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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.22 by root, Tue Aug 4 18:33:30 2009 UTC vs.
Revision 1.62 by root, Thu Aug 27 07:12:48 2009 UTC

…		…
8		8
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		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
13	snd $port, type => data...;	23	snd $port, type => data...;
		24	snd $port, @msg;
		25	snd @msg_with_first_element_being_a_port;
14		26
15	$SELF # receiving/own port id in rcv callbacks	27	# creating/using ports, the simple way
		28	my $simple_port = port { my @msg = @_; 0 };
16		29
17	rcv $port, smartmatch => $cb->($port, @msg);	30	# creating/using ports, tagged message matching
18		31	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
21	rcv $port1, pong => sub { warn "pong received\n" };	33	rcv $port, pong => sub { warn "pong received\n"; 0 };
22	snd $port2, ping => $port1;
23		34
24	# more, smarter, matches (_any_ is exported by this module)	35	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	36	my $port = spawn $node, $initfunc, @initdata;
26	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		46	AnyEvent::MP::Intro - outdated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.
27		51
28	=head1 DESCRIPTION	52	=head1 DESCRIPTION
29		53
30	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
31		55
32	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
33	on the same or other hosts.	57	on the same or other hosts.
34		58
		59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
		60	manual page.
		61
35	At the moment, this module family is severly brokena nd underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
36	so do not use. This was uploaded mainly to reserve the CPAN namespace -	63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
37	stay tuned!	64	stay tuned!
38		65
39	=head1 CONCEPTS	66	=head1 CONCEPTS
40		67
41	=over 4	68	=over 4
42		69
43	=item port	70	=item port
44		71
45	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).
46	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
47	messages they match, messages will not be queued.	75	some messages. Messages will not be queued.
48		76
49	=item port id - C<noderef#portname>	77	=item port id - C<noderef#portname>
50		78
51	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
52	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.
53		83
54	=item node	84	=item node
55		85
56	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,
57	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
58	among other things.	88	ports.
59		89
60	Initially, nodes are either private (single-process only) or hidden	90	Nodes are either private (single-process only), slaves (can only talk to
61	(connected to a master node only). Only when they epxlicitly "become	91	public nodes, but do not need an open port) or public nodes (connectable
62	public" can you send them messages from unrelated other nodes.	92	from any other node).
63		93
64	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	94	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
65		95
66	A noderef is a string that either uniquely identifies a given node (for	96	A node reference is a string that either simply identifies the node (for
67	private and hidden nodes), or contains a recipe on how to reach a given	97	private and slave nodes), or contains a recipe on how to reach a given
68	node (for public nodes).	98	node (for public nodes).
69		99
		100	This recipe is simply a comma-separated list of C<address:port> pairs (for
		101	TCP/IP, other protocols might look different).
		102
		103	Node references come in two flavours: resolved (containing only numerical
		104	addresses) or unresolved (where hostnames are used instead of addresses).
		105
		106	Before using an unresolved node reference in a message you first have to
		107	resolve it.
		108
70	=back	109	=back
71		110
72	=head1 VARIABLES/FUNCTIONS	111	=head1 VARIABLES/FUNCTIONS
73		112
74	=over 4	113	=over 4
75		114
76	=cut	115	=cut
77		116
78	package AnyEvent::MP;	117	package AnyEvent::MP;
79		118
80	use AnyEvent::MP::Base;	119	use AnyEvent::MP::Kernel;
81		120
82	use common::sense;	121	use common::sense;
83		122
84	use Carp ();	123	use Carp ();
85		124
86	use AE ();	125	use AE ();
87		126
88	use base "Exporter";	127	use base "Exporter";
89		128
90	our $VERSION = '0.02';	129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		130
91	our @EXPORT = qw(	131	our @EXPORT = qw(
92	NODE $NODE *SELF node_of _any_	132	NODE $NODE *SELF node_of after
93	become_slave become_public	133	resolve_node initialise_node
94	snd rcv mon kil reg psub	134	snd rcv mon mon_guard kil reg psub spawn
95	port	135	port
96	);	136	);
97		137
98	our $SELF;	138	our $SELF;
99		139
…		…
103	kil $SELF, die => $msg;	143	kil $SELF, die => $msg;
104	}	144	}
105		145
106	=item $thisnode = NODE / $NODE	146	=item $thisnode = NODE / $NODE
107		147
108	The C<NODE> function returns, and the C<$NODE> variable contains	148	The C<NODE> function returns, and the C<$NODE> variable contains the
109	the noderef of the local node. The value is initialised by a call	149	noderef of the local node. The value is initialised by a call to
110	to C<become_public> or C<become_slave>, after which all local port	150	C<initialise_node>.
