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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.10 by root, Sun Aug 2 18:05:43 2009 UTC vs.
Revision 1.42 by root, Sun Aug 9 00:41:49 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	NODE # returns this node identifier
10	$NODE # contains this node identifier	9	$NODE # contains this node's noderef
		10	NODE # returns this node's noderef
		11	NODE $port # returns the noderef of the port
11		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# ports are message endpoints
		16
		17	# sending messages
12	snd $port, type => data...;	18	snd $port, type => data...;
		19	snd $port, @msg;
		20	snd @msg_with_first_element_being_a_port;
13		21
		22	# miniports
		23	my $miniport = port { my @msg = @_; 0 };
		24
		25	# full ports
		26	my $port = port;
14	rcv $port, smartmatch => $cb->($port, @msg);	27	rcv $port, smartmatch => $cb->(@msg);
15
16	# examples:
17	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
18	rcv $port1, pong => sub { warn "pong received\n" };	29	rcv $port, pong => sub { warn "pong received\n"; 0 };
19	snd $port2, ping => $port1;	30
		31	# remote ports
		32	my $port = spawn $node, $initfunc, @initdata;
20		33
21	# more, smarter, matches (_any_ is exported by this module)	34	# more, smarter, matches (_any_ is exported by this module)
22	rcv $port, [child_died => $pid] => sub { ...	35	rcv $port, [child_died => $pid] => sub { ...
23	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
24		37
		38	# monitoring
		39	mon $port, $cb->(@msg) # callback is invoked on death
		40	mon $port, $otherport # kill otherport on abnormal death
		41	mon $port, $otherport, @msg # send message on death
		42
25	=head1 DESCRIPTION	43	=head1 DESCRIPTION
26		44
27	This module (-family) implements a simple message passing framework.	45	This module (-family) implements a simple message passing framework.
28		46
29	Despite its simplicity, you can securely message other processes running	47	Despite its simplicity, you can securely message other processes running
30	on the same or other hosts.	48	on the same or other hosts.
31		49
		50	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		51	manual page.
		52
32	At the moment, this module family is severly brokena nd underdocumented,	53	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 -	54	so do not use. This was uploaded mainly to reserve the CPAN namespace -
34	stay tuned!	55	stay tuned! The basic API should be finished, however.
35		56
36	=head1 CONCEPTS	57	=head1 CONCEPTS
37		58
38	=over 4	59	=over 4
39		60
40	=item port	61	=item port
41		62
42	A port is something you can send messages to with the C<snd> function, and	63	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	64
44	messages they match, messages will not be queued.	65	Some ports allow you to register C<rcv> handlers that can match specific
		66	messages. All C<rcv> handlers will receive messages they match, messages
		67	will not be queued.
45		68
46	=item port id - C<noderef#portname>	69	=item port id - C<noderef#portname>
47		70
48	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	71	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).	72	separator, and a port name (a printable string of unspecified format). An
		73	exception is the the node port, whose ID is identical to its node
		74	reference.
50		75
51	=item node	76	=item node
52		77
53	A node is a single process containing at least one port - the node	78	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,	79	port. You can send messages to node ports to find existing ports or to
55	among other things.	80	create new ports, among other things.
56		81
57	Initially, nodes are either private (single-process only) or hidden	82	Nodes are either private (single-process only), slaves (connected to a
58	(connected to a master node only). Only when they epxlicitly "become	83	master node only) or public nodes (connectable from unrelated nodes).
59	public" can you send them messages from unrelated other nodes.
60		84
61	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	85	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
62		86
63	A noderef is a string that either uniquely identifies a given node (for	87	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	88	private and slave nodes), or contains a recipe on how to reach a given
65	node (for public nodes).	89	node (for public nodes).
66		90
		91	This recipe is simply a comma-separated list of C<address:port> pairs (for
		92	TCP/IP, other protocols might look different).
		93
		94	Node references come in two flavours: resolved (containing only numerical
		95	addresses) or unresolved (where hostnames are used instead of addresses).
		96
		97	Before using an unresolved node reference in a message you first have to
		98	resolve it.
