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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.2 by root, Fri Jul 31 20:55:46 2009 UTC vs.
Revision 1.37 by root, Fri Aug 7 16:47:23 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
12	snd $port, type => data...;	13	snd $port, type => data...;
		14
		15	$SELF # receiving/own port id in rcv callbacks
13		16
14	rcv $port, smartmatch => $cb->($port, @msg);	17	rcv $port, smartmatch => $cb->($port, @msg);
15		18
16	# examples:	19	# examples:
17	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };
…		…
20		23
21	# more, smarter, matches (_any_ is exported by this module)	24	# more, smarter, matches (_any_ is exported by this module)
22	rcv $port, [child_died => $pid] => sub { ...	25	rcv $port, [child_died => $pid] => sub { ...
23	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
24		27
		28	# monitoring
		29	mon $port, $cb->(@msg) # callback is invoked on death
		30	mon $port, $otherport # kill otherport on abnormal death
		31	mon $port, $otherport, @msg # send message on death
		32
25	=head1 DESCRIPTION	33	=head1 DESCRIPTION
26		34
27	This module (-family) implements a simple message passing framework.	35	This module (-family) implements a simple message passing framework.
28		36
29	Despite its simplicity, you can securely message other processes running	37	Despite its simplicity, you can securely message other processes running
30	on the same or other hosts.	38	on the same or other hosts.
31		39
		40	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		41	manual page.
		42
		43	At the moment, this module family is severly broken and underdocumented,
		44	so do not use. This was uploaded mainly to reserve the CPAN namespace -
		45	stay tuned! The basic API should be finished, however.
		46
32	=head1 CONCEPTS	47	=head1 CONCEPTS
33		48
34	=over 4	49	=over 4
35		50
36	=item port	51	=item port
37		52
38	A port is something you can send messages to with the C<snd> function, and	53	A port is something you can send messages to (with the C<snd> function).
39	you can register C<rcv> handlers with. All C<rcv> handlers will receive
40	messages they match, messages will not be queued.
41		54
		55	Some ports allow you to register C<rcv> handlers that can match specific
		56	messages. All C<rcv> handlers will receive messages they match, messages
		57	will not be queued.
		58
42	=item port id - C<pid@host#portname>	59	=item port id - C<noderef#portname>
43		60
44	A port id is always the node id, a hash-mark (C<#>) as separator, followed	61	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as
45	by a port name.	62	separator, and a port name (a printable string of unspecified format). An
46		63	exception is the the node port, whose ID is identical to its node
47	A port name can be a well known port (basically an identifier/bareword),	64	reference.
48	or a generated name, consisting of node id, a dot (C<.>), and an
49	identifier.
50		65
51	=item node	66	=item node
52		67
53	A node is a single process containing at least one port - the node	68	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,	69	port. You can send messages to node ports to find existing ports or to
55	among other things.	70	create new ports, among other things.
56		71
57	Initially, nodes are either private (single-process only) or hidden	72	Nodes are either private (single-process only), slaves (connected to a
58	(connected to a father node only). Only when they epxlicitly "go public"	73	master node only) or public nodes (connectable from unrelated nodes).
59	can you send them messages form unrelated other nodes.
60		74
61	Public nodes automatically connect to all other public nodes in a network	75	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
62	when they connect, creating a full mesh.
63		76
64	=item node id - C<host:port>, C<id@host>, C<id>
65
66	A node ID is a string that either uniquely identifies a given node (For	77	A node reference is a string that either simply identifies the node (for
67	private and hidden nodes), or contains a recipe on how to reach a given	78	private and slave nodes), or contains a recipe on how to reach a given
68	node (for public nodes).	79	node (for public nodes).
69		80
		81	This recipe is simply a comma-separated list of C<address:port> pairs (for
		82	TCP/IP, other protocols might look different).
		83
		84	Node references come in two flavours: resolved (containing only numerical
		85	addresses) or unresolved (where hostnames are used instead of addresses).
		86
		87	Before using an unresolved node reference in a message you first have to
		88	resolve it.