111	identifiers become invalid.
112		151
113	=item $noderef = node_of $portid	152	=item $noderef = node_of $port
114		153
115	Extracts and returns the noderef from a portid or a noderef.	154	Extracts and returns the noderef from a port ID or a noderef.
		155
		156	=item initialise_node $noderef, $seednode, $seednode...
		157
		158	=item initialise_node "slave/", $master, $master...
		159
		160	Before a node can talk to other nodes on the network it has to initialise
		161	itself - the minimum a node needs to know is it's own name, and optionally
		162	it should know the noderefs of some other nodes in the network.
		163
		164	This function initialises a node - it must be called exactly once (or
		165	never) before calling other AnyEvent::MP functions.
		166
		167	All arguments (optionally except for the first) are noderefs, which can be
		168	either resolved or unresolved.
		169
		170	The first argument will be looked up in the configuration database first
		171	(if it is C<undef> then the current nodename will be used instead) to find
		172	the relevant configuration profile (see L<aemp>). If none is found then
		173	the default configuration is used. The configuration supplies additional
		174	seed/master nodes and can override the actual noderef.
		175
		176	There are two types of networked nodes, public nodes and slave nodes:
		177
		178	=over 4
		179
		180	=item public nodes
		181
		182	For public nodes, C<$noderef> (supplied either directly to
		183	C<initialise_node> or indirectly via a profile or the nodename) must be a
		184	noderef (possibly unresolved, in which case it will be resolved).
		185
		186	After resolving, the node will bind itself on all endpoints.
		187
		188	=item slave nodes
		189
		190	When the C<$noderef> (either as given or overriden by the config file)
		191	is the special string C<slave/>, then the node will become a slave
		192	node. Slave nodes cannot be contacted from outside, and cannot talk to
		193	each other (at least in this version of AnyEvent::MP).
		194
		195	Slave nodes work by creating connections to all public nodes, using the
		196	L<AnyEvent::MP::Global> service.
		197
		198	=back
		199
		200	After initialising itself, the node will connect to all additional
		201	C<$seednodes> that are specified diretcly or via a profile. Seednodes are
		202	optional and can be used to quickly bootstrap the node into an existing
		203	network.
		204
		205	All the seednodes will also be specially marked to automatically retry
		206	connecting to them indefinitely, so make sure that seednodes are really
		207	reliable and up (this might also change in the future).
		208
		209	Example: become a public node listening on the guessed noderef, or the one
		210	specified via C<aemp> for the current node. This should be the most common
		211	form of invocation for "daemon"-type nodes.
		212
		213	initialise_node;
		214
		215	Example: become a slave node to any of the the seednodes specified via
		216	C<aemp>. This form is often used for commandline clients.
		217
		218	initialise_node "slave/";
		219
		220	Example: become a public node, and try to contact some well-known master
		221	servers to become part of the network.
		222
		223	initialise_node undef, "master1", "master2";
		224
		225	Example: become a public node listening on port C<4041>.
		226
		227	initialise_node 4041;
		228
		229	Example: become a public node, only visible on localhost port 4044.
		230
		231	initialise_node "localhost:4044";
		232
		233	=item $cv = resolve_node $noderef
		234
		235	Takes an unresolved node reference that may contain hostnames and
		236	abbreviated IDs, resolves all of them and returns a resolved node
		237	reference.
		238
		239	In addition to C<address:port> pairs allowed in resolved noderefs, the
		240	following forms are supported:
		241
		242	=over 4
		243
		244	=item the empty string
		245
		246	An empty-string component gets resolved as if the default port (4040) was
		247	specified.
		248
		249	=item naked port numbers (e.g. C<1234>)
		250
		251	These are resolved by prepending the local nodename and a colon, to be
		252	further resolved.
		253
		254	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
		255
		256	These are resolved by using AnyEvent::DNS to resolve them, optionally
		257	looking up SRV records for the C<aemp=4040> port, if no port was
		258	specified.
		259
		260	=back
116		261
117	=item $SELF	262	=item $SELF
118		263
119	Contains the current port id while executing C<rcv> callbacks or C<psub>	264	Contains the current port id while executing C<rcv> callbacks or C<psub>
120	blocks.	265	blocks.
