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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.7 by root, Sat Aug 1 15:04:30 2009 UTC vs.
Revision 1.46 by root, Thu Aug 13 01:46:10 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	NODE # returns this node identifier
10	$NODE # contains this node identifier	9	$NODE # contains this node's noderef
		10	NODE # returns this node's noderef
		11	NODE $port # returns the noderef of the port
11		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# ports are message endpoints
		16
		17	# sending messages
12	snd $port, type => data...;	18	snd $port, type => data...;
		19	snd $port, @msg;
		20	snd @msg_with_first_element_being_a_port;
13		21
		22	# miniports
		23	my $miniport = port { my @msg = @_; 0 };
		24
		25	# full ports
		26	my $port = port;
14	rcv $port, smartmatch => $cb->($port, @msg);	27	rcv $port, smartmatch => $cb->(@msg);
15
16	# examples:
17	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
18	rcv $port1, pong => sub { warn "pong received\n" };	29	rcv $port, pong => sub { warn "pong received\n"; 0 };
19	snd $port2, ping => $port1;	30
		31	# remote ports
		32	my $port = spawn $node, $initfunc, @initdata;
20		33
21	# more, smarter, matches (_any_ is exported by this module)	34	# more, smarter, matches (_any_ is exported by this module)
22	rcv $port, [child_died => $pid] => sub { ...	35	rcv $port, [child_died => $pid] => sub { ...
23	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
24		37
		38	# monitoring
		39	mon $port, $cb->(@msg) # callback is invoked on death
		40	mon $port, $otherport # kill otherport on abnormal death
		41	mon $port, $otherport, @msg # send message on death
		42
		43	=head1 CURRENT STATUS
		44
		45	AnyEvent::MP - stable API, should work
		46	AnyEvent::MP::Intro - outdated
		47	AnyEvent::MP::Kernel - WIP
		48	AnyEvent::MP::Transport - mostly stable
		49
		50	stay tuned.
		51
25	=head1 DESCRIPTION	52	=head1 DESCRIPTION
26		53
27	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
28		55
29	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
30	on the same or other hosts.	57	on the same or other hosts.
31		58
		59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		60	manual page.
		61
32	At the moment, this module family is severly brokena nd underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
33	so do not use. This was uploaded mainly to resreve the CPAN namespace -	63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
34	stay tuned!	64	stay tuned!
35		65
36	=head1 CONCEPTS	66	=head1 CONCEPTS
37		67
38	=over 4	68	=over 4
39		69
40	=item port	70	=item port
41		71
42	A port is something you can send messages to with the C<snd> function, and	72	A port is something you can send messages to (with the C<snd> function).
43	you can register C<rcv> handlers with. All C<rcv> handlers will receive	73
44	messages they match, messages will not be queued.	74	Some ports allow you to register C<rcv> handlers that can match specific
		75	messages. All C<rcv> handlers will receive messages they match, messages
		76	will not be queued.
45		77
46	=item port id - C<noderef#portname>	78	=item port id - C<noderef#portname>
47		79
48	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	80	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as
49	by a port name (a printable string of unspecified format).	81	separator, and a port name (a printable string of unspecified format). An
		82	exception is the the node port, whose ID is identical to its node
		83	reference.
50		84
51	=item node	85	=item node
52		86
53	A node is a single process containing at least one port - the node	87	A node is a single process containing at least one port - the node
54	port. You can send messages to node ports to let them create new ports,	88	port. You can send messages to node ports to find existing ports or to
55	among other things.	89	create new ports, among other things.
56		90
57	Initially, nodes are either private (single-process only) or hidden	91	Nodes are either private (single-process only), slaves (connected to a
58	(connected to a master node only). Only when they epxlicitly "become	92	master node only) or public nodes (connectable from unrelated nodes).
59	public" can you send them messages from unrelated other nodes.
60		93
61	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	94	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
62		95
63	A noderef is a string that either uniquely identifies a given node (for	96	A node reference is a string that either simply identifies the node (for
64	private and hidden nodes), or contains a recipe on how to reach a given	97	private and slave nodes), or contains a recipe on how to reach a given
65	node (for public nodes).	98	node (for public nodes).
66		99
		100	This recipe is simply a comma-separated list of C<address:port> pairs (for
		101	TCP/IP, other protocols might look different).
		102
		103	Node references come in two flavours: resolved (containing only numerical
		104	addresses) or unresolved (where hostnames are used instead of addresses).
		105
		106	Before using an unresolved node reference in a message you first have to
		107	resolve it.
