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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.4 by root, Sat Aug 1 07:36:30 2009 UTC vs.
Revision 1.57 by root, Sat Aug 15 04:34:34 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	# initialise the node so it can send/receive messages
		16	initialise_node; # -OR-
		17	initialise_node "localhost:4040"; # -OR-
		18	initialise_node "slave/", "localhost:4040"
		19
		20	# ports are message endpoints
		21
		22	# sending messages
12	snd $port, type => data...;	23	snd $port, type => data...;
		24	snd $port, @msg;
		25	snd @msg_with_first_element_being_a_port;
13		26
14	rcv $port, smartmatch => $cb->($port, @msg);	27	# creating/using ports, the simple way
		28	my $simple_port = port { my @msg = @_; 0 };
15		29
16	# examples:	30	# creating/using ports, tagged message matching
		31	my $port = port;
17	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
18	rcv $port1, pong => sub { warn "pong received\n" };	33	rcv $port, pong => sub { warn "pong received\n"; 0 };
19	snd $port2, ping => $port1;
20		34
21	# more, smarter, matches (_any_ is exported by this module)	35	# create a port on another node
22	rcv $port, [child_died => $pid] => sub { ...	36	my $port = spawn $node, $initfunc, @initdata;
23	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	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		46	AnyEvent::MP::Intro - outdated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.
24		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
		62	At the moment, this module family is severly broken and underdocumented,
		63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
		64	stay tuned!
		65
32	=head1 CONCEPTS	66	=head1 CONCEPTS
33		67
34	=over 4	68	=over 4
35		69
36	=item port	70	=item port
37		71
38	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).
39	you can register C<rcv> handlers with. All C<rcv> handlers will receive	73
		74	Ports allow you to register C<rcv> handlers that can match all or just
40	messages they match, messages will not be queued.	75	some messages. Messages will not be queued.
41		76
42	=item port id - C<noderef#portname>	77	=item port id - C<noderef#portname>
43		78
44	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	79	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
45	by a port name (a printable string of unspecified format).	80	separator, and a port name (a printable string of unspecified format). An
		81	exception is the the node port, whose ID is identical to its node
		82	reference.
46		83
47	=item node	84	=item node
48		85
49	A node is a single process containing at least one port - the node	86	A node is a single process containing at least one port - the node port,
50	port. You can send messages to node ports to let them create new ports,	87	which provides nodes to manage each other remotely, and to create new
51	among other things.	88	ports.
52		89
53	Initially, nodes are either private (single-process only) or hidden	90	Nodes are either private (single-process only), slaves (connected to a
54	(connected to a master node only). Only when they epxlicitly "become	91	master node only) or public nodes (connectable from unrelated nodes).
55	public" can you send them messages from unrelated other nodes.
56		92
57	=item noderef - C<host:port,host:port...>, C<id@noderef, C<id>	93	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
58		94
59	A noderef is a string that either uniquely identifies a given node (for	95	A node reference is a string that either simply identifies the node (for
60	private and hidden nodes), or contains a recipe on how to reach a given	96	private and slave nodes), or contains a recipe on how to reach a given
61	node (for public nodes).	97	node (for public nodes).
62		98
		99	This recipe is simply a comma-separated list of C<address:port> pairs (for
		100	TCP/IP, other protocols might look different).
		101
		102	Node references come in two flavours: resolved (containing only numerical
		103	addresses) or unresolved (where hostnames are used instead of addresses).
		104
		105	Before using an unresolved node reference in a message you first have to
		106	resolve it.
