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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.16 by root, Sun Aug 2 19:29:41 2009 UTC vs.
Revision 1.53 by root, Fri Aug 14 15:31:21 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
9	NODE # returns this node identifier
10	$NODE # contains this node identifier	9	$NODE # contains this node's noderef
		10	NODE # returns this node's noderef
		11	NODE $port # returns the noderef of the port
11		12
		13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node; # -OR-
		17	initialise_node "localhost:4040"; # -OR-
		18	initialise_node "slave/", "localhost:4040"
		19
		20	# ports are message endpoints
		21
		22	# sending messages
12	snd $port, type => data...;	23	snd $port, type => data...;
		24	snd $port, @msg;
		25	snd @msg_with_first_element_being_a_port;
13		26
14	rcv $port, smartmatch => $cb->($port, @msg);	27	# creating/using ports, the simple way
		28	my $simple_port = port { my @msg = @_; 0 };
15		29
16	# examples:	30	# creating/using ports, tagged message matching
		31	my $port = port;
17	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
18	rcv $port1, pong => sub { warn "pong received\n" };	33	rcv $port, pong => sub { warn "pong received\n"; 0 };
19	snd $port2, ping => $port1;
20		34
21	# more, smarter, matches (_any_ is exported by this module)	35	# create a port on another node
22	rcv $port, [child_died => $pid] => sub { ...	36	my $port = spawn $node, $initfunc, @initdata;
23	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	37
		38	# monitoring
		39	mon $port, $cb->(@msg) # callback is invoked on death
		40	mon $port, $otherport # kill otherport on abnormal death
		41	mon $port, $otherport, @msg # send message on death
		42
		43	=head1 CURRENT STATUS
		44
		45	AnyEvent::MP - stable API, should work
		46	AnyEvent::MP::Intro - outdated
		47	AnyEvent::MP::Kernel - WIP
		48	AnyEvent::MP::Transport - mostly stable
		49
		50	stay tuned.
24		51
25	=head1 DESCRIPTION	52	=head1 DESCRIPTION
26		53
27	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
28		55
29	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
30	on the same or other hosts.	57	on the same or other hosts.
31		58
		59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		60	manual page.
		61
32	At the moment, this module family is severly brokena nd underdocumented,	62	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 -	63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
34	stay tuned!	64	stay tuned!
35		65
36	=head1 CONCEPTS	66	=head1 CONCEPTS
37		67
38	=over 4	68	=over 4
39		69
40	=item port	70	=item port
41		71
42	A port is something you can send messages to with the C<snd> function, and	72	A port is something you can send messages to (with the C<snd> function).
43	you can register C<rcv> handlers with. All C<rcv> handlers will receive	73
		74	Ports allow you to register C<rcv> handlers that can match all or just
44	messages they match, messages will not be queued.	75	some messages. Messages will not be queued.
45		76
46	=item port id - C<noderef#portname>	77	=item port id - C<noderef#portname>
47		78
48	A port id is always the noderef, a hash-mark (C<#>) as separator, followed	79	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
49	by a port name (a printable string of unspecified format).	80	separator, and a port name (a printable string of unspecified format). An
		81	exception is the the node port, whose ID is identical to its node
		82	reference.
50		83
51	=item node	84	=item node
52		85
53	A node is a single process containing at least one port - the node	86	A node is a single process containing at least one port - the node port,
54	port. You can send messages to node ports to let them create new ports,	87	which provides nodes to manage each other remotely, and to create new
55	among other things.	88	ports.
56		89
57	Initially, nodes are either private (single-process only) or hidden	90	Nodes are either private (single-process only), slaves (connected to a
58	(connected to a master node only). Only when they epxlicitly "become	91	master node only) or public nodes (connectable from unrelated nodes).
59	public" can you send them messages from unrelated other nodes.
60		92
61	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
62		94
63	A noderef is a string that either uniquely identifies a given node (for	95	A node reference is a string that either simply identifies the node (for
64	private and hidden nodes), or contains a recipe on how to reach a given	96	private and slave nodes), or contains a recipe on how to reach a given
65	node (for public nodes).	97	node (for public nodes).
66		98
		99	This recipe is simply a comma-separated list of C<address:port> pairs (for
		100	TCP/IP, other protocols might look different).
		101
		102	Node references come in two flavours: resolved (containing only numerical
		103	addresses) or unresolved (where hostnames are used instead of addresses).