…		…
123		268
124	Due to some quirks in how perl exports variables, it is impossible to	269	Due to some quirks in how perl exports variables, it is impossible to
125	just export C<$SELF>, all the symbols called C<SELF> are exported by this	270	just export C<$SELF>, all the symbols called C<SELF> are exported by this
126	module, but only C<$SELF> is currently used.	271	module, but only C<$SELF> is currently used.
127		272
128	=item snd $portid, type => @data	273	=item snd $port, type => @data
129		274
130	=item snd $portid, @msg	275	=item snd $port, @msg
131		276
132	Send the given message to the given port ID, which can identify either	277	Send the given message to the given port ID, which can identify either
133	a local or a remote port, and can be either a string or soemthignt hat	278	a local or a remote port, and must be a port ID.
134	stringifies a sa port ID (such as a port object :).
135		279
136	While the message can be about anything, it is highly recommended to use a	280	While the message can be about anything, it is highly recommended to use a
137	string as first element (a portid, or some word that indicates a request	281	string as first element (a port ID, or some word that indicates a request
138	type etc.).	282	type etc.).
139		283
140	The message data effectively becomes read-only after a call to this	284	The message data effectively becomes read-only after a call to this
141	function: modifying any argument is not allowed and can cause many	285	function: modifying any argument is not allowed and can cause many
142	problems.	286	problems.
…		…
145	JSON is used, then only strings, numbers and arrays and hashes consisting	289	JSON is used, then only strings, numbers and arrays and hashes consisting
146	of those are allowed (no objects). When Storable is used, then anything	290	of those are allowed (no objects). When Storable is used, then anything
147	that Storable can serialise and deserialise is allowed, and for the local	291	that Storable can serialise and deserialise is allowed, and for the local
148	node, anything can be passed.	292	node, anything can be passed.
149		293
150	=item kil $portid[, @reason]	294	=item $local_port = port
151		295
152	Kill the specified port with the given C<@reason>.	296	Create a new local port object and returns its port ID. Initially it has
		297	no callbacks set and will throw an error when it receives messages.
153		298
154	If no C<@reason> is specified, then the port is killed "normally" (linked	299	=item $local_port = port { my @msg = @_ }
155	ports will not be kileld, or even notified).
156		300
157	Otherwise, linked ports get killed with the same reason (second form of	301	Creates a new local port, and returns its ID. Semantically the same as
158	C<mon>, see below).	302	creating a port and calling C<rcv $port, $callback> on it.
159		303
160	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	304	The block will be called for every message received on the port, with the
161	will be reported as reason C<< die => $@ >>.	305	global variable C<$SELF> set to the port ID. Runtime errors will cause the
		306	port to be C<kil>ed. The message will be passed as-is, no extra argument
		307	(i.e. no port ID) will be passed to the callback.
162		308
163	Transport/communication errors are reported as C<< transport_error =>	309	If you want to stop/destroy the port, simply C<kil> it:
164	$message >>.
165		310
		311	my $port = port {
		312	my @msg = @_;
		313	...
		314	kil $SELF;
		315	};
		316
		317	=cut
		318
		319	sub rcv($@);
		320
		321	sub _kilme {
		322	die "received message on port without callback";
		323	}
		324
		325	sub port(;&) {
		326	my $id = "$UNIQ." . $ID++;
		327	my $port = "$NODE#$id";
		328
		329	rcv $port, shift \|\| \&_kilme;
		330
		331	$port
		332	}
		333
		334	=item rcv $local_port, $callback->(@msg)
		335
		336	Replaces the default callback on the specified port. There is no way to
		337	remove the default callback: use C<sub { }> to disable it, or better
		338	C<kil> the port when it is no longer needed.
		339
		340	The global C<$SELF> (exported by this module) contains C<$port> while
		341	executing the callback. Runtime errors during callback execution will
		342	result in the port being C<kil>ed.
		343
		344	The default callback received all messages not matched by a more specific
		345	C<tag> match.
		346
		347	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
		348
		349	Register (or replace) callbacks to be called on messages starting with the
		350	given tag on the given port (and return the port), or unregister it (when
		351	C<$callback> is C<$undef> or missing). There can only be one callback
		352	registered for each tag.
		353
		354	The original message will be passed to the callback, after the first
		355	element (the tag) has been removed. The callback will use the same
		356	environment as the default callback (see above).
		357
		358	Example: create a port and bind receivers on it in one go.
		359
		360	my $port = rcv port,
		361	msg1 => sub { ... },
		362	msg2 => sub { ... },
		363	;
		364
		365	Example: create a port, bind receivers and send it in a message elsewhere
		366	in one go:
		367
		368	snd $otherport, reply =>
		369	rcv port,
		370	msg1 => sub { ... },
		371	...