		108
67	=back	109	=back
68		110
69	=head1 VARIABLES/FUNCTIONS	111	=head1 VARIABLES/FUNCTIONS
70		112
71	=over 4	113	=over 4
72		114
73	=cut	115	=cut
74		116
75	package AnyEvent::MP;	117	package AnyEvent::MP;
76		118
77	use AnyEvent::MP::Util ();
78	use AnyEvent::MP::Node;	119	use AnyEvent::MP::Kernel;
79	use AnyEvent::MP::Transport;
80		120
81	use utf8;
82	use common::sense;	121	use common::sense;
83		122
84	use Carp ();	123	use Carp ();
85		124
86	use AE ();	125	use AE ();
87		126
88	use base "Exporter";	127	use base "Exporter";
89		128
90	our $VERSION = '0.01';	129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
91	our @EXPORT = qw(NODE $NODE $PORT snd rcv _any_);
92		130
93	our $DEFAULT_SECRET;	131	our @EXPORT = qw(
94	our $DEFAULT_PORT = "4040";	132	NODE $NODE *SELF node_of _any_
		133	resolve_node initialise_node
		134	snd rcv mon kil reg psub spawn
		135	port
		136	);
95		137
96	our $CONNECT_INTERVAL = 5; # new connect every 5s, at least	138	our $SELF;
97	our $CONNECT_TIMEOUT = 30; # includes handshake
98		139
99	sub default_secret {	140	sub _self_die() {
100	unless (defined $DEFAULT_SECRET) {	141	my $msg = $@;
101	if (open my $fh, "<$ENV{HOME}/.aemp-secret") {	142	$msg =~ s/\n+$// unless ref $msg;
102	sysread $fh, $DEFAULT_SECRET, -s $fh;	143	kil $SELF, die => $msg;
103	} else {
104	$DEFAULT_SECRET = AnyEvent::MP::Util::nonce 32;
105	}
106	}
107
108	$DEFAULT_SECRET
109	}	144	}
110		145
111	=item NODE / $NODE	146	=item $thisnode = NODE / $NODE
112		147
113	The C<NODE ()> function and the C<$NODE> variable contain the noderef of	148	The C<NODE> function returns, and the C<$NODE> variable contains
114	the local node. The value is initialised by a call to C<become_public> or	149	the noderef of the local node. The value is initialised by a call
115	C<become_slave>, after which all local port identifiers become invalid.	150	to C<become_public> or C<become_slave>, after which all local port
		151	identifiers become invalid.
116		152
117	=cut	153	=item $noderef = node_of $port
118		154
119	our $UNIQ = sprintf "%x.%x", $$, time; # per-process/node unique cookie	155	Extracts and returns the noderef from a portid or a noderef.
120	our $ID = "a0";
121	our $PUBLIC = 0;
122	our $NODE;
123	our $PORT;
124		156
125	our %NODE; # node id to transport mapping, or "undef", for local node	157	=item initialise_node $noderef, $seednode, $seednode...
126	our %PORT; # local ports
127	our %LISTENER; # local transports
128		158
129	sub NODE() { $NODE }	159	=item initialise_node "slave/", $master, $master...
130		160
131	{	161	Before a node can talk to other nodes on the network it has to initialise
132	use POSIX ();	162	itself - the minimum a node needs to know is it's own name, and optionally
133	my $nodename = (POSIX::uname)[1];	163	it should know the noderefs of some other nodes in the network.
134	$NODE = "$$\@$nodename";
135	}
136		164
137	sub _ANY_() { 1 }	165	This function initialises a node - it must be called exactly once (or
138	sub _any_() { \&_ANY_ }	166	never) before calling other AnyEvent::MP functions.
139		167
140	sub add_node {	168	All arguments are noderefs, which can be either resolved or unresolved.
141	my ($noderef) = @_;
142		169
143	return $NODE{$noderef}	170	There are two types of networked nodes, public nodes and slave nodes:
144	if exists $NODE{$noderef};
145		171
146	for (split /,/, $noderef) {	172	=over 4
147	return $NODE{$noderef} = $NODE{$_}
148	if exists $NODE{$_};
149	}
150		173
151	# for indirect sends, use a different class	174	=item public nodes
152	my $node = new AnyEvent::MP::Node::Direct $noderef;
153		175
154	$NODE{$_} = $node	176	For public nodes, C<$noderef> must either be a (possibly unresolved)
155	for $noderef, split /,/, $noderef;	177	noderef, in which case it will be resolved, or C<undef> (or missing), in
		178	which case the noderef will be guessed.
156		179
157	$node	180	Afterwards, the node will bind itself on all endpoints and try to connect
158	}	181	to all additional C<$seednodes> that are specified. Seednodes are optional
		182	and can be used to quickly bootstrap the node into an existing network.
159		183
		184	=item slave nodes
		185
		186	When the C<$noderef> is the special string C<slave/>, then the node will
		187	become a slave node. Slave nodes cannot be contacted from outside and will
		188	route most of their traffic to the master node that they attach to.
		189
		190	At least one additional noderef is required: The node will try to connect
		191	to all of them and will become a slave attached to the first node it can
		192	successfully connect to.
		193
		194	=back
		195
		196	This function will block until all nodes have been resolved and, for slave
		197	nodes, until it has successfully established a connection to a master
		198	server.