		107
63	=back	108	=back
64		109
65	=head1 VARIABLES/FUNCTIONS	110	=head1 VARIABLES/FUNCTIONS
66		111
67	=over 4	112	=over 4
68		113
69	=cut	114	=cut
70		115
71	package AnyEvent::MP;	116	package AnyEvent::MP;
72		117
73	use AnyEvent::MP::Util ();
74	use AnyEvent::MP::Node;	118	use AnyEvent::MP::Kernel;
75	use AnyEvent::MP::Transport;
76		119
77	use utf8;
78	use common::sense;	120	use common::sense;
79		121
80	use Carp ();	122	use Carp ();
81		123
82	use AE ();	124	use AE ();
83		125
84	use base "Exporter";	126	use base "Exporter";
85		127
86	our $VERSION = '0.0';	128	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
87	our @EXPORT = qw(NODE $NODE $PORT snd rcv _any_);
88		129
89	our $DEFAULT_SECRET;	130	our @EXPORT = qw(
90	our $DEFAULT_PORT = "4040";	131	NODE $NODE *SELF node_of _any_
		132	resolve_node initialise_node
		133	snd rcv mon kil reg psub spawn
		134	port
		135	);
91		136
92	our $CONNECT_INTERVAL = 5; # new connect every 5s, at least	137	our $SELF;
93	our $CONNECT_TIMEOUT = 30; # includes handshake
94		138
95	sub default_secret {	139	sub _self_die() {
96	unless (defined $DEFAULT_SECRET) {	140	my $msg = $@;
97	if (open my $fh, "<$ENV{HOME}/.aemp-secret") {	141	$msg =~ s/\n+$// unless ref $msg;
98	sysread $fh, $DEFAULT_SECRET, -s $fh;	142	kil $SELF, die => $msg;
99	} else {
100	$DEFAULT_SECRET = AnyEvent::MP::Util::nonce 32;
101	}
102	}
103
104	$DEFAULT_SECRET
105	}	143	}
106		144
107	=item NODE / $NODE	145	=item $thisnode = NODE / $NODE
108		146
109	The C<NODE ()> function and the C<$NODE> variable contain the noderef of	147	The C<NODE> function returns, and the C<$NODE> variable contains the
110	the local node. The value is initialised by a call to C<become_public> or	148	noderef of the local node. The value is initialised by a call to
111	C<become_slave>, after which all local port identifiers become invalid.	149	C<initialise_node>.
112		150
113	=cut	151	=item $noderef = node_of $port
114		152
115	our $UNIQ = sprintf "%x.%x", $$, time; # per-process/node unique cookie	153	Extracts and returns the noderef from a port ID or a noderef.
116	our $PUBLIC = 0;
117	our $NODE;
118	our $PORT;
119		154
120	our %NODE; # node id to transport mapping, or "undef", for local node	155	=item initialise_node $noderef, $seednode, $seednode...
121	our %PORT; # local ports
122	our %LISTENER; # local transports
123		156
124	sub NODE() { $NODE }	157	=item initialise_node "slave/", $master, $master...
125		158
126	{	159	Before a node can talk to other nodes on the network it has to initialise
127	use POSIX ();	160	itself - the minimum a node needs to know is it's own name, and optionally
128	my $nodename = (POSIX::uname)[1];	161	it should know the noderefs of some other nodes in the network.
129	$NODE = "$$\@$nodename";
130	}
131		162
132	sub _ANY_() { 1 }	163	This function initialises a node - it must be called exactly once (or
133	sub _any_() { \&_ANY_ }	164	never) before calling other AnyEvent::MP functions.
134		165
135	sub add_node {	166	All arguments (optionally except for the first) are noderefs, which can be
136	my ($noderef) = @_;	167	either resolved or unresolved.
137		168
138	return $NODE{$noderef}	169	The first argument will be looked up in the configuration database first
139	if exists $NODE{$noderef};	170	(if it is C<undef> then the current nodename will be used instead) to find
		171	the relevant configuration profile (see L<aemp>). If none is found then
		172	the default configuration is used. The configuration supplies additional
		173	seed/master nodes and can override the actual noderef.
140		174
141	for (split /,/, $noderef) {	175	There are two types of networked nodes, public nodes and slave nodes:
142	return $NODE{$noderef} = $NODE{$_}
143	if exists $NODE{$_};
144	}
145		176
146	# for indirect sends, use a different class	177	=over 4
147	my $node = new AnyEvent::MP::Node::Direct $noderef;
148		178
149	$NODE{$_} = $node	179	=item public nodes
150	for $noderef, split /,/, $noderef;
151		180
152	$node	181	For public nodes, C<$noderef> (supplied either directly to
153	}	182	C<initialise_node> or indirectly via a profile or the nodename) must be a
		183	noderef (possibly unresolved, in which case it will be resolved).
154		184
		185	After resolving, the node will bind itself on all endpoints and try to
		186	connect to all additional C<$seednodes> that are specified. Seednodes are
		187	optional and can be used to quickly bootstrap the node into an existing
		188	network.
		189
		190	=item slave nodes
		191
		192	When the C<$noderef> (either as given or overriden by the config file)
		193	is the special string C<slave/>, then the node will become a slave
		194	node. Slave nodes cannot be contacted from outside and will route most of
		195	their traffic to the master node that they attach to.
		196
		197	At least one additional noderef is required (either by specifying it
		198	directly or because it is part of the configuration profile): The node
		199	will try to connect to all of them and will become a slave attached to the
		200	first node it can successfully connect to.
		201
		202	Note that slave nodes cannot change their name, and consequently, their
		203	master, so if the master goes down, the slave node will not function well
		204	anymore until it can re-establish conenciton to its master. This makes
		205	slave nodes unsuitable for long-term nodes or fault-tolerant networks.