		89
70	=back	90	=back
71		91
72	=head1 FUNCTIONS	92	=head1 VARIABLES/FUNCTIONS
73		93
74	=over 4	94	=over 4
75		95
76	=cut	96	=cut
77		97
78	package AnyEvent::MP;	98	package AnyEvent::MP;
79		99
80	use AnyEvent::MP::Util ();
81	use AnyEvent::MP::Node;	100	use AnyEvent::MP::Base;
82	use AnyEvent::MP::Transport;
83		101
84	use utf8;
85	use common::sense;	102	use common::sense;
86		103
87	use Carp ();	104	use Carp ();
88		105
89	use AE ();	106	use AE ();
90		107
91	use base "Exporter";	108	use base "Exporter";
92		109
93	our $VERSION = '0.0';	110	our $VERSION = '0.1';
94	our @EXPORT = qw(NODE $NODE $PORT snd rcv _any_);	111	our @EXPORT = qw(
		112	NODE $NODE *SELF node_of _any_
		113	resolve_node initialise_node
		114	snd rcv mon kil reg psub
		115	port
		116	);
95		117
96	our $DEFAULT_SECRET;	118	our $SELF;
97	our $DEFAULT_PORT = "4040";
98		119
99	our $CONNECT_INTERVAL = 5; # new connect every 5s, at least	120	sub _self_die() {
100	our $CONNECT_TIMEOUT = 30; # includes handshake	121	my $msg = $@;
		122	$msg =~ s/\n+$// unless ref $msg;
		123	kil $SELF, die => $msg;
		124	}
101		125
102	sub default_secret {	126	=item $thisnode = NODE / $NODE
103	unless (defined $DEFAULT_SECRET) {	127
104	if (open my $fh, "<$ENV{HOME}/.aemp-secret") {	128	The C<NODE> function returns, and the C<$NODE> variable contains
105	sysread $fh, $DEFAULT_SECRET, -s $fh;	129	the noderef of the local node. The value is initialised by a call
		130	to C<become_public> or C<become_slave>, after which all local port
		131	identifiers become invalid.
		132
		133	=item $noderef = node_of $port
		134
		135	Extracts and returns the noderef from a portid or a noderef.
		136
		137	=item initialise_node $noderef, $seednode, $seednode...
		138
		139	=item initialise_node "slave/", $master, $master...
		140
		141	Before a node can talk to other nodes on the network it has to initialise
		142	itself - the minimum a node needs to know is it's own name, and optionally
		143	it should know the noderefs of some other nodes in the network.
		144
		145	This function initialises a node - it must be called exactly once (or
		146	never) before calling other AnyEvent::MP functions.
		147
		148	All arguments are noderefs, which can be either resolved or unresolved.
		149
		150	There are two types of networked nodes, public nodes and slave nodes:
		151
		152	=over 4
		153
		154	=item public nodes
		155
		156	For public nodes, C<$noderef> must either be a (possibly unresolved)
		157	noderef, in which case it will be resolved, or C<undef> (or missing), in
		158	which case the noderef will be guessed.
		159
		160	Afterwards, the node will bind itself on all endpoints and try to connect
		161	to all additional C<$seednodes> that are specified. Seednodes are optional
		162	and can be used to quickly bootstrap the node into an existing network.
		163
		164	=item slave nodes
		165
		166	When the C<$noderef> is the special string C<slave/>, then the node will
		167	become a slave node. Slave nodes cannot be contacted from outside and will
		168	route most of their traffic to the master node that they attach to.
		169
		170	At least one additional noderef is required: The node will try to connect
		171	to all of them and will become a slave attached to the first node it can
		172	successfully connect to.
		173
		174	=back
		175
		176	This function will block until all nodes have been resolved and, for slave
		177	nodes, until it has successfully established a connection to a master
		178	server.
		179
		180	Example: become a public node listening on the default node.
		181
		182	initialise_node;
		183
		184	Example: become a public node, and try to contact some well-known master
		185	servers to become part of the network.
		186
		187	initialise_node undef, "master1", "master2";
		188
		189	Example: become a public node listening on port C<4041>.
		190
		191	initialise_node 4041;
		192
		193	Example: become a public node, only visible on localhost port 4044.
		194
		195	initialise_node "locahost:4044";
		196
		197	Example: become a slave node to any of the specified master servers.
		198
		199	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		200
		201	=item $cv = resolve_node $noderef
		202
		203	Takes an unresolved node reference that may contain hostnames and
		204	abbreviated IDs, resolves all of them and returns a resolved node
		205	reference.
