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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.44 by root, Wed Aug 12 21:39:58 2009 UTC vs.
Revision 1.64 by root, Fri Aug 28 00:58:44 2009 UTC

…		…
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	13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node;
14		17
15	# ports are message endpoints	18	# ports are message endpoints
16		19
17	# sending messages	20	# sending messages
18	snd $port, type => data...;	21	snd $port, type => data...;
19	snd $port, @msg;	22	snd $port, @msg;
20	snd @msg_with_first_element_being_a_port;	23	snd @msg_with_first_element_being_a_port;
21		24
22	# miniports	25	# creating/using ports, the simple way
23	my $miniport = port { my @msg = @_; 0 };	26	my $simple_port = port { my @msg = @_; 0 };
24		27
25	# full ports	28	# creating/using ports, tagged message matching
26	my $port = port;	29	my $port = port;
27	rcv $port, smartmatch => $cb->(@msg);
28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	30	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
29	rcv $port, pong => sub { warn "pong received\n"; 0 };	31	rcv $port, pong => sub { warn "pong received\n"; 0 };
30		32
31	# remote ports	33	# create a port on another node
32	my $port = spawn $node, $initfunc, @initdata;	34	my $port = spawn $node, $initfunc, @initdata;
33
34	# more, smarter, matches (_any_ is exported by this module)
35	rcv $port, [child_died => $pid] => sub { ...
36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
37		35
38	# monitoring	36	# monitoring
39	mon $port, $cb->(@msg) # callback is invoked on death	37	mon $port, $cb->(@msg) # callback is invoked on death
40	mon $port, $otherport # kill otherport on abnormal death	38	mon $port, $otherport # kill otherport on abnormal death
41	mon $port, $otherport, @msg # send message on death	39	mon $port, $otherport, @msg # send message on death
42		40
		41	=head1 CURRENT STATUS
		42
		43	AnyEvent::MP - stable API, should work
		44	AnyEvent::MP::Intro - outdated
		45	AnyEvent::MP::Kernel - WIP
		46	AnyEvent::MP::Transport - mostly stable
		47
		48	stay tuned.
		49
43	=head1 DESCRIPTION	50	=head1 DESCRIPTION
44		51
45	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
46		53
47	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
…		…
50	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
51	manual page.	58	manual page.
52		59
53	At the moment, this module family is severly broken and underdocumented,	60	At the moment, this module family is severly broken and underdocumented,
54	so do not use. This was uploaded mainly to reserve the CPAN namespace -	61	so do not use. This was uploaded mainly to reserve the CPAN namespace -
55	stay tuned! The basic API should be finished, however.	62	stay tuned!
56		63
57	=head1 CONCEPTS	64	=head1 CONCEPTS
58		65
59	=over 4	66	=over 4
60		67
61	=item port	68	=item port
62		69
63	A port is something you can send messages to (with the C<snd> function).	70	A port is something you can send messages to (with the C<snd> function).
64		71
65	Some ports allow you to register C<rcv> handlers that can match specific	72	Ports allow you to register C<rcv> handlers that can match all or just
66	messages. All C<rcv> handlers will receive messages they match, messages	73	some messages. Messages send to ports will not be queued, regardless of
67	will not be queued.	74	anything was listening for them or not.
68		75
69	=item port id - C<noderef#portname>	76	=item port ID - C<noderef#portname>
70		77
71	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	78	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
72	separator, and a port name (a printable string of unspecified format). An	79	separator, and a port name (a printable string of unspecified format). An
73	exception is the the node port, whose ID is identical to its node	80	exception is the the node port, whose ID is identical to its node
74	reference.	81	reference.
75		82
76	=item node	83	=item node
77		84
78	A node is a single process containing at least one port - the node	85	A node is a single process containing at least one port - the node port,
79	port. You can send messages to node ports to find existing ports or to	86	which provides nodes to manage each other remotely, and to create new
80	create new ports, among other things.	87	ports.