		372	;
		373
		374	Example: temporarily register a rcv callback for a tag matching some port
		375	(e.g. for a rpc reply) and unregister it after a message was received.
		376
		377	rcv $port, $otherport => sub {
		378	my @reply = @_;
		379
		380	rcv $SELF, $otherport;
		381	};
		382
		383	=cut
		384
		385	sub rcv($@) {
		386	my $port = shift;
		387	my ($noderef, $portid) = split /#/, $port, 2;
		388
		389	$NODE{$noderef} == $NODE{""}
		390	or Carp::croak "$port: rcv can only be called on local ports, caught";
		391
		392	while (@_) {
		393	if (ref $_[0]) {
		394	if (my $self = $PORT_DATA{$portid}) {
		395	"AnyEvent::MP::Port" eq ref $self
		396	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		397
		398	$self->[2] = shift;
		399	} else {
		400	my $cb = shift;
		401	$PORT{$portid} = sub {
		402	local $SELF = $port;
		403	eval { &$cb }; _self_die if $@;
		404	};
		405	}
		406	} elsif (defined $_[0]) {
		407	my $self = $PORT_DATA{$portid} \|\|= do {
		408	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
		409
		410	$PORT{$portid} = sub {
		411	local $SELF = $port;
		412
		413	if (my $cb = $self->[1]{$_[0]}) {
		414	shift;
		415	eval { &$cb }; _self_die if $@;
		416	} else {
		417	&{ $self->[0] };
		418	}
		419	};
		420
		421	$self
		422	};
		423
		424	"AnyEvent::MP::Port" eq ref $self
		425	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		426
		427	my ($tag, $cb) = splice @_, 0, 2;
		428
		429	if (defined $cb) {
		430	$self->[1]{$tag} = $cb;
		431	} else {
		432	delete $self->[1]{$tag};
		433	}
		434	}
		435	}
		436
		437	$port
		438	}
		439
		440	=item $closure = psub { BLOCK }
		441
		442	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
		443	closure is executed, sets up the environment in the same way as in C<rcv>
		444	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		445
		446	This is useful when you register callbacks from C<rcv> callbacks:
		447
		448	rcv delayed_reply => sub {
		449	my ($delay, @reply) = @_;
		450	my $timer = AE::timer $delay, 0, psub {
		451	snd @reply, $SELF;
		452	};
		453	};
		454
		455	=cut
		456
		457	sub psub(&) {
		458	my $cb = shift;
		459
		460	my $port = $SELF
		461	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
		462
		463	sub {
		464	local $SELF = $port;
		465
		466	if (wantarray) {
		467	my @res = eval { &$cb };
		468	_self_die if $@;
		469	@res
		470	} else {
		471	my $res = eval { &$cb };
		472	_self_die if $@;
		473	$res
		474	}
		475	}
		476	}
		477
166	=item $guard = mon $portid, $cb->(@reason)	478	=item $guard = mon $port, $cb->(@reason)
167		479
168	=item $guard = mon $portid, $otherport	480	=item $guard = mon $port, $rcvport
169		481
		482	=item $guard = mon $port
		483
170	=item $guard = mon $portid, $otherport, @msg	484	=item $guard = mon $port, $rcvport, @msg
171		485
172	Monitor the given port and do something when the port is killed.	486	Monitor the given port and do something when the port is killed or
		487	messages to it were lost, and optionally return a guard that can be used
		488	to stop monitoring again.
173		489
		490	C<mon> effectively guarantees that, in the absence of hardware failures,
		491	that after starting the monitor, either all messages sent to the port
		492	will arrive, or the monitoring action will be invoked after possible
		493	message loss has been detected. No messages will be lost "in between"
		494	(after the first lost message no further messages will be received by the
		495	port). After the monitoring action was invoked, further messages might get
		496	delivered again.
		497
		498	Note that monitoring-actions are one-shot: once released, they are removed
		499	and will not trigger again.
		500
174	In the first form, the callback is simply called with any number	501	In the first form (callback), the callback is simply called with any
175	of C<@reason> elements (no @reason means that the port was deleted	502	number of C<@reason> elements (no @reason means that the port was deleted
176	"normally"). Note also that I<< the callback B<must> never die >>, so use	503	"normally"). Note also that I<< the callback B<must> never die >>, so use
177	C<eval> if unsure.	504	C<eval> if unsure.
178		505
179	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	506	In the second form (another port given), the other port (C<$rcvport>)
180	a @reason was specified, i.e. on "normal" kils nothing happens, while	507	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
181	under all other conditions, the other port is killed with the same reason.	508	"normal" kils nothing happens, while under all other conditions, the other
		509	port is killed with the same reason.