		104
		105	Before using an unresolved node reference in a message you first have to
		106	resolve it.
		107
67	=back	108	=back
68		109
69	=head1 VARIABLES/FUNCTIONS	110	=head1 VARIABLES/FUNCTIONS
70		111
71	=over 4	112	=over 4
72		113
73	=cut	114	=cut
74		115
75	package AnyEvent::MP;	116	package AnyEvent::MP;
76		117
77	use AnyEvent::MP::Base;	118	use AnyEvent::MP::Kernel;
78		119
79	use common::sense;	120	use common::sense;
80		121
81	use Carp ();	122	use Carp ();
82		123
83	use AE ();	124	use AE ();
84		125
85	use base "Exporter";	126	use base "Exporter";
86		127
87	our $VERSION = '0.02';	128	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		129
88	our @EXPORT = qw(	130	our @EXPORT = qw(
89	NODE $NODE $PORT snd rcv _any_	131	NODE $NODE *SELF node_of _any_
90	create_port create_port_on	132	resolve_node initialise_node
91	create_miniport	133	snd rcv mon kil reg psub spawn
92	become_slave become_public	134	port
93	);	135	);
94		136
		137	our $SELF;
		138
		139	sub _self_die() {
		140	my $msg = $@;
		141	$msg =~ s/\n+$// unless ref $msg;
		142	kil $SELF, die => $msg;
		143	}
		144
95	=item NODE / $NODE	145	=item $thisnode = NODE / $NODE
96		146
97	The C<NODE ()> function and the C<$NODE> variable contain the noderef of	147	The C<NODE> function returns, and the C<$NODE> variable contains the
98	the local node. The value is initialised by a call to C<become_public> or	148	noderef of the local node. The value is initialised by a call to
99	C<become_slave>, after which all local port identifiers become invalid.	149	C<initialise_node>.
100		150
		151	=item $noderef = node_of $port
		152
		153	Extracts and returns the noderef from a port ID or a noderef.
		154
		155	=item initialise_node $noderef, $seednode, $seednode...
		156
		157	=item initialise_node "slave/", $master, $master...
		158
		159	Before a node can talk to other nodes on the network it has to initialise
		160	itself - the minimum a node needs to know is it's own name, and optionally
		161	it should know the noderefs of some other nodes in the network.
		162
		163	This function initialises a node - it must be called exactly once (or
		164	never) before calling other AnyEvent::MP functions.
		165
		166	All arguments (optionally except for the first) are noderefs, which can be
		167	either resolved or unresolved.
		168
		169	The first argument will be looked up in the configuration database first
		170	(if it is C<undef> then the current nodename will be used instead) to find
		171	the relevant configuration profile (see L<aemp>). If none is found then
		172	the default configuration is used. The configuration supplies additional
		173	seed/master nodes and can override the actual noderef.
		174
		175	There are two types of networked nodes, public nodes and slave nodes:
		176
		177	=over 4
		178
		179	=item public nodes
		180
		181	For public nodes, C<$noderef> (supplied either directly to
		182	C<initialise_node> or indirectly via a profile or the nodename) must be a
		183	noderef (possibly unresolved, in which case it will be resolved).
		184
		185	After resolving, the node will bind itself on all endpoints and try to
		186	connect to all additional C<$seednodes> that are specified. Seednodes are
		187	optional and can be used to quickly bootstrap the node into an existing
		188	network.
		189
		190	=item slave nodes
		191
		192	When the C<$noderef> (either as given or overriden by the config file)
		193	is the special string C<slave/>, then the node will become a slave
		194	node. Slave nodes cannot be contacted from outside and will route most of
		195	their traffic to the master node that they attach to.
		196
		197	At least one additional noderef is required (either by specifying it
		198	directly or because it is part of the configuration profile): The node
		199	will try to connect to all of them and will become a slave attached to the
		200	first node it can successfully connect to.
		201
		202	=back
		203
		204	This function will block until all nodes have been resolved and, for slave
		205	nodes, until it has successfully established a connection to a master
		206	server.
		207
		208	Example: become a public node listening on the guessed noderef, or the one
		209	specified via C<aemp> for the current node. This should be the most common
		210	form of invocation for "daemon"-type nodes.
		211
		212	initialise_node;
		213
		214	Example: become a slave node to any of the the seednodes specified via
		215	C<aemp>. This form is often used for commandline clients.
		216
		217	initialise_node "slave/";
		218
		219	Example: become a slave node to any of the specified master servers. This
		220	form is also often used for commandline clients.