		199
		200	Example: become a public node listening on the default node.
		201
		202	initialise_node;
		203
		204	Example: become a public node, and try to contact some well-known master
		205	servers to become part of the network.
		206
		207	initialise_node undef, "master1", "master2";
		208
		209	Example: become a public node listening on port C<4041>.
		210
		211	initialise_node 4041;
		212
		213	Example: become a public node, only visible on localhost port 4044.
		214
		215	initialise_node "locahost:4044";
		216
		217	Example: become a slave node to any of the specified master servers.
		218
		219	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		220
		221	=item $cv = resolve_node $noderef
		222
		223	Takes an unresolved node reference that may contain hostnames and
		224	abbreviated IDs, resolves all of them and returns a resolved node
		225	reference.
		226
		227	In addition to C<address:port> pairs allowed in resolved noderefs, the
		228	following forms are supported:
		229
		230	=over 4
		231
		232	=item the empty string
		233
		234	An empty-string component gets resolved as if the default port (4040) was
		235	specified.
		236
		237	=item naked port numbers (e.g. C<1234>)
		238
		239	These are resolved by prepending the local nodename and a colon, to be
		240	further resolved.
		241
		242	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		243
		244	These are resolved by using AnyEvent::DNS to resolve them, optionally
		245	looking up SRV records for the C<aemp=4040> port, if no port was
		246	specified.
		247
		248	=back
		249
		250	=item $SELF
		251
		252	Contains the current port id while executing C<rcv> callbacks or C<psub>
		253	blocks.
		254
		255	=item SELF, %SELF, @SELF...
		256
		257	Due to some quirks in how perl exports variables, it is impossible to
		258	just export C<$SELF>, all the symbols called C<SELF> are exported by this
		259	module, but only C<$SELF> is currently used.
		260
160	=item snd $portid, type => @data	261	=item snd $port, type => @data
161		262
162	=item snd $portid, @msg	263	=item snd $port, @msg
163		264
164	Send the given message to the given port ID, which can identify either a	265	Send the given message to the given port ID, which can identify either
165	local or a remote port.	266	a local or a remote port, and can be either a string or soemthignt hat
		267	stringifies a sa port ID (such as a port object :).
166		268
167	While the message can be about anything, it is highly recommended to use	269	While the message can be about anything, it is highly recommended to use a
168	a constant string as first element.	270	string as first element (a portid, or some word that indicates a request
		271	type etc.).
169		272
170	The message data effectively becomes read-only after a call to this	273	The message data effectively becomes read-only after a call to this
171	function: modifying any argument is not allowed and can cause many	274	function: modifying any argument is not allowed and can cause many
172	problems.	275	problems.
173		276
…		…
175	JSON is used, then only strings, numbers and arrays and hashes consisting	278	JSON is used, then only strings, numbers and arrays and hashes consisting
176	of those are allowed (no objects). When Storable is used, then anything	279	of those are allowed (no objects). When Storable is used, then anything
177	that Storable can serialise and deserialise is allowed, and for the local	280	that Storable can serialise and deserialise is allowed, and for the local
178	node, anything can be passed.	281	node, anything can be passed.
179		282
180	=cut	283	=item $local_port = port
181		284
182	sub snd(@) {	285	Create a new local port object that can be used either as a pattern
183	my ($noderef, $port) = split /#/, shift, 2;	286	matching port ("full port") or a single-callback port ("miniport"),
		287	depending on how C<rcv> callbacks are bound to the object.
184		288
185	add_node $noderef	289	=item $port = port { my @msg = @_; $finished }
186	unless exists $NODE{$noderef};
187		290
188	$NODE{$noderef}->send (["$port", [@_]]);	291	Creates a "miniport", that is, a very lightweight port without any pattern
		292	matching behind it, and returns its ID. Semantically the same as creating
		293	a port and calling C<rcv $port, $callback> on it.
		294
		295	The block will be called for every message received on the port. When the
		296	callback returns a true value its job is considered "done" and the port
		297	will be destroyed. Otherwise it will stay alive.
		298
		299	The message will be passed as-is, no extra argument (i.e. no port id) will
		300	be passed to the callback.
		301
		302	If you need the local port id in the callback, this works nicely:
		303
		304	my $port; $port = port {
		305	snd $otherport, reply => $port;
		306	};
		307
		308	=cut
		309
		310	sub rcv($@);
		311
		312	sub port(;&) {
		313	my $id = "$UNIQ." . $ID++;
		314	my $port = "$NODE#$id";
		315
		316	if (@_) {
		317	rcv $port, shift;
		318	} else {
		319	$PORT{$id} = sub { }; # nop
		320	}
		321
		322	$port
189	}	323	}
190		324
		325	=item reg $port, $name
		326
		327	=item reg $name
		328
		329	Registers the given port (or C<$SELF><<< if missing) under the name
		330	C<$name>. If the name already exists it is replaced.
		331
		332	A port can only be registered under one well known name.
		333
		334	A port automatically becomes unregistered when it is killed.
		335
		336	=cut
		337
		338	sub reg(@) {
		339	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
		340
		341	$REG{$_[0]} = $port;
		342	}
		343
191	=item rcv $portid, type => $callback->(@msg)	344	=item rcv $port, $callback->(@msg)
192		345
		346	Replaces the callback on the specified miniport (after converting it to
		347	one if required).
