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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.3 by root, Sat Aug 1 07:11:45 2009 UTC vs.
Revision 1.55 by root, Fri Aug 14 23:17:17 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		46	AnyEvent::MP::Intro - outdated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	=back
		203
		204	This function will block until all nodes have been resolved and, for slave
		205	nodes, until it has successfully established a connection to a master
		206	server.
		207
		208	Example: become a public node listening on the guessed noderef, or the one
		209	specified via C<aemp> for the current node. This should be the most common
		210	form of invocation for "daemon"-type nodes.
		211
		212	initialise_node;
		213
		214	Example: become a slave node to any of the the seednodes specified via
		215	C<aemp>. This form is often used for commandline clients.
		216
		217	initialise_node "slave/";
		218
		219	Example: become a slave node to any of the specified master servers. This
		220	form is also often used for commandline clients.
		221
		222	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		223
		224	Example: become a public node, and try to contact some well-known master
		225	servers to become part of the network.
		226
		227	initialise_node undef, "master1", "master2";
		228
		229	Example: become a public node listening on port C<4041>.
		230
		231	initialise_node 4041;
		232
		233	Example: become a public node, only visible on localhost port 4044.
		234
		235	initialise_node "localhost:4044";
		236
		237	=item $cv = resolve_node $noderef
		238
		239	Takes an unresolved node reference that may contain hostnames and
		240	abbreviated IDs, resolves all of them and returns a resolved node
		241	reference.
		242
		243	In addition to C<address:port> pairs allowed in resolved noderefs, the
		244	following forms are supported:
		245
		246	=over 4
		247
		248	=item the empty string
		249
		250	An empty-string component gets resolved as if the default port (4040) was
		251	specified.
		252
		253	=item naked port numbers (e.g. C<1234>)
		254
		255	These are resolved by prepending the local nodename and a colon, to be
		256	further resolved.
		257
		258	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		259
		260	These are resolved by using AnyEvent::DNS to resolve them, optionally
		261	looking up SRV records for the C<aemp=4040> port, if no port was
		262	specified.
		263
		264	=back
		265
		266	=item $SELF
		267
		268	Contains the current port id while executing C<rcv> callbacks or C<psub>
		269	blocks.
		270
		271	=item SELF, %SELF, @SELF...
		272
		273	Due to some quirks in how perl exports variables, it is impossible to
		274	just export C<$SELF>, all the symbols called C<SELF> are exported by this
		275	module, but only C<$SELF> is currently used.
		276
155	=item snd $portid, type => @data	277	=item snd $port, type => @data
156		278
157	=item snd $portid, @msg	279	=item snd $port, @msg
158		280
159	Send the given message to the given port ID, which can identify either a	281	Send the given message to the given port ID, which can identify either
160	local or a remote port.	282	a local or a remote port, and must be a port ID.
161		283
162	While the message can be about anything, it is highly recommended to use	284	While the message can be about anything, it is highly recommended to use a
163	a constant string as first element.	285	string as first element (a port ID, or some word that indicates a request
		286	type etc.).
164		287
165	The message data effectively becomes read-only after a call to this	288	The message data effectively becomes read-only after a call to this
166	function: modifying any argument is not allowed and can cause many	289	function: modifying any argument is not allowed and can cause many
167	problems.	290	problems.
168		291
…		…
170	JSON is used, then only strings, numbers and arrays and hashes consisting	293	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	294	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	295	that Storable can serialise and deserialise is allowed, and for the local
173	node, anything can be passed.	296	node, anything can be passed.
174		297
175	=cut	298	=item $local_port = port
176		299
177	sub snd($@) {	300	Create a new local port object and returns its port ID. Initially it has
178	my ($noderef, $port) = split /#/, shift, 2;	301	no callbacks set and will throw an error when it receives messages.
179		302
180	add_node $noderef	303	=item $local_port = port { my @msg = @_ }
181	unless exists $NODE{$noderef};
182		304
183	$NODE{$noderef}->send (["$port", [@_]]);	305	Creates a new local port, and returns its ID. Semantically the same as
		306	creating a port and calling C<rcv $port, $callback> on it.