81		88
82	Nodes are either private (single-process only), slaves (connected to a	89	Nodes are either private (single-process only), slaves (can only talk to
83	master node only) or public nodes (connectable from unrelated nodes).	90	public nodes, but do not need an open port) or public nodes (connectable
		91	from any other node).
84		92
85	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item node ID - C<[a-za-Z0-9_\-.:]+>
86		94
87	A node reference is a string that either simply identifies the node (for	95	A node ID is a string that uniquely identifies the node within a
88	private and slave nodes), or contains a recipe on how to reach a given	96	network. Depending on the configuration used, node IDs can look like a
89	node (for public nodes).	97	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		98	doesn't interpret node IDs in any way.
90		99
91	This recipe is simply a comma-separated list of C<address:port> pairs (for	100	=item binds - C<ip:port>
92	TCP/IP, other protocols might look different).
93		101
94	Node references come in two flavours: resolved (containing only numerical	102	Nodes can only talk to each other by creating some kind of connection to
95	addresses) or unresolved (where hostnames are used instead of addresses).	103	each other. To do this, nodes should listen on one or more local transport
		104	endpoints - binds. Currently, only standard C<ip:port> specifications can
		105	be used, which specify TCP ports to listen on.
96		106
97	Before using an unresolved node reference in a message you first have to	107	=item seeds - C<host:port>
98	resolve it.	108
		109	When a node starts, it knows nothing about the network. To teach the node
		110	about the network it first has to contact some other node within the
		111	network. This node is called a seed.
		112
		113	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes
		114	are expected to be long-running, and at least one of those should always
		115	be available. When nodes run out of connections (e.g. due to a network
		116	error), they try to re-establish connections to some seednodes again to
		117	join the network.
99		118
100	=back	119	=back
101		120
102	=head1 VARIABLES/FUNCTIONS	121	=head1 VARIABLES/FUNCTIONS
103		122
…		…
118	use base "Exporter";	137	use base "Exporter";
119		138
120	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	139	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
121		140
122	our @EXPORT = qw(	141	our @EXPORT = qw(
123	NODE $NODE *SELF node_of _any_	142	NODE $NODE *SELF node_of after
124	resolve_node initialise_node	143	resolve_node initialise_node
125	snd rcv mon kil reg psub spawn	144	snd rcv mon mon_guard kil reg psub spawn
126	port	145	port
127	);	146	);
128		147
129	our $SELF;	148	our $SELF;
130		149
…		…
134	kil $SELF, die => $msg;	153	kil $SELF, die => $msg;
135	}	154	}
136		155
137	=item $thisnode = NODE / $NODE	156	=item $thisnode = NODE / $NODE
138		157
139	The C<NODE> function returns, and the C<$NODE> variable contains	158	The C<NODE> function returns, and the C<$NODE> variable contains the node
140	the noderef of the local node. The value is initialised by a call	159	ID of the node running in the current process. This value is initialised by
141	to C<become_public> or C<become_slave>, after which all local port	160	a call to C<initialise_node>.
142	identifiers become invalid.
143		161
144	=item $noderef = node_of $port	162	=item $nodeid = node_of $port
145		163
146	Extracts and returns the noderef from a portid or a noderef.	164	Extracts and returns the node ID part from a port ID or a node ID.
147		165
148	=item initialise_node $noderef, $seednode, $seednode...	166	=item initialise_node $profile_name
149		167
150	=item initialise_node "slave/", $master, $master...
151
152	Before a node can talk to other nodes on the network it has to initialise	168	Before a node can talk to other nodes on the network (i.e. enter
153	itself - the minimum a node needs to know is it's own name, and optionally	169	"distributed mode") it has to initialise itself - the minimum a node needs
154	it should know the noderefs of some other nodes in the network.	170	to know is its own name, and optionally it should know the addresses of
		171	some other nodes in the network to discover other nodes.