		99
67	=back	100	=back
68		101
69	=head1 VARIABLES/FUNCTIONS	102	=head1 VARIABLES/FUNCTIONS
70		103
71	=over 4	104	=over 4
…		…
82		115
83	use AE ();	116	use AE ();
84		117
85	use base "Exporter";	118	use base "Exporter";
86		119
87	our $VERSION = '0.02';	120	our $VERSION = '0.1';
88	our @EXPORT = qw(	121	our @EXPORT = qw(
89	NODE $NODE $PORT snd rcv _any_	122	NODE $NODE *SELF node_of _any_
90	create_port create_port_on	123	resolve_node initialise_node
91	become_slave become_public	124	snd rcv mon kil reg psub spawn
		125	port
92	);	126	);
93		127
		128	our $SELF;
		129
		130	sub _self_die() {
		131	my $msg = $@;
		132	$msg =~ s/\n+$// unless ref $msg;
		133	kil $SELF, die => $msg;
		134	}
		135
94	=item NODE / $NODE	136	=item $thisnode = NODE / $NODE
95		137
96	The C<NODE ()> function and the C<$NODE> variable contain the noderef of	138	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	139	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.	140	to C<become_public> or C<become_slave>, after which all local port
		141	identifiers become invalid.
99		142
		143	=item $noderef = node_of $port
		144
		145	Extracts and returns the noderef from a portid or a noderef.
		146
		147	=item initialise_node $noderef, $seednode, $seednode...
		148
		149	=item initialise_node "slave/", $master, $master...
		150
		151	Before a node can talk to other nodes on the network it has to initialise
		152	itself - the minimum a node needs to know is it's own name, and optionally
		153	it should know the noderefs of some other nodes in the network.
		154
		155	This function initialises a node - it must be called exactly once (or
		156	never) before calling other AnyEvent::MP functions.
		157
		158	All arguments are noderefs, which can be either resolved or unresolved.
		159
		160	There are two types of networked nodes, public nodes and slave nodes:
		161
		162	=over 4
		163
		164	=item public nodes
		165
		166	For public nodes, C<$noderef> must either be a (possibly unresolved)
		167	noderef, in which case it will be resolved, or C<undef> (or missing), in
		168	which case the noderef will be guessed.
		169
		170	Afterwards, the node will bind itself on all endpoints and try to connect
		171	to all additional C<$seednodes> that are specified. Seednodes are optional
		172	and can be used to quickly bootstrap the node into an existing network.
		173
		174	=item slave nodes
		175
		176	When the C<$noderef> is the special string C<slave/>, then the node will
		177	become a slave node. Slave nodes cannot be contacted from outside and will
		178	route most of their traffic to the master node that they attach to.
		179
		180	At least one additional noderef is required: The node will try to connect
		181	to all of them and will become a slave attached to the first node it can
		182	successfully connect to.
		183
		184	=back
		185
		186	This function will block until all nodes have been resolved and, for slave
		187	nodes, until it has successfully established a connection to a master
		188	server.
		189
		190	Example: become a public node listening on the default node.
		191
		192	initialise_node;
		193
		194	Example: become a public node, and try to contact some well-known master
		195	servers to become part of the network.
		196
		197	initialise_node undef, "master1", "master2";
		198
		199	Example: become a public node listening on port C<4041>.
		200
		201	initialise_node 4041;
		202
		203	Example: become a public node, only visible on localhost port 4044.
		204
		205	initialise_node "locahost:4044";
		206
		207	Example: become a slave node to any of the specified master servers.
		208
		209	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		210
		211	=item $cv = resolve_node $noderef
		212
		213	Takes an unresolved node reference that may contain hostnames and
		214	abbreviated IDs, resolves all of them and returns a resolved node
		215	reference.
		216
		217	In addition to C<address:port> pairs allowed in resolved noderefs, the
		218	following forms are supported:
		219
		220	=over 4
		221
		222	=item the empty string
		223
		224	An empty-string component gets resolved as if the default port (4040) was
		225	specified.
		226
		227	=item naked port numbers (e.g. C<1234>)
		228
		229	These are resolved by prepending the local nodename and a colon, to be
		230	further resolved.