		307
		308	The block will be called for every message received on the port, with the
		309	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		310	port to be C<kil>ed. The message will be passed as-is, no extra argument
		311	(i.e. no port ID) will be passed to the callback.
		312
		313	If you want to stop/destroy the port, simply C<kil> it:
		314
		315	my $port = port {
		316	my @msg = @_;
		317	...
		318	kil $SELF;
		319	};
		320
		321	=cut
		322
		323	sub rcv($@);
		324
		325	sub _kilme {
		326	die "received message on port without callback";
184	}	327	}
185		328
		329	sub port(;&) {
		330	my $id = "$UNIQ." . $ID++;
		331	my $port = "$NODE#$id";
		332
		333	rcv $port, shift \|\| \&_kilme;
		334
		335	$port
		336	}
		337
186	=item rcv $portid, type => $callback->(@msg)	338	=item rcv $local_port, $callback->(@msg)
187		339
188	=item rcv $portid, $smartmatch => $callback->(@msg)	340	Replaces the default callback on the specified port. There is no way to
		341	remove the default callback: use C<sub { }> to disable it, or better
		342	C<kil> the port when it is no longer needed.
189		343
190	=item rcv $portid, [$smartmatch...] => $callback->(@msg)	344	The global C<$SELF> (exported by this module) contains C<$port> while
		345	executing the callback. Runtime errors during callback execution will
		346	result in the port being C<kil>ed.
191		347
192	Register a callback on the port identified by C<$portid>, which I<must> be	348	The default callback received all messages not matched by a more specific
193	a local port.	349	C<tag> match.
194		350
195	The callback has to return a true value when its work is done, after	351	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
196	which is will be removed, or a false value in which case it will stay
197	registered.
198		352
199	If the match is an array reference, then it will be matched against the	353	Register (or replace) callbacks to be called on messages starting with the
200	first elements of the message, otherwise only the first element is being	354	given tag on the given port (and return the port), or unregister it (when
201	matched.	355	C<$callback> is C<$undef> or missing). There can only be one callback
		356	registered for each tag.
202		357
203	Any element in the match that is specified as C<_any_> (a function	358	The original message will be passed to the callback, after the first
204	exported by this module) matches any single element of the message.	359	element (the tag) has been removed. The callback will use the same
		360	environment as the default callback (see above).
205		361
206	While not required, it is highly recommended that the first matching	362	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	363
208	also the most efficient match (by far).	364	my $port = rcv port,
		365	msg1 => sub { ... },
		366	msg2 => sub { ... },
		367	;
		368
		369	Example: create a port, bind receivers and send it in a message elsewhere
		370	in one go:
		371
		372	snd $otherport, reply =>
		373	rcv port,
		374	msg1 => sub { ... },
		375	...
		376	;
		377
		378	Example: temporarily register a rcv callback for a tag matching some port
		379	(e.g. for a rpc reply) and unregister it after a message was received.
		380
		381	rcv $port, $otherport => sub {
		382	my @reply = @_;
		383
		384	rcv $SELF, $otherport;
		385	};
209		386
210	=cut	387	=cut
211		388
212	sub rcv($@) {	389	sub rcv($@) {
213	my ($port, $match, $cb) = @_;	390	my $port = shift;
214
215	my $port = $PORT{$port}
216	or do {
217	my ($noderef, $lport) = split /#/, $port;	391	my ($noderef, $portid) = split /#/, $port, 2;
218	"AnyEvent::MP::Node::Self" eq ref $NODE{$noderef}	392
		393	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
219	or Carp::croak "$port: can only rcv on local ports";	394	or Carp::croak "$port: rcv can only be called on local ports, caught";
220		395
221	$PORT{$lport}	396	while (@_) {
222	or Carp::croak "$port: port does not exist";	397	if (ref $_[0]) {
223		398	if (my $self = $PORT_DATA{$portid}) {
224	$PORT{$port} = $PORT{$lport} # also return	399	"AnyEvent::MP::Port" eq ref $self
225	};	400	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
226		401