155		172
156	This function initialises a node - it must be called exactly once (or	173	This function initialises a node - it must be called exactly once (or
157	never) before calling other AnyEvent::MP functions.	174	never) before calling other AnyEvent::MP functions.
158		175
159	All arguments are noderefs, which can be either resolved or unresolved.	176	The first argument is a profile name. If it is C<undef> or missing, then
		177	the current nodename will be used instead (i.e. F<uname -n>).
160		178
161	There are two types of networked nodes, public nodes and slave nodes:	179	The function then looks up the profile in the aemp configuration (see the
		180	L<aemp> commandline utility).
162		181
163	=over 4	182	If the profile specifies a node ID, then this will become the node ID of
		183	this process. If not, then the profile name will be used as node ID. The
		184	special node ID of C<anon/> will be replaced by a random node ID.
164		185
165	=item public nodes	186	The next step is to look up the binds in the profile, followed by binding
		187	aemp protocol listeners on all binds specified (it is possible and valid
		188	to have no binds, meaning that the node cannot be contacted form the
		189	outside. This means the node cannot talk to other nodes that also have no
		190	binds, but it can still talk to all "normal" nodes).
166		191
167	For public nodes, C<$noderef> must either be a (possibly unresolved)	192	If the profile does not specify a binds list, then the node ID will be
168	noderef, in which case it will be resolved, or C<undef> (or missing), in	193	treated as if it were of the form C<host:port>, which will be resolved and
169	which case the noderef will be guessed.	194	used as binds list.
170		195
171	Afterwards, the node will bind itself on all endpoints and try to connect	196	Lastly, the seeds list from the profile is passed to the
172	to all additional C<$seednodes> that are specified. Seednodes are optional	197	L<AnyEvent::MP::Global> module, which will then use it to keep
173	and can be used to quickly bootstrap the node into an existing network.	198	connectivity with at least on of those seed nodes at any point in time.
174		199
175	=item slave nodes	200	Example: become a distributed node listening on the guessed noderef, or
176		201	the one specified via C<aemp> for the current node. This should be the
177	When the C<$noderef> is the special string C<slave/>, then the node will	202	most common form of invocation for "daemon"-type nodes.
178	become a slave node. Slave nodes cannot be contacted from outside and will
179	route most of their traffic to the master node that they attach to.
180
181	At least one additional noderef is required: The node will try to connect
182	to all of them and will become a slave attached to the first node it can
183	successfully connect to.
184
185	=back
186
187	This function will block until all nodes have been resolved and, for slave
188	nodes, until it has successfully established a connection to a master
189	server.
190
191	Example: become a public node listening on the default node.
192		203
193	initialise_node;	204	initialise_node;
194		205
195	Example: become a public node, and try to contact some well-known master	206	Example: become an anonymous node. This form is often used for commandline
196	servers to become part of the network.	207	clients.
197		208
198	initialise_node undef, "master1", "master2";
199
200	Example: become a public node listening on port C<4041>.
201
202	initialise_node 4041;	209	initialise_node "anon/";
203		210
204	Example: become a public node, only visible on localhost port 4044.	211	Example: become a distributed node. If there is no profile of the given
		212	name, or no binds list was specified, resolve C<localhost:4044> and bind
		213	on the resulting addresses.
205		214
206	initialise_node "locahost:4044";	215	initialise_node "localhost:4044";
207
208	Example: become a slave node to any of the specified master servers.
209
210	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
211
212	=item $cv = resolve_node $noderef
213
214	Takes an unresolved node reference that may contain hostnames and
215	abbreviated IDs, resolves all of them and returns a resolved node
216	reference.
217
218	In addition to C<address:port> pairs allowed in resolved noderefs, the
219	following forms are supported:
220
221	=over 4
222
223	=item the empty string
224
225	An empty-string component gets resolved as if the default port (4040) was
226	specified.
