[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 1.48 by root, Thu Aug 13 02:59:42 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
		27	# creating/using miniports
		28	my $miniport = port { my @msg = @_; 0 };
		29
		30	# creating/using full ports
		31	my $port = port;
14	rcv $port, smartmatch => $cb->($port, @msg);	32	rcv $port, smartmatch => $cb->(@msg);
15
16	# examples:
17	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	33	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
18	rcv $port1, pong => sub { warn "pong received\n" };	34	rcv $port, pong => sub { warn "pong received\n"; 0 };
19	snd $port2, ping => $port1;
20		35
21	# more, smarter, matches (_any_ is exported by this module)	36	# more, smarter, matches (_any_ is exported by this module)
22	rcv $port, [child_died => $pid] => sub { ...	37	rcv $port, [child_died => $pid] => sub { ...
23	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	38	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
24		39
		40	# create a port on another node
		41	my $port = spawn $node, $initfunc, @initdata;
		42
		43	# monitoring
		44	mon $port, $cb->(@msg) # callback is invoked on death
		45	mon $port, $otherport # kill otherport on abnormal death
		46	mon $port, $otherport, @msg # send message on death
		47
		48	=head1 CURRENT STATUS
		49
		50	AnyEvent::MP - stable API, should work
		51	AnyEvent::MP::Intro - outdated
		52	AnyEvent::MP::Kernel - WIP
		53	AnyEvent::MP::Transport - mostly stable
		54
		55	stay tuned.
		56
25	=head1 DESCRIPTION	57	=head1 DESCRIPTION
26		58
27	This module (-family) implements a simple message passing framework.	59	This module (-family) implements a simple message passing framework.
28		60
29	Despite its simplicity, you can securely message other processes running	61	Despite its simplicity, you can securely message other processes running
30	on the same or other hosts.	62	on the same or other hosts.
31		63
		64	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		65	manual page.
		66
32	At the moment, this module family is severly brokena nd underdocumented,	67	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 -	68	so do not use. This was uploaded mainly to reserve the CPAN namespace -
34	stay tuned!	69	stay tuned!
35		70
36	=head1 CONCEPTS	71	=head1 CONCEPTS
37		72
38	=over 4	73	=over 4
39		74
40	=item port	75	=item port
41		76
42	A port is something you can send messages to with the C<snd> function, and	77	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	78
44	messages they match, messages will not be queued.	79	Some ports allow you to register C<rcv> handlers that can match specific
		80	messages. All C<rcv> handlers will receive messages they match, messages
		81	will not be queued.
45		82
46	=item port id - C<noderef#portname>	83	=item port id - C<noderef#portname>
47		84
48	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	85	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).	86	separator, and a port name (a printable string of unspecified format). An
		87	exception is the the node port, whose ID is identical to its node
		88	reference.
50		89
51	=item node	90	=item node
52		91
53	A node is a single process containing at least one port - the node	92	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,	93	port. You can send messages to node ports to find existing ports or to
55	among other things.	94	create new ports, among other things.
56		95
57	Initially, nodes are either private (single-process only) or hidden	96	Nodes are either private (single-process only), slaves (connected to a
58	(connected to a master node only). Only when they epxlicitly "become	97	master node only) or public nodes (connectable from unrelated nodes).
59	public" can you send them messages from unrelated other nodes.
60		98
61	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	99	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
62		100
63	A noderef is a string that either uniquely identifies a given node (for	101	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	102	private and slave nodes), or contains a recipe on how to reach a given
65	node (for public nodes).	103	node (for public nodes).
66		104
		105	This recipe is simply a comma-separated list of C<address:port> pairs (for
		106	TCP/IP, other protocols might look different).
		107
		108	Node references come in two flavours: resolved (containing only numerical
		109	addresses) or unresolved (where hostnames are used instead of addresses).
		110
		111	Before using an unresolved node reference in a message you first have to
		112	resolve it.
