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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.27 by root, Tue Aug 4 22:13:45 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		46	AnyEvent::MP::Intro - outdated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
…		…
35	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
36	manual page.	60	manual page.
37		61
38	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
39	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 -
40	stay tuned! The basic API should be finished, however.	64	stay tuned!
41		65
42	=head1 CONCEPTS	66	=head1 CONCEPTS
43		67
44	=over 4	68	=over 4
45		69
46	=item port	70	=item port
47		71
48	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).
49	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
50	messages they match, messages will not be queued.	75	some messages. Messages will not be queued.
51		76
52	=item port id - C<noderef#portname>	77	=item port id - C<noderef#portname>
53		78
54	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
55	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.
56		83
57	=item node	84	=item node
58		85
59	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,
60	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
61	among other things.	88	ports.
62		89
63	Initially, nodes are either private (single-process only) or hidden	90	Nodes are either private (single-process only), slaves (can only talk to
64	(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
65	public" can you send them messages from unrelated other nodes.	92	from any other node).
66		93
67	=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>
68		95
69	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
70	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
71	node (for public nodes).	98	node (for public nodes).
72		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
73	=back	109	=back
74		110
75	=head1 VARIABLES/FUNCTIONS	111	=head1 VARIABLES/FUNCTIONS
76		112
77	=over 4	113	=over 4
78		114
79	=cut	115	=cut
80		116
81	package AnyEvent::MP;	117	package AnyEvent::MP;
82		118
83	use AnyEvent::MP::Base;	119	use AnyEvent::MP::Kernel;
84		120
85	use common::sense;	121	use common::sense;
86		122
87	use Carp ();	123	use Carp ();
88		124
89	use AE ();	125	use AE ();
90		126
91	use base "Exporter";	127	use base "Exporter";
92		128
93	our $VERSION = '0.1';	129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		130
94	our @EXPORT = qw(	131	our @EXPORT = qw(
95	NODE $NODE *SELF node_of _any_	132	NODE $NODE *SELF node_of after
96	become_slave become_public	133	resolve_node initialise_node
97	snd rcv mon kil reg psub	134	snd rcv mon mon_guard kil reg psub spawn
98	port	135	port
99	);	136	);
100		137
101	our $SELF;	138	our $SELF;
102		139
…		…
106	kil $SELF, die => $msg;	143	kil $SELF, die => $msg;
107	}	144	}
108		145
109	=item $thisnode = NODE / $NODE	146	=item $thisnode = NODE / $NODE
110		147
111	The C<NODE> function returns, and the C<$NODE> variable contains	148	The C<NODE> function returns, and the C<$NODE> variable contains the
112	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
113	to C<become_public> or C<become_slave>, after which all local port	150	C<initialise_node>.
114	identifiers become invalid.
115		151
116	=item $noderef = node_of $portid	152	=item $noderef = node_of $port
117		153
118	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
119		261
120	=item $SELF	262	=item $SELF
121		263
122	Contains the current port id while executing C<rcv> callbacks or C<psub>	264	Contains the current port id while executing C<rcv> callbacks or C<psub>
123	blocks.	265	blocks.
…		…
126		268
127	Due to some quirks in how perl exports variables, it is impossible to	269	Due to some quirks in how perl exports variables, it is impossible to
128	just export C<$SELF>, all the symbols called C<SELF> are exported by this	270	just export C<$SELF>, all the symbols called C<SELF> are exported by this
129	module, but only C<$SELF> is currently used.	271	module, but only C<$SELF> is currently used.
130		272
131	=item snd $portid, type => @data	273	=item snd $port, type => @data
132		274
133	=item snd $portid, @msg	275	=item snd $port, @msg
134		276
135	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
136	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.
137	stringifies a sa port ID (such as a port object :).
138		279
139	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
140	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
141	type etc.).	282	type etc.).
142		283
143	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
144	function: modifying any argument is not allowed and can cause many	285	function: modifying any argument is not allowed and can cause many
145	problems.	286	problems.
…		…
148	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
149	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
150	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
151	node, anything can be passed.	292	node, anything can be passed.
152		293
153	=item kil $portid[, @reason]	294	=item $local_port = port
154		295
155	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.
156		298
157	If no C<@reason> is specified, then the port is killed "normally" (linked	299	=item $local_port = port { my @msg = @_ }
158	ports will not be kileld, or even notified).