		348
		349	=item rcv $port, tagstring => $callback->(@msg), ...
		350
193	=item rcv $portid, $smartmatch => $callback->(@msg)	351	=item rcv $port, $smartmatch => $callback->(@msg), ...
194		352
195	=item rcv $portid, [$smartmatch...] => $callback->(@msg)	353	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
196		354
197	Register a callback on the port identified by C<$portid>, which I<must> be	355	Register callbacks to be called on matching messages on the given full
198	a local port.	356	port (after converting it to one if required) and return the port.
199		357
200	The callback has to return a true value when its work is done, after	358	The callback has to return a true value when its work is done, after
201	which is will be removed, or a false value in which case it will stay	359	which is will be removed, or a false value in which case it will stay
202	registered.	360	registered.
203		361
		362	The global C<$SELF> (exported by this module) contains C<$port> while
		363	executing the callback.
		364
		365	Runtime errors during callback execution will result in the port being
		366	C<kil>ed.
		367
204	If the match is an array reference, then it will be matched against the	368	If the match is an array reference, then it will be matched against the
205	first elements of the message, otherwise only the first element is being	369	first elements of the message, otherwise only the first element is being
206	matched.	370	matched.
207		371
208	Any element in the match that is specified as C<_any_> (a function	372	Any element in the match that is specified as C<_any_> (a function
…		…
210		374
211	While not required, it is highly recommended that the first matching	375	While not required, it is highly recommended that the first matching
212	element is a string identifying the message. The one-string-only match is	376	element is a string identifying the message. The one-string-only match is
213	also the most efficient match (by far).	377	also the most efficient match (by far).
214		378
		379	Example: create a port and bind receivers on it in one go.
		380
		381	my $port = rcv port,
		382	msg1 => sub { ...; 0 },
		383	msg2 => sub { ...; 0 },
		384	;
		385
		386	Example: create a port, bind receivers and send it in a message elsewhere
		387	in one go:
		388
		389	snd $otherport, reply =>
		390	rcv port,
		391	msg1 => sub { ...; 0 },
		392	...
		393	;
		394
215	=cut	395	=cut
216		396
217	sub rcv($@) {	397	sub rcv($@) {
218	my ($port, $match, $cb) = @_;	398	my $port = shift;
219
220	my $port = $PORT{$port}
221	or do {
222	my ($noderef, $lport) = split /#/, $port;	399	my ($noderef, $portid) = split /#/, $port, 2;
223	"AnyEvent::MP::Node::Self" eq ref $NODE{$noderef}	400
		401	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
224	or Carp::croak "$port: can only rcv on local ports";	402	or Carp::croak "$port: rcv can only be called on local ports, caught";
225		403
226	$PORT{$lport}	404	if (@_ == 1) {
227	or Carp::croak "$port: port does not exist";	405	my $cb = shift;
		406	delete $PORT_DATA{$portid};
		407	$PORT{$portid} = sub {
		408	local $SELF = $port;
		409	eval {
228		410	&$cb
229	$PORT{$port} = $PORT{$lport} # also return	411	and kil $port;
		412	};
		413	_self_die if $@;
230	};	414	};
231
232	if (!ref $match) {
233	push @{ $port->{rc0}{$match} }, [$cb];
234	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
235	my ($type, @match) = @$match;
236	@match
237	? push @{ $port->{rcv}{$match->[0]} }, [$cb, \@match]
238	: push @{ $port->{rc0}{$match->[0]} }, [$cb];
239	} else {	415	} else {
240	push @{ $port->{any} }, [$cb, $match];	416	my $self = $PORT_DATA{$portid} \|\|= do {
241	}	417	my $self = bless {
242	}	418	id => $port,
		419	}, "AnyEvent::MP::Port";
243		420
244	sub _inject {	421	$PORT{$portid} = sub {
245	my ($port, $msg) = @{+shift};	422	local $SELF = $port;
246		423
247	$port = $PORT{$port}	424	eval {
248	or return;	425	for (@{ $self->{rc0}{$_[0]} }) {
249
250	@_ = @$msg;
251
252	for (@{ $port->{rc0}{$msg->[0]} }) {
253	$_ && &{$_->[0]}	426	$_ && &{$_->[0]}
254	&& undef $_;	427	&& undef $_;
255	}
256
257	for (@{ $port->{rcv}{$msg->[0]} }) {
258	$_ && [@_[1..$#{$_->[1]}]] ~~ $_->[1]
259	&& &{$_->[0]}
260	&& undef $_;
261	}
262
263	for (@{ $port->{any} }) {
264	$_ && [@_[0..$#{$_->[1]}]] ~~ $_->[1]
265	&& &{$_->[0]}
266	&& undef $_;
267	}
268	}
269
270	sub normalise_noderef($) {
271	my ($noderef) = @_;
272
273	my $cv = AE::cv;
