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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.9 by root, Sun Aug 2 15:47:04 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
32	At the moment, this module family is severly brokena nd underdocumented,	43	At the moment, this module family is severly broken and underdocumented,
33	so do not use. This was uploaded mainly to resreve the CPAN namespace -	44	so do not use. This was uploaded mainly to reserve the CPAN namespace -
34	stay tuned!	45	stay tuned! The basic API should be finished, however.
35		46
36	=head1 CONCEPTS	47	=head1 CONCEPTS
37		48
38	=over 4	49	=over 4
39		50
40	=item port	51	=item port
41		52
42	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).
43	you can register C<rcv> handlers with. All C<rcv> handlers will receive	54
44	messages they match, messages will not be queued.	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.
45		58
46	=item port id - C<noderef#portname>	59	=item port id - C<noderef#portname>
47		60
48	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	61	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as
49	by a port name (a printable string of unspecified format).	62	separator, and a port name (a printable string of unspecified format). An
		63	exception is the the node port, whose ID is identical to its node
		64	reference.
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 master node only). Only when they epxlicitly "become	73	master node only) or public nodes (connectable from unrelated nodes).
59	public" can you send them messages from unrelated other nodes.
60		74
61	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	75	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
62		76
63	A noderef 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
64	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
65	node (for public nodes).	79	node (for public nodes).
66		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
67	=back	90	=back
68		91
69	=head1 VARIABLES/FUNCTIONS	92	=head1 VARIABLES/FUNCTIONS
70		93
71	=over 4	94	=over 4
…		…
82		105
83	use AE ();	106	use AE ();
84		107
85	use base "Exporter";	108	use base "Exporter";
86		109
87	our $VERSION = '0.02';	110	our $VERSION = '0.1';
88	our @EXPORT = qw(	111	our @EXPORT = qw(
89	NODE $NODE $PORT snd rcv _any_	112	NODE $NODE *SELF node_of _any_
90	create_port create_port_on	113	resolve_node initialise_node
91	become_slave become_public	114	snd rcv mon kil reg psub
		115	port
92	);	116	);
93		117
		118	our $SELF;
		119
		120	sub _self_die() {
		121	my $msg = $@;
		122	$msg =~ s/\n+$// unless ref $msg;
		123	kil $SELF, die => $msg;
		124	}
		125
94	=item NODE / $NODE	126	=item $thisnode = NODE / $NODE
95		127
96	The C<NODE ()> function and the C<$NODE> variable contain the noderef of	128	The C<NODE> function returns, and the C<$NODE> variable contains
97	the local node. The value is initialised by a call to C<become_public> or	129	the noderef of the local node. The value is initialised by a call
98	C<become_slave>, after which all local port identifiers become invalid.	130	to C<become_public> or C<become_slave>, after which all local port
		131	identifiers become invalid.
99		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
100	=item snd $portid, type => @data	241	=item snd $port, type => @data
101		242
102	=item snd $portid, @msg	243	=item snd $port, @msg
103		244
104	Send the given message to the given port ID, which can identify either	245	Send the given message to the given port ID, which can identify either
105	a local or a remote port, and can be either a string or soemthignt hat	246	a local or a remote port, and can be either a string or soemthignt hat
106	stringifies a sa port ID (such as a port object :).	247	stringifies a sa port ID (such as a port object :).
107		248
…		…
117	JSON is used, then only strings, numbers and arrays and hashes consisting	258	JSON is used, then only strings, numbers and arrays and hashes consisting
118	of those are allowed (no objects). When Storable is used, then anything	259	of those are allowed (no objects). When Storable is used, then anything
119	that Storable can serialise and deserialise is allowed, and for the local	260	that Storable can serialise and deserialise is allowed, and for the local
120	node, anything can be passed.	261	node, anything can be passed.
121		262
122	=item $local_port = create_port	263	=item $local_port = port
123		264
124	Create a new local port object. See the next section for allowed methods.	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.
125		268
126	=cut	269	=item $port = port { my @msg = @_; $finished }
127		270
128	sub create_port {	271	Creates a "miniport", that is, a very lightweight port without any pattern
129	my $id = "$AnyEvent::MP::Base::UNIQ." . ++$AnyEvent::MP::Base::ID;	272	matching behind it, and returns its ID. Semantically the same as creating
		273	a port and calling C<rcv $port, $callback> on it.
130		274
131	my $self = bless {	275	The block will be called for every message received on the port. When the
132	id => "$NODE#$id",	276	callback returns a true value its job is considered "done" and the port
133	names => [$id],	277	will be destroyed. Otherwise it will stay alive.
134	}, "AnyEvent::MP::Port";
135		278
136	$AnyEvent::MP::Base::PORT{$id} = sub {	279	The message will be passed as-is, no extra argument (i.e. no port id) will
137	unshift @_, $self;	280	be passed to the callback.