		206
		207	=back
		208
		209	This function will block until all nodes have been resolved and, for slave
		210	nodes, until it has successfully established a connection to a master
		211	server.
		212
		213	All the seednodes will also be specially marked to automatically retry
		214	connecting to them infinitely.
		215
		216	Example: become a public node listening on the guessed noderef, or the one
		217	specified via C<aemp> for the current node. This should be the most common
		218	form of invocation for "daemon"-type nodes.
		219
		220	initialise_node;
		221
		222	Example: become a slave node to any of the the seednodes specified via
		223	C<aemp>. This form is often used for commandline clients.
		224
		225	initialise_node "slave/";
		226
		227	Example: become a slave node to any of the specified master servers. This
		228	form is also often used for commandline clients.
		229
		230	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		231
		232	Example: become a public node, and try to contact some well-known master
		233	servers to become part of the network.
		234
		235	initialise_node undef, "master1", "master2";
		236
		237	Example: become a public node listening on port C<4041>.
		238
		239	initialise_node 4041;
		240
		241	Example: become a public node, only visible on localhost port 4044.
		242
		243	initialise_node "localhost:4044";
		244
		245	=item $cv = resolve_node $noderef
		246
		247	Takes an unresolved node reference that may contain hostnames and
		248	abbreviated IDs, resolves all of them and returns a resolved node
		249	reference.
		250
		251	In addition to C<address:port> pairs allowed in resolved noderefs, the
		252	following forms are supported:
		253
		254	=over 4
		255
		256	=item the empty string
		257
		258	An empty-string component gets resolved as if the default port (4040) was
		259	specified.
		260
		261	=item naked port numbers (e.g. C<1234>)
		262
		263	These are resolved by prepending the local nodename and a colon, to be
		264	further resolved.
		265
		266	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		267
		268	These are resolved by using AnyEvent::DNS to resolve them, optionally
		269	looking up SRV records for the C<aemp=4040> port, if no port was
		270	specified.
		271
		272	=back
		273
		274	=item $SELF
		275
		276	Contains the current port id while executing C<rcv> callbacks or C<psub>
		277	blocks.
		278
		279	=item SELF, %SELF, @SELF...
		280
		281	Due to some quirks in how perl exports variables, it is impossible to
		282	just export C<$SELF>, all the symbols called C<SELF> are exported by this
		283	module, but only C<$SELF> is currently used.
		284
155	=item snd $portid, type => @data	285	=item snd $port, type => @data
156		286
157	=item snd $portid, @msg	287	=item snd $port, @msg
158		288
159	Send the given message to the given port ID, which can identify either a	289	Send the given message to the given port ID, which can identify either
160	local or a remote port.	290	a local or a remote port, and must be a port ID.
161		291
162	While the message can be about anything, it is highly recommended to use	292	While the message can be about anything, it is highly recommended to use a
163	a constant string as first element.	293	string as first element (a port ID, or some word that indicates a request
		294	type etc.).
164		295
165	The message data effectively becomes read-only after a call to this	296	The message data effectively becomes read-only after a call to this
166	function: modifying any argument is not allowed and can cause many	297	function: modifying any argument is not allowed and can cause many
167	problems.	298	problems.
168		299
…		…
170	JSON is used, then only strings, numbers and arrays and hashes consisting	301	JSON is used, then only strings, numbers and arrays and hashes consisting
171	of those are allowed (no objects). When Storable is used, then anything	302	of those are allowed (no objects). When Storable is used, then anything
172	that Storable can serialise and deserialise is allowed, and for the local	303	that Storable can serialise and deserialise is allowed, and for the local
173	node, anything can be passed.	304	node, anything can be passed.
174		305
		306	=item $local_port = port
		307
		308	Create a new local port object and returns its port ID. Initially it has
		309	no callbacks set and will throw an error when it receives messages.
		310
		311	=item $local_port = port { my @msg = @_ }
		312
		313	Creates a new local port, and returns its ID. Semantically the same as
		314	creating a port and calling C<rcv $port, $callback> on it.
		315
		316	The block will be called for every message received on the port, with the
		317	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		318	port to be C<kil>ed. The message will be passed as-is, no extra argument
		319	(i.e. no port ID) will be passed to the callback.
		320
		321	If you want to stop/destroy the port, simply C<kil> it:
		322
		323	my $port = port {
		324	my @msg = @_;
		325	...