227
228	=item naked port numbers (e.g. C<1234>)
229
230	These are resolved by prepending the local nodename and a colon, to be
231	further resolved.
232
233	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
234
235	These are resolved by using AnyEvent::DNS to resolve them, optionally
236	looking up SRV records for the C<aemp=4040> port, if no port was
237	specified.
238
239	=back
240		216
241	=item $SELF	217	=item $SELF
242		218
243	Contains the current port id while executing C<rcv> callbacks or C<psub>	219	Contains the current port id while executing C<rcv> callbacks or C<psub>
244	blocks.	220	blocks.
…		…
252	=item snd $port, type => @data	228	=item snd $port, type => @data
253		229
254	=item snd $port, @msg	230	=item snd $port, @msg
255		231
256	Send the given message to the given port ID, which can identify either	232	Send the given message to the given port ID, which can identify either
257	a local or a remote port, and can be either a string or soemthignt hat	233	a local or a remote port, and must be a port ID.
258	stringifies a sa port ID (such as a port object :).
259		234
260	While the message can be about anything, it is highly recommended to use a	235	While the message can be about anything, it is highly recommended to use a
261	string as first element (a portid, or some word that indicates a request	236	string as first element (a port ID, or some word that indicates a request
262	type etc.).	237	type etc.).
263		238
264	The message data effectively becomes read-only after a call to this	239	The message data effectively becomes read-only after a call to this
265	function: modifying any argument is not allowed and can cause many	240	function: modifying any argument is not allowed and can cause many
266	problems.	241	problems.
…		…
271	that Storable can serialise and deserialise is allowed, and for the local	246	that Storable can serialise and deserialise is allowed, and for the local
272	node, anything can be passed.	247	node, anything can be passed.
273		248
274	=item $local_port = port	249	=item $local_port = port
275		250
276	Create a new local port object that can be used either as a pattern	251	Create a new local port object and returns its port ID. Initially it has
277	matching port ("full port") or a single-callback port ("miniport"),	252	no callbacks set and will throw an error when it receives messages.
278	depending on how C<rcv> callbacks are bound to the object.
279		253
280	=item $port = port { my @msg = @_; $finished }	254	=item $local_port = port { my @msg = @_ }
281		255
282	Creates a "miniport", that is, a very lightweight port without any pattern	256	Creates a new local port, and returns its ID. Semantically the same as
283	matching behind it, and returns its ID. Semantically the same as creating
284	a port and calling C<rcv $port, $callback> on it.	257	creating a port and calling C<rcv $port, $callback> on it.
285		258
286	The block will be called for every message received on the port. When the	259	The block will be called for every message received on the port, with the
287	callback returns a true value its job is considered "done" and the port	260	global variable C<$SELF> set to the port ID. Runtime errors will cause the
288	will be destroyed. Otherwise it will stay alive.	261	port to be C<kil>ed. The message will be passed as-is, no extra argument
		262	(i.e. no port ID) will be passed to the callback.
289		263
290	The message will be passed as-is, no extra argument (i.e. no port id) will	264	If you want to stop/destroy the port, simply C<kil> it:
291	be passed to the callback.
292		265
293	If you need the local port id in the callback, this works nicely:	266	my $port = port {
294		267	my @msg = @_;
295	my $port; $port = port {	268	...
296	snd $otherport, reply => $port;	269	kil $SELF;
297	};	270	};
298		271
299	=cut	272	=cut
300		273
301	sub rcv($@);	274	sub rcv($@);
		275
		276	sub _kilme {
		277	die "received message on port without callback";
		278	}
302		279
303	sub port(;&) {	280	sub port(;&) {
304	my $id = "$UNIQ." . $ID++;	281	my $id = "$UNIQ." . $ID++;
305	my $port = "$NODE#$id";	282	my $port = "$NODE#$id";
306		283
307	if (@_) {	284	rcv $port, shift \|\| \&_kilme;
308	rcv $port, shift;