138		281
139	for (@{ $self->{rc0}{$_[1]} }) {	282	If you need the local port id in the callback, this works nicely:
140	$_ && &{$_->[0]}
141	&& undef $_;
142	}
143		283
144	for (@{ $self->{rcv}{$_[1]} }) {	284	my $port; $port = port {
145	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	285	snd $otherport, reply => $port;
146	&& &{$_->[0]}
147	&& undef $_;
148	}
149
150	for (@{ $self->{any} }) {
151	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
152	&& &{$_->[0]}
153	&& undef $_;
154	}
155	};	286	};
156		287
157	$self	288	=cut
		289
		290	sub rcv($@);
		291
		292	sub port(;&) {
		293	my $id = "$UNIQ." . $ID++;
		294	my $port = "$NODE#$id";
		295
		296	if (@_) {
		297	rcv $port, shift;
		298	} else {
		299	$PORT{$id} = sub { }; # nop
		300	}
		301
		302	$port
158	}	303	}
159		304
160	package AnyEvent::MP::Port;	305	=item reg $port, $name
161		306
162	=back	307	=item reg $name
163		308
164	=head1 METHODS FOR PORT OBJECTS	309	Registers the given port (or C<$SELF><<< if missing) under the name
		310	C<$name>. If the name already exists it is replaced.
165		311
166	=over 4	312	A port can only be registered under one well known name.
167		313
168	=item "$port"	314	A port automatically becomes unregistered when it is killed.
169		315
170	A port object stringifies to its port ID, so can be used directly for
171	C<snd> operations.
172
173	=cut	316	=cut
174		317
175	use overload	318	sub reg(@) {
176	'""' => sub { $_[0]{id} },	319	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
177	fallback => 1;
178		320
179	=item $port->rcv (type => $callback->($port, @msg))	321	$REG{$_[0]} = $port;
		322	}
180		323
181	=item $port->rcv ($smartmatch => $callback->($port, @msg))	324	=item rcv $port, $callback->(@msg)
182		325
		326	Replaces the callback on the specified miniport (after converting it to
		327	one if required).
		328
		329	=item rcv $port, tagstring => $callback->(@msg), ...
		330
		331	=item rcv $port, $smartmatch => $callback->(@msg), ...
		332
183	=item $port->rcv ([$smartmatch...] => $callback->($port, @msg))	333	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
184		334
185	Register a callback on the given port.	335	Register callbacks to be called on matching messages on the given full
		336	port (after converting it to one if required) and return the port.
186		337
187	The callback has to return a true value when its work is done, after	338	The callback has to return a true value when its work is done, after
188	which is will be removed, or a false value in which case it will stay	339	which is will be removed, or a false value in which case it will stay
189	registered.	340	registered.
190		341
		342	The global C<$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
191	If the match is an array reference, then it will be matched against the	348	If the match is an array reference, then it will be matched against the
192	first elements of the message, otherwise only the first element is being	349	first elements of the message, otherwise only the first element is being
193	matched.	350	matched.
194		351
195	Any element in the match that is specified as C<_any_> (a function	352	Any element in the match that is specified as C<_any_> (a function
…		…
197		354
198	While not required, it is highly recommended that the first matching	355	While not required, it is highly recommended that the first matching
199	element is a string identifying the message. The one-string-only match is	356	element is a string identifying the message. The one-string-only match is
200	also the most efficient match (by far).	357	also the most efficient match (by far).
201		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 $otherport, reply =>
		370	rcv port,
		371	msg1 => sub { ...; 0 },
		372	...
		373	;
		374
202	=cut	375	=cut
203		376
204	sub rcv($@) {	377	sub rcv($@) {
205	my ($self, $match, $cb) = @_;	378	my $port = shift;
		379	my ($noderef, $portid) = split /#/, $port, 2;
206		380
207	if (!ref $match) {	381	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
208	push @{ $self->{rc0}{$match} }, [$cb];	382	or Carp::croak "$port: rcv can only be called on local ports, caught";
209	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	383
210	my ($type, @match) = @$match;	384	if (@_ == 1) {
211	@match	385	my $cb = shift;
212	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	386	delete $PORT_DATA{$portid};
213	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	387	$PORT{$portid} = sub {
		388	local $SELF = $port;
		389	eval {
		390	&$cb
		391	and kil $port;
		392	};
		393	_self_die if $@;
		394	};
214	} else {	395	} else {
		396	my $self = $PORT_DATA{$portid} \|\|= do {
		397	my $self = bless {
		398	id => $port,
		399	}, "AnyEvent::MP::Port";
		400
		401	$PORT{$portid} = sub {
		402	local $SELF = $port;
		403
		404	eval {
		405	for (@{ $self->{rc0}{$_[0]} }) {
		406	$_ && &{$_->[0]}
		407	&& undef $_;
		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	}
		421	};
		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 {
215	push @{ $self->{any} }, [$cb, $match];	442	push @{ $self->{any} }, [$cb, $match];
		443	}
		444	}
		445	}
		446
		447	$port
		448	}
		449
		450	=item $closure = psub { BLOCK }
		451
		452	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		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.