		113
67	=back	114	=back
68		115
69	=head1 VARIABLES/FUNCTIONS	116	=head1 VARIABLES/FUNCTIONS
70		117
71	=over 4	118	=over 4
72		119
73	=cut	120	=cut
74		121
75	package AnyEvent::MP;	122	package AnyEvent::MP;
76		123
77	use AnyEvent::MP::Base;	124	use AnyEvent::MP::Kernel;
78		125
79	use common::sense;	126	use common::sense;
80		127
81	use Carp ();	128	use Carp ();
82		129
83	use AE ();	130	use AE ();
84		131
85	use base "Exporter";	132	use base "Exporter";
86		133
87	our $VERSION = '0.02';	134	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		135
88	our @EXPORT = qw(	136	our @EXPORT = qw(
89	NODE $NODE $PORT snd rcv _any_	137	NODE $NODE *SELF node_of _any_
90	create_port create_port_on	138	resolve_node initialise_node
91	become_slave become_public	139	snd rcv mon kil reg psub spawn
		140	port
92	);	141	);
93		142
		143	our $SELF;
		144
		145	sub _self_die() {
		146	my $msg = $@;
		147	$msg =~ s/\n+$// unless ref $msg;
		148	kil $SELF, die => $msg;
		149	}
		150
94	=item NODE / $NODE	151	=item $thisnode = NODE / $NODE
95		152
96	The C<NODE ()> function and the C<$NODE> variable contain the noderef of	153	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	154	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.	155	to C<become_public> or C<become_slave>, after which all local port
		156	identifiers become invalid.
99		157
		158	=item $noderef = node_of $port
		159
		160	Extracts and returns the noderef from a portid or a noderef.
		161
		162	=item initialise_node $noderef, $seednode, $seednode...
		163
		164	=item initialise_node "slave/", $master, $master...
		165
		166	Before a node can talk to other nodes on the network it has to initialise
		167	itself - the minimum a node needs to know is it's own name, and optionally
		168	it should know the noderefs of some other nodes in the network.
		169
		170	This function initialises a node - it must be called exactly once (or
		171	never) before calling other AnyEvent::MP functions.
		172
		173	All arguments are noderefs, which can be either resolved or unresolved.
		174
		175	There are two types of networked nodes, public nodes and slave nodes:
		176
		177	=over 4
		178
		179	=item public nodes
		180
		181	For public nodes, C<$noderef> must either be a (possibly unresolved)
		182	noderef, in which case it will be resolved, or C<undef> (or missing), in
		183	which case the noderef will be guessed.
		184
		185	Afterwards, the node will bind itself on all endpoints and try to connect
		186	to all additional C<$seednodes> that are specified. Seednodes are optional
		187	and can be used to quickly bootstrap the node into an existing network.
		188
		189	=item slave nodes
		190
		191	When the C<$noderef> is the special string C<slave/>, then the node will
		192	become a slave node. Slave nodes cannot be contacted from outside and will
		193	route most of their traffic to the master node that they attach to.
		194
		195	At least one additional noderef is required: The node will try to connect
		196	to all of them and will become a slave attached to the first node it can
		197	successfully connect to.
		198
		199	=back
		200
		201	This function will block until all nodes have been resolved and, for slave
		202	nodes, until it has successfully established a connection to a master
		203	server.
		204
		205	Example: become a public node listening on the default node.
		206
		207	initialise_node;
		208
		209	Example: become a public node, and try to contact some well-known master
		210	servers to become part of the network.
		211
		212	initialise_node undef, "master1", "master2";
		213
		214	Example: become a public node listening on port C<4041>.
		215
		216	initialise_node 4041;
		217
		218	Example: become a public node, only visible on localhost port 4044.
		219
		220	initialise_node "locahost:4044";
		221
		222	Example: become a slave node to any of the specified master servers.
		223
		224	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		225
		226	=item $cv = resolve_node $noderef
		227
		228	Takes an unresolved node reference that may contain hostnames and
		229	abbreviated IDs, resolves all of them and returns a resolved node
		230	reference.