274	my @res;
275
276	$cv->begin (sub {
277	my %seen;
278	my @refs;
279	for (sort { $a->[0] <=> $b->[0] } @res) {
280	push @refs, $_->[1] unless $seen{$_->[1]}++
281	}
282	shift->send (join ",", @refs);
283	});
284
285	$noderef = $DEFAULT_PORT unless length $noderef;
286
287	my $idx;
288	for my $t (split /,/, $noderef) {
289	my $pri = ++$idx;
290
291	#TODO: this should be outside normalise_noderef and in become_public
292	if ($t =~ /^\d*$/) {
293	my $nodename = (POSIX::uname)[1];
294
295	$cv->begin;
296	AnyEvent::Socket::resolve_sockaddr $nodename, $t \|\| "aemp=$DEFAULT_PORT", "tcp", 0, undef, sub {
297	for (@_) {
298	my ($service, $host) = AnyEvent::Socket::unpack_sockaddr $_->[3];
299	push @res, [
300	$pri += 1e-5,
301	AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $host, $service
302	];	428	}
		429
		430	for (@{ $self->{rcv}{$_[0]} }) {
		431	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
		432	&& &{$_->[0]}
		433	&& undef $_;
		434	}
		435
		436	for (@{ $self->{any} }) {
		437	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
		438	&& &{$_->[0]}
		439	&& undef $_;
		440	}
303	}	441	};
304	$cv->end;	442	_self_die if $@;
305	};	443	};
306		444
307	# my (undef, undef, undef, undef, @ipv4) = gethostbyname $nodename;	445	$self
308	#	446	};
309	# for (@ipv4) {	447
310	# push @res, [	448	"AnyEvent::MP::Port" eq ref $self
311	# $pri,	449	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
312	# AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $_, $t \|\| $DEFAULT_PORT,	450
313	# ];	451	while (@_) {
314	# }	452	my ($match, $cb) = splice @_, 0, 2;
		453
		454	if (!ref $match) {
		455	push @{ $self->{rc0}{$match} }, [$cb];
		456	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
		457	my ($type, @match) = @$match;
		458	@match
		459	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
		460	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
315	} else {	461	} else {
316	my ($host, $port) = AnyEvent::Socket::parse_hostport $t, "aemp=$DEFAULT_PORT"	462	push @{ $self->{any} }, [$cb, $match];
317	or Carp::croak "$t: unparsable transport descriptor";
318
319	$cv->begin;
320	AnyEvent::Socket::resolve_sockaddr $host, $port, "tcp", 0, undef, sub {
321	for (@_) {
322	my ($service, $host) = AnyEvent::Socket::unpack_sockaddr $_->[3];
323	push @res, [
324	$pri += 1e-5,
325	AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $host, $service
326	];
327	}
328	$cv->end;
329	}	463	}
330	}	464	}
331	}	465	}
332		466
333	$cv->end;	467	$port
334
335	$cv
336	}	468	}
337		469
338	sub become_public {	470	=item $closure = psub { BLOCK }
339	return if $PUBLIC;
340		471
341	my $noderef = join ",", ref $_[0] ? @{+shift} : shift;	472	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
342	my @args = @_;	473	closure is executed, sets up the environment in the same way as in C<rcv>
		474	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
343		475
344	$NODE = (normalise_noderef $noderef)->recv;	476	This is useful when you register callbacks from C<rcv> callbacks:
345		477
346	for my $t (split /,/, $NODE) {	478	rcv delayed_reply => sub {
347	$NODE{$t} = $NODE{""};	479	my ($delay, @reply) = @_;
348		480	my $timer = AE::timer $delay, 0, psub {
349	my ($host, $port) = AnyEvent::Socket::parse_hostport $t;	481	snd @reply, $SELF;
350
351	$LISTENER{$t} = AnyEvent::MP::Transport::mp_server $host, $port,
352	@args,
353	on_error => sub {
354	die "on_error<@_>\n";#d#
355	},
356	on_connect => sub {
357	my ($tp) = @_;
358
359	$NODE{$tp->{remote_id}} = $_[0];
360	},
361	sub {
362	my ($tp) = @_;
363
364	$NODE{"$tp->{peerhost}:$tp->{peerport}"} = $tp;
365	},
366	;	482	};
		483	};
		484
		485	=cut
		486
		487	sub psub(&) {
		488	my $cb = shift;
		489
		490	my $port = $SELF
		491	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		492
		493	sub {
		494	local $SELF = $port;
		495
		496	if (wantarray) {
		497	my @res = eval { &$cb };
		498	_self_die if $@;
		499	@res
		500	} else {
		501	my $res = eval { &$cb };
		502	_self_die if $@;
		503	$res
		504	}
367	}	505	}
		506	}
368		507
369	$PUBLIC = 1;	508	=item $guard = mon $port, $cb->(@reason)
		509
		510	=item $guard = mon $port, $rcvport
		511
		512	=item $guard = mon $port
		513
		514	=item $guard = mon $port, $rcvport, @msg
		515
		516	Monitor the given port and do something when the port is killed or
		517	messages to it were lost, and optionally return a guard that can be used
		518	to stop monitoring again.