		206
		207	In addition to C<address:port> pairs allowed in resolved noderefs, the
		208	following forms are supported:
		209
		210	=over 4
		211
		212	=item the empty string
		213
		214	An empty-string component gets resolved as if the default port (4040) was
		215	specified.
		216
		217	=item naked port numbers (e.g. C<1234>)
		218
		219	These are resolved by prepending the local nodename and a colon, to be
		220	further resolved.
		221
		222	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		223
		224	These are resolved by using AnyEvent::DNS to resolve them, optionally
		225	looking up SRV records for the C<aemp=4040> port, if no port was
		226	specified.
		227
		228	=back
		229
		230	=item $SELF
		231
		232	Contains the current port id while executing C<rcv> callbacks or C<psub>
		233	blocks.
		234
		235	=item SELF, %SELF, @SELF...
		236
		237	Due to some quirks in how perl exports variables, it is impossible to
		238	just export C<$SELF>, all the symbols called C<SELF> are exported by this
		239	module, but only C<$SELF> is currently used.
		240
		241	=item snd $port, type => @data
		242
		243	=item snd $port, @msg
		244
		245	Send the given message to the given port ID, which can identify either
		246	a local or a remote port, and can be either a string or soemthignt hat
		247	stringifies a sa port ID (such as a port object :).
		248
		249	While the message can be about anything, it is highly recommended to use a
		250	string as first element (a portid, or some word that indicates a request
		251	type etc.).
		252
		253	The message data effectively becomes read-only after a call to this
		254	function: modifying any argument is not allowed and can cause many
		255	problems.
		256
		257	The type of data you can transfer depends on the transport protocol: when
		258	JSON is used, then only strings, numbers and arrays and hashes consisting
		259	of those are allowed (no objects). When Storable is used, then anything
		260	that Storable can serialise and deserialise is allowed, and for the local
		261	node, anything can be passed.
		262
		263	=item $local_port = port
		264
		265	Create a new local port object that can be used either as a pattern
		266	matching port ("full port") or a single-callback port ("miniport"),
		267	depending on how C<rcv> callbacks are bound to the object.
		268
		269	=item $port = port { my @msg = @_; $finished }
		270
		271	Creates a "miniport", that is, a very lightweight port without any pattern
		272	matching behind it, and returns its ID. Semantically the same as creating
		273	a port and calling C<rcv $port, $callback> on it.
		274
		275	The block will be called for every message received on the port. When the
		276	callback returns a true value its job is considered "done" and the port
		277	will be destroyed. Otherwise it will stay alive.
		278
		279	The message will be passed as-is, no extra argument (i.e. no port id) will
		280	be passed to the callback.
		281
		282	If you need the local port id in the callback, this works nicely:
		283
		284	my $port; $port = port {
		285	snd $otherport, reply => $port;
		286	};
		287
		288	=cut
		289
		290	sub rcv($@);
		291
		292	sub port(;&) {
		293	my $id = "$UNIQ." . $ID++;
		294	my $port = "$NODE#$id";
		295
		296	if (@_) {
		297	rcv $port, shift;
106	} else {	298	} else {
107	$DEFAULT_SECRET = AnyEvent::MP::Util::nonce 32;	299	$PORT{$id} = sub { }; # nop
108	}
109	}	300	}
110		301
111	$DEFAULT_SECRET	302	$port
112	}	303	}
113		304
114	our $UNIQ = sprintf "%x.%x", $$, time; # per-process/node unique cookie	305	=item reg $port, $name
115	our $PUBLIC = 0;
116	our $NODE;
117	our $PORT;
118		306
119	our %NODE; # node id to transport mapping, or "undef", for local node	307	=item reg $name
120	our %PORT; # local ports
121	our %LISTENER; # local transports
122		308
123	sub NODE() { $NODE }	309	Registers the given port (or C<$SELF><<< if missing) under the name
		310	C<$name>. If the name already exists it is replaced.
124		311
125	{	312	A port can only be registered under one well known name.
126	use POSIX ();	313
127	my $nodename = (POSIX::uname)[1];	314	A port automatically becomes unregistered when it is killed.
128	$NODE = "$$\@$nodename";	315
		316	=cut
		317
		318	sub reg(@) {
		319	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
		320
		321	$REG{$_[0]} = $port;
129	}	322	}
130		323
131	sub _ANY_() { 1 }	324	=item rcv $port, $callback->(@msg)
132	sub _any_() { \&_ANY_ }
133		325
134	sub add_node {	326	Replaces the callback on the specified miniport (after converting it to
135	my ($noderef) = @_;	327	one if required).