		231
		232	In addition to C<address:port> pairs allowed in resolved noderefs, the
		233	following forms are supported:
		234
		235	=over 4
		236
		237	=item the empty string
		238
		239	An empty-string component gets resolved as if the default port (4040) was
		240	specified.
		241
		242	=item naked port numbers (e.g. C<1234>)
		243
		244	These are resolved by prepending the local nodename and a colon, to be
		245	further resolved.
		246
		247	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		248
		249	These are resolved by using AnyEvent::DNS to resolve them, optionally
		250	looking up SRV records for the C<aemp=4040> port, if no port was
		251	specified.
		252
		253	=back
		254
		255	=item $SELF
		256
		257	Contains the current port id while executing C<rcv> callbacks or C<psub>
		258	blocks.
		259
		260	=item SELF, %SELF, @SELF...
		261
		262	Due to some quirks in how perl exports variables, it is impossible to
		263	just export C<$SELF>, all the symbols called C<SELF> are exported by this
		264	module, but only C<$SELF> is currently used.
		265
100	=item snd $portid, type => @data	266	=item snd $port, type => @data
101		267
102	=item snd $portid, @msg	268	=item snd $port, @msg
103		269
104	Send the given message to the given port ID, which can identify either	270	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	271	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 :).	272	stringifies a sa port ID (such as a port object :).
107		273
…		…
117	JSON is used, then only strings, numbers and arrays and hashes consisting	283	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	284	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	285	that Storable can serialise and deserialise is allowed, and for the local
120	node, anything can be passed.	286	node, anything can be passed.
121		287
122	=item $local_port = create_port	288	=item $local_port = port
123		289
124	Create a new local port object. See the next section for allowed methods.	290	Create a new local port object that can be used either as a pattern
		291	matching port ("full port") or a single-callback port ("miniport"),
		292	depending on how C<rcv> callbacks are bound to the object.
125		293
126	=cut	294	=item $port = port { my @msg = @_; $finished }
127		295
128	sub create_port {	296	Creates a "miniport", that is, a very lightweight port without any pattern
129	my $id = "$AnyEvent::MP::Base::UNIQ." . ++$AnyEvent::MP::Base::ID;	297	matching behind it, and returns its ID. Semantically the same as creating
		298	a port and calling C<rcv $port, $callback> on it.
130		299
131	my $self = bless {	300	The block will be called for every message received on the port. When the
132	id => "$NODE#$id",	301	callback returns a true value its job is considered "done" and the port
133	names => [$id],	302	will be destroyed. Otherwise it will stay alive.
134	}, "AnyEvent::MP::Port";
135		303
136	$AnyEvent::MP::Base::PORT{$id} = sub {	304	The message will be passed as-is, no extra argument (i.e. no port id) will
137	unshift @_, $self;	305	be passed to the callback.
138		306
139	for (@{ $self->{rc0}{$_[1]} }) {	307	If you need the local port id in the callback, this works nicely:
140	$_ && &{$_->[0]}
141	&& undef $_;
142	}
143		308
144	for (@{ $self->{rcv}{$_[1]} }) {	309	my $port; $port = port {
145	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	310	snd $otherport, reply => $port;
146	&& &{$_->[0]}
147	&& undef $_;
148	}
149
150	for (@{ $self->{any} }) {
151	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
152	&& &{$_->[0]}
153	&& undef $_;
154	}
155	};	311	};
156		312
157	$self	313	=cut
		314
		315	sub rcv($@);
		316
		317	sub port(;&) {
		318	my $id = "$UNIQ." . $ID++;
		319	my $port = "$NODE#$id";
		320
		321	if (@_) {
		322	rcv $port, shift;
		323	} else {
		324	$PORT{$id} = sub { }; # nop
		325	}
		326
		327	$port
158	}	328	}
159		329
160	package AnyEvent::MP::Port;	330	=item reg $port, $name
161		331
162	=back	332	=item reg $name
163		333
164	=head1 METHODS FOR PORT OBJECTS	334	Registers the given port (or C<$SELF><<< if missing) under the name
		335	C<$name>. If the name already exists it is replaced.
165		336
166	=over 4	337	A port can only be registered under one well known name.