227	if (!ref $match) {	402	$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 {	403	} else {
235	push @{ $port->{any} }, [$cb, $match];	404	my $cb = shift;
236	}	405	$PORT{$portid} = sub {
237	}	406	local $SELF = $port;
238		407	eval { &$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	}	408	};
299	$cv->end;	409	}
		410	} elsif (defined $_[0]) {
		411	my $self = $PORT_DATA{$portid} \|\|= do {
		412	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		413
		414	$PORT{$portid} = sub {
		415	local $SELF = $port;
		416
		417	if (my $cb = $self->[1]{$_[0]}) {
		418	shift;
		419	eval { &$cb }; _self_die if $@;
		420	} else {
		421	&{ $self->[0] };
		422	}
		423	};
		424
		425	$self
300	};	426	};
301		427
302	# my (undef, undef, undef, undef, @ipv4) = gethostbyname $nodename;	428	"AnyEvent::MP::Port" eq ref $self
303	#	429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
304	# for (@ipv4) {	430
305	# push @res, [	431	my ($tag, $cb) = splice @_, 0, 2;
306	# $pri,	432
307	# AnyEvent::Socket::format_hostport AnyEvent::Socket::format_address $_, $t \|\| $DEFAULT_PORT,	433	if (defined $cb) {
308	# ];	434	$self->[1]{$tag} = $cb;
309	# }
310	} else {	435	} else {
311	my ($host, $port) = AnyEvent::Socket::parse_hostport $t, "aemp=$DEFAULT_PORT"	436	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	}	437	}
325	}	438	}
326	}	439	}
327		440
328	$cv->end;	441	$port
329
330	$cv
331	}	442	}
332		443
333	sub become_public {	444	=item $closure = psub { BLOCK }
334	return if $PUBLIC;
335		445
336	my $noderef = join ",", ref $_[0] ? @{+shift} : shift;	446	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
337	my @args = @_;	447	closure is executed, sets up the environment in the same way as in C<rcv>
		448	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
338		449
339	$NODE = (normalise_noderef $noderef)->recv;	450	This is useful when you register callbacks from C<rcv> callbacks:
340		451
341	for my $t (split /,/, $NODE) {	452	rcv delayed_reply => sub {
342	$NODE{$t} = $NODE{""};	453	my ($delay, @reply) = @_;
343		454	my $timer = AE::timer $delay, 0, psub {
344	my ($host, $port) = AnyEvent::Socket::parse_hostport $t;	455	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	;	456	};
		457	};
		458
		459	=cut
		460
		461	sub psub(&) {
		462	my $cb = shift;
		463
		464	my $port = $SELF
		465	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		466
		467	sub {
		468	local $SELF = $port;
		469
		470	if (wantarray) {
		471	my @res = eval { &$cb };
		472	_self_die if $@;
		473	@res
		474	} else {
		475	my $res = eval { &$cb };
		476	_self_die if $@;
		477	$res
		478	}
362	}	479	}
363
364	$PUBLIC = 1;
365	}	480	}
366		481
367	#############################################################################	482	=item $guard = mon $port, $cb->(@reason)
368	# self node code
369		483
370	sub _new_port($) {	484	=item $guard = mon $port, $rcvport
371	my ($name) = @_;
372		485
		486	=item $guard = mon $port
		487
		488	=item $guard = mon $port, $rcvport, @msg
		489
		490	Monitor the given port and do something when the port is killed or
		491	messages to it were lost, and optionally return a guard that can be used
		492	to stop monitoring again.
		493
		494	C<mon> effectively guarantees that, in the absence of hardware failures,
		495	that after starting the monitor, either all messages sent to the port
		496	will arrive, or the monitoring action will be invoked after possible
		497	message loss has been detected. No messages will be lost "in between"
		498	(after the first lost message no further messages will be received by the
		499	port). After the monitoring action was invoked, further messages might get
		500	delivered again.
		501
		502	In the first form (callback), the callback is simply called with any
		503	number of C<@reason> elements (no @reason means that the port was deleted
		504	"normally"). Note also that I<< the callback B<must> never die >>, so use
		505	C<eval> if unsure.
		506
		507	In the second form (another port given), the other port (C<$rcvport>)
		508	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		509	"normal" kils nothing happens, while under all other conditions, the other
		510	port is killed with the same reason.