309	} else {
310	$PORT{$id} = sub { }; # nop
311	}
312		285
313	$port	286	$port
314	}	287	}
315		288
316	=item reg $port, $name
317
318	=item reg $name
319
320	Registers the given port (or C<$SELF><<< if missing) under the name
321	C<$name>. If the name already exists it is replaced.
322
323	A port can only be registered under one well known name.
324
325	A port automatically becomes unregistered when it is killed.
326
327	=cut
328
329	sub reg(@) {
330	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
331
332	$REG{$_[0]} = $port;
333	}
334
335	=item rcv $port, $callback->(@msg)	289	=item rcv $local_port, $callback->(@msg)
336		290
337	Replaces the callback on the specified miniport (after converting it to	291	Replaces the default callback on the specified port. There is no way to
338	one if required).	292	remove the default callback: use C<sub { }> to disable it, or better
339		293	C<kil> the port when it is no longer needed.
340	=item rcv $port, tagstring => $callback->(@msg), ...
341
342	=item rcv $port, $smartmatch => $callback->(@msg), ...
343
344	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
345
346	Register callbacks to be called on matching messages on the given full
347	port (after converting it to one if required) and return the port.
348
349	The callback has to return a true value when its work is done, after
350	which is will be removed, or a false value in which case it will stay
351	registered.
352		294
353	The global C<$SELF> (exported by this module) contains C<$port> while	295	The global C<$SELF> (exported by this module) contains C<$port> while
354	executing the callback.	296	executing the callback. Runtime errors during callback execution will
		297	result in the port being C<kil>ed.
355		298
356	Runtime errors during callback execution will result in the port being	299	The default callback received all messages not matched by a more specific
357	C<kil>ed.	300	C<tag> match.
358		301
359	If the match is an array reference, then it will be matched against the	302	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
360	first elements of the message, otherwise only the first element is being
361	matched.
362		303
363	Any element in the match that is specified as C<_any_> (a function	304	Register (or replace) callbacks to be called on messages starting with the
364	exported by this module) matches any single element of the message.	305	given tag on the given port (and return the port), or unregister it (when
		306	C<$callback> is C<$undef> or missing). There can only be one callback
		307	registered for each tag.
365		308
366	While not required, it is highly recommended that the first matching	309	The original message will be passed to the callback, after the first
367	element is a string identifying the message. The one-string-only match is	310	element (the tag) has been removed. The callback will use the same
368	also the most efficient match (by far).	311	environment as the default callback (see above).
369		312
370	Example: create a port and bind receivers on it in one go.	313	Example: create a port and bind receivers on it in one go.
371		314
372	my $port = rcv port,	315	my $port = rcv port,
373	msg1 => sub { ...; 0 },	316	msg1 => sub { ... },
374	msg2 => sub { ...; 0 },	317	msg2 => sub { ... },
375	;	318	;
376		319
377	Example: create a port, bind receivers and send it in a message elsewhere	320	Example: create a port, bind receivers and send it in a message elsewhere
378	in one go:	321	in one go:
379		322
380	snd $otherport, reply =>	323	snd $otherport, reply =>
381	rcv port,	324	rcv port,
382	msg1 => sub { ...; 0 },	325	msg1 => sub { ... },
383	...	326	...
384	;	327	;
		328
		329	Example: temporarily register a rcv callback for a tag matching some port
		330	(e.g. for a rpc reply) and unregister it after a message was received.
