[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 1.49 by root, Thu Aug 13 15:29:58 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		51	AnyEvent::MP::Intro - outdated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, $master...
		165
		166	Before a node can talk to other nodes on the network it has to initialise
		167	itself - the minimum a node needs to know is it's own name, and optionally
		168	it should know the noderefs of some other nodes in the network.
		169
		170	This function initialises a node - it must be called exactly once (or
		171	never) before calling other AnyEvent::MP functions.
		172
		173	All arguments (optionally except for the first) are noderefs, which can be
		174	either resolved or unresolved.
		175
		176	The first argument will be looked up in the configuration database first
		177	(if it is C<undef> then the current nodename will be used instead) to find
		178	the relevant configuration profile (see L<aemp>). If none is found then
		179	the default configuration is used. The configuration supplies additional
		180	seed/master nodes and can override the actual noderef.
		181
		182	There are two types of networked nodes, public nodes and slave nodes:
		183
		184	=over 4
		185
		186	=item public nodes
		187
		188	For public nodes, C<$noderef> (supplied either directly to
		189	C<initialise_node> or indirectly via a profile or the nodename) must be a
		190	noderef (possibly unresolved, in which case it will be resolved).
		191
		192	After resolving, the node will bind itself on all endpoints and try to
		193	connect to all additional C<$seednodes> that are specified. Seednodes are
		194	optional and can be used to quickly bootstrap the node into an existing
		195	network.
		196
		197	=item slave nodes
		198
		199	When the C<$noderef> (either as given or overriden by the config file)
		200	is the special string C<slave/>, then the node will become a slave
		201	node. Slave nodes cannot be contacted from outside and will route most of
		202	their traffic to the master node that they attach to.
		203
		204	At least one additional noderef is required (either by specifying it
		205	directly or because it is part of the configuration profile): The node
		206	will try to connect to all of them and will become a slave attached to the
		207	first node it can successfully connect to.
		208
		209	=back
		210
		211	This function will block until all nodes have been resolved and, for slave
		212	nodes, until it has successfully established a connection to a master
		213	server.
		214
		215	Example: become a public node listening on the guessed noderef, or the one
		216	specified via C<aemp> for the current node. This should be the most common
		217	form of invocation for "daemon"-type nodes.
		218
		219	initialise_node;
		220
		221	Example: become a slave node to any of the the seednodes specified via
		222	C<aemp>. This form is often used for commandline clients.
		223
		224	initialise_node "slave/";
		225
		226	Example: become a slave node to any of the specified master servers. This
		227	form is also often used for commandline clients.
		228
		229	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
		230
		231	Example: become a public node, and try to contact some well-known master
		232	servers to become part of the network.
		233
		234	initialise_node undef, "master1", "master2";
		235
		236	Example: become a public node listening on port C<4041>.
		237
		238	initialise_node 4041;
		239
		240	Example: become a public node, only visible on localhost port 4044.
		241
		242	initialise_node "localhost:4044";
		243
		244	=item $cv = resolve_node $noderef
		245
		246	Takes an unresolved node reference that may contain hostnames and
		247	abbreviated IDs, resolves all of them and returns a resolved node
		248	reference.
		249
		250	In addition to C<address:port> pairs allowed in resolved noderefs, the
		251	following forms are supported:
		252
		253	=over 4
		254
		255	=item the empty string
		256
		257	An empty-string component gets resolved as if the default port (4040) was
		258	specified.
		259
		260	=item naked port numbers (e.g. C<1234>)
		261
		262	These are resolved by prepending the local nodename and a colon, to be
		263	further resolved.
		264
		265	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		266
		267	These are resolved by using AnyEvent::DNS to resolve them, optionally
		268	looking up SRV records for the C<aemp=4040> port, if no port was
		269	specified.
		270
		271	=back
		272
		273	=item $SELF
		274
		275	Contains the current port id while executing C<rcv> callbacks or C<psub>
		276	blocks.
		277
		278	=item SELF, %SELF, @SELF...
		279
		280	Due to some quirks in how perl exports variables, it is impossible to
		281	just export C<$SELF>, all the symbols called C<SELF> are exported by this
		282	module, but only C<$SELF> is currently used.
		283
100	=item snd $portid, type => @data	284	=item snd $port, type => @data
101		285
102	=item snd $portid, @msg	286	=item snd $port, @msg
103		287
104	Send the given message to the given port ID, which can identify either	288	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	289	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 :).	290	stringifies a sa port ID (such as a port object :).