		455
		456	This is useful when you register callbacks from C<rcv> callbacks:
		457
		458	rcv delayed_reply => sub {
		459	my ($delay, @reply) = @_;
		460	my $timer = AE::timer $delay, 0, psub {
		461	snd @reply, $SELF;
		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	}
216	}	485	}
217	}	486	}
218		487
219	=item $port->register ($name)	488	=item $guard = mon $port, $cb->(@reason)
220		489
221	Registers the given port under the well known name C<$name>. If the name	490	=item $guard = mon $port, $rcvport
222	already exists it is replaced.
223		491
224	A port can only be registered under one well known name.	492	=item $guard = mon $port
225		493
226	=cut	494	=item $guard = mon $port, $rcvport, @msg
227		495
228	sub register {	496	Monitor the given port and do something when the port is killed, and
229	my ($self, $name) = @_;	497	optionally return a guard that can be used to stop monitoring again.
230		498
231	$self->{wkname} = $name;	499	In the first form (callback), the callback is simply called with any
232	$AnyEvent::MP::Base::WKP{$name} = "$self";	500	number of C<@reason> elements (no @reason means that the port was deleted
		501	"normally"). Note also that I<< the callback B<must> never die >>, so use
		502	C<eval> if unsure.
		503
		504	In the second form (another port given), the other port (C<$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) }
233	}	559	}
234		560
235	=item $port->destroy	561	=item $guard = mon_guard $port, $ref, $ref...
236		562
237	Explicitly destroy/remove/nuke/vaporise the port.	563	Monitors the given C<$port> and keeps the passed references. When the port
		564	is killed, the references will be freed.
238		565
239	Ports are normally kept alive by there mere existance alone, and need to	566	Optionally returns a guard that will stop the monitoring.
240	be destroyed explicitly.
241		567
242	=cut	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:
243		570
244	sub destroy {	571	$port->rcv (start => sub {
245	my ($self) = @_;	572	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		573	undef $timer if 0.9 < rand;
		574	});
		575	});
246		576
247	delete $AnyEvent::MP::Base::WKP{ $self->{wkname} };	577	=cut
248		578
249	delete $AnyEvent::MP::Base::PORT{$_}	579	sub mon_guard {
250	for @{ $self->{names} };	580	my ($port, @refs) = @_;
		581
		582	#TODO: mon-less form?
		583
		584	mon $port, sub { 0 && @refs }
251	}	585	}
252		586
253	=back	587	=item kil $port[, @reason]
254		588
255	=head1 FUNCTIONS FOR NODES	589	Kill the specified port with the given C<@reason>.
256		590
257	=over 4	591	If no C<@reason> is specified, then the port is killed "normally" (linked
		592	ports will not be kileld, or even notified).
258		593
259	=item mon $noderef, $callback->($noderef, $status, $)	594	Otherwise, linked ports get killed with the same reason (second form of
		595	C<mon>, see below).
260		596
261	Monitors the given noderef.	597	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		598	will be reported as reason C<< die => $@ >>.
262		599
263	=item become_public endpoint...	600	Transport/communication errors are reported as C<< transport_error =>
264		601	$message >>.
265	Tells the node to become a public node, i.e. reachable from other nodes.
266
267	If no arguments are given, or the first argument is C<undef>, then
268	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the
269	local nodename resolves to.
270
271	Otherwise the first argument must be an array-reference with transport
272	endpoints ("ip:port", "hostname:port") or port numbers (in which case the
273	local nodename is used as hostname). The endpoints are all resolved and
274	will become the node reference.
275
276	=cut
277		602
278	=back	603	=back
279		604
280	=head1 NODE MESSAGES	605	=head1 NODE MESSAGES
281		606
282	Nodes understand the following messages sent to them. Many of them take	607	Nodes understand the following messages sent to them. Many of them take
283	arguments called C<@reply>, which will simply be used to compose a reply	608	arguments called C<@reply>, which will simply be used to compose a reply
284	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	609	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
285	the remaining arguments are simply the message data.	610	the remaining arguments are simply the message data.
286		611
		612	While other messages exist, they are not public and subject to change.
		613
287	=over 4	614	=over 4
288		615
289	=cut	616	=cut
290		617
291	=item wkp => $name, @reply	618	=item lookup => $name, @reply
292		619
293	Replies with the port ID of the specified well-known port, or C<undef>.	620	Replies with the port ID of the specified well-known port, or C<undef>.
294		621
295	=item devnull => ...	622	=item devnull => ...
296		623
…		…
319	snd $NODE, time => $myport, timereply => 1, 2;	646	snd $NODE, time => $myport, timereply => 1, 2;
320	# => snd $myport, timereply => 1, 2, <time>	647	# => snd $myport, timereply => 1, 2, <time>
321		648
322	=back	649	=back
323		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).
		757
		758	=back
		759
324	=head1 SEE ALSO	760	=head1 SEE ALSO
325		761
326	L<AnyEvent>.	762	L<AnyEvent>.
327		763
328	=head1 AUTHOR	764	=head1 AUTHOR

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Revision 1.37 by root, Fri Aug 7 16:47:23 2009 UTC