159		300
160	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
161	C<mon>, see below).	302	creating a port and calling C<rcv $port, $callback> on it.
162		303
163	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
164	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.
165		308
166	Transport/communication errors are reported as C<< transport_error =>	309	If you want to stop/destroy the port, simply C<kil> it:
167	$message >>.
168		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
169	=item $guard = mon $portid, $cb->(@reason)	478	=item $guard = mon $port, $cb->(@reason)
170		479
171	=item $guard = mon $portid, $otherport	480	=item $guard = mon $port, $rcvport
172		481
		482	=item $guard = mon $port
		483
173	=item $guard = mon $portid, $otherport, @msg	484	=item $guard = mon $port, $rcvport, @msg
174		485
175	Monitor the given port and do something when the port is killed.	486	Monitor the given port and do something when the port is killed or
		487	messages to it were lost, and optionally return a guard that can be used
		488	to stop monitoring again.
176		489
		490	C<mon> effectively guarantees that, in the absence of hardware failures,
		491	that after starting the monitor, either all messages sent to the port
		492	will arrive, or the monitoring action will be invoked after possible
		493	message loss has been detected. No messages will be lost "in between"
		494	(after the first lost message no further messages will be received by the
		495	port). After the monitoring action was invoked, further messages might get
		496	delivered again.
		497
		498	Note that monitoring-actions are one-shot: once released, they are removed
		499	and will not trigger again.
		500
177	In the first form, the callback is simply called with any number	501	In the first form (callback), the callback is simply called with any
178	of C<@reason> elements (no @reason means that the port was deleted	502	number of C<@reason> elements (no @reason means that the port was deleted
179	"normally"). Note also that I<< the callback B<must> never die >>, so use	503	"normally"). Note also that I<< the callback B<must> never die >>, so use
180	C<eval> if unsure.	504	C<eval> if unsure.
181		505
182	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	506	In the second form (another port given), the other port (C<$rcvport>)
183	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
184	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.
185		510
		511	The third form (kill self) is the same as the second form, except that
		512	C<$rvport> defaults to C<$SELF>.
		513
186	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.
187		523
188	Example: call a given callback when C<$port> is killed.	524	Example: call a given callback when C<$port> is killed.
189		525
190	mon $port, sub { warn "port died because of <@_>\n" };	526	mon $port, sub { warn "port died because of <@_>\n" };
191		527
192	Example: kill ourselves when C<$port> is killed abnormally.	528	Example: kill ourselves when C<$port> is killed abnormally.
193		529
194	mon $port, $self;	530	mon $port;
195		531
196	Example: send us a restart message another C<$port> is killed.	532	Example: send us a restart message when another C<$port> is killed.
197		533
198	mon $port, $self => "restart";	534	mon $port, $self => "restart";
199		535
200	=cut	536	=cut
201		537
202	sub mon {	538	sub mon {
203	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	539	my ($noderef, $port) = split /#/, shift, 2;
204		540
205	my $node = $NODE{$noderef} \|\| add_node $noderef;	541	my $node = $NODE{$noderef} \|\| add_node $noderef;
206		542
207	#TODO: ports must not be references	543	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
208	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {	544
		545	unless (ref $cb) {
209	if (@_) {	546	if (@_) {
210	# send a kill info message	547	# send a kill info message
211	my (@msg) = ($cb, @_);	548	my (@msg) = ($cb, @_);
212	$cb = sub { snd @msg, @_ };	549	$cb = sub { snd @msg, @_ };
213	} else {	550	} else {
…		…
242	=cut	579	=cut
243		580
244	sub mon_guard {	581	sub mon_guard {
245	my ($port, @refs) = @_;	582	my ($port, @refs) = @_;
246		583
		584	#TODO: mon-less form?
		585
247	mon $port, sub { 0 && @refs }	586	mon $port, sub { 0 && @refs }
248	}	587	}
249		588
250	=item lnk $port1, $port2	589	=item kil $port[, @reason]
251		590
252	Link two ports. This is simply a shorthand for:	591	Kill the specified port with the given C<@reason>.
253		592
254	mon $port1, $port2;	593	If no C<@reason> is specified, then the port is killed "normally" (linked
255	mon $port2, $port1;	594	ports will not be kileld, or even notified).