167		338
168	=item "$port"	339	A port automatically becomes unregistered when it is killed.
169		340
170	A port object stringifies to its port ID, so can be used directly for
171	C<snd> operations.
172
173	=cut	341	=cut
174		342
175	use overload	343	sub reg(@) {
176	'""' => sub { $_[0]{id} },	344	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
177	fallback => 1;
178		345
179	=item $port->rcv (type => $callback->($port, @msg))	346	$REG{$_[0]} = $port;
		347	}
180		348
181	=item $port->rcv ($smartmatch => $callback->($port, @msg))	349	=item rcv $port, $callback->(@msg)
182		350
		351	Replaces the callback on the specified miniport (after converting it to
		352	one if required).
		353
		354	=item rcv $port, tagstring => $callback->(@msg), ...
		355
		356	=item rcv $port, $smartmatch => $callback->(@msg), ...
		357
183	=item $port->rcv ([$smartmatch...] => $callback->($port, @msg))	358	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
184		359
185	Register a callback on the given port.	360	Register callbacks to be called on matching messages on the given full
		361	port (after converting it to one if required) and return the port.
186		362
187	The callback has to return a true value when its work is done, after	363	The callback has to return a true value when its work is done, after
188	which is will be removed, or a false value in which case it will stay	364	which is will be removed, or a false value in which case it will stay
189	registered.	365	registered.
190		366
		367	The global C<$SELF> (exported by this module) contains C<$port> while
		368	executing the callback.
		369
		370	Runtime errors during callback execution will result in the port being
		371	C<kil>ed.
		372
191	If the match is an array reference, then it will be matched against the	373	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	374	first elements of the message, otherwise only the first element is being
193	matched.	375	matched.
194		376
195	Any element in the match that is specified as C<_any_> (a function	377	Any element in the match that is specified as C<_any_> (a function
…		…
197		379
198	While not required, it is highly recommended that the first matching	380	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	381	element is a string identifying the message. The one-string-only match is
200	also the most efficient match (by far).	382	also the most efficient match (by far).
201		383
		384	Example: create a port and bind receivers on it in one go.
		385
		386	my $port = rcv port,
		387	msg1 => sub { ...; 0 },
		388	msg2 => sub { ...; 0 },
		389	;
		390
		391	Example: create a port, bind receivers and send it in a message elsewhere
		392	in one go:
		393
		394	snd $otherport, reply =>
		395	rcv port,
		396	msg1 => sub { ...; 0 },
		397	...
		398	;
		399
202	=cut	400	=cut
203		401
204	sub rcv($@) {	402	sub rcv($@) {
205	my ($self, $match, $cb) = @_;	403	my $port = shift;
		404	my ($noderef, $portid) = split /#/, $port, 2;
206		405
207	if (!ref $match) {	406	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
208	push @{ $self->{rc0}{$match} }, [$cb];	407	or Carp::croak "$port: rcv can only be called on local ports, caught";
209	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	408
210	my ($type, @match) = @$match;	409	if (@_ == 1) {
211	@match	410	my $cb = shift;
212	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	411	delete $PORT_DATA{$portid};
213	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	412	$PORT{$portid} = sub {
		413	local $SELF = $port;
		414	eval {
		415	&$cb
		416	and kil $port;
		417	};
		418	_self_die if $@;
		419	};
214	} else {	420	} else {
		421	my $self = $PORT_DATA{$portid} \|\|= do {
		422	my $self = bless {
		423	id => $port,
		424	}, "AnyEvent::MP::Port";
		425
		426	$PORT{$portid} = sub {
		427	local $SELF = $port;
		428
		429	eval {
		430	for (@{ $self->{rc0}{$_[0]} }) {
		431	$_ && &{$_->[0]}
		432	&& undef $_;
		433	}
		434
		435	for (@{ $self->{rcv}{$_[0]} }) {
		436	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
		437	&& &{$_->[0]}
		438	&& undef $_;
		439	}
		440
		441	for (@{ $self->{any} }) {