		519
		520	C<mon> effectively guarantees that, in the absence of hardware failures,
		521	that after starting the monitor, either all messages sent to the port
		522	will arrive, or the monitoring action will be invoked after possible
		523	message loss has been detected. No messages will be lost "in between"
		524	(after the first lost message no further messages will be received by the
		525	port). After the monitoring action was invoked, further messages might get
		526	delivered again.
		527
		528	In the first form (callback), the callback is simply called with any
		529	number of C<@reason> elements (no @reason means that the port was deleted
		530	"normally"). Note also that I<< the callback B<must> never die >>, so use
		531	C<eval> if unsure.
		532
		533	In the second form (another port given), the other port (C<$rcvport>)
		534	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		535	"normal" kils nothing happens, while under all other conditions, the other
		536	port is killed with the same reason.
		537
		538	The third form (kill self) is the same as the second form, except that
		539	C<$rvport> defaults to C<$SELF>.
		540
		541	In the last form (message), a message of the form C<@msg, @reason> will be
		542	C<snd>.
		543
		544	As a rule of thumb, monitoring requests should always monitor a port from
		545	a local port (or callback). The reason is that kill messages might get
		546	lost, just like any other message. Another less obvious reason is that
		547	even monitoring requests can get lost (for exmaple, when the connection
		548	to the other node goes down permanently). When monitoring a port locally
		549	these problems do not exist.
		550
		551	Example: call a given callback when C<$port> is killed.
		552
		553	mon $port, sub { warn "port died because of <@_>\n" };
		554
		555	Example: kill ourselves when C<$port> is killed abnormally.
		556
		557	mon $port;
		558
		559	Example: send us a restart message when another C<$port> is killed.
		560
		561	mon $port, $self => "restart";
		562
		563	=cut
		564
		565	sub mon {
		566	my ($noderef, $port) = split /#/, shift, 2;
		567
		568	my $node = $NODE{$noderef} \|\| add_node $noderef;
		569
		570	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		571
		572	unless (ref $cb) {
		573	if (@_) {
		574	# send a kill info message
		575	my (@msg) = ($cb, @_);
		576	$cb = sub { snd @msg, @_ };
		577	} else {
		578	# simply kill other port
		579	my $port = $cb;
		580	$cb = sub { kil $port, @_ if @_ };
		581	}
		582	}
		583
		584	$node->monitor ($port, $cb);
		585
		586	defined wantarray
		587	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		588	}
		589
		590	=item $guard = mon_guard $port, $ref, $ref...
		591
		592	Monitors the given C<$port> and keeps the passed references. When the port
		593	is killed, the references will be freed.
		594
		595	Optionally returns a guard that will stop the monitoring.
		596
		597	This function is useful when you create e.g. timers or other watchers and
		598	want to free them when the port gets killed:
		599
		600	$port->rcv (start => sub {
		601	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		602	undef $timer if 0.9 < rand;
		603	});
		604	});
		605
		606	=cut
		607
		608	sub mon_guard {
		609	my ($port, @refs) = @_;
		610
		611	#TODO: mon-less form?
		612
		613	mon $port, sub { 0 && @refs }
		614	}
		615
		616	=item kil $port[, @reason]
		617
		618	Kill the specified port with the given C<@reason>.
		619
		620	If no C<@reason> is specified, then the port is killed "normally" (linked
		621	ports will not be kileld, or even notified).
		622
		623	Otherwise, linked ports get killed with the same reason (second form of
		624	C<mon>, see below).
		625
		626	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		627	will be reported as reason C<< die => $@ >>.
		628
		629	Transport/communication errors are reported as C<< transport_error =>
		630	$message >>.
		631
		632	=cut
		633
		634	=item $port = spawn $node, $initfunc[, @initdata]
		635
		636	Creates a port on the node C<$node> (which can also be a port ID, in which
		637	case it's the node where that port resides).
		638
		639	The port ID of the newly created port is return immediately, and it is
		640	permissible to immediately start sending messages or monitor the port.
		641
		642	After the port has been created, the init function is
		643	called. This function must be a fully-qualified function name
		644	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		645	program, use C<::name>.
		646
		647	If the function doesn't exist, then the node tries to C<require>
		648	the package, then the package above the package and so on (e.g.
		649	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		650	exists or it runs out of package names.