256		595
257	It means that if either one is killed abnormally, the other one gets	596	Otherwise, linked ports get killed with the same reason (second form of
258	killed as well.	597	C<mon>, see below).
259		598
260	=item $local_port = port	599	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		600	will be reported as reason C<< die => $@ >>.
261		601
262	Create a new local port object that supports message matching.	602	Transport/communication errors are reported as C<< transport_error =>
		603	$message >>.
263		604
264	=item $portid = port { my @msg = @_; $finished }
265
266	Creates a "mini port", that is, a very lightweight port without any
267	pattern matching behind it, and returns its ID.
268
269	The block will be called for every message received on the port. When the
270	callback returns a true value its job is considered "done" and the port
271	will be destroyed. Otherwise it will stay alive.
272
273	The message will be passed as-is, no extra argument (i.e. no port id) will
274	be passed to the callback.
275
276	If you need the local port id in the callback, this works nicely:
277
278	my $port; $port = miniport {
279	snd $otherport, reply => $port;
280	};
281
282	=cut	605	=cut
283		606
284	sub port(;&) {	607	=item $port = spawn $node, $initfunc[, @initdata]
285	my $id = "$UNIQ." . $ID++;
286	my $port = "$NODE#$id";
287		608
288	if (@_) {	609	Creates a port on the node C<$node> (which can also be a port ID, in which
289	my $cb = shift;	610	case it's the node where that port resides).
290	$PORT{$id} = sub {	611
291	local $SELF = $port;	612	The port ID of the newly created port is return immediately, and it is
292	eval {	613	permissible to immediately start sending messages or monitor the port.
293	&$cb	614
294	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 {
295	};	645	...
296	_self_die if $@;
297	};
298	} else {
299	my $self = bless {
300	id => "$NODE#$id",
301	}, "AnyEvent::MP::Port";
302
303	$PORT_DATA{$id} = $self;
304	$PORT{$id} = sub {
305	local $SELF = $port;
306
307	eval {
308	for (@{ $self->{rc0}{$_[0]} }) {
309	$_ && &{$_->[0]}
310	&& undef $_;
311	}
312
313	for (@{ $self->{rcv}{$_[0]} }) {
314	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
315	&& &{$_->[0]}
316	&& undef $_;
317	}
318
319	for (@{ $self->{any} }) {
320	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
321	&& &{$_->[0]}
322	&& undef $_;
323	}
324	};
325	_self_die if $@;
326	};	646	};
327	}	647	}
328		648
329	$port
330	}
331
332	=item reg $portid, $name
333
334	Registers the given port under the name C<$name>. If the name already
335	exists it is replaced.
336
337	A port can only be registered under one well known name.
338
339	A port automatically becomes unregistered when it is killed.
340
341	=cut	649	=cut
342		650
343	sub reg(@) {	651	sub _spawn {
344	my ($portid, $name) = @_;	652	my $port = shift;
		653	my $init = shift;
345		654
346	$REG{$name} = $portid;	655	local $SELF = "$NODE#$port";
347	}	656	eval {
348		657	&{ load_func $init }
349	=item rcv $portid, tagstring => $callback->(@msg), ...
350
351	=item rcv $portid, $smartmatch => $callback->(@msg), ...
352
353	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
354
355	Register callbacks to be called on matching messages on the given port.
356
357	The callback has to return a true value when its work is done, after
358	which is will be removed, or a false value in which case it will stay
359	registered.
360
361	The global C<$SELF> (exported by this module) contains C<$portid> while
362	executing the callback.
363
364	Runtime errors wdurign callback execution will result in the port being
365	C<kil>ed.
366
367	If the match is an array reference, then it will be matched against the
368	first elements of the message, otherwise only the first element is being
369	matched.
370
371	Any element in the match that is specified as C<_any_> (a function
372	exported by this module) matches any single element of the message.
373
374	While not required, it is highly recommended that the first matching
375	element is a string identifying the message. The one-string-only match is
376	also the most efficient match (by far).