		511
		512	The third form (kill self) is the same as the second form, except that
		513	C<$rvport> defaults to C<$SELF>.
		514
		515	In the last form (message), a message of the form C<@msg, @reason> will be
		516	C<snd>.
		517
		518	As a rule of thumb, monitoring requests should always monitor a port from
		519	a local port (or callback). The reason is that kill messages might get
		520	lost, just like any other message. Another less obvious reason is that
		521	even monitoring requests can get lost (for exmaple, when the connection
		522	to the other node goes down permanently). When monitoring a port locally
		523	these problems do not exist.
		524
		525	Example: call a given callback when C<$port> is killed.
		526
		527	mon $port, sub { warn "port died because of <@_>\n" };
		528
		529	Example: kill ourselves when C<$port> is killed abnormally.
		530
		531	mon $port;
		532
		533	Example: send us a restart message when another C<$port> is killed.
		534
		535	mon $port, $self => "restart";
		536
		537	=cut
		538
		539	sub mon {
373	my ($noderef, $portname) = split /#/, $name;	540	my ($noderef, $port) = split /#/, shift, 2;
374		541
375	$PORT{$name} =	542	my $node = $NODE{$noderef} \|\| add_node $noderef;
376	$PORT{$portname} = {	543
377	names => [$name, $portname],	544	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		545
		546	unless (ref $cb) {
		547	if (@_) {
		548	# send a kill info message
		549	my (@msg) = ($cb, @_);
		550	$cb = sub { snd @msg, @_ };
		551	} else {
		552	# simply kill other port
		553	my $port = $cb;
		554	$cb = sub { kil $port, @_ if @_ };
		555	}
		556	}
		557
		558	$node->monitor ($port, $cb);
		559
		560	defined wantarray
		561	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		562	}
		563
		564	=item $guard = mon_guard $port, $ref, $ref...
		565
		566	Monitors the given C<$port> and keeps the passed references. When the port
		567	is killed, the references will be freed.
		568
		569	Optionally returns a guard that will stop the monitoring.
		570
		571	This function is useful when you create e.g. timers or other watchers and
		572	want to free them when the port gets killed:
		573
		574	$port->rcv (start => sub {
		575	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		576	undef $timer if 0.9 < rand;
		577	});
		578	});
		579
		580	=cut
		581
		582	sub mon_guard {
		583	my ($port, @refs) = @_;
		584
		585	#TODO: mon-less form?
		586
		587	mon $port, sub { 0 && @refs }
		588	}
		589
		590	=item kil $port[, @reason]
		591
		592	Kill the specified port with the given C<@reason>.
		593
		594	If no C<@reason> is specified, then the port is killed "normally" (linked
		595	ports will not be kileld, or even notified).
		596
		597	Otherwise, linked ports get killed with the same reason (second form of
		598	C<mon>, see below).
		599
		600	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		601	will be reported as reason C<< die => $@ >>.
		602
		603	Transport/communication errors are reported as C<< transport_error =>
		604	$message >>.
		605
		606	=cut
		607
		608	=item $port = spawn $node, $initfunc[, @initdata]
		609
		610	Creates a port on the node C<$node> (which can also be a port ID, in which
		611	case it's the node where that port resides).
		612
		613	The port ID of the newly created port is return immediately, and it is
		614	permissible to immediately start sending messages or monitor the port.
		615
		616	After the port has been created, the init function is
		617	called. This function must be a fully-qualified function name
		618	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		619	program, use C<::name>.
		620
		621	If the function doesn't exist, then the node tries to C<require>
		622	the package, then the package above the package and so on (e.g.
		623	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		624	exists or it runs out of package names.
		625
		626	The init function is then called with the newly-created port as context
		627	object (C<$SELF>) and the C<@initdata> values as arguments.
		628
		629	A common idiom is to pass your own port, monitor the spawned port, and
		630	in the init function, monitor the original port. This two-way monitoring
		631	ensures that both ports get cleaned up when there is a problem.
		632
		633	Example: spawn a chat server port on C<$othernode>.
		634
		635	# this node, executed from within a port context:
		636	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		637	mon $server;
		638
		639	# init function on C<$othernode>
		640	sub connect {
		641	my ($srcport) = @_;
		642
		643	mon $srcport;
		644
		645	rcv $SELF, sub {
		646	...