		326	kil $SELF;
		327	};
		328
175	=cut	329	=cut
176		330
177	sub snd(@) {	331	sub rcv($@);
178	my ($noderef, $port) = split /#/, shift, 2;
179		332
180	add_node $noderef	333	sub _kilme {
181	unless exists $NODE{$noderef};	334	die "received message on port without callback";
182
183	$NODE{$noderef}->send (["$port", [@_]]);
184	}	335	}
185		336
		337	sub port(;&) {
		338	my $id = "$UNIQ." . $ID++;
		339	my $port = "$NODE#$id";
		340
		341	rcv $port, shift \|\| \&_kilme;
		342
		343	$port
		344	}
		345
186	=item rcv $portid, type => $callback->(@msg)	346	=item rcv $local_port, $callback->(@msg)
187		347
188	=item rcv $portid, $smartmatch => $callback->(@msg)	348	Replaces the default callback on the specified port. There is no way to
		349	remove the default callback: use C<sub { }> to disable it, or better
		350	C<kil> the port when it is no longer needed.
189		351
190	=item rcv $portid, [$smartmatch...] => $callback->(@msg)	352	The global C<$SELF> (exported by this module) contains C<$port> while
		353	executing the callback. Runtime errors during callback execution will
		354	result in the port being C<kil>ed.
191		355
192	Register a callback on the port identified by C<$portid>, which I<must> be	356	The default callback received all messages not matched by a more specific
193	a local port.	357	C<tag> match.
194		358
195	The callback has to return a true value when its work is done, after	359	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
196	which is will be removed, or a false value in which case it will stay
197	registered.
198		360
199	If the match is an array reference, then it will be matched against the	361	Register (or replace) callbacks to be called on messages starting with the
200	first elements of the message, otherwise only the first element is being	362	given tag on the given port (and return the port), or unregister it (when
201	matched.	363	C<$callback> is C<$undef> or missing). There can only be one callback
		364	registered for each tag.
202		365
203	Any element in the match that is specified as C<_any_> (a function	366	The original message will be passed to the callback, after the first
204	exported by this module) matches any single element of the message.	367	element (the tag) has been removed. The callback will use the same
		368	environment as the default callback (see above).
205		369
206	While not required, it is highly recommended that the first matching	370	Example: create a port and bind receivers on it in one go.
207	element is a string identifying the message. The one-string-only match is	371
208	also the most efficient match (by far).	372	my $port = rcv port,
		373	msg1 => sub { ... },
		374	msg2 => sub { ... },
		375	;
		376
		377	Example: create a port, bind receivers and send it in a message elsewhere
		378	in one go:
		379
		380	snd $otherport, reply =>
		381	rcv port,
		382	msg1 => sub { ... },
		383	...
		384	;
		385
		386	Example: temporarily register a rcv callback for a tag matching some port
		387	(e.g. for a rpc reply) and unregister it after a message was received.
		388
		389	rcv $port, $otherport => sub {
		390	my @reply = @_;
		391
		392	rcv $SELF, $otherport;
		393	};
209		394
210	=cut	395	=cut
211		396
212	sub rcv($@) {	397	sub rcv($@) {
213	my ($port, $match, $cb) = @_;	398	my $port = shift;
214
215	my $port = $PORT{$port}
216	or do {
217	my ($noderef, $lport) = split /#/, $port;	399	my ($noderef, $portid) = split /#/, $port, 2;
218	"AnyEvent::MP::Node::Self" eq ref $NODE{$noderef}	400
		401	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
219	or Carp::croak "$port: can only rcv on local ports";	402	or Carp::croak "$port: rcv can only be called on local ports, caught";
220		403
221	$PORT{$lport}	404	while (@_) {
222	or Carp::croak "$port: port does not exist";	405	if (ref $_[0]) {
223		406	if (my $self = $PORT_DATA{$portid}) {
224	$PORT{$port} = $PORT{$lport} # also return	407	"AnyEvent::MP::Port" eq ref $self
225	};	408	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
226		409
227	if (!ref $match) {	410	$self->[2] = shift;
228	push @{ $port->{rc0}{$match} }, [$cb];
229	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
230	my ($type, @match) = @$match;
231	@match
232	? push @{ $port->{rcv}{$match->[0]} }, [$cb, \@match]
233	: push @{ $port->{rc0}{$match->[0]} }, [$cb];
234	} else {	411	} else {
235	push @{ $port->{any} }, [$cb, $match];	412	my $cb = shift;
236	}	413	$PORT{$portid} = sub {
237	}	414	local $SELF = $port;
238		415	eval { &$cb }; _self_die if $@;
239	sub _inject {
240	my ($port, $msg) = @{+shift};
241
242	$port = $PORT{$port}
243	or return;
244