377
378	=cut
379
380	sub rcv($@) {
381	my ($noderef, $port) = split /#/, shift, 2;
382
383	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
384	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
385
386	my $self = $PORT_DATA{$port}
387	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
388
389	"AnyEvent::MP::Port" eq ref $self
390	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
391
392	while (@_) {
393	my ($match, $cb) = splice @_, 0, 2;
394
395	if (!ref $match) {
396	push @{ $self->{rc0}{$match} }, [$cb];
397	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
398	my ($type, @match) = @$match;
399	@match
400	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
401	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
402	} else {
403	push @{ $self->{any} }, [$cb, $match];
404	}
405	}
406	}
407
408	=item $closure = psub { BLOCK }
409
410	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
411	closure is executed, sets up the environment in the same way as in C<rcv>
412	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
413
414	This is useful when you register callbacks from C<rcv> callbacks:
415
416	rcv delayed_reply => sub {
417	my ($delay, @reply) = @_;
418	my $timer = AE::timer $delay, 0, psub {
419	snd @reply, $SELF;
420	};
421	};	658	};
422
423	=cut
424
425	sub psub(&) {
426	my $cb = shift;
427
428	my $port = $SELF
429	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
430
431	sub {
432	local $SELF = $port;
433
434	if (wantarray) {
435	my @res = eval { &$cb };
436	_self_die if $@;	659	_self_die if $@;
437	@res	660	}
438	} else {	661
439	my $res = eval { &$cb };	662	sub spawn(@) {
440	_self_die if $@;	663	my ($noderef, undef) = split /#/, shift, 2;
441	$res	664
442	}	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	? $action[0]()
		693	: snd @action;
443	}	694	};
444	}	695	}
445		696
446	=back	697	=back
447		698
448	=head1 FUNCTIONS FOR NODES
449
450	=over 4
451
452	=item become_public endpoint...
453
454	Tells the node to become a public node, i.e. reachable from other nodes.
455
456	If no arguments are given, or the first argument is C<undef>, then
457	AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the
458	local nodename resolves to.
459
460	Otherwise the first argument must be an array-reference with transport
461	endpoints ("ip:port", "hostname:port") or port numbers (in which case the
462	local nodename is used as hostname). The endpoints are all resolved and
463	will become the node reference.
464
465	=cut
466
467	=back
468
469	=head1 NODE MESSAGES
470
471	Nodes understand the following messages sent to them. Many of them take
472	arguments called C<@reply>, which will simply be used to compose a reply
473	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
474	the remaining arguments are simply the message data.
475
476	=over 4
477
478	=cut
479
480	=item lookup => $name, @reply
481
482	Replies with the port ID of the specified well-known port, or C<undef>.
483
484	=item devnull => ...
485
486	Generic data sink/CPU heat conversion.
487
488	=item relay => $port, @msg
489
490	Simply forwards the message to the given port.
491
492	=item eval => $string[ @reply]
493
494	Evaluates the given string. If C<@reply> is given, then a message of the
495	form C<@reply, $@, @evalres> is sent.
496
497	Example: crash another node.
498
499	snd $othernode, eval => "exit";
500
501	=item time => @reply
502
503	Replies the the current node time to C<@reply>.
504
505	Example: tell the current node to send the current time to C<$myport> in a
506	C<timereply> message.
507
508	snd $NODE, time => $myport, timereply => 1, 2;
509	# => snd $myport, timereply => 1, 2, <time>
510
511	=back
512
513	=head1 AnyEvent::MP vs. Distributed Erlang	699	=head1 AnyEvent::MP vs. Distributed Erlang
514		700
515	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	701	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
516	== aemp node, erlang process == aemp port), so many of the documents and	702	== aemp node, Erlang process == aemp port), so many of the documents and
517	programming techniques employed by erlang apply to AnyEvent::MP. Here is a	703	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
518	sample:	704	sample:
519		705
520	http://www.erlang.se/doc/programming_rules.shtml	706	http://www.Erlang.se/doc/programming_rules.shtml
521	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	707	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
522	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6	708	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
523	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	709	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
524		710
525	Despite the similarities, there are also some important differences:	711	Despite the similarities, there are also some important differences:
526		712
527	=over 4	713	=over 4
528		714
…		…
533	convenience functionality.	719	convenience functionality.
534		720
535	This means that AEMP requires a less tightly controlled environment at the	721	This means that AEMP requires a less tightly controlled environment at the
536	cost of longer node references and a slightly higher management overhead.	722	cost of longer node references and a slightly higher management overhead.
537		723
		724	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		725	uses "local ports are like remote ports".
		726
		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
538	=item * Erlang uses processes and a mailbox, AEMP does not queue.	739	=item * Erlang uses processes and a mailbox, AEMP does not queue.