		231
		232	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		233
		234	These are resolved by using AnyEvent::DNS to resolve them, optionally
		235	looking up SRV records for the C<aemp=4040> port, if no port was
		236	specified.
		237
		238	=back
		239
		240	=item $SELF
		241
		242	Contains the current port id while executing C<rcv> callbacks or C<psub>
		243	blocks.
		244
		245	=item SELF, %SELF, @SELF...
		246
		247	Due to some quirks in how perl exports variables, it is impossible to
		248	just export C<$SELF>, all the symbols called C<SELF> are exported by this
		249	module, but only C<$SELF> is currently used.
		250
100	=item snd $portid, type => @data	251	=item snd $port, type => @data
101		252
102	=item snd $portid, @msg	253	=item snd $port, @msg
103		254
104	Send the given message to the given port ID, which can identify either	255	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	256	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 :).	257	stringifies a sa port ID (such as a port object :).
107		258
…		…
117	JSON is used, then only strings, numbers and arrays and hashes consisting	268	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	269	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	270	that Storable can serialise and deserialise is allowed, and for the local
120	node, anything can be passed.	271	node, anything can be passed.
121		272
122	=item $local_port = create_port	273	=item $local_port = port
123		274
124	Create a new local port object. See the next section for allowed methods.	275	Create a new local port object that can be used either as a pattern
		276	matching port ("full port") or a single-callback port ("miniport"),
		277	depending on how C<rcv> callbacks are bound to the object.
125		278
126	=cut	279	=item $port = port { my @msg = @_; $finished }
127		280
128	sub create_port {	281	Creates a "miniport", that is, a very lightweight port without any pattern
129	my $id = "$AnyEvent::MP::Base::UNIQ." . ++$AnyEvent::MP::Base::ID;	282	matching behind it, and returns its ID. Semantically the same as creating
		283	a port and calling C<rcv $port, $callback> on it.
130		284
131	my $self = bless {	285	The block will be called for every message received on the port. When the
132	id => "$NODE#$id",	286	callback returns a true value its job is considered "done" and the port
133	names => [$id],	287	will be destroyed. Otherwise it will stay alive.
134	}, "AnyEvent::MP::Port";
135		288
136	$AnyEvent::MP::Base::PORT{$id} = sub {	289	The message will be passed as-is, no extra argument (i.e. no port id) will
137	unshift @_, $self;	290	be passed to the callback.
138		291
139	for (@{ $self->{rc0}{$_[1]} }) {	292	If you need the local port id in the callback, this works nicely:
140	$_ && &{$_->[0]}
141	&& undef $_;
142	}
143		293
144	for (@{ $self->{rcv}{$_[1]} }) {	294	my $port; $port = port {
145	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	295	snd $otherport, reply => $port;
146	&& &{$_->[0]}
147	&& undef $_;
148	}
149
150	for (@{ $self->{any} }) {
151	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
152	&& &{$_->[0]}
153	&& undef $_;
154	}
155	};	296	};
156		297
157	$self	298	=cut
		299
		300	sub rcv($@);
		301
		302	sub port(;&) {
		303	my $id = "$UNIQ." . $ID++;
		304	my $port = "$NODE#$id";
		305
		306	if (@_) {
		307	rcv $port, shift;
		308	} else {
		309	$PORT{$id} = sub { }; # nop
		310	}
		311
		312	$port
158	}	313	}
159		314
160	=item $portid = create_miniport { }	315	=item reg $port, $name
161		316
162	Creates a "mini port", that is, a port without much #TODO	317	=item reg $name
163		318
164	=cut	319	Registers the given port (or C<$SELF><<< if missing) under the name
		320	C<$name>. If the name already exists it is replaced.
165		321
166	sub create_miniport(&) {	322	A port can only be registered under one well known name.
167	my $cb = shift;
168	my $id = "$AnyEvent::MP::Base::UNIQ." . ++$AnyEvent::MP::Base::ID;
169		323
170	$AnyEvent::MP::Base::PORT{$id} = sub {	324	A port automatically becomes unregistered when it is killed.