136		328
137	return $NODE{$noderef}	329	=item rcv $port, tagstring => $callback->(@msg), ...
138	if exists $NODE{$noderef};
139		330
140	for (split /,/, $noderef) {	331	=item rcv $port, $smartmatch => $callback->(@msg), ...
141	return $NODE{$noderef} = $NODE{$_}	332
142	if exists $NODE{$_};	333	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		334
		335	Register callbacks to be called on matching messages on the given full
		336	port (after converting it to one if required) and return the port.
		337
		338	The callback has to return a true value when its work is done, after
		339	which is will be removed, or a false value in which case it will stay
		340	registered.
		341
		342	The global C<$SELF> (exported by this module) contains C<$port> while
		343	executing the callback.
		344
		345	Runtime errors wdurign callback execution will result in the port being
		346	C<kil>ed.
		347
		348	If the match is an array reference, then it will be matched against the
		349	first elements of the message, otherwise only the first element is being
		350	matched.
		351
		352	Any element in the match that is specified as C<_any_> (a function
		353	exported by this module) matches any single element of the message.
		354
		355	While not required, it is highly recommended that the first matching
		356	element is a string identifying the message. The one-string-only match is
		357	also the most efficient match (by far).
		358
		359	Example: create a port and bind receivers on it in one go.
		360
		361	my $port = rcv port,
		362	msg1 => sub { ...; 0 },
		363	msg2 => sub { ...; 0 },
		364	;
		365
		366	Example: create a port, bind receivers and send it in a message elsewhere
		367	in one go:
		368
		369	snd $otherport, reply =>
		370	rcv port,
		371	msg1 => sub { ...; 0 },
		372	...
143	}	373	;
144		374
145	# for indirect sends, use a different class	375	=cut
146	my $node = new AnyEvent::MP::Node::Direct $noderef;
147		376
148	$NODE{$_} = $node
149	for $noderef, split /,/, $noderef;
150
151	$node
152	}
153
154	sub snd($@) {	377	sub rcv($@) {
		378	my $port = shift;
155	my ($noderef, $port) = split /#/, shift, 2;	379	my ($noderef, $portid) = split /#/, $port, 2;
156		380
157	add_node $noderef	381	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
158	unless exists $NODE{$noderef};	382	or Carp::croak "$port: rcv can only be called on local ports, caught";
159		383
160	$NODE{$noderef}->send ([$port, [@_]]);	384	if (@_ == 1) {
161	}	385	my $cb = shift;
162		386	delete $PORT_DATA{$portid};
163	sub _inject {	387	$PORT{$portid} = sub {
164	my ($port, $msg) = @{+shift};	388	local $SELF = $port;
165		389	eval {
166	$port = $PORT{$port}
167	or return;
168
169	use Data::Dumper;
170	warn Dumper $msg;
171	}
172
173	sub normalise_noderef($) {
174	my ($noderef) = @_;
175
176	my $cv = AE::cv;
177	my @res;
178
179	$cv->begin (sub {
180	my %seen;
181	my @refs;
182	for (sort { $a->[0] <=> $b->[0] } @res) {
183	push @refs, $_->[1] unless $seen{$_->[1]}++
184	}
185	shift->send (join ",", @refs);
186	});
187
188	$noderef = $DEFAULT_PORT unless length $noderef;
189
190	my $idx;
191	for my $t (split /,/, $noderef) {
192	my $pri = ++$idx;
193
194	#TODO: this should be outside normalise_noderef and in become_public
195	if ($t =~ /^\d*$/) {
196	my $nodename = (POSIX::uname)[1];
197
198	$cv->begin;
199	AnyEvent::Socket::resolve_sockaddr $nodename, $t \|\| "aemp=$DEFAULT_PORT", "tcp", 0, undef, sub {
200	for (@_) {
201	my ($service, $host) = AnyEvent::Socket::unpack_sockaddr $_->[3];
202	push @res, [
203	$pri += 1e-5,
204	AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $host, $service
205	];
206	}	390	&$cb
207	$cv->end;	391	and kil $port;
208	};	392	};
209		393	_self_die if $@;
210	# my (undef, undef, undef, undef, @ipv4) = gethostbyname $nodename;	394	};
211	#
212	# for (@ipv4) {
213	# push @res, [
214	# $pri,
215	# AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $_, $t \|\| $DEFAULT_PORT,