		221
		222	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		223
		224	Example: become a public node, and try to contact some well-known master
		225	servers to become part of the network.
		226
		227	initialise_node undef, "master1", "master2";
		228
		229	Example: become a public node listening on port C<4041>.
		230
		231	initialise_node 4041;
		232
		233	Example: become a public node, only visible on localhost port 4044.
		234
		235	initialise_node "localhost:4044";
		236
		237	=item $cv = resolve_node $noderef
		238
		239	Takes an unresolved node reference that may contain hostnames and
		240	abbreviated IDs, resolves all of them and returns a resolved node
		241	reference.
		242
		243	In addition to C<address:port> pairs allowed in resolved noderefs, the
		244	following forms are supported:
		245
		246	=over 4
		247
		248	=item the empty string
		249
		250	An empty-string component gets resolved as if the default port (4040) was
		251	specified.
		252
		253	=item naked port numbers (e.g. C<1234>)
		254
		255	These are resolved by prepending the local nodename and a colon, to be
		256	further resolved.
		257
		258	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		259
		260	These are resolved by using AnyEvent::DNS to resolve them, optionally
		261	looking up SRV records for the C<aemp=4040> port, if no port was
		262	specified.
		263
		264	=back
		265
		266	=item $SELF
		267
		268	Contains the current port id while executing C<rcv> callbacks or C<psub>
		269	blocks.
		270
		271	=item SELF, %SELF, @SELF...
		272
		273	Due to some quirks in how perl exports variables, it is impossible to
		274	just export C<$SELF>, all the symbols called C<SELF> are exported by this
		275	module, but only C<$SELF> is currently used.
		276
101	=item snd $portid, type => @data	277	=item snd $port, type => @data
102		278
103	=item snd $portid, @msg	279	=item snd $port, @msg
104		280
105	Send the given message to the given port ID, which can identify either	281	Send the given message to the given port ID, which can identify either
106	a local or a remote port, and can be either a string or soemthignt hat	282	a local or a remote port, and must be a port ID.
107	stringifies a sa port ID (such as a port object :).
108		283
109	While the message can be about anything, it is highly recommended to use a	284	While the message can be about anything, it is highly recommended to use a
110	string as first element (a portid, or some word that indicates a request	285	string as first element (a port ID, or some word that indicates a request
111	type etc.).	286	type etc.).
112		287
113	The message data effectively becomes read-only after a call to this	288	The message data effectively becomes read-only after a call to this
114	function: modifying any argument is not allowed and can cause many	289	function: modifying any argument is not allowed and can cause many
115	problems.	290	problems.
…		…
118	JSON is used, then only strings, numbers and arrays and hashes consisting	293	JSON is used, then only strings, numbers and arrays and hashes consisting
119	of those are allowed (no objects). When Storable is used, then anything	294	of those are allowed (no objects). When Storable is used, then anything
120	that Storable can serialise and deserialise is allowed, and for the local	295	that Storable can serialise and deserialise is allowed, and for the local
121	node, anything can be passed.	296	node, anything can be passed.
122		297
123	=item $local_port = create_port	298	=item $local_port = port
124		299
125	Create a new local port object. See the next section for allowed methods.	300	Create a new local port object and returns its port ID. Initially it has
		301	no callbacks set and will throw an error when it receives messages.
126		302
127	=cut	303	=item $local_port = port { my @msg = @_ }
128		304
129	sub create_port {	305	Creates a new local port, and returns its ID. Semantically the same as
130	my $id = "$AnyEvent::MP::Base::UNIQ." . $AnyEvent::MP::Base::ID++;	306	creating a port and calling C<rcv $port, $callback> on it.
131		307
132	my $self = bless {	308	The block will be called for every message received on the port, with the
133	id => "$NODE#$id",	309	global variable C<$SELF> set to the port ID. Runtime errors will cause the
134	names => [$id],	310	port to be C<kil>ed. The message will be passed as-is, no extra argument
135	}, "AnyEvent::MP::Port";	311	(i.e. no port ID) will be passed to the callback.
136		312
137	$AnyEvent::MP::Base::PORT{$id} = sub {	313	If you want to stop/destroy the port, simply C<kil> it:
138	unshift @_, $self;
139		314
140	for (@{ $self->{rc0}{$_[1]} }) {	315	my $port = port {
141	$_ && &{$_->[0]}	316	my @msg = @_;
142	&& undef $_;	317	...