107		291
…		…
117	JSON is used, then only strings, numbers and arrays and hashes consisting	301	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	302	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	303	that Storable can serialise and deserialise is allowed, and for the local
120	node, anything can be passed.	304	node, anything can be passed.
121		305
122	=item $local_port = create_port	306	=item $local_port = port
123		307
124	Create a new local port object. See the next section for allowed methods.	308	Create a new local port object that can be used either as a pattern
		309	matching port ("full port") or a single-callback port ("miniport"),
		310	depending on how C<rcv> callbacks are bound to the object.
125		311
126	=cut	312	=item $port = port { my @msg = @_; $finished }
127		313
128	sub create_port {	314	Creates a "miniport", that is, a very lightweight port without any pattern
129	my $id = "$AnyEvent::MP::Base::UNIQ." . ++$AnyEvent::MP::Base::ID;	315	matching behind it, and returns its ID. Semantically the same as creating
		316	a port and calling C<rcv $port, $callback> on it.
130		317
131	my $self = bless {	318	The block will be called for every message received on the port. When the
132	id => "$NODE#$id",	319	callback returns a true value its job is considered "done" and the port
133	names => [$id],	320	will be destroyed. Otherwise it will stay alive.
134	}, "AnyEvent::MP::Port";
135		321
136	$AnyEvent::MP::Base::PORT{$id} = sub {	322	The message will be passed as-is, no extra argument (i.e. no port id) will
137	unshift @_, $self;	323	be passed to the callback.
138		324
139	for (@{ $self->{rc0}{$_[1]} }) {	325	If you need the local port id in the callback, this works nicely:
140	$_ && &{$_->[0]}
141	&& undef $_;
142	}
143		326
144	for (@{ $self->{rcv}{$_[1]} }) {	327	my $port; $port = port {
145	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	328	snd $otherport, reply => $port;
146	&& &{$_->[0]}
147	&& undef $_;
148	}
149
150	for (@{ $self->{any} }) {
151	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
152	&& &{$_->[0]}
153	&& undef $_;
154	}
155	};	329	};
156		330
157	$self	331	=cut
		332
		333	sub rcv($@);
		334
		335	sub port(;&) {
		336	my $id = "$UNIQ." . $ID++;
		337	my $port = "$NODE#$id";
		338
		339	if (@_) {
		340	rcv $port, shift;
		341	} else {
		342	$PORT{$id} = sub { }; # nop
		343	}
		344
		345	$port
158	}	346	}
159		347
160	package AnyEvent::MP::Port;	348	=item reg $port, $name
161		349
162	=back	350	=item reg $name
163		351
164	=head1 METHODS FOR PORT OBJECTS	352	Registers the given port (or C<$SELF><<< if missing) under the name
		353	C<$name>. If the name already exists it is replaced.
165		354
166	=over 4	355	A port can only be registered under one well known name.
167		356
168	=item "$port"	357	A port automatically becomes unregistered when it is killed.
169		358
170	A port object stringifies to its port ID, so can be used directly for
171	C<snd> operations.
172
173	=cut	359	=cut
174		360
175	use overload	361	sub reg(@) {
176	'""' => sub { $_[0]{id} },	362	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
177	fallback => 1;
178		363
179	=item $port->rcv (type => $callback->($port, @msg))	364	$REG{$_[0]} = $port;
		365	}
180		366
181	=item $port->rcv ($smartmatch => $callback->($port, @msg))	367	=item rcv $port, $callback->(@msg)
182		368
		369	Replaces the callback on the specified miniport (after converting it to
		370	one if required).
		371
		372	=item rcv $port, tagstring => $callback->(@msg), ...
		373
		374	=item rcv $port, $smartmatch => $callback->(@msg), ...
		375
183	=item $port->rcv ([$smartmatch...] => $callback->($port, @msg))	376	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
184		377
185	Register a callback on the given port.	378	Register callbacks to be called on matching messages on the given full
		379	port (after converting it to one if required) and return the port.
186		380
187	The callback has to return a true value when its work is done, after	381	The callback has to return a true value when its work is done, after
188	which is will be removed, or a false value in which case it will stay	382	which is will be removed, or a false value in which case it will stay
189	registered.	383	registered.
190		384
		385	The global C<$SELF> (exported by this module) contains C<$port> while
		386	executing the callback.
		387
		388	Runtime errors during callback execution will result in the port being
		389	C<kil>ed.
		390
191	If the match is an array reference, then it will be matched against the	391	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	392	first elements of the message, otherwise only the first element is being
193	matched.	393	matched.