171	&$cb
172	and delete $AnyEvent::MP::Base::PORT{$id};
173	};
174		325
175	"$NODE#$id"	326	=cut
		327
		328	sub reg(@) {
		329	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
		330
		331	$REG{$_[0]} = $port;
176	}	332	}
177		333
178	package AnyEvent::MP::Port;	334	=item rcv $port, $callback->(@msg)
179		335
180	=back	336	Replaces the callback on the specified miniport (after converting it to
		337	one if required).
181		338
182	=head1 METHODS FOR PORT OBJECTS	339	=item rcv $port, tagstring => $callback->(@msg), ...
183		340
184	=over 4	341	=item rcv $port, $smartmatch => $callback->(@msg), ...
185		342
186	=item "$port"
187
188	A port object stringifies to its port ID, so can be used directly for
189	C<snd> operations.
190
191	=cut
192
193	use overload
194	'""' => sub { $_[0]{id} },
195	fallback => 1;
196
197	=item $port->rcv (type => $callback->($port, @msg))
198
199	=item $port->rcv ($smartmatch => $callback->($port, @msg))
200
201	=item $port->rcv ([$smartmatch...] => $callback->($port, @msg))	343	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
202		344
203	Register a callback on the given port.	345	Register callbacks to be called on matching messages on the given full
		346	port (after converting it to one if required) and return the port.
204		347
205	The callback has to return a true value when its work is done, after	348	The callback has to return a true value when its work is done, after
206	which is will be removed, or a false value in which case it will stay	349	which is will be removed, or a false value in which case it will stay
207	registered.	350	registered.
208		351
		352	The global C<$SELF> (exported by this module) contains C<$port> while
		353	executing the callback.
		354
		355	Runtime errors during callback execution will result in the port being
		356	C<kil>ed.
		357
209	If the match is an array reference, then it will be matched against the	358	If the match is an array reference, then it will be matched against the
210	first elements of the message, otherwise only the first element is being	359	first elements of the message, otherwise only the first element is being
211	matched.	360	matched.
212		361
213	Any element in the match that is specified as C<_any_> (a function	362	Any element in the match that is specified as C<_any_> (a function
…		…
215		364
216	While not required, it is highly recommended that the first matching	365	While not required, it is highly recommended that the first matching
217	element is a string identifying the message. The one-string-only match is	366	element is a string identifying the message. The one-string-only match is
218	also the most efficient match (by far).	367	also the most efficient match (by far).
219		368
		369	Example: create a port and bind receivers on it in one go.
		370
		371	my $port = rcv port,
		372	msg1 => sub { ...; 0 },
		373	msg2 => sub { ...; 0 },
		374	;
		375
		376	Example: create a port, bind receivers and send it in a message elsewhere
		377	in one go:
		378
		379	snd $otherport, reply =>
		380	rcv port,
		381	msg1 => sub { ...; 0 },
		382	...