		442	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
		443	&& &{$_->[0]}
		444	&& undef $_;
		445	}
		446	};
		447	_self_die if $@;
		448	};
		449
		450	$self
		451	};
		452
		453	"AnyEvent::MP::Port" eq ref $self
		454	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		455
		456	while (@_) {
		457	my ($match, $cb) = splice @_, 0, 2;
		458
		459	if (!ref $match) {
		460	push @{ $self->{rc0}{$match} }, [$cb];
		461	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
		462	my ($type, @match) = @$match;
		463	@match
		464	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
		465	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
		466	} else {
215	push @{ $self->{any} }, [$cb, $match];	467	push @{ $self->{any} }, [$cb, $match];
		468	}
		469	}
		470	}
		471
		472	$port
		473	}
		474
		475	=item $closure = psub { BLOCK }
		476
		477	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		478	closure is executed, sets up the environment in the same way as in C<rcv>
		479	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		480
		481	This is useful when you register callbacks from C<rcv> callbacks:
		482
		483	rcv delayed_reply => sub {
		484	my ($delay, @reply) = @_;
		485	my $timer = AE::timer $delay, 0, psub {
		486	snd @reply, $SELF;
		487	};
		488	};
		489
		490	=cut
		491
		492	sub psub(&) {
		493	my $cb = shift;
		494
		495	my $port = $SELF
		496	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		497
		498	sub {
		499	local $SELF = $port;
		500
		501	if (wantarray) {
		502	my @res = eval { &$cb };
		503	_self_die if $@;
		504	@res
		505	} else {
		506	my $res = eval { &$cb };
		507	_self_die if $@;
		508	$res
		509	}
216	}	510	}
217	}	511	}
218		512
219	=item $port->register ($name)	513	=item $guard = mon $port, $cb->(@reason)
220		514
221	Registers the given port under the well known name C<$name>. If the name	515	=item $guard = mon $port, $rcvport
222	already exists it is replaced.
223		516
224	A port can only be registered under one well known name.	517	=item $guard = mon $port
225		518
226	=cut	519	=item $guard = mon $port, $rcvport, @msg
227		520
228	sub register {	521	Monitor the given port and do something when the port is killed or
229	my ($self, $name) = @_;	522	messages to it were lost, and optionally return a guard that can be used
		523	to stop monitoring again.
230		524
231	$self->{wkname} = $name;	525	C<mon> effectively guarantees that, in the absence of hardware failures,
232	$AnyEvent::MP::Base::WKP{$name} = "$self";	526	that after starting the monitor, either all messages sent to the port
		527	will arrive, or the monitoring action will be invoked after possible
		528	message loss has been detected. No messages will be lost "in between"
		529	(after the first lost message no further messages will be received by the
		530	port). After the monitoring action was invoked, further messages might get
		531	delivered again.
		532
		533	In the first form (callback), the callback is simply called with any
		534	number of C<@reason> elements (no @reason means that the port was deleted
		535	"normally"). Note also that I<< the callback B<must> never die >>, so use
		536	C<eval> if unsure.
		537
		538	In the second form (another port given), the other port (C<$rcvport>)
		539	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		540	"normal" kils nothing happens, while under all other conditions, the other
		541	port is killed with the same reason.
		542
		543	The third form (kill self) is the same as the second form, except that
		544	C<$rvport> defaults to C<$SELF>.
		545
		546	In the last form (message), a message of the form C<@msg, @reason> will be
		547	C<snd>.
		548
		549	As a rule of thumb, monitoring requests should always monitor a port from
		550	a local port (or callback). The reason is that kill messages might get
		551	lost, just like any other message. Another less obvious reason is that
		552	even monitoring requests can get lost (for exmaple, when the connection
		553	to the other node goes down permanently). When monitoring a port locally
		554	these problems do not exist.