245	@_ = @$msg;
246
247	for (@{ $port->{rc0}{$msg->[0]} }) {
248	$_ && &{$_->[0]}
249	&& undef $_;
250	}
251
252	for (@{ $port->{rcv}{$msg->[0]} }) {
253	$_ && [@_[1..$#{$_->[1]}]] ~~ $_->[1]
254	&& &{$_->[0]}
255	&& undef $_;
256	}
257
258	for (@{ $port->{any} }) {
259	$_ && [@_[0..$#{$_->[1]}]] ~~ $_->[1]
260	&& &{$_->[0]}
261	&& undef $_;
262	}
263	}
264
265	sub normalise_noderef($) {
266	my ($noderef) = @_;
267
268	my $cv = AE::cv;
269	my @res;
270
271	$cv->begin (sub {
272	my %seen;
273	my @refs;
274	for (sort { $a->[0] <=> $b->[0] } @res) {
275	push @refs, $_->[1] unless $seen{$_->[1]}++
276	}
277	shift->send (join ",", @refs);
278	});
279
280	$noderef = $DEFAULT_PORT unless length $noderef;
281
282	my $idx;
283	for my $t (split /,/, $noderef) {
284	my $pri = ++$idx;
285
286	#TODO: this should be outside normalise_noderef and in become_public
287	if ($t =~ /^\d*$/) {
288	my $nodename = (POSIX::uname)[1];
289
290	$cv->begin;
291	AnyEvent::Socket::resolve_sockaddr $nodename, $t \|\| "aemp=$DEFAULT_PORT", "tcp", 0, undef, sub {
292	for (@_) {
293	my ($service, $host) = AnyEvent::Socket::unpack_sockaddr $_->[3];
294	push @res, [
295	$pri += 1e-5,
296	AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $host, $service
297	];
298	}	416	};
299	$cv->end;	417	}
		418	} elsif (defined $_[0]) {
		419	my $self = $PORT_DATA{$portid} \|\|= do {
		420	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		421
		422	$PORT{$portid} = sub {
		423	local $SELF = $port;
		424
		425	if (my $cb = $self->[1]{$_[0]}) {
		426	shift;
		427	eval { &$cb }; _self_die if $@;
		428	} else {
		429	&{ $self->[0] };
		430	}
		431	};
		432
		433	$self
300	};	434	};
301		435
302	# my (undef, undef, undef, undef, @ipv4) = gethostbyname $nodename;	436	"AnyEvent::MP::Port" eq ref $self
303	#	437	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
304	# for (@ipv4) {	438
305	# push @res, [	439	my ($tag, $cb) = splice @_, 0, 2;
306	# $pri,	440
307	# AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $_, $t \|\| $DEFAULT_PORT,	441	if (defined $cb) {
308	# ];	442	$self->[1]{$tag} = $cb;
309	# }
310	} else {	443	} else {
311	my ($host, $port) = AnyEvent::Socket::parse_hostport $t, "aemp=$DEFAULT_PORT"	444	delete $self->[1]{$tag};
312	or Carp::croak "$t: unparsable transport descriptor";
313
314	$cv->begin;
315	AnyEvent::Socket::resolve_sockaddr $host, $port, "tcp", 0, undef, sub {
316	for (@_) {
317	my ($service, $host) = AnyEvent::Socket::unpack_sockaddr $_->[3];
318	push @res, [
319	$pri += 1e-5,
320	AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $host, $service
321	];
322	}
323	$cv->end;
324	}	445	}
325	}	446	}
326	}	447	}
327		448
328	$cv->end;	449	$port
329
330	$cv
331	}	450	}
332		451
333	sub become_public {	452	=item $closure = psub { BLOCK }
334	return if $PUBLIC;
335		453
336	my $noderef = join ",", ref $_[0] ? @{+shift} : shift;	454	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
337	my @args = @_;	455	closure is executed, sets up the environment in the same way as in C<rcv>
		456	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
338		457
339	$NODE = (normalise_noderef $noderef)->recv;	458	This is useful when you register callbacks from C<rcv> callbacks:
340		459
341	for my $t (split /,/, $NODE) {	460	rcv delayed_reply => sub {
342	$NODE{$t} = $NODE{""};	461	my ($delay, @reply) = @_;
343		462	my $timer = AE::timer $delay, 0, psub {
344	my ($host, $port) = AnyEvent::Socket::parse_hostport $t;	463	snd @reply, $SELF;
345
346	$LISTENER{$t} = AnyEvent::MP::Transport::mp_server $host, $port,
347	@args,
348	on_error => sub {
349	die "on_error<@_>\n";#d#
350	},
351	on_connect => sub {
352	my ($tp) = @_;
353
354	$NODE{$tp->{remote_id}} = $_[0];
355	},
356	sub {
357	my ($tp) = @_;
358
359	$NODE{"$tp->{peerhost}:$tp->{peerport}"} = $tp;
360	},
361	;	464	};
		465	};
		466
		467	=cut
		468
		469	sub psub(&) {
		470	my $cb = shift;
		471
		472	my $port = $SELF
		473	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		474
		475	sub {
		476	local $SELF = $port;
		477
		478	if (wantarray) {
		479	my @res = eval { &$cb };
		480	_self_die if $@;
		481	@res
		482	} else {
		483	my $res = eval { &$cb };
		484	_self_die if $@;
		485	$res
		486	}
362	}	487	}
363
364	$PUBLIC = 1;
365	}	488	}
366		489
		490	=item $guard = mon $port, $cb->(@reason)
		491
		492	=item $guard = mon $port, $rcvport
		493
		494	=item $guard = mon $port
		495
		496	=item $guard = mon $port, $rcvport, @msg
		497
		498	Monitor the given port and do something when the port is killed or
		499	messages to it were lost, and optionally return a guard that can be used
		500	to stop monitoring again.