194		394
195	Any element in the match that is specified as C<_any_> (a function	395	Any element in the match that is specified as C<_any_> (a function
…		…
197		397
198	While not required, it is highly recommended that the first matching	398	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	399	element is a string identifying the message. The one-string-only match is
200	also the most efficient match (by far).	400	also the most efficient match (by far).
201		401
		402	Example: create a port and bind receivers on it in one go.
		403
		404	my $port = rcv port,
		405	msg1 => sub { ...; 0 },
		406	msg2 => sub { ...; 0 },
		407	;
		408
		409	Example: create a port, bind receivers and send it in a message elsewhere
		410	in one go:
		411
		412	snd $otherport, reply =>
		413	rcv port,
		414	msg1 => sub { ...; 0 },
		415	...
		416	;
		417
202	=cut	418	=cut
203		419
204	sub rcv($@) {	420	sub rcv($@) {
205	my ($self, $match, $cb) = @_;	421	my $port = shift;
		422	my ($noderef, $portid) = split /#/, $port, 2;
206		423
207	if (!ref $match) {	424	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
208	push @{ $self->{rc0}{$match} }, [$cb];	425	or Carp::croak "$port: rcv can only be called on local ports, caught";
209	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	426
210	my ($type, @match) = @$match;	427	if (@_ == 1) {
211	@match	428	my $cb = shift;
212	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	429	delete $PORT_DATA{$portid};
213	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	430	$PORT{$portid} = sub {
		431	local $SELF = $port;
		432	eval {
		433	&$cb
		434	and kil $port;
		435	};
		436	_self_die if $@;
		437	};
214	} else {	438	} else {
		439	my $self = $PORT_DATA{$portid} \|\|= do {
		440	my $self = bless {
		441	id => $port,
		442	}, "AnyEvent::MP::Port";
		443
		444	$PORT{$portid} = sub {
		445	local $SELF = $port;
		446
		447	eval {
		448	for (@{ $self->{rc0}{$_[0]} }) {
		449	$_ && &{$_->[0]}
		450	&& undef $_;
		451	}
		452
		453	for (@{ $self->{rcv}{$_[0]} }) {
		454	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
		455	&& &{$_->[0]}
		456	&& undef $_;
		457	}
		458
		459	for (@{ $self->{any} }) {
		460	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
		461	&& &{$_->[0]}
		462	&& undef $_;
		463	}
		464	};
		465	_self_die if $@;
		466	};
		467
		468	$self
		469	};
		470
		471	"AnyEvent::MP::Port" eq ref $self
		472	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		473
		474	while (@_) {
		475	my ($match, $cb) = splice @_, 0, 2;
		476
		477	if (!ref $match) {
		478	push @{ $self->{rc0}{$match} }, [$cb];
		479	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
		480	my ($type, @match) = @$match;
		481	@match
		482	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
		483	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
		484	} else {
215	push @{ $self->{any} }, [$cb, $match];	485	push @{ $self->{any} }, [$cb, $match];
		486	}
		487	}
		488	}
		489
		490	$port
		491	}
		492
		493	=item $closure = psub { BLOCK }
		494
		495	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		496	closure is executed, sets up the environment in the same way as in C<rcv>
		497	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		498
		499	This is useful when you register callbacks from C<rcv> callbacks:
		500
		501	rcv delayed_reply => sub {
		502	my ($delay, @reply) = @_;
		503	my $timer = AE::timer $delay, 0, psub {
		504	snd @reply, $SELF;
		505	};
		506	};
		507
		508	=cut
		509
		510	sub psub(&) {
		511	my $cb = shift;
		512
		513	my $port = $SELF
		514	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		515
		516	sub {
		517	local $SELF = $port;
		518
		519	if (wantarray) {
		520	my @res = eval { &$cb };
		521	_self_die if $@;
		522	@res
		523	} else {
		524	my $res = eval { &$cb };
		525	_self_die if $@;
		526	$res
		527	}
216	}	528	}
217	}	529	}
218		530
219	=item $port->register ($name)	531	=item $guard = mon $port, $cb->(@reason)
220		532
221	Registers the given port under the well known name C<$name>. If the name	533	=item $guard = mon $port, $rcvport
222	already exists it is replaced.
223		534
224	A port can only be registered under one well known name.	535	=item $guard = mon $port
225		536
226	=cut	537	=item $guard = mon $port, $rcvport, @msg
227		538
228	sub register {	539	Monitor the given port and do something when the port is killed or
229	my ($self, $name) = @_;	540	messages to it were lost, and optionally return a guard that can be used
		541	to stop monitoring again.