		555
		556	Example: call a given callback when C<$port> is killed.
		557
		558	mon $port, sub { warn "port died because of <@_>\n" };
		559
		560	Example: kill ourselves when C<$port> is killed abnormally.
		561
		562	mon $port;
		563
		564	Example: send us a restart message when another C<$port> is killed.
		565
		566	mon $port, $self => "restart";
		567
		568	=cut
		569
		570	sub mon {
		571	my ($noderef, $port) = split /#/, shift, 2;
		572
		573	my $node = $NODE{$noderef} \|\| add_node $noderef;
		574
		575	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		576
		577	unless (ref $cb) {
		578	if (@_) {
		579	# send a kill info message
		580	my (@msg) = ($cb, @_);
		581	$cb = sub { snd @msg, @_ };
		582	} else {
		583	# simply kill other port
		584	my $port = $cb;
		585	$cb = sub { kil $port, @_ if @_ };
		586	}
		587	}
		588
		589	$node->monitor ($port, $cb);
		590
		591	defined wantarray
		592	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
233	}	593	}
234		594
235	=item $port->destroy	595	=item $guard = mon_guard $port, $ref, $ref...
236		596
237	Explicitly destroy/remove/nuke/vaporise the port.	597	Monitors the given C<$port> and keeps the passed references. When the port
		598	is killed, the references will be freed.
238		599
239	Ports are normally kept alive by there mere existance alone, and need to	600	Optionally returns a guard that will stop the monitoring.
240	be destroyed explicitly.
241		601
242	=cut	602	This function is useful when you create e.g. timers or other watchers and
		603	want to free them when the port gets killed:
243		604
244	sub destroy {	605	$port->rcv (start => sub {
245	my ($self) = @_;	606	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		607	undef $timer if 0.9 < rand;
		608	});
		609	});
246		610
247	delete $AnyEvent::MP::Base::WKP{ $self->{wkname} };	611	=cut
248		612
249	delete $AnyEvent::MP::Base::PORT{$_}	613	sub mon_guard {
250	for @{ $self->{names} };	614	my ($port, @refs) = @_;
		615
		616	#TODO: mon-less form?
		617
		618	mon $port, sub { 0 && @refs }
251	}	619	}
252		620
253	=back	621	=item kil $port[, @reason]
254		622
255	=head1 FUNCTIONS FOR NODES	623	Kill the specified port with the given C<@reason>.
256		624
257	=over 4	625	If no C<@reason> is specified, then the port is killed "normally" (linked
		626	ports will not be kileld, or even notified).
258		627
259	=item mon $noderef, $callback->($noderef, $status, $)	628	Otherwise, linked ports get killed with the same reason (second form of
		629	C<mon>, see below).
260		630
261	Monitors the given noderef.	631	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		632	will be reported as reason C<< die => $@ >>.
262		633
263	=item become_public endpoint...	634	Transport/communication errors are reported as C<< transport_error =>
		635	$message >>.
264		636
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	637	=cut
		638
		639	=item $port = spawn $node, $initfunc[, @initdata]
		640
		641	Creates a port on the node C<$node> (which can also be a port ID, in which
		642	case it's the node where that port resides).
		643
		644	The port ID of the newly created port is return immediately, and it is
		645	permissible to immediately start sending messages or monitor the port.
		646
		647	After the port has been created, the init function is
		648	called. This function must be a fully-qualified function name
		649	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		650	program, use C<::name>.
		651
		652	If the function doesn't exist, then the node tries to C<require>
		653	the package, then the package above the package and so on (e.g.
		654	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		655	exists or it runs out of package names.
		656
		657	The init function is then called with the newly-created port as context
		658	object (C<$SELF>) and the C<@initdata> values as arguments.
		659
		660	A common idiom is to pass your own port, monitor the spawned port, and
		661	in the init function, monitor the original port. This two-way monitoring
		662	ensures that both ports get cleaned up when there is a problem.