		331
		332	rcv $port, $otherport => sub {
		333	my @reply = @_;
		334
		335	rcv $SELF, $otherport;
		336	};
385		337
386	=cut	338	=cut
387		339
388	sub rcv($@) {	340	sub rcv($@) {
389	my $port = shift;	341	my $port = shift;
390	my ($noderef, $portid) = split /#/, $port, 2;	342	my ($noderef, $portid) = split /#/, $port, 2;
391		343
392	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	344	$NODE{$noderef} == $NODE{""}
393	or Carp::croak "$port: rcv can only be called on local ports, caught";	345	or Carp::croak "$port: rcv can only be called on local ports, caught";
394		346
395	if (@_ == 1) {	347	while (@_) {
		348	if (ref $_[0]) {
		349	if (my $self = $PORT_DATA{$portid}) {
		350	"AnyEvent::MP::Port" eq ref $self
		351	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		352
		353	$self->[2] = shift;
		354	} else {
396	my $cb = shift;	355	my $cb = shift;
397	delete $PORT_DATA{$portid};
398	$PORT{$portid} = sub {	356	$PORT{$portid} = sub {
399	local $SELF = $port;	357	local $SELF = $port;
400	eval {	358	eval { &$cb }; _self_die if $@;
401	&$cb	359	};
402	and kil $port;
403	};	360	}
404	_self_die if $@;	361	} elsif (defined $_[0]) {
405	};
406	} else {
407	my $self = $PORT_DATA{$portid} \|\|= do {	362	my $self = $PORT_DATA{$portid} \|\|= do {
408	my $self = bless {	363	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
409	id => $port,
410	}, "AnyEvent::MP::Port";
411		364
412	$PORT{$portid} = sub {	365	$PORT{$portid} = sub {
413	local $SELF = $port;	366	local $SELF = $port;
414		367
415	eval {
416	for (@{ $self->{rc0}{$_[0]} }) {	368	if (my $cb = $self->[1]{$_[0]}) {
417	$_ && &{$_->[0]}	369	shift;
418	&& undef $_;	370	eval { &$cb }; _self_die if $@;
419	}	371	} else {
420
421	for (@{ $self->{rcv}{$_[0]} }) {
422	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
423	&& &{$_->[0]}	372	&{ $self->[0] };
424	&& undef $_;
425	}
426
427	for (@{ $self->{any} }) {
428	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
429	&& &{$_->[0]}
430	&& undef $_;
431	}	373	}
432	};	374	};
433	_self_die if $@;	375
		376	$self
434	};	377	};
435		378
436	$self
437	};
438
439	"AnyEvent::MP::Port" eq ref $self	379	"AnyEvent::MP::Port" eq ref $self
440	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	380	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
441		381
442	while (@_) {
443	my ($match, $cb) = splice @_, 0, 2;	382	my ($tag, $cb) = splice @_, 0, 2;
444		383
445	if (!ref $match) {	384	if (defined $cb) {
446	push @{ $self->{rc0}{$match} }, [$cb];	385	$self->[1]{$tag} = $cb;
447	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
448	my ($type, @match) = @$match;
449	@match
450	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
451	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
452	} else {	386	} else {
453	push @{ $self->{any} }, [$cb, $match];	387	delete $self->[1]{$tag};
454	}	388	}
455	}	389	}
456	}	390	}
457		391
458	$port	392	$port
…		…
513	will arrive, or the monitoring action will be invoked after possible	447	will arrive, or the monitoring action will be invoked after possible
514	message loss has been detected. No messages will be lost "in between"	448	message loss has been detected. No messages will be lost "in between"
515	(after the first lost message no further messages will be received by the	449	(after the first lost message no further messages will be received by the
516	port). After the monitoring action was invoked, further messages might get	450	port). After the monitoring action was invoked, further messages might get
517	delivered again.	451	delivered again.
		452
		453	Note that monitoring-actions are one-shot: once released, they are removed
		454	and will not trigger again.