		318	kil $SELF;
		319	};
		320
		321	=cut
		322
		323	sub rcv($@);
		324
		325	sub _kilme {
		326	die "received message on port without callback";
		327	}
		328
		329	sub port(;&) {
		330	my $id = "$UNIQ." . $ID++;
		331	my $port = "$NODE#$id";
		332
		333	rcv $port, shift \|\| \&_kilme;
		334
		335	$port
		336	}
		337
		338	=item rcv $local_port, $callback->(@msg)
		339
		340	Replaces the default callback on the specified port. There is no way to
		341	remove the default callback: use C<sub { }> to disable it, or better
		342	C<kil> the port when it is no longer needed.
		343
		344	The global C<$SELF> (exported by this module) contains C<$port> while
		345	executing the callback. Runtime errors during callback execution will
		346	result in the port being C<kil>ed.
		347
		348	The default callback received all messages not matched by a more specific
		349	C<tag> match.
		350
		351	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		352
		353	Register callbacks to be called on messages starting with the given tag on
		354	the given port (and return the port), or unregister it (when C<$callback>
		355	is C<$undef>).
		356
		357	The original message will be passed to the callback, after the first
		358	element (the tag) has been removed. The callback will use the same
		359	environment as the default callback (see above).
		360
		361	Example: create a port and bind receivers on it in one go.
		362
		363	my $port = rcv port,
		364	msg1 => sub { ... },
		365	msg2 => sub { ... },
		366	;
		367
		368	Example: create a port, bind receivers and send it in a message elsewhere
		369	in one go:
		370
		371	snd $otherport, reply =>
		372	rcv port,
		373	msg1 => sub { ... },
		374	...
		375	;
		376
		377	=cut
		378
		379	sub rcv($@) {
		380	my $port = shift;
		381	my ($noderef, $portid) = split /#/, $port, 2;
		382
		383	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		384	or Carp::croak "$port: rcv can only be called on local ports, caught";
		385
		386	while (@_) {
		387	if (ref $_[0]) {
		388	if (my $self = $PORT_DATA{$portid}) {
		389	"AnyEvent::MP::Port" eq ref $self
		390	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		391
		392	$self->[2] = shift;
		393	} else {
		394	my $cb = shift;
		395	$PORT{$portid} = sub {
		396	local $SELF = $port;
		397	eval { &$cb }; _self_die if $@;
		398	};
		399	}
		400	} elsif (defined $_[0]) {
		401	my $self = $PORT_DATA{$portid} \|\|= do {
		402	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		403
		404	$PORT{$portid} = sub {
		405	local $SELF = $port;
		406
		407	if (my $cb = $self->[1]{$_[0]}) {
		408	shift;
		409	eval { &$cb }; _self_die if $@;
		410	} else {
		411	&{ $self->[0] };
		412	}
		413	};
		414
		415	$self
		416	};
		417
		418	"AnyEvent::MP::Port" eq ref $self
		419	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		420
		421	my ($tag, $cb) = splice @_, 0, 2;
		422
		423	if (defined $cb) {
		424	$self->[1]{$tag} = $cb;
		425	} else {
		426	delete $self->[1]{$tag};
		427	}
143	}	428	}
		429	}
144		430
145	for (@{ $self->{rcv}{$_[1]} }) {	431	$port
146	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	432	}
147	&& &{$_->[0]}	433
148	&& undef $_;	434	=item $closure = psub { BLOCK }
		435
		436	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		437	closure is executed, sets up the environment in the same way as in C<rcv>
		438	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		439
		440	This is useful when you register callbacks from C<rcv> callbacks:
		441
		442	rcv delayed_reply => sub {
		443	my ($delay, @reply) = @_;
		444	my $timer = AE::timer $delay, 0, psub {
		445	snd @reply, $SELF;
		446	};
		447	};
		448
		449	=cut
		450
		451	sub psub(&) {
		452	my $cb = shift;
		453
		454	my $port = $SELF
		455	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		456
		457	sub {
		458	local $SELF = $port;
		459
		460	if (wantarray) {
		461	my @res = eval { &$cb };
		462	_self_die if $@;
		463	@res
		464	} else {
		465	my $res = eval { &$cb };
		466	_self_die if $@;
		467	$res
149	}	468	}
150
151	for (@{ $self->{any} }) {
152	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
153	&& &{$_->[0]}
154	&& undef $_;
155	}
156	};
157
158	$self
159	}
160
161	=item $portid = miniport { my @msg = @_; $finished }
162
163	Creates a "mini port", that is, a very lightweight port without any
164	pattern matching behind it, and returns its ID.