		663
		664	Example: spawn a chat server port on C<$othernode>.
		665
		666	# this node, executed from within a port context:
		667	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		668	mon $server;
		669
		670	# init function on C<$othernode>
		671	sub connect {
		672	my ($srcport) = @_;
		673
		674	mon $srcport;
		675
		676	rcv $SELF, sub {
		677	...
		678	};
		679	}
		680
		681	=cut
		682
		683	sub _spawn {
		684	my $port = shift;
		685	my $init = shift;
		686
		687	local $SELF = "$NODE#$port";
		688	eval {
		689	&{ load_func $init }
		690	};
		691	_self_die if $@;
		692	}
		693
		694	sub spawn(@) {
		695	my ($noderef, undef) = split /#/, shift, 2;
		696
		697	my $id = "$RUNIQ." . $ID++;
		698
		699	$_[0] =~ /::/
		700	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		701
		702	($NODE{$noderef} \|\| add_node $noderef)
		703	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		704
		705	"$noderef#$id"
		706	}
277		707
278	=back	708	=back
279		709
280	=head1 NODE MESSAGES	710	=head1 NODE MESSAGES
281		711
282	Nodes understand the following messages sent to them. Many of them take	712	Nodes understand the following messages sent to them. Many of them take
283	arguments called C<@reply>, which will simply be used to compose a reply	713	arguments called C<@reply>, which will simply be used to compose a reply
284	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	714	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
285	the remaining arguments are simply the message data.	715	the remaining arguments are simply the message data.
286		716
		717	While other messages exist, they are not public and subject to change.
		718
287	=over 4	719	=over 4
288		720
289	=cut	721	=cut
290		722
291	=item wkp => $name, @reply	723	=item lookup => $name, @reply
292		724
293	Replies with the port ID of the specified well-known port, or C<undef>.	725	Replies with the port ID of the specified well-known port, or C<undef>.
294		726
295	=item devnull => ...	727	=item devnull => ...
296		728
…		…
319	snd $NODE, time => $myport, timereply => 1, 2;	751	snd $NODE, time => $myport, timereply => 1, 2;
320	# => snd $myport, timereply => 1, 2, <time>	752	# => snd $myport, timereply => 1, 2, <time>
321		753
322	=back	754	=back
323		755
		756	=head1 AnyEvent::MP vs. Distributed Erlang
		757
		758	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		759	== aemp node, Erlang process == aemp port), so many of the documents and
		760	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		761	sample:
		762
		763	http://www.Erlang.se/doc/programming_rules.shtml
		764	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		765	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		766	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		767
		768	Despite the similarities, there are also some important differences:
		769
		770	=over 4
		771
		772	=item * Node references contain the recipe on how to contact them.
		773
		774	Erlang relies on special naming and DNS to work everywhere in the
		775	same way. AEMP relies on each node knowing it's own address(es), with
		776	convenience functionality.
		777
		778	This means that AEMP requires a less tightly controlled environment at the
		779	cost of longer node references and a slightly higher management overhead.
		780
		781	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		782
		783	Erlang uses processes that selctively receive messages, and therefore
		784	needs a queue. AEMP is event based, queuing messages would serve no useful
		785	purpose.
		786
		787	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		788
		789	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		790
		791	Sending messages in Erlang is synchronous and blocks the process. AEMP
		792	sends are immediate, connection establishment is handled in the
		793	background.
		794
		795	=item * Erlang can silently lose messages, AEMP cannot.
		796
		797	Erlang makes few guarantees on messages delivery - messages can get lost
		798	without any of the processes realising it (i.e. you send messages a, b,
		799	and c, and the other side only receives messages a and c).
		800
		801	AEMP guarantees correct ordering, and the guarantee that there are no
		802	holes in the message sequence.
		803
		804	=item * In Erlang, processes can be declared dead and later be found to be
		805	alive.