518		455
519	In the first form (callback), the callback is simply called with any	456	In the first form (callback), the callback is simply called with any
520	number of C<@reason> elements (no @reason means that the port was deleted	457	number of C<@reason> elements (no @reason means that the port was deleted
521	"normally"). Note also that I<< the callback B<must> never die >>, so use	458	"normally"). Note also that I<< the callback B<must> never die >>, so use
522	C<eval> if unsure.	459	C<eval> if unsure.
…		…
683	my $id = "$RUNIQ." . $ID++;	620	my $id = "$RUNIQ." . $ID++;
684		621
685	$_[0] =~ /::/	622	$_[0] =~ /::/
686	or Carp::croak "spawn init function must be a fully-qualified name, caught";	623	or Carp::croak "spawn init function must be a fully-qualified name, caught";
687		624
688	($NODE{$noderef} \|\| add_node $noderef)	625	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
689	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
690		626
691	"$noderef#$id"	627	"$noderef#$id"
692	}	628	}
693		629
694	=back	630	=item after $timeout, @msg
695		631
696	=head1 NODE MESSAGES	632	=item after $timeout, $callback
697		633
698	Nodes understand the following messages sent to them. Many of them take	634	Either sends the given message, or call the given callback, after the
699	arguments called C<@reply>, which will simply be used to compose a reply	635	specified number of seconds.
700	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
701	the remaining arguments are simply the message data.
702		636
703	While other messages exist, they are not public and subject to change.	637	This is simply a utility function that come sin handy at times.
704		638
705	=over 4
706
707	=cut	639	=cut
708		640
709	=item lookup => $name, @reply	641	sub after($@) {
		642	my ($timeout, @action) = @_;
710		643
711	Replies with the port ID of the specified well-known port, or C<undef>.	644	my $t; $t = AE::timer $timeout, 0, sub {
712		645	undef $t;
713	=item devnull => ...	646	ref $action[0]
714		647	? $action[0]()
715	Generic data sink/CPU heat conversion.	648	: snd @action;
716		649	};
717	=item relay => $port, @msg	650	}
718
719	Simply forwards the message to the given port.
720
721	=item eval => $string[ @reply]
722
723	Evaluates the given string. If C<@reply> is given, then a message of the
724	form C<@reply, $@, @evalres> is sent.
725
726	Example: crash another node.
727
728	snd $othernode, eval => "exit";
729
730	=item time => @reply
731
732	Replies the the current node time to C<@reply>.
733
734	Example: tell the current node to send the current time to C<$myport> in a
735	C<timereply> message.
736
737	snd $NODE, time => $myport, timereply => 1, 2;
738	# => snd $myport, timereply => 1, 2, <time>
739		651
740	=back	652	=back
741		653
742	=head1 AnyEvent::MP vs. Distributed Erlang	654	=head1 AnyEvent::MP vs. Distributed Erlang
743		655
…		…
762	convenience functionality.	674	convenience functionality.
763		675
764	This means that AEMP requires a less tightly controlled environment at the	676	This means that AEMP requires a less tightly controlled environment at the
765	cost of longer node references and a slightly higher management overhead.	677	cost of longer node references and a slightly higher management overhead.
766		678
		679	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		680	uses "local ports are like remote ports".
		681
		682	The failure modes for local ports are quite different (runtime errors
		683	only) then for remote ports - when a local port dies, you I<know> it dies,
		684	when a connection to another node dies, you know nothing about the other
		685	port.
		686
		687	Erlang pretends remote ports are as reliable as local ports, even when
		688	they are not.
		689
		690	AEMP encourages a "treat remote ports differently" philosophy, with local
		691	ports being the special case/exception, where transport errors cannot
		692	occur.
		693
767	=item * Erlang uses processes and a mailbox, AEMP does not queue.	694	=item * Erlang uses processes and a mailbox, AEMP does not queue.
768		695
769	Erlang uses processes that selctively receive messages, and therefore	696	Erlang uses processes that selectively receive messages, and therefore
770	needs a queue. AEMP is event based, queuing messages would serve no useful	697	needs a queue. AEMP is event based, queuing messages would serve no
771	purpose.	698	useful purpose. For the same reason the pattern-matching abilities of
		699	AnyEvent::MP are more limited, as there is little need to be able to
		700	filter messages without dequeing them.
772		701
773	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	702	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
774		703
775	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	704	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
776		705
777	Sending messages in Erlang is synchronous and blocks the process. AEMP	706	Sending messages in Erlang is synchronous and blocks the process (and
778	sends are immediate, connection establishment is handled in the	707	so does not need a queue that can overflow). AEMP sends are immediate,
779	background.	708	connection establishment is handled in the background.
780		709
781	=item * Erlang can silently lose messages, AEMP cannot.	710	=item * Erlang suffers from silent message loss, AEMP does not.
782		711
783	Erlang makes few guarantees on messages delivery - messages can get lost	712	Erlang makes few guarantees on messages delivery - messages can get lost
784	without any of the processes realising it (i.e. you send messages a, b,	713	without any of the processes realising it (i.e. you send messages a, b,
785	and c, and the other side only receives messages a and c).	714	and c, and the other side only receives messages a and c).
786		715
…		…
798	eventually be killed - it cannot happen that a node detects a port as dead	727	eventually be killed - it cannot happen that a node detects a port as dead
799	and then later sends messages to it, finding it is still alive.	728	and then later sends messages to it, finding it is still alive.
800		729
801	=item * Erlang can send messages to the wrong port, AEMP does not.	730	=item * Erlang can send messages to the wrong port, AEMP does not.
802		731
803	In Erlang it is quite possible that a node that restarts reuses a process	732	In Erlang it is quite likely that a node that restarts reuses a process ID
804	ID known to other nodes for a completely different process, causing	733	known to other nodes for a completely different process, causing messages
805	messages destined for that process to end up in an unrelated process.	734	destined for that process to end up in an unrelated process.
806		735
807	AEMP never reuses port IDs, so old messages or old port IDs floating	736	AEMP never reuses port IDs, so old messages or old port IDs floating
808	around in the network will not be sent to an unrelated port.	737	around in the network will not be sent to an unrelated port.
809		738
810	=item * Erlang uses unprotected connections, AEMP uses secure	739	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
846	This also saves round-trips and avoids sending messages to the wrong port	775	This also saves round-trips and avoids sending messages to the wrong port
847	(hard to do in Erlang).	776	(hard to do in Erlang).
848		777
849	=back	778	=back
850		779
		780	=head1 RATIONALE
		781
		782	=over 4
		783
		784	=item Why strings for ports and noderefs, why not objects?
		785
		786	We considered "objects", but found that the actual number of methods
		787	thatc an be called are very low. Since port IDs and noderefs travel over
		788	the network frequently, the serialising/deserialising would add lots of
		789	overhead, as well as having to keep a proxy object.
		790
		791	Strings can easily be printed, easily serialised etc. and need no special
		792	procedures to be "valid".
		793
		794	And a a miniport consists of a single closure stored in a global hash - it
		795	can't become much cheaper.
		796
		797	=item Why favour JSON, why not real serialising format such as Storable?
		798
		799	In fact, any AnyEvent::MP node will happily accept Storable as framing
		800	format, but currently there is no way to make a node use Storable by
		801	default.
		802
		803	The default framing protocol is JSON because a) JSON::XS is many times
		804	faster for small messages and b) most importantly, after years of
		805	experience we found that object serialisation is causing more problems
		806	than it gains: Just like function calls, objects simply do not travel
		807	easily over the network, mostly because they will always be a copy, so you
		808	always have to re-think your design.
		809
		810	Keeping your messages simple, concentrating on data structures rather than
		811	objects, will keep your messages clean, tidy and efficient.
		812
		813	=back
		814
851	=head1 SEE ALSO	815	=head1 SEE ALSO
852		816
853	L<AnyEvent>.	817	L<AnyEvent>.
854		818
855	=head1 AUTHOR	819	=head1 AUTHOR

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.44 by root, Wed Aug 12 21:39:58 2009 UTC vs.
Revision 1.64 by root, Fri Aug 28 00:58:44 2009 UTC