165
166	The block will be called for every message received on the port. When the
167	callback returns a true value its job is considered "done" and the port
168	will be destroyed. Otherwise it will stay alive.
169
170	The message will be passed as-is, no extra argument (ie.. no port id) will
171	be passed to the callback.
172
173	If you need the local port id in the callback, this works nicely:
174
175	my $port; $port = miniport {
176	snd $otherport, reply => $port;
177	};
178
179	=cut
180
181	sub miniport(&) {
182	my $cb = shift;
183	my $id = "$AnyEvent::MP::Base::UNIQ." . $AnyEvent::MP::Base::ID++;
184
185	$AnyEvent::MP::Base::PORT{$id} = sub {
186	&$cb
187	and delete $AnyEvent::MP::Base::PORT{$id};
188	};
189
190	"$NODE#$id"
191	}
192
193	package AnyEvent::MP::Port;
194
195	=back
196
197	=head1 METHODS FOR PORT OBJECTS
198
199	=over 4
200
201	=item "$port"
202
203	A port object stringifies to its port ID, so can be used directly for
204	C<snd> operations.
205
206	=cut
207
208	use overload
209	'""' => sub { $_[0]{id} },
210	fallback => 1;
211
212	=item $port->rcv (type => $callback->($port, @msg))
213
214	=item $port->rcv ($smartmatch => $callback->($port, @msg))
215
216	=item $port->rcv ([$smartmatch...] => $callback->($port, @msg))
217
218	Register a callback on the given port.
219
220	The callback has to return a true value when its work is done, after
221	which is will be removed, or a false value in which case it will stay
222	registered.
223
224	If the match is an array reference, then it will be matched against the
225	first elements of the message, otherwise only the first element is being
226	matched.
227
228	Any element in the match that is specified as C<_any_> (a function
229	exported by this module) matches any single element of the message.
230
231	While not required, it is highly recommended that the first matching
232	element is a string identifying the message. The one-string-only match is
233	also the most efficient match (by far).
234
235	=cut
236
237	sub rcv($@) {
238	my ($self, $match, $cb) = @_;
239
240	if (!ref $match) {
241	push @{ $self->{rc0}{$match} }, [$cb];
242	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
243	my ($type, @match) = @$match;
244	@match
245	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
246	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
247	} else {
248	push @{ $self->{any} }, [$cb, $match];
249	}	469	}
250	}	470	}
251		471
252	=item $port->register ($name)	472	=item $guard = mon $port, $cb->(@reason)
253		473
254	Registers the given port under the well known name C<$name>. If the name	474	=item $guard = mon $port, $rcvport
255	already exists it is replaced.
256		475
257	A port can only be registered under one well known name.	476	=item $guard = mon $port
258		477
259	=cut	478	=item $guard = mon $port, $rcvport, @msg
260		479
261	sub register {	480	Monitor the given port and do something when the port is killed or
262	my ($self, $name) = @_;	481	messages to it were lost, and optionally return a guard that can be used
		482	to stop monitoring again.
263		483
264	$self->{wkname} = $name;	484	C<mon> effectively guarantees that, in the absence of hardware failures,
265	$AnyEvent::MP::Base::WKP{$name} = "$self";	485	that after starting the monitor, either all messages sent to the port
		486	will arrive, or the monitoring action will be invoked after possible
		487	message loss has been detected. No messages will be lost "in between"
		488	(after the first lost message no further messages will be received by the
		489	port). After the monitoring action was invoked, further messages might get
		490	delivered again.
		491
		492	In the first form (callback), the callback is simply called with any
		493	number of C<@reason> elements (no @reason means that the port was deleted
		494	"normally"). Note also that I<< the callback B<must> never die >>, so use
		495	C<eval> if unsure.
		496
		497	In the second form (another port given), the other port (C<$rcvport>)
		498	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		499	"normal" kils nothing happens, while under all other conditions, the other
		500	port is killed with the same reason.