		647	};
		648	}
		649
		650	=cut
		651
		652	sub _spawn {
		653	my $port = shift;
		654	my $init = shift;
		655
		656	local $SELF = "$NODE#$port";
		657	eval {
		658	&{ load_func $init }
378	};	659	};
		660	_self_die if $@;
379	}	661	}
380		662
381	$NODE{""} = new AnyEvent::MP::Node::Self noderef => $NODE;	663	sub spawn(@) {
382	_new_port "";	664	my ($noderef, undef) = split /#/, shift, 2;
383		665
384	rcv "", relay => \&snd;	666	my $id = "$RUNIQ." . $ID++;
		667
		668	$_[0] =~ /::/
		669	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		670
		671	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		672
		673	"$noderef#$id"
		674	}
		675
		676	=back
		677
		678	=head1 NODE MESSAGES
		679
		680	Nodes understand the following messages sent to them. Many of them take
		681	arguments called C<@reply>, which will simply be used to compose a reply
		682	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
		683	the remaining arguments are simply the message data.
		684
		685	While other messages exist, they are not public and subject to change.
		686
		687	=over 4
		688
		689	=cut
		690
		691	=item lookup => $name, @reply
		692
		693	Replies with the port ID of the specified well-known port, or C<undef>.
		694
		695	=item devnull => ...
		696
		697	Generic data sink/CPU heat conversion.
		698
		699	=item relay => $port, @msg
		700
		701	Simply forwards the message to the given port.
		702
		703	=item eval => $string[ @reply]
		704
		705	Evaluates the given string. If C<@reply> is given, then a message of the
		706	form C<@reply, $@, @evalres> is sent.
		707
		708	Example: crash another node.
		709
		710	snd $othernode, eval => "exit";
		711
		712	=item time => @reply
		713
		714	Replies the the current node time to C<@reply>.
		715
		716	Example: tell the current node to send the current time to C<$myport> in a
		717	C<timereply> message.
		718
		719	snd $NODE, time => $myport, timereply => 1, 2;
		720	# => snd $myport, timereply => 1, 2, <time>
		721
		722	=back
		723
		724	=head1 AnyEvent::MP vs. Distributed Erlang
		725
		726	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		727	== aemp node, Erlang process == aemp port), so many of the documents and
		728	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		729	sample:
		730
		731	http://www.Erlang.se/doc/programming_rules.shtml
		732	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		733	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		734	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		735
		736	Despite the similarities, there are also some important differences:
		737
		738	=over 4
		739
		740	=item * Node references contain the recipe on how to contact them.
		741
		742	Erlang relies on special naming and DNS to work everywhere in the
		743	same way. AEMP relies on each node knowing it's own address(es), with
		744	convenience functionality.
		745
		746	This means that AEMP requires a less tightly controlled environment at the
		747	cost of longer node references and a slightly higher management overhead.
		748
		749	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		750	uses "local ports are like remote ports".
		751
		752	The failure modes for local ports are quite different (runtime errors
		753	only) then for remote ports - when a local port dies, you I<know> it dies,
		754	when a connection to another node dies, you know nothing about the other
		755	port.
		756
		757	Erlang pretends remote ports are as reliable as local ports, even when
		758	they are not.
		759
		760	AEMP encourages a "treat remote ports differently" philosophy, with local
		761	ports being the special case/exception, where transport errors cannot
		762	occur.
		763
		764	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		765
		766	Erlang uses processes that selectively receive messages, and therefore
		767	needs a queue. AEMP is event based, queuing messages would serve no
		768	useful purpose. For the same reason the pattern-matching abilities of
		769	AnyEvent::MP are more limited, as there is little need to be able to
		770	filter messages without dequeing them.
		771
		772	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		773
		774	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		775
		776	Sending messages in Erlang is synchronous and blocks the process (and
		777	so does not need a queue that can overflow). AEMP sends are immediate,
		778	connection establishment is handled in the background.
		779
		780	=item * Erlang suffers from silent message loss, AEMP does not.
		781
		782	Erlang makes few guarantees on messages delivery - messages can get lost
		783	without any of the processes realising it (i.e. you send messages a, b,
		784	and c, and the other side only receives messages a and c).