230		542
231	$self->{wkname} = $name;	543	C<mon> effectively guarantees that, in the absence of hardware failures,
232	$AnyEvent::MP::Base::WKP{$name} = "$self";	544	that after starting the monitor, either all messages sent to the port
		545	will arrive, or the monitoring action will be invoked after possible
		546	message loss has been detected. No messages will be lost "in between"
		547	(after the first lost message no further messages will be received by the
		548	port). After the monitoring action was invoked, further messages might get
		549	delivered again.
		550
		551	In the first form (callback), the callback is simply called with any
		552	number of C<@reason> elements (no @reason means that the port was deleted
		553	"normally"). Note also that I<< the callback B<must> never die >>, so use
		554	C<eval> if unsure.
		555
		556	In the second form (another port given), the other port (C<$rcvport>)
		557	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
		558	"normal" kils nothing happens, while under all other conditions, the other
		559	port is killed with the same reason.
		560
		561	The third form (kill self) is the same as the second form, except that
		562	C<$rvport> defaults to C<$SELF>.
		563
		564	In the last form (message), a message of the form C<@msg, @reason> will be
		565	C<snd>.
		566
		567	As a rule of thumb, monitoring requests should always monitor a port from
		568	a local port (or callback). The reason is that kill messages might get
		569	lost, just like any other message. Another less obvious reason is that
		570	even monitoring requests can get lost (for exmaple, when the connection
		571	to the other node goes down permanently). When monitoring a port locally
		572	these problems do not exist.
		573
		574	Example: call a given callback when C<$port> is killed.
		575
		576	mon $port, sub { warn "port died because of <@_>\n" };
		577
		578	Example: kill ourselves when C<$port> is killed abnormally.
		579
		580	mon $port;
		581
		582	Example: send us a restart message when another C<$port> is killed.
		583
		584	mon $port, $self => "restart";
		585
		586	=cut
		587
		588	sub mon {
		589	my ($noderef, $port) = split /#/, shift, 2;
		590
		591	my $node = $NODE{$noderef} \|\| add_node $noderef;
		592
		593	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		594
		595	unless (ref $cb) {
		596	if (@_) {
		597	# send a kill info message
		598	my (@msg) = ($cb, @_);
		599	$cb = sub { snd @msg, @_ };
		600	} else {
		601	# simply kill other port
		602	my $port = $cb;
		603	$cb = sub { kil $port, @_ if @_ };
		604	}
		605	}
		606
		607	$node->monitor ($port, $cb);
		608
		609	defined wantarray
		610	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
233	}	611	}
234		612
235	=item $port->destroy	613	=item $guard = mon_guard $port, $ref, $ref...
236		614
237	Explicitly destroy/remove/nuke/vaporise the port.	615	Monitors the given C<$port> and keeps the passed references. When the port
		616	is killed, the references will be freed.
238		617
239	Ports are normally kept alive by there mere existance alone, and need to	618	Optionally returns a guard that will stop the monitoring.
240	be destroyed explicitly.
241		619
242	=cut	620	This function is useful when you create e.g. timers or other watchers and
		621	want to free them when the port gets killed:
243		622
244	sub destroy {	623	$port->rcv (start => sub {
245	my ($self) = @_;	624	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		625	undef $timer if 0.9 < rand;
		626	});
		627	});
246		628
247	delete $AnyEvent::MP::Base::WKP{ $self->{wkname} };	629	=cut
248		630
249	delete $AnyEvent::MP::Base::PORT{$_}	631	sub mon_guard {
250	for @{ $self->{names} };	632	my ($port, @refs) = @_;
		633
		634	#TODO: mon-less form?
		635
		636	mon $port, sub { 0 && @refs }
251	}	637	}
252		638
253	=back	639	=item kil $port[, @reason]
254		640
255	=head1 FUNCTIONS FOR NODES	641	Kill the specified port with the given C<@reason>.
256		642
257	=over 4	643	If no C<@reason> is specified, then the port is killed "normally" (linked
		644	ports will not be kileld, or even notified).
258		645
259	=item mon $noderef, $callback->($noderef, $status, $)	646	Otherwise, linked ports get killed with the same reason (second form of
		647	C<mon>, see below).
260		648
261	Monitors the given noderef.	649	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		650	will be reported as reason C<< die => $@ >>.