		501
		502	C<mon> effectively guarantees that, in the absence of hardware failures,
		503	that after starting the monitor, either all messages sent to the port
		504	will arrive, or the monitoring action will be invoked after possible
		505	message loss has been detected. No messages will be lost "in between"
		506	(after the first lost message no further messages will be received by the
		507	port). After the monitoring action was invoked, further messages might get
		508	delivered again.
		509
		510	In the first form (callback), the callback is simply called with any
		511	number of C<@reason> elements (no @reason means that the port was deleted
		512	"normally"). Note also that I<< the callback B<must> never die >>, so use
		513	C<eval> if unsure.
		514
		515	In the second form (another port given), the other port (C<$rcvport>)
		516	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		517	"normal" kils nothing happens, while under all other conditions, the other
		518	port is killed with the same reason.
		519
		520	The third form (kill self) is the same as the second form, except that
		521	C<$rvport> defaults to C<$SELF>.
		522
		523	In the last form (message), a message of the form C<@msg, @reason> will be
		524	C<snd>.
		525
		526	As a rule of thumb, monitoring requests should always monitor a port from
		527	a local port (or callback). The reason is that kill messages might get
		528	lost, just like any other message. Another less obvious reason is that
		529	even monitoring requests can get lost (for exmaple, when the connection
		530	to the other node goes down permanently). When monitoring a port locally
		531	these problems do not exist.
		532
		533	Example: call a given callback when C<$port> is killed.
		534
		535	mon $port, sub { warn "port died because of <@_>\n" };
		536
		537	Example: kill ourselves when C<$port> is killed abnormally.
		538
		539	mon $port;
		540
		541	Example: send us a restart message when another C<$port> is killed.
		542
		543	mon $port, $self => "restart";
		544
		545	=cut
		546
		547	sub mon {
		548	my ($noderef, $port) = split /#/, shift, 2;
		549
		550	my $node = $NODE{$noderef} \|\| add_node $noderef;
		551
		552	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		553
		554	unless (ref $cb) {
		555	if (@_) {
		556	# send a kill info message
		557	my (@msg) = ($cb, @_);
		558	$cb = sub { snd @msg, @_ };
		559	} else {
		560	# simply kill other port
		561	my $port = $cb;
		562	$cb = sub { kil $port, @_ if @_ };
		563	}
		564	}
		565
		566	$node->monitor ($port, $cb);
		567
		568	defined wantarray
		569	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		570	}
		571
		572	=item $guard = mon_guard $port, $ref, $ref...
		573
		574	Monitors the given C<$port> and keeps the passed references. When the port
		575	is killed, the references will be freed.
		576
		577	Optionally returns a guard that will stop the monitoring.
		578
		579	This function is useful when you create e.g. timers or other watchers and
		580	want to free them when the port gets killed:
		581
		582	$port->rcv (start => sub {
		583	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		584	undef $timer if 0.9 < rand;
		585	});
		586	});
		587
		588	=cut
		589
		590	sub mon_guard {
		591	my ($port, @refs) = @_;
		592
		593	#TODO: mon-less form?
		594
		595	mon $port, sub { 0 && @refs }
		596	}
		597
		598	=item kil $port[, @reason]
		599
		600	Kill the specified port with the given C<@reason>.
		601
		602	If no C<@reason> is specified, then the port is killed "normally" (linked
		603	ports will not be kileld, or even notified).
		604
		605	Otherwise, linked ports get killed with the same reason (second form of
		606	C<mon>, see below).
		607
		608	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		609	will be reported as reason C<< die => $@ >>.
		610
		611	Transport/communication errors are reported as C<< transport_error =>
		612	$message >>.