		501
		502	The third form (kill self) is the same as the second form, except that
		503	C<$rvport> defaults to C<$SELF>.
		504
		505	In the last form (message), a message of the form C<@msg, @reason> will be
		506	C<snd>.
		507
		508	As a rule of thumb, monitoring requests should always monitor a port from
		509	a local port (or callback). The reason is that kill messages might get
		510	lost, just like any other message. Another less obvious reason is that
		511	even monitoring requests can get lost (for exmaple, when the connection
		512	to the other node goes down permanently). When monitoring a port locally
		513	these problems do not exist.
		514
		515	Example: call a given callback when C<$port> is killed.
		516
		517	mon $port, sub { warn "port died because of <@_>\n" };
		518
		519	Example: kill ourselves when C<$port> is killed abnormally.
		520
		521	mon $port;
		522
		523	Example: send us a restart message when another C<$port> is killed.
		524
		525	mon $port, $self => "restart";
		526
		527	=cut
		528
		529	sub mon {
		530	my ($noderef, $port) = split /#/, shift, 2;
		531
		532	my $node = $NODE{$noderef} \|\| add_node $noderef;
		533
		534	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		535
		536	unless (ref $cb) {
		537	if (@_) {
		538	# send a kill info message
		539	my (@msg) = ($cb, @_);
		540	$cb = sub { snd @msg, @_ };
		541	} else {
		542	# simply kill other port
		543	my $port = $cb;
		544	$cb = sub { kil $port, @_ if @_ };
		545	}
		546	}
		547
		548	$node->monitor ($port, $cb);
		549
		550	defined wantarray
		551	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
266	}	552	}
267		553
268	=item $port->destroy	554	=item $guard = mon_guard $port, $ref, $ref...
269		555
270	Explicitly destroy/remove/nuke/vaporise the port.	556	Monitors the given C<$port> and keeps the passed references. When the port
		557	is killed, the references will be freed.
271		558
272	Ports are normally kept alive by there mere existance alone, and need to	559	Optionally returns a guard that will stop the monitoring.
273	be destroyed explicitly.
274		560
275	=cut	561	This function is useful when you create e.g. timers or other watchers and
		562	want to free them when the port gets killed:
276		563
277	sub destroy {	564	$port->rcv (start => sub {
278	my ($self) = @_;	565	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		566	undef $timer if 0.9 < rand;
		567	});
		568	});
279		569
280	delete $AnyEvent::MP::Base::WKP{ $self->{wkname} };	570	=cut
281		571
282	delete $AnyEvent::MP::Base::PORT{$_}	572	sub mon_guard {
283	for @{ $self->{names} };	573	my ($port, @refs) = @_;
		574
		575	#TODO: mon-less form?
		576
		577	mon $port, sub { 0 && @refs }
284	}	578	}
285		579
286	=back	580	=item kil $port[, @reason]
287		581
288	=head1 FUNCTIONS FOR NODES	582	Kill the specified port with the given C<@reason>.
289		583
290	=over 4	584	If no C<@reason> is specified, then the port is killed "normally" (linked
		585	ports will not be kileld, or even notified).
291		586
292	=item mon $noderef, $callback->($noderef, $status, $)	587	Otherwise, linked ports get killed with the same reason (second form of
		588	C<mon>, see below).
293		589
294	Monitors the given noderef.	590	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		591	will be reported as reason C<< die => $@ >>.
295		592
296	=item become_public endpoint...	593	Transport/communication errors are reported as C<< transport_error =>
		594	$message >>.
297		595
298	Tells the node to become a public node, i.e. reachable from other nodes.
299
300	If no arguments are given, or the first argument is C<undef>, then
301	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the
302	local nodename resolves to.
303
304	Otherwise the first argument must be an array-reference with transport
305	endpoints ("ip:port", "hostname:port") or port numbers (in which case the
306	local nodename is used as hostname). The endpoints are all resolved and
307	will become the node reference.
308
309	=cut	596	=cut
		597
		598	=item $port = spawn $node, $initfunc[, @initdata]
		599
		600	Creates a port on the node C<$node> (which can also be a port ID, in which
		601	case it's the node where that port resides).
		602
		603	The port ID of the newly created port is return immediately, and it is
		604	permissible to immediately start sending messages or monitor the port.
		605
		606	After the port has been created, the init function is
		607	called. This function must be a fully-qualified function name
		608	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		609	program, use C<::name>.
		610
		611	If the function doesn't exist, then the node tries to C<require>
		612	the package, then the package above the package and so on (e.g.
		613	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		614	exists or it runs out of package names.
		615
		616	The init function is then called with the newly-created port as context
		617	object (C<$SELF>) and the C<@initdata> values as arguments.