		785
		786	AEMP guarantees correct ordering, and the guarantee that there are no
		787	holes in the message sequence.
		788
		789	=item * In Erlang, processes can be declared dead and later be found to be
		790	alive.
		791
		792	In Erlang it can happen that a monitored process is declared dead and
		793	linked processes get killed, but later it turns out that the process is
		794	still alive - and can receive messages.
		795
		796	In AEMP, when port monitoring detects a port as dead, then that port will
		797	eventually be killed - it cannot happen that a node detects a port as dead
		798	and then later sends messages to it, finding it is still alive.
		799
		800	=item * Erlang can send messages to the wrong port, AEMP does not.
		801
		802	In Erlang it is quite likely that a node that restarts reuses a process ID
		803	known to other nodes for a completely different process, causing messages
		804	destined for that process to end up in an unrelated process.
		805
		806	AEMP never reuses port IDs, so old messages or old port IDs floating
		807	around in the network will not be sent to an unrelated port.
		808
		809	=item * Erlang uses unprotected connections, AEMP uses secure
		810	authentication and can use TLS.
		811
		812	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		813	securely authenticate nodes.
		814
		815	=item * The AEMP protocol is optimised for both text-based and binary
		816	communications.
		817
		818	The AEMP protocol, unlike the Erlang protocol, supports both
		819	language-independent text-only protocols (good for debugging) and binary,
		820	language-specific serialisers (e.g. Storable).
		821
		822	It has also been carefully designed to be implementable in other languages
		823	with a minimum of work while gracefully degrading fucntionality to make the
		824	protocol simple.
		825
		826	=item * AEMP has more flexible monitoring options than Erlang.
		827
		828	In Erlang, you can chose to receive I<all> exit signals as messages
		829	or I<none>, there is no in-between, so monitoring single processes is
		830	difficult to implement. Monitoring in AEMP is more flexible than in
		831	Erlang, as one can choose between automatic kill, exit message or callback
		832	on a per-process basis.
		833
		834	=item * Erlang tries to hide remote/local connections, AEMP does not.
		835
		836	Monitoring in Erlang is not an indicator of process death/crashes,
		837	as linking is (except linking is unreliable in Erlang).
		838
		839	In AEMP, you don't "look up" registered port names or send to named ports
		840	that might or might not be persistent. Instead, you normally spawn a port
		841	on the remote node. The init function monitors the you, and you monitor
		842	the remote port. Since both monitors are local to the node, they are much
		843	more reliable.
		844
		845	This also saves round-trips and avoids sending messages to the wrong port
		846	(hard to do in Erlang).
		847
		848	=back
		849
		850	=head1 RATIONALE
		851
		852	=over 4
		853
		854	=item Why strings for ports and noderefs, why not objects?
		855
		856	We considered "objects", but found that the actual number of methods
		857	thatc an be called are very low. Since port IDs and noderefs travel over
		858	the network frequently, the serialising/deserialising would add lots of
		859	overhead, as well as having to keep a proxy object.
		860
		861	Strings can easily be printed, easily serialised etc. and need no special
		862	procedures to be "valid".
		863
		864	And a a miniport consists of a single closure stored in a global hash - it
		865	can't become much cheaper.
		866
		867	=item Why favour JSON, why not real serialising format such as Storable?
		868
		869	In fact, any AnyEvent::MP node will happily accept Storable as framing
		870	format, but currently there is no way to make a node use Storable by
		871	default.
		872
		873	The default framing protocol is JSON because a) JSON::XS is many times
		874	faster for small messages and b) most importantly, after years of
		875	experience we found that object serialisation is causing more problems
		876	than it gains: Just like function calls, objects simply do not travel
		877	easily over the network, mostly because they will always be a copy, so you
		878	always have to re-think your design.
		879
		880	Keeping your messages simple, concentrating on data structures rather than
		881	objects, will keep your messages clean, tidy and efficient.
385		882
386	=back	883	=back
387		884
388	=head1 SEE ALSO	885	=head1 SEE ALSO
389		886

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Revision 1.55 by root, Fri Aug 14 23:17:17 2009 UTC