216	# ];
217	# }
218	} else {	395	} else {
219	my ($host, $port) = AnyEvent::Socket::parse_hostport $t, "aemp=$DEFAULT_PORT"	396	my $self = $PORT_DATA{$portid} \|\|= do {
220	or Carp::croak "$t: unparsable transport descriptor";	397	my $self = bless {
		398	id => $port,
		399	}, "AnyEvent::MP::Port";
221		400
222	$cv->begin;	401	$PORT{$portid} = sub {
223	AnyEvent::Socket::resolve_sockaddr $host, $port, "tcp", 0, undef, sub {	402	local $SELF = $port;
224	for (@_) {	403
225	my ($service, $host) = AnyEvent::Socket::unpack_sockaddr $_->[3];	404	eval {
226	push @res, [	405	for (@{ $self->{rc0}{$_[0]} }) {
227	$pri += 1e-5,	406	$_ && &{$_->[0]}
228	AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $host, $service	407	&& undef $_;
229	];	408	}
		409
		410	for (@{ $self->{rcv}{$_[0]} }) {
		411	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
		412	&& &{$_->[0]}
		413	&& undef $_;
		414	}
		415
		416	for (@{ $self->{any} }) {
		417	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
		418	&& &{$_->[0]}
		419	&& undef $_;
		420	}
230	}	421	};
231	$cv->end;	422	_self_die if $@;
		423	};
		424
		425	$self
		426	};
		427
		428	"AnyEvent::MP::Port" eq ref $self
		429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		430
		431	while (@_) {
		432	my ($match, $cb) = splice @_, 0, 2;
		433
		434	if (!ref $match) {
		435	push @{ $self->{rc0}{$match} }, [$cb];
		436	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
		437	my ($type, @match) = @$match;
		438	@match
		439	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
		440	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
		441	} else {
		442	push @{ $self->{any} }, [$cb, $match];
232	}	443	}
233	}	444	}
234	}	445	}
235		446
236	$cv->end;	447	$port
237
238	$cv
239	}	448	}
240		449
241	sub become_public {	450	=item $closure = psub { BLOCK }
242	return if $PUBLIC;
243		451
244	my $noderef = join ",", ref $_[0] ? @{+shift} : shift;	452	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
245	my @args = @_;	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.
246		455
247	$NODE = (normalise_noderef $noderef)->recv;	456	This is useful when you register callbacks from C<rcv> callbacks:
248		457
249	my $self = new AnyEvent::MP::Node::Self noderef => $NODE;	458	rcv delayed_reply => sub {
250		459	my ($delay, @reply) = @_;
251	$NODE{""} = $self; # empty string == local node	460	my $timer = AE::timer $delay, 0, psub {
252		461	snd @reply, $SELF;
253	for my $t (split /,/, $NODE) {
254	$NODE{$t} = $self;
255
256	my ($host, $port) = AnyEvent::Socket::parse_hostport $t;
257
258	$LISTENER{$t} = AnyEvent::MP::Transport::mp_server $host, $port,
259	@args,
260	on_error => sub {
261	die "on_error<@_>\n";#d#
262	},
263	on_connect => sub {
264	my ($tp) = @_;
265
266	$NODE{$tp->{remote_id}} = $_[0];
267	},
268	sub {
269	my ($tp) = @_;
270
271	$NODE{"$tp->{peerhost}:$tp->{peerport}"} = $tp;
272	},
273	;	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	}
274	}	485	}
275
276	$PUBLIC = 1;
277	}	486	}
		487
		488	=item $guard = mon $port, $cb->(@reason)
		489
		490	=item $guard = mon $port, $rcvport
		491
		492	=item $guard = mon $port
		493
		494	=item $guard = mon $port, $rcvport, @msg
		495
		496	Monitor the given port and do something when the port is killed, and
		497	optionally return a guard that can be used to stop monitoring again.
		498
		499	In the first form (callback), the callback is simply called with any
		500	number of C<@reason> elements (no @reason means that the port was deleted
		501	"normally"). Note also that I<< the callback B<must> never die >>, so use
		502	C<eval> if unsure.
		503
		504	In the second form (another port given), the other port (C<$rcvport)
		505	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		506	"normal" kils nothing happens, while under all other conditions, the other
		507	port is killed with the same reason.