		383	;
		384
220	=cut	385	=cut
221		386
222	sub rcv($@) {	387	sub rcv($@) {
223	my ($self, $match, $cb) = @_;	388	my $port = shift;
		389	my ($noderef, $portid) = split /#/, $port, 2;
224		390
225	if (!ref $match) {	391	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
226	push @{ $self->{rc0}{$match} }, [$cb];	392	or Carp::croak "$port: rcv can only be called on local ports, caught";
227	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	393
228	my ($type, @match) = @$match;	394	if (@_ == 1) {
229	@match	395	my $cb = shift;
230	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	396	delete $PORT_DATA{$portid};
231	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	397	$PORT{$portid} = sub {
		398	local $SELF = $port;
		399	eval {
		400	&$cb
		401	and kil $port;
		402	};
		403	_self_die if $@;
		404	};
232	} else {	405	} else {
		406	my $self = $PORT_DATA{$portid} \|\|= do {
		407	my $self = bless {
		408	id => $port,
		409	}, "AnyEvent::MP::Port";
		410
		411	$PORT{$portid} = sub {
		412	local $SELF = $port;
		413
		414	eval {
		415	for (@{ $self->{rc0}{$_[0]} }) {
		416	$_ && &{$_->[0]}
		417	&& undef $_;
		418	}
		419
		420	for (@{ $self->{rcv}{$_[0]} }) {
		421	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
		422	&& &{$_->[0]}
		423	&& undef $_;
		424	}
		425
		426	for (@{ $self->{any} }) {
		427	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
		428	&& &{$_->[0]}
		429	&& undef $_;
		430	}
		431	};
		432	_self_die if $@;
		433	};
		434
		435	$self
		436	};
		437
		438	"AnyEvent::MP::Port" eq ref $self
		439	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		440
		441	while (@_) {
		442	my ($match, $cb) = splice @_, 0, 2;
		443
		444	if (!ref $match) {
		445	push @{ $self->{rc0}{$match} }, [$cb];
		446	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
		447	my ($type, @match) = @$match;
		448	@match
		449	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
		450	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
		451	} else {
233	push @{ $self->{any} }, [$cb, $match];	452	push @{ $self->{any} }, [$cb, $match];
		453	}
		454	}
		455	}
		456
		457	$port
		458	}
		459
		460	=item $closure = psub { BLOCK }
		461
		462	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		463	closure is executed, sets up the environment in the same way as in C<rcv>
		464	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		465
		466	This is useful when you register callbacks from C<rcv> callbacks:
		467
		468	rcv delayed_reply => sub {
		469	my ($delay, @reply) = @_;
		470	my $timer = AE::timer $delay, 0, psub {
		471	snd @reply, $SELF;
		472	};
		473	};
		474
		475	=cut
		476
		477	sub psub(&) {
		478	my $cb = shift;
		479
		480	my $port = $SELF
		481	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		482
		483	sub {
		484	local $SELF = $port;
		485
		486	if (wantarray) {
		487	my @res = eval { &$cb };
		488	_self_die if $@;
		489	@res
		490	} else {
		491	my $res = eval { &$cb };
		492	_self_die if $@;
		493	$res
		494	}
234	}	495	}
235	}	496	}
236		497
237	=item $port->register ($name)	498	=item $guard = mon $port, $cb->(@reason)
238		499
239	Registers the given port under the well known name C<$name>. If the name	500	=item $guard = mon $port, $rcvport
240	already exists it is replaced.
241		501
242	A port can only be registered under one well known name.	502	=item $guard = mon $port
243		503
244	=cut	504	=item $guard = mon $port, $rcvport, @msg
245		505
246	sub register {	506	Monitor the given port and do something when the port is killed or
247	my ($self, $name) = @_;	507	messages to it were lost, and optionally return a guard that can be used
		508	to stop monitoring again.
248		509
249	$self->{wkname} = $name;	510	C<mon> effectively guarantees that, in the absence of hardware failures,
250	$AnyEvent::MP::Base::WKP{$name} = "$self";	511	that after starting the monitor, either all messages sent to the port
		512	will arrive, or the monitoring action will be invoked after possible
		513	message loss has been detected. No messages will be lost "in between"
		514	(after the first lost message no further messages will be received by the
		515	port). After the monitoring action was invoked, further messages might get
		516	delivered again.
		517
		518	In the first form (callback), the callback is simply called with any
		519	number of C<@reason> elements (no @reason means that the port was deleted
		520	"normally"). Note also that I<< the callback B<must> never die >>, so use
		521	C<eval> if unsure.
		522
		523	In the second form (another port given), the other port (C<$rcvport)
		524	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		525	"normal" kils nothing happens, while under all other conditions, the other
		526	port is killed with the same reason.
		527
		528	The third form (kill self) is the same as the second form, except that
		529	C<$rvport> defaults to C<$SELF>.
		530
		531	In the last form (message), a message of the form C<@msg, @reason> will be
		532	C<snd>.
		533
		534	As a rule of thumb, monitoring requests should always monitor a port from
		535	a local port (or callback). The reason is that kill messages might get
		536	lost, just like any other message. Another less obvious reason is that
		537	even monitoring requests can get lost (for exmaple, when the connection
		538	to the other node goes down permanently). When monitoring a port locally
		539	these problems do not exist.