		613
		614	=cut
		615
		616	=item $port = spawn $node, $initfunc[, @initdata]
		617
		618	Creates a port on the node C<$node> (which can also be a port ID, in which
		619	case it's the node where that port resides).
		620
		621	The port ID of the newly created port is return immediately, and it is
		622	permissible to immediately start sending messages or monitor the port.
		623
		624	After the port has been created, the init function is
		625	called. This function must be a fully-qualified function name
		626	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		627	program, use C<::name>.
		628
		629	If the function doesn't exist, then the node tries to C<require>
		630	the package, then the package above the package and so on (e.g.
		631	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		632	exists or it runs out of package names.
		633
		634	The init function is then called with the newly-created port as context
		635	object (C<$SELF>) and the C<@initdata> values as arguments.
		636
		637	A common idiom is to pass your own port, monitor the spawned port, and
		638	in the init function, monitor the original port. This two-way monitoring
		639	ensures that both ports get cleaned up when there is a problem.
		640
		641	Example: spawn a chat server port on C<$othernode>.
		642
		643	# this node, executed from within a port context:
		644	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		645	mon $server;
		646
		647	# init function on C<$othernode>
		648	sub connect {
		649	my ($srcport) = @_;
		650
		651	mon $srcport;
		652
		653	rcv $SELF, sub {
		654	...
		655	};
		656	}
		657
		658	=cut
		659
		660	sub _spawn {
		661	my $port = shift;
		662	my $init = shift;
		663
		664	local $SELF = "$NODE#$port";
		665	eval {
		666	&{ load_func $init }
		667	};
		668	_self_die if $@;
		669	}
		670
		671	sub spawn(@) {
		672	my ($noderef, undef) = split /#/, shift, 2;
		673
		674	my $id = "$RUNIQ." . $ID++;
		675
		676	$_[0] =~ /::/
		677	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		678
		679	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		680
		681	"$noderef#$id"
		682	}
		683
367	=back	684	=back
368		685
369	=head1 NODE MESSAGES	686	=head1 AnyEvent::MP vs. Distributed Erlang
370		687
371	Nodes understand the following messages sent to them:	688	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		689	== aemp node, Erlang process == aemp port), so many of the documents and
		690	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		691	sample:
		692
		693	http://www.Erlang.se/doc/programming_rules.shtml
		694	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		695	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		696	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		697
		698	Despite the similarities, there are also some important differences:
372		699
373	=over 4	700	=over 4
374		701
375	=cut	702	=item * Node references contain the recipe on how to contact them.
376		703
377	#############################################################################	704	Erlang relies on special naming and DNS to work everywhere in the
378	# self node code	705	same way. AEMP relies on each node knowing it's own address(es), with
		706	convenience functionality.
379		707
380	sub _new_port($) {	708	This means that AEMP requires a less tightly controlled environment at the
381	my ($name) = @_;	709	cost of longer node references and a slightly higher management overhead.
382		710
383	my ($noderef, $portname) = split /#/, $name;	711	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		712	uses "local ports are like remote ports".
384		713
385	$PORT{$name} =	714	The failure modes for local ports are quite different (runtime errors
386	$PORT{$portname} = {	715	only) then for remote ports - when a local port dies, you I<know> it dies,
387	names => [$name, $portname],	716	when a connection to another node dies, you know nothing about the other
388	};	717	port.
389	}
390		718
391	$NODE{""} = new AnyEvent::MP::Node::Self noderef => $NODE;	719	Erlang pretends remote ports are as reliable as local ports, even when
392	_new_port "";	720	they are not.
393		721
394	=item relay => $port, @msg	722	AEMP encourages a "treat remote ports differently" philosophy, with local
		723	ports being the special case/exception, where transport errors cannot
		724	occur.
395		725
396	Simply forwards the message to the given port.	726	=item * Erlang uses processes and a mailbox, AEMP does not queue.
397		727
398	=cut	728	Erlang uses processes that selectively receive messages, and therefore
		729	needs a queue. AEMP is event based, queuing messages would serve no
		730	useful purpose. For the same reason the pattern-matching abilities of
		731	AnyEvent::MP are more limited, as there is little need to be able to
		732	filter messages without dequeing them.
399		733
400	rcv "", relay => \&snd;	734	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
401		735
402	=item eval => $string[ @reply]	736	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
403		737
404	Evaluates the given string. If C<@reply> is given, then a message of the	738	Sending messages in Erlang is synchronous and blocks the process (and
405	form C<@reply, $@, @evalres> is sent (C<$reply[0]> is the port to reply to).	739	so does not need a queue that can overflow). AEMP sends are immediate,
		740	connection establishment is handled in the background.