		651
		652	The init function is then called with the newly-created port as context
		653	object (C<$SELF>) and the C<@initdata> values as arguments.
		654
		655	A common idiom is to pass your own port, monitor the spawned port, and
		656	in the init function, monitor the original port. This two-way monitoring
		657	ensures that both ports get cleaned up when there is a problem.
		658
		659	Example: spawn a chat server port on C<$othernode>.
		660
		661	# this node, executed from within a port context:
		662	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		663	mon $server;
		664
		665	# init function on C<$othernode>
		666	sub connect {
		667	my ($srcport) = @_;
		668
		669	mon $srcport;
		670
		671	rcv $SELF, sub {
		672	...
		673	};
		674	}
		675
		676	=cut
		677
		678	sub _spawn {
		679	my $port = shift;
		680	my $init = shift;
		681
		682	local $SELF = "$NODE#$port";
		683	eval {
		684	&{ load_func $init }
		685	};
		686	_self_die if $@;
		687	}
		688
		689	sub spawn(@) {
		690	my ($noderef, undef) = split /#/, shift, 2;
		691
		692	my $id = "$RUNIQ." . $ID++;
		693
		694	$_[0] =~ /::/
		695	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		696
		697	($NODE{$noderef} \|\| add_node $noderef)
		698	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		699
		700	"$noderef#$id"
370	}	701	}
371		702
372	=back	703	=back
373		704
374	=head1 NODE MESSAGES	705	=head1 NODE MESSAGES
…		…
376	Nodes understand the following messages sent to them. Many of them take	707	Nodes understand the following messages sent to them. Many of them take
377	arguments called C<@reply>, which will simply be used to compose a reply	708	arguments called C<@reply>, which will simply be used to compose a reply
378	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	709	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
379	the remaining arguments are simply the message data.	710	the remaining arguments are simply the message data.
380		711
		712	While other messages exist, they are not public and subject to change.
		713
381	=over 4	714	=over 4
382		715
383	=cut	716	=cut
384		717
385	#############################################################################	718	=item lookup => $name, @reply
386	# self node code
387		719
388	sub _new_port($) {	720	Replies with the port ID of the specified well-known port, or C<undef>.
389	my ($name) = @_;
390
391	my ($noderef, $portname) = split /#/, $name;
392
393	$PORT{$name} =
394	$PORT{$portname} = {
395	names => [$name, $portname],
396	};
397	}
398
399	$NODE{""} = new AnyEvent::MP::Node::Self noderef => $NODE;
400	_new_port "";
401		721
402	=item devnull => ...	722	=item devnull => ...
403		723
404	Generic data sink/CPU heat conversion.	724	Generic data sink/CPU heat conversion.
405		725
406	=cut
407
408	rcv "", devnull => sub { () };
409
410	=item relay => $port, @msg	726	=item relay => $port, @msg
411		727
412	Simply forwards the message to the given port.	728	Simply forwards the message to the given port.
413
414	=cut
415
416	rcv "", relay => sub { \&snd; () };
417		729
418	=item eval => $string[ @reply]	730	=item eval => $string[ @reply]
419		731
420	Evaluates the given string. If C<@reply> is given, then a message of the	732	Evaluates the given string. If C<@reply> is given, then a message of the
421	form C<@reply, $@, @evalres> is sent.	733	form C<@reply, $@, @evalres> is sent.
422		734
423	Example: crash another node.	735	Example: crash another node.
424		736
425	snd $othernode, eval => "exit";	737	snd $othernode, eval => "exit";
426		738
427	=cut
428
429	rcv "", eval => sub {
430	my (undef, $string, @reply) = @_;
431	my @res = eval $string;
432	snd @reply, "$@", @res if @reply;
433	()
434	};
435
436	=item time => @reply	739	=item time => @reply
437		740
438	Replies the the current node time to C<@reply>.	741	Replies the the current node time to C<@reply>.
439		742
440	Example: tell the current node to send the current time to C<$myport> in a	743	Example: tell the current node to send the current time to C<$myport> in a
441	C<timereply> message.	744	C<timereply> message.
442		745
443	snd $NODE, time => $myport, timereply => 1, 2;	746	snd $NODE, time => $myport, timereply => 1, 2;
444	# => snd $myport, timereply => 1, 2, <time>	747	# => snd $myport, timereply => 1, 2, <time>
445		748
446	=cut	749	=back
447		750
448	rcv "", time => sub { shift; snd @_, AE::time; () };	751	=head1 AnyEvent::MP vs. Distributed Erlang
		752
		753	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		754	== aemp node, Erlang process == aemp port), so many of the documents and
		755	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		756	sample:
		757
		758	http://www.Erlang.se/doc/programming_rules.shtml
		759	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		760	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		761	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		762
		763	Despite the similarities, there are also some important differences:
		764
		765	=over 4
		766
		767	=item * Node references contain the recipe on how to contact them.
		768
		769	Erlang relies on special naming and DNS to work everywhere in the
		770	same way. AEMP relies on each node knowing it's own address(es), with
		771	convenience functionality.