182		510
		511	The third form (kill self) is the same as the second form, except that
		512	C<$rvport> defaults to C<$SELF>.
		513
183	In the last form, a message of the form C<@msg, @reason> will be C<snd>.	514	In the last form (message), a message of the form C<@msg, @reason> will be
		515	C<snd>.
		516
		517	As a rule of thumb, monitoring requests should always monitor a port from
		518	a local port (or callback). The reason is that kill messages might get
		519	lost, just like any other message. Another less obvious reason is that
		520	even monitoring requests can get lost (for exmaple, when the connection
		521	to the other node goes down permanently). When monitoring a port locally
		522	these problems do not exist.
184		523
185	Example: call a given callback when C<$port> is killed.	524	Example: call a given callback when C<$port> is killed.
186		525
187	mon $port, sub { warn "port died because of <@_>\n" };	526	mon $port, sub { warn "port died because of <@_>\n" };
188		527
189	Example: kill ourselves when C<$port> is killed abnormally.	528	Example: kill ourselves when C<$port> is killed abnormally.
190		529
191	mon $port, $self;	530	mon $port;
192		531
193	Example: send us a restart message another C<$port> is killed.	532	Example: send us a restart message when another C<$port> is killed.
194		533
195	mon $port, $self => "restart";	534	mon $port, $self => "restart";
196		535
197	=cut	536	=cut
198		537
199	sub mon {	538	sub mon {
200	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	539	my ($noderef, $port) = split /#/, shift, 2;
201		540
202	my $node = $NODE{$noderef} \|\| add_node $noderef;	541	my $node = $NODE{$noderef} \|\| add_node $noderef;
203		542
204	#TODO: ports must not be references	543	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
205	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {	544
		545	unless (ref $cb) {
206	if (@_) {	546	if (@_) {
207	# send a kill info message	547	# send a kill info message
208	my (@msg) = ($cb, @_);	548	my (@msg) = ($cb, @_);
209	$cb = sub { snd @msg, @_ };	549	$cb = sub { snd @msg, @_ };
210	} else {	550	} else {
…		…
239	=cut	579	=cut
240		580
241	sub mon_guard {	581	sub mon_guard {
242	my ($port, @refs) = @_;	582	my ($port, @refs) = @_;
243		583
		584	#TODO: mon-less form?
		585
244	mon $port, sub { 0 && @refs }	586	mon $port, sub { 0 && @refs }
245	}	587	}
246		588
247	=item $local_port = port	589	=item kil $port[, @reason]
248		590
249	Create a new local port object that supports message matching.	591	Kill the specified port with the given C<@reason>.
250		592
251	=item $portid = port { my @msg = @_; $finished }	593	If no C<@reason> is specified, then the port is killed "normally" (linked
		594	ports will not be kileld, or even notified).
252		595
253	Creates a "mini port", that is, a very lightweight port without any	596	Otherwise, linked ports get killed with the same reason (second form of
254	pattern matching behind it, and returns its ID.	597	C<mon>, see below).
255		598
256	The block will be called for every message received on the port. When the	599	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
257	callback returns a true value its job is considered "done" and the port	600	will be reported as reason C<< die => $@ >>.
258	will be destroyed. Otherwise it will stay alive.
259		601
260	The message will be passed as-is, no extra argument (i.e. no port id) will	602	Transport/communication errors are reported as C<< transport_error =>
261	be passed to the callback.	603	$message >>.
262		604
263	If you need the local port id in the callback, this works nicely:
264
265	my $port; $port = miniport {
266	snd $otherport, reply => $port;
267	};
268
269	=cut	605	=cut
270		606
271	sub port(;&) {	607	=item $port = spawn $node, $initfunc[, @initdata]
272	my $id = "$UNIQ." . $ID++;
273	my $port = "$NODE#$id";
274		608
275	if (@_) {	609	Creates a port on the node C<$node> (which can also be a port ID, in which
276	my $cb = shift;	610	case it's the node where that port resides).
277	$PORT{$id} = sub {	611
278	local $SELF = $port;	612	The port ID of the newly created port is return immediately, and it is
279	eval {	613	permissible to immediately start sending messages or monitor the port.
280	&$cb	614
281	and kil $id;	615	After the port has been created, the init function is
		616	called. This function must be a fully-qualified function name
		617	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main
		618	program, use C<::name>.