		508
		509	The third form (kill self) is the same as the second form, except that
		510	C<$rvport> defaults to C<$SELF>.
		511
		512	In the last form (message), a message of the form C<@msg, @reason> will be
		513	C<snd>.
		514
		515	As a rule of thumb, monitoring requests should always monitor a port from
		516	a local port (or callback). The reason is that kill messages might get
		517	lost, just like any other message. Another less obvious reason is that
		518	even monitoring requests can get lost (for exmaple, when the connection
		519	to the other node goes down permanently). When monitoring a port locally
		520	these problems do not exist.
		521
		522	Example: call a given callback when C<$port> is killed.
		523
		524	mon $port, sub { warn "port died because of <@_>\n" };
		525
		526	Example: kill ourselves when C<$port> is killed abnormally.
		527
		528	mon $port;
		529
		530	Example: send us a restart message when another C<$port> is killed.
		531
		532	mon $port, $self => "restart";
		533
		534	=cut
		535
		536	sub mon {
		537	my ($noderef, $port) = split /#/, shift, 2;
		538
		539	my $node = $NODE{$noderef} \|\| add_node $noderef;
		540
		541	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		542
		543	unless (ref $cb) {
		544	if (@_) {
		545	# send a kill info message
		546	my (@msg) = @_;
		547	$cb = sub { snd @msg, @_ };
		548	} else {
		549	# simply kill other port
		550	my $port = $cb;
		551	$cb = sub { kil $port, @_ if @_ };
		552	}
		553	}
		554
		555	$node->monitor ($port, $cb);
		556
		557	defined wantarray
		558	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		559	}
		560
		561	=item $guard = mon_guard $port, $ref, $ref...
		562
		563	Monitors the given C<$port> and keeps the passed references. When the port
		564	is killed, the references will be freed.
		565
		566	Optionally returns a guard that will stop the monitoring.
		567
		568	This function is useful when you create e.g. timers or other watchers and
		569	want to free them when the port gets killed:
		570
		571	$port->rcv (start => sub {
		572	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		573	undef $timer if 0.9 < rand;
		574	});
		575	});
		576
		577	=cut
		578
		579	sub mon_guard {
		580	my ($port, @refs) = @_;
		581
		582	#TODO: mon-less form?
		583
		584	mon $port, sub { 0 && @refs }
		585	}
		586
		587	=item kil $port[, @reason]
		588
		589	Kill the specified port with the given C<@reason>.
		590
		591	If no C<@reason> is specified, then the port is killed "normally" (linked
		592	ports will not be kileld, or even notified).
		593
		594	Otherwise, linked ports get killed with the same reason (second form of
		595	C<mon>, see below).
		596
		597	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		598	will be reported as reason C<< die => $@ >>.
		599
		600	Transport/communication errors are reported as C<< transport_error =>
		601	$message >>.
		602
		603	=back
		604
		605	=head1 NODE MESSAGES
		606
		607	Nodes understand the following messages sent to them. Many of them take
		608	arguments called C<@reply>, which will simply be used to compose a reply
		609	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
		610	the remaining arguments are simply the message data.
		611
		612	While other messages exist, they are not public and subject to change.
		613
		614	=over 4
		615
		616	=cut
		617
		618	=item lookup => $name, @reply
		619
		620	Replies with the port ID of the specified well-known port, or C<undef>.
		621
		622	=item devnull => ...
		623
		624	Generic data sink/CPU heat conversion.
		625
		626	=item relay => $port, @msg
		627
		628	Simply forwards the message to the given port.
		629
		630	=item eval => $string[ @reply]
		631
		632	Evaluates the given string. If C<@reply> is given, then a message of the
		633	form C<@reply, $@, @evalres> is sent.
