns out that the process is
		678	still alive - and can receive messages.
		679
		680	In AEMP, when port monitoring detects a port as dead, then that port will
		681	eventually be killed - it cannot happen that a node detects a port as dead
		682	and then later sends messages to it, finding it is still alive.
		683
		684	=item * Erlang can send messages to the wrong port, AEMP does not.
		685
		686	In erlang it is quite possible that a node that restarts reuses a process
		687	ID known to other nodes for a completely different process, causing
		688	messages destined for that process to end up in an unrelated process.
		689
		690	AEMP never reuses port IDs, so old messages or old port IDs floating
		691	around in the network will not be sent to an unrelated port.
		692
		693	=item * Erlang uses unprotected connections, AEMP uses secure
		694	authentication and can use TLS.
		695
		696	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		697	securely authenticate nodes.
		698
		699	=item * The AEMP protocol is optimised for both text-based and binary
		700	communications.
		701
		702	The AEMP protocol, unlike the erlang protocol, supports both
		703	language-independent text-only protocols (good for debugging) and binary,
		704	language-specific serialisers (e.g. Storable).
		705
		706	It has also been carefully designed to be implementable in other languages
		707	with a minimum of work while gracefully degrading fucntionality to make the
		708	protocol simple.
		709
		710	=back
52		711
53	=head1 SEE ALSO	712	=head1 SEE ALSO
54		713
55	L<AnyEvent>.	714	L<AnyEvent>.
56		715

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Revision 1.33 by root, Wed Aug 5 22:40:51 2009 UTC