		540
		541	Example: call a given callback when C<$port> is killed.
		542
		543	mon $port, sub { warn "port died because of <@_>\n" };
		544
		545	Example: kill ourselves when C<$port> is killed abnormally.
		546
		547	mon $port;
		548
		549	Example: send us a restart message when another C<$port> is killed.
		550
		551	mon $port, $self => "restart";
		552
		553	=cut
		554
		555	sub mon {
		556	my ($noderef, $port) = split /#/, shift, 2;
		557
		558	my $node = $NODE{$noderef} \|\| add_node $noderef;
		559
		560	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		561
		562	unless (ref $cb) {
		563	if (@_) {
		564	# send a kill info message
		565	my (@msg) = ($cb, @_);
		566	$cb = sub { snd @msg, @_ };
		567	} else {
		568	# simply kill other port
		569	my $port = $cb;
		570	$cb = sub { kil $port, @_ if @_ };
		571	}
		572	}
		573
		574	$node->monitor ($port, $cb);
		575
		576	defined wantarray
		577	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
251	}	578	}
252		579
253	=item $port->destroy	580	=item $guard = mon_guard $port, $ref, $ref...
254		581
255	Explicitly destroy/remove/nuke/vaporise the port.	582	Monitors the given C<$port> and keeps the passed references. When the port
		583	is killed, the references will be freed.
256		584
257	Ports are normally kept alive by there mere existance alone, and need to	585	Optionally returns a guard that will stop the monitoring.
258	be destroyed explicitly.
259		586
260	=cut	587	This function is useful when you create e.g. timers or other watchers and
		588	want to free them when the port gets killed:
261		589
262	sub destroy {	590	$port->rcv (start => sub {
263	my ($self) = @_;	591	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		592	undef $timer if 0.9 < rand;
		593	});
		594	});
264		595
265	delete $AnyEvent::MP::Base::WKP{ $self->{wkname} };	596	=cut
266		597
267	delete $AnyEvent::MP::Base::PORT{$_}	598	sub mon_guard {
268	for @{ $self->{names} };	599	my ($port, @refs) = @_;
		600
		601	#TODO: mon-less form?
		602
		603	mon $port, sub { 0 && @refs }
269	}	604	}
270		605
271	=back	606	=item kil $port[, @reason]
272		607
273	=head1 FUNCTIONS FOR NODES	608	Kill the specified port with the given C<@reason>.
274		609
275	=over 4	610	If no C<@reason> is specified, then the port is killed "normally" (linked
		611	ports will not be kileld, or even notified).
276		612
277	=item mon $noderef, $callback->($noderef, $status, $)	613	Otherwise, linked ports get killed with the same reason (second form of
		614	C<mon>, see below).
278		615
279	Monitors the given noderef.	616	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		617	will be reported as reason C<< die => $@ >>.
280		618
281	=item become_public endpoint...	619	Transport/communication errors are reported as C<< transport_error =>
		620	$message >>.
282		621
283	Tells the node to become a public node, i.e. reachable from other nodes.
284
285	If no arguments are given, or the first argument is C<undef>, then
286	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the
287	local nodename resolves to.
288
289	Otherwise the first argument must be an array-reference with transport
290	endpoints ("ip:port", "hostname:port") or port numbers (in which case the
291	local nodename is used as hostname). The endpoints are all resolved and
292	will become the node reference.
293
294	=cut	622	=cut
		623
		624	=item $port = spawn $node, $initfunc[, @initdata]
		625
		626	Creates a port on the node C<$node> (which can also be a port ID, in which
		627	case it's the node where that port resides).
		628
		629	The port ID of the newly created port is return immediately, and it is
		630	permissible to immediately start sending messages or monitor the port.
		631
		632	After the port has been created, the init function is
		633	called. This function must be a fully-qualified function name
		634	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		635	program, use C<::name>.
		636
		637	If the function doesn't exist, then the node tries to C<require>
		638	the package, then the package above the package and so on (e.g.
		639	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		640	exists or it runs out of package names.