		634
		635	Example: crash another node.
		636
		637	snd $othernode, eval => "exit";
		638
		639	=item time => @reply
		640
		641	Replies the the current node time to C<@reply>.
		642
		643	Example: tell the current node to send the current time to C<$myport> in a
		644	C<timereply> message.
		645
		646	snd $NODE, time => $myport, timereply => 1, 2;
		647	# => snd $myport, timereply => 1, 2, <time>
		648
		649	=back
		650
		651	=head1 AnyEvent::MP vs. Distributed Erlang
		652
		653	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		654	== aemp node, Erlang process == aemp port), so many of the documents and
		655	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		656	sample:
		657
		658	http://www.Erlang.se/doc/programming_rules.shtml
		659	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		660	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		661	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		662
		663	Despite the similarities, there are also some important differences:
		664
		665	=over 4
		666
		667	=item * Node references contain the recipe on how to contact them.
		668
		669	Erlang relies on special naming and DNS to work everywhere in the
		670	same way. AEMP relies on each node knowing it's own address(es), with
		671	convenience functionality.
		672
		673	This means that AEMP requires a less tightly controlled environment at the
		674	cost of longer node references and a slightly higher management overhead.
		675
		676	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		677
		678	Erlang uses processes that selctively receive messages, and therefore
		679	needs a queue. AEMP is event based, queuing messages would serve no useful
		680	purpose.
		681
		682	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		683
		684	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		685
		686	Sending messages in Erlang is synchronous and blocks the process. AEMP
		687	sends are immediate, connection establishment is handled in the
		688	background.
		689
		690	=item * Erlang can silently lose messages, AEMP cannot.
		691
		692	Erlang makes few guarantees on messages delivery - messages can get lost
		693	without any of the processes realising it (i.e. you send messages a, b,
		694	and c, and the other side only receives messages a and c).
		695
		696	AEMP guarantees correct ordering, and the guarantee that there are no
		697	holes in the message sequence.
		698
		699	=item * In Erlang, processes can be declared dead and later be found to be
		700	alive.
		701
		702	In Erlang it can happen that a monitored process is declared dead and
		703	linked processes get killed, but later it turns out that the process is
		704	still alive - and can receive messages.
		705
		706	In AEMP, when port monitoring detects a port as dead, then that port will
		707	eventually be killed - it cannot happen that a node detects a port as dead
		708	and then later sends messages to it, finding it is still alive.
		709
		710	=item * Erlang can send messages to the wrong port, AEMP does not.
		711
		712	In Erlang it is quite possible that a node that restarts reuses a process
		713	ID known to other nodes for a completely different process, causing
		714	messages destined for that process to end up in an unrelated process.
		715
		716	AEMP never reuses port IDs, so old messages or old port IDs floating
		717	around in the network will not be sent to an unrelated port.
		718
		719	=item * Erlang uses unprotected connections, AEMP uses secure
		720	authentication and can use TLS.
		721
		722	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		723	securely authenticate nodes.
		724
		725	=item * The AEMP protocol is optimised for both text-based and binary
		726	communications.
		727
		728	The AEMP protocol, unlike the Erlang protocol, supports both
		729	language-independent text-only protocols (good for debugging) and binary,
		730	language-specific serialisers (e.g. Storable).
		731
		732	It has also been carefully designed to be implementable in other languages
		733	with a minimum of work while gracefully degrading fucntionality to make the
		734	protocol simple.
		735
		736	=item * AEMP has more flexible monitoring options than Erlang.
		737
		738	In Erlang, you can chose to receive I<all> exit signals as messages
		739	or I<none>, there is no in-between, so monitoring single processes is
		740	difficult to implement. Monitoring in AEMP is more flexible than in
		741	Erlang, as one can choose between automatic kill, exit message or callback
		742	on a per-process basis.
		743
		744	=item * Erlang tries to hide remote/local connections, AEMP does not.
		745
		746	Monitoring in Erlang is not an indicator of process death/crashes,
		747	as linking is (except linking is unreliable in Erlang).
		748
		749	In AEMP, you don't "look up" registered port names or send to named ports
		750	that might or might not be persistent. Instead, you normally spawn a port
		751	on the remote node. The init function monitors the you, and you monitor
		752	the remote port. Since both monitors are local to the node, they are much
		753	more reliable.
		754
		755	This also saves round-trips and avoids sending messages to the wrong port
		756	(hard to do in Erlang).
278		757
279	=back	758	=back
280		759
281	=head1 SEE ALSO	760	=head1 SEE ALSO
282		761

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.2 by root, Fri Jul 31 20:55:46 2009 UTC vs. Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC

Diff Legend

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.2 by root, Fri Jul 31 20:55:46 2009 UTC vs.
Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC