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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.29 by root, Tue Aug 4 23:16:57 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		46	AnyEvent::MP::Intro - outdated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).	72	A port is something you can send messages to (with the C<snd> function).
49		73
50	Some ports allow you to register C<rcv> handlers that can match specific	74	Ports allow you to register C<rcv> handlers that can match all or just
51	messages. All C<rcv> handlers will receive messages they match, messages	75	some messages. Messages will not be queued.
52	will not be queued.
53		76
54	=item port id - C<noderef#portname>	77	=item port id - C<noderef#portname>
55		78
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	79	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
57	separator, and a port name (a printable string of unspecified format). An	80	separator, and a port name (a printable string of unspecified format). An
58	exception is the the node port, whose ID is identical to it's node	81	exception is the the node port, whose ID is identical to its node
59	reference.	82	reference.
60		83
61	=item node	84	=item node
62		85
63	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,
64	port. You can send messages to node ports to find existing ports or to	87	which provides nodes to manage each other remotely, and to create new
65	create new ports, among other things.	88	ports.
66		89
67	Nodes are either private (single-process only), slaves (connected to a	90	Nodes are either private (single-process only), slaves (can only talk to
68	master node only) or public nodes (connectable from unrelated nodes).	91	public nodes, but do not need an open port) or public nodes (connectable
		92	from any other node).
69		93
70	=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>
71		95
72	A node reference is a string that either simply identifies the node (for	96	A node reference is a string that either simply identifies the node (for
73	private and slave 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
…		…
90		114
91	=cut	115	=cut
92		116
93	package AnyEvent::MP;	117	package AnyEvent::MP;
94		118
95	use AnyEvent::MP::Base;	119	use AnyEvent::MP::Kernel;
96		120
97	use common::sense;	121	use common::sense;
98		122
99	use Carp ();	123	use Carp ();
100		124
101	use AE ();	125	use AE ();
102		126
103	use base "Exporter";	127	use base "Exporter";
104		128
105	our $VERSION = '0.1';	129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		130
106	our @EXPORT = qw(	131	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	132	NODE $NODE *SELF node_of after
108	resolve_node	133	resolve_node initialise_node
109	become_slave become_public
110	snd rcv mon kil reg psub	134	snd rcv mon mon_guard kil reg psub spawn
111	port	135	port
112	);	136	);
113		137
114	our $SELF;	138	our $SELF;
115		139
…		…
119	kil $SELF, die => $msg;	143	kil $SELF, die => $msg;
120	}	144	}
121		145
122	=item $thisnode = NODE / $NODE	146	=item $thisnode = NODE / $NODE
123		147
124	The C<NODE> function returns, and the C<$NODE> variable contains	148	The C<NODE> function returns, and the C<$NODE> variable contains the
125	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
126	to C<become_public> or C<become_slave>, after which all local port	150	C<initialise_node>.
127	identifiers become invalid.
128		151
129	=item $noderef = node_of $portid	152	=item $noderef = node_of $port
130		153
131	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";
132		232
133	=item $cv = resolve_node $noderef	233	=item $cv = resolve_node $noderef
134		234
135	Takes an unresolved node reference that may contain hostnames and	235	Takes an unresolved node reference that may contain hostnames and
136	abbreviated IDs, resolves all of them and returns a resolved node	236	abbreviated IDs, resolves all of them and returns a resolved node
…		…
168		268
169	Due to some quirks in how perl exports variables, it is impossible to	269	Due to some quirks in how perl exports variables, it is impossible to
170	just export C<$SELF>, all the symbols called C<SELF> are exported by this	270	just export C<$SELF>, all the symbols called C<SELF> are exported by this
171	module, but only C<$SELF> is currently used.	271	module, but only C<$SELF> is currently used.
172		272
173	=item snd $portid, type => @data	273	=item snd $port, type => @data
174		274
175	=item snd $portid, @msg	275	=item snd $port, @msg
176		276
177	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
178	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.
179	stringifies a sa port ID (such as a port object :).
180		279
181	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
182	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
183	type etc.).	282	type etc.).
184		283
185	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
186	function: modifying any argument is not allowed and can cause many	285	function: modifying any argument is not allowed and can cause many
187	problems.	286	problems.
…		…
190	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
191	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
192	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
193	node, anything can be passed.	292	node, anything can be passed.
194		293
195	=item kil $portid[, @reason]	294	=item $local_port = port
196		295
197	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.
198		298
199	If no C<@reason> is specified, then the port is killed "normally" (linked	299	=item $local_port = port { my @msg = @_ }
200	ports will not be kileld, or even notified).
201		300
202	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
203	C<mon>, see below).	302	creating a port and calling C<rcv $port, $callback> on it.
204		303
205	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
206	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.
207		308
208	Transport/communication errors are reported as C<< transport_error =>	309	If you want to stop/destroy the port, simply C<kil> it:
209	$message >>.
210		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
211	=item $guard = mon $portid, $cb->(@reason)	478	=item $guard = mon $port, $cb->(@reason)
212		479
213	=item $guard = mon $portid, $otherport	480	=item $guard = mon $port, $rcvport
214		481
		482	=item $guard = mon $port
		483
215	=item $guard = mon $portid, $otherport, @msg	484	=item $guard = mon $port, $rcvport, @msg
216		485
217	Monitor the given port and do something when the port is killed.	486	Monitor the given port and do something when the port is killed or
		487	messages to it were lost, and optionally return a guard that can be used
		488	to stop monitoring again.
218		489
		490	C<mon> effectively guarantees that, in the absence of hardware failures,
		491	that after starting the monitor, either all messages sent to the port
		492	will arrive, or the monitoring action will be invoked after possible
		493	message loss has been detected. No messages will be lost "in between"
		494	(after the first lost message no further messages will be received by the
		495	port). After the monitoring action was invoked, further messages might get
		496	delivered again.
		497
		498	Note that monitoring-actions are one-shot: once released, they are removed
		499	and will not trigger again.
		500
219	In the first form, the callback is simply called with any number	501	In the first form (callback), the callback is simply called with any
220	of C<@reason> elements (no @reason means that the port was deleted	502	number of C<@reason> elements (no @reason means that the port was deleted
221	"normally"). Note also that I<< the callback B<must> never die >>, so use	503	"normally"). Note also that I<< the callback B<must> never die >>, so use
222	C<eval> if unsure.	504	C<eval> if unsure.
223		505
224	In the second form, the other port will be C<kil>'ed with C<@reason>, iff	506	In the second form (another port given), the other port (C<$rcvport>)
225	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
226	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.
227		510
		511	The third form (kill self) is the same as the second form, except that
		512	C<$rvport> defaults to C<$SELF>.
		513
228	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.
229		523
230	Example: call a given callback when C<$port> is killed.	524	Example: call a given callback when C<$port> is killed.
231		525
232	mon $port, sub { warn "port died because of <@_>\n" };	526	mon $port, sub { warn "port died because of <@_>\n" };
233		527
234	Example: kill ourselves when C<$port> is killed abnormally.	528	Example: kill ourselves when C<$port> is killed abnormally.
235		529
236	mon $port, $self;	530	mon $port;
237		531
238	Example: send us a restart message another C<$port> is killed.	532	Example: send us a restart message when another C<$port> is killed.
239		533
240	mon $port, $self => "restart";	534	mon $port, $self => "restart";
241		535
242	=cut	536	=cut
243		537
244	sub mon {	538	sub mon {
245	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);	539	my ($noderef, $port) = split /#/, shift, 2;
246		540
247	my $node = $NODE{$noderef} \|\| add_node $noderef;	541	my $node = $NODE{$noderef} \|\| add_node $noderef;
248		542
249	#TODO: ports must not be references	543	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
250	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {	544
		545	unless (ref $cb) {
251	if (@_) {	546	if (@_) {
252	# send a kill info message	547	# send a kill info message
253	my (@msg) = ($cb, @_);	548	my (@msg) = ($cb, @_);
254	$cb = sub { snd @msg, @_ };	549	$cb = sub { snd @msg, @_ };
255	} else {	550	} else {
…		…
284	=cut	579	=cut
285		580
286	sub mon_guard {	581	sub mon_guard {
287	my ($port, @refs) = @_;	582	my ($port, @refs) = @_;
288		583
		584	#TODO: mon-less form?
		585
289	mon $port, sub { 0 && @refs }	586	mon $port, sub { 0 && @refs }
290	}	587	}
291		588
292	=item lnk $port1, $port2	589	=item kil $port[, @reason]
293		590
294	Link two ports. This is simply a shorthand for:	591	Kill the specified port with the given C<@reason>.
295		592
296	mon $port1, $port2;	593	If no C<@reason> is specified, then the port is killed "normally" (linked
297	mon $port2, $port1;	594	ports will not be kileld, or even notified).
298		595
299	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
300	killed as well.	597	C<mon>, see below).
301		598
302	=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 => $@ >>.
303		601
304	Create a new local port object that supports message matching.	602	Transport/communication errors are reported as C<< transport_error =>
		603	$message >>.
305		604
306	=item $portid = port { my @msg = @_; $finished }
307
308	Creates a "mini port", that is, a very lightweight port without any
309	pattern matching behind it, and returns its ID.
310
311	The block will be called for every message received on the port. When the
312	callback returns a true value its job is considered "done" and the port
313	will be destroyed. Otherwise it will stay alive.
314
315	The message will be passed as-is, no extra argument (i.e. no port id) will
316	be passed to the callback.
317
318	If you need the local port id in the callback, this works nicely:
319
320	my $port; $port = miniport {
321	snd $otherport, reply => $port;
322	};
323
324	=cut	605	=cut
325		606
326	sub port(;&) {	607	=item $port = spawn $node, $initfunc[, @initdata]
327	my $id = "$UNIQ." . $ID++;
328	my $port = "$NODE#$id";
329		608
330	if (@_) {	609	Creates a port on the node C<$node> (which can also be a port ID, in which
331	my $cb = shift;	610	case it's the node where that port resides).
332	$PORT{$id} = sub {	611
333	local $SELF = $port;	612	The port ID of the newly created port is return immediately, and it is
334	eval {	613	permissible to immediately start sending messages or monitor the port.
335	&$cb	614
336	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 {
337	};	645	...
338	_self_die if $@;
339	};
340	} else {
341	my $self = bless {
342	id => "$NODE#$id",
343	}, "AnyEvent::MP::Port";
344
345	$PORT_DATA{$id} = $self;
346	$PORT{$id} = sub {
347	local $SELF = $port;
348
349	eval {
350	for (@{ $self->{rc0}{$_[0]} }) {
351	$_ && &{$_->[0]}
352	&& undef $_;
353	}
354
355	for (@{ $self->{rcv}{$_[0]} }) {
356	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
357	&& &{$_->[0]}
358	&& undef $_;
359	}
360
361	for (@{ $self->{any} }) {
362	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
363	&& &{$_->[0]}
364	&& undef $_;
365	}
366	};
367	_self_die if $@;
368	};	646	};
369	}	647	}
370		648
371	$port
372	}
373
374	=item reg $portid, $name
375
376	Registers the given port under the name C<$name>. If the name already
377	exists it is replaced.
378
379	A port can only be registered under one well known name.
380
381	A port automatically becomes unregistered when it is killed.
382
383	=cut	649	=cut
384		650
385	sub reg(@) {	651	sub _spawn {
386	my ($portid, $name) = @_;	652	my $port = shift;
		653	my $init = shift;
387		654
388	$REG{$name} = $portid;	655	local $SELF = "$NODE#$port";
389	}	656	eval {
390		657	&{ load_func $init }
391	=item rcv $portid, tagstring => $callback->(@msg), ...
392
393	=item rcv $portid, $smartmatch => $callback->(@msg), ...
394
395	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
396
397	Register callbacks to be called on matching messages on the given port.
398
399	The callback has to return a true value when its work is done, after
400	which is will be removed, or a false value in which case it will stay
401	registered.
402
403	The global C<$SELF> (exported by this module) contains C<$portid> while
404	executing the callback.
405
406	Runtime errors wdurign callback execution will result in the port being
407	C<kil>ed.
408
409	If the match is an array reference, then it will be matched against the
410	first elements of the message, otherwise only the first element is being
411	matched.
412
413	Any element in the match that is specified as C<_any_> (a function
414	exported by this module) matches any single element of the message.
415
416	While not required, it is highly recommended that the first matching
417	element is a string identifying the message. The one-string-only match is
418	also the most efficient match (by far).
419
420	=cut
421
422	sub rcv($@) {
423	my ($noderef, $port) = split /#/, shift, 2;
424
425	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
426	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
427
428	my $self = $PORT_DATA{$port}
429	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
430
431	"AnyEvent::MP::Port" eq ref $self
432	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
433
434	while (@_) {
435	my ($match, $cb) = splice @_, 0, 2;
436
437	if (!ref $match) {
438	push @{ $self->{rc0}{$match} }, [$cb];
439	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
440	my ($type, @match) = @$match;
441	@match
442	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
443	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
444	} else {
445	push @{ $self->{any} }, [$cb, $match];
446	}
447	}
448	}
449
450	=item $closure = psub { BLOCK }
451
452	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
453	closure is executed, sets up the environment in the same way as in C<rcv>
454	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
455
456	This is useful when you register callbacks from C<rcv> callbacks:
457
458	rcv delayed_reply => sub {
459	my ($delay, @reply) = @_;
460	my $timer = AE::timer $delay, 0, psub {
461	snd @reply, $SELF;
462	};
463	};	658	};
464
465	=cut
466
467	sub psub(&) {
468	my $cb = shift;
469
470	my $port = $SELF
471	or Carp::croak "psub can only be called from within rcv or psub callbacks, not";
472
473	sub {
474	local $SELF = $port;
475
476	if (wantarray) {
477	my @res = eval { &$cb };
478	_self_die if $@;	659	_self_die if $@;
479	@res	660	}
480	} else {	661
481	my $res = eval { &$cb };	662	sub spawn(@) {
482	_self_die if $@;	663	my ($noderef, undef) = split /#/, shift, 2;
483	$res	664
484	}	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;
485	}	694	};
486	}	695	}
487		696
488	=back	697	=back
489		698
490	=head1 FUNCTIONS FOR NODES
491
492	=over 4
493
494	=item become_public $noderef
495
496	Tells the node to become a public node, i.e. reachable from other nodes.
497
498	The first argument is the (unresolved) node reference of the local node
499	(if missing then the empty string is used).
500
501	It is quite common to not specify anything, in which case the local node
502	tries to listen on the default port, or to only specify a port number, in
503	which case AnyEvent::MP tries to guess the local addresses.
504
505	=cut
506
507	=back
508
509	=head1 NODE MESSAGES
510
511	Nodes understand the following messages sent to them. Many of them take
512	arguments called C<@reply>, which will simply be used to compose a reply
513	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
514	the remaining arguments are simply the message data.
515
516	While other messages exist, they are not public and subject to change.
517
518	=over 4
519
520	=cut
521
522	=item lookup => $name, @reply
523
524	Replies with the port ID of the specified well-known port, or C<undef>.
525
526	=item devnull => ...
527
528	Generic data sink/CPU heat conversion.
529
530	=item relay => $port, @msg
531
532	Simply forwards the message to the given port.
533
534	=item eval => $string[ @reply]
535
536	Evaluates the given string. If C<@reply> is given, then a message of the
537	form C<@reply, $@, @evalres> is sent.
538
539	Example: crash another node.
540
541	snd $othernode, eval => "exit";
542
543	=item time => @reply
544
545	Replies the the current node time to C<@reply>.
546
547	Example: tell the current node to send the current time to C<$myport> in a
548	C<timereply> message.
549
550	snd $NODE, time => $myport, timereply => 1, 2;
551	# => snd $myport, timereply => 1, 2, <time>
552
553	=back
554
555	=head1 AnyEvent::MP vs. Distributed Erlang	699	=head1 AnyEvent::MP vs. Distributed Erlang
556		700
557	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
558	== 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
559	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
560	sample:	704	sample:
561		705
562	http://www.erlang.se/doc/programming_rules.shtml	706	http://www.Erlang.se/doc/programming_rules.shtml
563	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
564	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
565	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
566		710
567	Despite the similarities, there are also some important differences:	711	Despite the similarities, there are also some important differences:
568		712
569	=over 4	713	=over 4
570		714
…		…
575	convenience functionality.	719	convenience functionality.
576		720
577	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
578	cost of longer node references and a slightly higher management overhead.	722	cost of longer node references and a slightly higher management overhead.
579		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
580	=item * Erlang uses processes and a mailbox, AEMP does not queue.	739	=item * Erlang uses processes and a mailbox, AEMP does not queue.
581		740
582	Erlang uses processes that selctively receive messages, and therefore	741	Erlang uses processes that selectively receive messages, and therefore
583	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
584	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.
585		746
586	(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).
587		748
588	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	749	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
589		750
590	Sending messages in erlang is synchronous and blocks the process. AEMP	751	Sending messages in Erlang is synchronous and blocks the process (and
591	sends are immediate, connection establishment is handled in the	752	so does not need a queue that can overflow). AEMP sends are immediate,
592	background.	753	connection establishment is handled in the background.
593		754
594	=item * Erlang can silently lose messages, AEMP cannot.	755	=item * Erlang suffers from silent message loss, AEMP does not.
595		756
596	Erlang makes few guarantees on messages delivery - messages can get lost	757	Erlang makes few guarantees on messages delivery - messages can get lost
597	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,
598	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).
599		760
600	AEMP guarantees correct ordering, and the guarantee that there are no	761	AEMP guarantees correct ordering, and the guarantee that there are no
601	holes in the message sequence.	762	holes in the message sequence.
602		763
603	=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
604	alive.	765	alive.
605		766
606	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
607	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
608	still alive - and can receive messages.	769	still alive - and can receive messages.
609		770
610	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
611	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
612	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.
613		774
614	=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.
615		776
616	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
617	ID known to other nodes for a completely different process, causing	778	known to other nodes for a completely different process, causing messages
618	messages destined for that process to end up in an unrelated process.	779	destined for that process to end up in an unrelated process.
619		780
620	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
621	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.
622		783
623	=item * Erlang uses unprotected connections, AEMP uses secure	784	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
627	securely authenticate nodes.	788	securely authenticate nodes.
628		789
629	=item * The AEMP protocol is optimised for both text-based and binary	790	=item * The AEMP protocol is optimised for both text-based and binary
630	communications.	791	communications.
631		792
632	The AEMP protocol, unlike the erlang protocol, supports both	793	The AEMP protocol, unlike the Erlang protocol, supports both
633	language-independent text-only protocols (good for debugging) and binary,	794	language-independent text-only protocols (good for debugging) and binary,
634	language-specific serialisers (e.g. Storable).	795	language-specific serialisers (e.g. Storable).
635		796
636	It has also been carefully designed to be implementable in other languages	797	It has also been carefully designed to be implementable in other languages
637	with a minimum of work while gracefully degrading fucntionality to make the	798	with a minimum of work while gracefully degrading fucntionality to make the
638	protocol simple.	799	protocol simple.
639		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
640	=back	858	=back
641		859
642	=head1 SEE ALSO	860	=head1 SEE ALSO
643		861
644	L<AnyEvent>.	862	L<AnyEvent>.

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