406		741
407	=cut	742	=item * Erlang suffers from silent message loss, AEMP does not.
408		743
409	rcv "", eval => sub {	744	Erlang makes few guarantees on messages delivery - messages can get lost
410	my (undef, $string, @reply) = @_;	745	without any of the processes realising it (i.e. you send messages a, b,
411	my @res = eval $string;	746	and c, and the other side only receives messages a and c).
412	snd @reply, "$@", @res if @reply;
413	};
414		747
415	=item time => @reply	748	AEMP guarantees correct ordering, and the guarantee that there are no
		749	holes in the message sequence.
416		750
417	Replies the the current node time to C<@reply>.	751	=item * In Erlang, processes can be declared dead and later be found to be
		752	alive.
418		753
419	=cut	754	In Erlang it can happen that a monitored process is declared dead and
		755	linked processes get killed, but later it turns out that the process is
		756	still alive - and can receive messages.
420		757
421	rcv "", time => sub { shift; snd @_, AE::time };	758	In AEMP, when port monitoring detects a port as dead, then that port will
		759	eventually be killed - it cannot happen that a node detects a port as dead
		760	and then later sends messages to it, finding it is still alive.
		761
		762	=item * Erlang can send messages to the wrong port, AEMP does not.
		763
		764	In Erlang it is quite likely that a node that restarts reuses a process ID
		765	known to other nodes for a completely different process, causing messages
		766	destined for that process to end up in an unrelated process.
		767
		768	AEMP never reuses port IDs, so old messages or old port IDs floating
		769	around in the network will not be sent to an unrelated port.
		770
		771	=item * Erlang uses unprotected connections, AEMP uses secure
		772	authentication and can use TLS.
		773
		774	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		775	securely authenticate nodes.
		776
		777	=item * The AEMP protocol is optimised for both text-based and binary
		778	communications.
		779
		780	The AEMP protocol, unlike the Erlang protocol, supports both
		781	language-independent text-only protocols (good for debugging) and binary,
		782	language-specific serialisers (e.g. Storable).
		783
		784	It has also been carefully designed to be implementable in other languages
		785	with a minimum of work while gracefully degrading fucntionality to make the
		786	protocol simple.
		787
		788	=item * AEMP has more flexible monitoring options than Erlang.
		789
		790	In Erlang, you can chose to receive I<all> exit signals as messages
		791	or I<none>, there is no in-between, so monitoring single processes is
		792	difficult to implement. Monitoring in AEMP is more flexible than in
		793	Erlang, as one can choose between automatic kill, exit message or callback
		794	on a per-process basis.
		795
		796	=item * Erlang tries to hide remote/local connections, AEMP does not.
		797
		798	Monitoring in Erlang is not an indicator of process death/crashes,
		799	as linking is (except linking is unreliable in Erlang).
		800
		801	In AEMP, you don't "look up" registered port names or send to named ports
		802	that might or might not be persistent. Instead, you normally spawn a port
		803	on the remote node. The init function monitors the you, and you monitor
		804	the remote port. Since both monitors are local to the node, they are much
		805	more reliable.
		806
		807	This also saves round-trips and avoids sending messages to the wrong port
		808	(hard to do in Erlang).
		809
		810	=back
		811
		812	=head1 RATIONALE
		813
		814	=over 4
		815
		816	=item Why strings for ports and noderefs, why not objects?
		817
		818	We considered "objects", but found that the actual number of methods
		819	thatc an be called are very low. Since port IDs and noderefs travel over
		820	the network frequently, the serialising/deserialising would add lots of
		821	overhead, as well as having to keep a proxy object.
		822
		823	Strings can easily be printed, easily serialised etc. and need no special
		824	procedures to be "valid".
		825
		826	And a a miniport consists of a single closure stored in a global hash - it
		827	can't become much cheaper.
		828
		829	=item Why favour JSON, why not real serialising format such as Storable?
		830
		831	In fact, any AnyEvent::MP node will happily accept Storable as framing
		832	format, but currently there is no way to make a node use Storable by
		833	default.
		834
		835	The default framing protocol is JSON because a) JSON::XS is many times
		836	faster for small messages and b) most importantly, after years of
		837	experience we found that object serialisation is causing more problems
		838	than it gains: Just like function calls, objects simply do not travel
		839	easily over the network, mostly because they will always be a copy, so you
		840	always have to re-think your design.
		841
		842	Keeping your messages simple, concentrating on data structures rather than
		843	objects, will keep your messages clean, tidy and efficient.
422		844
423	=back	845	=back
424		846
425	=head1 SEE ALSO	847	=head1 SEE ALSO
426		848

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Revision 1.57 by root, Sat Aug 15 04:34:34 2009 UTC