		618
		619	A common idiom is to pass your own port, monitor the spawned port, and
		620	in the init function, monitor the original port. This two-way monitoring
		621	ensures that both ports get cleaned up when there is a problem.
		622
		623	Example: spawn a chat server port on C<$othernode>.
		624
		625	# this node, executed from within a port context:
		626	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		627	mon $server;
		628
		629	# init function on C<$othernode>
		630	sub connect {
		631	my ($srcport) = @_;
		632
		633	mon $srcport;
		634
		635	rcv $SELF, sub {
		636	...
		637	};
		638	}
		639
		640	=cut
		641
		642	sub _spawn {
		643	my $port = shift;
		644	my $init = shift;
		645
		646	local $SELF = "$NODE#$port";
		647	eval {
		648	&{ load_func $init }
		649	};
		650	_self_die if $@;
		651	}
		652
		653	sub spawn(@) {
		654	my ($noderef, undef) = split /#/, shift, 2;
		655
		656	my $id = "$RUNIQ." . $ID++;
		657
		658	$_[0] =~ /::/
		659	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		660
		661	($NODE{$noderef} \|\| add_node $noderef)
		662	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		663
		664	"$noderef#$id"
		665	}
310		666
311	=back	667	=back
312		668
313	=head1 NODE MESSAGES	669	=head1 NODE MESSAGES
314		670
315	Nodes understand the following messages sent to them. Many of them take	671	Nodes understand the following messages sent to them. Many of them take
316	arguments called C<@reply>, which will simply be used to compose a reply	672	arguments called C<@reply>, which will simply be used to compose a reply
317	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	673	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
318	the remaining arguments are simply the message data.	674	the remaining arguments are simply the message data.
319		675
		676	While other messages exist, they are not public and subject to change.
		677
320	=over 4	678	=over 4
321		679
322	=cut	680	=cut
323		681
324	=item wkp => $name, @reply	682	=item lookup => $name, @reply
325		683
326	Replies with the port ID of the specified well-known port, or C<undef>.	684	Replies with the port ID of the specified well-known port, or C<undef>.
327		685
328	=item devnull => ...	686	=item devnull => ...
329		687
…		…
352	snd $NODE, time => $myport, timereply => 1, 2;	710	snd $NODE, time => $myport, timereply => 1, 2;
353	# => snd $myport, timereply => 1, 2, <time>	711	# => snd $myport, timereply => 1, 2, <time>
354		712
355	=back	713	=back
356		714
		715	=head1 AnyEvent::MP vs. Distributed Erlang
		716
		717	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		718	== aemp node, Erlang process == aemp port), so many of the documents and
		719	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		720	sample:
		721
		722	http://www.Erlang.se/doc/programming_rules.shtml
		723	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		724	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		725	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		726
		727	Despite the similarities, there are also some important differences:
		728
		729	=over 4
		730
		731	=item * Node references contain the recipe on how to contact them.
		732
		733	Erlang relies on special naming and DNS to work everywhere in the
		734	same way. AEMP relies on each node knowing it's own address(es), with
		735	convenience functionality.
		736
		737	This means that AEMP requires a less tightly controlled environment at the
		738	cost of longer node references and a slightly higher management overhead.
		739
		740	=item Erlang has a "remote ports are like local ports" philosophy, AEMP
		741	uses "local ports are like remote ports".
		742
		743	The failure modes for local ports are quite different (runtime errors
		744	only) then for remote ports - when a local port dies, you I<know> it dies,
		745	when a connection to another node dies, you know nothing about the other
		746	port.
		747
		748	Erlang pretends remote ports are as reliable as local ports, even when
		749	they are not.
		750
		751	AEMP encourages a "treat remote ports differently" philosophy, with local
		752	ports being the special case/exception, where transport errors cannot
		753	occur.
		754
		755	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		756
		757	Erlang uses processes that selectively receive messages, and therefore
		758	needs a queue. AEMP is event based, queuing messages would serve no
		759	useful purpose. For the same reason the pattern-matching abilities of
		760	AnyEvent::MP are more limited, as there is little need to be able to
		761	filter messages without dequeing them.
		762
		763	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		764
		765	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		766
		767	Sending messages in Erlang is synchronous and blocks the process (and
		768	so does not need a queue that can overflow). AEMP sends are immediate,
		769	connection establishment is handled in the background.
		770
		771	=item * Erlang suffers from silent message loss, AEMP does not.