		619
		620	If the function doesn't exist, then the node tries to C<require>
		621	the package, then the package above the package and so on (e.g.
		622	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		623	exists or it runs out of package names.
		624
		625	The init function is then called with the newly-created port as context
		626	object (C<$SELF>) and the C<@initdata> values as arguments.
		627
		628	A common idiom is to pass your own port, monitor the spawned port, and
		629	in the init function, monitor the original port. This two-way monitoring
		630	ensures that both ports get cleaned up when there is a problem.
		631
		632	Example: spawn a chat server port on C<$othernode>.
		633
		634	# this node, executed from within a port context:
		635	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		636	mon $server;
		637
		638	# init function on C<$othernode>
		639	sub connect {
		640	my ($srcport) = @_;
		641
		642	mon $srcport;
		643
		644	rcv $SELF, sub {
282	};	645	...
283	_self_die if $@;
284	};
285	} else {
286	my $self = bless {
287	id => "$NODE#$id",
288	}, "AnyEvent::MP::Port";
289
290	$PORT_DATA{$id} = $self;
291	$PORT{$id} = sub {
292	local $SELF = $port;
293
294	eval {
295	for (@{ $self->{rc0}{$_[0]} }) {
296	$_ && &{$_->[0]}
297	&& undef $_;
298	}
299
300	for (@{ $self->{rcv}{$_[0]} }) {
301	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
302	&& &{$_->[0]}
303	&& undef $_;
304	}
305
306	for (@{ $self->{any} }) {
307	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
308	&& &{$_->[0]}
309	&& undef $_;
310	}
311	};
312	_self_die if $@;
313	};	646	};
314	}	647	}
315		648
316	$port
317	}
318
319	=item reg $portid, $name
320
321	Registers the given port under the name C<$name>. If the name already
322	exists it is replaced.
323
324	A port can only be registered under one well known name.
325
326	A port automatically becomes unregistered when it is killed.
327
328	=cut	649	=cut
329		650
330	sub reg(@) {	651	sub _spawn {
331	my ($portid, $name) = @_;	652	my $port = shift;
		653	my $init = shift;
332		654
333	$REG{$name} = $portid;	655	local $SELF = "$NODE#$port";
334	}	656	eval {
335		657	&{ load_func $init }
336	=item rcv $portid, tagstring => $callback->(@msg), ...
337
338	=item rcv $portid, $smartmatch => $callback->(@msg), ...
339
340	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
341
342	Register callbacks to be called on matching messages on the given port.
343
344	The callback has to return a true value when its work is done, after
345	which is will be removed, or a false value in which case it will stay
346	registered.
347
348	The global C<$SELF> (exported by this module) contains C<$portid> while
349	executing the callback.
350
351	Runtime errors wdurign callback execution will result in the port being
352	C<kil>ed.
353
354	If the match is an array reference, then it will be matched against the
355	first elements of the message, otherwise only the first element is being
356	matched.
357
358	Any element in the match that is specified as C<_any_> (a function
359	exported by this module) matches any single element of the message.
360
361	While not required, it is highly recommended that the first matching
362	element is a string identifying the message. The one-string-only match is
363	also the most efficient match (by far).
364
365	=cut
366
367	sub rcv($@) {
368	my ($noderef, $port) = split /#/, shift, 2;
369
370	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
371	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
372
373	my $self = $PORT_DATA{$port}
374	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
375
376	"AnyEvent::MP::Port" eq ref $self
377	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
378
379	while (@_) {
380	my ($match, $cb) = splice @_, 0, 2;
381
382	if (!ref $match) {
383	push @{ $self->{rc0}{$match} }, [$cb];
384	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
385	my ($type, @match) = @$match;
386	@match
387	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
388	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
389	} else {
390	push @{ $self->{any} }, [$cb, $match];
391	}
392	}
393	}
394
395	=item $closure = psub { BLOCK }
396
397	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
398	closure is executed, sets up the environment in the same way as in C<rcv>
399	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
400
401	This is useful when you register callbacks from C<rcv> callbacks:
402
403	rcv delayed_reply => sub {
404	my ($delay, @reply) = @_;
405	my $timer = AE::timer $delay, 0, psub {
406	snd @reply, $SELF;
407	};
408	};	658	};
409
410	=cut
411
412	sub psub(&) {
413	my $cb = shift;
414
415	my $port = $SELF
416	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
417
418	sub {
419	local $SELF = $port;
420
421	if (wantarray) {
422	my @res = eval { &$cb };
423	_self_die if $@;	659	_self_die if $@;
424	@res	660	}
425	} else {	661
426	my $res = eval { &$cb };	662	sub spawn(@) {
427	_self_die if $@;	663	my ($noderef, undef) = split /#/, shift, 2;
428	$res	664
429	}	665	my $id = "$RUNIQ." . $ID++;
		666
		667	$_[0] =~ /::/
		668	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		669
		670	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
		671
		672	"$noderef#$id"
		673	}
		674
		675	=item after $timeout, @msg
		676
		677	=item after $timeout, $callback
		678
		679	Either sends the given message, or call the given callback, after the
		680	specified number of seconds.