		806
		807	In Erlang it can happen that a monitored process is declared dead and
		808	linked processes get killed, but later it turns out that the process is
		809	still alive - and can receive messages.
		810
		811	In AEMP, when port monitoring detects a port as dead, then that port will
		812	eventually be killed - it cannot happen that a node detects a port as dead
		813	and then later sends messages to it, finding it is still alive.
		814
		815	=item * Erlang can send messages to the wrong port, AEMP does not.
		816
		817	In Erlang it is quite possible that a node that restarts reuses a process
		818	ID known to other nodes for a completely different process, causing
		819	messages destined for that process to end up in an unrelated process.
		820
		821	AEMP never reuses port IDs, so old messages or old port IDs floating
		822	around in the network will not be sent to an unrelated port.
		823
		824	=item * Erlang uses unprotected connections, AEMP uses secure
		825	authentication and can use TLS.
		826
		827	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		828	securely authenticate nodes.
		829
		830	=item * The AEMP protocol is optimised for both text-based and binary
		831	communications.
		832
		833	The AEMP protocol, unlike the Erlang protocol, supports both
		834	language-independent text-only protocols (good for debugging) and binary,
		835	language-specific serialisers (e.g. Storable).
		836
		837	It has also been carefully designed to be implementable in other languages
		838	with a minimum of work while gracefully degrading fucntionality to make the
		839	protocol simple.
		840
		841	=item * AEMP has more flexible monitoring options than Erlang.
		842
		843	In Erlang, you can chose to receive I<all> exit signals as messages
		844	or I<none>, there is no in-between, so monitoring single processes is
		845	difficult to implement. Monitoring in AEMP is more flexible than in
		846	Erlang, as one can choose between automatic kill, exit message or callback
		847	on a per-process basis.
		848
		849	=item * Erlang tries to hide remote/local connections, AEMP does not.
		850
		851	Monitoring in Erlang is not an indicator of process death/crashes,
		852	as linking is (except linking is unreliable in Erlang).
		853
		854	In AEMP, you don't "look up" registered port names or send to named ports
		855	that might or might not be persistent. Instead, you normally spawn a port
		856	on the remote node. The init function monitors the you, and you monitor
		857	the remote port. Since both monitors are local to the node, they are much
		858	more reliable.
		859
		860	This also saves round-trips and avoids sending messages to the wrong port
		861	(hard to do in Erlang).
		862
		863	=back
		864
		865	=head1 RATIONALE
		866
		867	=over 4
		868
		869	=item Why strings for ports and noderefs, why not objects?
		870
		871	We considered "objects", but found that the actual number of methods
		872	thatc an be called are very low. Since port IDs and noderefs travel over
		873	the network frequently, the serialising/deserialising would add lots of
		874	overhead, as well as having to keep a proxy object.
		875
		876	Strings can easily be printed, easily serialised etc. and need no special
		877	procedures to be "valid".
		878
		879	And a a miniport consists of a single closure stored in a global hash - it
		880	can't become much cheaper.
		881
		882	=item Why favour JSON, why not real serialising format such as Storable?
		883
		884	In fact, any AnyEvent::MP node will happily accept Storable as framing
		885	format, but currently there is no way to make a node use Storable by
		886	default.
		887
		888	The default framing protocol is JSON because a) JSON::XS is many times
		889	faster for small messages and b) most importantly, after years of
		890	experience we found that object serialisation is causing more problems
		891	than it gains: Just like function calls, objects simply do not travel
		892	easily over the network, mostly because they will always be a copy, so you
		893	always have to re-think your design.
		894
		895	Keeping your messages simple, concentrating on data structures rather than
		896	objects, will keep your messages clean, tidy and efficient.
		897
		898	=back
		899
324	=head1 SEE ALSO	900	=head1 SEE ALSO
325		901
326	L<AnyEvent>.	902	L<AnyEvent>.
327		903
328	=head1 AUTHOR	904	=head1 AUTHOR

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Revision 1.48 by root, Thu Aug 13 02:59:42 2009 UTC