262		651
263	=item become_public endpoint...	652	Transport/communication errors are reported as C<< transport_error =>
		653	$message >>.
264		654
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	655	=cut
		656
		657	=item $port = spawn $node, $initfunc[, @initdata]
		658
		659	Creates a port on the node C<$node> (which can also be a port ID, in which
		660	case it's the node where that port resides).
		661
		662	The port ID of the newly created port is return immediately, and it is
		663	permissible to immediately start sending messages or monitor the port.
		664
		665	After the port has been created, the init function is
		666	called. This function must be a fully-qualified function name
		667	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		668	program, use C<::name>.
		669
		670	If the function doesn't exist, then the node tries to C<require>
		671	the package, then the package above the package and so on (e.g.
		672	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		673	exists or it runs out of package names.
		674
		675	The init function is then called with the newly-created port as context
		676	object (C<$SELF>) and the C<@initdata> values as arguments.
		677
		678	A common idiom is to pass your own port, monitor the spawned port, and
		679	in the init function, monitor the original port. This two-way monitoring
		680	ensures that both ports get cleaned up when there is a problem.
		681
		682	Example: spawn a chat server port on C<$othernode>.
		683
		684	# this node, executed from within a port context:
		685	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		686	mon $server;
		687
		688	# init function on C<$othernode>
		689	sub connect {
		690	my ($srcport) = @_;
		691
		692	mon $srcport;
		693
		694	rcv $SELF, sub {
		695	...
		696	};
		697	}
		698
		699	=cut
		700
		701	sub _spawn {
		702	my $port = shift;
		703	my $init = shift;
		704
		705	local $SELF = "$NODE#$port";
		706	eval {
		707	&{ load_func $init }
		708	};
		709	_self_die if $@;
		710	}
		711
		712	sub spawn(@) {
		713	my ($noderef, undef) = split /#/, shift, 2;
		714
		715	my $id = "$RUNIQ." . $ID++;
		716
		717	$_[0] =~ /::/
		718	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		719
		720	($NODE{$noderef} \|\| add_node $noderef)
		721	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
		722
		723	"$noderef#$id"
		724	}
277		725
278	=back	726	=back
279		727
280	=head1 NODE MESSAGES	728	=head1 NODE MESSAGES
281		729
282	Nodes understand the following messages sent to them. Many of them take	730	Nodes understand the following messages sent to them. Many of them take
283	arguments called C<@reply>, which will simply be used to compose a reply	731	arguments called C<@reply>, which will simply be used to compose a reply
284	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and	732	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
285	the remaining arguments are simply the message data.	733	the remaining arguments are simply the message data.
286		734
		735	While other messages exist, they are not public and subject to change.
		736
287	=over 4	737	=over 4
288		738
289	=cut	739	=cut
290		740
291	=item wkp => $name, @reply	741	=item lookup => $name, @reply
292		742
293	Replies with the port ID of the specified well-known port, or C<undef>.	743	Replies with the port ID of the specified well-known port, or C<undef>.
294		744
295	=item devnull => ...	745	=item devnull => ...
296		746
…		…
319	snd $NODE, time => $myport, timereply => 1, 2;	769	snd $NODE, time => $myport, timereply => 1, 2;
320	# => snd $myport, timereply => 1, 2, <time>	770	# => snd $myport, timereply => 1, 2, <time>
321		771
322	=back	772	=back
323		773
		774	=head1 AnyEvent::MP vs. Distributed Erlang
		775
		776	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		777	== aemp node, Erlang process == aemp port), so many of the documents and
		778	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		779	sample:
		780
		781	http://www.Erlang.se/doc/programming_rules.shtml
		782	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		783	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		784	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		785
		786	Despite the similarities, there are also some important differences:
		787
		788	=over 4
		789
		790	=item * Node references contain the recipe on how to contact them.
		791
		792	Erlang relies on special naming and DNS to work everywhere in the
		793	same way. AEMP relies on each node knowing it's own address(es), with
		794	convenience functionality.
		795
		796	This means that AEMP requires a less tightly controlled environment at the
		797	cost of longer node references and a slightly higher management overhead.
		798
		799	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		800
		801	Erlang uses processes that selctively receive messages, and therefore
		802	needs a queue. AEMP is event based, queuing messages would serve no useful
		803	purpose.
		804
		805	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		806
		807	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		808
		809	Sending messages in Erlang is synchronous and blocks the process. AEMP
		810	sends are immediate, connection establishment is handled in the
		811	background.
