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

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Revision 1.34 by root, Wed Aug 5 23:50:46 2009 UTC