		681
		682	This is simply a utility function that come sin handy at times.
		683
		684	=cut
		685
		686	sub after($@) {
		687	my ($timeout, @action) = @_;
		688
		689	my $t; $t = AE::timer $timeout, 0, sub {
		690	undef $t;
		691	ref $action[0]
		692	? $action[0]()
		693	: snd @action;
430	}	694	};
431	}	695	}
432		696
433	=back	697	=back
434		698
435	=head1 FUNCTIONS FOR NODES	699	=head1 AnyEvent::MP vs. Distributed Erlang
		700
		701	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
		702	== aemp node, Erlang process == aemp port), so many of the documents and
		703	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
		704	sample:
		705
		706	http://www.Erlang.se/doc/programming_rules.shtml
		707	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
		708	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
		709	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
		710
		711	Despite the similarities, there are also some important differences:
436		712
437	=over 4	713	=over 4
438		714
439	=item become_public endpoint...	715	=item * Node references contain the recipe on how to contact them.
440		716
441	Tells the node to become a public node, i.e. reachable from other nodes.	717	Erlang relies on special naming and DNS to work everywhere in the
		718	same way. AEMP relies on each node knowing it's own address(es), with
		719	convenience functionality.
442		720
443	If no arguments are given, or the first argument is C<undef>, then	721	This means that AEMP requires a less tightly controlled environment at the
444	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the	722	cost of longer node references and a slightly higher management overhead.
445	local nodename resolves to.
446		723
447	Otherwise the first argument must be an array-reference with transport	724	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
448	endpoints ("ip:port", "hostname:port") or port numbers (in which case the	725	uses "local ports are like remote ports".
449	local nodename is used as hostname). The endpoints are all resolved and
450	will become the node reference.
451		726
452	=cut	727	The failure modes for local ports are quite different (runtime errors
		728	only) then for remote ports - when a local port dies, you I<know> it dies,
		729	when a connection to another node dies, you know nothing about the other
		730	port.
		731
		732	Erlang pretends remote ports are as reliable as local ports, even when
		733	they are not.
		734
		735	AEMP encourages a "treat remote ports differently" philosophy, with local
		736	ports being the special case/exception, where transport errors cannot
		737	occur.
		738
		739	=item * Erlang uses processes and a mailbox, AEMP does not queue.
		740
		741	Erlang uses processes that selectively receive messages, and therefore
		742	needs a queue. AEMP is event based, queuing messages would serve no
		743	useful purpose. For the same reason the pattern-matching abilities of
		744	AnyEvent::MP are more limited, as there is little need to be able to
		745	filter messages without dequeing them.
		746
		747	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
		748
		749	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
		750
		751	Sending messages in Erlang is synchronous and blocks the process (and
		752	so does not need a queue that can overflow). AEMP sends are immediate,
		753	connection establishment is handled in the background.
		754
		755	=item * Erlang suffers from silent message loss, AEMP does not.
		756
		757	Erlang makes few guarantees on messages delivery - messages can get lost
		758	without any of the processes realising it (i.e. you send messages a, b,
		759	and c, and the other side only receives messages a and c).
		760
		761	AEMP guarantees correct ordering, and the guarantee that there are no
		762	holes in the message sequence.
		763
		764	=item * In Erlang, processes can be declared dead and later be found to be
		765	alive.
		766
		767	In Erlang it can happen that a monitored process is declared dead and
		768	linked processes get killed, but later it turns out that the process is
		769	still alive - and can receive messages.
		770
		771	In AEMP, when port monitoring detects a port as dead, then that port will
		772	eventually be killed - it cannot happen that a node detects a port as dead
		773	and then later sends messages to it, finding it is still alive.
		774
		775	=item * Erlang can send messages to the wrong port, AEMP does not.