		641
		642	The init function is then called with the newly-created port as context
		643	object (C<$SELF>) and the C<@initdata> values as arguments.
		644
		645	A common idiom is to pass your own port, monitor the spawned port, and
		646	in the init function, monitor the original port. This two-way monitoring
		647	ensures that both ports get cleaned up when there is a problem.
		648
		649	Example: spawn a chat server port on C<$othernode>.
		650
		651	# this node, executed from within a port context:
		652	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		653	mon $server;
		654
		655	# init function on C<$othernode>
		656	sub connect {
		657	my ($srcport) = @_;
		658
		659	mon $srcport;
		660
		661	rcv $SELF, sub {
		662	...
		663	};
		664	}
		665
		666	=cut
		667
		668	sub _spawn {
		669	my $port = shift;
		670	my $init = shift;
		671
		672	local $SELF = "$NODE#$port";
		673	eval {
		674	&{ load_func $init }
		675	};
		676	_self_die if $@;
		677	}
		678
		679	sub spawn(@) {
		680	my ($noderef, undef) = split /#/, shift, 2;
		681
		682	my $id = "$RUNIQ." . $ID++;
		683
		684	$_[0] =~ /::/
		685	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		686
		687	($NODE{$noderef} \|\| add_node $noderef)
		688	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		689
		690	"$noderef#$id"
		691	}
295		692
296	=back	693	=back
297		694
298	=head1 NODE MESSAGES	695	=head1 NODE MESSAGES
299		696
300	Nodes understand the following messages sent to them. Many of them take	697	Nodes understand the following messages sent to them. Many of them take
301	arguments called C<@reply>, which will simply be used to compose a reply	698	arguments called C<@reply>, which will simply be used to compose a reply
302	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	699	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
303	the remaining arguments are simply the message data.	700	the remaining arguments are simply the message data.
304		701
		702	While other messages exist, they are not public and subject to change.
		703
305	=over 4	704	=over 4
306		705
307	=cut	706	=cut
308		707
309	=item wkp => $name, @reply	708	=item lookup => $name, @reply
310		709
311	Replies with the port ID of the specified well-known port, or C<undef>.	710	Replies with the port ID of the specified well-known port, or C<undef>.
312		711
313	=item devnull => ...	712	=item devnull => ...
314		713
…		…
337	snd $NODE, time => $myport, timereply => 1, 2;	736	snd $NODE, time => $myport, timereply => 1, 2;
338	# => snd $myport, timereply => 1, 2, <time>	737	# => snd $myport, timereply => 1, 2, <time>
339		738
340	=back	739	=back
341		740
		741	=head1 AnyEvent::MP vs. Distributed Erlang
		742
		743	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		744	== aemp node, Erlang process == aemp port), so many of the documents and
		745	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		746	sample:
		747
		748	http://www.Erlang.se/doc/programming_rules.shtml
		749	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		750	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		751	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		752
		753	Despite the similarities, there are also some important differences:
		754
		755	=over 4
		756
		757	=item * Node references contain the recipe on how to contact them.
		758
		759	Erlang relies on special naming and DNS to work everywhere in the
		760	same way. AEMP relies on each node knowing it's own address(es), with
		761	convenience functionality.
		762
		763	This means that AEMP requires a less tightly controlled environment at the
		764	cost of longer node references and a slightly higher management overhead.
		765
		766	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		767
		768	Erlang uses processes that selctively receive messages, and therefore
		769	needs a queue. AEMP is event based, queuing messages would serve no useful
		770	purpose.
		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. AEMP
		777	sends are immediate, connection establishment is handled in the
		778	background.
		779
		780	=item * Erlang can silently lose messages, AEMP cannot.
		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 possible that a node that restarts reuses a process
		803	ID known to other nodes for a completely different process, causing
		804	messages 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
342	=head1 SEE ALSO	850	=head1 SEE ALSO
343		851
344	L<AnyEvent>.	852	L<AnyEvent>.
345		853
346	=head1 AUTHOR	854	=head1 AUTHOR

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Revision 1.42 by root, Sun Aug 9 00:41:49 2009 UTC