		772
		773	Erlang makes few guarantees on messages delivery - messages can get lost
		774	without any of the processes realising it (i.e. you send messages a, b,
		775	and c, and the other side only receives messages a and c).
		776
		777	AEMP guarantees correct ordering, and the guarantee that there are no
		778	holes in the message sequence.
		779
		780	=item * In Erlang, processes can be declared dead and later be found to be
		781	alive.
		782
		783	In Erlang it can happen that a monitored process is declared dead and
		784	linked processes get killed, but later it turns out that the process is
		785	still alive - and can receive messages.
		786
		787	In AEMP, when port monitoring detects a port as dead, then that port will
		788	eventually be killed - it cannot happen that a node detects a port as dead
		789	and then later sends messages to it, finding it is still alive.
		790
		791	=item * Erlang can send messages to the wrong port, AEMP does not.
		792
		793	In Erlang it is quite likely that a node that restarts reuses a process ID
		794	known to other nodes for a completely different process, causing messages
		795	destined for that process to end up in an unrelated process.
		796
		797	AEMP never reuses port IDs, so old messages or old port IDs floating
		798	around in the network will not be sent to an unrelated port.
		799
		800	=item * Erlang uses unprotected connections, AEMP uses secure
		801	authentication and can use TLS.
		802
		803	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		804	securely authenticate nodes.
		805
		806	=item * The AEMP protocol is optimised for both text-based and binary
		807	communications.
		808
		809	The AEMP protocol, unlike the Erlang protocol, supports both
		810	language-independent text-only protocols (good for debugging) and binary,
		811	language-specific serialisers (e.g. Storable).
		812
		813	It has also been carefully designed to be implementable in other languages
		814	with a minimum of work while gracefully degrading fucntionality to make the
		815	protocol simple.
		816
		817	=item * AEMP has more flexible monitoring options than Erlang.
		818
		819	In Erlang, you can chose to receive I<all> exit signals as messages
		820	or I<none>, there is no in-between, so monitoring single processes is
		821	difficult to implement. Monitoring in AEMP is more flexible than in
		822	Erlang, as one can choose between automatic kill, exit message or callback
		823	on a per-process basis.
		824
		825	=item * Erlang tries to hide remote/local connections, AEMP does not.
		826
		827	Monitoring in Erlang is not an indicator of process death/crashes,
		828	as linking is (except linking is unreliable in Erlang).
		829
		830	In AEMP, you don't "look up" registered port names or send to named ports
		831	that might or might not be persistent. Instead, you normally spawn a port
		832	on the remote node. The init function monitors the you, and you monitor
		833	the remote port. Since both monitors are local to the node, they are much
		834	more reliable.
		835
		836	This also saves round-trips and avoids sending messages to the wrong port
		837	(hard to do in Erlang).
		838
		839	=back
		840
		841	=head1 RATIONALE
		842
		843	=over 4
		844
		845	=item Why strings for ports and noderefs, why not objects?
		846
		847	We considered "objects", but found that the actual number of methods
		848	thatc an be called are very low. Since port IDs and noderefs travel over
		849	the network frequently, the serialising/deserialising would add lots of
		850	overhead, as well as having to keep a proxy object.
		851
		852	Strings can easily be printed, easily serialised etc. and need no special
		853	procedures to be "valid".
		854
		855	And a a miniport consists of a single closure stored in a global hash - it
		856	can't become much cheaper.
		857
		858	=item Why favour JSON, why not real serialising format such as Storable?
		859
		860	In fact, any AnyEvent::MP node will happily accept Storable as framing
		861	format, but currently there is no way to make a node use Storable by
		862	default.
		863
		864	The default framing protocol is JSON because a) JSON::XS is many times
		865	faster for small messages and b) most importantly, after years of
		866	experience we found that object serialisation is causing more problems
		867	than it gains: Just like function calls, objects simply do not travel
		868	easily over the network, mostly because they will always be a copy, so you
		869	always have to re-think your design.
		870
		871	Keeping your messages simple, concentrating on data structures rather than
		872	objects, will keep your messages clean, tidy and efficient.
		873
		874	=back
		875
357	=head1 SEE ALSO	876	=head1 SEE ALSO
358		877
359	L<AnyEvent>.	878	L<AnyEvent>.
360		879
361	=head1 AUTHOR	880	=head1 AUTHOR

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Revision 1.53 by root, Fri Aug 14 15:31:21 2009 UTC