		776
		777	In Erlang it is quite likely that a node that restarts reuses a process ID
		778	known to other nodes for a completely different process, causing messages
		779	destined for that process to end up in an unrelated process.
		780
		781	AEMP never reuses port IDs, so old messages or old port IDs floating
		782	around in the network will not be sent to an unrelated port.
		783
		784	=item * Erlang uses unprotected connections, AEMP uses secure
		785	authentication and can use TLS.
		786
		787	AEMP can use a proven protocol - SSL/TLS - to protect connections and
		788	securely authenticate nodes.
		789
		790	=item * The AEMP protocol is optimised for both text-based and binary
		791	communications.
		792
		793	The AEMP protocol, unlike the Erlang protocol, supports both
		794	language-independent text-only protocols (good for debugging) and binary,
		795	language-specific serialisers (e.g. Storable).
		796
		797	It has also been carefully designed to be implementable in other languages
		798	with a minimum of work while gracefully degrading fucntionality to make the
		799	protocol simple.
		800
		801	=item * AEMP has more flexible monitoring options than Erlang.
		802
		803	In Erlang, you can chose to receive I<all> exit signals as messages
		804	or I<none>, there is no in-between, so monitoring single processes is
		805	difficult to implement. Monitoring in AEMP is more flexible than in
		806	Erlang, as one can choose between automatic kill, exit message or callback
		807	on a per-process basis.
		808
		809	=item * Erlang tries to hide remote/local connections, AEMP does not.
		810
		811	Monitoring in Erlang is not an indicator of process death/crashes,
		812	as linking is (except linking is unreliable in Erlang).
		813
		814	In AEMP, you don't "look up" registered port names or send to named ports
		815	that might or might not be persistent. Instead, you normally spawn a port
		816	on the remote node. The init function monitors the you, and you monitor
		817	the remote port. Since both monitors are local to the node, they are much
		818	more reliable.
		819
		820	This also saves round-trips and avoids sending messages to the wrong port
		821	(hard to do in Erlang).
453		822
454	=back	823	=back
455		824
456	=head1 NODE MESSAGES	825	=head1 RATIONALE
457
458	Nodes understand the following messages sent to them. Many of them take
459	arguments called C<@reply>, which will simply be used to compose a reply
460	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
461	the remaining arguments are simply the message data.
462		826
463	=over 4	827	=over 4
464		828
465	=cut	829	=item Why strings for ports and noderefs, why not objects?
466		830
467	=item lookup => $name, @reply	831	We considered "objects", but found that the actual number of methods
		832	thatc an be called are very low. Since port IDs and noderefs travel over
		833	the network frequently, the serialising/deserialising would add lots of
		834	overhead, as well as having to keep a proxy object.
468		835
469	Replies with the port ID of the specified well-known port, or C<undef>.	836	Strings can easily be printed, easily serialised etc. and need no special
		837	procedures to be "valid".
470		838
471	=item devnull => ...	839	And a a miniport consists of a single closure stored in a global hash - it
		840	can't become much cheaper.
472		841
473	Generic data sink/CPU heat conversion.	842	=item Why favour JSON, why not real serialising format such as Storable?
474		843
475	=item relay => $port, @msg	844	In fact, any AnyEvent::MP node will happily accept Storable as framing
		845	format, but currently there is no way to make a node use Storable by
		846	default.
476		847
477	Simply forwards the message to the given port.	848	The default framing protocol is JSON because a) JSON::XS is many times
		849	faster for small messages and b) most importantly, after years of
		850	experience we found that object serialisation is causing more problems
		851	than it gains: Just like function calls, objects simply do not travel
		852	easily over the network, mostly because they will always be a copy, so you
		853	always have to re-think your design.
478		854
479	=item eval => $string[ @reply]	855	Keeping your messages simple, concentrating on data structures rather than
480		856	objects, will keep your messages clean, tidy and efficient.
481	Evaluates the given string. If C<@reply> is given, then a message of the
482	form C<@reply, $@, @evalres> is sent.
483
484	Example: crash another node.
485
486	snd $othernode, eval => "exit";
487
488	=item time => @reply
489
490	Replies the the current node time to C<@reply>.
491
492	Example: tell the current node to send the current time to C<$myport> in a
493	C<timereply> message.
494
495	snd $NODE, time => $myport, timereply => 1, 2;
496	# => snd $myport, timereply => 1, 2, <time>
497		857
498	=back	858	=back
499		859
500	=head1 SEE ALSO	860	=head1 SEE ALSO
501		861

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Revision 1.62 by root, Thu Aug 27 07:12:48 2009 UTC