		772
		773	This means that AEMP requires a less tightly controlled environment at the
		774	cost of longer node references and a slightly higher management overhead.
		775
		776	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		777
		778	Erlang uses processes that selctively receive messages, and therefore
		779	needs a queue. AEMP is event based, queuing messages would serve no useful
		780	purpose.
		781
		782	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		783
		784	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		785
		786	Sending messages in Erlang is synchronous and blocks the process. AEMP
		787	sends are immediate, connection establishment is handled in the
		788	background.
		789
		790	=item * Erlang can silently lose messages, AEMP cannot.
		791
		792	Erlang makes few guarantees on messages delivery - messages can get lost
		793	without any of the processes realising it (i.e. you send messages a, b,
		794	and c, and the other side only receives messages a and c).
		795
		796	AEMP guarantees correct ordering, and the guarantee that there are no
		797	holes in the message sequence.
		798
		799	=item * In Erlang, processes can be declared dead and later be found to be
		800	alive.
		801
		802	In Erlang it can happen that a monitored process is declared dead and
		803	linked processes get killed, but later it turns out that the process is
		804	still alive - and can receive messages.
		805
		806	In AEMP, when port monitoring detects a port as dead, then that port will
		807	eventually be killed - it cannot happen that a node detects a port as dead
		808	and then later sends messages to it, finding it is still alive.
		809
		810	=item * Erlang can send messages to the wrong port, AEMP does not.
		811
		812	In Erlang it is quite possible that a node that restarts reuses a process
		813	ID known to other nodes for a completely different process, causing
		814	messages destined for that process to end up in an unrelated process.
		815
		816	AEMP never reuses port IDs, so old messages or old port IDs floating
		817	around in the network will not be sent to an unrelated port.
		818
		819	=item * Erlang uses unprotected connections, AEMP uses secure
		820	authentication and can use TLS.
		821
		822	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		823	securely authenticate nodes.
		824
		825	=item * The AEMP protocol is optimised for both text-based and binary
		826	communications.
		827
		828	The AEMP protocol, unlike the Erlang protocol, supports both
		829	language-independent text-only protocols (good for debugging) and binary,
		830	language-specific serialisers (e.g. Storable).
		831
		832	It has also been carefully designed to be implementable in other languages
		833	with a minimum of work while gracefully degrading fucntionality to make the
		834	protocol simple.
		835
		836	=item * AEMP has more flexible monitoring options than Erlang.
		837
		838	In Erlang, you can chose to receive I<all> exit signals as messages
		839	or I<none>, there is no in-between, so monitoring single processes is
		840	difficult to implement. Monitoring in AEMP is more flexible than in
		841	Erlang, as one can choose between automatic kill, exit message or callback
		842	on a per-process basis.
		843
		844	=item * Erlang tries to hide remote/local connections, AEMP does not.
		845
		846	Monitoring in Erlang is not an indicator of process death/crashes,
		847	as linking is (except linking is unreliable in Erlang).
		848
		849	In AEMP, you don't "look up" registered port names or send to named ports
		850	that might or might not be persistent. Instead, you normally spawn a port
		851	on the remote node. The init function monitors the you, and you monitor
		852	the remote port. Since both monitors are local to the node, they are much
		853	more reliable.
		854
		855	This also saves round-trips and avoids sending messages to the wrong port
		856	(hard to do in Erlang).
		857
		858	=back
		859
		860	=head1 RATIONALE
		861
		862	=over 4
		863
		864	=item Why strings for ports and noderefs, why not objects?
		865
		866	We considered "objects", but found that the actual number of methods
		867	thatc an be called are very low. Since port IDs and noderefs travel over
		868	the network frequently, the serialising/deserialising would add lots of
		869	overhead, as well as having to keep a proxy object.
		870
		871	Strings can easily be printed, easily serialised etc. and need no special
		872	procedures to be "valid".
		873
		874	=item Why favour JSON, why not real serialising format such as Storable?
		875
		876	In fact, any AnyEvent::MP node will happily accept Storable as framing
		877	format, but currently there is no way to make a node use Storable by
		878	default.
		879
		880	The default framing protocol is JSON because a) JSON::XS is many times
		881	faster for small messages and b) most importantly, after years of
		882	experience we found that object serialisation is causing more problems
		883	than it gains: Just like function calls, objects simply do not travel
		884	easily over the network, mostly because they will always be a copy, so you
		885	always have to re-think your design.
		886
		887	Keeping your messages simple, concentrating on data structures rather than
		888	objects, will keep your messages clean, tidy and efficient.
449		889
450	=back	890	=back
451		891
452	=head1 SEE ALSO	892	=head1 SEE ALSO
453		893

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Revision 1.7 by root, Sat Aug 1 15:04:30 2009 UTC vs.
Revision 1.46 by root, Thu Aug 13 01:46:10 2009 UTC