539		740
540	Erlang uses processes that selctively receive messages, and therefore	741	Erlang uses processes that selectively receive messages, and therefore
541	needs a queue. AEMP is event based, queuing messages would serve no useful	742	needs a queue. AEMP is event based, queuing messages would serve no
542	purpose.	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.
543		746
544	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	747	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
545		748
546	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	749	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
547		750
548	Sending messages in erlang is synchronous and blocks the process. AEMP	751	Sending messages in Erlang is synchronous and blocks the process (and
549	sends are immediate, connection establishment is handled in the	752	so does not need a queue that can overflow). AEMP sends are immediate,
550	background.	753	connection establishment is handled in the background.
551		754
552	=item * Erlang can silently lose messages, AEMP cannot.	755	=item * Erlang suffers from silent message loss, AEMP does not.
553		756
554	Erlang makes few guarantees on messages delivery - messages can get lost	757	Erlang makes few guarantees on messages delivery - messages can get lost
555	without any of the processes realising it (i.e. you send messages a, b,	758	without any of the processes realising it (i.e. you send messages a, b,
556	and c, and the other side only receives messages a and c).	759	and c, and the other side only receives messages a and c).
557		760
558	AEMP guarantees correct ordering, and the guarantee that there are no	761	AEMP guarantees correct ordering, and the guarantee that there are no
559	holes in the message sequence.	762	holes in the message sequence.
560		763
561	=item * In erlang, processes can be declared dead and later be found to be	764	=item * In Erlang, processes can be declared dead and later be found to be
562	alive.	765	alive.
563		766
564	In erlang it can happen that a monitored process is declared dead and	767	In Erlang it can happen that a monitored process is declared dead and
565	linked processes get killed, but later it turns out that the process is	768	linked processes get killed, but later it turns out that the process is
566	still alive - and can receive messages.	769	still alive - and can receive messages.
567		770
568	In AEMP, when port monitoring detects a port as dead, then that port will	771	In AEMP, when port monitoring detects a port as dead, then that port will
569	eventually be killed - it cannot happen that a node detects a port as dead	772	eventually be killed - it cannot happen that a node detects a port as dead
570	and then later sends messages to it, finding it is still alive.	773	and then later sends messages to it, finding it is still alive.
571		774
572	=item * Erlang can send messages to the wrong port, AEMP does not.	775	=item * Erlang can send messages to the wrong port, AEMP does not.
573		776
574	In erlang it is quite possible that a node that restarts reuses a process	777	In Erlang it is quite likely that a node that restarts reuses a process ID
575	ID known to other nodes for a completely different process, causing	778	known to other nodes for a completely different process, causing messages
576	messages destined for that process to end up in an unrelated process.	779	destined for that process to end up in an unrelated process.
577		780
578	AEMP never reuses port IDs, so old messages or old port IDs floating	781	AEMP never reuses port IDs, so old messages or old port IDs floating
579	around in the network will not be sent to an unrelated port.	782	around in the network will not be sent to an unrelated port.
580		783
581	=item * Erlang uses unprotected connections, AEMP uses secure	784	=item * Erlang uses unprotected connections, AEMP uses secure
582	authentication and can use TLS.	785	authentication and can use TLS.
583		786
584	AEMP can use a proven protocol - SSL/TLS - to protect connections and	787	AEMP can use a proven protocol - SSL/TLS - to protect connections and
585	securely authenticate nodes.	788	securely authenticate nodes.
586		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).
		822
		823	=back
		824
		825	=head1 RATIONALE
		826
		827	=over 4
		828
		829	=item Why strings for ports and noderefs, why not objects?
		830
		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.
		835
		836	Strings can easily be printed, easily serialised etc. and need no special
		837	procedures to be "valid".
		838
		839	And a a miniport consists of a single closure stored in a global hash - it
		840	can't become much cheaper.
		841
		842	=item Why favour JSON, why not real serialising format such as Storable?
		843
		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.
		847
		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.
		854
		855	Keeping your messages simple, concentrating on data structures rather than
		856	objects, will keep your messages clean, tidy and efficient.
		857
587	=back	858	=back
588		859
589	=head1 SEE ALSO	860	=head1 SEE ALSO
590		861
591	L<AnyEvent>.	862	L<AnyEvent>.

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