		812
		813	=item * Erlang can silently lose messages, AEMP cannot.
		814
		815	Erlang makes few guarantees on messages delivery - messages can get lost
		816	without any of the processes realising it (i.e. you send messages a, b,
		817	and c, and the other side only receives messages a and c).
		818
		819	AEMP guarantees correct ordering, and the guarantee that there are no
		820	holes in the message sequence.
		821
		822	=item * In Erlang, processes can be declared dead and later be found to be
		823	alive.
		824
		825	In Erlang it can happen that a monitored process is declared dead and
		826	linked processes get killed, but later it turns out that the process is
		827	still alive - and can receive messages.
		828
		829	In AEMP, when port monitoring detects a port as dead, then that port will
		830	eventually be killed - it cannot happen that a node detects a port as dead
		831	and then later sends messages to it, finding it is still alive.
		832
		833	=item * Erlang can send messages to the wrong port, AEMP does not.
		834
		835	In Erlang it is quite possible that a node that restarts reuses a process
		836	ID known to other nodes for a completely different process, causing
		837	messages destined for that process to end up in an unrelated process.
		838
		839	AEMP never reuses port IDs, so old messages or old port IDs floating
		840	around in the network will not be sent to an unrelated port.
		841
		842	=item * Erlang uses unprotected connections, AEMP uses secure
		843	authentication and can use TLS.
		844
		845	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		846	securely authenticate nodes.
		847
		848	=item * The AEMP protocol is optimised for both text-based and binary
		849	communications.
		850
		851	The AEMP protocol, unlike the Erlang protocol, supports both
		852	language-independent text-only protocols (good for debugging) and binary,
		853	language-specific serialisers (e.g. Storable).
		854
		855	It has also been carefully designed to be implementable in other languages
		856	with a minimum of work while gracefully degrading fucntionality to make the
		857	protocol simple.
		858
		859	=item * AEMP has more flexible monitoring options than Erlang.
		860
		861	In Erlang, you can chose to receive I<all> exit signals as messages
		862	or I<none>, there is no in-between, so monitoring single processes is
		863	difficult to implement. Monitoring in AEMP is more flexible than in
		864	Erlang, as one can choose between automatic kill, exit message or callback
		865	on a per-process basis.
		866
		867	=item * Erlang tries to hide remote/local connections, AEMP does not.
		868
		869	Monitoring in Erlang is not an indicator of process death/crashes,
		870	as linking is (except linking is unreliable in Erlang).
		871
		872	In AEMP, you don't "look up" registered port names or send to named ports
		873	that might or might not be persistent. Instead, you normally spawn a port
		874	on the remote node. The init function monitors the you, and you monitor
		875	the remote port. Since both monitors are local to the node, they are much
		876	more reliable.
		877
		878	This also saves round-trips and avoids sending messages to the wrong port
		879	(hard to do in Erlang).
		880
		881	=back
		882
		883	=head1 RATIONALE
		884
		885	=over 4
		886
		887	=item Why strings for ports and noderefs, why not objects?
		888
		889	We considered "objects", but found that the actual number of methods
		890	thatc an be called are very low. Since port IDs and noderefs travel over
		891	the network frequently, the serialising/deserialising would add lots of
		892	overhead, as well as having to keep a proxy object.
		893
		894	Strings can easily be printed, easily serialised etc. and need no special
		895	procedures to be "valid".
		896
		897	And a a miniport consists of a single closure stored in a global hash - it
		898	can't become much cheaper.
		899
		900	=item Why favour JSON, why not real serialising format such as Storable?
		901
		902	In fact, any AnyEvent::MP node will happily accept Storable as framing
		903	format, but currently there is no way to make a node use Storable by
		904	default.
		905
		906	The default framing protocol is JSON because a) JSON::XS is many times
		907	faster for small messages and b) most importantly, after years of
		908	experience we found that object serialisation is causing more problems
		909	than it gains: Just like function calls, objects simply do not travel
		910	easily over the network, mostly because they will always be a copy, so you
		911	always have to re-think your design.
		912
		913	Keeping your messages simple, concentrating on data structures rather than
		914	objects, will keep your messages clean, tidy and efficient.
		915
		916	=back
		917
324	=head1 SEE ALSO	918	=head1 SEE ALSO
325		919
326	L<AnyEvent>.	920	L<AnyEvent>.
327		921
328	=head1 AUTHOR	922	=head1 AUTHOR

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Revision 1.49 by root, Thu Aug 13 15:29:58 2009 UTC